抗震设计反应谱的动力放大系数

我国现行抗震设计规范（GB50011-2010）动力放大系数βmax值为2．25，且βmax取值只考虑了场地因素，未考虑震级、震中距的影响。本文利用美国西部726条水平强震记录，从场地、震级、震中距三因素入手，考虑单一因素和多因素不同组合对βmax的影响。结果表明，考虑不同因素，统计结果有一定的差异，而仅考虑场地因素时，统计结果与目前规范取值非常接近。综合考虑各种组合情况，考虑场地、震中距、震级因素组合更能代表目前地震动的认识水平。在统计结果基础之上，建议βmax取值为2．50。

Dynamic Amplification Coefficient of Seismic Design Response Spectrum

The value of dynamic amplification coefficient in current Chinese seismic design code （GBS0011- 2010） is 2.25. It considers only the effect of the site condition, no magnitude and epicenter distance. With 726 strong earthquake records from the west of the Unites States, the dynamic amplification coefficient is studied as a single factor and multi-factor considering the effects of site condition, magnitude and epicenter distance. The results show that dynamic amplification The result from the effect of site condition is very close coefficient has great differences under various factors. to the value of current Chinese seismic design code. To sum up, the group of site condition, magnitude and epicenter distance is more representative of the level for understanding seismic ground motion. Based on the statistical results, the proposed value of dynamic amplification coefficient is 2.5.