A comparative study of live load distribution in Skewed Integral and Simply Supported Bridges

In this study, the effects of skew and superstructure-abutment continuity on the distribution of live load effects among the girders of Skewed Integral Abutment Bridges (SIBs) and Skewed Simply Supported Bridges (SSBs) is investigated comparatively. For this purpose, numerous 3-D and corresponding 2-D finite element models of several single span SIBs and SSBs are built. Analyses of the models are then conducted under AASHTO live load. In the analyses, the effect of various skew angles and superstructure properties such as girder size and spacing, number of girders, span length as well as slab thickness are considered. The results from the analyses are then used to calculate the Live Load Distribution Factors (LLDFs) for the girders of SIBs and SSBs as a function of skew and the above-mentioned structural parameters. LLDFs and Skew Correction Factors (SCFs) are also obtained from AASHTO equations developed for SSBs. These LLDFs and SCFs are compared with those calculated from the analyses in order to assess the applicability of AASHTO equations to SIBs. The results revealed that live load distribution of moment and shear among the girders is improved in SIBs compared to SSBs. Increase in skew generally decreases the live load effects among the girders of SIBs.