故宫太和殿动力特性与常遇地震响应

Dynamic characteristics and seismic responses of the Forbidden City's Tai-he Palace to frequently occurring earthquakes

为更好地保护故宫太和殿,采用有限元分析方法,研究了太和殿的动力特性及常遇地震作用下的响应。采用弹簧单元模拟榫卯节点及斗拱构造,并考虑柱础为铰接,建立了太和殿有限元模型。通过模态分析,获得了太和殿基频及主振型;通过对模型进行时程分析,获得了典型节点的位移、加速度响应曲线,以及典型单元的内力响应曲线,评价了太和殿的抗震性能。结果表明:太和殿基频为0.9Hz,主振型以平动为主;常遇地震作用下,太和殿能保持稳定振动状态,结构的内力和变形均在容许范围内,且斗拱及榫卯节点均能发挥一定的减震作用。

To effectively protect the Forbidden City＇s Tai-he Palace,its dynamic characteristics and seismic responses to frequently occurring earthquakes were studied by finite element analysis methods. Based on hypotheses that tenon-mortise joints and bracket sets were simulated by spring elements,and that column roots were of swivel restriction,a finite element model of Tai-he Palace was built. By modal analysis,the basic frequency and main modes of the palace were obtained; from time-history analysis,displacement and acceleration response curves of typical nodes,and internal force response curves of typical elements were obtained. Analysis shows that basic frequency of Tai-he Palace is 0. 9 Hz and that its main modes are of translation. During frequently occurring earthquakes,the structure vibrates steadily,although its peak displacement as well as internal force response values are within permitted limits. From this,it can be concluded that tenon-mortise joints and bracket sets are helpful for seismic mitigation of of damage to the structure.