Steel plate girder diaphragm and cross bracing loads.

Details

• Creators:
  Gull, Jawad H. ; Azizinamini, Atorod
• Corporate Creators:
  Florida International University
• Subject/TRT Terms:
  • Plate girders
  • Steel bridges
  • Bridge design
  • Braces
  • Stiffness
  • Diaphragms (Engineering)
  • Structural connection
  • Traffic loads
  • Finite element method
• Publication/ Report Number:
  BDK80-977-20
• Resource Type:
  Tech Report
• Geographical Coverage:
  Florida
• Corporate Publisher:
  Florida. Dept. of Transportation
• Abstract:
  The wide spectrum of options available to designers for analyzing and determining cross-frame forces can be a ; source of problems because different options may not result in similar solutions. The main objective of this ; project was to develop a set of recommendations and procedures and instructions to address analysis, design, and ; construction issues related to braces in steel I-girder bridges. ; Different methods that can be used to calculate brace loads are categorized and discussed in detail to identify the ; strengths and limitations of each method. The traditional 2D-grid analyses that are often used by commercial ; software packages ( such as MDX and DESCUS) does not take into account the full warping stiffness, resulting in ; underestimation of torsional stiffness of the girders. Although improved 2D-grid analyses may result in an ; improved representation of the full warping stiffness, these models are generally applicable to a no-load fit ; condition for cross-frames or diaphragms. The procedure by which 2D-grid analyses can be used for calculating ; cross-frame forces and other structural responses of bridges detailed with dead load detailing methods (erected fit ; and final fit) are described. It has been found that performance of improved and traditional 2D-grid analyses also ; depends on the framing layout (contiguous or staggered). Improved 2D-grid analyses are preferred for calculating ; the cross-frame forces because of the satisfactory performance for most of the framing layouts. A relatively ; simple method of simulating lack-of-fit is introduced in this report which makes use of models using three-dimensional (3D) finite element method (FEM). Although past studies have recommended using initial strain to ; simulate lack-of-fit in the cross-frames, this method can be tedious and complex. The proposed method makes ; use of element birth and death techniques to activate or deactivate the cross-frame elements to obtain a measure of ; the force or deformation at specific desired stages. The element birth and death method is generally more simple ; than the initial-strain methods with the essentially the same level of accuracy. Finally, different options for ; framing layouts, detailing methods, cross-frame configurations, and design methods for sizing the cross-frame ; members are discussed.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27738/dot_27738_DS1.pdf
• File Type:
  [PDF - 4.94 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:03d65c917b048f5c67056dd5ef7b5f7c282fa8f90c64d207d25072559c266f03