RONG?Mian-shui , LI?Xiao-jun , LU?Tao
2007, 29(4):297-302.
Abstract:An explicit finite element-finite difference method is performed to evaluate the part-projecting topography effects on the seismic response of visco-elastic sites. The different spectrum properties under the conditions of different high-width ratios (H/L value) and different angles of incidence are compared, the effect of multi-mesa is analysed also, The results show that for pres- ence of part-projecting topography, the H/L value and the direction of incident waves significantly affect the spectrum property, the effect of the direction of the incident wave is especially remarkable, the presence of multi-mesa also increases the amplification effect of sites.
ZHENG?Kai-feng , WEN?Shu-dong , LI?Huai-guang
2007, 29(4):303-306.
Abstract:For the phenomena of energy dissipation of inelastic beam under severe earthquake, the shock absorption project of setting inelastic beam in double thin-wall high piers of continuous frigid frame bridge is studied. Two bridge models with or not with inelastic beam are calculated separately, and the changes of moment, shear force and displacement are compared. The result is that if setting inelastic beam, the moment declines greatly, and shear force increases a little, and the displacement's maximum is unconspicuous for the pier.
LIANG?Qing-guo , HAN?Wen-feng , ZHAO?Shi-yao
2007, 29(4):307-313.
Abstract:Based on the theory of linear-elastic fracture mechanics, the influence of vertical seismic action on seismic dynamic failure of jointed rock mass is discussed. When a single peak acceleration loads on rock mass, the severest accelerated direction is horizontal slip-outward, and for acceleration with two directions, the severest ground motions are the combination of horizontal slip-outward with upward or downward according to that its failure mechanism is tenso-shear or com- presso-shear crach. The amplitude, direction and combination of horizontal and vertical accelera- tions can change the failure mechanism of rock mass and the changing is catastrophic and irreversible. The dynamic stress factor from two lower accelerations of horizontal and vertical might cause more serious failure than that from higher single acceleration. For given jointed rock mass and static stress field, the amplitude and direction combination of first ground motion accelera- tions causing failure in rock mass will determine the unique development direction, mechanism and final characteristics of rock mass failure, therefore, the seismic dynamic failure of rock mass is much more complex than static failure. The influence of vertical seismic action on seismic dynamic failure of jointed rock mass should be considered comprehensively.
WANG?Ai-guo , SHI?Yu-cheng , LIU?Yu
2007, 29(4):314-318,329.
Abstract:On the base of analysing earthquake risk, geological and geophysical conditions for Zhongwei active fault zone where Daliusu dam-site located, the potential earthquake deformation and stress near the dam in the condition of earthquake with Ms6.5, Ms7.0 and Ms7.5 on the fault F201 in the fault zone are simulated using 3D finite element method. The calculation results shows that if an earthquake of Ms≥6.5 occurres on the fault F201, the ground earthquake deformation and stress would exceed the cracking limit of crust rock at least in the range of 3 km at south of the fault, the earthquake strain of Daliushu dam-site would be over 10.4 and the stress would be several megapascal (MPa), which will lead to the anti-rupture problem hard to solve in engineering project yet.
GUO Xiao , ZHANG?Yuan-sheng , SHEN?Hai-liang , ZHANG?Hui
2007, 29(4):319-325.
Abstract:Using digital seismograms recorded by Gansu digital seismic network, the inelastic attenuation coefficient is calculated based on genetic algorithm and the method proposed by Atkinson. Then, the site response and source parameters are inversed by Moya method. The inversion results indicate that the frequency-dependent of inelastic attenuation Q value in the middle-east segment of Qilianshan is estimated as :Q(f)=687.9f^0.446. Excepting Huangyuan station, the site response at other stations show amplifications in different extent. The stress drops of all 28 earthquakes range between 0.2 to 4 MPa, dominantly distribute between 0.2 and 2 MPa. The dependence of corner frequency on seismic moment, seismic magnitude is also found.
WANG?Yan , WANG?Hai-jun , LIU?Jun-min
2007, 29(4):326-329.
Abstract:Threshold Monitoring is a method that using real seismic data to evaluate the monitoring capability of Seismological network. After pretreatment to data of seismic stations, the shortterm average (STA) instead of signal's amplitude is used for calculating events' magnitude. In this article a formula which using short-term average and epicentral distance to compute events' magni- tude is given. Seismic data from Xinjiang network are used to emendate magnitude of seismic stations. At last, an example to show how to use site-specific threshold monitoring is given and Xin- jiang network's monitoring ability in target area is analyzed.
ZHANG?Wen-ming , GAO?Da-feng , SU?Jun , WANG?Hua
2007, 29(4):330-334.
Abstract:The principle and actualizing steps of nonlinear static procedure for performance-based seismic response (Pushover method) are expatiated, and it is applied to a example of 10 story RC frame structure. The results are compared with those from earthquake response spectrum method, equivalent base shear method and time history method. Its main calculation procedures are summarized by software of ETABS. It is shown that Pushover method can meet different ductility demands of existing structures which are similar to the example in performance-based seismic evaluation.
CHEN?Jian-bo , SHEN?Jun , LI?Jun , YANG?Ji-lin , HU?Wei-hua , ZhAO?Xin , ZENG?Xian-wei
2007, 29(4):335-340.
Abstract:Kusongmuxieke mountain front fault is one of important border faults of the north fringe of rejuvenated orogenic belt in west segment of north Tianshan, it is found and determined in our research that it is an active fault. The fault can be divided into three segments. The east segment mainly consists of four en echelon faults with length of 9~13 km, and still moves inten- sively in Later Pleistocene and Holocene Epoch. Since Later Pleistocene, vertical slippage of single fault has been 3~4 m, vertical active rate is 0.23~0.33 mm/a, and vertical slippage of single fault is 0.5~0.8 m since Holocene Epoch. New movement of the middle segment dislocates different geomorphologic units which formed from Middle Pleistocene to Holocene Epoch, forms multilevel fault escarpments and a 8~10 km long earthquake deformation belt. Since Later Pleistocene the vertical active rate is 0.5 mm/a. The west segment has no movement since Later Pleistocene.
LIU?Xing-wang , YUAN?Dao-yang , GE?Wei-peng
2007, 29(4):341-346,351.
Abstract:Based on analyzing the development and distribution of Yellow River terraces in Lanzhou city, using the high-resolution differential GPS measuring and DEM (1:10 000) mapping data, the terrace map and profiles along and cross the river are gotten. Complaining with the dating results of the different grade terraces, the tectonic deformation characters of the terraces are studied, and the quantitative parameters of terrace deformation characters, the widths of deformation zones, the extents and velocities of deformation in active fault zone are obtained. In conclusion, it is indicated that folding effect plays major role in tectonic deformation of Lanzhou Basin in late-Quaternary, while tectonic activity of faults has been not clear since that time.
HAO?Xiao-qiang , YANG?Shi-sheng , QIN?Rong
2007, 29(4):347-351.
Abstract:Based on the code for seismic design of buildings, the code for reinforced concrete structure design and the research result about the existed buildings, by consulting the idea of strength and toughness evaluation theory of reinforced concrete, a new evaluation system for anti-seismic capability of reinforced concrete structure including the shear wall, which is suitable for Chinese engineering practice is presented in this paper. An existed building example is evaluated by the program EAC--RCSW, which is created according to the theory proposed by this paper. It is proved that this evaluation method could quantitatively evaluate the anti-seismic capability of the existing reinforced concrete structure including the shear wall.
XU?Ping , TANG?Xian-fu , XIA?Tang-dai
2007, 29(4):352-356.
Abstract:Adapting the equivalent viscoelastic model considering the characteristics of the soils at the site and some mechanics parameters such as maximum shear modulus, dynamic elastic modulus and damping ratio, determined by tests, the earthquake responses of Qinhe inverted siphon pipes are :studied based on the method of integral in time domain and interation, and distribution regularity of the absolute displacement at the bottom center of the pipes, relative displacement of the top center to the bottom center of the pipes, and dynamic and static synthesis principal stresses are analyzed. According to the analysis results of finite elements method and the design equation of concrete limit bearing capacity, the security degree of resistance capacity of tensile and compress for the concrete pipes are checked. The results indicate that Qinhe inverted siphon pipes satisfy with earthquake-resistance requirements effected when man-made, the adjusted E1 Centro and Pulgas seismic waves inputted individually.
MA?He-qing , LUO?Guo-fu , WANG?Yin
2007, 29(4):357-363.
Abstract:Since 1955, the siesmicity with M≥5.0 in the juncture region of Tibet, Qinghai, S chuan and Yunnan provinces has been in a alternate rhythm state of quietude and activity. In th S paper, the 10 whole quiet-active periods are discussed. Some phenomena represented by the 10 periods, and their correlative relations with the seismicity in a large area of Tibet-Qinghai Block are discussed also.
XU?Xin-xue , CHEN?Yu-kun , LIU?Jun-chang , ZHANG?Bao-hua , XIA?Xun-yin
2007, 29(4):364-370.
Abstract:Based on the data of Magnetotelluric sounding profile from Langfang of Hebei province to Dagang of Tianjin City with 110 km, through the methods of far reference with Robust treatment and inversion, the analysis of apparent resistivity, two-dimensional skewness and electrical axes is done. The results show the touch relationships among three tectonic units of Jizhong depression Cangxian uplifted zone and Huanghua depression, divide the electrical conductivity structure layers in the crust and upper mantle. Cangdong fault and Dacheng fault are important structures in the area which contral the depressions in both side of uplifted zone and sedimentation. The deep of faults correspond updifted zone of high conductive layer of upper mantle.
ZHANG?Jian-guo , QIAO?Zi-yun , ZHANG?Xin-dong , SUN?Qing
2007, 29(4):371-376.
Abstract:By using the method of correlation analysis to geomagnetic data Z21 recorded in 8 geomagnetic stations in Hebei Province from 1981 to 2006. It is found that abnormal correlation coefficient have good relationship with the earthquakes of magnitude Ms≥5.0 in Hebei and neighboring area. In 26 years 18 abnormal events appeared, in which 13 events respond to Ms≥5.0 earthquake in 10 months. In this way, 15 earthquakes should be predicted, 3 were falsed for prediction and 2 were missed. A initial and quota parameter suitable for the earthquake prediction in Hebei Province is suggested.
TANG?Li-hua , LI?Meng , WANG?Hai-tao
2007, 29(4):377-379,384.
Abstract:Using the experiential method, the horizontal and vertical acceleration attenuation relationships of moderate-strong earthquake in soil site are obtained by directly regressing the acceleration recordings of earthquakes(Ms≥4) from 1996 to 2003 in Jiashi--Bachu region. The horizontal pattern of the attenuation relationship is applicable to the earthquakes with magnitude 4.0~ 6.9, while the vertical pattern is applicable to earthquakes with magnitude 4.0~5.9.
QIN?Jian-zeng , LI?Qing-lin , GUO?De-ke , FENG?Jian-lin , ZHANG?Rui-min , XIE?Ru-yi , ZHANG?Xiao-pu
2007, 29(4):380-384.
Abstract:The variation feature of gravity field and seismicity before and after Fanxian ML4. 3 earthquake discussed. Since May in 2003, the gravity field showed a tendentious descent-ascentaccelerative ascent style, and the earthquake occurred in accelerative change stage. After the tendency anomalies of point-value at some measuring stations and of segment-value of measuring segment lasted a considerable time, the variation amplitudes were(30~60) × 10^-8m · s^-2. After the earthquake the gravity anomaly in this region did not recovered. Variations of gravity field in this area may be caused by the earth crust deformation, quality transition in deep crust and fault creep deformation. Meanwhile the earthquake prediction according to the gravity anomalies is in- troduced.
CHEN?Jian-jun , XU?Yu-hong , LI?Xing-jian , CHEN?Jun , LI?Dong-sheng
2007, 29(4):385-387.
Abstract:The general principles of digital filters, and the application of Butterworth low-pass filter, high-pass filter and band-pass filter on routine work at Gaotai seismic station are introduced in this paper.
Sopyright:China Earthquake Engineering Journal