地震动主方向研究及其对结构动力反应的影响

The directivity of ground motion and its effect on structural response are studied.The coordinate transformation of horizontal seismic motion in E-W and N-S directions obtained from any station is carried out with coordinate transformation of 0° to 90°, the new acceleration time history in x', y' directions under any group of θ' angles are peak acceleration values of the original time histories at each time point, and the three-dimensional seismic time-history diagram and three-dimensional response spectrum map of horizontal variation along each angle θ are drawn.The main direction of ground motion time-history θ_tmax and the main direction of response spectra θ_spmax are defined.In order to verify the influence of different earthquake directions on the structure, this paper takes Lushan middle school gymnasium which was seriously damaged in Lushan earthquake as the object, and establishes a three-dimensional spatial model of Lushan middle school gymnasium.The seismic time histories obtained from several stations near the gymnasium of Lushan middle school in Lushan earthquake are used to transform the original ground motion time histories of each station according to θ = 0° to 90° and input them into the structure respectively to get the different failure modes of the structure.The results show that the directionality of ground motion has great influence on the structure.