设计偏心距对偏心结构弹塑性扭转反应的影响

通过对三片抗侧力单元构成的偏心结构进行弹塑性时程分析,研究了弹塑性侧扭耦合反应与输入地震动强度之间的关系.随着输入地震动强度的增大,结构扭转反应经历3个阶段的变化,在弹性范围内扭转角单调增大,开裂后逐渐减小,屈服后则继续增大.扭转对侧向振动的影响则逐渐减小,侧扭耦合程度逐渐降低.分析结果表明:通过设计偏心距对偏心结构进行强度分配,可以控制弹塑性扭转反应并提高结构侧向变形能力.设计偏心距的不同取值,对刚性边构件的屈服水平和延性需求的影响最大.文章还对偏心结构基于性能的抗震设计进行了展望.

Influence of Design Eccentricity on the Inelastic Torsional Response of Asymmetric Structure

Inelastic time-history analysis was performed on a single-story asymmetric structure with three lateral force-resisting elements.The relationship of torsional response and the peak ground motion acceleration(PGA) were studied.The results showed that at the elastic stage the torsion increased as the PGA rose,after crack the torsion decreased,and again increased after yielding.In the inelastic stage,the torsion contributed less to lateral deformation than in elastic stage.It was indicated that distributing the strength according to design eccentricity could reduce the inelastic torsion of asymmetric structures.And different design eccentricity may result in different yielding level and ductility demand of elements at stiff side.Performance-based seismic design of asymmetric structure was discussed at the end of this paper.