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主要研究地面运动的频率成分在非弹性需求下对单自由度(SDF)和多自由度(MDF)钢架结构的作用。通过对文献进行详细的审查,识别出最能代表地面运动频率成分的指标。选择地面运动的平均周期(Tm)是由于它能区别各种不同地面运动的频谱形态及其与震级、距离和场地特征的关系。首先使用一组128次地面运动的记录根据Tm对单自由度体系在特定延性水平时的非弹性位移要求进行研究。然后通过采用相同的地面运动资料做增量动力分析,把研究扩展到多自由度系统,评价Tm对各种工程需求参数的影响。得到的结果表明,对于单自由度体系,当弹性周期(Te)与Tm的比值低于1时,位移将增大。对于多自由度体系,结果证明了高阶振型对于基底剪力的影响和当Tm接近结构的高阶振型周期时,对最大层间侧移的影响变得更加显著。对单自由度体系和多自由度体系,在非弹性水平较高时这些观测更为明显。研究结果对于欧洲抗震设计法是尤为重要的。
This paper mainly studies the effect of frequency components of ground motion on single degree of freedom (SDF) and multi-degree-of-freedom (MDF) steel structures under inelastic requirements. A detailed review of the literature identified the most representative of the ground motion frequency components. The mean period (Tm) of surface movement is chosen because of its ability to tell the spectrum shape of various ground motions and their relationship to magnitude, distance, and site characteristics. First, a set of 128 ground motion records were used to study the inelastic displacement requirements of a single-degree-of-freedom system at a particular level of ductility based on Tm. Then, by using the same ground motion data to do incremental dynamic analysis, the research is extended to a multi-freedom system to evaluate the effect of Tm on various engineering requirements parameters. The obtained results show that the displacement will increase when the ratio of elastic period (Te) to Tm is lower than 1 for a single degree of freedom system. For a multi-degree-of-freedom system, the results demonstrate the effect of the higher-order modes on the substrate shear and the effect on the maximum inter-story shift becomes more pronounced as the Tm approaches the higher-order modes of the structure. For single-degree-of-freedom and multi-degree-of-freedom systems, these observations are more pronounced at higher levels of inelasticity. The results of the study are particularly important for the European seismic design method.