Applicability of random decrement technique in extracting aerodynamic damping of crosswind-excited tall buildings

Abstract

At the vicinity of vortex lock-in wind speed, the nonlinear aerodynamic damping effect is significant. It can greatly promote the surge of crosswind response, even threaten structural safety and serviceability of tall buildings. Techniques dependent on experimental measurement to identify aerodynamic damping have been developed for estimating crosswind response from wind loading spectrum. Random decrement technique (RDT) as one frequently mentioned technique of system identification has been used in literature to extract aerodynamic damping from stochastic crosswind response, although it was originally suitable for linear single degree of freedom system with a constant damping ratio. This study investigates the applicability of RDT in extracting aerodynamic damping of tall buildings. The models of linear and nonlinear aerodynamic damping are applied to simulate crosswind response of a square section tall building. Accordingly, the wind loading spectra based on high-frequency-force-balance (HFFB) testing and the model recommended by AIJ are utilized respectively to consider the effect of random wind load on the characteristics of crosswind response. To examine the accuracy and efficiency of RDT, aerodynamic damping is extracted through two approaches and compared with target value. Moreover, the influence of varying wind loading spectra on amplitude-dependent aerodynamic damping is demonstrated.