成束钢框筒结构罕遇地震作用下的能量反应分析

Steel bundled-tube structural energy response analysis under rare earthquake

基于对三种不同竖向收进方式的成束钢框筒结构进行的罕遇地震作用下的弹塑性时程分析,得到各种能量项数值,分析了采用不同峰值加速度输入下各能量项时程曲线的变化趋势。对输入能与地震加速度的关系、塑性耗能沿楼层的分布规律以及塑性耗能在构件中的分配进行了研究。探讨了组成束筒的各单个框筒的塑性耗能特点及其与竖向收进方式的关系。结果表明:采用不同的峰值加速度输入不影响弹性应变能、塑性耗能、阻尼耗能以及动能各项占总输入能比例的时程曲线变化趋势;当地震作用超过一定强度时,动能和弹性应变能在输入能中所占的比例变小,输入能主要依靠结构的塑性耗能来耗散;输入峰值加速度不同,塑性耗能沿楼层的分布规律也不同;窗裙梁是成束钢框筒结构最主要的耗能构件;组成束筒的各单个框筒耗能与输入的地震动峰值加速度有关;当输入的峰值加速度较大时,对于竖向未收进的模型,中间部位筒的耗能小于其周边筒的耗能,对于竖向收进的筒体,除收进变化较大的个别单筒外,单筒各层平均耗能较为均匀。

Elasto-plastic time-history analysis of structure under rare earthquake was used to analyze three steel bundled-tube structure models with different setbacks. Based on the energy items, distribution of energy curves under different peak acceleration waves, relation between input energy and wave acceleration, distribution of plastic energy dissipation along structural height and in structural members have been studied. The plastic energy dissipation of each single tube formed bundled-tube and the influences by vertical setback were also discussed. The results show that different peak acceleration inputs can not affect the change trend of elastic strain energy, plastic energy dissipation, damping energy consumption and proportion of kinetic energy in the input energy. When the earthquake exceeds a certain intensity, the proportion of kinetic energy and elastic strain energy in the input energy can be reduced, and the input energy can be dissipated mainly by the plastic energy dissipation of the structure. The peak acceleration of input ground motion is different, and the distribution of plastic energy dissipation along the floor is also different. The spandrel beams are the most important energy dissipation members. The energy dissipation of single tube is related to the input ground motion peak acceleration . When the input peak acceleration is large, as for models without vertical setback, energy dissipation in the middle part of the bundled-tube is less than the energy dissipation of the surrounding. Except for the single tube with large variation, the average plastic energy dissipation per floor of single tube is uniform for models with different setbacks.