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为研究实心结构古塔在地震作用下的动力反应及破坏机制,以陕西省西安市兴教寺玄奘塔为原型,设计制作了1∶8比例模型结构,进行了振动台试验。通过输入不同烈度的单向、双向及三向地震波,测试了结构楼层的位移及加速度反应,观测了结构破坏现象,分析了结构的动力特性变化规律,对比了各加载工况下结构各楼层地震反应的变化特点。结果表明,设防地震作用下塔体底部楼层首先发生水平开裂与塔身斜向开裂,随着地震烈度的提高,破坏区域随之向上延伸,结构自振频率降低,频响曲线峰值点增多;当地震烈度相同时,不同加载工况下结构的水平反应峰值相差不大,但不同地震波作用下竖向加速度反应峰值相差较大;动力放大系数随楼层高度呈“S”形分布,顶层的水平加速度反应最大,中部楼层的竖向地震反应最大。因此,古塔破坏是在水平向与竖向地震共同作用下发生的,结构的底部及中部楼层为抗震的薄弱部位。
In order to study the dynamic response and failure mechanism of an ancient pagoda with solid structure under the action of earthquake, a 1: 8 model structure was designed and prototyped by the Xuan Zang Temple of Xuan Temple in Xi’an, Shaanxi Province. Shaking table tests were carried out. By inputting unidirectional, bidirectional and three-direction seismic waves of different intensities, the displacement and acceleration responses of the structural floors were tested, the structural failure phenomena were observed, and the variation laws of the dynamic characteristics of the structures were analyzed. The seismic responses of each floor under different loading conditions Response to changes in characteristics. The results show that under the action of fortified earthquakes, horizontal cracking and tower body cracking begin to occur at the bottom of the tower. As the seismic intensity increases, the damaged area extends upwards and the natural frequency of the structure decreases and the peak points of the frequency response curve increase. When the seismic intensity is the same, the horizontal response peaks of structures under different loading conditions are similar, but the peak values of vertical acceleration response vary greatly with different seismic loads. The dynamic amplification factor is distributed in a “S” shape with the floor height, The response of horizontal acceleration is the largest, and the vertical seismic response of the middle floor is the largest. Therefore, the destruction of ancient pagodas occurred under the action of horizontal and vertical earthquakes, and the bottom and middle floors of the structure are the weak parts of earthquake resistance.