Shear performance of PBL shear connectors under combined bending-shear loading: Experimental and numerical studies

To better understand the shear performance of PBL shear connectors in negative moment regions, modified push-out tests were conducted to investigate their behavior under combined bending-shear loading. The effects of the pre-tightening force, steel plate arrangement, perforated reinforcement diameter, and hole diameter on shear performance were analyzed thoroughly. The results showed that pre-tightening force exhibited a non-monotonic effect: increasing the force from 0 to 20 kN raised shear capacity by 22 %, but further increasing to 30 kN led to a 9 % reduction due to concrete damage. Upon increasing the perforated reinforcement diameter from 12 mm to 20 mm, the shear stiffness improved significantly by 52 %, whereas the shear capacity increased by only 12 %. Due to frictional enhancement, specimens with normal arrangement showed at least 20 % higher shear capacity compared to those with none-friction arrangement. Additionally, increasing the hole diameter can effectively enhance structural ductility, but it demonstrates the weakest improvement in shear capacity. Based on the true stress-strain curve, finite element models were developed and validated. Parametric analysis revealed that increasing the perforated plate thickness significantly enhanced shear capacity with improvements no less than 9 %, whereas plate height showed weaker influence on shear performance compared to thickness. Increasing the hole number markedly enhanced shear capacity. These findings could provide critical insights for optimizing PBL shear connector design in negative moment regions of steel-concrete composite structures.