Experimental and nonlinear-analytical studies of cross-laminated-timber concrete composite floors with interface shear resistance enhancement of plate-end

Cross-laminated-timber (CLT)-concrete composite system has drawn more attention as a new technology. This study investigated CLT-concrete composite (CCC) floor with shear resistance enhancement of plate-end experimentally and analytically. In order to obtain the shear performance of coach screw connectors, two groups of push-out tests were carried out. Based on the test results and failure modes, three characteristic slip moduli of the push-out specimen were calculated. Then, three groups of four-point bending tests were conducted to study the flexural behavior of CCC floor with different screw arrangements. One group of bending specimens was designed by shear resistance enhancement of plate-end and showed excellent performance in terms of bending stiffness and bearing capacity. Furthermore, the nonlinear analytical model for calculating the relative slip of composite floor was established, which took into account the stiffness reduction effect of the connectors. Finally, based on the generalized connection system model, the optimized γ-method for calculating effective bending stiffness was proposed, which considered the Interface slip modulus transformation. By comparing with the experiment results, the analytical methods presented in this study could predict interface relative slip and effective bending stiffness of composite floor well, which provided important references for the design of CCC floor.