Institute of Earthquake Engineering of Jiangsu Province

Nanjing, China

Institute of Earthquake Engineering of Jiangsu Province

Nanjing, China
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Zhang X.-L.,Nanjing University of Technology | Li X.-J.,Nanjing University of Technology | Li X.-J.,China Earthquake Administration | Zhou Z.-H.,Nanjing University of Technology | And 2 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2017

It has long been known that surface topography can have significant effect on seismic motions, and the numerical simulations are important tools for study on the complex topographic effect. Most applications of viscous-elastic artificial boundary assumed that the boundary is regular, however this is not the case, and the computational error will inevitably increase. In this paper, a simplified seismic input method was proposed, which is based on the explicit finite element method with viscous-elastic artificial boundary conditions and the two dimensional solution for three-dimensional problems. The numerical results from the homogeneous half-space model indicated that the wave input method is reasonable. We also establish a three-dimensional (3D) canyon model and four two-dimensional (2D) canyon models according to the real ground elevation data of steep topography in Taoping, Sichuan province, China. The seismic response of the five models in the case of SV wave vertical incidence is studied. Among them, the seismic input of the four 2D canyon models uses the conventional method, while the method introduced in this paper is applied in the 3D canyon model. The results show that it is necessary to establish a 3D model instead of 2D model according to the real ground elevation data. The calculating method of lateral boundary's free field for 3D complex topography is presented in this paper to provide a reference for the seismic effect of 3D complex terrain, and it can also be used to deal with the seismic oblique incidence in 3D complex terrain. © 2017, Science Press. All right reserved.

Hong H.,Institute of Earthquake Engineering of Jiangsu Province | Shi Y.,Lanzhou Institute of Seismology | Liu T.,Peking University | Wang H.,Institute of Earthquake Engineering of Jiangsu Province | Zhan X.,Institute of Earthquake Engineering of Jiangsu Province
Journal of Earthquake Engineering and Engineering Vibration | Year: 2014

Based on the data of field investigation, researches on characteristics and causes of ancient buliding damage in meizoseismal region and severely damaged region induced by Lushan earthquake are carried out. The structure form mainly includes wood structure, stone structure, brick wood structure and brick stone structure. Through the methods of classification and induction, it is found that the typical damage characteristics mainly include shear cut of base, walls fracture,plastering drop,and local collapse of the top. The formation mechanism of the destroyed ancient buildings are the vertical seismic action, whipping effect, change of force transferring mechanism. The damage differences induced by Lushan earthquake of different structures of ancient buildings are analyzed. The anti-seismic capacity of ancient buildings is better than ordinary buildings under the same structure. Meanwhile, the reinforcement and maintenance methods of seismic fortification, anti-seismic force transferring mechanism, and the techniques of seismic isolation and shock absorption concerning different ancient buildings are discussed. Therefore, the obtained results can offer reference to earthquake fortification of ancient buildings, and the reduction of damage loss.

Gao Z.-B.,Hohai University | Gao Z.-B.,Institute of Earthquake Engineering of Jiangsu Province | Gao Y.-F.,Hohai University | Tan H.-M.,Institute of Earthquake Engineering of Jiangsu Province
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

Considering the importance of the maximum dynamic shear modulus of saturated clay soils in calculation, lab and in-situ tests are performed. According to the 463 tests finished in the past several years, the values of the dynamic shear modulus of the same soil are different in the lab and in-situ tests. The results obtained from the lab tests are mostly less than those from the in-situ tests, and the differences become greater with the increase of depth. Based on the relationships of the maximum dynamic shear modulus in lab tests with the depth, which follows the exponential function, the statistical formula of the maximum dynamic shear modulus in lab tests and the shear wave velocity in in-situ tests are obtained. Finally, the maximum shear modulus G max derived from the above formula is applied in the case of ground seismic response computation, in which G max obtained from the in-situ tests is also used. The results show that the statistical formula is reasonable and practicable, and the differences of the maximum shear moduli obtained in different ways will have great effects on the peak ground acceleration and the characteristic period of the seismic response spectra.

Tan H.,Hohai University | Gao Z.,Institute of Earthquake Engineering of Jiangsu Province
Disaster Advances | Year: 2012

Based on the results of the resonant column test in lab and shear wave velocity test in situ of 463 saturated clayey soil samples and 233 saturated sandy soil samples in Jiangsu areas, the comparison of maximum dynamic shear modulus Gmax values from the different tests has been discussed. The comparison result shows that the differences of Gmax value respectively obtained from lab test and situ test are very great and the G max values got from situ test are almost larger than those of lab test, especially with the increase of soil depth. Furthermore, the analysis on test results also shows the Gmax value of lab test is exponential to the depth in statistic and the statistical formula of Gmax value in lab test and shear wave velocity Vs in situ test has also been proposed.

Tan H.,Hohai University | Huang Y.,Institute of Earthquake Engineering of Jiangsu Province | Chen J.,Hohai University
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013

The disastrous geology survey in water areas for underwater pipeline construction has been finished with the acoustic strata profile technique. The strata profile has been obtained, which shows the bedrock is consecutive and no fault exists in the exploration area. The existence of at least two pipelines has been proved, and the depth of the previous pipelines is in the middle of sand layers. Therefore, the suggestion of pipeline construction at the depth of about 40m below the water level has been proposed to avoid the cobble layer and provide a covering layer to prevent pipelines from erosion by currents. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).

Ding X.-M.,Hohai University | Tan H.-M.,Institute of Earthquake Engineering of Jiangsu Province
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2011

In order to obtain the dynamic response of defective large-diameter pipe pile in low strain integrity testing when subjected to transient concentrated load, a computational model and wave equation of large-diameter pipe pile with variable wave impedance were established based on radial invariability assumption. The analytical solution of wave equation in frequency domain was obtained by Laplace transformation method. The dynamic responses in time domain were obtained by Fourier inverse transformation. The results of analytical solution were compared with that of 3D finite element method and 1D wave theory. The results indicated that the results of analytical solution well matched the 3D-FEM results. The velocity responses at 90°point calculated by 3D-FEM, analytical solution and 1D wave theory had little difference. The dynamic responses at different points on top of the pile showed that the arrival time of incident wave crests varied with radius angle. The smaller the radius angle, the earlier the arrival time. The arrival time of defect reflected wave crests was different among different points when depth of defect was not very deep. However, the difference was decreased when the defect was deeper. The high-frequency interference was the least at 90°point. The results of the analytical solution could well meet the measured results.

Peng X.,Institute Of Earthquake Engineering Of Jiangsu Province | Peng X.,China Earthquake Administration | Li X.,China Earthquake Administration | Liu Q.,China Earthquake Administration
World Information on Earthquake Engineering | Year: 2011

According to the review of coseismic displacements estimated from strong-motion accelerograms since 1940,the related theory and methods are systematically summarized. The importance of the coseismic displacement and common drifting phenomenon are discussed at first. Then the effort for estimating the displacement based on accelerograms from analog phase to digital phase is presented mainly in chronological sequence. Next the noise causing drifting is divided into five models,and two kinds of corresponding estimation methodsfitting by three kinds of time histories and by two kinds of wavelet analyses are discussed. Finally, the prospects of future researches are expounded.

Peng X.,Institute of Earthquake Engineering of Jiangsu Province | Peng X.,China Earthquake Administration | Yang W.,Institute of Earthquake Engineering of Jiangsu Province
Applied Mechanics and Materials | Year: 2012

To eliminate the drifting in recordings from Ms8.0 Wenchuan earthquake, a modified two segments baseline correction method is brought up and systematic acceptance standard is presented. The method is applied to recordings from Qingping station and Bajiao station, which are closest stations to surface rupture traces. The effect of baseline correction on acceleration time history, Fourier amplitude spectrum and 5% damped relative displacement response spectrum is analyzed. © (2012) Trans Tech Publications.

Peng X.,Institute of Earthquake Engineering of Jiangsu Province | Peng X.,China Earthquake Administration | Liu L.,Tongji University | Li X.,China Earthquake Administration | Sun P.,China Earthquake Administration
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2011

Based on the field damage investigation at 170 spots for five building types, including brick-concrete, brick-timber, through type timber frame, frame structure and old buildings, in Wenchuan earthquake, the damage indices were compared between brick-concrete buildings and other four types at same spot and the corresponding correlation coefficients were obtained. Results show significant variation among different buildings for damage index in 0.2-0.6, but little variation in other range, and damage indices are highly correlated on the whole. The three directions' PGA attenuation relationships were obtained using records in 500 km region from the fault in order to analyze the correlation of damage indices and ground motion parameters. The comparison of the attenuation relations between normalized PGA and damage index indicates damage indices of brick-concrete and brick-timber buildings fit PGA well but damage indices of the old buildings damage deviate obviously. To improve the comparability, 57 pairs of strong motion records and adjacent spots within 0.1° along longitude and latitude were chosen to analyze linear correlation coefficients between PGA, PGV, PSA, PSV, PSD and damage indices. The results of this study are useful in seismic design and mutual estimation between strong motion parameters and building damage indices.

Liu B.,Institute of Disaster Prevention | Wang W.,Institute of Disaster Prevention | Peng X.,Institute of Earthquake Engineering of Jiangsu Province | Zhou Z.,Nanjing University of Technology | And 2 more authors.
International Journal of Earth Sciences and Engineering | Year: 2015

During Wenchuan Earthquake in 2008, the PGA (Peak Ground Acceleration) and spectral characteristics of main shock detected by the observation stations in Baoji, Fengxiang, Chencang and Qishan in the west of Weihe Basin differed greatly. The PGA of observation stations at Fengxiang and Qishan located in the loess tableland in the north of Weihe Fault were obviously smaller than those in Chencang station and Baoji station in the river valley plain in the south of Weihe Fault. The high-frequency components of Chencang station were much more abundant than those at Fengxian station and Qingshan station. However, these four stations are only a dozen kilometers away from each other. As shown by seismogeological data and the information of the observation stations, these stations are not significantly different in local site conditions. Considering the fact that these stations are three to four hundred kilometers away from Longmenshan Fault, the causative fault of Wenchuan Earthquake, such large differences in PGA cannot be explained by the ground motion attenuation law in this area. In this study, by using the seismogeological features and local topography, the 2-D model of those sites derived by the explicit finite element combining with local multi-transmitting artificial boundary method is used to analyze the mechanism of difference of the ground motion. Numerical simulation indicates that the presence of rock base mountain, fault scarp, fault fracture zone and overburden, which are heterogeneous media, leads to violent waveform transformation in this area. Under the double influence of scarp and fault fracture zone, the transformed wave component is the largest near the fault scarp. Under the double influence of thick and deep overburden in the center of the river valley and the basin effect, the response is the largest at Chencang station near the center of the river valley. Ground motion is significantly amplified in the scarp and loess tableland within the low-frequency range of 1-2Hz and the highfrequency range above 5Hz. For the medium-frequency range of 3-5Hz, ground motion is greatly amplified in the river valley plain. Moreover, the magnitude of amplification is basically consistent for certain frequency range. Thus, macroscopic analysis and numerical analysis indicate that the difference of the ground motion is mainly affected by dislocation basin, fault scarp and fault fracture zone under control of the non-causative fault(Weihe Fault) in Wenchuan Earthquake. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.

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