Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spect~＇a, even if the diagrams recorded at the site in question. In orde...Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spect~＇a, even if the diagrams recorded at the site in question. In order to design earthquake resistant structures, we, instead, suggest constructing a design spectrum using a set of spectra that have common characteristics to the recorded acceleration diagrams at a particular site and smoothing the associated data. In this study, we conducted a time history analysis and determined a design spectrum for the region near the Lali tunnel in Southwestern Iran. We selected 13 specific ground motion records from the rock site to construct the design spectrum. To process the data, we first applied a base-line correction and then calculated the signal-to-noise ratio （]~SN） for each record. Next, we calculated the Fourier amplitude spectra of the acceleration pertaining to the signal window （1）, and the Fourier amplitude spectra of the associated noise （2）. After dividing each spectra by the square root of the selected window interval, they were divided by each other （1 divided by 2）, in order to obtain the ~SN ratio （filtering was also applied）. In addition, all data were normalized to the peak ground acceleration （PGA）. Next, the normalized vertical and horizontal responses and mean response spectrum （50%） and the mean plus-one standard deviation （84%） were calculated for all the selected ground motion records at 5% damping. Finally, the mean design spectrum and the mean plus-one standard deviation were plotted for the spectrums. The equation of the mean and the above-mean design spectrum at the Lali tunnel site are also provided, along with our observed conclusions.展开更多
Ground-motion Intensity Measures (IMs) are used to quantify the strength of ground motions and evaluate the response of structures. IMs act as a link between seismic demand and seismic hazard analysis and therefore, h...Ground-motion Intensity Measures (IMs) are used to quantify the strength of ground motions and evaluate the response of structures. IMs act as a link between seismic demand and seismic hazard analysis and therefore, have a key role in performance-based earthquake engineering. Many studies have been carried out on the determination of suitable IMs in terms of effi ciency, suffi ciency and scaling robustness. The majority of these investigations focused on ordinary structures such as buildings and bridges, and only a few were about buried pipelines. In the current study, the optimal IMs for predicting the seismic demand of continuous buried steel pipelines under near-fi eld pulse-like ground motion records is investigated. Incremental dynamic analysis is performed using twenty ground motion records. Using the results of the regression analysis, the optimality of 23 potential IMs are studied. It is concluded that specifi c energy density (SED) followed by VSI[ω1(PGD+RMSd )] are the optimal IMs based on effi ciency, suffi ciency and scaling robustness for seismic response evaluation of buried pipelines under near-fi eld ground motions.展开更多
The great Ms8.0 Wenchuan earthquake has been the most destructive earthquake since 1949 in China. The earthquake occurred no more than half a year after the establishment of the National Strong Motion Observation Netw...The great Ms8.0 Wenchuan earthquake has been the most destructive earthquake since 1949 in China. The earthquake occurred no more than half a year after the establishment of the National Strong Motion Observation Network System （NSMONS） of China; what is more, the epicenter was located in the area with dense strong motion observation sta- tions so that a large number of strong motion records of the main shock were obtained. In this paper, 501 strong motion re- cords from 167 observation stations are utilized to establish the ground motion attenuation relations in three directions in the range of fault distance less than 600 km. The result shows the difference of seismic motion attenuation in two horizontal di- rections is insignificant. It is the first time that strong-motion records are used to establish the ground motion attenuation relations of the Ms8.0 earthquake in China.展开更多
This paper proposes that on the basis of near-source saturation characteristic of ground motion, the peak ground motion acceleration and the acceleration response spectra of diffuse earthquakes affecting the nuclear f...This paper proposes that on the basis of near-source saturation characteristic of ground motion, the peak ground motion acceleration and the acceleration response spectra of diffuse earthquakes affecting the nuclear facility site can be determined by the statistic method. In view of the problem of insufficient statistic samples due to fewer qualified strong earth- quake records on the bedrock site, it also proposes that according to the features of ground motion response of the soil, the acceleration records on the soil site can be transformed into the equivalent acceleration records on rock site for a simultane- ous statistic analysis together with the records on rock site. Consequently, we have obtained by this method the near-source peak acceleration and the acceleration response spectra of small and moderate earthquakes on the site that could meet the need of nuclear facility and made a comparative analysis to the results from relevant researches. This new method for deter- mining diffuse earthquakes is only preliminarily verified in the paper and further research is needed for practical application.展开更多
The catalogs of ground motion parameters for earthquake-prone regions of Kazakhstan used for modeling seismic effects in seismic hazard assessment and microzonation are presented.
Joint inversion of teleseismic body-wave data and strong ground motion waveforms was applied to determine the rupture process of the 2010 Mentawai earthquake. To obtain stable solutions, smoothing and non-negative con...Joint inversion of teleseismic body-wave data and strong ground motion waveforms was applied to determine the rupture process of the 2010 Mentawai earthquake. To obtain stable solutions, smoothing and non-negative constraints were introduced. A total of 33 teleseismic stations and 5 strong ground motion stations supplied data. The teleseismic and strong ground motion data were separately windowed for 150 s and 250 s and bandpass filtered with frequencies of 0.001e1.0 Hz and 0.005e0.5 Hz, respectively. The finitefault model was established with length and width of 190 km and 70 km, and the initial seismic source parameters were set by referring to centroid moment tensor(CMT) solutions. Joint inversion results indicate that the focal mechanism of this earthquake is thrust fault type, and the strike, dip, and rake angles are generally in accordance with CMT results. The seismic moment was determined as 5.814 1020Nm(Mw7.8) and source duration was about 102 s, which is greater than those of other earthquakes of similar magnitude. The rupture nucleated near the hypocenter and then propagated along the strike direction to the northwest, with a maximum slip of 3.9 m. Large uncertainties regarding the amount of slip retrieved using different inversion methods still exist; however, the conclusion that the majority of slip occurred far from the islands at very shallow depths was found to be robust. The 2010 Mentawai earthquake was categorized as a tsunami earthquake because of the long rupture duration and the generation of a tsunami much larger than was expected for an earthquake of its magnitude.展开更多
文摘Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spect~＇a, even if the diagrams recorded at the site in question. In order to design earthquake resistant structures, we, instead, suggest constructing a design spectrum using a set of spectra that have common characteristics to the recorded acceleration diagrams at a particular site and smoothing the associated data. In this study, we conducted a time history analysis and determined a design spectrum for the region near the Lali tunnel in Southwestern Iran. We selected 13 specific ground motion records from the rock site to construct the design spectrum. To process the data, we first applied a base-line correction and then calculated the signal-to-noise ratio （]~SN） for each record. Next, we calculated the Fourier amplitude spectra of the acceleration pertaining to the signal window （1）, and the Fourier amplitude spectra of the associated noise （2）. After dividing each spectra by the square root of the selected window interval, they were divided by each other （1 divided by 2）, in order to obtain the ~SN ratio （filtering was also applied）. In addition, all data were normalized to the peak ground acceleration （PGA）. Next, the normalized vertical and horizontal responses and mean response spectrum （50%） and the mean plus-one standard deviation （84%） were calculated for all the selected ground motion records at 5% damping. Finally, the mean design spectrum and the mean plus-one standard deviation were plotted for the spectrums. The equation of the mean and the above-mean design spectrum at the Lali tunnel site are also provided, along with our observed conclusions.
文摘Ground-motion Intensity Measures (IMs) are used to quantify the strength of ground motions and evaluate the response of structures. IMs act as a link between seismic demand and seismic hazard analysis and therefore, have a key role in performance-based earthquake engineering. Many studies have been carried out on the determination of suitable IMs in terms of effi ciency, suffi ciency and scaling robustness. The majority of these investigations focused on ordinary structures such as buildings and bridges, and only a few were about buried pipelines. In the current study, the optimal IMs for predicting the seismic demand of continuous buried steel pipelines under near-fi eld pulse-like ground motion records is investigated. Incremental dynamic analysis is performed using twenty ground motion records. Using the results of the regression analysis, the optimality of 23 potential IMs are studied. It is concluded that specifi c energy density (SED) followed by VSI[ω1(PGD+RMSd )] are the optimal IMs based on effi ciency, suffi ciency and scaling robustness for seismic response evaluation of buried pipelines under near-fi eld ground motions.
基金supported by Earthquake Research Foundation of China Earthquake Administration (No. C08043)Social Development Plan Foundation of Yunnan Province (2007CA002)
文摘The great Ms8.0 Wenchuan earthquake has been the most destructive earthquake since 1949 in China. The earthquake occurred no more than half a year after the establishment of the National Strong Motion Observation Network System （NSMONS） of China; what is more, the epicenter was located in the area with dense strong motion observation sta- tions so that a large number of strong motion records of the main shock were obtained. In this paper, 501 strong motion re- cords from 167 observation stations are utilized to establish the ground motion attenuation relations in three directions in the range of fault distance less than 600 km. The result shows the difference of seismic motion attenuation in two horizontal di- rections is insignificant. It is the first time that strong-motion records are used to establish the ground motion attenuation relations of the Ms8.0 earthquake in China.
基金supported by the Special Funds for Sciences and Technology Research (No. 200708003 and No. 200808008)National Natural Science Foundation of China (No. 90715020)
文摘This paper proposes that on the basis of near-source saturation characteristic of ground motion, the peak ground motion acceleration and the acceleration response spectra of diffuse earthquakes affecting the nuclear facility site can be determined by the statistic method. In view of the problem of insufficient statistic samples due to fewer qualified strong earth- quake records on the bedrock site, it also proposes that according to the features of ground motion response of the soil, the acceleration records on the soil site can be transformed into the equivalent acceleration records on rock site for a simultane- ous statistic analysis together with the records on rock site. Consequently, we have obtained by this method the near-source peak acceleration and the acceleration response spectra of small and moderate earthquakes on the site that could meet the need of nuclear facility and made a comparative analysis to the results from relevant researches. This new method for deter- mining diffuse earthquakes is only preliminarily verified in the paper and further research is needed for practical application.
文摘The catalogs of ground motion parameters for earthquake-prone regions of Kazakhstan used for modeling seismic effects in seismic hazard assessment and microzonation are presented.
基金supported by National Natural Science Foundation of China (41304046)
文摘Joint inversion of teleseismic body-wave data and strong ground motion waveforms was applied to determine the rupture process of the 2010 Mentawai earthquake. To obtain stable solutions, smoothing and non-negative constraints were introduced. A total of 33 teleseismic stations and 5 strong ground motion stations supplied data. The teleseismic and strong ground motion data were separately windowed for 150 s and 250 s and bandpass filtered with frequencies of 0.001e1.0 Hz and 0.005e0.5 Hz, respectively. The finitefault model was established with length and width of 190 km and 70 km, and the initial seismic source parameters were set by referring to centroid moment tensor(CMT) solutions. Joint inversion results indicate that the focal mechanism of this earthquake is thrust fault type, and the strike, dip, and rake angles are generally in accordance with CMT results. The seismic moment was determined as 5.814 1020Nm(Mw7.8) and source duration was about 102 s, which is greater than those of other earthquakes of similar magnitude. The rupture nucleated near the hypocenter and then propagated along the strike direction to the northwest, with a maximum slip of 3.9 m. Large uncertainties regarding the amount of slip retrieved using different inversion methods still exist; however, the conclusion that the majority of slip occurred far from the islands at very shallow depths was found to be robust. The 2010 Mentawai earthquake was categorized as a tsunami earthquake because of the long rupture duration and the generation of a tsunami much larger than was expected for an earthquake of its magnitude.
