Impact of LRFD Specifications on Design of Texas Bridges Volume 1: Parametric Study

The Texas Department of Transportation (TxDOT) is currently designing highway bridge structures using the American Association of State Highway and Transportation Officials (AASHTO) "Standard Specifications for Highway Bridges", and it is expected that the agency will transition to the use of the "AASHTO LRFD Bridge Design Specifications before 2007". This is a two-volume report that documents the findings of a TxDOT-sponsored research project to evaluate the impact of the Load and Resistance Factor (LRFD) Specifications on the design of typical Texas bridges as compared to the Standard Specifications. The objectives of this portion of the project are to evaluate the current LRFD Specifications to assess the calibration of the code with respect to typical Texas prestressed bridge girders, to perform a critical review of the major changes when transitioning to LRFD design, and to recommend guidelines to assist TxDOT in implementing the LRFD Specifications. A parametric study for AASHTO Type IV, Type C, and Texas U54 girders was conducted using span length, girder spacing, and strand diameter as the major parameters that are varied. Based on the results obtained from the parametric study, two critical areas were identified where significant changes in design results were observed when comparing Standard and LRFD designs. The critical areas are the transverse shear requirements and interface shear requirements, and these are further investigated. In addition, limitations in the LRFD Specifications, such as those for the percentage of debonded strands and use of the LRFD live load distribution factor formulas, were identified as restrictions that would impact TxDOT bridge girder designs, and these issues are further assessed. The results of the parametric study, along with critical design issues that were identified and related recommendations, are summarized in Volume 1 of this report. Detailed design examples for an AASHTO Type IV girder and a Texas U54 girder using both the AASHTO Standard Specifications and AASHTO LRFD Specifications were also developed and compared. Volume 2 of this report contains these examples.

• Record URL:
  http://tti.tamu.edu/documents/0-4751-1-V1.pdf
• 
• Supplemental Notes:
  • Project Title: Impact of LRFD Specifications on the Design of Texas Bridges. Report Date: September 2006; Published Date: December 2006.
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 3135 TAMU
  College Station, TX  United States  77843-3135

  Texas Department of Transportation

  Research and Technology Implementation Office, P.O. Box 5080
  Austin, TX  United States  78763-5080

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Hueste, Mary Beth D
  • Adil, Mohammed Safi Uddin
  • Adnan, Mohsin
  • Keating, Peter B
• Publication Date: 2006-12

Language

• English

Media Info

• Media Type: Print
• Edition: Technical Report
• Features: Appendices; Figures; References; Tables;
• Pagination: 390p

Subject/Index Terms

• TRT Terms: Bridge design; Bridges; Calibration; Girder bridges; Guidelines; Load and resistance factor design; Load transfer; Parametric analysis; Shear properties
• Identifier Terms: AASHTO LRFD Bridge Design Specifications; AASHTO Standard Specifications for Highway Bridges; American Association of State Highway and Transportation Officials
• Geographic Terms: Texas
• Subject Areas: Bridges and other structures; Data and Information Technology; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 01044300
• Record Type: Publication
• Report/Paper Numbers: FHWA/TX-07/0-4751-1 Vol. 1, Report 0-4751-1 Vol. 1
• Contract Numbers: Project 0-4751
• Files: TRIS, USDOT, STATEDOT
• Created Date: Mar 13 2007 8:22PM