频率对爆破地震作用下结构的动力响应的影响研究

基于结构动力学理论分析了结构在爆破地震作用下的动力响应,发现结构位移响应函数包含结构自振频率和爆破地震谐波频率因子.在此基础上提出了"频比系数"和"结构振动敏感谐波"2个概念.理论分析表明,爆破地震频率和结构自振频率对结构振动响应的影响可以综合为频比系数对结构振动响应的影响,并且这种影响是通过由于频比系数值的改变引起振幅放大系数值的变化而实现的;在所有的爆破谐波当中,结构振动敏感谐波引起的结构振动响应最大,且结构振动响应的主频与其振动敏感谐波的频率相同;在实际工程中,不仅要求显著频率段和主频要远离结构固有频率,而且还应尽可能使显著频率段的谐波频率和主频高于结构固有频率.最后,提出了将频比系数纳入爆破振动安全评估指标的构想.

Effect of Frequency on the Dynamic Response of Structure Resulting from Blasting Seism

Based on dynamics of structure,the dynamic response of structure resulting from blasting seism is analyzed.It is found that displacement function of structure includes fundamental frequency of structure and frequency of blasting seism.Two new conceptions which are the coefficient of frequency ratio and the sensitive simple-harmonic wave of vibration of structure are proposed.The analyses results show that:1) the effects of fundamental frequency of structure and frequency of blast seism on the dynamic response of structure can be regarded as the effects of the coefficient of frequency ratio on the dynamic response of structure and it is actualized through the change of the magnification coefficient of amplitude resulting from the change of the coefficient of frequency ratio;2) the dynamic response of structure resulting from sensitive simple-harmonic wave of vibration of structure is greatest and the main frequency of response of structure is the frequency of sensitive simple-harmonic wave of vibration of structure;3)the prominent frequency and the main frequency should also be higher than the fundamental frequency of structure in engineering.Finally,it is advised that the coefficient of frequency ratio become an evaluating index of safety criterion for blasting vibration.