The extent of high-temperatures on the interfacial shear strength of CFRP-strengthened shear keys: NLFEA and theoretical calculation

This study examines the behavior of shear keys under the combined effect of CFRP strengthening and temperature values. The interfacial shear strength behavior was captured using the three-dimensional nonlinear finite element analysis (NLFEA) technique with a newly proposed theoretical model. The simulated models were verified using experimental push-off tests published in the literature. This is followed by expanding the validated specimens to examine the effect of the high temperatures (20, 250, 500, and 750 oC), the number of CFRP strips provided at the interface connection (1, 2, 3, a, 5, and 6), and the number of internal steel stirrups (0, 1, 2, 3, 4, and 5). Results revealed that reinforcing the shear keys with CFRP strips reduces the propagated crack widths and the associated slip compared to the control one. This proves the proposed CFRP strengthening configuration's role and effectiveness in enhancing the structural performance of the interfacial shear strength. In addition, it has been shown that the exposure temperature's value directly affects the longitudinal shear strength, failure mode, slippage, and toughness.