近断层地震各因素对基础隔震结构的影响

Effect of Characteristics of Near-fault Ground Motions on Isolated Buildings

系统地分析了场地土、近断层地震的频谱、加速度峰值、脉冲周期等因素对基础隔震结构的影响。采用不同场地下的实际近断层地震波,计算了一个多层隔震结构的各项能量响应,并与远场地震下的情况进行对比,结果发现,场地土会影响地震波频谱,在硬场及中等场地下,近断层地震包含较多的长周期频谱,但这一特征在软场情况下并不明显,因此,在硬场和中等场地下,近断层地震较远场地震对隔震结构更为不利,而在软场下,远场地震对隔震结构更不利;近断层地震的加速度峰值不是影响隔震结构位移的主要因素,隔震结构的最大变形由地震瞬时输入能量决定;脉冲周期对隔震结构影响不大,应调整结构的自振周期以改善减震效果。

A detailed and systematic investigation on the performance of isolated buildings subject to near-fault motions is introduced in this paper. Energy analysis of an actual multi-stories isolated building is calculated under a number of real near-fault motions with various frequency spectra, ground types, peak accelerations and pulse periods. The following conclusions are attained, （1） Ground type have effect on the frequency spectra of near-fault motions. On rigid ground and medium ground, the high frequency is in the majority under near-fault motions, which is not good for isolated buildings, whereas no same happen to the soft ground. （2） The peak acceleration is not responsible for the displacement of isolated buildings. The instantaneous input energy of isolated buildings lead to the maximum displacement of isolated buildings. （3） The effect of pulse period on isolated buildings is not prominent. Therefore, the increase of structural periods will improve performance of isolate buildings.