殿堂式古建筑木结构的离散元模拟与倒塌易损性分析

Discrete element simulation and collapse vulnerability analysis of Chinese ancient timber-frame structure

为研究中国传统殿堂式木结构古建筑在地震作用下破坏的概率以及不同参数对结构抗震性能的影响,基于按照宋代《营造法式》制作的单层单开间殿堂式木结构模型,建立了考虑榫卯半刚性连接及斗栱减震性能的三维非线性扩展离散元模型,将计算动力特性和动力响应与单向水平地震激励下的振动台试验进行了对比,并对结构的倒塌过程进行了模拟。结果表明:计算所得的结构模型自振频率与白噪声激励下试验模型误差仅为6.34%;柱头测点的相对位移时程曲线与试验实测数据基本吻合,峰值大小也基本一致;柱架和斗栱层的最大层间位移角计算值接近实测值;离散元模拟倒塌过程与试验结果相一致,表明该扩展离散单元分析方法较准确、可信;考虑了木材材性、榫卯节点刚度和斗栱刚度的影响,对以上三种影响参数分别进行折减,并建立了相应的离散元模型,通过结构动力分析得到折减模型的地震易损性曲线并与未折减模型的地震易损性曲线进行了对比,研究了不同影响参数的折减对结构倒塌概率的影响。

In order to study the probability of damage of ancient timber-frame structures under earthquake action and the influence of different parameters on the seismic performance of the structure,a single-story single-opening hall-style wooden structure model is built according to the Song Dynasty"Building Method".Based on this model,a three-dimensional nonlinear discrete element model considering the rigid connection and bucket damping performance is established.The calculated dynamic response is compared with the shaking table test under the one-way horizontal seismic excitation,and the collapse process of the structure is simulated.The results show that the error of calculated natural vibration frequency and test result under the white noise excitation is only 6.34%.The relative displacement time history curve of the stigma measurement point is basically consistent with the experimental data,and the peak sizes are basically the same.The calculated maximum interlayer displacement angle of the column and the bucket is close to the measured value.The collapse process simulated by the discrete element model is consistent with the experimental results,which demonstrates that extended discrete element analysis method is more accurate and reliable.The influence of wood material property,tenon joint stiffness and Dougong stiffness are considered,the above three influencing parameters are reduced respectively,and the corresponding discrete element model is established.The seismic vulnerability curve of the reduced model is obtained through structural dynamic analysis and compared with that of the unreduced model.Then the influence of the reduction of different parameters on the collapse probability of the structure is studied.