Proposed Modification to AASHTO Cross-Frame Analysis and Design

BACKGROUND Developments in bridge design and analysis in recent years have created the need for improvements to cross-frame analysis and design for steel girder bridges. In the past, the configuration of cross-frame systems was generally based upon standard designs in which member sizes and layouts were dependent upon geometry and minimum member cross-section requirements. The opportunities for improvements to cross-frame analysis and design cover a variety of topics including: (1) improved definition of fatigue loading for cross frames in curved and/or severely skewed steel girder bridges analyzed using refined analysis methods; (2) implementation of stability bracing strength and stiffness requirements in the context of AASHTO Load and Resistance Factor Design (LRFD) bridge design; and (3) additional guidance for adjustment of the effective stiffness of cross-frame members in refined analysis models to reflect the influence of end connections on cross-frame member stiffness. Addressing these topics could result in a dramatic improvement in reliability and economy of cross frames for steel I-girder bridges. OBJECTIVE The objective of this research is to propose modification to the AASHTO LRFD Bridge Design Specifications to provide quantitatively based guidance on: (1) the calculation of the fatigue design forces in cross frames in steel I-girder bridges; (2) the calculation of strength and stiffness requirements for stability bracing; and (3) the influence of cross-frame member end connection upon the cross-frame stiffness. Accomplishment of the project objective will require at least the following tasks. STATUS: Phase I report is published as NCHRP Research Report 962. The final report for Phase II has been received. A publication decision is pending for Phase II.

• Record URL:
  http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=4194
• Supplemental Notes:
  • Phase I report is published as NCHRP Research Report 962, Phase II is completed and will be published as NCHRP Report.

Language

• English

Project

• Status: Completed
• Funding: $590,000
• Contract Numbers:

  Project 12-113

• Sponsor Organizations:

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  American Association of State Highway and Transportation Officials (AASHTO)

  444 North Capitol Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Project Managers:

  Abu-Hawash, Ahmad

• Performing Organizations:

  University of Texas, Austin

  Center for Transportation Research, 3208 Red River Street
  Austin, TX  United States  78705
• Principal Investigators:

  Helwig, Todd

• Start Date: 20170601
• Expected Completion Date: 20220630
• Actual Completion Date: 20220630
• Source Data: RiP Project 40828

Subject/Index Terms

• TRT Terms: Bridge design; Frames; Girder bridges; Load and resistance factor design; Steel bridges; Stiffness
• Subject Areas: Bridges and other structures; Design; Highways;

Filing Info

• Accession Number: 01598973
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 12-113
• Files: TRB, RIP
• Created Date: May 11 2016 2:48PM