基于SDOF体系和高层结构的地震动强度指标研究

Ground motion intensity measures based on SDOF system and high-rise structures

合理的地震动强度指标是预测和评价结构抗震响应的重要基础。选取24个周期点的单自由度体系和一个高层框架核心筒长周期结构,基于不同震源机制的100条地震动记录时程分析结果,研究16种地震动强度指标与结构地震响应的相关性,并提出考虑高阶振型影响的改进反应谱相关型地震动强度指标。研究表明:(1)不同地震动强度指标与结构地震响应的相关性差别较大,随着单自由度体系自振周期的增大,地震动强度指标与单自由度体系地震响应的相关性大致呈减小的趋势;(2)对于高层长周期结构,综合对比分析各地震动强度指标分别与顶点最大位移、最大基底剪力、最大层间位移的相关性,从工程实用角度出发,推荐地面运动峰值速度为最佳地震动强度指标;(3)由于高层长周期结构受高阶振型影响显著,采用含有高阶振型因素的反应谱强度指标可提高与结构地震响应的相关性。

Reasonable ground motion intensity measures are important basis for predicting and evaluating the seismic response of structures.One long-period high-rise frame core tube structure and a single degree of freedom(SDOF)system with 24 periodic points were selected.Based on the time-history analysis results of 100 ground motion records with different focal mechanisms,the correlations between 16 ground motion intensity measures and the structural seismic response were studied,and improved spectral correlation ground motion intensity measures considering the influence of high modes were proposed.The results showed that:(1)The correlations between different ground motion intensity measures and the structural seismic response are quite different.With the increase in natural period of SDOF system,the correlation between intensity measures and the seismic response tend to decrease.(2)According to the analysis of correlations between each intensity measure and seismic responses of the high-rise long-period structure(maximum vertex displacement,maximum base shear,and maximum story drift),the peak ground velocity is recommended as the best intensity measure for high-rise long-period structures.(3)As high-rise long-period structures are significantly affected by high modes,the response spectrum measure with high modes can be used to improve the correlation.