Early age behavior of clustered shearing connector pocket in bridge composite girder

Abstract

Early age behavior of shearing connectors is of great significance for the performance of composite structures. To improve the structural mechanical state and reduce the risk of shrinkage cracks, the non-shrinkage concrete and the clustered shearing connector pocket are used in engineering applications, but the existing empirical model can hardly describe the physicochemical process in the actual structure. Focusing onresponsestiphysics mechanism of concrete shrinkage and the contribution of expansion additive, a comprehensive model is proposed for non-shrinkage concrete in this paper, and the processes of the hydration reaction, the humidity transport, and the mechanical response are included. The free shrinkage test regresses the parameter of material shrinkage, and the corresponding structural test verifies the multiphysics model of the clustered shearing connector pocket. With the volume increasing along the hydration reaction of expansion additives, the −120 με shrinkage of normal concrete is compensated to the 160 με expansion. In the clustered shearing connector pocket, the slight expansion of non-shrinkage concrete can keep the structural compression state and eliminate the risk of local cracks. According to structural test, the early age behavior is constrained by the prefabricated deck, reinforcement and clustered studs greatly, and the expansion strains at the pocket upper and bottom are reduced by about 16% and 72%, respectively. In the multiphysics simulation, not only the time-dependent shrinkage strains at different positions are predicted accurately, but also the detailed distributions of hydration ratio, relative humidity and mechanical stress are also presented. Eventually, the numerical comparison discusses the improvement of non-shrinkage concrete, the influence of relative humidity in the curing environment and the design modification of stud layout, and the peak stress in stud bodies can be reduced by about 18.42%, which is significant and practical for improving related construction.