EFFECT OF CONNECTION NONLINEARITY ON WIND PERFORMANCE OF TALL MASS TIMBER BUILDINGS

Mass timber products have gained significant recognition in the construction of tall buildings, providing a sustainable solution for urban development. As those products have shown high in-plane strength and stiffness, energy dissipation and ductility of lightweight and flexible tall mass timber structures under lateral loads rely on metal connectors (e.g., hold-downs, shear brackets, and spline joints). Those connectors are commonly modeled as nonlinear springs in conventional seismic analysis but are often simplified as linear in serviceability wind assessment. However, under extreme wind hazards, excessive wind-induced vibrations may cause these connections to enter the nonlinear stage. This paper aims to investigate the impact of nonlinear connections on the wind performance of tall mass timber buildings. To improve the efficiency of traditional discrete connectors modeling in cross-laminated timber (CLT) wall panels, a novel “nonlinear connection zone” modeling approach is proposed to integrate all connectors into a continuous shell strip. The modelling method is first calibrated and validated with full-scale CLT shear wall tests with both single-panel and double-panel configurations. Next, the method is applied to a 30-story mass timber building using numerical fluid-structure interaction technology at extreme wind intensity. The analysis results showed that the case-study building exhibited nonlinear behavior at the design wind speed with a return period of 1,000 years, and neglecting nonlinearity would underestimate the peak response.