随机地震激励下高台基木结构古建筑的响应分析

ANALYSIS OF RESPONSE OF ANCIENT TIMBER BUILDINGS ON THE HIGH PEDESTAL UNDER RANDOM EARTHQUAKE EXCITATIONS

为了研究高台基木结构古建筑的随机地震响应特征,以西安鼓楼为例,分别建立了鼓楼下部高台基、上部木结构和整体结构的有限元模型。选择合理的地震动模型,采用绝对位移直接求解的虚拟激励法,利用ANSYS有限元软件的谐响应分析模块对鼓楼进行了随机地震响应分析,分别得到了鼓楼通柱有关节点的位移和加速度功率谱。结果表明:在随机地震激励下,结构位移和加速度功率谱峰值所对应的频率和结构基本自振频率较为一致;高台基的存在改变了结构位移和加速度功率谱的大小及分布规律,且使得结构位移和加速度功率谱峰值增大。高台基对整体结构的抗震是不利的,在高台基古建筑的结构分析时必须考虑其不利影响。

In order to study the response characteristics of ancient timber buildings on the high pedestal under random earthquake excitations, the finite element models of Xi＇ an drum-tower which included the high pedestal, the upper timber structure and the overall structure were established. The reasonable earthquake vibration model was selected, and the analysis on response of drum-tower under random earthquake excitations was carried out by the absolute displacement solution based on pseudo excitation method and the harmonic response analysis of ANSYS program. The displacement and acceleration response power spectral density of the nodes of column were obtained. The results show that the peak values of the displacement and acceleration response power spectral density of structure occur at its basic frequency value. The high pedestal changes the magnitude and regularity of distribution of the displacement and acceleration response power spectral density of the structure, and also makes the peak values of the displacement and acceleration response power spectral density increase. Therefore, the high pedestal is unfavorable for the seismic performance of the overall structure and its unfavorable influence must be taken into account in structural analysis.