故宫灵沼轩的动力特性及抗震性能研究

故宫灵沼轩是我国最早建造的钢铁-砌体组合结构之一,具有重要的历史、艺术和科学价值。为了评估灵沼轩在地震作用下的结构安全状况,建立了灵沼轩结构的三维有限元模型,并对其进行了动力特性和地震时程分析,得出了其固有频率、模态振型、地震位移响应和地震应力响应。结果表明:灵沼轩整体结构布置对称性较高,扭转刚度较大,对抗震较为有利;在8度多遇地震、设防地震和罕遇地震作用下,灵沼轩的金属结构部分及砌体结构部分的顶点位移和层间位移角均符合现行规范要求,砌体结构部分的第三主应力响应均小于材料的抗压强度,不存在压溃风险。在8度多遇地震和设防地震作用下,砌体结构部分的第一主应力响应均小于材料的抗拉强度,结构不会发生拉裂。但在8度罕遇地震作用下,砌体结构的部分位置拉应力超过材料的抗拉强度,这些位置存在开裂危险。最后,综合动力特性和抗震性能分析的结果,提出了灵沼轩的抗震加固建议。

Research on dynamic properties and seismic behavior of Lingzhao Xuan in the Forbidden City

Lingzhao Xuan in the Forbidden City is one of the oldest steel-masonry composite structures in China. The building has very important historical, artistic and scientific value. In order to evaluate the structural safety of the building under earthquake conditions, we set up a three-dimensional finite element model to analyze its dynamic properties and earthquake response in order to obtain natural frequencies, modal modes, the earthquake displacement response and the earthquake stress response. The results show that the structure of Lingzhao Xuan is very symmetric and its torsional rigidity is large, which is better for the seismic behavior of this building. Under conditions of 8-degree frequently occurring earthquake, 8-degree fortification earthquake or 8-degree rarely occurring earthquake, the maximum displacement and the maximum story drift of the building can meet the requirements of the present codes, and the maximum compressive stress of this building is lower than that of the masonry, so the building has no fracture failure. Under conditions of 8-degree frequently occurring earthquake or 8-degree fortification earthquake, the maximum tensile stress of this building is lower than that of the masonry, so the building has no cracking failure. However, under conditions of 8-degree rarely occurring earthquake, the maximum tensile stress of some parts is larger than that of the masonry, and these position will have cracking failure. Finally, the seismic strengthening strategy of this building is presented based on the results of the dynamic properties and seismic behavior analysis.