Out-of-plane bending behavior of cross-laminated timber members enhanced with fiber-reinforced polymers

Abstract

Carbon or basalt fiber-reinforced polymer (FRP) fabrics were bonded to the bottom of three-layer hemlock cross-laminated timber (CLT), aimed at improving its bending performance under out-of-plane loading. The FRP layer effectively enhanced bending strength by up to 23.8% and global bending stiffness with infinite shear stiffness by up to 18.4%. Carbon FRP was stronger and most effective, and combining it with an inner layer of cheaper basalt FRP also effectively reduced cost. Failure was not observed in the FRP layer, while failure at the transverse layer became more significant. Reinforcement of the transverse layer is therefore recommended to better realize the FRP enhancement effect. A predictive model for bearing capacity in bending for CLT with FRP fabric was developed and validated. Predicted bending stiffness results considering the offset of the neutral axis showed a good agreement with experimental results. The results support the application of FRP fabrics for improved bending performance for CLT panels under out-of-plane loading.