不对称收进框架-核心筒-伸臂高层结构抗震性能分析与设计

Performance-based seismic analysis and design of asymmetric vertical setback high-rise structure with frame-core tube-outrigger system

为研究不对称竖向收进高层结构的抗震性能,结合某233.1 m超限工程实例进行结构抗震性能分析与设计。结构采用钢管混凝土框架-核心筒-伸臂桁架体系,基于性能化抗震分析方法,对该结构进行多遇地震反应谱和时程分析、设防地震等效弹性分析以及罕遇地震弹塑性时程分析,获得了竖向不对称收进高层结构的楼层位移角和剪力分布,研究了伸臂桁架及核心筒等构件的抗震性能。结果表明,设置伸臂桁架后结构在多遇地震作用下的X向层间位移角由1/474减小至1/593,小于规范规定的层间位移角限值1/533;伸臂桁架构件尺寸应由设防地震作用确定,通过持续增加杆件尺寸并不能有效降低伸臂桁架杆件应力比;结构外框架承担的楼层剪力比最小为5.22%,外框架和核心筒能够形成双重抗侧力体系;伸臂楼层的外框架承担的楼层剪力比达到55.3%,表明伸臂桁架加强了外框架和核心筒的协同工作能力;设防地震作用下,结构底部加强区剪力墙等效拉应力小于混凝土抗拉强度标准值,对于个别等效应力较大的墙体应增加配筋予以加强;罕遇地震作用下,核心筒剪力墙轻微损坏,剪力墙损伤明显区域集中于伸臂桁架楼层及其相邻上部楼层,连梁损伤因子超过0.5,伸臂桁架满足预定的性能目标。

To study the seismic capacity of asymmetric vertical setback high-rise structure,the seismic performance analysis and design of overrun project with height of 233.1 m were carried out,and concrete filled steel tubular frame-core tube-outrigger structure system was adopted.Based on the performance-based seismic analysis method,the seismic response spectrum and time history analysis,the equivalent elastic analysis of fortification earthquake and the elasto-plastic time history analysis of rare earthquake were carried out,and the inter-story drift angle and shear distribution,the seismic performance of outrigger truss,core tube and other components of the vertical asymmetric setback high-rise structure were studied.The results show that the inter-story drift angle of the structural X direction under frequent earthquake action is reduced from 1/474 to 1/593 when the outrigger truss is installed,which is less than 1/533 of the code limit value.The component dimension of outrigger should be determined based on fortification earthquake action,and the stress ratio of outrigger truss members can’t be effectively reduced by increasing the size of outrigger members.The minimum floor shear ratio of the outer frame is 5.22%,which shows that double lateral resistance system of the outer frame and the core tube can be formed.The floor shear ratio of the outrigger floor reaches up to 55.3%,which indicates that the outrigger enhances the cooperative working ability of the outer frame and the core tube.The equivalent tensile stress of the shear wall in the bottom reinforcement area is less than the standard value of concrete tensile strength under the fortification earthquake action,and shear wall should be reinforced when equivalent tension stress exceeds the standard value of concrete tensile strength.The core tube shear wall is slightly damaged under rare earthquake action,and the obvious damage area of shear wall is located in the outrigger floor and its adjacent upper floor.The damage factor of coupling beam is more than 0.5,and the performance objective of outrigger truss can be satisfied.