近场强震动记录基线校正方法的振动台实验研究

Analysis on Baseline Correction Method of Strong Motion Accelerogram Recorded on Near-fault Site by the Shaking Table Test

为了获取近场永久位移,通常采用基线校正方法,对近场加速度记录进行基线校正并积分得到永久位移值,但这一结果主观性较强,其可靠性也往往缺乏验证。为了解决这一问题,本文提出了一种能产生包含永久位移振动过程的振动台实验方案,采用振动台加滑动机构的方法,模拟记录到永久位移台站测点的真实振动情况;在实验中分别采用加速度计、摄影测量方法分别直接得到加速度和位移时程,对加速度时程进行基线校正并积分得到位移时程,将其与直接获得的位移时程进行对比,以验证采用基线校正方法的有效性。实验结果表明,在实验室条件下采用现有的基线校正方法校正后,通过积分能得到可以接受的位移时程。

For determining the near-fault site permanent displacement in some specialized methods, near-fault accelerogram was corrected with baseline, and integrated into the displacement time history. The above result is often of uncertain and even not easy to be validated because of using the subjective parameters in process. To solve this problem, we proposed a shaking table test scheme to simulate the shake process including the permanent displacement. In the test, a system comprising the shaking table and the specialized sliding mechanism were used to model the actual shake situation on the site recorded the permanent displacement. The accelerogram was recorded by the accelerometer on the sliding mechanism, and the actual displacement time history was achieved on close-range photogrammetry. The displacement integrated by the aecelerogram corrected the baseline was compared with the actual displacement to prove the reliability of the correction method. Our results show that the accelerogram could be integrated to the reliable displacement time history under the laboratory condition, after the baseline corrected with the specialized method.