Abstract:

Objective: The lateral performance of cross-laminated timber (CLT) shear wall made of domestic fast-growing poplar wood （Populus spp.） was investigated under cyclic load. The effects of wood thermal pretreatment and wall accelerated weathering on the lateral performance of CLT shear wall were determined. The results might serve as a valuable reference for thermal modification and effective use of low-value fast-growing wood in buildings. Method: The CLT wall made of fast-growing poplar wood was taken as the research object, and its lateral performance was compared to that of commonly-used spruce (Picea abies) CLT wall in timber structures. According to previous studies, poplar wood was thermally treated at 180 ℃, and a total of five full-scaled CLT shear walls were prepared and tested in this study. The lateral performance tests of CLT shear walls with the absence and presence of accelerated weathering were performed under cyclic load. Result: The peak load, elastic lateral stiffness, and energy dissipation of the untreated poplar CLT shear wall under cyclic load decreased by 5.8%, 12.9% and 8.0%, respectively, as compared to those of spruce CLT shear wall with the same laminate strength class. The characteristics of lateral performance of poplar CLT shear walls reduced to varied degrees, after thermal pretreatment of wood, accelerated weathering treatment of walls, or a combination of the two treatments. Compared with the untreated poplar CLT walls, the ultimate bearing capacity, elastic lateral stiffness, and energy-consuming capacity of the CLT shear wall, after accelerated wall weathering treatment, reduced by 9.4%, 9.7%, and 11.2%, respectively; and the wood was treated with high temperature. After accelerated weathering, the ultimate bearing capacity, elastic lateral stiffness, and energy consumption capacity of the CLT shear wall changed less, decreasing by 2.9%, 2.4%, and 5.0%, respectively. Conclusion: The lateral performance of the fast-growing poplar CLT shear wall under cyclic load was slightly lower than that of the spruce CLT shear wall with the same laminate strength class. The poplar CLT shear wall failed in a manner similar to the spruce wall. The damage to spruce and poplar CLT walls under lateral load conditions was mostly caused by screw breakage. The failure mode of poplar CLT shear wall made of thermally-treated poplar was wood fracture or split at the connection, which was identical to the failure mode of the accelerated weathering CLT wall and accelerated weathering wall manufactured using heated wood. Thermal pretreatment of wood can reduce the influence of accelerated weathering on the lateral performance of shear walls, resulting in comparatively strong resilience to wall degradation. The theoretical lateral peak load of CLT shear walls was established, and the error between the theoretical and test value was less than 10%.

Key words: fast-growing poplar wood, cross-laminated timber shear wall, lateral performance, thermal pretreatment, accelerated weathering