Regional Differences in Global Ground Motion and Their Applicability to Engineering Inputs
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摘要: 工程结构动力时程分析时在本地区观测记录不足的情况下,时常选用其他国家或地区的强震动记录作为地震动输入,但这些记录是否适用于我国规范要求的场景尚缺乏科学的验证。本文搜集了美国、欧洲、新西兰、日本以及墨西哥地区近十年浅层壳内地震共
1697 组强震动观测记录,分析相同场地类别条件下这些记录的归一化反应谱与我国规范设计谱的匹配效果,从全周期、分周期段谱形匹配的角度,验证这些国家和地区的地震动记录作为我国工程结构时程分析地震动输入的适用性,得到如下结论:(1)通过比较不同国家间地震动的归一化反应谱,验证了地震动存在显著的区域性差异,说明地震动输入选取时要尽可能选用工程场址所在地区的观测记录。(2)通过对比近、中、远场的归一化平均谱,发现短周期地震动的区域性差异在近场并不突出,地震动输入选取还需考虑距离因素。(3)依据谱形匹配的平均相对误差、平均变异系数和观测记录数量,给出了国外强震动记录是否适用于我国地震动输入选取的评价流程。(4)分别从全周期以及短、中、长分周期段谱形匹配效果的角度,给出了不同场地类别下我国地震动输入选取时最优推荐强震动记录的国家或地区,发现在短周期段新西兰的记录最适用,而中、长周期段和全周期段则是日本地区的记录最为适用。研究结果可为我国工程结构时程分析的地震动输入选取工作提供参考。Abstract: In the absence of sufficient strong-motion records from local areas, records from other countries or regions are often used as input for the dynamic time analysis of engineering structures. However, the applicability of these records to scenarios required by seismic codes has not been scientifically validated. In this study, a total of 1,697 strong-motion records from shallow crustal earthquakes in the United States, Europe, New Zealand, Japan, and Mexico, recorded over the last decade, were collected. Spectral matching was performed between the normalized response spectra of these records and the seismic design spectra specified in China’s seismic code, under the same site category conditions. The applicability of records from these regions as ground-motion inputs for engineering structural analysis in China was evaluated based on their spectral matching in both the full and partial period ranges. The following conclusions were drawn: (1) Significant regional differences in ground motion were identified through a comparison of normalized response spectra, confirming the importance of selecting local records whenever possible for ground-motion input; (2) The comparison of normalized mean spectra across near, middle, and far-field records indicated that regional differences in spectral shape are not apparent, suggesting the importance of considering site-to-source distance when selecting ground motions; (3) An evaluation process was developed based on average relative error, average coefficient of variation, and the number of records for spectral shape matching to assess the applicability of foreign strong-motion records for ground-motion input in China; (4) Optimal countries or regions for ground-motion selection for various site categories were recommended based on spectral matching across the entire period range as well as short, medium, and long periods. Specifically, records from New Zealand were found to be optimal for short-period spectral matching, while records from Japan were optimal for full-period, medium-, and long-period spectral matching. The findings of this study provide scientific guidance for selecting appropriate ground-motion input for engineering structural time analysis in China. -
表 1 备选记录按场地类别各地区分组情况
Table 1. Numbers of the strong motion records in different countries grouped with different site classes
地区 场地类别 I0 I1 II III IV 美国 6 94 440 50 0 欧洲 82 158 214 58 8 新西兰 80 50 242 178 8 日本 18 164 1060 238 62 墨西哥 0 0 30 2 0 表 2 最优推荐强震动记录的国家或地区
Table 2. Recommended countries or regions of strong motion records
周期段 场地类别 I0 I1 II III IV 全周期(0~6 s) 日本/欧洲 日本 日本 美国/日本 日本 分周期(0~0.5 s) 日本 新西兰 新西兰 新西兰 欧洲 分周期(0.5~1.5 s) 日本 日本 日本 美国 新西兰 分周期(1.5~5.5 s) 欧洲/日本 日本 欧洲 美国/日本 日本 -
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