Simulation of non-stationary wind velocity field on bridges based on Taylor series

Abstract

The simulation of non-stationary wind velocity field based on the spectral representation method often requires significant computational efforts due to the summation of trigonometric functions usually involved in the simulation procedure. Some techniques which make use of FFT algorithm have been developed but most of these techniques deal with seismic ground motions. Limited effort has been devoted to the simulation of non-stationary wind velocity. Therefore, in this paper, a spectral-representation-based technique which takes advantage of FFT algorithm is proposed by combining Cholesky decomposition and Taylor series expansion. The approach consists of locating and expanding the time and frequency non separable part of the decomposed evolutionary power spectral density function by mean of Taylor series expansion to allow the application of the FFT algorithm. Samples of non-stationary wind velocity can be then generated through multiple executions of the FFT algorithm once the Taylor series expansion is successful. The present approach, which is primarily developed for the simulation of non-stationary wind velocity on long-span cable supported bridges, is very efficient since the summation of the trigonometric functions can be carried out through FFT algorithm which is well known for its higher efficiency. The approach was further improved by reformulating the simulation formulas where the order in which the summation operations are executed is imposed.