基于环境激励测试的开元寺塔动力性能分析

Dynamic performance analysis of Kaiyuan pagoda based on ambient vibration test

采用环境随机激励技术对定州开元寺塔的动力特性进行现场测试,提出一种新的空间测点布置方案——同向平行测试法,利用该方法可以对开元寺塔平动及扭转模态分量进行有效测量。基于现场实测数据,结合Welch自功率谱密度法和随机子空间法得到砖塔的自振频率、振型等参数,并反演推算出砖塔结构的层间刚度。研究表明砖塔东北侧新砌筑结构层间刚度普遍大于东南侧旧塔体结构,随着高度的增加砖塔的层间刚度逐渐减小。基于动力测试分析数据,建立并修正了ABAQUS有限元模型。有限元模型模态分析结果与实测结果对比误差较小,说明模型较为可靠,可以为古塔的后续动力响应分析提供数值模型。

In this work,the dynamic characteristics of Kaiyuan pagoda were tested by the ambient vibration test technique,and a new arrangement scheme of spatial measuring points( Co-parallel test) was proposed to effectively measure the translational and torsional modal components of the pagoda. The natural frequency and vibration mode were obtained by using Welch self-power spectral density function and stochastic subspace identification method. By referring to the structural dynamics theory and the measured results,the inter-floor stiffness of the two orthogonal directions of the northeast and northwest of the pagoda were derived. Based on the ABAQUS platform,the finite element model was established. Compared with the actual measurement,the modal analysis result of the numerical model has smaller error,indicating that the model is reliable and can provide a numerical model for the subsequent dynamic response analysis of the pagoda.