Experimental and Analytical Lateral Performance of Posttensioned CLT Shear Walls and Conventional CLT Shear Walls

Abstract

Cross-laminated timber (CLT) is suitable for shear walls owing to its high in-plane stiffness. However, according to a series of shaking table tests on multistory CLT structures, premature connection damage always occurs in CLT shear walls under the applied loading scenarios representing moderate and major earthquakes. To mitigate the premature connection damage and improve the seismic resilience of CLT shear walls, a specific kind of posttensioned (PT) CLT shear wall is proposed herein, which is constructed by posttensioning CLT wall panels to the foundation with PT steel strands or bars. Previous studies on PT CLT shear walls with vertically continuous wall panels already exist. In this study, cyclic loading tests were conducted on three PT CLT shear wall specimens with different initial posttensioning forces. Floor diaphragms were included in these wall specimens and were structurally designed to mitigate the creep deformation of the CLT floor diaphragm subjected to perpendicular-to-grain compression. In addition, two conventional CLT shear walls with wall panels connected to the foundation using metal connections were also tested. The hysteretic behavior of the PT CLT shear walls was analyzed, and their lateral load–resisting performance was compared with that of the conventional CLT shear walls. Finally, fiber-based nonlinear finite-element models were developed within the Open System for Earthquake Engineering Simulation (OpenSees) framework to duplicate the lateral performance of PT CLT shear walls and conventional CLT shear walls. Results indicate that PT CLT shear walls exhibit excellent lateral performance with self-centering capability. After the entire loading process, almost no damage occurred in the PT CLT shear walls compared with the premature damage occurring in the metal connections of the conventional CLT shear walls. A friction coefficient of 0.32 is recommended for the contact interface between the CLT and steel foundation. Furthermore, for the PT CLT shear walls or conventional CLT shear walls, their analytical responses from numerical models agree well with the experimental responses, indicating the potential values of these fiber-based nonlinear models for engineering design.