考虑楼梯影响的框架结构地震响应分析

汶川地震震害表明,楼梯间是结构的易损部位,新版抗震规范中强调了楼梯对于结构的重要性。为了分析楼梯对框架结构抗震性能的影响,应用SAP2000软件通过对比有无楼梯参与整体结构计算分析,得到了楼梯对整体结构自振特性、结构整体反应、多遇地震下梯板及其周边构件受力的影响以及罕遇地震下结构塑性铰的分布。结果表明,楼梯的存在改变了结构振型的出现顺序,使结构的扭转效应增强;楼梯间周围构件有楼梯参与计算后受力变化较大;地震作用下,梯板承受较大的轴力和剪力,应该按照拉(压)弯构件进行设计;罕遇地震下,有楼梯模型结构的塑性铰数量要明显多于无楼梯模型。因此,对于框架结构的设计有必要考虑楼梯的影响。

Earthquake Response Analysis of Frame Structure Considering Stair Influence

Wenchuan earthquake shows that the staircase is damaged easily under the earthquake.Also the new seismic code stresses the importance of staircase in the structure.To study the influence of stair for the seismic performance of frame structure,the influence caused by stairs on the whole structural dynamic property,the whole response of structure,the influence of element force for stair plate as well as periphery elements under frequent earthquake and the hinge distribution of structure under rare earthquake are obtained by comparing the computational analysis results between the structure with stair and the structure without stair using the software of SAP2000.Through the analysis,some valuable conclusions are obtained.The order of the modes of the structure maybe changed by the stairs,and the torsional effect of structure is increased;the members force around the stair greatly changed when considering the stair influence.The axial force and shear force of the stair plate are big,the stair plate should be designed by the state of tension-moment or compression-moment element.The elasto-plastic hinge number of the structure with the stair are more than the structure without stair.It is necessary to consider the stair when analyzing the frame structure.