Numerical Simulation and Parametric Analysis of Posttensioned C-Shaped CLT Shear Walls

Abstract

Posttensioned (PT) cross-laminated timber (CLT) shear wall systems provide a low-damage seismic solution for mid-rise and high-rise timber structures in high seismic regions. Experimental testing of 8.6-m-tall PT-CLT shear walls with three different configurations—single wall (SW), double wall (DW), and C-shaped core wall (CW)—demonstrated that effective coupling actions could be achieved in double and C-shaped walls using strong and stiff vertical in-plane and orthogonal joints. This paper extends the experimental study through numerical simulation in a three-dimensional domain to perform parametric analyses and assess a prototype 6-story PT-CLT CW system. A model unit of a SW was developed and then assembled to construct models for DW and CW in a 3D domain. Validation of the model was carried out against the test data. The developed model offered reasonable predictions for wall strength, stiffness, tendon force variation, slip at in-plane joints, and accumulated energy dissipation. The model limitations included its inability to account for out-of-plane motions for SW and its tendency to underestimate slip at orthogonal joints, with errors not exceeding 20%. A further parametric analysis investigated the effect of altering the spacing of in-plane and orthogonal joints on composite action (CA) values, strength, stiffness, and hysteretic damping of CW systems. Results revealed a consistent impact of fastener spacing on CW system properties, regardless of using 90° or mixed-angle screws. Decreasing spacing improved lateral resistance but could reduce energy dissipation capacity. In particular, in-plane joint spacing had a more pronounced effect on the CW performance than orthogonal joints. The model was employed to assess the seismic performance of a 6-story PT-CLT CW composed of two C-shaped walls. Through monotonic and cyclic pushover analyses, alongside capacity spectrum method utilization, the study demonstrated the viability of PT-CLT CWs in design scenarios. The model exhibited the potential for analyzing PT-CLT CWs with different configurations within a 3D domain.