Cross-laminated timber (CLT) possesses both good shape stability and possible two-way force transfer ability due to its crosswise lamination. However, the transverse layers in CLT are prone to rolling shear failure under an out-of-plane load. An innovative multi-layer composite laminated panel (CLP) was developed by combining structural composite lumber (SCL) and dimension lumber to overcome the rolling shear failure while maintaining the high mechanical performance and aesthetic appearance of natural wood. The mechanical properties of 5-layer CLP that consisted of laminated strand lumber (LSL) and dimension lumber with different layups were evaluated by both static and modal tests. The results showed that the shear resistance, bending stiffness, and moment resistance of CLP were up to 143%, 43%, and 87% higher than their counterparts of regular CLT, respectively. The failure modes observed in both shear and bending tests indicated that the use of LSL in transverse layers could eliminate the potential rolling shear failure in CLT. With the lamination properties from components tests as inputs, the validity of shear analogy method was assessed by test results. The mechanical properties can be well predicted by shear analogy method except for the bending moment resistance of CLP and CLT with either rolling failure in the cross layer or tension failure in the bottom layer.

Mass timber panel (MTP)-concrete composite floors are gaining increasing interest from builders and designers due to their optimized structural performance, light self-weight, and aesthetically exposed wood ceilings. Among various connecting techniques between timber and concrete, notched connections made by cutting grooves on timber and filling them with concrete are considered as one of the most structurally efficient and cost-saving connecting solutions. Numerous ways of making and reinforcing the notched connections, however, hinder the standardization and development of the design guidelines for this type of connection, which reduces the competitiveness of MTP-concrete composite floors. In this study, experiments were carried out to investigate the performance of MTP-concrete composite floors with different connection designs. Nine composite floor specimens with varying span, connection number, notch depth, concrete thickness, and loading direction were designed and tested under bending. The bending stiffness, load-carrying capacity, ductility, and failure mode of tested specimens were studied and discussed. Test results show that the connection number, notch depth, and concrete thickness affect the bending stiffness and strength of the floor positively, an increase in floor span impacts the floor performance negatively, whereas the effect of a limited number of self-tapping screws in the notch is negligible. The study also shows that MTP-concrete composite floors with high strength, high stiffness, and good ductility can be achieved through the optimized design of notched connections.