ABSTRACT

A performance-based hybrid force/displacement (HFD) seismic design method for space steel moment resisting frames irregular in plan view and in elevation is developed. Irregularity in elevation is either due to non-uniform distribution of mass or due to the presence of setbacks along the height of the frame. More specifically, 30 different frames irregular in plan view for the first case (plan-irregularities), 40 frames with setbacks (vertical stiffness irregularities) for the second case, and 18 frames with mass discontinuities (vertical mass irregularities) at the first, intermediate and top storey for the third case are considered. All these frames are designed according to Eurocodes 3 and 8 and subjected to 42 pairs of ordinary ground motions. Through nonlinear seismic analyses, seismic response databanks for these three types of irregular frames are generated corresponding to four performance levels. These databanks are then utilized for the development of simple expressions that determine the behavior (or strength reduction) factors of the frames. These are functions of frames geometrical/dynamic characteristics including measures of their irregularities as well as the target maximum interstorey drift ratio and member local ductility. The proposed design method, even though it is mainly a force-based design method, controls deformation and therefore damage through the proposed deformation-controlled behavior factors. Design examples are presented to validate the effectiveness of the method to account for the irregularity effects on the preliminary design stage while time-history analysis results demonstrate its advantages to control better the inelastic response of the frames over the conventional force-based seismic design method of Eurocode 8.

摘要

针对平面和立面不规则的空间钢抗弯框架，开发了一种基于性能的混合力/位移（HFD）抗震设计方法。高度的不规则性要么是由于质量分布不均匀，要么是由于沿框架高度存在挫折。更具体地说，对于第一种情况（平面不规则），30 个不同的框架在平面图中不规则（平面不规则），对于第二种情况，有 40 个具有缩进（垂直刚度不规则）的框架，以及在第一个、中间有质量不连续（垂直质量不规则）的 18 个框架考虑第三种情况的顶层。所有这些框架均根据欧洲规范 3 和 8 设计，并经受 42 对普通地面运动。通过非线性地震分析，这三种类型的不规则框架的地震响应数据库对应于四个性能级别生成。然后将这些数据库用于开发确定框架的行为（或强度降低）因素的简单表达式。这些是框架几何/动态特性的函数，包括测量它们的不规则性以及目标最大层间漂移比和构件局部延性。所提出的设计方法，尽管它主要是一种基于力的设计方法，但通过所提出的变形控制行为因素来控制变形，从而控制损坏。