Shear behavior of flexible-sleeve perfobond strip connectors: Experimental and analytical studies

Abstract

Flexible-sleeve perfobond strip connectors (SPBL), consisting of perfobond strip connectors (PBLs) and flexible plastic sleeves surrounding transverse rebars, are considered to be an effective and ductile solution in combining steel and concrete members together in composite structures. In order to evaluate structural performance of this type of shear connectors, push-out tests were performed on sixteen SPBL specimens with varying sleeve thicknesses and number of holes. Failure modes, load-slip curves, load-uplift displacement relationships, and strain history obtained from SPBLs tests are presented and discussed. The influences of design parameters on shear performance of SPBLs are analyzed. Experimental results indicated that the plastic sleeves surrounding transverse steel rebars effectively optimized the connector’s stiffness and ductility. As compare to conventional PBL connectors without plastic sleeves, the ductility coefficients of SPBL with a 2.0 mm- and 10.0- mm thick sleeve are increased by 77.2% and 26.1%, respectively, while the corresponding initial stiffness decreased by 27.6% and 46.9%, respectively. Results also indicated that the utilization of plastic sleeves effectively diminished the uneven effects among the multi-hole PBLs. Also, and as compared to triple-hole PBL connectors without flexible sleeves, providing a 2.0 mm- and 10.0 mm- thickness sleeves to transverse rebars decreased the uneven load coefficient by 26.3% and 89.7%, respectively. A comparison between experimental and analytical results using PBLs published formulas indicated that such existing formulas failed to address shear capacity of the multi-hole SPBLs. Accordingly, an analytical model that considers the uneven loadings and sleeve thickness effects that is capable of predicting the load-carrying capacity of multi-hole SPBLs was developed, and calibrated using experimental results.