Empirical Load-Slip Models for Shear Stud Connectors in Solid Concrete Slabs

Deformations of shear connectors at different load levels, usually described by load-slip curves, influence the distribution of shear forces in the connectors, affecting the resistance, stiffness, and ductility of steel-concrete composite members. This paper presents empirical models to predict load-slip curves of headed shear studs in solid concrete slabs. The models, which account for the stud shank diameter, concrete compressive strength, stud tensile strength, stud height-to-diameter ratio, concrete type, and the position of slab reinforcement, were developed using regression analyses of load and slip measurements from 180 tests from the literature. The accuracy of the developed models in predicting the slip, load, shear stiffness, and slip capacity was found satisfactory considering the scatter of the test measurements. Comparisons of the developed and existing models indicated that the former outperform the latter. For the full load-slip curves with the falling branch, the slip prediction accuracy for the best developed model is characterized by RMSE of 1.18 mm, R2 of 0.879, and mean and CoV of the test-to-prediction ratios of 1.02 and 0.599. In contrast, these metrics for the only existing model capable of capturing the falling branch are 1.47 mm, 0.776, 0.75, and 0.717, respectively. The effects of the shear connection parameters on the load-slip curves were evaluated and discussed. A web application was created and deployed online to generate load-slip curves from the developed models, and to determine the shear stiffness and slip capacity using various criteria based on the predicted load-slip curves. This study contributes to understanding shear stud deformations in solid concrete slabs and the parameters affecting them. The load-slip curves predicted by the developed empirical models will benefit analytical and numerical studies aimed at investigating the effects of stud deformations on the resistance, stiffness, and ductility of steel-concrete composite structures, contributing to improved design rules.