牺牲-耗能型伸臂桁架的设计和试验研究

DESIGN AND EXPERIMENTAL STUDY OF A SACRIFICIAL-ENERGY DISSIPATION OUTRIGGER

伸臂桁架是超高层建筑中的重要抗侧力构件。该文以一个超高层框架-核心筒-伸臂桁架结构为研究对象,分别采用普通伸臂桁架和防屈曲支撑(BRB)伸臂桁架进行独立设计,得到两个结构模型—普通伸臂桁架结构(CO)和BRB伸臂桁架结构(BO)。罕遇地震弹塑性分析结果表明,由于BO模型中的BRB伸臂桁架始终保持较高强度,反而导致结构中其他构件的塑性耗能比例增加,最终其塑性耗能效果不如CO模型中的普通伸臂桁架。因此,该文提出了一种新型牺牲-耗能型伸臂桁架,通过试验研究和有限元模拟分析了牺牲-耗能型伸臂桁架的主要设计参数及抗震性能。结果表明:牺牲-耗能型伸臂桁架的牺牲段和耗能段强度最优比为6∶4左右;将CO及BO模型中的伸臂桁架分别按照等刚等强原则替换成对应的牺牲-耗能型伸臂桁架后,结构中伸臂桁架的塑性耗能明显增加,剪力墙的塑性耗能明显减少,其他构件如连梁、梁的塑性耗能基本呈减少趋势,牺牲-耗能型伸臂桁架起到了保护结构中其他构件的作用。

Outriggers are key lateral force resisting members in super-tall buildings.A frame-core tube-outrigger super-tall building is chosen as the research object.The super-tall building is firstly designed through adopting conventional outriggers and buckling-restrained-brace(BRB)outriggers.Two schemes are derived after the structural design,designated as a conventional outrigger structure(CO)and a BRB outrigger structure(BO).By conducting the nonlinear time-history analyses of the two structures at maximum considered earthquake(MCE)level,it is found that the outriggers in building BO maintain high strength,which in return increases the relative ratio of dissipated inelastic energy in other structural components.Consequently,the BRB outriggers in building BO dissipate less energy than the conventional outriggers in building CO.In this study,a novel sacrificial-energy dissipation(SED)outrigger is proposed to increase the energy dissipating capacity of outriggers.The main design parameters and aseismic performance of the proposed outrigger are analyzed through both experimental studies and numerical simulations.The results indicate that the optimum strength ratio between the sacrificial part and the energy dissipating part of the SED outrigger is about 6∶4.Through substituting the outriggers in both building CO and BO with the novel SED outriggers considering the principle of equal stiffness and equal strength,the new SED outrigger structures present more rational energy dissipation modes.The dissipated inelastic energy of outriggers increases significantly while that of the shear walls and other structural components decreases.Therefore,the novel SED outrigger is able to protect other structural components of super-tall buildings under MCEs.