归一化时-频反应谱与结构损伤曲线的应用

Application of normalized time-frequency response spectrum and structural damage curve

为了研究归一化时-频反应谱和结构损伤曲线在抗震设计中的应用价值,对某十层RC框架结构采用地震动特性截然不同的唐山地震天津波SN方向和集集地震波SN方向进行弹塑性时程分析,对比了2种工况下结构损伤曲线在地震波归一化时-频反应谱上的表现.结果表明,结构的最大地震反应并不一定造成结构最大破坏,而随后很小的反应也可能最终导致结构倒塌,选用不合理的地震记录进行抗震设计是不可靠的,故传统的反应谱理论存在一定的局限性.结构损伤曲线通过自振周期的变化可以反映结构的塑性发展,与同时具备地震动三要素(振幅、频谱和持时特性)的归一化时-频反应谱相结合,可有效预测结构的损伤机制,从而为大震下结构的抗倒塌设计提供参考依据.

In order to investigate the application of normalized time-frequency response spectrum and structural damage curve, a 10-storey reinforced concrete frame structure subjected to Tianjin record （SN direction） in Tangshan earthquake and ChiChi record （SN direction） whose seismic characteristics are completely different is studied by using elastoplastic time-history analysis. The performances of structural damage curves of the two cases on normalized time-frequency response spectrums are compared. The results show that the maximum seismic response of structures may not always result in the maximum damage, but the subsequent small seismic response may lead to the overall collapse of structures. Aseismatic design with unreasonable seismic record is not reliable. Therefore, there are some limitations in traditional response spectrum theory. Structural damage curve, which can reflect plastic development of structures through variations of structural natural vibration periods, together with normalized time-frequency response spectrum which contains the three features of earthquake motions （amplitude, frequency and duration） can effectively predict structural damage mechanism, which provides reference basis for aseismatic design of structures subjected to severe earthquake.