抗震反应谱场地放大系数的研究

通过对美国西部715条水平强震观测数据分析,按照场地条件、震级、震中距3个因素分组,以Ⅱ类场地峰值加速度PGA作为地震动强度,取有效峰值加速度EPA(阻尼比为5％时,0.1～0.5s范围内加速度反应谱平均值除以2.5)作为计算标准,统计得出场地放大系数.结果表明,在同一地震强度下,Ⅰ、Ⅱ、Ⅲ场地的场地放大系数依次增大；在同一场地条件下,场地放大系数随着地震动强度的增大呈减小的趋势.在统计结果基础之上,提出了适用于我国抗震规范的场地放大系数建议值及其应用方法,可供GB 50011-2010抗震规范修订时参考.

Study on Site Amplification Coefficient of Seismic Design Response Spectrum

This paper using 715 horizontal strong earthquake records grouped according to site condition,magnitude and epicenter distance,got a group of site amplification coefficient,using peak ground acceleration of class Ⅱas earthquake ground motion intensity and the effective peak acceleration(the average of acceleration response spectrum in 0.1~0.5 s divided by 2.5 with 5% damping ration) as the calculation standard.The result shows site amplification coefficient increases with the softening of sites under the same seismic intensity;site amplification coefficient increases as the earthquake ground motion intensity strengthens in the same site.On the basis of results,it has given proposed site amplification coefficient applicable and application method for GB 50011—2010 seismic design code’s modification.