Experimental and analytical studies on interfacial shear behavior of socket connections with shear keys

Socket connections with shear key interfaces have been widely used in precast building and bridge construction, of which the interfacial shear capacities become the main concern. Despite various previous studies, the force transfer mechanisms of shear key joints in socket connections have not been investigated thoroughly. In this paper, push-off tests were carried out on 16 specimens to investigate the interfacial shear behavior of such joints. Four failure modes were observed: post-pour concrete failure, shear key failure, splitting failure, and slip failure, among which splitting failure and slip failure should be avoided. Results showed that enhancing lateral constraint and post-pour strength, while reducing gap widths, significantly increased the shear capacity. Among different shear key configurations, the performance of joints with multiple small shear keys was the most satisfactory. According to the test results, the mechanical model for shear key joints in socket connections was proposed based on strut and shear friction theory. Distinct from previous models, the proposed model could cater to joints with moderate gap widths and constrained lateral dilatation, guiding the design of socket connections. Several design recommendations regarding the shear key dimensions, post-pour materials, and socket foundation configurations were proposed for engineering reference.