Effect of Skew on Shear Loads in Multi-Cell Box Girder Bridges

Multi-cell box girder bridges are the most common type in Caltrans' bridge inventory. Caltrans has adopted the AASHTO LRFD Bridge Design Specifications for the design of these bridges. However, the skew factors for multi-cell box girder bridges are based on a grillage model, which does not capture torsional effects correctly. Further, the AASHTO factors are intended for live load distribution only, and their applicability to permanent loads is unclear. Caltrans has directed the designers to use the more conservative factors in Caltrans' Bridge Design Aids. The skew factors currently in use were developed over 30 years ago, based on simple-span bridges with a limited range of plan geometries. These factors could result in over-design of multi-span bridges. This conservatism coupled with the new truck (HL93 and P15) design loads and improved estimates of prestress losses has led to significant increases in construction costs.

Language

• English

Project

• Status: Active
• Sponsor Organizations:

  California Department of Transportation

  1227 O Street
  Sacramento, CA  United States  95843
• Project Managers:

  Sikorsky, Charles

• Principal Investigators:

  Tuan, Christopher

• Start Date: 20080701
• Expected Completion Date: 0
• Actual Completion Date: 20110630
• Source Data: RiP Project 27727

Subject/Index Terms

• TRT Terms: Box girder bridges; Bridge design; Bridges; Inventory; Load and resistance factor design; Skew bridges
• Uncontrolled Terms: Multispan bridges
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 01466057
• Record Type: Research project
• Source Agency: California Department of Transportation
• Files: RIP, STATEDOT
• Created Date: Jan 3 2013 3:10PM