都市村庄底框砌体结构的动力弹塑性分析

Dynamic elastoplastic analysis of bottom frame masonry structure in urban villages

以都市村庄底框砌体结构房屋为研究对象,建立了有限元分析模型。利用分块Lanczos法计算了结构的自振周期和振型。沿纵横两个方向分别施加调幅后的El Centro地震波进行大震作用下结构的弹塑性时程分析。分析结果表明:底框砌体结构纵向刚度比横向弱;纵横两个方向在罕遇地震作用下底层框架部分均出现严重的弹塑性变形集中,层间位移大,层间位移角均不能满足现行规范的抗震设防要求;底层柱上下端、窗洞口四角和楼盖部位附近是结构薄弱环节,在较小地震加速度值下,已经出现裂缝;第2～3层砌体部分,特别是过渡层,墙体在大震下出现较多开裂,是上部砌体部分的薄弱环节。研究结果可为此类房屋的建造和改造及抗震性能评价提供技术参考。

Taking the houses of bottom frame masonry structure in urban villages as study object, this paper establishes a model of finite element analysis and uses block Lanczos method to calculate structural free vibration periods and modes. Along both longitudinal and transverse directions, E1 Centro waves adjusted in amplitude were applied to conduct elastoplastic analysis of the structure. The results show that the vertical stiffness of the structure is smaller than horizontal one;Under seldom occurred earthquake in both, the bottom frame will bring about serious concentration of elastic-plastic deformation with big story drift and the story drift angle cannot meet the demand of earthquake fortification in current code;the top and bottom ends of ground floor, four comers of a window and proximity of building roof are all weak parts of a structure, and crack will occur under a relative small acceleration; in the masonry structure of the second and third floors, particularly the transitional floor, walls which are the weak part of the masonry will have more cracks under a great earthquake. The results of the study would provide technical reference to the construction and improvement of such buildings and evaluation of seismic performance.