基于均匀层间位移的多层梁贯通式支撑钢框架简化抗震设计方法

Seismic design method of multistory concentrically braced beam-through frames aimed at uniform inter-story drift

为实现均匀层间位移的目标,提出了基于均匀层间位移的梁贯通式支撑钢框架简化抗震设计方法,设计了梁贯通式支撑钢框架。在地震作用下,作为耗能构件的只拉不压中心支撑抵抗大部分水平作用,而主体钢框架则因其可忽略的抗侧刚度而保持弹性。只拉不压支撑单元的滞回耗能作用可等效为结构的黏滞阻尼,同时支撑和框架的抗侧刚度比对结构的地震响应影响较大。基于均匀层间位移响应提出设计方法的3个性能目标,并合理考虑刚度比和等效阻尼比,给出具体设计流程。分别设计了4层和6层平面支撑钢框架模型,通过Pushover分析和弹塑性时程分析验证了该方法的合理性。分析结果表明：支撑与框架抗侧刚度比最优取值为4~6。

A seismic design procedure aimed at achieving uniform inter-story drift in multistory tension-only concentrically braced beam-through frames （TOCBBTFs） was presented. The TOCBBTF was designed so that the columns and beams would remain elastic for their negligible lateral stiffness while tension-only concentric braces resisted most of lateral loads as a reliable way of absorbing seismic energy under seismic loading. The hysteretic energy dissipation of the tension-only bracing units can be treated as supplemental damping ratio of the structure, and lateral stiffness ratio between braces and main structure exerts a significant impact on seismic behavior of the structure. Three performance objectives of seismic design procedure aiming at uniform inter-story drift along the building height were established first. From the perspective of supplemental viscous damping and proper lateral stiffness of the structure, the seismic design procedure was proposed and applied to 4- and 6-story model structures to demonstrate the design procedure. Pushover analyses and time-history analyses were carried out to verify whether the pre-specified performance objectives were achieved or not. The analysis results show that the reasonable lateral stiffness ratio between braces and main structure is from 4 to 6 and the proposed design procedure agrees very well with the pre- specified design objectives.