Residual displacement,as a significant measure of structural inelasticity,is effectively used in post-earthquake seismic assessment of structures.This demand can be considered for seismic evaluation of structures unde...Residual displacement,as a significant measure of structural inelasticity,is effectively used in post-earthquake seismic assessment of structures.This demand can be considered for seismic evaluation of structures under multiple earthquakes.This study introduces a simple and novel index to predict the residual displacement of mainshock-damaged structures against subsequent aftershock.The proposed index is defined as a ratio between residual displacement of damaged structures against aftershock and peak inelastic displacement of intact structures under mainshock.In this study,constantstrength spectra based on the index are developed considering the effects of important structural characteristics and also significant seismic parameters.Moreover,analytical equations are presented to predict the proposed index for bi-linear single-degree-of-freedom(SDOF)systems considering both the effects of positive and negative polarities of aftershock.Furthermore,an equation is suggested to estimate the peak inelastic displacement of intact systems under mainshock,which is required to compute the index.展开更多
In order to further deepen the understanding of seismic wave propagation characteristics induced by the large volume airgun source,experimental data from multiple fixed excitation points in Fujian Province were used t...In order to further deepen the understanding of seismic wave propagation characteristics induced by the large volume airgun source,experimental data from multiple fixed excitation points in Fujian Province were used to obtain the equivalent single excitation high signal-to-noise ratio velocity and displacement records through linear stacking and simulation techniques.Then the peak displacements of different epicentral distances were used to calculate the equivalent magnitude of the airgun source excitation at different fixed excitation points so as to establish the attenuation relationship between equivalent magnitude,epicenter distance and velocity peak.Our results show that:①Within 270 km of epicentral distance,for the large-volume airgun’s single shot,the peak velocity range is about 700-4 nm/s,and the peak displacement range is about 200.0-0.2 nm;②The equivalent magnitude of the P-wave from the airgun source with a total capacity of 8,000 in 3 is 0.181-0.760,and the equivalent magnitude of the S-wave is 0.294-0.832.By contrast,the equivalent magnitude of the P-wave from the airgun source with a total capacity of 12,000 in 3 is 0.533-0.896,and the equivalent magnitude of the S-wave is 0.611-0.946.The S-wave energy is greater than the P-wave energy,and the excitation efficiency varies greatly with different excitation environment;③The peak velocity increases with the equivalent magnitude,and decreases with the epicentral distance.The vertical component of the P-wave peak velocity is the largest among those three components,while the S-wave has the smallest vertical component and similar horizontal components.Hence,our research can provide an important basis for the quantitative judgment of the seismic wave propagation distance using the airgun and the design of the observation system in deep exploration or monitoring with airgun.展开更多
文摘Residual displacement,as a significant measure of structural inelasticity,is effectively used in post-earthquake seismic assessment of structures.This demand can be considered for seismic evaluation of structures under multiple earthquakes.This study introduces a simple and novel index to predict the residual displacement of mainshock-damaged structures against subsequent aftershock.The proposed index is defined as a ratio between residual displacement of damaged structures against aftershock and peak inelastic displacement of intact structures under mainshock.In this study,constantstrength spectra based on the index are developed considering the effects of important structural characteristics and also significant seismic parameters.Moreover,analytical equations are presented to predict the proposed index for bi-linear single-degree-of-freedom(SDOF)systems considering both the effects of positive and negative polarities of aftershock.Furthermore,an equation is suggested to estimate the peak inelastic displacement of intact systems under mainshock,which is required to compute the index.
基金the National Natural Science Foundation of China(41790461)
文摘In order to further deepen the understanding of seismic wave propagation characteristics induced by the large volume airgun source,experimental data from multiple fixed excitation points in Fujian Province were used to obtain the equivalent single excitation high signal-to-noise ratio velocity and displacement records through linear stacking and simulation techniques.Then the peak displacements of different epicentral distances were used to calculate the equivalent magnitude of the airgun source excitation at different fixed excitation points so as to establish the attenuation relationship between equivalent magnitude,epicenter distance and velocity peak.Our results show that:①Within 270 km of epicentral distance,for the large-volume airgun’s single shot,the peak velocity range is about 700-4 nm/s,and the peak displacement range is about 200.0-0.2 nm;②The equivalent magnitude of the P-wave from the airgun source with a total capacity of 8,000 in 3 is 0.181-0.760,and the equivalent magnitude of the S-wave is 0.294-0.832.By contrast,the equivalent magnitude of the P-wave from the airgun source with a total capacity of 12,000 in 3 is 0.533-0.896,and the equivalent magnitude of the S-wave is 0.611-0.946.The S-wave energy is greater than the P-wave energy,and the excitation efficiency varies greatly with different excitation environment;③The peak velocity increases with the equivalent magnitude,and decreases with the epicentral distance.The vertical component of the P-wave peak velocity is the largest among those three components,while the S-wave has the smallest vertical component and similar horizontal components.Hence,our research can provide an important basis for the quantitative judgment of the seismic wave propagation distance using the airgun and the design of the observation system in deep exploration or monitoring with airgun.
