考虑上下盘效应的Newmark设计谱

以全球典型倾滑断层的近断层强震记录为依据,分析上/下盘效应对核电厂抗震设计谱的影响,为构建考虑近断层上/下盘效应的核电厂设计谱提供参考.基于上/下盘不同区域的近断层记录,分析Newmark方法中地震动峰值比控制参数AD/V²、V/A的取值,发现核电厂抗震设计谱的拐点周期随着强震记录的特点而改变,且AD/V²、V/A的取值受到上/下盘效应的影响.上盘记录的V/A值小于其它区域,而AD/V²值则大于其它区域.由于AD/V²与V/A的值决定了设计谱第三、第四个控制点周期,因此设计谱的谱形也受到影响.通过对比本次确定的设计谱与RG1.60设计谱,发现上/下盘效应对设计谱短周期段的谱值有显著的影响.这使得短周期段谱值增大,而对中长周期段的影响不明显.无论是设计谱的形状还是谱值大小,基岩场地设计谱的变化比土层场地的大.由此可见,在编制标准反应谱时建议考虑上/下盘效应的影响.

Newmark design spectrum considering hanging wall and footwall effect

Based on records of the near-fault strong earthquake of the typical slip fault in the world, the effects of hanging wall / foot wall on a seismic design spectrum of a nuclear power plant is analyzed, and a reference is provided, it is for constructing the design spectrum of the nuclear power plant which counts in effects of hanging wall / foot wall of the near-fault is provided. Based on the near fault records of distinct areas of the hanging wall / foot wall, values of control parameters AD/V² and V/A for the peak ground motion ratio in Newmark method are analyzed. It is found that a inflexion period of seismic design spectrum of the nuclear power plant changes with characteristics of strong earthquake records, and the values of AD/V² and V/A are affected by the hanging wall / foot wall effect. The V/A value associated with the hanging wall is smaller than that in other areas, while theAD/V² value is bigger than that in other areas. Since the values of AD/V² and V/A determine periods of the third and fourth control point of the designed spectrum, the shape of the designed spectrum is also affected. By comparing the determined design spectrum with RG1.60 design spectrum, it is found that the hanging wall / foot wall effect has a significant impact on the spectral values within the short period of the designed spectrum, which makes the spectral values within the short period increase,while the impact on the medium / long period is not evident. Whether either the shape or the values of the designed spectrum, the change of the designed spectrum of the bedrock site is greater than that of design spectrum of soil site. It can be seen therefore that the influence of the hanging wall / foot wall effect should be taken into account in future preparation of standard response spectrum.