The report documenting the calibration process (NCHRP Report 368) was completed prior to the final selection of load and resistance factors used in the AASHTO LRFD Bridge Design Specifications (LRFD Specifications). The reliability analysis that serves as a basis for load and resistance factors included in the LRFD Specifications was performed for the AASHTO Standard Specifications (1989 edition). As a result, NCHRP Report 368 provides the background information and the calibration procedure for the LRFD Specifications, but it does not correspond to the actual code provisions. Therefore, there is a need for updating the calibration report so that it can serve as a reference for the specifications.
The objective of this project was to fully document the calibration of the AASHTO LRFD Bridge Design Specifications (LRFD). Reliability analyses for representative bridges, including steel (non-composite and composite girders), reinforced concrete T-beams, and prestressed concrete AASHTO type girders were performed using the LRFD load and resistance factors.
The project is complete. The project report has been distributed to the states and can be downloaded here (2,748 KB PDF). (NCHRP Staff: D. B. Beal)