Structural performance of slabs in composite box girder considering compressive membrane action

Abstract

In steel-concrete composite box girders, the concrete slabs are laterally and rotationally restrained by diaphragms, surrounding slabs, and the steel box girder through shear connectors, thus developing compressive membrane action under vertical loading. However, the compressive membrane action in composite box girder bridge decks has rarely been considered, despite its significant effect on the structural performance of the slab. In this study, transverse behavior of slabs in composite box girder considering compressive membrane action was investigated and a new calculation method for assessing the load capacity of slabs with different boundary conditions was proposed. Static loading tests on six composite box girder deck slabs were first carried out. Elaborate finite element models were established and further validated by test results. Furthermore, the load capacities of the slabs were compared between the test results and several traditional theoretical predictions. It is indicated that the compressive membrane action significantly enhanced the load capacities of deck slabs. Moreover, this study reveals that ignoring the effects of rotational restraint stiffness and lateral restraint location on the compressive membrane action may lead to significant error. Based on the test results and the numerical parametric study, a new calculation method for the load capacity of laterally and rotationally restrained slabs was proposed. Comparisons with both the numerical and experimental results demonstrated that the proposed method can provide accurate and reliable predictions.