Effect of flange widths of T-type PBL shear connectors on the mechanical performance in negative bending moment region of steel-concrete composite beams

There are higher requirements for shear connectors as the span length of steel-concrete composite structures increases. T-type perfobond rib (T-type PBL) shear connectors have better mechanical properties than conventional PBL, but the effects of the flange on the overall performance of composite beams have barely been well understood. Therefore, four-point bending tests were first conducted to investigate the failure mode, loaddeflection behavior, and strain distribution of steel-concrete composite beams with the T-type PBL connector under negative bending moments. Subsequently, verified finite element models were established to evaluate the effect of flange width and reinforcement ratio on the flexural performance based on the test results. Finally, a bearing capacity evaluation formula for steel-concrete composite beams in the hogging moment region was proposed considering T-type PBL connectors. Based on the test results, the failure mode of specimens under negative bending moments was bending failure along with cracking of the concrete slab and local buckling of the steel beam flange. The specimens with T-type PBL shear connectors showed better strengthening performance than those with conventional PBL. The bending bearing capacity of composite beams with flange widths of 70 mm, 100 mm, and 130 mm were 6 %, 17 %, and 22 % higher than those with conventional PBL connectors, respectively. The FE parametric study showed that the bearing capacity of the composite beam was improved with the increase of flange width and reinforcement ratio. The flange width and reinforcement ratio of 70 mm and 1 % were recommended, respectively. The evaluation formula was verified by the test and FE results, with an average calculated-to-FE result ratio of 0.99 and a standard deviation of 0.17. This study could enhance the understanding of the behavior of steel-concrete composite beams with T-type PBL connectors in the negative bending moment region and promote the application in long-span composite constructions.