防屈曲支撑、普通和特殊中心支撑钢框架结构抗震性能分析

Seismic Response Analysis of Steel Frames Braced with Buckling-Restrained,Ordinary and Special Concentrically Braces

基于考虑人字形防屈曲支撑屈服后超强和几乎不再对被撑梁提供竖向支点作用这两个因素,本文提出了采用该种支撑的钢框架结构的设计方法,并分别对采用普通及特殊中心支撑和防屈曲支撑的框架结构的抗震性能进行了对比分析。结果表明,虽然防屈曲和特殊中心支撑框架结构的层间侧移总体上大于普通中心支撑框架结构,但前者的基底剪力却大大低于后者。罕遇地震下,三种结构中的柱子基本保持弹性,普通和特殊中心支撑出现了大幅的平面外失稳,而防屈曲支撑在拉压作用下均进入屈服耗能。三种结构中被撑梁的最大挠度在支撑屈服或失稳前后分别出现在撑点两侧和撑点位置。屈服后的防屈曲支撑几乎不产生对被撑梁竖直向下的不平衡剪力,而失稳后的普通和特殊中心支撑则对被撑梁产生较大的不平衡剪力。

Based on the facts of overstrength of the postyield chevron buckling restrained brace （BRB） due to the strainhardening effect and almost without vertical support for the braced beam by this brace, a method for design of the frame with buckling-restrained braces （BRBF） is proposed in this paper. Furthermore, a seismic response analysis has been carried out on the special concentrically braced frame （SCBF） and the ordinary concentrically braced frame （OCBF） to compare the aseismic performance of the BRBF. The analysis reveals that, although the story drift of the BRBF and SCBF are slightly larger than those of the OCBF, the first story shear forces of the former are greatly smaller than those of the latter. Under severe earthquakes, columns in three kinds of the structures remain elastic. For most OCBs and SCBs, the out of plane flexural buckling occurs. Whereas, the buckling-restrained braces can yield in both tension and compression, exhibiting better energy dissipation capacity. The maximum vertical deflection of the beam connected by the braces occurs in the segments of beam between the column and braced points before the braces yielding or buckling, whereas at the braced points after the braces yielding or buckling. Compared with the larger vertical shear forces from the braces to the braced beams in the OCBF or SCBF after the braces buckling, smaller such shear forces occur in the BRBF after the braces yielding.