跨地裂缝结构地震作用下的损伤分析与评估研究

Damage analysis and evaluation of frame structure spanning over ground fissure under seismic load

为研究跨地裂缝结构地震作用下的损伤机理与评估方法,通过缩尺比例为1/15的五层跨地裂缝框架结构模拟振动台试验,获得了不同地震波作用下该结构的自振频率变化和裂缝发展规律;采用加权系数法对模型结构进行损伤评估分析,并验证了该评估方法的可行性和合理性。同时采用ABAQUS有限元软件建立了结构跨越地裂缝和处于无地裂缝场地两种分析模型,进行了在高烈度地震作用下跨地裂缝结构构件和整体损伤分布规律的研究,以确定跨地裂缝结构损伤位置和损伤程度的内在关系。研究结果表明:跨地裂缝结构构件损伤分布表现出明显的上、下盘规律,即距地裂缝相同位置处,地裂缝上盘的梁柱构件损伤指数均大于下盘构件;跨地裂缝结构底层损伤指数远大于其他楼层,底层是该类结构的薄弱层;在相同峰值加速度地震作用下,处于非地裂缝场地结构整体损伤指数小于跨地裂缝结构,地裂缝的存在加剧了上部结构的损伤破坏。

To study the damage mechanism and to propose an evaluation method for the structure spanning over ground fissure,a shaking table test on a 1/15-scale model of a five-story RC frame spanning over ground fissure was conducted.According to the test results,variation of the frequency and crack development under different earthquake waves were obtained.A seismic damage model based on weighted combination method was used to evaluate the damage of the model structure.The feasibility and accuracy of this evaluation method were verified.Two analysis models of the structure spanning over ground fissure and another structure in the same site without spanning over the ground fissure were established by the finite element software ABAQUS.To determine the internal relationship between the damage location and the damage degree of the structure spanning the ground fissure,the influence of ground fissure on damage distribution of structural members and overall structural damage was analyzed.The research shows that the damage distribution of the structural members is affected by the hanging-wall/footwall effect for the structure spanning over the ground fissure.At the same distance from the ground fissure,the damage indices of the members on the hanging-wall were greater than those on the footwall.The damage index of the ground floor was much larger than that of other floors,so the ground floor was the weak floor of the structure spanning over the ground fissure.Under the seismic wave with the same peak acceleration,the overall damage index of the structure spanning over the ground fissure was greater than that of the structure in the site without spanning over the ground fissure,indicating that the existence of the ground fissure increased the level of damage of the structure.