初始条件不相容地震动加速度信号的基线校正算法

An Algorithm for Baseline Correction of Seismic Signals with Incompatible Initial Conditions

将地震加速度信号积分为速度、位移时程,或使用其进行地震响应分析时通常假定初始速度、位移为零,不满足这一假定被称为初始条件不相容。针对人为截断后的加速度信号由于初始条件不相容造成的速度和位移时程的基线偏移的问题,提出了一种简单有效的基线校正方法。从理论上解释了初始条件不相容导致基线偏移的原因。从整体偏移和局部偏移的角度定义了评价基线偏移程度的两个指标,即基线偏移比(DR)和幅值比(AR)。通过在趋势多项式中考虑速度和位移时程的零初值及其基线偏移趋势,改进了加速度信号基线校正方法。以一个地震地面运动记录为例,对所提方法进行了验证。结果表明:相比传统的仅考虑加速度时程的基线校正方法,改进方法能够在保证速度和位移时程的地面运动一般初值条件的前提下,更加准确高效地实现加速度信号的基线校正。

When the seismic acceleration signal is integrated to obtain the velocity and displacement history, or utilized in seismic response analysis, generally the initial velocity and displacement are assumed as zero. Theassumed initial conditions that are not met are referred to as incompatible initial conditions. Aimed at the baseline shifting problem occurring in the velocity and displacement histories due to the incompatible initial conditions, which is caused by artificially truncated acceleration signals, a simple and effective baseline correction method is proposed. Cause of the baseline shifting due to the incompatible initial conditions, is theoretically discussed. Two indicators measuring level of the baseline shifting, termed baseline drifting ratio（ DR） and amplitude ratio（ AR）, are defined from the viewpoint of overall drifting and local shifting,respectively. By including zero initial conditions and baseline shifting trends of the velocity and displacement histories in the trend polynomial, the traditional baseline correction method of acceleration signal is improved. A seismic ground motion record is utilized as an example to verify the proposed method. It is found that comparing with the traditional baseline correction method, in which acceleration history is only considered, the proposed method can achieve more accurate and efficient baseline correction, and guarantee consistence of the velocity and displacement initial conditions with the common convention of ground motions at the same time.