横梁加强型人字撑结构的弹塑性滞回性能

HYSTERETIC BEHAVIOR OF CHEVRON BRACE PAIRS WITH STRONG BEAM

人字形支撑是多高层钢结构建筑的一种常用支撑形式。在侧向荷载作用下,由于受压支撑发生屈曲,承载能力快速下降,支撑架的横梁会受到拉压支撑间的竖向不平衡力的作用,JGJ 99—98《高层民用建筑钢结构技术规程》规定需加强支撑架横梁来承受这一不平衡力的作用。静力弹塑性推覆分析的结果显示,在加载后期横梁受拉支撑屈服荷载对加强型人字撑结构抗侧能力有很大的贡献。但是,在强烈地震作用下,由于每一支撑均处于拉压交替的受力状态,因此支撑架的受力性能要复杂得多。通过对横梁加强型支撑结构在往复荷载和地震荷载作用下的抗侧性能进行研究,以更好地了解这种支撑结构的抗震性能。

Chevron braces are commonly used in tall steel building structures.The compressive brace of this bracing system may experience dramatic strength degradation after buckling,which leads to the formation of a vertical unbalance force in the intersection point of the compressive and tensile braces.Thus,the beam of the chevron braced frame should be designed as a ＂strong beam＂,i.e.capable of resisting this vertical unbalance force.The results of static push-over analyses showed that the lateral force resistance of a chevron braced frame with strong beam depends largely on the yielding load of the tensile brace.However,each of the bracing members is in the compressive or tensile load alternatively when the braced frame undergoes the severe seismic action,and thus the behaviour of the braced frame is more complicated in this case than that revealed via the push-over analysis.It was carried out a series of analyses on the performance of the chevron braced frames under cyclic and seismic loads.