Extreme value of typhoon-induced non-stationary buffeting response of long-span bridges

This paper concerns the extreme value of typhoon-induced non-stationary buffeting response of long-span bridges. The framework of non-stationary buffeting analysis is briefly introduced first, in which the non-stationary buffeting response is regarded as the summation of a time-varying mean response and a dynamic response that can be represented by a zero-mean evolutionary Gaussian process characterized by an evolutionary power spectral density (EPSD) function. The formulas for determining approximate probabilistic characteristics of extreme non-stationary responses are then derived by extending the currently-used Poisson and Vanmarcke approximations. By comparing with the Monte Carlo solution, the extended approximations for extreme value of non-stationary responses are found reliable and accurate enough. Particularly, the extended Vanmarcke approximation can give closer results to the Monte Carlo solution than the extended Poisson approximation. The extended Vanmarcke approximation is finally applied to the Stonecutters Bridge to find the extreme value of non-stationary buffeting response of the bridge to a strong typhoon. The results show that the extreme displacement responses of the bridge from the non-stationary buffeting analysis are larger than those predicted by the conventional stationary buffeting analysis, and therefore the non-stationary buffeting analysis is necessary.