Redundancy of prestressed concrete I-beam bridges

The AASHTO LRFD Bridge Design Specifications introduce load modifier factors in the design check equation as a means to include bridge redundancy during the design and evaluation of bridges. Preliminary load modifier tables are given in the 1994 edition pending further calibration The calibration of such factors must be based on a thorough review of the performance of typical bridge configurations. As a first step in the calibration process, this paper analyzes the redundancy of typical prestressed concrete I-beam bridge superstructures under the effect of heavy truck loads. The results of this study could subsequently be used as the basis for the calibration of rational load modifier factors that would properly account for bridge system safety and redundancy.