Robustness evaluation on galloping stability of bridge local structure

Galloping is a self-excited divergence vibration, which would cause serious damage to the local structure of the bridge. In order to evaluate the galloping stability under extreme wind loads, a robustness index β is proposed. Firstly, the extreme reference wind speeds U_b of long return periods are selected to reflect the extreme wind conditions. Then through the improved equivalent checking point method, β could be obtained by solving the security domain function Z_b , which is constructed with four galloping-related random variables. An assistant arch rib has been taken as an example to analyze its robustness. The results show that when the return period of U_b reaches 10280 years, its robustness index can still meet the requirement of failure probability less than 1%. Besides, assuming that basic galloping critical wind speed U_g obeys the normal distribution is conservative, since its robustness index is smaller than those obeying other distributions.