State augmentation method for buffeting responses of wind-sensitive structures in wind environments with large turbulence intensity

Abstract

Recent studies have shown that wind fields with large turbulence intensity are frequently observed in non-synoptic winds such as typhoons and hurricanes. The quadratic terms of the fluctuating wind speed are important for calculating buffeting responses of wind-sensitive structures under high turbulence. In this study, a moment-based method, which is called the state augmentation method, is used to obtain high-order response moments and avoid the large computational cost of the high-order frequency domain method. First, the buffeting force formula with nonlinear velocity terms is established, and the Non-Gaussian buffeting force is further approximated as a polynomial of the Ornstein–Uhlenbeck (OU) process. Then, an augmented state vector is introduced to express the relationship between the statistical moments of each order, and the 1st to 4th response moments can be solved sequentially by a particular set of linear equations. Finally, the extreme responses of a single-degree-of-freedom (SDOF) tower and a long-span suspension bridge are calculated as engineering examples. By comparing the computation results with the frequency method, it is proven that this moment-based method has a sufficient accuracy in analysing quadratic terms. The calculation results also show that quadratic terms under high turbulence significantly amplify the non-Gaussian peak factor and extreme responses.