【摘要】 四川汶川地震中,一些钢筋混凝土框架结构柱端出现严重的塑性铰,而梁端震害反而较轻,该结果不符合抗震设计的预期目标。基于地震灾区某典型框架结构的震害调查,对该框架结构进行深入的有限元仿真分析。保持该框架结构质量分布基本不变的情况下,建立3种不同的计算模型:①纯框架模型;②带楼板的框架模型;③带楼板-填充墙的框架模型。对3种模型分别进行三维弹塑性时程动力分析,分析中采用本次地震中什邡八角镇的强震记录。分析结果表明,按照规范设计的框架结构无法保证"强柱弱梁"抗震设计目标的实现;填充墙的存在影响结构的破坏机制,填充墙上下设置不均匀容易导致框架软弱层。建议框架结构的设计应充分考虑楼板和填充墙对框架抗震性能的影响,适当提高柱的刚度和承载力,结构弹塑性分析应采用考虑结构楼板和填充墙的计算模型。更多还原

【Abstract】 Many RC frame structures were severely damaged with plastic hinges formed at column ends rather than beam ends in the Wenchuan Earthquake,significantly different from the expected failure mode in seismic design code. Based on an investigation of a typical RC frame structure damaged in the earthquake area,time history analyses using a sophisticated finite element method were conducted. Three models were considered,i.e. pure frame,frame with floor slab,and frame with both floor slab and infill wall. A ground motion recorded at the town of Bajiao in the earthquake zone was used for the analyses,and comparison between the three models were carried out to investigate the effect of floor slab and infill wall on the structural base shear,distribution of plastic hinges and failure mechanism. Major findings are:① "Strong column and weak beam" cannot be guaranteed for the RC frames designed according to the current Chinese design code. ②Infill walls may significantly alter the failure mechanism of the RC frames. ③Weak story mechanism may easily occur for structures with non-uniform infill walls. These findings suggest that the effects of floor slab and infill wall should be considered in seismic design,the stiffness and strength of columns need be enhanced to achieve "strong column and weak beam" behavior,and structural elasto-plastic analysis model should take slabs and infill walls into account.更多还原