Bi-directional wind-induced vibration control of high-rise buildings using bi-directional rail variable friction pendulum-tuned mass damper

Abstract

Flexible high-rise buildings are extremely vulnerable to wind, especially when synchronously subjected to alongwind and crosswind forces. In this scenario, acceleration-sensitive targets (such as delicate instruments) are at risk of damage. Moreover, occupant comfort and structural safety may be degraded due to excessive bi-directional vibrations. To resolve this problem, a bi-directional rail variable friction pendulum-tuned mass damper (BRVFP-TMD) is used to achieve optimal bi-directional wind-induced vibration control. The modeling of the BRVFP-TMD for bi-directional high-rise buildings under bi-directional winds was performed. Further, the physical interaction forces of the BRVFP-TMD with a multi-degree-of-freedom structure and the governing equations for the modal structure with the BRVFP-TMD were derived, with experimental results confirming the effectiveness of the linear variable friction force. For the BRVFP-TMD with a lightly damped structure, acceleration optimizations were conducted to obtain closed-form solutions for optimal parameters. However, the deployment position of the tuned mass damper (TMD) was found to degrade the optimal control performance significantly. Therefore, for the convenience of engineers, improved optimal solutions were obtained by considering the actual deployment position of the TMD and the influence of inherent structural damping. The stochastic linearization method was used to evaluate the effect of linear hysteretic damping (HD) with equivalent viscous damping (VD) in the field of random theory. Accordingly, a closed-form expression for the VD ratio was proposed to represent HD. Numerical verifications of a Chinese landmark (Canton Tower) subjected to bi-directional winds were assessed through time history and frequency decomposition analyses. The results verified the effectiveness, correctness, and necessity of the BRVFP-TMD; the improved optimal solutions were also confirmed. Compared with the closed-form solution, which neglects the deployment position of the TMD, and the classic TMD, the improved optimal solutions of the BRVFP-TMD demonstrated superior performance in mitigating both structural displacement and acceleration. The vibration reduction ratios achieved were 44.55% for the displacement at the top of the mast and 46.69% for the acceleration at the top of the main tower.