Finite-Element-Based Study on Girder Behavior and Load-Sharing of Shear-Connected Multigirder Prestressed Concrete Bridges

This paper aimed to study the girder behavior and load sharing of multigirder prestressed concrete (PC) bridges using an efficient nonlinear analysis tool based on finite-element (FE) modeling. A newly developed nonlinear beam element, which considers flexure–shear coupling, was adopted to model each girder. Nonlinear macroelements were adopted to model the shear connectors between adjacent girders. Nonlinear beam element modeling was validated by the experimental tests from one interior girder of the bridge considered in this study. The load–deformation relationship for the macroelement was obtained from a three-dimensional continuum-based FE model of shear connectors. The nonlinear analysis apparatus for multigirder bridge systems was applied to study the girder behavior and load sharing of the studied bridge under both flexure-dominant and shear-critical loading scenarios. The advantage of the nonlinear analysis tool, using a nonlinear beam element that considers flexure–shear coupling, was demonstrated through comparison to the model using the conventional nonlinear beam element that neglects shear deformation or flexure–shear coupling. Moreover, the influence of shear connectors on load-carrying capacity and load sharing was quantified by comparing the bridge system behavior of shear-connected girders and that of disconnected girders (with isolated individual girders). It is found that shear connectors play a significant role, but less under shear-critical scenarios than under flexure-dominated scenarios. The influence of losing shear connectors (e.g., due to corrosion damage) and increasing shear connectors on the bridge system behavior (e.g., during rehabilitation or upgrading) was studied. The results indicated that one single shear connector loss out of five between two adjacent girders could result in an overall load-carrying capacity loss of up to 14.32% for the considered multigirder bridge while adding more shear connectors between adjacent girders (e.g., from 5 to 9) can effectively improve the overall load-carrying capacity.