基于谱匹配的近远场地震动作用下RC框架结构易损性分析

中文摘要: 选择合适的地震动输入是进行结构非线性动力分析和增量动力分析的基础。首先选取实际近场和远场地震动记录各20条，并运用谱匹配方法对其进行目标设计谱匹配，得到谱匹配后的近场和远场地震动记录各20条。选择地震动最大峰值速度（ PGV）和结构基本周期对应加速度反应谱 S a（ T 1）值为强度指标，输入4组地震动记录，对一5层钢筋混凝土框架结构，分别进行单一地震动强度水平的非线性动力分析和多重地震动强度水平的增量动力分析，提取工程需求参数如最大层间位移角和最大残余层间位移角，进而分析反映谱匹配效果的偏差指标和工程需求参数的离散性及其与地震动强度指标的相关性。最后，基于增量动力分析结果对结构进行了不同损伤状态下的易损性分析。分析结果表明：工程需求参数分析结果与 PGV的相关性明显优于与 S a（ T 1）的相关性；输入谱匹配后的近场和远场地震动记录，工程需求参数分析结果的离散性明显降低且最大层间位移角明显偏差；以 PGV为强度指标，相同 PGV时远场地震动引起的结构最大层间位移角较大，而以 S a（ T 1）为强度指标，相同 S a（ T 1）时则是近场地震动引起的结构最大层间位移角较大；结构倒塌前，近场地震动作用下各损伤状态对应的最大残余层间位移角较大，达到倒塌状态时，近场地震动作用下结构的最大残余层间位移角较小。
Abstract:Choosing the appropriate ground motion as input is the basis of nonlinear dynamic analysis and incremental dynamic analysis of structures.Firstly,20 suites of near-field ground motion records and 20 suites of far-field ground motion records were chosen and modified to match the targeted design spectrum.Then,taking peak ground velocity ( PGV) and spectral acceleration corresponding to the fundamental period of the structure S a( T 1) as intensity measures,dynamic analysis with the single ground motion intensity level and incremental dynamic analysis (IDA) with multiple ground motion intensity levels were conducted on a 5-storey reinforced concrete frame under the aforementioned 4 sets of ground motion records.Engineering demand parameters ( EDS S) such as maximum inter-story drift ratios ( θ max) and maximum residual inter-story drift ratios ( RIDR max) were obtained.The bias indices to represent the spectral matching effect,the variation of EDP S and the correlation between EDP S and intensity measures were further analyzed.Finally,seismic fragility analyses corresponding to different damage states were conducted based on IDA results.The analytical results showed that the correlation of EDP S with PGV is better than with S a( T 1).Under spectrum-matched near- and far-field ground motion records,the dispersion of EDP S decreases obviously and there is no obvious biases in θ max results.If taking PGV as intensity measure,far-field ground motion induces larger θ max than near-field ground motion.On the contrary,if taking S a( T 1) as intensity measure,near-field ground motion induces larger θ max than far-field ground motion.Prior to collapse of the structure, RIDR max values corresponding to different damage states under near-field ground motion are larger than the values under far-field ground motion.For collapse state, RIDR max values under near-field ground motion are less than the values under far-field ground motion.