位移谱阻尼调整系数模型研究

基于408条地震地面运动记录的统计分析,首先研究了地震动持时、矩震级、断层距和场地类别等对阻尼调整系数的影响,然后采用非线性回归分析提出了能体现持时和矩震级影响的阻尼调整系数模型.研究结果表明:持时和矩震级对阻尼调整系数有显著的影响,而断层距和场地类别影响较弱;阻尼调整系数相对于阻尼比存在异方差性;持时的影响可以通过在模型中包含线性震级项来体现.本文所提出的包含线性矩震级项的阻尼调整系数模型既能体现矩震级的影响,也能间接地体现地震动持时对阻尼调整系数的影响;模型的标准差能体现阻尼调整系数相对于阻尼比的异方差性.本文的研究结果可直接用于阻尼比为5%的位移谱衰减模型,也可为我国抗震设计规范的制订和修改提供参考.

Study on Damping Scaling Factor Model for Displacement Response Spectra

Dependencies of the damping scaling factor (DSF) on variables 1including duration, moment magnitude, fault distance, and local site conditions were examined from 408 acceleration time histories. Then the DSF model was derived 2that can be used to capture the influence of duration and moment magnitude. It is shown that the influence of 3duration and moment magnitude on DSF is significant, but that of 4fault distance and local site conditions is weak. Furthermore, the DSF is heteroscedastic, where the variance is a function of the damping ratio. The significant influence of 5duration and moment magnitude can be captured by inclusion of a linear magnitude term in the DSF model. The heteroscedasticity can be reflected in the standard deviation of the DSF model. The results can be directly applicable to the attenuation model for displacement response spectra of 5% damping ratio and can also provide the reference for the revisions of seismic design codes.