为了研究明清时期厅堂式木结构的抗震性能,以西安城墙永宁门箭楼为研究对象,按照清工部《工程做法则例》的规制制作了缩尺比为1∶6的局部结构模型,并对其进行了地震模拟振动台试验,分析了模型结构在不同强度模拟地震激励下的动力反应和动力特性。结果表明:随着模拟地震激励的增大,结构的自振频率逐渐衰减,阻尼比逐渐增大;动力放大系数β沿模型高度逐层减小,顶部β的范围为0.166~0.633,说明结构的抗震性能良好;剪力—层间位移滞回曲线饱满,说明模型结构具有较强的耗能能力,其中柱架的耗能能力较强,占滞回耗能总量的91.8%~95.4%,在结构滞回耗能中起主要作用。研究结论对于西安城墙永宁门箭楼复建具有指导意义。
To study the earthquake resistant performance of ancient Chinese timber structures of Ming and Qing dynasty,a partial structure model with the scale ratio of 1: 6 of the embrasure watch-tower of Yongning Gate of Xi'an City wall was made according to the old engineering regulation of Qing dynasty and the shaking table test was carried out. The dynamic responses and the characteristics were analyzed. The test results show that,with the increasing of the input simulated earthquake excitation,natural frequency of the model gets smaller,while the damping ratio increases. The dynamic magnification factor β decreases along height of the model,the range of β at the model top is 0. 166 ~ 0. 633,this phenomenon indicates that the earthquake effects are isolated and reduced. Plump shear force-displacement hysteretic loop accounts for its great ability of energy dissipation. The column frame has more remarkable energy dissipation capacity than that of the Dougong layer,which accounts for 91. 8% ~ 95. 4% of total hysteretic energy dissipation and,plays a major role in hysteretic energy dissipation. The results provide a basis for rebuilding the embrasure watchtower of Yongning Gate of Xi'an City Wall.