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Steel Bridge Fabrication Technology Study Scan

Amplifying Questions

  1. Application of Innovative Structural Shapes and Bridge Configurations
  2. Applications of New Materials
  3. Techniques for Cutting and Joining Steel Members
  4. Automated Recording Procedures for Shop and Field Inspection
  5. Integrated CAD/CAM Procedures and Robotic Fabrication
  6. Additional topics of Interest
  1. Application of Innovative Structural Shapes and Bridge Configurations

    1. What new, cross-sectional shapes and overall geometry have you used in bridges?

    2. Is there a preference for open or closed shapes? Why?

    3. Please respond to the following questions in terms of
      1. cost effectiveness,
      2. good or bad performance,
      3. any special design criteria required:
        1. Have you constructed any bridges using corrugated steel webs?
        2. Have tubular members been used in truss or girder elements?
        3. Are single box bridges used?
        4. Have any modular steel bridges been developed?
        5. Are steel piers used as much now as in the past?
        6. Are steel bridges used with integral pier caps?
        7. Are there innovative bridge decks?
        8. Where are orthotropic steel decks used?
        9. Have any steel bridge configurations been developed to enhance fatigue resistance to minimize the need for designs controlled by fatigue factors?
        10. Have innovative, seismic-resistant steel bridges been developed?

    4. Do standardized steel bridges exist?
      1. What type and span?
      2. Are typical bridge design details standardized in your region? By whom?

    5. What innovations have you made in the construction of short-span (<40 m) to medium-span (<80 m) steel bridges? What is your experience with costs and trends?

    6. Has prestressing been used in the construction of steel bridges?
      1. Has it been cost effective and does it provide good performance?
      2. Are there special design criteria?

    7. How do rolled "I" shapes compare with welded plate girders?

    8. What is the trend in the use of bracing and diaphragms?
      1. What standards exist?
      2. Are removable diaphragms used?

    9. Are steel castings used for connections?
      1. What materials are used?
      2. What specifications have been developed?

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  2. Applications of New Materials

    1. How are higher-strength steels (485 MPa to 800 MPa yield strength) being used?
      1. What are the future trends for these steels?
      2. Are all of the higher-strength steels produced as TMCP or is Q&T material used?
      3. What toughness, sampling frequency, and locations are used?

    2. Are tapered (thickness) plates used very often?
      1. Are there thickness-tolerance specifications?
      2. What is the availability of such plates?
      3. What is their relative cost?

    3. How much weathering steel is being used versus, painted steel?
      1. Are there any special fabrication requirements?
      2. Are there any improvements being made to basic weathering?
      3. What do you see as the future use of weathering steels?
      4. Are special joints and details used?
      5. Is staining a problem? How do you manage it?

    4. What is the maximum thickness of plate used in steel bridges?
      1. Are there differences for pedestrian, vehicular, and railroad bridges?
      2. Are there standard codes?
      3. What is the basis for the criteria that are used?
      4. Is toughness considered when determining thickness limits?

    5. What are the actual levels of P and S used in bridges? Is calcium treatment used or specified on all bridge steels? To what extent is vacuum degassing used?

    6. What organization(s) is responsible for writing the specifications for bridge steel?
      1. Are steels certified to more than one specification? Is this required by the owner? Does this practice cause fabrication problems?
      2. What substitutions are allowed for steels specified in contract documents?

    7. Who is responsible for encouraging new steel development?

    8. Have advanced composite materials been used in conjunction with structural steel to construct bridges?

    9. Is undermatched weld metal used for design and fabrication?
      1. How is it being used?
      2. What is the range of applications?

    10. What use is made of stainless and clad steels in bridge structures?

    11. What new steels are used for pins, bolts, and bearings?

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  3. Techniques for Cutting and Joining Steel Members (in the Shop/Field and Field Erection Techniques)

    1. What recent innovations have been developed in the areas of welding consumables, equipment, and processes?
      1. Are high-energy welding processes (i.e., electron beam, laser or other) in common use?
      2. Are high deposition rates used?
      3. Is electroslag or electors welding used? What are the requirements? What thickness?
      4. Are multiword, sub-arc systems being used? How many wires? What type of power?
      5. Is solid wire Mig/Mag weld permitted?
        1. Is short circuiting welding permitted? Under what conditions?
        2. Is pulsed-arc Mig welding permitted? Under what conditions?
      6. What other processes are used?
      7. Is flux-core self shielded, flux-core gas shielded or metal core welding used?
      8. What percentage of welds are made by these different processes?
      9. What is your planned future use?

    2. What cutting systems are in common use?
      1. What is used in the field?
      2. Do you weld directly on the cut surface?
      3. Are thermal cut holes used with or without further treatment?

    3. Is automated handling of materials for assembling member elements being used in the shop? In the field?

    4. Are there in-process distortion controls?
      1. How does material variability influence this process?
      2. How is welding distortion predicted?
      3. What dimensional checks are used?
      4. How is drilling accounted for?

    5. What cambering and heat-straightening techniques are used?
      1. Is the process automated?
      2. Where are the control points?

    6. Are in-process NDT testing and monitoring techniques being used to assess weld quality?
      1. How often?
      2. What statistical principles are applied?

    7. What are the fit-up requirements for pre-assembly and construction?
      1. Are shop fit-up requirements imposed by owners?
      2. Is this a partial or full fit-up?
      3. What does the fabricator do in the shop to ensure compliance?
      4. Are computerized preassembly methods permitted?
      5. What procedures are used to ensure success?
      6. What has been your experience with this method?
      7. Are special criteria applied to horizontally curved girders?

    8. Is field welding used to any extent?
      1. To what extent is the process automated?
      2. How are consumables stored on site? (c) What processes are used?

    9. How are weld procedures and personnel qualified?
      1. Are statistical methods employed?
      2. Are welders who are qualified for other applications (i.e., pressure vessels, ships) accepted for bridge work without additional qualification?

    10. How are weld acceptance procedures applied?
      1. Are fitness for service criteria allowed?
      2. Who is responsible for Quality Control (QC)/Quality Assurance (QA) of the fabrication and erection?
      3. Who develops the standard?

    11. What role does automation play in the assembly and welding of orthotropic decks?

    12. What are the size and length limitations or restrictions in fabrication? Is this controlled by transportation or construction limitations?

    13. Are structural adhesives being used to join steel components?

    14. Have electrodes maintained compatibility with base metal weldability?

    15. What procedures are used for plate and shape bending?
      1. What thickness and radius criteria are applied for cold bending?
      2. Do fracture toughness requirements impact these procedures?
      3. What role does the type of steel play?

    16. What kind of pre- and post-welding treatments are used? What role do ceramics, metal spacers, back-gouging, peening or other "improvements" have in these?

    17. What percentage of field splices are bolted? What percentage are welded?
      1. If bolted splices are used, are special treatments or sealants required for corrosion protection?
      2. Are these treatments specified or used at the discretion of the fabricator?

    18. Are there special installation requirements for anchor bolts?

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  4. Automated Recording Procedures for Shop and Field Inspection

    1. Is automated, ultrasonic scanning of groove welds performed in the shop? Would it be possible to see this demonstrated during our site visit?

    2. How is the integrity of the inspection records maintained?

    3. Who is responsible for the data base input?

    4. Are automated inspection procedures used in the field? How often?

    5. How are fillet welds inspected?

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  5. Integrated CAD/CAM Procedures and Robotic Fabrication

    1. How are design drawings translated into shop drawings?

    2. Are electronic design documents used in the bidding process? Are they used for fabrication?

    3. How are shop drawings approved?
      1. Are they electronically submitted? If so, how is the approval given?
      2. How are shop-generated machine codes checked?

    4. How are robots monitored? How often?

    5. What are the requirements for qualification of operators of robotic and automated machinery?

    6. What types of automated field erection are used?

    7. What has been your experience regarding the measurements used to monitor the transition from old methods to automated, computer-integrated manufacturing in terms of-
      1. direct and indirect labor ratios.
      2. man-hours per ton.
      3. efficiency improvements.
      4. cost differentials.
      5. capital differentials.

    8. What direct labor cost increases or decreases occur as a result of automation?

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  6. Additional topics of Interest

    1. Are there committees established to identify, review, and promote technological advances at different government or authority levels (i.e., regional or national)?

    2. Is heat straightening used to assist repair of damaged bridge members?

    3. What bearings are being used?
      1. Are comparable bearings used for steel and concrete bridges?
      2. Are they fabricated in the shop or by specialty manufacturers?
      3. What controls the type selection?
      4. What do you see as trends for the future?

    4. How closely do design engineers work with fabricators/erectors/inspectors prior to fabrications and erection?

    5. What part of the design/fabrication/construction process has the potential for the most improvement?

    6. What measures are being taken to make steel bridges more competitive?

    7. What percent of your budget is invested in research and development? What government incentives are provided?

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