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Bridge

to do other

[edit]
  • VA3 - Architecture,
  • HS:
    • GARC ?
    • Soruce titles: uniform capitlz
    • Only a few sources have ISSN; add to all, or none? from WP:ISSN "On Wikipedia, an ISSN is an optional part of a citation to a particular article (adding it never hurts, but it is not strictly necessary when a direct URL or DOI is provided to the full text of the article). "
    • uniform bundling approach: two cites are using bullets
  • DYK Bridge ... waiting for review

To Do

[edit]
  • Failures: need global data/info: per PR #2
  • COnvert:
    • Missing a kilometres to miles conversion under the section "Suspension bridge"
    • and the section "Long, multi-span bridge"
  • Deck: Clarify definition: some sources define "deck" to include the truss, girder or beam that is below it. Other define it ias the top surface of the deck truss/girder/beam (or surface of the bottom of a thru truss). The Shen chapter (concrete deck) makes it clear that he uses "deck" to exclude the beam girder
    • vol 2: COncrete Deck: has diagrams that show deck resting on beams, girders & trusses: 579, 575, 574
    • Vol 1 Orthotropic deck chapter has diargrams: 592, 594, 598
  • A box girder may be concrete or steel
    • A steel box girer has teh deck on top, ussually, so it looks a lot like a deck truss bridge; but the steel box gircer has a recgatngualar corss section, and the deck normally is sider that the box (example: golden gate bridge, and many suspensiton bridge and cable stay bridges)
  • Add cite to caption of Acero postesado.jpg
    • - E.g. vol 2 p 413 "Cable stayed" chapter
  • REmove stmt "pre stresing rqrd in lower part of concrete beams" until have a source for it
  • New sources for bridge operaiotns/mainteance from Vol 5 of BEH:
    • 9 Bridge Management Using Pontis and Improved Concepts 233 Gongkang Fu and Dinesh Devaraj (NOTE: Pontis is a US bridge mgmt sw app)
    • 10 Bridge Health Monitoring 247 Dan M. Frangopol and Sunyong Kim
    • 11 Bridge Maintenance 269 Sreenivas Alampalli
    • 12 Nondestructive Evaluation Methods for Bridge Elements 301 Glenn Washer
    • 13 Bridge Inspection 337-350 Joyce E. Copelan
  • NEW sources for COnstruction: in Volume 5 (ISBN 78-1-4398-5233-0 )
    • 4 Cable-Supported Bridge Construction 85-112 Junfeng Shi, Tianqing Yu, Yaodong Liu, Yinghua Bai, and Rui Xiong
      • Probably could be used instead of Gimsing which is from 1997 !!
    • 3 Concrete Bridge Construction 67-84 Simon A. Blank, Michael M. Blank, and Hamid Kondazi
    • 1 Steel bridge constrcution Steel Bridge Construction 1-50 Jackson Durkee
  • NEW: any material from Vol 4 "Seismic design"?
  • Extradosed Bridges the sub article has some good sources and material specifically
    • there are recent developments from the nineteen nineties onwards
    • mostly in japan and south korea
    • Engineers consider them a form of external post stressing rather than cable stayed
  • Enhance existing material on concrete filled steel tube to say it is a kind of reinforced concrete; (as extrdosed is a kind of post-tensioned prestressed concrete); however, other sources instead emphasize that it is primarily a steel tube, and the concrete delays/minimizes buckling of the steel tube.

SAVE for FA nom: notes on rationale & rejected topics

[edit]
  • Be prepared recite recent bridge developments such as cable stayed bridges in the 1950s through 1980s extra dosed bridges in the 1990s and concrete filled tube arch bridges in the 21st century And the PPWS method of pulling strands in the late 20th century
  • Italian book titles only cap the 1st word, so "I quattro libri dell'architettura" is correct
  • Troitsky source is great: broad & clear; I'm not using it cept for one senetnce. So if cites are needed, that may bve a good source to go to first. HOWEVER it is a bit dated: 1994
  • Panorama issues of images: see File:ViaducdeMillau.jpg for key notes & insight
    • Pics of Modern french bridges must be hosted on English WP, not Commons e.g. Millau
  • Review of images done on 24 oct 2025
  • Falsework image: if rejected, other images are:
      • File:ETH-BIB Hundwil Waldstatt, neue Hundwilertobelbrücke, Lehrgerüst Ans 01200-007.tif
      • File:Alte Rosengartenbrücke im Bau 1912-1913.jpg
      • File:Walnut-Lane-Bréck--001--w.jpg
      • Wachusett Dam, relocation Central Massachusetts Railroad, building railroad bridge over waste channel, Clinton, Mass., Aug. 2, 1905 - DPLA - 7aa53750bbf55eb532eecdb0f675e884.jpg
  • Constracting approaches: design/build vs design/bid/build. --- too generic, not speicfic to bridges
  • Cost / econiomics / financing / tolls ??? not sure about this. - too generic, not speicfic to bridges Sources are sparse & may be more appropriate for Infrastrucutre articles, not "bridge as a structure".
    • Possible source: Br Eng Handbook vol 5 p 181 chapter Accelerated Bridge Construction; section 7.3.1.4 Innovative Financing/Innovative Contracting "Align financing options with the goals of the project by matching anticipated cash flow with project management, while recognizing competing priorities for existing resources. Financing tools could include cost-sharing strategies, tolling mechanisms, contractor financing, leveraging techniques, credit assistance, and cost management and containment concepts. Explore state-of-the art contracting practices and obtain a better knowledge of how these techniques could be selected, organized, and assembled to match the specific situations needed on this project. Techniques to be considered include performance-related specifications, warranties, design-build (DB), maintain, operate, cost plus time, partnering escalation agreements, lane rental, incentive/disincentives, value engineering (VE), and any other innovative contracting techniques that would apply to the project. See Section 7.4 for more discussions on contracting strategies."

Profession & licensing

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  • a source: Occupational outlook handbook

by U. S. Department of Labor (COR) Publication date 2008 https://archive.org/details/occupationaloutl00usde_2/page/148/mode/1up?q=engineer

p 148: "Licensure. All 50 states and the District of Columbia require licensure for engineers who offer their services directly to the public. Engineers who are licensed are called professional engineers (PE). This licensure generally requires a degree from an ABETaccredited engineering program, four years of relevant work experience, and successful completion of a state examination. Recent graduates can start the licensing process by taking the examination in two stages. The initial Fundamentals of Engineering exam examination can be taken upon graduation. Engineers who pass this examination commonly are called engineers in training (EIT) or engineer interns (EI). After acquiring suitable work experience, EITs can take the second examination, the Principles and Practice of Engineering exam. Several states have imposed mandatory continuing education requirements for relicensure. Most states recognize licensure from other states, provided that the manner in which the initial license was obtained meets or exceeds their own licensure requirements. Many civil, electrical, mechanical, and chemical engineers are licensed PEs. Independent of licensure, various certification programs are offered by professional organizations to demonstrate competency in specific fields of engineering."

p 148: "Certification and advancement. Beginning engineering graduates usually work under the supervision of experienced engineers and, in large companies, also may receive formal classroom or seminar-type training. As new engineers gain knowledge and experience, they are assigned more difficult projects with greater independence to develop designs, solve problems, and make decisions. Engineers may advance to become technical specialists or to supervise a staff or team of engineers and technicians. Some may eventually become engineering managers or enter other managerial or sales jobs. In sales, an engineering background enables them to discuss a product's technical aspects and assist in product planning, installation, and use. (See the statements under management and business and financial operations occupations and the statement on sales engineers elsewhere in the Handbook.)


  • US Professional Engineer: every state has their own unique rquirements, but over time they have gradually become similar (driven by comity/reciprocity)

- After gettign a eng degree & accumulating experitienc,e the eng takes the PE exam adminsistred by the NCEES (nationwide org): if pass, then they become a PE in their state, and may apply to get licensed in other states as well

    • A soruce discussiogn US lic esp comity between states: {{cite web |url=http://www.nspe.org/Licensure/Resources/LicComity/index.html |publisher=National Society of Professional Engineers |access-date=2008-03-14 |year=2008 |title=Licensure by Comity |archive-date=2008-09-08 |archive-url=https://web.archive.org/web/20080908082639/http://www.nspe.org/Licensure/Resources/LicComity/index.html |url-status=live }}

History

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Licensure in the United States began in the State of Wyoming whe


  • Bennet 1999 p 24: "This was the era [1700s] when the civil engineering as a profession was born, when the first school of engineering was established in Paris at the Ecole de Paris during the reign of Louis XV. The director of the school was Jacques Gabriel, who had designed the Pont Royal. He was given the responsibility of collecting and assimilating all the information and knowledge there was on the science and history of bridges, buildings, roads, and canals. ...With such a vast bank of collective knowledge, it was inevitable that building architecture and civil engineering should be separated into the two fields of expertise. It was suggested it was not possible for one man in his brief life to master the essentials of both subjects. Moreover, it became clear that the broad education received in civil engineering at the Corps des Ponts et Chaussées (or Bridge and Highway Corps) at the Ecole de Paris was not sufficient for the engineering of the large projects. More specialized training was needed in bridge engineering. In 1747 the first school of bridge engineering was founded in Paris at the historic École nationale des ponts et chaussées The founder of the school was Trudiane, and the first teacher and Director was a brilliant ABOVE: Rennie’s “New London Bridge” young engineer named Jean-Rodolphe Perronet. under construction. Jean Perronet has been called the “father of modern. bridge engineering” for his inventive genius and design of the greatest masonry arch bridges of the century. In his hand the masonry arch reached perfection. The arch he chose was the curve of a segment of a circle of larger radius, instead of the familiar three-centered arch. To express the slenderness of the arch he raised the haunch of the arch considerably above the piers. Perronet was the first person to realize that the horizontal thrust of the arch was carried through the spans to the abutments, and that the piers, in addition to ~ carrying the vertical load, also had to resist the difference between adjacent span ..."


Some existing certification systems for bridge engineers 

   Finland FISE Certifications: In Finland, structural engineering qualifications are managed by FISE, which provides multiple levels of certification based on the complexity of projects. Certifications range from "A" for basic projects to "AAA" for highly demanding structures. Proficiency in Eurocodes, especially EN 1990 to EN 1999, is a fundamental requirement. Eurocode Proficiency: Mastery of Eurocodes is crucial for all certified engineers to ensure compliance with European standards.
   Sweden Trafikverket Approval: Swedish bridge engineers must obtain approval from Trafikverket (the Swedish Transport Administration), particularly for large infrastructure projects. Engineers undergo specialized training and assessments based on national and European codes. Education and Training: Passing dedicated courses and exams focused on local standards is often mandatory.
   Norway Statens vegvesen Requirements: The Norwegian Public Roads Administration mandates certifications for bridge engineers, especially for public projects. Knowledge of Eurocodes is essential, and engineers must prove their ability to handle Norway's harsh environmental conditions. Experience in Complex Projects: Engineers are expected to have significant experience in various bridge types to ensure robust designs.
   United States Professional Engineer (PE) License: In the U.S., bridge engineers must earn a PE license, which involves passing the Fundamentals of Engineering (FE) and the Professional Engineering (PE) exams. A minimum of four years of practical experience is required, though more complex projects might necessitate 8-10 years of experience. Bridge Inspector Certification: The National Bridge Inspection Standards (NBIS) require bridge inspectors to hold specialized certifications.
   Germany Ingenieurkammer Membership: In Germany, bridge engineers must hold a degree in engineering (e.g., Dipl.-Ing.) and often need membership in a regional engineering chamber. For major projects, stringent regulatory standards apply. Baumusterprüfung: This involves having complex designs approved by an independent body to ensure compliance and safety.
   United Kingdom Chartered Engineer (CEng): Bridge engineers must achieve Chartered Engineer status, which is granted by professional bodies such as the Institution of Civil Engineers (ICE). This typically requires 5-8 years of experience and evidence of working on diverse and technically challenging projects. Compliance with Eurocodes and British Standards: Engineers must be adept in both Eurocodes and the UK's own standards.
   Australia and New Zealand Chartered Professional Engineer (CPEng): Registration with Engineers Australia or an equivalent body is essential, requiring 5-7 years of experience. In more complex infrastructure roles, 8-10 years is common. Approval by Local Authorities: Some projects require additional certifications to meet local regulatory demands.
   Canada Professional Engineer (P.Eng) License: Engineers need a P.Eng license, equivalent to the PE license in the U.S. Provincial regulations may impose extra criteria for bridge design. Bridge Safety Engineer Certification: In provinces like British Columbia, further certifications might be necessary to ensure bridge safety.
   Vietnam Local Engineering Licenses: Bridge engineers must adhere to national construction standards, and certification is overseen by local authorities. Large projects often involve collaboration with international experts, increasing the need for global engineering proficiency.


  • Same linked in site lists experience requiremetns:


Required experience for certification

Experience requirements for bridge engineers are stringent and vary based on the complexity of projects and local regulations: 

   Europe: Basic Certifications: 3-5 years of structural engineering experience, with emphasis on bridge projects. Advanced Certifications: 8-10 years, particularly for complex bridges such as cable-stayed or arch structures. Scandinavia: Engineers may need 5-10 years of experience, especially for high-risk infrastructure projects.
   United States: PE License: Requires 4 years of experience, but complex projects often demand 8-10 years. Senior Roles: 10-15 years for large-scale or critical infrastructure projects.
   United Kingdom: CEng Status: Typically 5-8 years, with complex bridge work necessitating up to 15 years of experience.
   Canada: P.Eng License: At least 4 years of experience, with 6-10 years for major infrastructure. Specialized Safety Roles: Up to 10 years for critical safety positions.
   Australia/New Zealand: CPEng: 5-7 years, with complex projects requiring up to 15 years. Infrastructure Leadership: Extensive experience in design and project management.
   Vietnam and Asia: Local Projects: 3-5 years for simpler projects, 8-10 years for complex bridges. International Collaboration: 10-15 years for high-profile projects involving foreign partners.


  • US apparently is world leader in licensing requirementsds: other countries have few requirements, sometimes only a college or technical school degree; sometimes no reqmts at all (Germany until 1965)

-Title = The History of the National Council of Examiners for Engineering and Surveying - Third edition = year= 2004 - PUblisher: The National Council of Examiners for Engineering and Surveying

  • CAnada: pp 71,77
  • p 366 mentiosn some eng organizationsd:

The Institute of Engineers, Australia ɤ The Canadian Council of Professional Engineers ɤ The Canadian Engineering Accreditation Board of the Canadian Council of Professional Engineers ɤ Canadian Council of Land Surveyors ɤ Canadian Institute of Surveying and Mapping ɤ The Institution of Engineers of Ireland ɤ The Institution of Professional Engineers of New Zealand ɤ The Engineering Council of the United Kingdom ɤ Pan American Federation of Engineering Societies ɤ The European Federation of Engineering Associations ɤ Royal Flemish Society of Engineers-Belgium ɤ World Federation of Engineering Organizations ɤ United Nations Educational and Scientific Organization


  • pp 123-125 NCEES interl overview "By 1993, the Committee on International

Relations had decided that ABET was the appropriate organization to evaluate foreign degrees but later changed this decision. The Council would still compile a database from these applications to be available to the Member Boards. The committee had identified eight countries of highest priority regarding information in licensure procedures (Canada, India, Mexico, the United Kingdom, China, Japan, the Philippines, and Russia.) In 1994, the committee adopted a detailed resolution establishing a procedure for the evaluation of foreign engineering degrees. The Committee on Foreign Engineering Education Evaluation Program (FEEEP) identified the American Association of Collegiate Registrars and Admissions Officers (AACRAO) as the organization to help evaluate foreign engineering education. Applicants from programs conducted outside the United States and not subject to Washington Accord recognition would be advised to contact the NCEES for evaluation of their engineering credentials. The NCEES, in turn, would rely on an AACRAO evaluation to determine whether or not the education appeared to satisfy requirements of an ABET-accredited program. The completed evaluation would then be forwarded to the appropriate jurisdiction for determination of whether the education met its local requirements. U.S. Licensure in an International Market In 1991, the Committee on International Relations reported on its charge of tabulating and analyzing other countries’ regulation of engineering and their laws, rules, regulations, and codes of conduct. It was to compare these with the NCEES Model Law, Model Rules of Professional Conduct, etc. and develop a format for reporting data to Member Boards. The committee also had been charged with developing a draft policy on NCEES’ role in international activities. The policy they drafted was that “The NCEES proactively monitor, evaluate, and document registration requirements of other countries.” The countries tabulated were Belgium, Germany, Denmark, Spain, France, the United Kingdom, Greece, Italy, Ireland, and the Netherlands. With a few exceptions where a degree is required, there appeared to be few restrictions on the practice of engineering in these countries. The U.S. system of licensing professional engineers, according to the committee on the study of the U.S. Recognized Engineers, was considered to be the most rigorous system in the world in setting standards for competency and in the regulation of the practice of engineering to protect the welfare of the public. Surely, this system was destined as a pacesetter in the internationalization of engineering. In fact, by 1992, it was reported that the Council had received inquiries from Russia, Israel, and Japan about the use of the examination (potentially a new source of revenue) and that Japan was interested in establishing a registration process based on an examination similar to the Council’s. President William L. Karr reported that an interim agreement with Canada had been signed but that examinations were a key stumbling block to a final agreement. Karr expressed the belief that a final agreement would “most likely be used as the starting place for all other international agreements that the Council will be involved with.” In negotiations with other countries, because most of them did not include an examination in their licensure process, the issue was whether or not experience could be substituted for examinations, and, if so, how many years. USCIEP had recommended 15 years of post- baccalaureate progressive engineering experience. The paradox was that on the one hand the Council feared a dismantling of the licensure process based on examinations which it had painstakingly developed over a period of decades,

Dampers material

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  • NO DAMPER MATERIAL: Bennett 1999; Barker;
  • Manual of Bridge ... ChaPTERS: AUTHOR Farquar "Cable-Stay bridges" (pp 549 to 594); Author Jones & Howells "Supsension bridges" (pp 595-662)
    • P 559 ". In order to provide adequate fatigue resistance it is essential that rotation of the strands at the face of the wedge grips, due to changes in stay load or wind oscillation, does not occur. Dampers located some distance in front of the anchor face prevent this by restraining the strands. An outer polyethylene tube covers the strand bundle providing protection against impact damage and preventin..."
    • p 589 "These movements were successfully controlled by the introduction of tuned mass damping devices located at the top of each pylon and at eight locations for torsion and eight locations for bending within the steel box deck. The tuned mass damper consisted of a mass hanging from tension springs with ‘viscodampers’ attached. These dampers are cylinders, which are attached to the mass, and contain a viscous fluid with a plunger immersed in it. The plunger is attached to the bridge deck. The installation of tuned mass dampers on the Rama IX Bridge has successfully controlled any limited amplitude response to wind..."
    • p 590 (Cable stays: rivulets) "Several methods have been employed to reduce or eliminate these oscillations. A simple method, that is incorporated in most stay systems and does not alter the appearance of the bridge, is with dampers installed between the steel anchorage pipes and the stay. Ribs, either parallel or helically wound, on the outer surface of the stay prevent the rivulets forming long continuous lengths and thus interfering with the aerodynamic behaviour. .."
    • P 619: Movement of deck ENDS of a suspensios bridge as deck expands and contractds: "Because of its continuity through the tower, the deck will experience increased bending moments in this area as it conforms to the angular rotation of the main cable at the saddles, and there will be increased deck longitudinal movements at the anchorages. These increased movements require the provision of a larger movement joint, and it may be necessary (as on the Storebelt East and Hgga Kusten bridges) to provide a hydraulic damper or lock-up device. These resist loads due to traffic braking or wind gust loads, but permit slow longitudinal movements due to temperature changes."
  • CHen 1999
    • P 18.17-18.18 "Increase Structural Damping. Damping, a countermeasure based on structural mechanics, is effective in decreasing the amplitude of vortex-induced oscillations which are often observed during the construction of the main towers and so on. Tuned mass dampers (TMD) and tuned liquid dampers (TLD) have also been used to counter this phenomenon in recent years. Active mass dampers (AMD), which can suppress vibration amplitudes over a wider frequency band, have also been introduced."
    • P 19.14 "Various measures have been used to reduce the seismic response of cable-stayed bridges [1]. They range from a simple shock damper with a hydraulic cylinder that freezes at fast motion, to different types of friction dampers. Letting the bridge girder swing for a certain distance like a pendulum is another efficient way of reducing the seismic response. This is especially effective for out-of-phase motions. Because many cable-stayed spans are in the range of the half wavelengths of seismic motions, the out-of-phase motion can create very large reactions in the structure. A partially floating girder is often found to be very advantageous."
    • P 19.15: "The knowledge of cable vibrations has also progressed extensively. The first stay cable vibration problem appeared in the Neuenkamp Bridge. This was a wake vibration of two parallel and horizontally located cables. The problem was new at that time. It was identified, and further vibration was suppressed by connecting the pair of cables together with a damper. This concept was used for several other subsequently built bridges.... Severe cable vibrations were observed in the Brotone Bridge. Dampers were installed and they were successful in suppressing the vibrations. The same concept was used for the Sunshine Skyway."
    • p 649-650 [Tall towers for Cable-stay or suspension: Steel towers can sway/vibrate much more than concrete tower; especially during construction; often: dampers must be put inside the towers during construction; then after the wight of the cables & deck is put onto the towers, the dampers are no longer needed] "damping must be provided. This damping can be provided either by an external friction damper or, for taller towers, an internally mounted tuned mass damper."
  • Brown
    • p 170 [first TUned mass damper on a suspension bridge 1995 hi-wind area: Pont de Normandie] "was included on each deck, capable of moving in any direction to dampen its natural frequency of vibration. It was a step into the unknown, and the designers and builders of this unprecedented structure did not know until they tried whether these “tuned mass dampers” really would control two near half-kilometre lengths of..."
    • p 184: Millenium footbrindge in London "Arup then designed the remedy, a complex but visually unobtrusive system of viscous dampers and tuned mass dampers beneath the deck that absorb and neutralize any movement. After installation and successful testing, the bridge reopened — without its wobble — in March 2002."
    • p 203 GlossarY "Tuned mass damper A counterweight to subdue a bridge deck’s tendency to vibrate."


  • Gimsing source Cable supported bridges : concept and design
    • p 20 "Bronx–Whitestone Bridge .... However, the measures taken did not eliminate completely the vibrations, so further measures had to be taken, and in the 1980s large tuned mass dampers were installed.
    • p 417 "he problems related to wind-induced oscillations of the free-standing pylons will generally be more pronounced for steel pylons than for concrete pylons due to a steel structure’s smaller mass, larger flexibility, and lower damping. In a number of cases it has therefore been necessary to take special measures to achieve aerodynamic stability in the critical construction phases. Thus in Japan larger pylons often have tuned-mass dampers installed temporarily once a certain height has been reached and until a supplementary support is provided by the cable system.
    • p 445 Karnali River Bridge in Nepal. In this two-span bridge the girder had to be cantilevered from one side only, and as the main span was 325m long and the deck 10m wide then the cantilever-to-width ratio was 32.5. At the same time the application of a stiffening truss implied that the drag forces were quite large. It was, therefore, necessary not only to stabilize by using a temporary tuned-mass damper (as in the case of the Normandie Bridge) but also to support the cantilever by two sets of horizontal guy cables attached to the girder at distances of 150m and 239 m from the pylon and anchored on the opposite bank of the river [94.11].
    • p 105 "For the replacement, strands with galvanized wires either in all layers or in the two outer layers only were used. At the same time the lower part of the strands were protected by a polyethylene tube and dampers were installed to reduce the wind induced oscillations. The cost of the strand replacements amounted to 28% of the initial cost of the entire cable-stayed portion of the Kohlbrand Bridge."
    • p 272-3 "Besides the addition of stabilizing ropes stay cable oscillations have also been suppressed by installing viscous dampers that will prevent large amplitudes building up. Thus, Figure 3.208 shows the dampers that were erected in the Brotonne Bridge after experiencing severe oscillations of the stay cables. In this case the dampers were made as ordinary shock absorbers similar to those used in automobile

Source material

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David Bennett (1999) full book The Creation of Bridges: From Vision to Reality - the Ultimate Challenge of Architecture, Design and Distance

[edit]
  • Same author as THe Chapter 1 from the 2000 "Manual" book is NOT in this 1999 book, so there is little DIRECT overlap; the single chapter in the 2000 Manual book appears to be an extract or distillation of the entire 1999 "The Creation of" book"" maybe?
  • Chapters:
    • 1: Early history [already covered in "Manual" book chapter by same author
    • 2: Image gallery
    • 3: Design/mechanics pp 66-97
    • 4: List of great bridges pp 99-150
    • 5: Disasters /Failure analysis pp 152-173
    • 6: Famous Bridge engineers: pp 174-225
  • THerefore I really only want chapter 3 from this book
  • CHPATER 3: DESIGN & MECHANICS
  • p 67-68: "In understanding how bridges work there are two important structural terms to recognize—tension and compression. All structures—whether a house, a skyscraper, a dome, an arch, or a suspension bridge—are either in tension or compression. If you can understand how tension and compression forces work, then you will begin to appreciate how bridges are able to span. What are tension and compression, and how can we recognize them? We may not be able to “feel” the forces in a bridge structure, but we can recognize the effects of tension and compression quite easily. For instance, if we pull on a rope or a string we say that we have put the string or rope in “tension.” If you push down on a wooden post or hammer a nail into wood, you are putting the post or the nail into “compression.” To find out how it “feels” to be in tension, hold the knob of a closed door and pull on it. Your arm is put in tension: it is being stretched. If you want to feel compression, push with your arm stretched against the door. Your arm is now in compression. "
  • p 68 MATERIALS are GOOD IN COMPRESSION or TENSION "As a bridge bends under the weight of the load it is supporting, some parts of the structure may go into tension and others go into compression. For instance, an arch goes only into compression, while a suspension cable stretches and undergoes tension—but a truss or beam will undergo both tension and compression at the same time. Materials for bridge building that are useful in compression are stone, brick, and plain concrete. They are brittle and will crack if they are stretched or bent. Materials that are good in tension are rope, bamboo, and wire. They can be stretched, but, because they are not very rigid, they will not hold their shape under compression. However, highly engineered modern materials like steel and reinforced concrete are good in both tension and compression. Successful bridge builders through the ages had to design bridges to suit the building materials that were available to them at the time."
  • p 68 REINFORCING CONCRETE, ESP NEAR SURFACE OR WHERE IN TENSION: "Concrete is very good in compression, but, if you try to bend it or stretch it— putting in into tension—it will crack and fail. For concrete to be ductile, so that it can bend and recover and be capable of resisting tension forces, it has to be reinforced with steel rods or bars—materials called, predictably, “reinforcement.” The reinforcement is positioned close to the face of the concrete that is in tension to prevent it cracking and to resist the tension stresses acting on it. Reinforcement placed in concrete will not rust, despite its being covered in wet concrete, because the pH of cement is so alkaline that it inhibits any rust and corrosion forces developing."
  • p 69 : PRESTRESS REGIONS OF CONCRETE THAT WILL BE IN TENSION: The prestress cancels out the (later) tension: "So why is it [prestressing] so useful? By putting the concrete into precompression it will not go into tension when a load is applied, because the precompression stress in the concrete can be made larger than the tension stress from the bending. This is a very simple explanation of how prestressed concrete works. It is much more complex than that in the design of a bridge beam because there are losses in the prestressing strand due to shrinkage of the concrete, and relaxation of the steel stress."
  • TERMINOLOGY: That Bennett uses term "precompression" instead of "prestress", which some other sources do also. Yet article Prestressed structure uses "precompression" in a different way: to mean pre-stress compression due to the strucutre's own dead weight (excluding pre/post cable tensioning). Therefore, I should probably avoid "precompression" cuz of this ambiguity. Use these terms:
    • Prestress (no hyphen) includes pre-tension and post-tension
    • Pre-tension and Post-tension (pre and post refer to before/after concrete cures)
      • (post includes both bonded and unbonded)
    • DONT USE: precompression, pre-compress, post-compress, post-stress
  • p 69: PRE vs POST TENSIONIGN: "When strands are placed in beams or box girders and tensioned before the concrete is placed in the forms, it is called prestressing. When the strands are tensioned after the concrete has hardened, it is called post-tensioning. In prestressing, the tension wires or strands are cut once the concrete surrounding them has hardened, thus transferring the force from the strand to the concrete. In post-tensioning, the strands are laid in position but are not tensioned. When the concrete has hardened, anchor plates are placed at the ends of the wires are tightened against them"
  • p 69: REINFORCED vs PRESTRESSED (Cannot copy this text, so paraphrasing) "[ prestressed concrete beams or box girders are 20% shallower (thickness) than equivalent-strenth reinforced concrete. TEhrefore, prestressed is preferred over reinforcing for modern concrete bridges in (a) beams; and (b) box girders; (c) decks [but not towers/piers/foundations, which use reinforcing]"
  • p 70 STEEL "Steel is processed and manufactured in factories and then assembled into beam sections, plate girders, trusses, and so forth at steel-fabrication yards, before they are transported to the bridge location. Steel is stronger than concrete and has an elastic modulus that is 15 times greater, making it 15 times more efficient than concrete, but also about that many times more expensive."
  • p 70: I-BEAM cross section: [cannot copy this text] - I-beams are generally the most efficient corss section: most strength for a fixed amount of steel.
  • p 70: STONE ARCHES: entire in compression.
  • P 72 ARCH: shapes: include semicircular vs flattened/elliptical vs pointed arch; vs segemented ( of a circle) arch
  • P 72 ARCH FORCE AT BOTTOM: "For a semicircular arch such as a Roman arch, which met the ground vertically, there is no outward thrust. Thus each arch span can be built independently of the next one, which was useful in Roman times, when they had to build a bridge across a river. However, the pier supports for such arches have to be very wide and massive, and the span quite limited. The flatter the curve of the arch, the greater is the outward thrust on the abutment, and the more unstable the arch becomes during construction."
  • p 73-74 STEEL ARCH BRIDGES - Modern arch bridges are either steel or concrete. Steel is lighter, requires smaller foundations, and can be erected by cantilevering, thus avoid the temporary formwork (moulds) required for concrete.
    • TERM: p 74 "Stub columns" are the vertical columns leading from arch up to deck.
    • TERM p 75 Through-arch: decks passes thru middle of arch (between a plain arch and a tied (aka bowstring) arch).
  • p 77-79 TRUSS GIRDERS: "One of the most simple and basic of bridge forms is the triangular truss. A simple triangular truss is made up of two inclined compression members and a horizontal tension bar or tie rod, which prevents the inclined members from opening up under load. The truss is self-contained and is supported from each end, to carry the imposed load as well as its own weight. It does not need abutments because there is no horizontal thrust. In some long-span [simple, single-row of triangle] trusses, the sagging of the tie rod under its own weight is reduced by support at mid-span from a hanger suspended from the top of the truss. Large trusses or composite trusses can be made by connecting triangular trusses together. Highway and railroad bridges spanning hundreds of feet are often built with trusses like this, mostly made of steel bar. The composite truss behaves very like a deep-flanged beam, with the truss upper chord acting like the upper flange of a steel beam, and the lower chord like of the steel beam. The diagonals of the truss connecting the upper and lower chord of the truss are much lighter than a full web and use less material. The rigidity and stiffness of the truss is due to the triangulated diagonals. Gustave Eiffel’s great bridges and towers were based on the lightness and rigidity of the truss [thus very economical with materials] "
    • BENNETT distinguishes between "Simple triangular truss" (a single row of triangles) vs "composite truss" with multiple rows s of triangles, supplemented by vertical and/or horizontal members/rods.
    • TERMINOLOGY: Individual triangle ediges are called "bars" or "Rods"
      • a"chord" is a full horizontal stretch of rods, e..g at top or bottom.
  • p 78: BOX GIRDER BEAM - Can have longer spans that I-beams (even if multilple); can be concrete or steel. - "Steel beams, plate-girder beams, and reinforcedand prestressed-concrete beams are suitable for relatively short spans for road and railroad bridges, but will require many supporting piers if they are to be built across a wide river or freeway interchange. By forming a box section which is hollow in the middle, a.very strong but economical girder beam can be built, which has a greater span range. The box-girder beam, whether it is made of steel or concrete, is very common for modern road or railroad viaducts, and has been used extensively for building elevated freeways along mountain ranges or over valleys in Europe. It was primarily developed for the rigid deck construction required for suspension or cable-stay bridges. The box-girder bridge was first conceived by Robert Stephenson for his Britannia Rail Bridge"
  • p 81 SUSPENSION BRIDGES: "Natural vegetable fibers like hemp and bamboo have been used for thousands of years to make strong ropes from which to suspend crude bridges or to secure masts and sails in strong winds. Nowadays we make thick steel rope by twisting individual steel wires to make a cable strand, which can measure a few inches to a few feet in diameter. The steel cable is protected by a plastic nylon sheath to prevent corrosion. Such cables can carry thousands of tons of force and are the basic load-carrying system of the longest type of bridge in the world - the suspension bridge"
  • p 84: SUSPENSION BRDIGES: ANCHORS and TENSION " A cable is a tension structure because it can work only in tension. But you cannot build a bridge with just a series of cable strands, since the cable must be supported by towers and anchored at each end to maintain its suspension or catenary shape. So here we have the basics of the suspension bridge: the tension ..." [cannot copy-paste thijs text} ... Cable and hangers are in tension; towers & foundation are in compression;
    • TERMINOLOGY: "hangers" = vertical wires from cable to deck
    • "caisson" _is_ an alternative for "foundation" when used in the context of a bridge tower in water.. The caisson is used during construction; but when digging & pile driving is done, it maybe filled with reinforced concrete, and then it becomes the foundation. But the term "caisson" may still be used for the foundation.
  • p 88: SUPSENSION STIFFNESS "How does the suspension bridge keep its shape as traffic moves over it? The cables, which will want to distort under load, are stabilized by the hangers that support the roadway from the suspension cable. As a load goes over the bridge at a particular point, the cable is held in shape by the hangers and the rigid bridge deck. To keep the horizontal distance between the cables constant, the bridge deck acts like a stiffening truss and maintains the shape of the suspension system."
  • p 88-89 SUSPENSION ANCHORS vs CABLE TENSION: The larger the sag of the cable between the towers, the less tension is in the cable, which in turn means smaller-diameter and less costly cables and smaller end anchors. The problem is that, in creating a larger sag, the towers that support the cables have to be built very high, and this extra cost often outweighs the saving in the cable costs. That is why many suspension bridges have a shallow curvature of their suspension cables. However, the shallow curvature increases the tension in the cables, so thicker cables and large anchor blocks have to be built to resist this force."
  • p 88-90 SPINNING THE SUSP. CABLES: "The cables of a suspension bridge can weigh hundreds of tons, making it impractical to make the entire cable on dry land. Instead the cables are “air-spun,” very like in a textile loom, with individual steel wires pulled across in pairs by a spinning wheel. To set up the spinning wheels, pilot ropes are taken across the span and hauled up over both towers and linked back to the anchors at each end. A catwalk is then assembled from the pilot ropes for each cable, suspended a few feet below the eventual position of the cables."
  • p 90: SUSPENSION BR FOUNDATIONS: "Usually suspension bridges have caisson ... [cannot copy paste] ... discusses foundations for susp bridges]
  • p 92-96: CABLE-STAY BRIDGES: .. tbs ... includes step-by-step construction steps for a particular bridge
    1. nearby construction yard for pre-building elements of the bridge; pilings for foundation; pour foundation
    2. Build the towers (aka pylons) - Lower portions used forms, and cocrete was pured into the forms; for upper part: Segments were pre-cast offsite, lifted into place; then the joints were poured on-site
    • Concrete deck was built in segemnts: stgarting at the towers and moving outward in both directions, equally. Segements were cast offsite, and lifted into place with a barge. Construciton used a moving cantilever thar moved along thd deck asa it was constructed.


  • ... in progress ...

David Bennett HISTORY - "The history and aesthetic development of bridges" - Chapter 1 in "Manual of Bridge Engineering (2000, Ed Ryall)

[edit]
  • THE sections of this chapter make a good outline for article paragraphs in History section
    • SECTIONS ARE: pp 1-34 Table of Contents of CHapter 1 The history and aesthetic development of bridges D. Bennett Lal The early history of bridges tail The age of timber and stone P12 Earliest records of bridges BiB The Romans 1.1.4 The Dark Ages and the brothers of the bridge bis The Renaissance 2 Eighteenth-century bridge building aed | The Age of Reason RZ The carpenter bridges 25 The railroad and the truss bridge if) The past 200 years: bridge development in the nineteenth and twentieth centuries ro The age of iron (1775-1880) j es The arrival of steel L333 Concrete and the arch 1.3.4 Cable stay bridges 1.4 Aesthetic design in bridges 1.4.1 Introduction 1.4.2 Bridge aesthetics in the twentieth century LAS The search for aesthetic understanding
  • p 1: BEAM " Early man had to devise ways to cross a stream and a deep gorge to survive. A boulder or two dropped into a shallow stream works well as a stepping stone, as many of us have discovered — but for deeper flowing streams, a tree dropped between banks is amore successful solution. So the primitive idea of a simple beam bridge was born."
  • p 1 SUSPENSION "In the forests of Peru today and the foothills of the Himalayas, crude rope bridges span deep gorges and fast-flowing streams to maintain pathways from village to village for hill tribes. Such primitive rope bridges evolved from the vine and creeper that early man would have used to swing through the forest and to cross a stream. Here is the second basic idea of a bridge — the suspension bridge."
  • p 1 BEAM "In this period [paleolithic] the simple log bridge had to serve many purposes. It needed to be broad and strong enough to take cattle, it needed to be level and a solid platform to transport food and other materials, and it needed to be movable so that it could be withdrawn to prevent their enemies from using it. Narrow tree trunk bridges were inadequate and were replaced by double log beams spaced wider apart on which short lengths of logs were placed and tied down to create a pathway. The pathways were"
  • p 2 COFFER DAM & PILINGS: "planed by sharp scraping tools or axes in the Bronze Age and any gaps between them plugged with branches and earth to create a level platform. For crossings over wide rivers, support piers were formed from piles of rocks in the stream. Sometimes stakes were driven into the riverbed to form a circle and then filled with stones creating a crude coffer dam. Around 4000BC, early Bronze Age ‘lake dwellers’ lived in timber houses built out over the lakes, in the area which is now Switzerland. To ensure their houses did not sink early humans evolved ways to drive timber piles into the lake bed. From the discovery of this came the timber pile and the trestle bridge."
  • p 2 POST & LINTEL BEAM: "So primitive bridges were essentially post and lintel structures, either made from timber or stone or a combination of both. Sometime later, the simple rope and bamboo suspension bridge was devised, which developed into the rope suspension bridges that are in regular use today in the mountain reaches of China, Peru, Columbia, India and Nepal."
  • p 2 ARCH (SUMERIA used BRICKS) "But it took man until 4000 BC to discover the secrets of arch construction. In the Tigris—Euphrates valley the Sumerians began building with adobe — a sun-dried mud brick — for their palaces, temples, ziggurats and city defences. Stone was not plentiful in this region and had to be imported from Persia, so was used sparingly. The brick module dictated the construction principles they employed, to scale any height and to bridge any span. And through trial and error it was the arch and the barrel vault that was devised to build their monuments and grand architecture at the peak of their civilization. The ruins of the magnificent barrel-vaulted brick roof at Ptsephon and the Ishtar Gate at Babylon, are a reminder of Mesopotamian skill and craftsmanship. By the end of Third Dynasty around 2475BC, the Egyptians had also mastered the arch and used it frequently in constructing relieving arches and passageways for their temples and pyramids."
  • p 2 WRITTEN RECORD OF BRIDGES "The earliest written record of a bridge appears to be a bridge built across the Euphrates around 600 BC as described by Herodotus, the fifth century Greek historian. The bridge linked the palaces of ancient Babylon on either side of the river. It had a hundred stone piers which supported wooden beams of cedar, cypress and palm to form a carriageway 35 ft wide and 600 ft long. Herodotus mentions that the floor of the bridge would be removed every at night as a precaution against invaders.
  • p 2-3 CHINA "In China it would appear that bridge building evolved at a faster pace than the ancient civilizations of Sumeria and Egypt. Records exist from the time of Emperor Yoa in 2300BC on the traditions of bridge building. Early Chinese bridges included pontoons or floating bridges and probably looked like the primitive pontoon bridges built in China today. Boats called sampans about 30 ft long were anchored side by side in the direction of the current and then bridged by a walkway. The other bridge forms were the simple post and lintel beam, the cantilever beam and rope suspension.... In later centuries Chinese bridge building was dominated by the arch, which they copied and adapted from the Middle East as they travelled the silk routes which opened during the Han Dynasty around 100 AD."
  • p 3 "Through Herodotus we learn about the Persian ruler Xerxes and the vast pontoon bridge he built, consisting of two parallel rows of 360 boats, tied to each other and to the bank and anchored to the bed of the Hellespont, which is the Dardanelles today. Xerxes wanted to get his army of two million men and horses to the other bank to meet the Greeks at Thermopohlae. It took seven days and seven nights to get the army across the river. Sadly for Xerxes, his massive army was defeated at the Battle of Thermophalae in 480 BC, the remnants of which retreated back over the pontoon bridge to fight another day. The Persians were great bridge builders and built many arch, cantilever and beam bridges. There is a bridge still standing in Khuzistan at Dizful over the river Diz which could date anywhere from 350BC to 400AD. The bridge consists of 20 voussoir arches which are slightly pointed and has a total length of 1250 ft. Above the level of the arch springing are small spandrel arches, semicircular in length, which gives the entire bridge an Islamic look, hence the uncertainty of it Persian origins."
  • p 3 ROMAN "The Romans on the other hand were the masters of practical building skills. They were a nation of builders who took arch construction to a science and high art form during their domination of Mediterranean Europe. Their influence on bridge building technology and architecture has been profound. They conquered the world as it was then know, built roadways, canals and cities that linked Europe to Asia and North Africa and produced the first true bridge engineers in the history of humankind. The Romans understood that the establishment and maintenance of their empire depended on efficient and permanent communications. Building roads and bridges was there ... "
  • p 4: ROMANS: STONE > WOOD "The Romans also realized, as did the Chinese in later centuries, that timber structures, particularly those embedded in water had a short life, were prone to decay, insect infestation and fire hazards. Prestigious buildings and important bridge structures were therefore built in stone. But the Romans had also learnt to preserve their timber structures by soaking timber in oil and resin as a protection against dry rot, and coating them with alum for fireproofing. They learnt that hardwood was more durable than softwoods, and that oak was best for substructure work in the ground, alder for piles in water; while fir, cypress and cedar were best for the superstructure above ground."
  • p 4 ROMANS: semi-circular arches "The Romans realized that voussoir (made from wedge-shaped stones) arches could span further than any unsupported stone beam, and would be more durable and robust than any other structure. They ought to have known because the early Roman settlers were Etruscans. Semi-circular arches were always built by the Romans, with the thrust from the arch going directly down on to the support pier. It meant that piers had to be large. If they were built"
  • p 5 ROMANS: COFFER DAMS & PUMPING: "ide enough at about one-third of the arch span, then any two piers could support an arch without shoring or propping from the sides. In this way it was possible to build a bridge from the shore to shore, a span at a time, without having to form the entire substructure across the river before starting the arches. They developed a method of constructing the foundation on the riverbed within a coffer dam or watertight dry enclosure, formed by a double ring of timber piles with clay packed into the gap between them to act as a water seal. The water inside the coffer dam was then pumped out and the foundation substructure was then built within it. The massive piers often restricted the width of the river channel, increasing the speed of flow past the piers and increasing the scour action. To counter this the piers were built with cutwaters, which were pointed to cleave the water so it would not scour the foundations."
  • P 5 ROMANS: TEMP WOOD FRAMEWORK: "The stone arch was built on a wooden framework built out from the piers and known as centring. The top surface was shaped to the exact semi-circular profile of the arch. Parallel arches of stones were placed side by side to create the full width of the roadway. The semi-circular arch meant that all the stones were cut identically and that no mortar was needed to bind them together once the keystone was locked into position. The compression forces in the arch ensured complete stability of the span. Of course, the Romans did build many timber bridges, but they have not stood the test of time and today all that remains of their achievement after 2000 years are a handful of stone bridges in Rome, and a few scattered examples in France, Spain, North Africa, Turkey and other former Roman colonies. But what still stands today, whether it is a bridge or an aqueduct, rank among the most inspiring and noble of bridge structures ever built, considering the limitations of their technology."
  • p 5: DARK AGES: CHURCH carried on ROmAN bridge skills: "It was the church who had preserved and developed both spiritual understanding and the practical knowledge of building during this period. And not surprisingly it was bridge building among the many skills and crafts that became associated with it."
  • p 7: RENAISSANCE: "Not since the days of Homer, Aristotle and Archimedes in Hellenistic times have such great feats of discovery in science and mathematics, and such works of art and architecture been achieved, as during the Renaissance. Modern science was born in this period through the enquiring genius of Copernicus, Da Vinci, Francis Bacon and Galileo and in art and architecture through Michelangelo, Brunellesci and Palladio. During the Renaissance there was a continual search for the truth, explanations of natural phenomena, greater self-awareness and rigorous analysis of Greek and Roman culture. As far as bridge building was concerned, particularly in Italy, it was regarded as a high art form. Much emphasis was placed on decorative order and pleasing proportions as well as the stability and permanence of its construction. Bridge design was architect-driven for the first time with Da Vinci, Palladio, Brunelleschi and even Michelangelo all experimenting with possibility of new bridge forms. The most significant contribution of the Renaissance was the invention of the truss system, developed by Palladio from the simple king post and queen post roof truss, and the founding of the science of structural analysis with the first book ever written on the subject by Galileo Galilei entitled ‘Dialoghi delle Nuove Scienze’ (Dialogues on the New Science) published in 1638."
  • p 7 Palladio "Palladio did not build many bridges in his lifetime, many of his truss bridge ideas were considered too daring and radical and his work lay forgotten until the eighteenth century. His great treatise published in 1520 Four Books of Architecture in which he applied four different truss systems for building bridges, was destined to influence bridge builders in future years when the truss replaced the arch as the principal form"
  • p 8-10 REN. BRIDGES: "Which bridge of the Renaissance is the most beautiful: Florence’s Santa Trinita, Venice’s Rialto or Paris’ Pont Neuf? Arguably the most famous and celebrated bridge of the Renaissance was the Rialto bridge designed by Antonio Da Ponte in Venice."
  • p 11: AGE OF REASON & 18th CENTURY: "In this period, masonry arch construction reached perfection, due to a momentous discovery by Perronet [viz: the perfection of the low, flat-arched stone bridge, using slender piers to create graceful, wide spans] and the innovative construction techniques of John Rennie. Just as the masonry arch reached its zenith 7000 years after the first crude corbelled arch in Mesopotamia, it was to be threatened by a new building material — iron — and the timber truss, as the principal construction for bridges in the future. This was the era when civil engineering as a profession was born, when the first school of engineering was established in Paris at the Ecole de Paris during the reign of Louis XV. The director of the school was Gabriel who had designed the Pont Royal. He was given the responsibility of collecting and assimilating all the scientific information and knowledge there was on the science and history of bridges, buildings, roads and canals. "
  • p 11 "Jean Perronet has been called the father of modern bridge engineering for his inventive genius and design of the greatest masonry arch bridges of the century. In his hands the masonry arch reached perfection. The arch he chose was the curve of a segment of a circle of larger radius, instead of the familiar three-centred arch. To express the slenderness of the arch he raised the haunch of the arch considerably above the piers. He was the first person to realize that the horizontal thrust of the arch was carried through the spans to the abutments and that the piers, in addition to the carrying the vertical load, also had to resist the difference between the thrusts of the adjacent spans. "
  • p 11 JOHN RENNIE & NEW LONDON BRIDGE "With France under the inspired leadership of Gabriel and then Perronet, the rest of Europe could only admire and copy these great advances in bridge building. In England, a young Scotsman, John Rennie, was making his mark following in the footsteps the great French engineers. He was regarded as the natural successor to Perronet, who was a very old man when Rennie started on his career. Rennie was a..... brilliant mathematician, a mechanical genius and pioneering civil engineer. In his early years he worked for James Watt to build the first steam-powered grinding mills at Abbey Mills in London, and later designed canals and drainage systems to drain the marshy fens of Lincolnshire. He built his first bridge in 1779 across the Tweed at Kelso. It was a modest affair with a pier width-to-span ratio of one to six with a conservative elliptical arch span. He picked up the theory of bridge design from textbooks and from studies and discussion about arches and voussoirs with his mentor Dr Robison of Edinburgh University. He designed bridges with a flat, level roadway and not the characteristic hump of most English bridges. It was radical departure from convention and was much admired by all the town’s people, farmers and traders who transported material and cattle across them. This bridge was a modest forerunner to the many famous bridges that Rennie went on to build: Waterloo, Southwark and New London Bridge. What then was Rennie’s contribution to bridge building? For Waterloo bridge, the centring for the arches was assembled on the shore then floated out on barges into position. So well and efficiently did this system work that the framework for each span could be put into position in a week. This was a fast erection speed and as a result Rennie was able to halve bridge construction time. So soundly were Rennie’s bridges built that 40 years later Waterloo bridge had settled only 5 in. Rennie’s semi-elliptical arches, sound engineering methods and rapid assembly technique, together with the Perronet segmental arch, divided pier and understanding of arch thrust, changed bridge design theory for all time."
  • P 12-15 WOOD BRIDGES (ESP. TRUSS) IN USA (not STONE) "The USA had no tradition or history of building with stone, and so early bridge builders used the most plentiful and economical materials that was available: timber. The Americans produced some of the most remarkable timber bridge structures ever seen, but they were not the first to pioneer such structures. The Grubenmann brothers of Switzerland were the first to design quasi-timber truss bridges in the eighteenth century. The Wettingen bridge over the Limmat just west of Zurich was considered their finest work. The bridge combines the arch and truss principle with seven oak beams bound close together to form a catenary arch to which a timber truss was fixed. The span of the Wettingen was 309 ft and far exceeded any other timber bridge span."
    • p 13-15 much discussion of truss varieties, etc
  • P 16: RAIL BRIDGES IN USA "With arrival of the railways in the USA, bridge building continued to develop along two separate ways. One school continued to evolve stronger and leaner timber truss structures, while the other experimented with cast iron and wrought iron, slowly replacing timber as the principal construction material."
  • p 16-17: 1800s: INVENTION OF STEEL & CONCRETE ENABLE MODERN BRIDGES "The industrial revolution which began in Britain at the end of the eighteenth century, gradually spread and brought with it huge changes in all aspects of everyday life. New forms of bulk transportation, by canal and rail, were developed to keep pace with the increasing exploitation of coal and the manufacture of textiles and pottery. Coal fuelled the hot furnaces to provide the high temperatures to smelt iron. Henry Bessemer invented a method to produce crude steel alloy by blowing hot air over smelted iron. Seimens and Martins refined this process further to produce the low carbon steels of today. High temperature was also essential in the production of cement which Joseph Aspdin discovered by burning limestone and clay on his kitchen stove in Leeds in 1824. Wood and stone were gradually replaced by cast iron and wrought iron construction, which in turn was replaced by first steel and then concrete; the two primary materials of bridge building in the twentieth century"
  • p 17: CAST IRON & WROUGHT IRON: "The age of iron (1775-1880) Of all the materials used in bridge construction — stone, wood, brick, steel and concrete — iron was used for the shortest time. Cast iron was first smelted from iron ore successfully by Dud Dudley in 1619. It was another century before Abraham Derby devised a method to economically smelt iron in large quantities. However, the brittle quality of cast iron made it only safe to use in compression in the form of an arch. Wrought iron, which replaced cast iron many years later, was a ductile material that could carry tension. It was produced in large quantities after 1783 when Henry Cort developed a puddling furnace process to drive impurities out of pig iron. ."
    • CAUTION: I cannot assume all "iron" is cast iron: wrought iron was also commonly used & was not as brittle.
  • p 18-19: STEEL "Steel is a refined iron where carbon and other impurities are driven off. Techniques for making steel are said to have been known in China in 200BC and in India in S00BC. But the process was very slow and laborious and after a great deal of time and energy only minute amounts were produced. It was very expensive, so it was only used for edging tools and weapons until the nineteenth century. In 1856, Henry Bessemer developed a process for bulk steel production by blowing air through molten iron to burn off the impurities. It was followed by the open hearth method patented by Charles Siemens and Pierre Emile Martins in Birmingham, England in 1867, which is the basis for modern steel manufacture today. It took a while for steel to supersede iron, because it was expensive to manufacture. But when the world price of steel dropped by 75% in 1880, it suddenly was competitive with iron. It had vastly superior qualities, both in compression and tension — it was ductile and not brittle, and much stronger ..."
  • p 21 STEEL TRUSS (ESP USA) "When the steel prices dropped in the 1870s and 1880s the first important bridges to use steel were all in the USA. The arches of St Louis Bridge over the Mississippi and the five Whipple trusses of the Glasgow Bridge over the Missouri, were the first to incorporate steel in truss construction. St Louis, situated on the Mississippi and near the confluence of the Missouri and Mississippi was the most important town in midwest USA, and the focal point of north-south river traffic and east-west overland routes."
  • P 21-22 CANTILEVER BRIDGE (HE CALLS IT "CANTILEVER TRUSS")
    • " Arch bridges had been constructed for many centuries in stone, then iron, and steel when it became available. Steel made it possible to build longer span trusses than cast iron without any increase in the dead weight. Consequently it made cantilever long-span truss construction viable over wide estuaries. The first and most significant cantilever truss bridge to be built was the rail bridge over the Firth of Forth near Edinburgh, Scotland in 1890. The cantilever truss was rapidly adopted for the building of many US railroad bridges until the collapse of the Quebec Bridge in 1907."
  • p 22: SUSPENSION BRIDGES " The early pioneers of chain suspension bridges were James Finlay, Thomas Telford, Samuel Brown and Marc Seguin, but they had only cast and wrought iron available in the building of their early suspension bridges. It was not until Charles Ellet’s Wheeling Bridge had shown the potential of wire suspension using wrought iron that the concept was universally adopted. Undoubtedly the greatest exponent of early wire suspension construction and strand spinning technology was John Roebling. His Brooklyn Bridge was the first to use steel for the wires of suspension cables. Suspension bridges are capable of huge spans, bridging wide river estuaries and deep valleys and have been essential in establishing road networks across a country. They have held the record for longest span almost unchallenged from 1826 to the present day and only interrupted between 1890 to 1928, when the cantilever truss held the record."
    • NOTE that many suspension bridges were built before Brooklyn bridge, but it was first to use wire-steel for cables!!
  • p 239 (yes, 239): Catenary of an un-loaded hanging cable becomes a parabola when bridge deck is suspended from it by tie-wires. [this is from a different chapter in the book, and has a differnt author, not David Bennett]
  • p 24: Steel plate girder and box girder - "Since the development of steel and the I-beam, many beam bridges were built using a group of beams in parallel which were interconnected at the top to form a roadway. They were quick to assemble but they were only practical over relatively short spans for rail and road viaducts. The riveted girder I-beam was later superseded by the welded and friction grip bolted beam. However, relatively long spans were not efficient as the depth of the beam could become excessive. To counter this, web plate stiffeners were added at close intervals to prevent buckling of the beam. Another solution was to make the beam into a hollow box which was very rigid. In this way the depth of the beam could be reduced and material could be saved. The steel box girder beams could be quickly fabricated and were easy to transport. Their relatively shallow depth meant that high approaches were not necessary. Most of this pioneering work was carried out during and after the second world war when there was a huge demand for fast and efficient bridge building for spans of up to 1000 ft. The major rebuilding programme in Germany witnessed the construction of many steel box girder and concrete box girder bridges in the 1950s and 1960s. For spans greater than 1,000 ft the suspension and cable stay bridge are generally more economical to construct.
    • NOTE MENTION above of "concrete box girder bridges in the 1950s and 1960s"
  • p 24-25: FAILURE ANALYSIS: STeel box girders "In the 1970s the world’s attention was focused on the collapse of four steel box girder bridges under construction. The four bridges were in Vienna over the Danube, in Milford Haven in Wales when four people were killed, a bridge over the Rhine in Germany and the West Gate bridge in Melbourne over the Lower Yarra River. By far the worst collapse was on the West Gate bridge, a single cable stay structure with a continuous box girder deck. A deck span section 200 ft long and weighing 1200 tons, buckled and crashed off the pier support on to some site huts below, where workmen and engineers were having their lunch. Thirty-five people were killed in the tragedy. After this accident, further construction of steel box girder deck bridges was halted until better design standards, new site checking procedures and a fabrication specification was agreed internationally."
  • p 25: CONCRETE (esp CONCRETE ARCH): - Although engineers took longer to realize the true potential of concrete as a building material, today it is used everywhere in a vast number of bridges and building applications. Concrete is a brittle material, like stone, good in compression, but not in tension so if it starts to bend or twist it will crack. Concrete has to be reinforced with steel to give it ductility, so naturally its emergence followed the development of steel. In 1824 Joseph Aspdin made a crude cement from burning a mixture of clay and limestone at high temperature. The clinker that was formed was ground into a powder, and when this was mixed with water it reacted chemically to harden back into a rock. Cement is combined with sand, stones and water to create concrete, which remains fluid and plastic for a period of time, before it begins to set and hardens. It can be poured and placed into moulds or forms while it is fluid, to create bridge beams, arch spans, support piers — in fact a variety of structural shapes. This gives concrete special qualities as a material, and scope for bold and imaginative bridge ideas.
  • P: 26: CONCRETE USED FOR WORLDS LONGEST multi-span BRIDGES: "Concrete has been used in building most of the world’s longest bridges. The relative cheapness of concrete compared to steel, the ability to rapidly precast or form prestressed beams of standard lengths, has made concrete economically attractive. Lake Ponchetrain Bridge, a precast concrete segmental box girder bridge, in Louisiana is the longest bridge in the US with an overall length at 23 miles."
  • p 26: HIGHWAY BRIDGES - MOST(?) use CONCRETE BOX GIRDER (beam) "1950s—60s Many motorway bridges and viaducts were built in Europe and USA using concrete box girder construction. Some were precast segmental construction, some were cast in place."
  • p 27-28 CABLE STAYS "Cable stays are an adaptation of the early rope bridges, and guy ropes for securing tent structures and the masts of sailing ships. When very rigid, trapezoidal box girder bridge decks were developed for suspension bridges, it allowed a single plane of stays to support the bridge deck directly. This meant that fewer cables were needed than a conventional suspension system, there was no need for anchorages and therefore it was cheaper to construct. Cost and time have always been the principal motivators for change and innovation in the bridge engineering."
      • NOTE: Brooklyn bridge already used cable stays in addition to parabola + ties; evolution by removing the parabola & ties. : Cheaper, faster; Easier
  • p 28 HISTORY OF CABLE STAYS "The first modern cable stay bridges were pioneered by German engineers just after the second world war, led by Fritz Leonhardt, Rene Walter and Jorge Schlaich. The cable stay bridge is probably the most visually pleasing of all modern long span bridge forms. In recent times the development of the cable stay and box girder bridge deck has continued with the work of Swedish engineers COWI consult; bridge engineers Carlos Fernandez Casado of Spain; R Greisch of Belgium; Jean Muller International, Sogelerg, and Michel Virloguex of France."'
  • p 29-30 : AESTHETICS "s it possible there is a universal law or truth about beauty on which we can all agree? We can probably argue that no matter what out aesthetic taste in art, literature or music, certain works have been universally acclaimed as masterpieces because they please the senses, evoke admiration and a feeling of well-being. Music, literature and painting can appeal to an audience directly, unlike a building or bridge whose beauty has to be ‘read’ through its structural form, which has been designed to serve another more fundamental purpose. Judging what is great from many competent examples must come from an individual’s own experience and understanding of past and contemporary styles of expression. The desire to please or to shock is not fundamental in the design of bridges whose primary purpose is to provide a safe passage over an obstacle, be it a river or gorge or another road way. A bridge taken in it purest sense is no more than an extension of a pathway, a roadway or a canal. We do not regard roads, paths and canals as ‘art forms’ that evoke aesthetic pleasure as we do with buildings. Hence, it is reasonable to ask why should a bridge be an art form? In the very early years of civilization, bridges were built to breach a chasm or stream to satisfy just that purpose. They had no aesthetic function. Later on when great civilizations placed a temporal value on the quality of their buildings and heightened their religious and cultural beliefs through their architecture, these values transferred to bridges. And like all the important buildings of a period, when stone and timber were the principal sources of construction material, work was done by skilled craftsmen. Masons would cut, chisel and hew stones: carpenters would saw, plane and connect pieces of timber falsework or centring to support the masonry structure. It took many years to ‘fashion’ a bridge. Each stone was carefully cut to fit precisely into position. Hundreds of stone masons would be employed to work on the important bridges. Voussoirs and key stones were sculptured and tooled in the architectural style of the period. Architecture was regarded as an integral part of bridge construction and this tradition continued into the age of iron, where highly decorative wrought iron and cast iron sections were expressed on the external faces of the bridge. Well into the middle of the twentieth century arch bridges in concrete and steel were cloaked in masonry panels to imitate the Renaissance, Classical and Baroque periods.
  • P 30 AESTHETICS VS SPEED/COST "But gradually as the pace of industrial change intensified, by the expansion of the railways, and by the building of road networks, a radical step change in the design and construction of bridges occurred. Bridges had to be functional, they had to be quick to build, low in cost, and structurally efficient. They had to span further and use fewer materials in construction. Less excavation for deep piers and foundations underwater meant faster construction, whereas short continuous trestle supports across a wide valley were simple to construct and required shallow foundations. Under these pressures, standardization and prefabrication of bridges displaced aesthetic consideration in bridge design. Of course, there were exceptions when prestigious bridges were commissioned in major commercial centres to retain the quality and character of the built environment. And sometimes even these considerations were sidelined in the name of progress and regeneration, as was the case in the aftermath of the two world wars. When economic stability returns to a nation after the ravages of war, and living standards start to rise, so does interest in the arts and quality of the built environment. After the second world war, for example, rebuilding activity had to be fast and efficient, with great emphasis placed on prefabrication, system-built housing and the tower block to re-house as many people as possible. In Germany rebuilding the many bridges that were demolished, led to the development of the plate girder and box girder structure. Box girder bridge structures with standardized sections, prolifera "
  • P 31 AESTHETICS IN 21ST CENTRUIY "Over the centuries as the various forms of bridges evolved in the major towns and cities, the architectural style of the period was superimposed on them, to create order and homogeneity. Classical, Romanesque, Byzantine, Isiamic, Renaissance, Gothic, Baroque, Georgian and Victorian architectural styles adorn many historic bridges today, such as the Renaissance Rialto Bridge in Venice, the Romanesque Pont Saint Angelo in Rome, the French Gothic of the Pont de la Concorde in Paris. They are recognizable symbols of an era, of imperialist ambition and nationhood, where the dominant form of construction was the arch. But with the arrival of steel and concrete in the early part of the twentieth century, new structural forms emerged in building and bridge design that radically changed both the architecture and visual expression of bridges. The segmental arch was replaced by the flat arch, the flat plate girder and box girder beam; the cantilever truss was replaced by the cable stay and the suspension bridge. The decorative stone-clad bridges of the past were slowly replaced by the minimalism of highly engineered structures."
  • p 32: BEAUTY TAKES BACK SEAT IN 20th CENTRY: "Although bridge design was dominated by civil engineers in the twentieth century, somehow the aesthetic vision of the early pioneer’s such as Roebling, Eiffel and Maillart and later by Steinman, McCullough et al., was never seriously addressed in contemporary bridge design in the UK during the middle to later half of the twentieth century. Education and training of British civil engineers it appears, generally did not include one iota of understanding on the architecture of the built environment.
  • P 39 AESTHETICS "The growing trend today [1999-2000] is to appoint a team of designers from partnerships between engineers and architects to ensure that aesthetics in design is fully considered. This is a healthy sign. The LDDC successfully forged partnerships between architects and engineers in the design of a series of innovative and creative footbridges that are sited in London’s Docklands. Architects like the Percy Thomas Partnership, Sir Norman Foster & Partners, Leifschutz Davidson and Chris Wilkinson in particular, have made the transfer from building architecture to bridge architecture effortlessly. In France, the architect Alain Speilman has specialized in bridge architecture for nearly 30 years, and has worked with many of France’s leading bridge consultants and been involved in the design of over 40 bridge schemes. He is following a..."
  • p 40 AESTHETICS "Civic pride has over the centuries compelled governments and local highway authorities to attempt to build pleasing bridges in our cities and important towns in order to maintain the quality of the built environment. We all agree that the linking of places via bridges symbolizes co-operation, communication and continuity and that the bridge is one of the most important structures to be built. It is the modest span bridges over motorways, across canals and waterways in built-up urban areas that are most devoid of any sensitivity with their surroundings — the built environment and the urban fabric of our community. These featureless structures are in such profusion — plate girder bridge decks carrying trains over a busy high street and dirt-stained urban motorway overbridges — that they are the only bridges most of see as we journey through a town or a city. The cause of this blight stems largely from legislative doctrine on bridge design imposed by highway authorities, whose remit is to ensure that the design conforms to a set of rules on how it should perform and how little it will cost. It encourages the mediocre, the mundane and unimaginative design to be passed as ‘fit for purpose’. What can be done to improve things? The way forward has already been shown by the footbridges commissioned by LDDC in the UK, by the bridges built by Caltrans along the west coast of the USA in the 1960s, by the bridges built by the Oregon Highways Department in the 1930s and 1940s and the bridges commissioned by SETRA in France in the 1980s, for example along the A75 Clermont-— Ferrand highway. So it can be done."
  • p 40-41 VITRUVIUS & AESTEHTICS "Vitruvius identified three basic components of good architecture as firmness, commodity and delight. Many subsequent theorists have proposed different systems or arguments by which the quality of architecture can be analysed and their meaning understood. The tenets Vitruvius identified provides a simple and valid basis for judging the quality of buildings and bridge structures today. ‘Firmness’ is the most basic quality a bridge must posses and relates to the structural integrity of the design, the choice of material, and the durability of the construction. ‘Commodity’ refers to the function of the bridge, and how it serves the purpose for which it was designed. This quality is rarely lacking in any bridge design, whether it is ugly or good to look at. ‘Delight’ is the term for the effect of the bridge on the aesthetic sensibilities for those who come in contact with it. It may arise from the chosen shape and form of the bridge, the proportion of the span to the pier supports, the rhythm of the span spacing and how well the whole structure fits in with the surrounding environment. It is the component that is most lacking in bridges built in the middle half of this century."

Dan Cruikshank 2010 Bridges: Designs that Changed the World

[edit]
  • p 8-55: INTRO
    • DONE p 8-9 "From earliest times, mankind has built bridges, and still today bridge construction remains heroic, the most absolute expression of the beauty and excitement invoked by man-made constructions that are practical, functional, and fit for their purpose. Bridges that are leaps of faith and imagination, that pioneer new ideas and new materials, that appear both bold and minimal when set in the context of the raw natural power they seek to tame, are among the most moving objects ever made by man. They are an act of creation that challenge the gods, works that possess the very power of nature itself. They are objects in which beauty is the direct result of functional excellence, conceptual elegance and boldness of design and construction. Like most people, I am addicted to bridges — to their raw, visceral punch, to their often astonishing scale and audacity, enthralled by their ability to transform a place and community and amazed by the way a bold bridge can make its mark on the landscape and in men’s minds, capture the imagination, engender pride and sense of identity and define a time and place. A great bridge — one that defies and tames nature — becomes almost in itself a supreme work of nature. Bridges embody the essence of mankind’s structural ingenuity ... with dramatic clarity"
    • DONE p 9 "The most thrilling bridges are, in many ways, those not enhanced by superficial or extraneous ornament or cultural references. What moves and impresses is their honest expression of the materials and means of construction — their only ornament is a direct result of the way in which they are built and perform. A great bridge has an emotional impact, it has a sublime quality and a heroic beauty that moves even those who are not accustomed to having their senses inflamed by the visual arts. Bridges are a great paradox, they not only use nature against nature, but magically the best examples do not defeat or damage nature but enhance it, and, in ways that are sometimes hard to fathom, achieve a deep harmony with their surroundings. For these reasons bridges have captured the imagination of people through the ages and now they are the only large-scale and radical examples of modern design and construction that the public generally applaud. All can see that bridges stand for something most significant, for the indomitable human spirit, the love of daring and of challenge, the power of invention."
    • DONE p 11 "For all these reasons bridges have been applauded as heroic, sacred — almost mystic — works by all cultures. Bridges of great scale or span were venerated in Medieval Europe, either as pious works that glorified God or as almost impossible acts of daring that could only have been achieved with the aid of the Devil (see page 94). Great bridges were, people assumed, creations that could only be completed through prayer and divine guidance or by the sale of the soul to dark forces. They were places where you could meet angels and saints as if conducting you to Heaven, or the Devil himself collecting his toll."
    • DONE p 11-12 CHINA " Similarly in China: the truly remarkable Zhaozhou orAnji Bridge in Hebei province, built between 595 and 605 AD to the designs of Li Chun and the world’s oldest open-spandrel [== air gaps/triangles between arch and deck; not solid] segmental arched masonry bridge, is particularly rich in myth, legend and stories of the supernatural. This is mainly because its construction methods and ambitious scale — its main arch of segmental forms spans a mighty 37.7 metres — astonished most contemporary observers. .... achieved the wide span by using 28 parallel and abutting arches, each formed with massive, precisely cut and wedged limestone voussoirs whose joints were strengthened with wrought-iron cramps or bars."
    • DONE p 13 ART & METAPHOR: "Always bridges have been seen as things of breathtaking, elemental beauty, as audacious and epic engines of transformation. The profound role that bridges play, in all their symbolical and metaphoric richness, in our imaginations is revealed — and confirmed — by the works of poets, painters and writers. Shortly before the Humber Bridge in England opened in 1981 — a huge and daring suspension bridge whose span of 1,410 metres was until 1997 the widest in the world — Philip Larkin wrote a poem about the arrival of this new creation near his home town ,..."
    • DONE P 14-16 ART & PAINTERS "Many painters, for reasons never fully explained, have not only included bridges in their works as seemingly peripheral objects, but have at times become obsessed by them, or by their apparent meanings. Indeed, for some artists, bridges have become veritable muses, objects that unleash the creative force of the imagination. In the romantically rude but also idyllic landscape that enfolds behind the Mona Lisa there is a bridge. It has several arches that appear semi-circular in form. It could be Roman. Why did Leonardo da Vinci include a bridge in this particular portrait? There are any number of possible answers, the least acceptable of which is that he was merely reproducing a landscape and details with which he was familiar, painting what he saw. The pioneering technique he used to render the landscape — depth is implied by the use of paler, misty-looking colours and by a softening of detail — gives all a naturalism and realism. But this is clearly a fictitious and unreal landscape and one pregnant with deep meaning — but what meaning? ..."
    • DONE P 17-19 IN LITERATURE: "It is not just poets and painters who have viewed bridges as potent symbols and metaphors. So have novelists. For example Thornton Wilder, in The Bridge of San Luis Rey, .... Perhaps the most relentless literary pursuit of the bridge as symbol is Ivo Andric’s The Bridge on the Drina, a novel published in 1945 and inspired by Bosnia’s history and quest for independence and identity. The novel focuses on the town of Visegrad and the Mehmed PaSa Sokolovié Bridge over the Drina river and spans 400 years from the time the region, town and river were dominated first by the Muslim Ottoman Turks and then by the Christian Austro-Hungarian Empire. It chronicles the religious battles between the communities that co-existed in a border town on a river forming a frontier between different peoples — and the thread that holds the narrative together and that weaves through time is the bridge."
    • DONE P 32: Galileo Gallilei - ENGIENERInG "Crucial to this new understanding was the groundbreaking research and analysis undertaken in the late sixteenth and early seventeenth centuries by mathematician, astronomer and philosopher Galileo Galilei. This allowed late Renaissance engineers to calculate the ways in which the shape and size of structural members — for example beams and trusses — and the materials from which they were made would affect their ability to carry and transmit loads. Significantly Galileo identified the ‘scaling problem’.
    • DONE p 33 EARLY BOOKS "In the late sixteenth century the scientific and mathematical approach to construction was in fact being explored by many and evolved at a rapid rate. For example, the architect Andrea Palladio’s I quattro libri dell'architettura of 1570 included the first published illustration of a triangulated truss — a robust structure for transferring loads through a rigid system of triangular forms. Other important publications pioneering, promoting or explaining theories of bridge construction included Machinae Novae of 1595 by Fausto Veranzio, which includes information on tied-arch bridge construction, the oval lenticular or lentil-shaped truss, and the iron chain-link suspension bridge. A key later work containing much technical information is Traztre des Ponts..."
    • DONEP 33 PERMUTATTIONS: "The permutations of materials and structural principles employed in bridge construction are seemingly many, varied and complex — timber, brick, stone, cast and wrought iron, steel, hydraulic cement, mass concrete and steel-reinforced concrete, arches of diverse form, beams, cantilevers, pylons, cables and masts. But in its aim bridge construction is straightforward and construction simple. The object is to link two points of land as safely and efficiently as possible. If the obstacle being bridged is running water, then the ideal is to achieve wide spans with minimal support rising from the water to make the bridge easier to build and maintain, to avoid disturbing navigation, and to reduce the risk of the bridge being swept away..."
    • DONE P 34: DEAD VS LIVE LOAD "In essence bridge construction is of two basic types. The carriageway — be it for vehicles or pedestrians — is either supported from below or suspended from above. If the ‘dead’ load of the carriageway (its weight) and the ‘live’ load of the carriageway (the weight of the use it carries plus the ‘environmental load’ comprising the weight and pressure of rain, snow and wind) are supported from below it must be carried on arches or vaults of varied types; on beams either cantilevered from, or supported by, abutments and piers; or set within a lattice-like engineered truss wrought of timber or metal.
    • p 34: NATURAL BRIDGES: There are two models of nature for support from below: rock formations that arch over; and timber logs or beams laid across, chasms or rivers."
    • DONE p 35 COMPRESSION & TENSION: "act on bridges, either singly or in combination: tension, or a tendency to stretch or pull apart; compression which pushes together and compacts; shear, which is a sliding force; and torsion which is a twisting force." The form of the bridge, and the materials used in its construction, also create different — and utilize different — structural forces."
    • DONE P 36: HYBRID/COMPOSITE BRIDGES: COMBINE 2 or MORE BASIC STRUCTURES: "These basic strategies can be combined to create composite structures in which different members are acting under both compression and tension. For example, the cantilever bridge is a more complex version of the beam bridge, utilizing additional structural principles. The Forth Railway Bridge of the 1880s in Scotland is a useful illustration (see page 294). It incorporates massive steel lattice-work pylon towers, forming projecting ‘arms’ that are, in effect, huge balanced cantilevers linked by suspended spans ..."
    • P 37-38 BOW-STRING TRUSS
    • p 38 CHOICE OF STRUCTURE: "The choice of form chosen for the bridge usually depends on a number of factors: on the width, height and type of obstacle to be bridged; on the function of the bridge and estimated forces of ‘dead’ and ‘live’ loads; on time and materials available for use (masonry and cast-iron were really only appropriate for compression structures while more flexible or ‘elastic’ timber, wrought-iron or steel worked for tensile structures); and — of course — on the skill, knowledge, intentions and nerve of the bridge builder.."
    • p 39-55 MATERIALS
      • P 39-45 TIMBER & COVERED BRIDGES
      • p 46-47 : TRESTLES & VIADUCTS (esp wood?)
      • p 47-50  : MASONRY (STONE & BRICK); ARCHES etc
      • p 50-54 METAL (CAST IRON, STEEL, SUSPENSION, CABLE .)
  • DONEp 56-81 CHAPTER: EMPIRE (Roman)
    • p 58 "ROME, MORE THAN ANY EARTHLY POWER BEFORE or since, expressed its might and its aspirations through architecture and engineering. It took the architecture of the past — of the Egyptians, the Greeks and the Etruscans — and transformed it to suit its own needs and to realize the demands of its growing empire. New functions such" [as roads and water transportation led to the rapid development of things such as rounded arches and concrete led to spectacular advances]
    • p 59-60 " [these roman bridges embodied ] architectural virtues identified by the Roman architect Vitruvius over 2,000 years ago — ‘commodity, firmness and delight’ — by which he meant an architecture that simultaneously fulfils its functional requirements and is stable, while also being poetic and imbued with a power to inflame and engage the intellect."
    • P 60 ROmans experts in architecture: "This fascinating combination of characteristics is perhaps best expressed by the bridges and aqueducts that Rome created throughout its empire. Their roles as routes of communication and the means of supply were of vital importance to the well-being of the Roman world. Aqueducts brought a plentiful supply of water — essential for the Roman concept of civilized life — and roads transported goods and luxuries over great distances, allowed wealth creation through trade, and security through speedy troop movements. In addition to being functional objects, bridges and aqueducts were also intended, in their design and solidity, to express Rome’s cultural aspirations and the longevity of its vision. Together, these intentions produced structures of intense beauty — a beauty that comes from the pure and powerful realization of functional demands and of the way in which the potential of available building material can be enhanced through design."
    • P 60 "A remarkably large number of Roman bridges survive, in whole or in part, still fulfilling their original function within the former empire. They continue to astonish, inspire and delight, through their scale, fitness for purpose and often daunting engineering boldness. But there are four Roman bridges that haunt my imagination. They epitomize Roman engineering genius, in which sublime and utterly moving beauty is achieved by the almost ruthless observance of function. They are the essence of engineering, and also the essence of architecture at its best. There is little about their design and construction that is superfluous to function or to pertinent meaning. Their stones carry messages .... All of these structures lie outside of Italy. Two of them, the Pont du Gard in southern France near Nimes and the aqueduct of Segovia in Spain, carried the very life-blood of Roman civilization: abundant water. The others, the Alcantara Bridge over the River Tagus in Spain, and the Pont Flavien, in Saint-Chamas, Bouches-du-Rhone, France, seem to have served a largely military, strategic and triumphal purpose marking the omnipotent presence and power of Rome. But each one, in its solidity and scale, seems to have been built in defiance of nature. And yet this is not quite so, for it is the essential paradox of engineering that the violence of the forces of nature can only be withstood by man-made structures that fully utilize the forces of nature. The fact that these structures survive after 2,000 years or so — with all significant damage being the work of man and not natural forces —- demonstrates most succinctly how well these Roman engineers understood their work."
  • DONE p 82- 117 CHAPTER: PIETY and POLTICS
    • p 84: CAHORS BRIDGE (NO ITNRO?) "IN MEDIEVAL CHRISTIAN EUROPE, BRIDGES WERE built as pious works pleasing to God, as things of utility and of beauty, as part of the defence system, and of course, as routes of trade or conquest. The early fourteenth century Pont de Valentré, across the River Lot at Cahors is all of these ... It was utterly entrancing and, with its mesmerizing silhouette of tall pyramidal-topped towers and pointed arches, it seemed to sum up so many of the architectural and engineering aspirations and achievements of the age in which it was built. The twelfth and thirteenth centuries marked the great age of masonry-built bridges in the medieval Kingdom of France and in the English possessions in Aquitaine and Gascony. In the late twelfth century, almost the entire western half of France, from the English Channel to the Pyrenees was .."
    • p 86 CAHORS BRIDGE "This was a time before the modern concepts of European nationalism were forged. The Plantagenets were a branch of the French Angevin dynasty, and the English royal court was an outpost of French culture. As well as being the King of England, Henry was also the Duke of Normandy and Gascony, and Count of Anjou, Maine and Nantes. Indeed in this feudal world, popular allegiances and identity lay with the regions, rather than with the larger world or the kingdom of which the duchies or counties formed part. The complex balance of power and land ownership in France fluctuated constantly, and by the time the bridge at ..."
    • p 88 AVIGNON BRIDGE "The Pont Saint-Bénezet at Avignon had a near mythic origin that reveals the sacred nature of bridges in the medieval mind. They were seen as examples of the way in which the righteous and religious-minded could — with divine support and blessings — harness nature and command the elements. As with the Paradise Gardens of Islam (see page 118), bridges were, to medieval Christians, a means of realizing heaven on earth, of creating beauty, wealth and harmony. They were works that were pleasing to God and links not just between places on earth, but between this world and the next. In addition, bridges had an even deeper meaning for medieval Christians. In their faith, water was an important agent of transformation from the material to the spiritual. At baptism, holy water washes away sins and is part of the ritual of initiation into the Christian Church. Christ himself, perceived by Christians as the Son of God, had at his own request been baptized in the River Jordan and this action had pleased God (Matthew 13: 1-3). Given water and rivers are central to the Christian faith, so too is the means by which they are bridged"
    • p 89 AVIGNON: "Repeatedly in medieval France, clerics aided the construction of bridges in the same way that they aided the construction of churches and charitable institutions. In Toulouse, a testament of 1251 stated that money should be left to ‘churches and hospitals and bridges and other pious and poor places’, while in 1308, the year the bridge at Cahors was started, Pope Clement V granted for seven years an indulgence of 100 days ‘to those faithful who, truly penitent and confessed, stretched forth a helping hand to the fabric of the bridge the Dominicans were building near Nimes’.”? So in certain circumstances, donating money towards the construction of a bridge was deemed to be a worldly action that would reverberate through the afterlife. It was a noble deed that would reduce the time that, after death, the soul would have to suffer in purgatory. In this way, it was equal to making donations to churches and to charities or to founding hospitals, almshouses or colleges. The origin of the bridge at Avignon reflects the spiritual purpose of bridge construction, or so it is alleged. In the mid-twelfth century, a young shepherd named Bénézet is said to have had a vision in which God directed him to go to Avignon and inspire the building of a bridge across the dauntingly wide Rhone. The enterprise seems to have taken on the characteristics of a battle between good and evil, God and the Devil. ..."
    • p 96: Bridge at Orleans
    • p 112-114: " In France there is the twelfth century Pont du Diable at Olargues, Hérault and the fourteenth-century Pont du Diable at Céret, Pyrénées-Orientales. Both these are relatively small, stone-built bridges, nonetheless incorporating at least one arch of impressive span (that of Céret includes a majestic semi-circle that spans over 45 metres). The widest of these medieval single-arch prodigy bridges was that at VielleBrioude that had been started in about 1340 and crossed the Allier in a single 54.2 metre span. When it collapsed in 1822 it was believed to be the largest arch in the world. In Italy, Borgo a Mazzano near Lucca, possesses a stone-built fourteenth-century bridge that serves the ancient pilgrimage... [the bridge in Ceret was called the "Devil's Bridge" ] ... a fourteenth century bridge whose astonishing 45 metre span convinced many that it could only be the work of the Devil. It is one of many structurally daring medieval bridges in Europe for which the Devil was assumed to have been the chief engineer."
  • p 118-141 CHAPTER: Bridges of PARADISE [ISLAM, IRAN, etc] NO INTRO?
    • NOthing important in this chapter: the author simply likes this city
    • P 129 " Isfahan contains three important early bridges, and this number is probably not just a result of practical demands. In Islam three is a very significant number, for it is thought to display resolve and determination. Many important things, such as ablutions before prayers, are done three times, and sand or earth is thrown on a grave three times. One of the Hadiths states that God loves odd numbers, so three bridges probably has a powerful symbolic significance. Not all the bridges were completed during Shah Abbas’s lifetime, although all were probably conceived by him, and certainly all form part of his visionary city.... The bridge that was completed in his lifetime is the Bridge of Allahverdi Khan that crosses the Zayandeh Rub (river) as a continuation of the Chahar Bagh, the principle street of the city. Named after the general who was in charge of its construction, it’s also called the Bridge of Thirty-Three Arches (or Si-O-Se Pol). It is 14 metres wide and 160 metres long. The second bridge — Bridge of the Khaju (or Pole-iKhaju) — was built in 1650 by Shah Abbas IT, while the 146-metre-long third bridge — the Bridge of the Canal"
  • DONE p 142- 175 CHAPTER: Inhabited Bridges
    • p 144 "AS LONG AS BRIDGES HAVE BEEN BUILT THERE HAS been the desire to inhabit them. They have been the locations of shrines, chapels and fortifications but also of houses, shops and factories. Bridges are, after all, tempting slices of man-made real estate, perched conveniently over running water."
    • P 144-145 LONDON BRIDGE (1209–1831) "The great example is Old London Bridge, burned into popular imagination by the catastrophe of the Great Fire of 1666. It was constructed first out of timber on piled foundations in AD 55 by Roman engineers, then rebuilt on numerous occasions in timber, and from 1176 in stone — a mighty work that was as much an act of veneration to God as a functional structure (see page 148). From this time onwards London Bridge developed a history peculiar to itself. It had its own identity, trades, urban customs, and, with gates at either end, was a secure and self-contained town within the City. Indeed it had its own particular purpose, forming the gate into London from the south and the gate out of London for those heading [to Canterbury] .. It would also cater for the pilgrims en route to Canterbury, most of whom were members of the immensely popular cult of the recently martyred and canonized Archbishop Thomas Becket. Becket was a determined defender of the rights and privileges of the Catholic Church from royal interference. "
    • p 148 LONDON BRIDGE: "During the reign of King John, from 1199 to 1216, money was made directly from and for the bridge — essential for its regular maintenance — by granting licences for the construction upon it of houses and shops. Building upon the bridge became a great money-maker for the City’s Bridge House Estate, which from its foundation in 1284 grew vastly wealthy over the centuries from revenues and rents. With dense rows of tall houses — many of prodigious design cantilevering far out over the swirling waters — London Bridge also entered the realm of myth and lore as the world’s greatest inhabited bridge."
    • p 149 PONTE VECCHIO "The Ponte Vecchio surely possesses only a shadow of the splendour, and certainly the scale, of Old London Bridge. Nevertheless, it is a remarkable thing. It was built around 1345, perhaps to the designs of the painter Taddeo Gaddi, and crosses the River Arno with three handsome segmental arches — the widest of which has a span of 30 metres and the others 27 metres each."
  • p 176-223 CHAPTER: Forging the Railway Age
    • NO INTRO :-( ...entire chapter mostly focuses on Newscastle High Level Bridge, River Tyne
    • P 177 - 190 talks about the histgory of Newcastle city,
    • p 188 Newcastle "The High Level Bridge that was opened in 1849, has a total length of 407.8 metres (1,337 feet), and pioneered the idea of two tier bridges — an idea later developed in most spectacular fashion through a series of New York bridges, starting with the Queensboro Bridge that was completed in 1909 (see page 304). The top level of the bridge was to accommodate trains while the lower, covered, level was for road transport and pedestrians. The designer was Robert Stephenson, the son of the great railway engineer George Stephenson, who died the year before the bridge opened. The promoter of the bridge was George Hudson — known as the ‘Railway King’ — who ensured that the route of the ‘East Coast Line’ from London to Edinburgh should pass through York and through Newcastle. Hudson got the Newcastle & Berwick Railway incorporated on 31 July 1845 and, as part of the same Act, a great bridge was sanctioned over the River Tyne in Newcastle."
    • p 193 [Still newcastle??] "All but one of these bridges and viaducts was built of brick or stone, but that at Water Street Manchester utilized cast-iron, the avant-garde structural material of the age. Cast-iron had been used in most spectacular and pioneering fashion in the 1770s for the construction of the Iron Bridge in Shropshire — the first iron-made bridge in the world — and more generally from the mid 1790s to form stanchions and beams in mill and warehouse construction. Cast-iron was an attractive option for many reasons: because the ratio between its bulk and its strength was good (a cast-iron stanchion of only very small section was as strong, if not stronger, than a timber stanchion of vast girth); because of the ease and economy with which components could be cast, transported and assembled; and because of its perceived fire-proof qualities. But when it came to construction, cast-iron was an experimental material, its essential qualities untested by use and by time, and so its role in bridge design remained limited in the 1820s."
    • p 194-195: " One man who did not in the 1840s fully appreciate the structural limitations of cast-iron was, it seems, Robert Stephenson. In the mid 1840s he designed a railway bridge across the River Dee in Cheshire for the North Wales coast ... [made extensive use of TEE or I shaped girders ]... These somewhat pioneering methods and materials of construction were chosen by Stephenson because cast-iron was believed to be very strong in proportion to its weight [... and could span longer distances than masonry] ... "
    • p 197-201: FAILURES OF BRITTLE CAST IRON IN UK in 1840s: Examples of cast iron bridges collapsing (brittle, fflex, cracks) .."Despite a growing evidence of a failure in design, Stephenson and the railway company managed to persuade four eminent engineers to speak on their behalf. Men who were usually in ruthless competition to secure commissions now worked together to defend not just an eminent member of their profession but by implication their profession itself and, of course, serve the needs of a railway company that could at some future date prove to be a bountiful employer. For example, Stephenson had been in bitter dispute with Joseph Locke — a long-time rival — but Locke came forward to defend the design of the bridge, despite the fact that he, like I. K. Brunel, distrusted the use of brittle cast-iron in bridge design, preferring timber or masonry."
    • pp 202-220 - Newscastle High Level Bridge


  • P 224- 255 CHAPTER: The biggest and boldest about SUSPENSION BRIDGES
    • p 226-229 "suspension bridges — in which carriageways are supported completed - are ancient in origin [and, with beam and arch types, are one of the three oldest bridge kinds] ..." supported by arches or by horizontal beams of various types (see page 34). The earliest examples of suspension bridges were no doubt inspired directly by nature, suggested by walkways supported, or even created by, suspended vines or vegetation. So the idea would have emerged to create bridges, often of long spans, but by minimal means. No arches, vaults or massive beams necessary, just anchorages from which cables of various types could be fixed, and from which a walkway could be suspended. Ideally cables would also curve from above, perhaps draped over a structure, and descend in an inverted arc to join and add extra support to the walkway. The obvious disadvantage of such simple, almost primitive [structures is that they far from stable, esp in wind, and cannot carry heavy loads] ... "
    • p 229 MODERN SUSPENSION DESIGN/DEFNITION - "Although a seemingly simple concept, the [modern] suspension bridge utilizes some complex and fascinating natural forces. In essence, a suspension bridge is composed of a pair of suspension towers or pylons, set at each end of the river or chasm to be bridged, through or between which traffic or pedestrians pass, and over which are placed the pair of cables. These cables are anchored firmly on the landward side of the suspension towers but hang between them. is partly supported by its footings at the bases of each of the towers and — largely — by the cables from which it is suspended by means of vertical suspenders. ..."
    • p 229 SUSPENSION NG For RAIL "This basic structure has rarely been found entirely adequate, because by its nature, a bridge of this design is very flexible and prone to excessive deformation or movement, either from live loads such as traffic, or from environmental loads such as wind. So the tendency has been, in various ways, to ‘stiffen’ the deck with either girders or trusses. Nevertheless, despite its natural strength and such bolstering, very few bridge designers have dared to utilize the suspension principles for the construction of a railway bridge. The heavy weight and pounding movement of a train is self-evidently in conflict with the [lightweight and flexible nature of suspension bridges] ... "
    • p 232: NIAGRA BRIDGE: ELLET & ROEBLING was a RAIL BRIDGE!! " When in 1848 Charles Ellet Jr. proposed a suspension bridge design to carry road vehicles and trains across the Niagara Falls there was an outcry .... that a suspension bridge was not up to the job. The eminent engineers John A. Roebling and Leffert L. Buck were appointed as consultants and in 1855 a two-tier road and rail bridge was completed, with its longest span measuring 251 metres. But the bridge demanded constant maintenance and renewal of parts and was finally closed in 1897 when the weight of trains had increased beyond the bridge’s loadcarrying capacity. Few cared to repeat the experiment [of rail over suspension bridge] until 1992 when the massive Tsing Ma Bridge in Hong Kong was started. With a central span of 1,377 metres and completed in 1997, it also has two tiers of carriageway — one for vehicles..."
    • DONE pp 232-233 CATENARY vs PARABOLA for SUSPENSION: "..[the shape formed by a hanging cable is very strong, like an inverted arch] ... curved shape is called a called a catenary. If the catenary is copied and inverted it provides an excellent model for an arch to safely bridge the same distance. But contrary to popular belief, the cable of a completed and functioning suspension bridge does not actually form a catenary. It forms a shape equally strong called a parabola. A catenary is formed by a cable curving under its own weight, while a parabola is formed by a cable curving under its own weight and in response to the weight of the carriageway that is suspended from it. "
    • p 232, 249, Self-anchored suspension bridge - DOES NOT require an anchorage for the "land side"; instead the cable is anchored into the deck; p 249 "n 1859 the Austrian Engineer Josef Langer had the idea of ‘self-anchored’ suspension bridges in which the main cables, having passed over the towers, are not anchored to the ground but to the ends of the carriageway. This solution allowed suspension bridges to be built high on piers and remote from land, or located where unstable soil made firm anchorages unlikely."
      • p 249: example is new Bay Bridge (east part) in SF
      • p 343: Most susp bridges are limited to 2 towers; but self=anchoring permits more
    • DONE p 233 SUSPENSION BR AS SYMBOLIC ICONS OF CITIES: "No doubt it is due to this intrinsic beauty and elegance [of suspension bridges] that is at one with the beauty of nature — coupled with the possibility of achieving a heroically large scale — that has allowed suspension bridges to become the much-loved emblems of the city or community in which they stand. For example, the Brooklyn Bridge in New York; the Golden Gate Bridge in San Francisco; the Clifton Suspension Bridge in Bristol; and the Széchenyi"
    • p 236: EARLY SURVIVIGN SUSPENSION BRIDGE IN EUROPE: "One of the earliest surviving suspension bridges in Europe — certainly in Britain — is the Union Bridge near Berwickupon-Tweed. It was designed by Captain Samuel Brown of the Royal Navy, and has an impressive span of 137 metres which made it the longest wrought-iron built suspension bridge in the world when it was built in 1820. Originally the carriageway was suspended by three chains on each side, with each chain formed by linked bars of wrought-iron. Brown, no doubt fully aware of the flexible strength of the tall masts of sailing ships and the potential of a wrought-iron chain, designed his bridge to move with the wind, rather than to resist it, and gave his slender and lightweight bridge a capacity for movement that remains disconcerting."
    • P 236-238: AUTHORS FAVORITE DECORATIVE SUSP BRIDGE : "Yet one more suspension bridge was completed in 1826 that, I admit, is in many ways my favourite. The Bank Bridge in St Petersburg, Russia demonstrates the decorative potential — and rational elegance — of the type that so appealed to the sensibilities of the age. It was designed by Wilhelm von ..."
    • p 240-243? - CLIFTON SUSPENSION BRIDGE IN BRISTOL
    • p 243: MARCHING IN LOCK-STEP LEADS TO BRIDGE COLLAPSE: "Chaley built another suspension bridge (which survives) at Corbiéres, France, in 1837, with a span of 121 metres, and then took on a major suspension bridge project at Angers, France. Known as the Basse-Chaine Bridge and completed in 1839 with a central span of 102 metres, the bridge became infamous in April 1850 — indeed almost brought the building of suspension bridges to a close in continental Europe — when it suffered a sudden and catastrophic collapse that resulted in the death of 226 people. The circumstances of the collapse are most curious and at the time revealed much about the still not fully understood structural nature of suspension bridges. Marching smartly in step, 478 soldiers began crossing the bridge, when suddenly, the ‘dynamic load’ represented by the rhythmical pounding of the column of troops caused something awful — and utterly unexpected — to happen. The bridge began to vibrate and twist in a corkscrew-like manner. In the process, a suspension cable was dislodged from its concrete anchorage and the astonished soldiers tipped into the river below. A subsequent inquiry determined that not..."
    • P 252-253: TACOMA NARROWS COLLAPSE: RIGIDITY REQUIRED ...
  • p 256-273 - CHAPTER: STRUCTURAL PERFECTION - Entire chapter is about GUSTAVE EIFFEL and the GARABIT VIADUCT - 1977 descendent is new river gorge bridge
    • p 268: "JUST ONE GLANCE AT THE GARABIT RAILWAY Viaduct in Auvergne, southern France, is enough to make it clear that you are in the presence of what is — in many ways — the perfect bridge. It is breathtaking in its ambition, minimal in the way that ambition is realized, seemingly ruthlessly functional in its design with no concession paid to superficial ornament, and, of course — it is utterly, ravishingly, sublimely beautiful. The huge, yet delicately fabricated and almost transparent, crescent-shaped arch, on the crown of which is poised a horizontal sliver of track, is incredibly visibly satisfying. The viaduct appears as pure engineering, its perforated and skeletal form being, simultaneously, a diagram of precisely calculated strength and — almost paradoxically — a thing that is, almost impossibly immaterial and light. According to the renowned biographer of great bridges, David P. Billington, the viaduct epitomizes the points of excellence that define the world’s best bridges. Its design is unusually ‘efficient’ because it achieves great strength with little material, is exceptionally ‘handsome’, being light in appearance and with a ‘more integrated overall form’ and more ‘visual sophistication’ than the vast majority of bridges, and it was unusually ‘economic’ in cost and construction time.% And then there’s the setting. The rolling and mountainous terrain of the Central Massif has always been a challenge to"


  • p 274-309 - CHAPTER: Defining Places (icons & Symbols)
    • SYMBOLIC and ICONIC BRIDGES assoc with citeis esp NEW YORK
    • p 276 "THE BRIDGES OF NEW YORK ARE AMONG THE GREAT engineering wonders of the world. They, collectively and almost in themselves, encapsulate the history of bridge design and construction during the last 150 years. They are characterized by massiveness of scale, boldness of vision and an almost bloody-minded ruthlessness when it came to realization. Often they are raw, even brutish in the manner in which they thrust themselves from the fabric of Manhattan Island and across the Hudson and East Rivers. Some are supreme examples of their kind, such as the Brooklyn Bridge, ..."
    • p 279-282? Queensboro bridge 1910 Cantilever
    • p 281-284? Manhattan bridge 1930s Suspension
    • p 283 - 291 Brooklyn bridge 1880s Suspension
    • p 292 - 294 CANTILEVER BRIDGES IN GENERAL, DESIGN, DEFINTION
    • P 292: "Suspension bridges can be the most daring and visually thrilling of bridge designs — lofty, minimal, supremely elegant, and with breathtakingly wide spans. But, to my mind, cantilevered bridges are the most exciting, the most satisfying to contemplate. At their best and biggest they are the great beast of bridges, often raw, almost brutal in design and construction, and which in their engineering both utilise and in spectacular manner defy the laws of nature. The cantilever bridge is a variant on the three basic types of bridge, each based on a natural prototype: the beam bridge that is in essence like a log across a stream; the arched bridge that is like a natural rock formation; and the suspension bridge that is inspired by hanging vines and creepers. The cantilever is, in a sense, a more complex and engineered version of the beam bridge. Although originating in ancient Asia [cantilever bridges only became wisely used in the west in mid 19th century]
    • p 293: "In a typical, large, late-nineteenth-century cantilever bridge, tall towers support horizontal cantilevered carriageways. Together these towers and carriageways — wrought typically out of a lattice-work of mutually supporting and bracing metal components — form a structurally integrated truss in which each carriageway, thrusting in opposite directions, is counterbalanced, one against the other. This is the simple, basic and elegant principle of cantilevered bridges: to use weight to balance weight; to create a state of poise or equilibrium by perfectly pitting one load or thrust against another. Cantilevered carriageways are linked by suspended spans and the weights of these spans counterbalance each other until the bridge heads at either end are reached. Then the loads are balanced by approach works and structural equilibrium achieved."
    • p 293 FORTH BRIDGE USED STEEL, ONE OF THE FIRST "An early and outstanding example of this type of construction is the Forth Railway Bridge in Scotland. Designed and built between 1887 and 1890 its engineers — Sir Benjamin Baker and Sir John Fowler — were inspired by the structural possibilities offered by steel (just then made legal in Britain as a primary building material) and by the cantilever principles found in the skeletons of large mammals. D’Arcy Thompson, in his book of 1908 entitled On Growth and Form, argued that the pioneering structural solutions of the age were generally inspired by nature and analogous with anatomical designs. He observed similarities in the structures of bones and made-made girders and columns, and pointed out that the design of the Forth Railway Bridge exemplified the pure, functional beauty that comes from the application of rational, mechanical — and natural — design principles. He pointed out that the steel tubes used in the bridge correspond to the structure of strong cylindrical plant stalks (in fact the bridge’s tubes even have strengthening rings added to their joints as..."
    • p 292-298 Forth bridge Cantilever 1885-1895 - RAIL (vs NYC road)
      • NOTES that the three big NYC bridges were for persons, carriages, and trams thus SUSPENSION was okay; but FORTH was Rail, so was Canitiliver
    • p 298 ASIA CANTILEVER BRIDGES "Smaller and traditional cantilevered bridges, of the type found in large numbers in China, Tibet, Bhutan and Japan, possess two ‘anchor arms’ that extend towards each other from opposite sides of the river or gorge to be bridged, and are linked by middle spans. Typically the anchor arms of these bridges reduce the width of the chasm to be bridged by cantilevering stone slabs out from the bridgehead. These projecting stones support timber beams that project yet further and in turn are cantilevered. Additional beams can be added, each lighter than those below and projecting yet further, with the uppermost and furthest projecting timbers finally being linked by a horizontal span. A good, and larger than usual, example of the traditional Asian cantilever is the remarkable Shogun’s Bridge at Daiya-gawa, Nikko, Japan that spans 26 metres and is the oldest known cantilever bridge dating back to the ninth century AD (some sources even claim the fourth century) but rebuilt in 1638 and again in 1902. It is a curious design incorporating a pair of hewn stone piers and lintels, strengthened by stone ties, which support cantilevered beams linked by a central suspended timber span, with all timbers shaped to form an elegant segmental arch."
    • p 303-310 Queensboro bridge 1910 - very large cantilever (and TRUSS in middle) in NYC
    • p 306: 88 deaths on Queensboro brudge construction "Railway Bridge, and construction was started on a revised design. But in 1916 its central section collapsed while being raised and a further thirteen workers were killed. The bridge, when finally completed, did indeed set world records both in number of dead workmen (eighty-eight in all) and in the length of its cantilevered span, but it didn’t have an epochmaking look. Indeed it appeared to be a somewhat ungainly version of the Forth Railway Bridge. So although the Quebec Bridge robbed the Queensboro Bridge of its record for length of cantilever it didn’t even begin to challenge it in the beauty stakes or emulate its peculiar visual magic."
    • P 307-308 Howrah Bridge in india Cantilever
  • P 310-339 CHAPTER: WORKS OF ART - ?? MOSTLY CONCRETE BRIDGES
    • p 312 "TWENTIETH-CENTURY ENGINEERS COULD CREATE works of contemporary abstract art — minimal and beautiful — that, like the works of Pablo Picasso, evoked the pioneering and inventive spirit of the age. Bridges could also show the artistic potential of new materials that permitted the realization of unprecedented structural forms. The bridges of the early twentieth century could look like bridges had never looked before, and do things that bridges had never dared do before, because they were made in new ways from new materials.
    • p 312 "All this is revealed by the first sight of the Salginatobel Bridge, near Schiers, in Switzerland. It leaps across a precipitous Alpine gorge, its minimal and shallow parabolic arch — constructed with three hinges to permit inevitable movement — spans 90 metres to allow a narrow road to wind on its way along the mountainside. It is quite simply beautiful: its simple form emotive and expressive of strength and daring. It is abstract sculpture of the highest quality — not least because of its plastic quality and apparently seamless construction. Instead of metal parts riveted, bolted or welded together, it is made of concrete, cast in moulds and reinforced with steel rods to create a single monolithic form. It is not ornamented in any way, nor its surface coloured or painted,"
    • p 314 REINFORCED CONCRETE "Although reinforced concrete was a new structural material in the early twentieth century, concrete itself has an ancient and noble history as a building material. It seems to have been used first, in any significant quantity and manner, in the second century BC by Roman engineers. They perceived that it possessed a number of very useful qualities and as a sort of liquid stone capable of being cast to create huge monolithic forms, it made construction both quick and cheap, and when used skilfully allowed the realization of unprecedented building forms — for example the vast cast concrete dome of 43.3 metre diameter over the Pantheon in Rome."
    • p 317 PORTLAND CEMENT - NEW VS ROMAN ".... . The success of [19th cent UK imiitation] "Roman cement" led others to experiment with novel mortar mixes, and in 1824 Joseph Aspdin invented what he termed ‘Portland cement’. .... It was an invention rather than a discovery because it was the product of selecting and mixing various materials together to create a very strong, quick-setting cement. So essentially, if somewhat paradoxically, it was an artificial natural cement. This early Portland cement bears little relation to modern ‘ordinary Portland cement’ which, in its essential mix, dates from the early 1840s and was developed by Aspdin’s son William. This improved version of Portland cement contained a material named aire (tricalcium silicate, a key crystalline mineral active in Portland cement) that allowed..."
    • P 320: REINFORCED CONCRETE "Along with steel, concrete was, in its new manifestation, to become from the early twentieth century the materialof-choice for most medium to large-scale buildings in most parts of the world. The new idea was to give concrete significant tensile strength by reinforcing it with metal bars. Since the early nineteenth century, various innovative designers had played with the idea: for example, Marc Brunel — the father of the great bridge builder Isambard Kingdom Brunel — tested the concept in 1832. During the construction of his Thames Tunnel — the first in the world to be built in a city beneath a large body of water — he had experimented with the construction of an arch with bricks laid in Roman cement and reinforced with hoop iron. Brunel managed to get his arch to achieve a cantilever of 18.3 metres (60 feet).” This was an impressive achievement, and suggested that for much arch construction of the future expensive timber centering could be dispensed with. This experiment did not launch a consistent programme of research into means of reinforcing concrete made with Roman cement. But developments did take place during the first half of the nineteenth century, if only slowly and in a haphazard way...."
    • P 321 "of course, the great enemy of many metals, especially iron, causing it to rust and, in the process of corrosion, to expand. Such expansion would unleash a vicious cycle leading to an increase in the number and size of cracks and so to accelerate corrosion and shatter the concrete cover. Although this problem was anticipated it was, for many early metal reinforced concrete structures, to prove near, or actually, fatal in practice ... During the 1870s and 1880s developments were pushed forward through a series of patented systems, perhaps the most notable early example being those taken out by a Parisian gardener named Joseph Monier for farm equipment and flowerpots made of concrete reinforced with round iron bars.7? Monier was not only a maker of flowerpots, however. He was also a designer of bridges, and in 1875 — at Chateau de Chazelet, Indre, France — he constructed a charming pedestrian bridge of simple girder type with a span of 13.8 metres. The structure may be modest but it was epochmaking — the world’s first bridge to be made out of metalreinforced concrete."
    • pp 322: EARLY REINFORCED CONCRETE BRIDGE: "Erected between 1899 and 1900, the Camille-de-Hogues Bridge at Chatellerault, Vienne, France, is logical, generally devoid of superfluous historicist ornament and is — in pioneering Modernist manner ~ a fairly honest and direct expression of its materials and methods of construction. The bridge crosses the river in three wide and shallow segmental arches (the widest with a span of 52 metres) that carry a road supported both by the crowns of the arches and by thin, reinforced-concrete piers that occupy their spandrels. All in all, the bridge possesses an elegant lightness of form that would have been virtually, if not absolutely, impossible to achieve in masonry and very difficult to match in metal. Even more astonishing as a pioneer of reinforced concrete "
    • p 326: PRESTESSED CONCRETE "enhanced strength was to permit the construction of beams, floor-plates and bridges with longer spans than was possible with conventional reinforced concrete. The means of achieving this, Freyssinet and his fellow pioneers concluded, was not to attempt to upgrade the concrete mix or increase the size or number of steel reinforcing rods, but to revolutionise the means by which reinforced concrete was manufactured. Structures made with prestressed concrete were usually not formed with concrete cast in situ — that is, poured on site as was usual with conventional reinforced concrete — but were mostly made from components cast under specially controlled conditions in a factory. These precast components, for example beams or panels, were then to be delivered to the construction site. So, unlike conventional reinforced concrete that resulted in monolithic structures, prestressed concrete heralded the arrival of prefabricated concrete construction with components assembled and fixed together on site."
    • p 326 PRE_TENSIONED : "These prestressed concrete components have a very novel character. Steel rods or tendons are pre-tensioned in factory conditions and then concrete is poured over them. Common ways to do this are to heat and thus expand the steel rods, clamp them, and then cover them with concrete; or to tension the steels by jacking them between two end anchorages before covering them with concrete. When the concrete has hardened the tension on the rods is released and transfers to the concrete — with which the rods are integral — giving the component additional tensile strength. To make things a little more complicated to understand, prestressed concrete components can also possess a structural character that inverts nature, in a sense reverses the Stonehenge lintel effect. Compressive force can be at the bottom of the lintel not the top, and tensile force at the top not the bottom, so in a sense, a lintel’s structural strength is springing upwards, cleverly limiting the possibility of deflection and countering the forces — gravity and load — that naturally press down upon it."
    • P 326-327 POST-TENSIONED "A post-tensioned form of prestressed concrete was also evolved, which permitted it to be cast in site. In this system the steel rods are tensioned after the concrete has hardened, usually by leaving their ends projecting from the concrete and threaded so that tensioning turnbuckles can be applied. The rods then transfer their tensile strength to the surrounding concrete.
    • pp 330-335 - Robert Maillart and his bridges made of reinforced concrete
  • p 340-355 CHAPTER: MODERN MEGA BRIDGES - Especially Cable-stayed
    • p 342-344 "DRIVING ACROSS THE 2,460-METRE-LONG MILLAU Viaduct — for drive you must — is one of the great bridge experiences of the world. When mist lies heavy in the valley of the Tarn in southern France, over which the viaduct passes, you find yourself flanked by tall masts — one at 344 metres is loftier than the Eiffel Tower — and motoring, 270 metres high, amongst the clouds, seemingly into infinity. Bridges can make you feel like a god...."
    • p 343 "The Millau Viaduct, opened in 2004 and designed by Michel Virlogeux with Norman Foster, is a fascinating variation of the traditional suspension bridge. It is a cablestayed structure in which the deck is attached directly to the towers by a series of diagonal cables, rather than to an arching cable descending from the towers and anchored in the ground."
    • p 343 CABLE STAYED PROS & CONS "This system has strengths and weaknesses. In cable-stayed bridges the towers or pylons are the primary load-bearing structural component: they operate under compression as a fixing point for all the cables supporting the deck so there is no need — as in suspension bridges — to construct firm cable anchorage on land. The freedom from this obligation can be a great benefit, because the construction of firm anchorages can be difficult if the soil conditions are unfavourable and anchorages have been known to fail — as at the Basse-Chaine Bridge in France in 1850 (see page 243). In addition, cablestayed bridges possess greater structural rigidity than suspension bridges so that deformation of the carriageway under the load of traffic or the environment is reduced. Also cable-stayed bridges can be built by cantilevering out from the towers, with cables acting as temporary then permanent support to the carriageway, and so are generally economic of time and money to construct. Another advantage is that the cable-stayed bridge can possess only one tower or — as displayed by the Millau Viaduct — the system can be easily extended by the addition of extra towers as required."
  • p 343-346: CONTRAST CABLE-STAYED vs SUSPENSION:
      • p 343 Cable stay permit mutilate spans adjacent; unlike Suspension bridges which are typically limited to 2 towers (except for Self-anchored suspension bridge)
      • p 346: SPan max of Cable-stayed are much shorter than Suspension (but longer than Cantilever)
      • p 346-347 Cable-Stayed typically require bulkier, stroner, heavier decks than suspension
      • p 347: Cable-stay types: FAN vs HARP.. Fan example: Octávio Frias de Oliveira Bridge (Brazil); HARP type: Millau viaduct.
    • p 348: Span length cannot be indefinitely long: "In bridge design size is, very much, an issue. As Galileo pointed out in the early seventeenth century, when discussing the length and bulk of beam bridges, scale can only increase to a limited extent before a structure breaks under its own weight (see page 32). But the repetitive potential of cablestayed bridges, used in conjunction with suspension or cantilever structures, viaducts and pioneering new technology has led to the construction in recent decades of bridges with extraordinary lengths, indeed bridges bigger in every sense"
      • p 348-349: HEnce the use of viaducts or causeways that chain-together multiple spans. "For example the Hangzhou Bay Bridge China, completed in 2007, has a length of 35.5 kilometres [incl about 500 beam spans] and incorporates a 448 metre-long cable-stayed span. It is the longest transoceanic bridge in the world — stripping the title from the 32.5 kilometre long sea-spanning Donghai Bridge at Shanghai, completed in 2005 and also with a cable-stayed section — but is nearly 3 kilometres shorter than the 38.4 kilometre long Lake Pontchartrain Causeway, dating from the 1950s, in Louisiana, United States. The 8.2 kilometre long Sutong Bridge across the Yangtze River in China — completed in 2008 — has, at 1,088 metres, the longest cable-stayed span in the world, followed by the 1,018 metre span of the cablestayed Stonecutters Bridge of 2009 in Hong Kong. Both these will be overtaken by the 1,104-metre main span of the cablestayed Russky Island Bridge, Vladivostok, Russia, which is due for completion in 2012."
        • Google says: THe Hangzhou Bay Bridge has approx 500 beam-style concrete spans (plus 2 cable stay spans)
    • p 349: BLurry dividing line between bridge vs causeway vs viaduct : "When bridges get to this massive size, and incorporate different structural systems, confusion sets in over definitions. Are they true bridges, or causeways linked by bridges or simply viaducts or raised carriageways of great length? For example, what exactly is the 54 kilometre long Bang Na Expressway in Thailand that, completed in 2000 [A raised road that traverses several city blocks] is of box-girder construction consisting of sections of 42 metre span, but which crosses no significant stretch of water? And is the 79.7 kilometre long Weinan Weihe Grand Railway Bridge, Xi’an, China, completed in 2008, essentially a raised railway track? A consensus has yet to be reached by those authorities that define, measure and compare the vital statistics of the world’s bridges. Seemingly more certain of their identity as bridges are the Manchac Swamp Bridge, in Louisiana, USA, that was completed in 1979 and straddles its way across over 36 kilometres of swamp with its concrete trestles resting on piles sunk nearly 78 metres into the water-logged land; the..."
    • p 353 Vasco da Gama Bridge in Portugal - CAble-stayed example
    • p 353 Øresund Bridge connecting sweden & Denmark- CAble-stayed example

David Brown 2005 Source " Bridges: Three Thousand Years of Defying Nature"

[edit]
EXCELLENT HISTORY BOOK
  • p 18 ANCIENT "For tens of thousands of years before the emergence of the first great civilizations, primitive bridges were simply used for aiding the movement of hunter-gatherer tribes. Some 10,000 years ago, however, the rise of agriculture led to the first great change in society. Farming begat settled communities — villages, and then small city-states. Settlements needed buildings, farms required irrigation, and as populations expanded over the centuries, these needs engendered the development of engineering skills. Despite the achievements of the Egyptians and the Greeks in monumental architecture, the Roman civilization was the first to develop a real expertise in the design and construction of bridges. Even so, there are fragments of archaeological evidence, contemporary accounts, and even rare standing structures that have survived from much earlier times."
  • p 18: ANCIENT "Sennacherib early in the 7th century BC. To carry the waters of one canal to the city, he built a stone aqueduct, 280m (920ft) long and 20m (66ft) wide, across a small river-valley at Jerwan, 40km (25 miles) away. From the point of view of bridge construction, the interesting part was the 27m (90ft) section across the river itself, which was supported on five corbelled arches ... In 626BC the Chaldean leader Nabopolassar made Babylon his capital; and under his rule, and that of his son, Nebuchadrezzar I, it became the greatest metropolis the world had yet seen. A bridge across the Euphrates, built close to the stepped tower now. Estimates of its length vary from 120m to 200m (390-650ft); and excavations revealed the remains of seven piers in baked brick, stone, and timber, each roughly 9m by 20m (30ft by 65ft). The Greek historian Herodotus (c.490-425BC) ascribed the construction of what may be the same bridge to a Queen Nitocris, who he said diverted the river into an artificial basin and built the bridge in the..."
  • p 20: ANCIENT "The first bridge in Rome of which we know the name was the Pons Sublicius, said to have been the one defended against the Etruscans in the 6th century BC by the legendary hero Horatius Cocles. Sublica means “pile” or “stake,” but it is probable that, as on most Roman bridges, timber was used for the entire structure and not just the foundations. The popular conception of the Roman bridge as a series of monumental stone arches derives simply from the fact that so many stone bridges have survived, whereas every single timber bridge has perished. One does survive in reports, however: in his De Bello Gallico, Julius Caesar gives a remarkably detailed account of a timber trestle bridge, perhaps 400m (% mile) long, which he ordered to be built across the River Rhine near present day Coblenz in 55BC."
  • p 23: ANCIENT "The aqueducts that carried water into the cities of the Roman Empire were often extraordinarily extensive. Rome itself was served by a network of 11, which, on completion of the last, in AD226, totalled 560km (348 miles) in length. Only one-seventh of that distance was above ground, but of that, as much as 60km (37 miles) had to be carried on arches to keep it high enough to maintain flow. Elsewhere, the systems were smaller than in the capital, but on occasion they required structures of extraordinary height and length in order to carry the water across valleys. Indeed, the Romans’ greatest single aqueduct, built in the reign of Hadrian to serve Carthage in North Africa, extended no less than 141km (87% miles)."
  • p 25: ANCIENT "Perhaps the greatest of all Roman stone bridges is in complete contrast to the Classical, travertine limestone-faced sophistication of these bridges. Lofty, remote, strategic, and awe-inspiring, the Puente de Alcantara in Spain crosses a steep, narrow valley of the Tagus River, close to the border with Portugal. Everything about it speaks in superlatives, from the towering granite piers up through the six great arches — the central two of which are the longest to have survived from Roman times — to the parapeted roadway more than 50m (164ft) above the river bed, higher even than the Pont du Gard. As on that other masterpiece, the granite voussoirs were laid without mortar, but have nonetheless survived the floods of nearly 2,000 years."
  • P 26: ANCIENT CHINA "From prehistoric times, the Chinese independently developed many types of bridge to deal with the immense range of the country’s topography: stepping stone (“turtle”) bridges, beam bridges in timber and stone, trestle bridges, bamboo and ironchain suspension bridges, and arches in timber and stone. With the expansion of the Roman Empire, the semicircular masonry arch form spread eastward. It may have influenced Chinese designs, but with one bridge, completed less than 150 years after the fall of the Roman Empire in the West, Chinese engineers executed a structural leap forward unparalleled in the West for seven centuries.... It is difficult to exaggerate the technical mastery and historical importance of the Zhaozhou (Anji) Bridge at Zhao Xian in Hebei Province, completed early in the 7th century AD, and designated in 1989 as an International Historic Civil Engineering Landmark ..."
  • p 26: ANCIENT "Elsewhere in China, hugely different bridge designs had been executed. For example, the principle of cantilevering was taken to one logical conclusion in the 10th century on the Poh Lam Bridge over the Dragon river in Fukien. The structure of this bridge consists of colossal corbelled granite beams weighing perhaps as much as 200 tonnes each and providing spans of up to 20m (65/ft). Other megalithic Chinese bridges of this period were as long as 2km (1% miles), like the Anping Bridge whose 331 boat-shaped piers, supporting innumerable parallel stone slabs, march across an inlet of the sea 30km (18% miles) south-west of Quanzhou."
  • p 28 MEDIEVAL INTRO "The collapse of the Roman Empire in the West brought to an end a long era of engineering achievement, including the construction of bridges with any pretensions to permanence. It was only with the building of the Pont d’Avignon, which began in 1179, that Western medieval engineers for the first time produced a bridge that matched the masterpieces of the Romans."
  • p 30:MEDIEVAL FRANCE "The extensive ecclesiastical building programme that accompanied French religious fervour at the end of the 12th century seems to have included bridges as well as cathedrals and monasteries. The provision of a bridge was regarded as an act of pious charity, and specially dedicated religious orders were established to build and maintain masonry bridges and hospices at dangerous crossings. According to Viollet-le-Duc, the 19th-century architectural historian, the first of these bridges was built over the River Durance, at a place originally known as Maupas but subsequently renamed Bonpas, by a monk called Bénoit in 1164. In the years that followed, several other bridges were erected under Brother Bénoit’s direction by the group of monks who later became known as “Les Fréres du Pont’; and Viollet-le-Duc also credits him with the famous bridge over the River Rhéne not far from Bonpas, at Avignon. But local legend, and indeed the Catholic Church, ascribe the bridge to a shepherd called Bénézet, who had a vision in 1178, in which he was commanded by God to build it. When the Bishop"
  • p 32: MEDIEVAL ITALY "Medieval Florence was a flourishing commercial capital. The links that led to southern cities across its flood-prone River Arno were as essential to its continued prosperity as was the success of its bankers and weavers. Timber bridges had been built both by the Romans and during early medieval times. A Ponte Vecchio was already in existence in 1077, when the Florentines decided to bring the course"
  • P 36 RENAISSANCE - "Paris joined the metropolitan stone bridge-builders at the beginning of the 16th century, with the construction in only seven years (1500-07) of the six-arched, 124m (407ft) Pont Notre-Dame between the right bank of the Seine and the Ile de la Cité. This replaced.a timber bridge that had collapsed in 1499 and, like it, carried a double row of houses on its 23m (75/ft) width. ... The most imposing French bridge of the Renaissance was another “Pont Neuf,” this time in Toulouse, which was completed in 1632 after almost a century of building. It boasted an exceptionally long 31.7m (104ft) main span, with an arch that remarkable evolution of the curve in a Renaissance bridge was to be found in the heartland of the movement, in Florence, on the Ponte Santa Trinita, completed in 1569. Disdainful of the traditional Roman semicircle and the “barbarous” Gothic point, the architect, Bartolommeo Ammanati Battiferri da Settignano (1511-92), designed three near-elliptical arches with rises of only 1:7, but provided them with extremely shallow angles at their crowns to reduce the danger of collapse, and artfully concealed them behind decorative pendants. Despite its breathtaking beauty, the shape that resulted has since become known simply as “basket handled. remarkable evolution of the curve in a Renaissance bridge was to be found in the heartland of the movement, in Florence, on the Ponte Santa Trinita, completed in 1569. Disdainful of the traditional Roman semicircle and the “barbarous” Gothic point, the architect, Bartolommeo Ammanati Battiferri da Settignano (1511-92), designed three near-elliptical arches with rises of only 1:7, but provided them with extremely shallow angles at their crowns to reduce the danger of collapse, and artfully concealed them behind decorative pendants. Despite its breathtaking beauty, the shape that resulted has since become known simply as “basket handled.”
  • p 37 RENAISSANCE "... Verantius considered the possibilities of structures where the forces of tension and compression were self-contained. Traditionally, masonry-arch bridges were massively buttressed to resist the downward and outward thrust of their self-weight, but Verantius illustrated a bridge in which the outward thrust of the masonry arch was restrained by iron tie-rods, themselves braced by further rods suspended from the arch. He then abandoned masonry completely, illustrating another bridge in which arch and deck were entirely cast in bronze."
  • P 40 RENAISSANCE ERA OUTSIDE EUROPE - "While European engineers were refining old bridge forms and beginning to contemplate new ones, fascinating divergences and convergences were taking place on other continents. For example, some Chinese iron suspension bridges were using eyebar chains that were virtually identical to those in Verantius’ unbuilt design (see p.37). Other, quite different types of bridge became important ingredients in the aesthetic, philosophical, and spiritual unity that constituted the Chinese garden. Sometimes only simple arrays of stepping stones were used, but a more elaborate structure, and one peculiar to China, was the timber zig-zag, in which the everchanging direction of the timber trestles symbolized the unity of opposites — the concept of yin and yang. Another constant feature of Chinese bridge design was the use of tall, slender arches, as on the famous Jade Belt stone bridge in the Summer Palace at Beijing, which also contains the Seventeen-arch Bridge, in which eight pairs. As early as the 7th century, the Chinese influence on garden and bridge design spread to Japan, where the tradition of allowing the walkway to follow the curve of the arch became equally well established. One particularly celebrated example is the five-arched Kintai-Kyo Bridge over the Nishiki River in Southern Honshu. The timber bridge was built in 1673, and subsequently one arch of the bridge was rebuilt every five years. "
  • p 45 RENAISSANCE - LONDON " For more than 500 years, Old London Bridge was the capital’s only crossing point over the River Thames, its narrow deck cluttered with houses, as much a hindrance to movement between the north and south sides of the City as the multiplicity of narrow, sluice-like channels between its many arches were to river traffic. Nevertheless, its uniqueness created such a flourishing concentration of trade that, at least among those who benefited, there was strong opposition to the construction of another bridge. The petitioners who set out in 1734 to campaign for the construction of a new bridge at Westminster had their work cut out to persuade Parliament to approve."
  • p 44 RENAISSANCE - FRANCE "Under the influence of King Louis XIV, a nationwide road system became a priority in France, leading to the establishment in 1716 of the first professional engineering body, the Corps des Ponts et Chaussées; and in 1747 the need to educate the engineers led to the foundation of the world’s first school of engineering, the Ecole des Ponts et Chaussées, under the direction of the able and experienced bridge-builder, Jean-Rodolphe Perronet (1708-94)."
  • p 46 INDUSTRIAL REVOLUTION - ELLIPTICAL ARCH "Although Charles Labelye’s methods of founding the piers of Westminster Bridge incorporated new technology, the shapes of his arches were Roman. When, therefore, in 1759, Robert Mylne (1734-1811) presented a design with elliptical arches for the next bridge in London (at Blackfriars) to be approved, conservative heads shook; and their doubts were reinforced, with more eloquence than engineering knowledge, by no less a man than Dr Johnson. As built, Mylne’s nine arches for Blackfriars Bridge still had modest ellipses, and for the foundations he used an improved version of Labelye’s floating caisson, but in general his masonry-arch designs seem tame beside the brilliance and daring of Perronet"
  • p 46 INDUSTRIAL REVOLUTION - CAST IRON 1 "Although cast iron is stronger in tension than masonry, and also most timber, its real advantage is its greatly superior compressive strength. This is reflected in the slender ribs and connectors of the Ironbridge — which is structurally an arch in compression. Indeed, its builders did not yet really comprehend the potential of the material: it contains a large amount of redundant cast iron, and the jointing echoes timber practices in its dovetails and mortises. The Ironbridge is, in fact, significant almost in spite of itself. Within a few years, iron bridges were to be designed and built that were truly representative of the Industrial Revolution, developing bridge technology per se and exploiting the possibilities"
  • p 47 INDUSTRIAL REVOLUTION - CAST IRON 2 "The next big step forward in the use of iron for bridges stemmed from a man now remembered as a (political) revolutionary, Thomas Paine. After taking part in the USA's fight for independence, Paine proposed the construction of long iron spans, to avoid the necessity of founding arch piers in ice-clogged rivers. In 1787 he went to London to raise support for his proposals..."
  • p 50 INDUSTRIAL REVOLUTION - CAST IRON 3 "In the early 1790s, a rich landowner called Rowland Burdon took over a project to build a bridge across the Wear at Sunderland, which in his opinion required a single, very long span. With his friend and advisor, the architect Sir John Soane, Burdon had become familiar with the covered timber truss bridges erected by the Swiss Grubenmann brothers, which were the climax of a wave of interest in timber-truss bridges in the first half of the 18th century generated predominantly by Palladio’s designs. These bridges proved the practicality of spans much longer than those that were then thought feasible in masonry, and the examples of the bridge at Coalbrookdale and Paine’s prototype on Paddington Green demonstrated a new way forward with iron. Burdon engaged a local builder, Thomas Wilson, under whose supervision six huge ribs were fabricated and were erected over the Wear in only ten days in 1796."
  • p 53 INDUSTRIAL REVOLUTION - CANAL BRDIGE (WALES) - "A canal-builder, faced with the need to carry a waterway across a valley, has two choices: a series of descending and ascending locks, or an aqueduct. In 1759 the Duke of Bridgewater decided on the latter for Britain’s first wholly artificial canal across the Irwell Valley in Lancashire. The resulting Barton Aqueduct, designed by James Brindley, became a model for many similar structures, as Britain’s canal network grew during the remainder of the century. The Bridgewater Canal was carried over the river itself on three low segmental arches in a trough made of waterproof puddle clay —"
  • DONE p 58 INDUSTRIAL REVOLUTION - RIGID SUSPENSION BRIDGES "It was an American, James Finley, who first identified the major components of the modern suspension bridge: a system comprising main cables and vertical suspenders from which was hung, most crucially, a level deck braced by trusses. A judge and a justice of the peace in Fayette County, Pennsylvania, Finley built his first bridge, a 21m (69ft) span across Jacob’s Creek, in c.1800. In 1808 he patented a suspension system, and in 1810 he published a “description of the Patent Chain Bridge” in a New York journal, The Port Folio .... The most substantial Finley-type bridge was the single 74m (243ft) span Merrimac Bridge, built under licence by John Templeman in 1810. Ten chains, suspended between the 11.3m (37ft) high stone abutments, supported two 4m (13ft) roadways on hangers. As the Newbury Port Herald of 14 December, 1810, affirmed, “Horses with carriages may pass upon a full trot with very little perceptible motion of the Bridge.” The Merrimac Bridge collapsed under snow in 1827, but it was rebuilt and survived until 1913, when it was replaced with unwonted zeal by a near-replica in concrete and steel and the last original design of “The Father of the
  • P 60: SUSP WALES - The Menai Strait Bridge; p 62: SUSP SWITZERLAND: The Grand Pont Suspendu
  • p 64-82: Chaper 5: RAIL BRIDGES & BRUNEL
    • P 64: Brunel etc "More than any others, three men drove the vast programme: George Stephenson's only son, Robert (1803-59), Isambard Kingdom Brunel (1806-59), and Joseph Locke (1805-60). Locke is the least-known and, from the bridge-building point of view, the least interesting, but he was responsible for an immense body of economically planned and efficiently administered work. Beginning as an assistant to George Stephenson, he went on to supervise the construction of the eastern section of the Liverpool to Manchester Railway, before being given overall responsibility for his first complete line, the 1837 Grand Junction Railway from Warrington to Birmingham. The one large viaduct on this route stretched across the Vale Royal near Northwich, and its pattern of 20 regular arched spans became a prototype for hundreds of similar structures."
    • p 65 TRAINS; BOWSTRING ARCH (SUSP NG): "A moving train imparts a far more severe single live load to a bridge than any combination of road vehicles or pedestrians. But the stress on the structure of any substantial masonry-arch bridge imposed by its own dead load is comparable with, or exceeds, the stress generated by any practicable live load. As a result, the first railway bridges were all masonry arches. Stone beams would of ... of the bowstring arch is Robert Stephenson's High Level Bridge in Newcastle upon Tyne, whilst the versatility demonstrated by Brunel himself in the design of the timber viaducts in Devon and Cornwall for his Great Western Railway was without peer (see pp.68-9)"
    • P 68: TIMBER VAIDUCTS in UK (BRUNEL); p 70: CLifton Suspension bridge Bristol UK; p 74: Royal Albert Bridge UK Saltash;
    • P 76: FAILURE - Tay Bridge Disaster Scotland
    • P 78: FORTH RAIL BRIDGE SCOTLAND;
    • P 80: MOVING BRIDTGES: TOWER BRIDGE LONDON
  • p 82 -92: Chapter 6 New bridge ideas in US
    • p 82 WOOD MATERIAL "In a rapidly growing country, as yet untouched by the Industrial Revolution, the need for speed of construction and the abundance of the material combined to make an irrefutable case for wooden bridges. Perhaps the first really ambitious example was designed and built by Colonel Enoch Hale in 1785, to carry a turnpike forming part of the main trading route from Boston to Montreal across the Connecticut River at Bellows Falls in Vermont. The sketchy surviving documentation indicates a continuous deck between 90m and 120m (300—400ft) long, supported some 15m (50ft) above the river by a central timber pier on an islet, and braced with four sets of inclined struts. In its day, it was a great achievement, and it survived, although possibly in a rebuilt form, until 1840."
    • P 82: COVERED BRIDGES: "Colonel Hale’s bridge was not, however, covered. This most characteristic of old American bridge profiles seems to date from 1805, when one of the most prolific and skilful of early American bridge-builders, Timothy Palmer, erected a triple-span arch-truss over the Schuylkill River in Philadelphia. Built on the site that had previously been chosen for Thomas Paine’s long-span iron bridge and a subsequently abandoned proposal for a triple masonry arch, Palmer’s “Permanent Bridge,” consisting of 45.7m (150ft) sidespans and a 59.5m (195ft) central clearance, would have remained"
    • P 83: TRUSSES in US: "The early American bridge-builders combined the arch and the truss in a variety of ways, without any clear understanding of truss action, and it is difficult or impossible now to analyse which of their structural features were carrying the loads and which were..."
    • P 84: US rail bridges; especially TRUSS bridges: "In 1847 Squire Whipple published A Work on BridgeBuilding, which for the first time brought scientific calculation into the haphazard empirical design world of the truss. Side-byside with this increased understanding of how trusses worked came a different kind of comprehension. In the United States, as in England, a growing number of rail bridge failures demonstrated the tensile inadequacy of cast iron and the material was gradually phased out in favour of wrought iron. In the 1850s, Whipple patented a bowstring type of truss in which both were used: the upper chord was entrusted to the high compressive strength of cast iron, whilst the lower chord plus the vertical and diagonal"
    • p 84: Wheeling suspension bridge
    • p 86: Niagra bridges
    • p 88: James Eads & St. Louis Suspension Bridge
    • p 90: Brooklyn Bridge Roebling
  • p 92-104 Chapter 7: TWENTIENTH CENTURY STEEL BRIDGES
    • p 92 INTRO: "The three great steel bridges built between 1870 and 1890 — the triple-arch St. Louis, the suspension Brooklyn, and the doublecantilever Forth — signalled the beginning of an epoch that continues today. Nevertheless, they marked neither the first use of steel in bridge design nor the immediate end of wrought iron. Indeed, the latter was to have a glorious swan-song. What made steel so desirable as a structural material? Cast iron — hard and thus strong in compression, but brittle and hence relatively weak in tension — includes about 3 percent carbon. Wrought iron, first made in large quantities in the 1780s by Henry Cort, has virtually the opposite properties, as Cort’s puddling process drove almost all the carbon out of the pig iron, leaving a relatively soft and malleable working material. Steels — there are many — are essentially wrought iron with certain controlled proportions of carbon replaced, together with small amounts of materials such as chromium, nickel, and manganese, variously added to impart specific properties. In general, steel combines the advantages of cast and wrought iron without the disadvantages — but before about 1850 it could not be produced in enough quantity for large-scale industrial use. An Austrian engineer, Ignaz von Mitis, was the first to use steel in a bridge — for the hanging eyebars of a slender suspended span over Vienna’ Danube Canal in 1828, but this was rare before the mid-century flurry of new steel-smelting processes, initiated in the USA by William Kelly and in England by Henry Bessemer and Robert Mushet. In the 1860s, William Siemens and the Martin brothers introduced improvements to the processes in England and France; and the same decade saw the first small steel bridges completed in Europe, although at first it was difficult to control the quality. In 1865, however, Julius Baur patented chrome steel in the USA, and it was this alloy that Eads used for the St. Louis Bridge. His quality and quantity requirements were so unprecedentedly rigorous that negotiations for supply were both protracted and acrimonious, but they pulled bridge-building steel out of its infancy and changed it from wrought iron’s uncertain sideline into an industry in its own right. The first all-steel bridge came in 1879, five years after the completion of the St. Louis, when another pioneering American engineer, General William Sooy Smith, used a new type of steel, developed by A. T. Hay, to build five 94.8m (3k1ft) Whipple trusses to carry a railroad across the river at Glasgow, Missouri. During construction, part of the timber scaffolding collapsed, and one whole span crashed into the river. When it was recovered, it was found to exhibit not the slightest sign of brittle fracture. Even so, the Missouri Bridge did not usher in a general move away from wrought iron. "
    • p 93: Some steel bridges in France & EUrope
    • p 93: STEEL ARCH: " In 1897 John Roebling’s pioneering Niagara suspension bridge was replaced by a steel arch, and in the following year a new record for steel arches was set by the nearby 256m (840ft) Niagara-Clifton Bridge, which was to succumb to an ice-jam in 1938. In France the first large steel bridge was the Viaur Viaduct, completed in 1898, with a central 220m (721 ft) cantilever span; and one of the most enterprising structures from the beginning of the 20th century was built in the heart of Africa. The site was even more spectacular than Niagara — the Zambezi Gorge below Victoria Falls. Here, in 1907, an English engineer named Ralph Freeman built out the two halves of a 152m (500ft) steel arch from the sides of the Gorge, tied back by cables until they met"
    • Disaster on Disaster: The Quebec Bridge, Canada 94
    • The Carquinez Strait Bridges, San Francisco, USA 96
    • The Howrah River Bridge, Calcutta, India 98
    • Hell Gate Bridge, East River, New York, USA 100
    • Australian and American Rivalry: Sydney and New York 102
    • Renaissance of the Box-girder, Europe 104
  • Chapter 8: pp 106-124 STEEL SUSPENSION BRIDGES
    • P 106: INTRO: "During the first half of the 20th century, an unparalleled conjunction of need, will, and resources ensured that the greatest activity in long-span bridge-building took place in the USA, supremely in the development of the suspension principle for the very longest distances. In this, the eclipse of the railroad by road traffic played an important part. Despite the success of Roebling’s Niagara and Brooklyn Bridges, the extra rigidity of arches, trusses, and cantilevers made them more immediately suitable for railroads. The mushrooming need for road bridges in the early 20th century left behind such extreme concentrations of load, allowing enterprising designers of suspension bridges to extend the limits of the possible, both in span length and in the ratio between the span and the depth of the deck, although ultimately not without cost. For nearly 50 years after the completion of the Brooklyn Bridge, these limits were nudged gently forward. Of all American cities, New York gave the greatest opportunities to bridge-builders, as it needed many links between its separate parts across the ..."
    • P 106-107: INTRO CONT: "Thereafter, the trend toward slenderness, grace, and economy gathered momentum. Gustav Lindenthal, who, as city bridge designed New York’s next major suspension bridge. This was the Manhattan (1909), giving New York’s East River three suspension crossings in as many kilometres. The structural calculations were carried out by Leon Moisseiff, using for the first time the “deflection” theory, developed in the 1880s by the Austrian engineer Joseph Melan, which demonstrated that excessively deep trusses were unnecessary and that stability under dead load and live load could be maintained with much more slender and flexible decks and towers. David Steinman, who translated Melan’s work on his deflection theory into English in 1913, described the Manhattan Bridge as the first “to exemplify modern suspension bridge techniques.” ... A new development for medium spans was the self-anchoring eyebar chain, first used in a 184m (605ft) Rhine bridge at Cologne (1915), in which the chain terminated at the ends of the stiffening truss rather than going into ground anchorages, so that the truss took the tension like a bowstring girder. "
    • p 108 George Washington Bridge NY
    • p 110 San Francisco bridges
    • p 112 Golden Gate Bridge
    • p 114: Galloping Gerty - Tacoma bridge?
    • p 116: Mackianac Straits brdige
    • p 118 Verrazanno Narrows Bridge NYC
    • p 120 Forth Bridge Scotland (new Forth bride()
    • p 122 Tagus Bridge Portugal
    • p 124 Severn Bridge UK
  • Chapter 9: Advances in Concrete Bridges p 126 - 144
    • p 126 INTRO "The invention of “concrete” undoubtedly long predates the Romans’ first use of it in around the 2nd century BC, but the Roman concrete containing lime and pozzolana — the volcanic powder that gave it both strength and waterproofing — virtually disappeared with the Empire. Although water-soluble lime mortar was used throughout the Middle Ages, knowledge of the Roman-type ~ concrete virtually disappeared until the latter half of the 18th century, when, for example, John Smeaton developed new waterproof pozzolanic cements and used them to set the masonry of the Eddystone Lighthouse. Then, in the early 19th century, both natural cement and the new artificial “Portland” cement, which was invented and patented by Joseph Aspdin in 1824, became widely used for pointing and facing masonry, and for the mass concrete foundations in civil engineering works. Experiments with “concrete” were also being carried out in France. In 1831 an architect named Lebrun put forward an unsuccessful proposal for a concrete bridge over the River Agoat. From about the middle of the 19th century, however, bridges in mass concrete began to be built in Europe and the USA and, as it was an “artificial stone,” designs naturally followed the timehonoured shape of masonry bridges — the arch. The first major example in Britain was surprisingly late: the Glenfinnan Railway Viaduct in Inverness-shire, Scotland, was constructed in 1898. Only the fact that the material had not been disguised with stone cladding or imitation voussoir markings distinguished it visually from hundreds of masonry prototypes. The essential concept behind the reinforcing of concrete is the production of a composite material that combines the high tensile strength of steel (or originally wrought iron) with the compressive strength of mass concrete, the presence of metal rods negating the concrete’s low strength in tension. In the first half of the 19th century, iron was occasionally embedded in concrete to strengthen it; Thomas Telford himself used iron ties in the Menai Bridge’s concrete abutments, and later others experimented with floor members and even the hull of a boat. But the man generally credited with liberating the true structural potential of reinforced concrete was a French gardener named Joseph Monier. In 1867 Monier took out a patent for making plant tubs out of cement mortar strengthened with embedded iron netting. Other patents followed, first for railway sleepers, and then various building applications, including bridges: he built a ... arch in 1875."
    • P 127 INTRO CONT: "In the USA, quite independently, a bolt manufacturer named William Ward also experimented with structures of iron buried in concrete; and a lawyer and engineer, Thaddeus Hyatt, became the first to analyse the stresses in concrete beams reinforced with iron. The Viennese Joseph Melan also brought scientific analysis to bear, developing an arch-based bridge design and building several examples in which a steel arch acted as centering for the poured concrete and then became its reinforcement when it hardened. Ward and Hyatt both realized that in a beam of whatever section, gravity plus dead and live loading will ensure that the bottom part is in tension and the top in compression, and that therefore any reinforcement should be concentrated below, where it is most needed; and Hyatt seems to have been the first to use this principle to devise a beam with a T-shaped cross-section, having flat wrought-iron strips secured on edge lengthways beneath a concrete slab. Credit for the practical development and first widespread use of reinforced concrete in bridges goes principally to Francois Hennebique in France and G. A. Wayss in Germany. Hennebique extensively researched the design of T-beams in the 1880s, substituting steel for wrought iron and bending up the ends of the reinforcement bars near the supports into the “compression zone,” paralleling earlier work by Hyatt. Meanwhile, Wayss had bought the German rights to Monier’s patent. By the mid-1890s, his firm, Wayss & Freitag, had built numerous reinforced-concrete archbridges, some with spans exceeding 30m (100ft), but their designs were still relatively heavy, conservative imitations of masonry. Hennebique took out patents in 1892 and, through his widespread network of contracting agents, ensured that his designs became structures. By 1900 there were over 3,000 of them, including about 100 bridges. They were the most forward-looking yet, and they had begun to exploit the material’s potential for strength and slenderness. Hennebique’s most notable bridge before the turn of the century was the Pont de Chatellerault (1899) over the River Vienne in France. It has two segmental-arch spans of ..... A year earlier, the Swiss engineer Robert Maillart had constructed his first bridge while still working as an assistant to Hennebique. This, the first reinforced-concrete bridge by the man many still consider to be the greatest artist in the field, was the modest Stauffacher arch over the Sihl River in Zurich. Although it is stone-clad and ornamented to a degree that makes it unrecognizable a a Maillart bridge, there is a slender three-hinged "
    • p 128 Maillart Switzerland
    • p 130 Tunkkchannock Viacduct Penn
    • p 134 Fyeyssinet & Plougastel Bridge France
    • p 136 McCullugh Oregon
    • P 140-141 Presstressed Concrete " Any building (or bridge) material can be “prestressed.” A single rope across a river, stretched from one tree to another, has tensile stresses locked into it to reduce its flexibility. The principle of prestressing concrete, expressed at its simplest, is much the same: longitudinal steel strands in a concrete beam are stretched or tensioned and then anchored to the ends of the beam. This neutralizes the tensile forces created by dead, live, and environmental loads — and thus the propensity of concrete to crack — by the application of greater compressive forces. Far more effectively than with simple reinforcement, prestressing maximizes concrete’s strength in compression and compensates for its weakness in tension. An American engineer named P. A. Jackson was probably the first to formulate the idea of prestressing concrete when in 1872 he patented a system of passing iron tie-rods through blocks and tightening them with nuts. Others experimented in subsequent decades, including Eugéne Freyssinet, who observed the action of creep for the first time when he used steel bars under tension to anchor the ends of his test arch for the Veurdre Bridge. The technique of jacking the halves of an arch apart, which Freyssinet brought in as an expedient on the Veurdre Bridge to stave off disaster, was incorporated as an integral part of the design on two major bridges — the Candelier Bridge over the Sambre (1921) and the Saint Pierre du Vauvray (1923), at the time the world’s longest concrete arch-span at 131.8m (435ft). In both, he jacked the arches off the centering in two halves and inserted new concrete at the crown to withstand the effects of shrinkage. For Plougastel, however, he needed a precise evaluation of the extent of creep. He studied the phenomenon, got an answer, and concluded that prestressing with high-strength steel bonded to the concrete was a viable structural .... Prestressing itself can be carried out in two different ways. In pre-tensioning, the concrete is cast around the steel cables with them already under tension; when it hardens, it is released from the mould and the wires severed from their ties, the bond between cables and concrete ensuring that most of the pre-tensioning is retained. In post-tensioning, however, the concrete is poured with voids incorporated, so that after it has hardened, the cables can be threaded through, stretched, and anchored. The former is more commonly used for the precast production of building elements in the factory, the latter for casting larger members in situ. Both are used in bridge-building,.... Alongside the evolution of these techniques, the composition of concrete itself has undergone steady development, as have the design of formwork systems (with their consequences for the final appearance of the concrete surface) and the methods for compacting it by vibration before setting."
    • p 144 Concrete bridges in Australian & Croatia
  • p 146 -156 Chapter 10 Cable-stayed bridges
    • p 146 INTRO: "Cable-stayed designs — in which bridge decks are directly connected to supporting masts by straight cables — burst onto the scene soon after the Second World War. In 1952 Fritz Leonhardt designed a “family” of three cable-stayed bridges over the Rhine at Diisseldorf, the first of which, the Theodor Heuss or North Bridge, with main and side-spans of 280m (919ft) and 108m (354ft), was completed in 1958. By then, the smaller Stromsund Bridge in Sweden, designed by another German, Franz Dischinger, had already been open for two years [p 154: was completed 1955 or 56]. Both were of steel. No matter which is regarded as the first, the concept was hardly new. The idea of stabilizing and/or supporting a beam by ropes from a vertical support began with the booms, rigging, and masts of ancient Egyptian sailing ships. Some primitive bridges have decks stayed from above by ropes or vines; and the 16th-century Pons Ferreus illustrated by Verantius was as much a proto-stayed bridge as a suspension design. Indeed, “cable-stayed” is not a long way from “cable-supported,” and the history of suspension bridges is threaded with a less prominent, but still noticeable, stayed element. John Roebling’s three major designs — Niagara, Cincinnati, and Brooklyn — incorporated networks of diagonal wire stays radiating directly from the tops of their towers to the decks, doubling up on the work of the main cables and their suspension wires. The stays helped both to support and stiffen the decks; and in the case of the Brooklyn Bridge, Roebling averred that “the floor, in connection with the stays, will support itself without the assistance of the cable.” Paradoxically, although Roebling regarded wire-staying only as a necessary back-up to the suspension system, he was probably the only designer before the advent of modern structural analysis who might have been capable of a successful, empirically designed stayed structure, but it seems that he never contemplated such a project. The first such design in modern times is attributed to a German named Léscher, who in 1784 published an illustrated account of a stayed bridge made entirely of timber — including the stays. In 1817 two British engineers, Redpath and Brown, built a small trussed footbridge stayed by wires from iron towers; and only a few years later, two Frenchmen, Poyet and Navier, independently proposed designs remarkably prescient of present-day cable-stayed bridges. "
    • p 147 INTRO CONT (first modern cable stay): "In 1938 Dischinger incorporated stay cables in a railroad suspension bridge near Hamburg, when he realized that he could achieve stiffness and stability if the cables were made of highstrength steel wires under considerable stress. Leonhardt was also developing a concept for “orthotropic” steel decks — stiffened along the span length by longitudinal girders beneath the deck plates. After the war, Diisseldorf and Strémsund saw the first practical results of their work, which embodied all the virtues of safety, aesthetic quality, economy, and simplicity. The way was open for a sweeping success story in cable-stayed designs, ranging from"
        • Google says: "The first modern cable-stayed bridge is considered to be the Strömsund Bridge in Sweden, completed in 1955 or 1956. While earlier designs and examples existed, such as the one by Fausto Veranzio in 1615, the Strömsund Bridge was the first to be built using modern techniques and materials,"
    • p 148 Mracaibo
    • p 149 Alex Fraser BC Canada
    • p 150 Queen Elizabeth II bridge London
    • p 152 Skarnundet Bridge Norway
    • p 154 Variious Cable stay designs etc
  • p 158-200 CHapters 11 and 12: various modern bridges from 1990 to 2010

Watson 1937 Legend & History source

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  • p 77: "A very early type of bridge featured in warfare was the ancient pontoon or floating bridge. The earliest mention of a bridge in China, found in the Canon of Poetry, is of a bridge of boats."
  • p. 77 "Xerxes’ bridge over the Hellespont is the most famous. It was built in 480 B. C. by the Persians when they attacked the Greek..."
  • p 76-101 - Gives examples of "war bridges" that played key roles in historical battles. Interesting, but probably too minor for the Br article.
    • p 84 Trajan's bridge "One of the most famous of the Roman War Bridges was that built across the Danube at the ‘Iron Gate’? by the Emperor Trajan, in order to attack the barbarians to the north; however, it is curious to note that a little later it was destroyed by order of the Emperor Hadrian because the tables had been turned and the barbarians were using it to attack the Romans. One Roman historian denies this account and attributes the destruction of the bridge to jealousy on the part of Hadrian who resented its fame as “the wonder of the world.” The structure is depicted on the Arch of Trajan at Rome, as consisting of twenty spans of timber arches supported on masonry piers: the design is attributed to one Appolodorus of Damascus."
  • p 147-165 - A list of important historical bridges built for "peaceful purposes", including roman aqueducts, etc
    • p 148 "Throughout all recorded history there occur references to famous bridges, and certain types of structures have been characteristic of the contemporaneous civilization. Bridges were commonly built by prehistoric man, as evidenced by the remains of the timber pile trestles of the Lake Dwellers, preserved for ages by immersion in water; by the bamboo suspension bridges of eastern Asia, still common; by those structures of hide ropes constructed by the Incas in South America described by Darwin in the **Voyage of the Beagle”; by the so-called *‘Clapper Bridges,’ rude structures of flat stone slabs supported upon stone piers, found in England; and by the better built ones found in China. Some of the early bridges mentioned in history were doubtless of this latter type or more commonly composed of timber beams on stone piers, such as the bridge of Semiramus over the Euphrates, built over two thousand years before Christ. It is well known that the Persians had perfected a comprehensive system of improved roads connecting the principal cities of the Empire as early as 500 B. C. It seems quite probable that many such bridges were included in the system as well as bridges of the pontoon or boat type such as those described by Xenophon in the “Retreat of the Ten Thousand” and such as the famous bridge of Xerxes over the Hellespont."
    • p 149: CHina "Meanwhile bridges were well known in China, as proven by the Chinese character for a bridge, Ch’iao, which dates back to about 1000 B. C. That the Chinese were early acquainted with the pontoon bridge also seems probable for an ancient proverb says “tin the hold of the floating bridge he has an interest.”? The compartments of the old boats which constituted the floating bridges were pre-empted by beggars for their dwellings. The expression signifies that he who has an interest in the “floating bridge” has come to poverty at last."
    • p 149-150 "The Roman travelled and conquered mostly by land, and Roman civilization required easy and rapid means of communication that could only be obtained by good roads and bridges. At one time the system of Imperial Roman roads comprised over 50,000 miles of improved highways and hundreds of bridges, many of which exist to this day and still serve traffic. It has been stated that the Roman resident of northern Britain could travel all the way to Rome without fording a stream,—his progress on an improved highway being only interrupted by the passage of the Channel."
    • P 150 "The typical Roman bridge was the pile and beam timber structure exemplified by the Pons Sublicius at Rome and the bridge over the Rhine so accurately described by Caesar in his Commentaries. Such bridges are known to have existed in Roman times at London and at Newcastle in England. One of the most famous of the Roman bridges, that over the Danube at the Iron Gates, erected under the Emperor Trajan, consisted of timber arches supported upon masonry piers, probably quite similar to many of our early American timber bridges. Although, undoubtedly, most Roman bridges were of timber, the Roman genius is best illustrated by its stone arch bridges and aqueducts. Bold in conception and massive in construction, they well typified the power and majesty of Imperial Rome. Decoration was seldom used. Asa rule, the roadway was narrow as were the roads themselves, yet the famous Alcantara Bridge in Spain, built under the Emperor Trajan, has a width of about 26 feet. Footwalks were seldom used"
    • P 151: Roman Aqueduct: "The pre-eminent Roman Aqueduct is the Pont-du Gard near Nimes, France, attributed to the Emperor Agrippa and the year 14 A.D. The total length of this aqueduct is some forty kilometers, the aqueduct bridge itself being about 262 meters long and 51.7 meters high and consisting of three tiers of arches. The warm yellowish color of the stone used and its natural setting make the structure a favorite subject for artists and writers. Jean Jacques Rousseau says in his Confessions, published in 1793:"
    • p 163 "The Romans were not the only peoples that built permanent bridges, however. On the ancient highway from Galilee to Jerusalem are several stone arch bridges antedating the Christian era, over which Jesus himself must have trod,"
  • p 209 quote from FDR: The New York Times, Oct. 18, 1931. “There can be little doubt that in many ways the story of bridge building is the story of civilization. By it we can readily measure an important part of a people’s progress.”
  • pp 209-229: History of HUGE advances in bridge building from 1830 to 1930
  • Concludiosn: p 231-232 " Poets [are]... prophets or seers. In this capacity they have developed the symbolic purpose of the bridge, an image that has become so significant in literature as to be a thought-pattern, an actuality whereby an idea, common to all ages and civilizations, may be grasped and understood. As such it recurs continually like a theme through religion, philosophy, prose or poetry; it is still effective today, as Thornton Wilder’s Bridge of San Luis-Rey and Willa Cather’s Alexander’s Bridge testify. For instance, in the latter work the hero, a successful engineer, builds a bridge which is, like himself, apparently sturdy but inwardly weak. As a result, the bridge collapses with the designer upon it. From the rainbow bridge to the Golden Gate span is a very long way, indeed; yet they have this in common, this underlying wellspring of their existence conceived in the mind of man. This bridge symbolism is inherent: its beginnings are too far back in the dim, pre-historic ages to trace clearly, and its end is not yet in sight. Although a bridge is, obviously, a means whereby an obstacle or obstruction is overcome, it takes many well-known forms and shapes, as we have seen. The variations and external appearances are only decorations built upon the fundamental spiritual conception. The symbolism with these variations has entered all records of civilization-art, literature, history and folk-lore."
  • p 232: Brides in art/paintings: " Examples of the powerful effect of the bridge upon the visual imagination can be best found in the works of painters. The conception of the Rainbow Bridge in the Nibelungenlied which leads to Walhalla has caught the imagination of many artists, among them Hugo Braune. Franz Hals drew one of his typical Dutch figures lazily smoking his pipe above a bridge, while another Dutch artist, Von Canal, painted Rembrandt’s home with the lovely stone arches gracefully bending over the river. Rubens has a painting of a bridge in the ‘Journey to the Bridge of Ce’’, hanging in the Louvre. Then, among the moderns, are Van Gogh with his ‘Le Pont d’Austerlitz” and the “Railway Bridge”, and the etchers John Fullwood, Simon and Figura, all of whom seem to be very fond of bridge subjects. There are, of course, many more charming pictures that successfully create the feeling of the bridge: the authors know of two etchings, for instance, of the bridge of Mostar in Jugoslavia that are beautiful idealizations of this old Roman arch—perfect in that capacity to repro..."

Sub-articles

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Outline

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  • Image Gallery

Images

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Books

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  • order books from amazon
    • $75 Design of Highway Bridges: An LRFD Approach 4th Edition
    • [free on IA]s How to Read Bridges: A Crash Course In Engineering and Architecture Paperback
    • $200 Simplified LRFD Bridge Design
    • [childrens book?] Unveiling the Fascinating History and Engineering Marvels of Bridges
    • $32 Bridges: A History of the World's Most Spectacular Spans
  • Research access to ASCI JBE - some are free e.g. https://ascelibrary.org/doi/10.1061/JBENF2.BEENG-7568 ... not clear which are free or not!?!?!
  • ASCE books : https://www.asce.org/search#q=bridge&sort=relevancy&f:contenttype=[Books] ... most around $40 for e-book
    • [free on IA] History of the Modern Suspension Bridge: Solving the Dilemma between Economy and Stiffness
    • [free on IA] In the Wake of Tacoma: Suspension Bridges and the Quest for Aerodynamic Stability
    • [free on IA] Landmark American Bridges
    • $60 Beyond Failure: Forensic Case Studies for Civil Engineers
    • Handbook of Concrete Bridge Management
    • Bridge Decks: Design, Construction, Rehabilitation, Replacement
    • Guidelines for the Design of Cable-Stayed Bridges
    • Assessment of Performance of Vital Long-Span Bridges in the United States
    • The Colossus of 1812: An American Engineering Superlative
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