Envelope Random Decrement Technique for Identification of Nonlinear Damping of Tall Buildings

To accurately identify the nonlinear damping ratio of tall buildings, the authors propose an envelope random decrement technique (RDT). To verify the accuracy of the envelope RDT for the evaluation of amplitude-dependent nonlinear damping ratio, an iterative computing method, which can accurately work out the response of structures whose parameters depend on the response amplitude in any form, is also proposed. Then, using three different damping models in the numerical simulations, of which the response is calculated by the proposed iterative computing method, the applicabilities of traditional RDT, RDT ranked by peak amplitude, and the envelope RDT presented in this paper for the evaluation of amplitude-dependent nonlinear damping ratio are analyzed and compared. Results indicate that envelope RDT is better than the other two methods for the evaluation of amplitude-dependent nonlinear damping ratio. Finally, the envelope RDT is applied to identify the damping ratios of the Shanghai World Financial Center.