【作者】 刘毅；

【导师】 杨迪雄；

【作者基本信息】 大连理工大学 ， 工程力学， 2012， 硕士

【摘要】 在地震工程界,近断层地震动对人类环境的破坏及其独特的工程特性对结构物抗震性能和减震控制的影响是学者们备受瞩目的研究课题。本文选取了台湾集集地震与美国北岭地震的地震动记录作为研究对象,利用单自由度(SDOF)系统对近断层地震动的需求谱(包括强度折减系数谱、位移比谱、能量谱)进行了系统的分析,并且利用相关性分析研究了近断层地震动的持时效应。首先对所选取的150条集集和北岭地震动记录进行有、无速度脉冲的运动特征分类。选用单自由度系统(SDOF系统)双线性滞回模型,不考虑模型的刚度与强度的退化,分析了延性系数、阻尼比、结构弹性周期对强度折减系数谱、位移比谱的影响。计算结果表明：在短周期和中周期段,延性系数与自振周期对平均强度折减系数谱、位移比谱的影响较大；长周期段,阻尼比、延性系数和自振周期对平均强度折减系数谱、位移比谱基本没有影响。脉冲、无脉冲地震动的强度折减系数谱和位移比谱差别不大。其次,分析了延性系数、阻尼比、结构弹性周期对输入能谱、滞回耗能谱、能量比谱以及等效速度谱的影响。结果表明：近断层地震动的脉冲特性对SDOF体系的平均输入能量谱EI和平均能量比谱EH/EI的大小和形状影响明显。体系延性系数、阻尼比、自振周期是影响双线性SDOF体系能量谱的重要因素。并且,集集地震和北岭地震两次地震事件的近断层地震动的平均输入能量谱EI和平均能量比谱EH/EI差别较大。最后,研究了地震动强度参数与地震动持时之间的相关性,地震动强度参数、持时与结构反应的相关性,结合脉冲型近断层地震动的特点提出了与地震动速度有关的持时参数。研究结果表明：加速度绝对一致持时与和地震动加速度有关的强度参数相关性较大,速度绝对一致持时与地震动速度和位移相关的强度参数相关性较大。强度参数与结构反应的相关性和周期段有很大联系,结构反应在短周期内(加速度敏感区)和加速度相关的强度参数相关性大,在中周期与中长周期内(速度敏感区)和速度相关的强度参数相关性较大,在长周期内(位移敏感区)与位移相关的强度参数的相关性很大。另外,在短周期段,加速度绝对一致持时与结构反应的相关性很好,无脉冲地震动的持时参数与结构反应具有较好的负相关性；在中长周期段,速度绝对一致持时与结构反应的相关性好。更多还原

【Abstract】 In the field of earthquake engineering, near-fault ground motions are the research topocis of interest to the researchers for their destruction to human environment and their unique engineering characteristics which affect the seismic performance and vibration mitigation of structures. In the present paper, the ground motions records of Taiwan Chi-Chi earthquake and the Northbridge earthquake are selected as input. The demand spectra (including strength reduction factor spectra, displacement ratio spectra and energy spectra) of near-fault ground motions are analyzed systematically of Single Degree Of Freedom (SDOF) system. Moreover, the duration effect of near-fault ground motions is also studied by means of correlation analysis.Firstly, the150Chi-Chi and Northbridge earthquake records are classified according to their motion characteristics with and without velocity pulse. Using the bilinear hysteresis model of SDOF system without considering the degradation of stifiness and strength, the effects of ductility factor, damping ratio and structural elastic period on the strength reduction factor spectra, displacement ratio spectra are analyzed. Numerical results indicate that, in the short and medium period range, the ductility factor and natural period present the great influence on the mean strength reduction factor spectra and displacement ratio spectra; in the long period range, the ductility factor and natural period basically have no effect on mean strength reduction factor spectra and displacement ratio spectra. In addition, the difference of the two demand spectra for impulsive and non-pulse near-fault ground records is not large.Secondly, the effects of ductility factor, damping ratio and structural elastic period on input energy spectra, hysteresis energy dissipation spectra, energy ratio spectra and equivalent velocity spectra are examined. The calculated results demonstrate that the distinct pulse of near-fault ground motions impose remarkable effects on the peak and shape of mean input energy spectra EI and energy ratio spectra EH/EI. Moreover, the ductility level, damping ratio and natural period of systems produce important effects on the energy spectra of bilinear SDOF systems, and the effect of yield stiffness ratio can be neglected. The mean input energy spectra EI and energy ratio spectra EH/EI are fairly different for the two different earthquake events such as the Chi-Chi and Northridge earthquake.Finally, the correlation analysis between intensity measures and duration of near-fault ground motions, as well as the correlation between intensity parameters and duration of ground motions and structural response are explored. Meanwhile, combining the property of pulse-like near-fault gorund motions the velocity based duration parameters of ground motions are proposed. It is shown that, the acceleration based absolute uniform duration has high correlation with acceleration related intensity measure parameters; velocity based absolute uniform duration presents strongcorrelation with the velocity and displacement related intensityindices. Meanwhile, the natural periods of SDOF systems significantly affect the correlation between intensity parameters and structural responses. Furthermore, the structural responses have high correlation with acceleration related intensity parameters in the short period region (acceleration sensitive region); and they are strongly correlated with velocity related intensity parameters in the medium and long period region (velocity sensitive region) and with displacement related strength parameters in the long period region,(displacement sensitiveregion). Additionally, in the short period region, the acceleration based absolute uniform duration has good correlation with structural responses, the duration parameters of non-pulse ground motions have strong negative correlation with structural responses. In the medium and long period region, the velocity based absolute uniform duration is well correlated with structural responses.更多还原