Behavior of stud connectors under combined shear and tension loads

In order to investigate the behavior of stud connectors subjected to combined shear and tension loads, twelve pull-out, six push-out and twelve modified push-out specimens were prepared and tested. Failure modes under different loading conditions are presented and compared. Based on the seventy-six test results in this work and those available in the literature, an improved shear-tension interaction strength equation is proposed. In addition, expressions for computing the shear stiffness reduction factor and predicting the load-slip relation under combined loading are also developed. The results indicate that both the shear deformation and necking phenomenon are observed for the steel failure mode of studs under combined loading. With an increase in applied tension force, both the shear stiffness and shear strength decrease significantly. The proposed shear stiffness reduction factor and load-slip expression can take into account the influence of tension force and peak slip, and thus give more reasonable predictions of shear stiffness and load-slip curve under shear loading and under combined loading. The proposed interaction strength equation is capable of predicting the interaction strength more accurately, when compared with other available equations in the literature, and suggests that interaction effects can be neglected when the shear or tension force is smaller than 10% of the ultimate strength under pure shear or pure tension, respectively.