单围柱重檐攒尖木结构动力特性试验及地震响应分析

Dynamic characteristic test and seismic response analysis of the wooden structure with single circle of pillars and double pyramidal roofs

为研究单围柱重檐攒尖木结构的动力特性及地震响应,以西安兴庆宫五龙坛木结构建筑为例,对其进行原位动力试验,采用峰值拾取法与随机子空间法,分析了结构的前6阶自振频率、空间振型及阻尼比。考虑单围柱、榫卯连接、斗栱铺作、抹角梁架空间构造的特征,建立了单围柱重檐攒尖木结构有限元分析模型,计算得到结构的前6阶频率、振型及五龙坛原位试验结果吻合较好。结果表明:单围柱重檐攒尖木结构一阶自振频率在1.924~1.975 Hz之间,二阶自振频率在2.146~2.15 Hz之间,一、二阶振型分别为南北平动与东西平动;三阶自振频率在2.775~2.841 Hz之间,振型为扭转振动。输入不同幅值的El Centro波、Taft波及兰州波地震激励,在罕遇地震作用下底层最大层间位移角为1/83,童柱层最大层间位移角为1/87。

In order to study the dynamic characteristics and seismic response of the wooden structure with single circle of pillars and double pyramidal roofs,the Wulong Altar in Xi’an Xingqing Palace is taken as an example,in-situ dynamic tests were carried out.The natural vibration frequencies,spatial modes and damping ratios of the first six orders of the structure were analyzed by both methods,including peak picking method and random subspace method.Based on the spacial structure characteristics of single circle of pillars,mortise-tenon and Dougong bracket connections,and beam frame,the finite element analytical model of the wooden structure with single circle of pillars and double eaves was established.The calculated first six-order frequencies,vibration modes agreed well with the results of the situ test results.The results show that the first-order natural frequency is in the range of 1.924~1.975 Hz,the second-order frequency is in the range of 2.146~2.15 Hz.The first and second-order vibration modes are north-south and east-west translation,respectively.The third-order natural vibration frequency is in the range of 2.775~2.841 Hz,and the mode is torsion.El Centro wave,Taft wave and Lanzhou waves with different amplitudes are input.The maximum interstory displacement angles of the bottom and the upper layer are 1/83 and 1/87 respectively under the excitation of rare earthquakes.