Structural performance of cross-laminated timber-concrete composite floors with inclined self-tapping screws bearing unidirectional tension-shear loads

This study investigated the structural performance of cross-laminated timber (CLT)-concrete composite floor with inclined self-tapping screws bearing unidirectional tension-shear loads. Five groups of push-out tests were conducted to evaluate the shear behavior of the inclined screw connector. The results showed the embedded depth of the inclined screw in the CLT had a significant influence on the shear performance of the connectors, and the vertical screws demonstrated enhanced ductility. Next, six groups of specimens were subjected to four-point bending tests to study their flexural behavior under various parameters. A screw spacing that was too small led to premature failure, whereas an increased section height greatly improved the bending performance of these specimens. One specimen in particular exhibited a plate-end shear enhancement accompanied by excellent performance in terms of flexural stiffness and bearing capacity. Furthermore, a computational optimization method for determining an effective bending stiffness of the composite floor was proposed based on ‘γ-method’. This approach expanded the application scope of traditional methods, and the calculated values were in good agreement with the experimental values. Finally, a simplified finite element model was established, and parametric finite element analysis verified that improving the shear efficiency of the connector could bring economic benefits.