浅硬场地剪切波速变异性对结构地震输入的影响

The impact of shear-wave velocity variability on structural seismic input of stiff-shallow site

场地对地面结构地震动力的输入分析有决定性影响。本文用Shake 2000程序计算并讨论了浅硬场地多工况下剪切波速变化对不同周期结构动力响应的影响,主要结论如下:浅硬场地剪切波速测试标准差对地表加速度反应谱的影响很大,影响程度与输入地震动的强度、频率和剪切波速有关;剪切波速测试标准差对地表加速度反应谱的影响在大多数情况下不可忽略;对于不同周期的结构,剪切波速变化对短周期和1s周期的影响程度与地表加速度反应谱峰值略有不同;场地剪切波速减小对反应谱的影响明显大于波速增大时的影响;浅硬场地波速标准差对短周期的影响基本不可忽略,对1 s周期的影响则可以忽略;随地震动强度增加,剪切波速的减小对反应谱短周期的影响程度加大。

The sites have decisive effect on the seismic input of superstructure. This paper applies SHAKE 2000 program and discusses the impact of shear-wave velocity on the different dynamic response of periodic structure in multiple conditions of shallow-hard sites. The main conclusions are as follows ： the impact of the shear-wave velocity test standard deviation in the shallow-hard sites is great on the surface acceleration response spectra, and the degree of the influence is related to the intensity and frequency of the input ground motion and the magnitude of the shear- wave velocity ; taking the peak changes over 20% in the acceleration response spectra as the standard which cannot be ignored, the impact of the shear-wave velocity test standard deviation on the surface acceleration response spec- tra cannot be ignored in most conditions; in terms of different periodic structures, the effect degree of the changes in shear-wave velocity on the short-period and 1s-period is slightly different from peak acceleration response spec- tra; the impact of the decrease in the shear-wave velocity is significantly greater than the increase ; the impact of ve- locity standard deviation on short-cycle can＇ t be ignored, the impact on ls cycle can be ignored ; as the intensity of the motion increases, the impact of the decrease in the shear-wave velocity significantly increases.