地震作用下RC框架结构损伤演化过程分析

Damage evolution process of RC frame under earthquake excitation

为明确RC框架结构的抗地震倒塌破坏机理,控制其失效路径,基于课题组完成的1榀1/3比例的3层三跨RC平面框架低周循环加载试验,通过量化构件、楼层及结构3个层次的损伤破坏程度,研究了不同层次损伤破坏之间的相互联系以及不同类型构件损伤程度对结构整体抗震性能的影响。研究结果表明:结构发生倒塌破坏时,底层构件损伤程度普遍大于上部构件,第1~3层梁、柱端的损伤指数平均值分别为0.95、0.86、0.74和0.97、0.62、0.15,地震作用下结构的累积损伤是自下而上发展的;框架梁作为耗能构件,一般先于框架柱出现损伤,且损伤程度较大,沿楼层分布比较均匀,结构最终倒塌时第1层框架梁的损伤指数分别比第2、3层增加约8.89%和21.06%,框架柱的损伤破坏沿楼层分布相对集中,主要分布于结构底层,最终倒塌时第1层框架柱的损伤指数分别比第2、3层提高约26.56%和62.93%;结构在加载位移幅值较小时,主要依靠水平耗能构件消耗地震能量,随着位移幅值及循环次数的增加,竖向承力构件逐渐取代水平构件的耗能作用,框架梁、柱的整体损伤发展曲线分别呈上凸和上凹趋势;从结构能量耗储能力角度提出的整体损伤模型更符合结构抗震的本质,未知参数少,且计算结果能够较为准确地反映结构在不同性能水平下的损伤状态。

In order to clarify theseismic collapse mechanism of RC frame structures and control their failure path,the damage degree of component, storey, and structure was quantitatively studied based on a 1/3-scale model of three-storey and three-bay frame, was carried out under low reversed cyclic loading. The influence of component damage was analyzed and the relationship between different levels was discussed on the seismic behavior of structure. The results show that the damage degree of the bottom members is generally greater than that of the top ones when the structure collapses. The average damage indexes of columns in different stories are 0.97, 0.62, 0.15, and those of beams are 0.95, 0.86, 0.74, respectively. The cumulative damage of the structure develops from the bottom to the top. As the energy dissipation member, the frame beams are damaged before the columns, with more serious degree and uniform distribution along the floor. The damage distribution of columns along the floor is relatively concentrated. When the structure collapses, the damage indexes in the first story are larger than those of the upper ones, about 8.89%, 21.06% of beams and 26.56%, 62.93% of columns.When the load displacement is small, the structure relies on horizontal components to consume seismic energy, however, it gradually relies on vertical components as the displacement amplitude and cycle number increase. The damage development curves of beams and columns show a convex and concave tendency, respectively. The damage model proposed from the perspective of structural energy dissipation is more consistent with the nature of structural seismic resistance, with fewer unknown parameters, and the calculation results can accurately reflect the damage state of the structure at different performance levels. 2 tabs, 14 figs, 25 refs.