地裂缝环境下钢筋混凝土框架结构的地震响应

为了研究地裂缝场地钢筋混凝土（RC）框架结构的地震响应规律，采用ABAQUS有限元分析软件，建立地裂缝场地土与结构体系的三维数值模型. 将计算结果与跨地裂缝结构模型试验结果进行对比，验证了数值模拟方法的可行性. 通过对框架结构位移角、层间剪力、结构总水平地震作用的定量分析，获得地裂缝对框架结构动力响应的影响规律及影响范围. 研究结果表明，地震作用在地裂缝场地表现出的非一致性加重了上部结构的损伤程度，结构中间跨的构件及节点破坏尤其严重，上盘结构的裂缝长度和宽度更大. 框架结构跨越地裂缝是最不利的布置形式，动力响应尤为剧烈，在结构设计时应尽量避免. 近地裂缝场地上盘结构的响应程度大于下盘，表现出“上、下盘效应”，在上盘0~20 m和下盘0~15 m范围内，框架结构破坏严重，在上盘30 m和下盘20 m外，结构反应显著减小.

Seismic response of reinforced concrete frame structure in ground fissures area

The three-dimensional numerical model of soil and structure system of the ground fissures site was established by the finite element program ABAQUS in order to analyze the seismic response of the reinforced concrete (RC) frame structure in ground fissures area. The calculation results were compared with the results of the shaking table test for the frame structure crossing ground fissures, and the feasibility of numerical simulation method was verified. Laws and scopes for the effects of the ground fissures on the frame structure under earthquake action were obtained based on the quantitative analysis of the displacement angle, inter-story shear force and total horizontal seismic action of frame structure. Results show that excitation of the non-uniform seismic excitations in the ground fissures site aggravates the damage of the superstructure. The damage of members and joints across the middle span of RC frame structure is more serious. The length and width of cracks of structure on the hanging-wall are more than those on the footwall. The frame structure crossing ground fissures is the most unfavorable layout. The dynamic response of this structure significantly increases, so it should be avoided as far as possible in the structural design. The dynamic response of the frame structure on the hanging-wall is much larger than that on the footwall, showing "hanging-wall/footwall effect". The frame structure is seriously damaged in the range of 0~20 m in the hanging-wall and 0~15 m in the footwall near the ground fissures. The dynamic response of the structure significantly decreases in the hanging-wall 30 m away and in the footwall 20 m away.