龙首二级面板堆石坝三维真非线性地震反应分析和评价     

赵剑明  常亚屏  陈宁 《岩土力学》2004,25(Z2):388-392

基于土石料三维粘弹塑性动力本构模型,并采用新型三维各向异性有厚度薄单元来模拟面板和堆石的接触面特性,建立了高面板堆石坝地震反应分析的三维真非线性动力分析方法.利用坝料动力特性的大型三轴试验成果,分析计算了龙首二级(西流水)面板堆石坝的地震反应,主要包括加速度反应、堆石体应力反应及坝体单元抗震安全系数、面板应力反应和变形及接缝位移、高趾墙动力反应等.为大坝的抗震设计提供了有力的技术依据.  相似文献   

南极冰貌卫星影像条带噪声的剔除          下载免费PDF全文

鄂栋臣  沈强 《极地研究》2004,15(1):1-10

本文在简要叙述条带噪声形成原因的基础上 ,针对南极地区的ASTER 1A的可见光影像中出现的条带噪声的现象 ,通过设计了基于切比雪夫窗、凯瑟窗的FIR滤波器和约束最小二乘FIR滤波器对其条带噪声进行剔除 ,这两种滤波器能够尽可能地剔除条带 ,同时使影像的灰度分布发生最小畸变。并通过与其他方法 (例如 :低通滤波 ,直方图匹配等 )比较 ,说明这两种滤波的方法优于其他的方法  相似文献   

Viscoelastic–afterslip concurrence: a possible mechanism in the early post-seismic deformation of the M_w 7.6, 1999 Chi-Chi (Taiwan) earthquake     

Shyh-Yang Sheu  Chiou-Fen Shieh 《Geophysical Journal International》2004,159(3):1112-1124

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A 3D BEM-FEM methodology for simulation of high speed train induced vibrations   总被引：3，自引：1，他引：3  

J. O'Brien  D.C. Rizos   《Soil Dynamics and Earthquake Engineering》2005,25(4):289-301

This work presents an efficient methodology for the analysis of vibrations in a railroad track system, induced by the passage of conventional and high-speed trains. To this end the Boundary Element Method is used to model the soil-tie system within the framework of impulse response techniques. Conventional Finite Element Methods along with Newmark's integration is used for the modeling of the rail system. The two methods are coupled at the tie-rail interface and the solution is obtained following a staggered, time marching scheme in an efficient manner. The methodology accounts for Soil-Structure Interaction and traveling wave effects. In addition, this work identifies the parameters that affect the efficient modeling of railroad track systems as they pertain to the proposed solution methodology.  相似文献   

Computation of response spectra from mining tremors using neural networks     

K. Ku niar  E. Maci&#x;g  Z. Waszczyszyn 《Soil Dynamics and Earthquake Engineering》2005,25(4):331-339

Underground coal and copper ore exploitation in two Polish mining regions causes mining tremors and a series of other negative phenomena in the environment. Although these tremors are strictly connected with human activity, they differ considerably from other paraseismic vibrations. The moment of their occurrence is not to be foreseen likewise for earthquakes. The main problem discussed in the paper was formulated as the neural network evaluation of a relation between mining tremor energies, epicentral distances and acceleration response spectra. Back-propagation neural networks with Resilient back-propagation learning method were used. Each input vector included information about the mining tremor energy and the epicentral distance. Values of acceleration response spectrum were expected as the outputs of neural networks. Neurally evaluated spectra were compared with spectra computed on the basis of experimental data. After the network is trained and tested, it can be used for mapping of new data of mining tremor energies and epicentral distances into the spectra. Then, what is the substantial advantage of neural approach, the prediction of acceleration response spectra can be performed without recording of surface vibrations. In the light of the results, it is visible that the presented way of computation of acceleration response spectra can be peculiarly applied to prognosis of mining tremors influences on structures.  相似文献   

云南宁蒗地震应急对策与探讨     

王学仁 《地震工程学报》2005,27(4):377-379

0引言1998年8月至2000年1月在云南省丽江地区宁蒗县境内先后发生13次4~6.2级地震。这一组强震事件前,丽江行署地震局前方工作组、宁蒗县地震局根据多年的预报经验两次向中国地震局和省地震局填报了临震预报卡,准确判定了各个阶段的震情发展趋势,较成功地实现了对这组地震事件的临震预报。与此同时,向丽江地委、行署、宁蒗县委、县政府等明确提出了地震应急对策措施和建议。震前行署地震局前方工作组到极震区的烂泥箐乡开展了防震减灾科普知识宣传活动,为地方政府和震区的人民群众在震前及时实施各项有效的防震减灾措施奠定了基础,对减少灾区…  相似文献   

The dependence of response spectrum on the tectonic ambient shear stress field     

李保昆  陈培善  白彤霞 《地震学报(英文版)》2005,18(3):313-321

Introduction The acceleration response spectrum and peak ground acceleration are the necessary and im-portant parameters in earthquake-resistant design at present. They are still active research field. With the increase of digital high accurate strong motion observation data, especially the earth-quakes of Loma Prieta (M=7.0) in 1989; Landers (M=7.3) in 1992; Big Bear (M=6.4) in 1994 and Northridge (M=6.7) in 1994 in USA; Kozani (M=6.6) earthquake and afteshocks in 1995 in Greece; Dinar…  相似文献   

Pseudo‐dynamic seismic response of reinforced concrete frames infilled with non‐structural brick masonry     

F. Colangelo 《地震工程与结构动力学》2005,34(10):1219-1241

This paper presents pseudo‐dynamic test results on the in‐plane seismic behaviour of infilled frames. Thirteen single‐storey, single‐bay, half‐size‐scale, reinforced concrete‐frame specimens, most of which infilled with non‐structural masonry made of perforated bricks and cement mortar are tested. The infills are in contact with frames, without any connector; openings are not covered. The frames are different in their strength and details, reinforcement grade, and aspect ratio. Seismic input is the 1976 Tolmezzo (Friuli, Italy) ground acceleration, to which specimens are subjected two times: virgin and damaged by the previous test. The global seismic response of initially virgin infilled specimens considerably differs from that of bare specimens. This follows a dramatic change of properties: compared to a bare frame, the initial stiffness increases by one order of magnitude, and the peak strength more than doubles. The peak drift lessens; however, the displacement ductility demand does not. The energy demand is greater. Nevertheless, the influence of infill decreases as damage proceeds. Displacement time histories of damaged specimens are quite similar. At the local level, infill causes asymmetry and concentration of the frame deformation. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Seismic response analysis of multidrum classical columns     

Dimitrios Konstantinidis  Nicos Makris 《地震工程与结构动力学》2005,34(10):1243-1270

This paper presents a numerical investigation on the seismic response of multidrum classical columns. The motivation for this study originates from the need to understand: (a) the level of ground shaking that classical multidrum columns can survive, and (b) the possible advantages or disadvantages of retrofitting multidrum columns with metallic shear links that replace the wooden poles that were installed in ancient times. The numerical study presented in this paper is conducted with the commercially available software Working Model 2D?, which can capture with fidelity the sliding, rocking, and slide‐rocking response of rigid‐body assemblies. This paper validates the software Working Model by comparing selected computed responses with scarce analytical solutions and the results from in‐house numerical codes initially developed at the University of California, Berkeley, to study the seismic response of electrical transformers and heavy laboratory equipment. The study reveals that relative sliding between drums happens even when the g‐value of the ground acceleration is less than the coefficient of friction, µ, of the sliding interfaces and concludes that: (a) typical multidrum classical columns can survive the ground shaking from strong ground motions recorded near the causative faults of earthquakes with magnitudes M_w=6.0–7.4; (b) in most cases multidrum classical columns free to dislocate at the drum interfaces exhibit more controlled seismic response than the monolithic columns with same size and slenderness; (c) the shear strength of the wooden poles has a marginal effect on the sliding response of the drums; and (d) stiff metallic shear links in‐between column drums may have an undesirable role on the seismic stability of classical columns and should be avoided. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Evolutionary aseismic design and retrofit of structures with passive energy dissipation     

G. F. Dargush  R. S. Sant 《地震工程与结构动力学》2005,34(13):1601-1626

A new computational framework is developed for the design and retrofit of building structures by considering aseismic design as a complex adaptive process. For the initial phase of the development within this framework, genetic algorithms are employed for the discrete optimization of passively damped structural systems. The passive elements may include metallic plate dampers, viscous fluid dampers and viscoelastic solid dampers. The primary objective is to determine robust designs, including both the non‐linearity of the structural system and the uncertainty of the seismic environment. Within the present paper, this computational design approach is applied to a series of model problems, involving sizing and placement of passive dampers for energy dissipation. In order to facilitate our investigations and provide a baseline for further study, we introduce several simplifications for these initial examples. In particular, we employ deterministic lumped parameter structural models, memoryless fitness function definitions and hypothetical seismic environments. Despite these restrictions, some interesting results are obtained from the simulations and we are able to gain an understanding of the potential for the proposed evolutionary aseismic design methodology. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献