Classification Assessment Of The Destructive Power Of Near-fault Pulse-like Ground Motions

The impact effect of pulse-like ground motion will cause severe damage to the structure,and the destructive power of different pulse-like ground motions still has great differences.Quantitative identification of pulse-like ground motions and further quantitative and hierarchical evaluation of the damage of pulse-like ground motions are essential prerequisites for improving the reliability of seismic design and calculation based on pulse-like ground motions.This paper aims to review and summarize the relevant research on the quantitative identification of pulse-like ground motions and quantitatively evaluate the destructive power of pulse-like ground motions.This paper reviews and analyzes the similarities and differences of related calculation methods from three aspects: the strongest direction of the pulse,the pulse period,and the quantitative identification of the pulse-like ground motion.Based on the recognition results of pulse-like ground motions and guided by the seismic responses of four multi-layered reinforced concrete structure models,a mapping model between the wavelet time-frequency map of pulsed ground motions and the destructive force level was established combined with convolutional neural networks.The model can predict the destructive force of pulse-like ground motions after training.The destructive force classification results based on one-directional ground motion and bi-directional ground motion input are compared and analyzed through directional research.(1)When the wavelet coefficient is used as the index to determine the pulse direction,the vertical component of ground motion has no significant effect on the results.PPV(Peak-to-Peak Velocity)maximum direction,maximum wavelet coefficient direction,PGV(Peak Ground Velocity)maximum direction,and maximum energy direction are all close.And their corresponding PGV and PPV are also similar,respectively.It is not necessarily accurate to use the fault-normal direction of fault as the most substantial pulse direction.(2)The pulse periods obtained using different peak points of the response spectrum are usually relatively close.For pulse-like ground motions with a short period,whether the vertical component is considered has less influence on the calculation results of the pulse period.Quantitative identification methods of pulse-like ground motion can be divided into two categories: time-frequency domain analysis and time-domain analysis.(3)Considering the accuracy and loss value of the model comprehensively,the optimal setting value of network model parameters is obtained,and the model accuracy can be as high as 96% or more.After the appropriate model parameters are determined,the wavelet time-frequency diagram of the ground motion can be directly input to classify the destructive force of the pulse-like ground motion.(4)Different angles of pulse-like ground motion will lead to significant differences in the damage degree of the structure.Therefore,it is recommended to consider the influence of the ground motion incident angle in the seismic design of the structure.(5)When the ground motion input is one-directional and bi-directional,the classification results of most of the pulse-like ground motion damage are consistent.However,the classification of one-directional ground motion may be lower than the actual bi-directional ground motion for some ground motions.