Impact of AASHTO LRFD Specifications On Design Of Prestressed Concrete Bridge Girders

This paper summarizes the results of a study conducted to evaluate the impact of the AASHTO LRFD Bridge Design Specifications (3rd edition) on the design of prestressed concrete bridge girders as compared to the AASHTO Standard Specifications for Highway Bridges (17th edition). The portion of the study reported in this paper is limited to single span Type C and AASHTO Type IV bridge girders. The impact of the LRFD Specifications was evaluated for the flexural service, flexural strength, and shear strength limit states. When comparing the two specifications, differences were observed in the live load moments and shears, distribution factors, prestress losses, and flexural strength estimates. However, major differences were observed in the design requirements for transverse and interface shear. The impact of new interface shear provisions currently being considered for inclusion in the LRFD Specifications was assessed. The findings of this study provide information on how design parameters are affected by the transition to the LRFD Specifications.