面内往复荷载作用下足尺砌体填充墙的易损性研究

为了研究钢筋混凝土(RC)框架结构中砌体填充墙的地震易损性,进行了6个足尺含填充墙RC框架试件的面内往复加载试验。各试件中RC框架的设计参数均相同,其中3个试件含普通黏土砖填充墙,另外3个试件含水泥空心砌块填充墙。试验过程中,记录了砌体填充墙的损伤发展过程,并以墙体裂缝宽度和破碎坠落现象作为损伤指标,定义了"明显破坏"、"严重破坏"和"危及安全"等3个损伤状态。在此基础上,以层间位移角作为工程需求参数,建立了普通黏土砖和水泥空心砌块填充墙的易损性曲线。易损性分析结果表明,当试件的面内侧向变形达到GB 50011-2010《建筑抗震设计规范》规定的框架结构弹性层间位移角限值时,黏土砖和空心砌块填充墙均极有可能达到或超越"明显破坏"状态,且空心砌块填充墙尚有22%的概率达到或超越"严重破坏"状态。与黏土砖填充墙相比,水泥空心砌块填充墙的易损性参数具有更大的离散性,且其整体性更差,当侧向变形较大时会出现破碎砌块坠落的现象。根据试验结果,给出了砌体墙最大残余裂缝宽度、最大裂缝宽度和层间位移角之间的近似相关关系。

Seismic fragility of full-scale masonry infill subjected to in-plane cyclic loading

To study the seismic fragility of masonry infill in reinforced concrete (RC) frame structures, in-plane cyclic loading tests were conducted on six identical full-scale masonry infilled RC frame specimens, three of which were infilled with clay brick masonry and the other three with cement hollow block masonry. The damage growth of the masonry infill was recorded in detail during the test. Three damage states, namely the ‘obvious damage’, ‘severe damage’ and ‘life safety’ states, were defined for masonry infill based on crack widths and masonry spalling. Inter-story drift ratio (IDR) was taken as the engineering demand parameter for the fragility analysis of different types of masonry infill. The results show that both the clay brick and cement hollow block masonry infill are very likely to exceed the ‘obvious damage’ state, and the latter also has a considerable probability of exceeding the ‘severe damage’ state at 1/550 inter-story drift ratio, which is the elastic inter-story drift limit as per the GB 50011—2010 ‘Code for seismic design of buildings’. As compared to clay brick masonry infill, cement hollow block masonry infill exhibits larger uncertainty in its seismic fragility. It also exhibits lower integrity by the fact that broken blocks may fall at large lateral drift. Approximate relations between the maximum residual crack width, maximum crack width and inter-story drift ratio were also derived from the test results.