适用于全周期结构的速度脉冲型地震动强度表征参数研究

Intensity measures of pulse-like ground motions in the full periods

鉴于传统的地震动强度表征参数(IM)不能有效地反映速度脉冲型地震动的破坏特征,需要研究能够在全周期段内表征速度脉冲型地震动强度的参数。本文首先从NGA-West2强震数据库中选取了236条速度脉冲记录,分析了42种地震动参数之间的相似性和相关性,初步给出了速度脉冲型地震动强度的表征参数;其次,利用单自由度体系动力时程分析方法,研究了不同延性μ条件下速度脉冲型地震动强度表征参数与最大非线性位移um之间的相关性系数随周期T的变化特征,并通过线性回归和离差分析方法确定了初步给出的速度脉冲型地震动强度表征参数的有效性及其应用范围;最后,将速度脉冲对加速度反应谱的放大系数Af作为速度脉冲型地震动强度表征参数,并验证其有效性。结果表明:(1)当0<T<1 s时,Sa(T)作为速度脉冲型地震动强度表征参数的有效性较好;(2)当1<T<3 s时,Sa,avg,Sv,avg,PPV,If和PGV作为速度脉冲型地震动强度表征参数的有效性较好;(3)当3<T<6 s时,Sa,avg,Sv,avg,PPV,If,PGV和Sa(T)不宜作为速度脉冲型地震动强度表征参数;(4)当0<T<6 s时,Af作为速度脉冲型地震动强度表征参数的有效性较好,而且,当结构自振周期小于速度脉冲周期时,Af作为速度脉冲型地震动强度表征参数时um的离散性最小。

Since the traditional ground motion intensity measure(IM)cannot reflect the destructive characteristic of the pulse-like ground motion effectively,thus it is crucial to study the pulse-like ground motion’s IM in full periods.In this paper,236 pulse-like records were selected from the NGA-West2 database,and the similarities and correlativities among the 42 ground motion parameters were studied;meanwhile,the intensity measures of pulse-like ground motion were preliminary confirmed.Secondly,based on the analysis of the dynamic timehistory of the single-degree-of-freedom system,the variation features of correlation coefficients between the pulse-like ground motion’s IM and the maximum nonlinear displacement um with period were studied under different ductilityμconditions.The validity of predetermined pulselike ground motion’s IM were determined by the linear regression and dispersion analysis.Finally,the acceleration response spectrum amplification factor Af was proposed to be the IM parameter considering pulse-like non-station arity,and its validity was further verified.The results show that:①Sa(T)was more suited to be the IM in the period 0-1 s;②Sa,avg,Sv,avg,PPV,If and PGV are more suitable as IM than Sa(T)in the period 1-3 s;③Sa,avg,Sv,avg,PPV,If,PGV and Sa(T)are not appropriate to be IM in the period 3-6 s;④Af is more specifically suitable to be the parameter of pulse-like ground motion’s IM in the period 0-6 s.And when the natural vibration period of the structure was less than pulse-like period,um has the minimum dispersion with the Af as the IM.