2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Mr. Kevin Tarrant, Gradient Wind Engineering Inc. (Presenter)
Mr. Liam Dupelle, Gradient Wind Engineering Inc.
Mr. Justin Ferraro, Gradient Wind Engineering Inc.
Due to the importance of wind loading on tall building design, implementation of Performance-Based Design (PBD) approach has been attempted in wind design following the success of PBD in seismic design. In previous studies, the authors have addressed basic issues in implementing PBD for tall-building wind design in terms of i) the differences in probabilistic distribution of winds versus ground accelerations, ii) singular aerodynamic effects such as vortex-shedding, and iii) the substantially longer duration of wind loading compared to that of earthquake loading. Despite these issues, there are potential cost-saving benefits of performance-based wind design (PBWD) by introducing damping associated with the hysteretic behavior of the structural materials and by explicitly satisfying performance objectives including acceleration serviceability, building drifts and limited interruption level. Building responses and hysteretic behaviors will be investigated based on nonlinear time-domain analysis of tall buildings under across-wind and along-wind loading in consideration of stiffness and strength degradation using the Bouc-Wen hysteretic model. As a result, a dynamic wind loading model simplified for PBD of a building, which envelopes the peak dynamic hysteretic response of buildings – especially under collapse prevention level across-wind loading – will be proposed. The dynamic wind loading model will make the application of PBD to tall-building wind design more practical.
In example, in order to derive general discussions and conclusions, the study will reference a generic tall building with a square plan dimension of 30 meters (m), a building height of 300 m, and an aspect ratio (slenderness ratio) of ten (10). The building’s nonlinear hysteretic behavior under across-wind loading will be simulated for a range of return periods, covering service level, strength level and collapse-prevention level (or limited interruption level) events. Here, stiffness and strength degradation of materials will be considered for long-duration vortex-shedding wind loading based on the Bouc-Wen hysteretic model, excluding pinching effects for the simplicity of analysis. Sensitivity analysis of parameters of the Bouc-Wen hysteretic model to hysteretic behavior will be investigated. A dynamic wind loading model will be presented as a set of simple sinusoidal time histories for collapse prevention level PBD of the building.