SEISMIC-FORCE-MODIFICATION FACTOR FOR STRUCTURES WITH BILINEAR ELASTOPLASTIC MODEL
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摘要: 对双折线弹塑性滞回模型的单自由度体系在地震作用下的响应进行了分析，得到了不同场地、结构自振周期、延性、阻尼比、后期刚度系数等参数组合下的结构影响系数R。结果表明：R谱的决定性因素是结构的延性，延性越大R越大；阻尼比、后期刚度对R的影响是第二位的，而阻尼只在短周期范围内有比较明显的影响。对场地特征周期用六种不同的方法进行了分析，取五种分析结果一致的特征周期，对R谱的横轴标准化，得到的R谱保留了在Tg处的峰值特征。对各周期和延性下的R进行统计分析，发现其符合对数正态分布，并提出了延性影响系数Rμ的计算公式。
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关键词:
- 抗震设计 /
- 结构影响系数 /
- 双折线弹塑性滞回模型 /
- 延性 /
- 场地特征周期
Abstract: Based on elastic-plastic time-history earthquake analysis of the single degree of freedom (SDOF) system, the seismic-force-modification factor R of the bilinear elastic-plastic model was investigated for different site types, natural vibration periods, ductility, damping ratios and post-yield stiffness ratios. It is found that the most important factor determining R is the ductility, and that damping and the post yield stiffness have only a minor effect in the short period range. In the long period range, the damping has negligible effect on R spectra. The characteristic period Tg of the site was analyzed using six different approaches, among which five methods get the identical Tg. This Tg was used to normalize R spectra to maintain the peak phenomena near Tg. The probability distribution of R factor appears to be consistent with the lognormal distribution. Simplified formulae are proposed for Rμ spectra. -
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