【摘要】 为了从能量角度研究重力坝地震响应的时频特征,在重力坝非线性动力分析基础上,探讨了重力坝地震过程中振动能量的时域耗散机制;采用小波频域多层次分解技术研究了其动响应的分频段能量特征,得到了坝体典型位置动响应分频段振动能量随高程的变化规律。通过分析发现:结构地震能量耗散为时域上不可逆的增加,坝体损伤集中出现在地震过程的某个时间段,地震动峰值后坝体损伤状态基本稳定;小波分解可以较全面地描述结构动响应能量的分频段特征。对于本文算例,在坝踵和上游折坡附近,重力坝地震响应的振动能量以4～8 Hz频段为主,这与输入的地震信号分频段特征一致;而坝顶附近则以1～4 Hz的振动能量为主,高频能量分量的比重随高程增大而逐渐减小。更多还原

【Abstract】 Aiming at the time-frequency characteristic research of the gravity dam via the energy viewpoint,the energy dissipation mechanism is studied for the earthquake responses of the dams based on their nonlinear seismic performance during the whole process of vibration;Wavelet analysis is made for the distinct frequency characteristics of vibration energy of the typical dam position with the change of elevations.Analysis results show that during the earthquake,the energy dissipation is increasing,Damage to the dams appears in a certain time period and the status is stable after the peak time;frequency characteristics of seismic responses of the dams can be clearly revealed by wavelet decomposition technique.For the example in this paper,the major influential frequency band of the response energy is obtained as 4 ～ 8 Hz for the dam heel and the fold slope point of the upstream,which is consistent with the energy distributions of the input Koyna signal in distinct frequency channel,meanwhile,the major frequency band is 1 ～ 4 Hz for the dam crest and the high frequency components have minor effects along with the increase of elevation.更多还原