故宫灵沼轩钢结构动力特性与地震响应

为保护文物建筑,以故宫灵沼轩钢结构为研究对象,采用数值模拟方法,研究了该结构动力特性及地震响应。基于结构残损现状及钢结点的半刚性特性,考虑3种工况来建立灵沼轩钢结构的有限元模型。通过模态分析,研究了不同工况条件下灵沼轩钢结构的基频和主振型。通过时程响应分析,研究了8度常遇地震作用下典型节点的变形及内力响应情况,讨论了结点刚度退化对结构抗震性能的影响。通过8度罕遇地震作用下的响应谱分析,研究了灵沼轩钢结构的抗倒塌能力。研究结果表明:结点刚度退化时,灵沼轩钢结构基频减小,振动形式发生改变;8度常遇地震作用下,结构保持稳定振动状态,其变形响应峰值趋于偏大,内力响应峰值趋于偏小,且均在容许值范围内。8度罕遇地震作用下,各工况条件下的钢结构均有良好的抗倒塌能力。

Dynamic characteristic and seismic responses of steel structure of Ling-zhao Veranda in the Palace Museum

To effectively protect Chinese historic buildings, Ling-zhao Veranda in the Palace Museum was taken as example to study dynamic characteristic and seismic responses of its steel structure by finite element analysis method. Based on damage status of steel structure as well as semi-rigid characteristic of its beam-column joints, the finite element model was built considering 3 cases. By modal analysis, its basic frequencies and main modes under different case conditions were obtained. By time-history analysis, displacement, acceleration and internal force response curves of typical nodes under 8 degree intensity of frequently occurred earthquakes were obtained, and aseismic performances of the structure under different case conditions were also discussed. Anti-collapse performance of the steel structures under 8 degree intensity of rare occurred earthquakes were discussed by spectrum response analysis. Results showed that stiffness of joints of the steel structure degenerated with its basic frequency values decreased, and its main modes changed. With the 8 degree intensity of frequently occurred earthquakes, the steel structure kept stable vibration status. Due to stiffness degradation of its joints, its peak displacement response values tended to increase, and its peak internal force values tended to decrease. All peak values were within permission scopes. When 8 degree intensity earthquakes occurred, the steel structures of different cases still remained their stability.