Dynamic Response of Tall Mass-Timber Buildings to Wind Excitation

Abstract

The use of timber panels to construct the lateral and gravity load resisting systems of tall mass-timber buildings makes them lightweight and less stiff than buildings made from conventional construction materials. As a result, frequent exposure to wind-induced oscillations could cause discomfort to the occupants. This study examines the dynamic response and serviceability-performance of five case study tall mass-timber buildings varying in height (10-, 15-, 20-, 30-, and 40-story). In the assessment, the case study buildings are structurally designed according to the 2015 National Building Code of Canada and CSA O86-14 standard. High-frequency pressure integration wind tunnel tests are conducted to obtain floor-by-floor aerodynamic wind load time histories. Dynamic structural analyses in the frequency domain are performed to calculate the peak floor accelerations for various levels of critical damping ratios, wind directions, and exposure conditions. For validation and to include the possible motion-dependent effects, such as aerodynamic damping, aeroelastic wind tunnel tests are also carried out on the model of the 40-story tall mass-timber building. A base-pivoted two-degrees-of-freedom stick type aeroelastic model is designed and built to simulate the dynamic response of the prototype building in its two fundamental sway modes of vibration. Overall, it is shown that the dynamic response of tall mass-timber buildings under wind excitation is strongly dependent on the height, structural damping, local turbulence intensity, and wind direction. Based on the case studies, recommendations regarding the habitability of mass-timber buildings, critical height limit, and mitigation strategies for wind-induced excessive motions are forwarded.