Numerical Studies on the Performance Degradation of Headed Stud Shear Connectors in Composite Structures Under Freeze-Thaw Cycles

This study investigated the performance degradation of headed stud shear connectors in composite structures subjected to freeze-thaw cycles (FTCs). Parametric finite-element (FE) analysis was conducted, incorporating damage plasticity models to assess the failure progression of these shear connectors while considering concrete strength, stud dimensions, and FTC number. The parameters under scrutiny have concrete compressive strengths of 30/40/50/60 MPa, stud diameters of 13/16/19/22/25 mm, stud height-diameter ratios of 4/5/6, and FTC numbers of 0/50/100/150. A comprehensive parametric study was carried out to investigate the shear behavior of stud connectors under varying FTC conditions and identify the critical factors affecting their shear resistance. Results demonstrate that, in comparison to experimental findings, the ultimate shear strength obtained through numerical analysis falls within a margin of +/- 10%, and the secant shear stiffness remains within +/- 15%. Notably, FTCs exert a pronounced influence on ultimate shear strength and shear stiffness, with both parameters experiencing nearly a 20% reduction after 150 FTCs. Based on regression analysis of FE results, a new equation was proposed to determine the ultimate shear strength of headed stud shear connectors, incorporating four parameters: stud diameter, stud height, concrete compressive strength, and FTC number.