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A simplified analysis procedure for the non-linear hysteretic earthquake-response of earth dams is presented. The dam is modelled as a one-dimensional hysteretic shear-wedge subjected to base excitation. The hysteretic stress-strain behaviour of the dam materials is modelled by using elasto-plastic constitutive equations based on multi-surface kinematic plasticity theory. The method is based on a Galerkin formulation of the equations of motion in which the solution is expanded using eigenmodes of the linearized problem defined over the spatial domain occupied by the dam. The technique is applied to analyse the non-linear dynamic response of an earth dam subject to two very different input ground motions. The following investigations are presented: (i) comparison between the results obtained using two soil models depicting different nonlinear properties, (ii) comparison between the results of the one-mode and the multi-mode solution expansions, (iii) comparison with the results obtained through an elaborate finite element representation of the dam, and finally, (iv) comparison with the results obtained through the Makdisi-Seed11 iterative procedure for earth dam analysis. The comparisons show that the proposed technique can be used to determine adequately the transient earthquake response of long earth dams. Furthermore, the efficiency and low computational cost make the technique very attractive; it can easily and systematically be extended to two- and three-dimensional calculations of earth dam response. 相似文献
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《地震工程与结构动力学》2018,47(5):1309-1328
A direct finite element method for nonlinear earthquake analysis of 2‐dimensional dam–water–foundation rock systems has recently been presented. The analysis procedure uses standard viscous‐damper absorbing boundaries to model the semi‐unbounded foundation‐rock and fluid domains and specifies the seismic input as effective earthquake forces at these boundaries. Presented in this paper is a generalization of the direct finite element method with viscous‐damper boundaries to 3‐dimensional dam–water–foundation rock systems. Step‐by‐step procedures for determining the effective earthquake forces starting from a ground motion specified at a control point on the foundation‐rock surface is developed, and several numerical examples are computed and compared with independent benchmark solutions to demonstrate the effectiveness of the analysis procedure for modeling 3‐dimensional systems. 相似文献
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El Infiernillo, a 145 m high rockfill dam in Mexico built in a narrow V-shaped canyon, was subjected to eight major earthquakes since its construction. In this study, the dynamic dam response is analysed using (i) the recorded November 15, 1975 bedrock-crest acceleration histories and (ii) the results of a 1970 full-scale test conducted by UNAM, in which eight upstream–downstream and longitudinal resonant frequencies and configurations were observed and documented. These observed and seismically induced dynamic responses are compared herein to predictions of two different numerical models of El Infiernillo dam; a newly developed simplified three-dimensional (3D) model, and a 3D finite element model. The dynamic dam response characteristics are assessed, and performance of the employed numerical models is evaluated. It is found that (i) higher modes of vibration had participated significantly in the recorded seismic response and (ii) upstream–downstream response is well represented by the two numerical models employed. Using the simplified model, the September 19, 1985 earthquake non-linear response is computed and shown to compare satisfactorily with its recorded counterpart in the upstream-downstream and vertical directions. The largest computed dynamic accelerations, stresses and strains are found to occur within the upper third of the dam body. 相似文献
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Direct finite element method for nonlinear analysis of semi‐unbounded dam–water–foundation rock systems 
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下载免费PDF全文 A direct finite element method is presented for nonlinear earthquake analysis of interacting dam–water–foundation rock systems. The analysis procedure applies viscous damper absorbing boundaries to truncate the semi‐unbounded fluid and foundation‐rock domains and specifies at these boundaries effective earthquake forces determined from the design ground motion defined at a control point on the free surface. The analysis procedure is validated numerically by computing the frequency response functions and transient response of an idealized dam–water–foundation rock system and comparing with results from the substructure method. Because the analysis procedure is applicable to nonlinear systems, it allows for modeling of concrete cracking, as well as sliding and separation at construction joints, lift joints, and at concrete–rock interfaces. Implementation of the procedure is facilitated by commercial finite element software with nonlinear material models that permit modeling of viscous damper boundaries and specification of effective earthquake forces at these boundaries. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Different procedures are compared for the three-dimensional seismic cracking analysis of gravity and arch dams during strong earthquakes. The fracture procedures include the extended finite element method with cohesive constitutive relations, crack band finite element method with plastic-damage relations, and the finite element Drucker−Prager elasto-plastic model. These procedures are used to analyze the nonlinear dynamic response of Koyna dam to the 1967 Koyna earthquake and the seismic cracking of the Dagangshan arch dam subjected to design earthquake. The cracking process and profiles of the two dams using the three different procedures are compared. The applicability and the suitability of the three procedures for seismic cracking analysis of gravity and arch dams are discussed. 相似文献
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A magnitude 4.3 earthquake occurred near Pacoima Dam on 13 January 2001. An accelerometer array that had been upgraded after the Northridge earthquake recorded the motion with 17 channels on the dam and the dam–foundation interface. Using this data, properties of the first two modes are found from a system identification study. Modal properties are also determined from a forced vibration experiment performed in 2002 and indicate a significantly stiffer system than is estimated from the 2001 earthquake records. The 2001 earthquake, although small, must have induced temporary nonlinearity. This has implications for structural health monitoring. The source of the nonlinear behaviour is believed to be loss of stiffness in the foundation rock. A finite element model of Pacoima Dam is constructed and calibrated to match modal properties determined from the system identification study. A dynamic simulation of the 2001 earthquake response produces computed motions that agree fairly well with the recorded ones. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Numerical investigation of the response of the Yele rockfill dam during the 2008 Wenchuan earthquake
In this paper the seismic response of a well-documented Chinese rockfill dam, Yele dam, is simulated and investigated employing the dynamic hydro-mechanically (HM) coupled finite element (FE) method. The objective of the study is to firstly validate the numerical model for static and dynamic analyses of rockfill dams against the unique monitoring data on the Yele dam recorded before and during the Wenchuan earthquake. The initial stress state of the dynamic analysis is reproduced by simulating the geological history of the dam foundation, the dam construction and the reservoir impounding. Subsequently, the predicted seismic response of the Yele dam is analysed, in terms of the deformed shape, crest settlements and acceleration distribution pattern, in order to understand its seismic behaviour, assess its seismic safety and provide indication for the application of any potential reinforcement measures. The results show that the predicted seismic deformation of the Yele dam is in agreement with field observations that suggested that the dam operated safely during the Wenchuan earthquake. Finally, parametric studies are conducted to explore the impact of two factors on the seismic response of rockfill dams, i.e. the permeability of materials comprising the dam body and the vertical ground motion. 相似文献
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A nonlinear finite element model for earthquake response analysis of arch dam–water–foundation rock systems is proposed in this paper. The model includes dynamic dam–water and dam–foundation rock interactions, the opening of contraction joints, the radiation damping of semi‐unbounded foundation rock, the compressibility of impounded water, and the upstream energy propagating along the semi‐unbounded reservoir. Meanwhile, a new equivalent force scheme is suggested to achieve free‐field input in the model. The effects of the earthquake input mechanism, joint opening, water compressibility, and radiation damping on the earthquake response of the Ertan arch dam (240 m high) in China are investigated using the proposed model. The results show that these factors significantly affect the earthquake response of the Ertan arch dam. Such factors should therefore be considered in the earthquake response analysis and earthquake safety evaluation of high arch dams. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The paper presents a general procedure for dealing with coupled fluid-structure interaction under dynamic load. This incorporates a facility for dealing with a cavitating fluid and is based on the Newton displacement potential. Several solutions are obtained for two-dimensional gravity dam problems illustrating the effects of cavitation on earthquake response and blast loading. 相似文献
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In this study, the earthquake damage response of the concrete gravity dams is investigated with considering the effects of dam–reservoir interaction. A continuum damage model which is a second-order tensor and includes the strain softening behavior is selected for the concrete material. The mesh-dependent hardening technique is adopted such that the fracture energy dissipated is not affected by the finite element mesh size. The dynamic equilibrium equations of motion are solved by using the improved form of the HHT-α time integration algorithm. Two dimensional seismic analysis of Koyna gravity dam is performed by using the 1967 Koyna earthquake records. The effects of damage on the earthquake response of concrete gravity dams are discussed. Comparison of the Westergaard and Lagrangian dam–reservoir interaction solutions is made. The effects of viscous damping ratio on the damage response of the dam are also studied. 相似文献
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A dynamic analysis of elastic–viscoplastic systems, incorporating the modal co-ordinate transformation technique, is presented. The formulation results in uncoupled incremental equations of motion with respect to the modal co-ordinates. The elastic–viscoplastic model adopted allows the analysis not to involve yielding regions and loading/unloading processes. An implicit Runge–Kutta scheme together with the Newton–Raphson method are used to solve the non-linear constitutive equations. Stability and accuracy of the numerical solution are improved by utilizing a local time step sub-incrementing procedure. Applications of the analyses to multi-storey shear buildings show that good results can be obtained for the maximum displacement response by including only a few lower modes in the computation, but the prediction of the ductility factor response tends to underestimate the peak values when too few modes are used. In addition, stable and valid results can be obtained even with a sizable time step increment. 相似文献
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Tensile stresses exceeding the tensile strength of concrete can develop in concrete dams subjected to earthquake ground motion. This study examines the earthquake response of gravity dams including tensile cracking of the concrete. The interaction between the dam and compressible water is included in the analysis using a numerical procedure for computing the non-linear dynamic response of fluid-structure systems. The crack band theory is used to model tensile cracking with modifications to allow for the large finite elements necessary for dam analysis. The earthquake response of a typical gravity dam monolith shows that concrete cracking is an important non-linear phenomenon. Cracking is concentrated near the base of the dam and near the discontinuities in the face slope. The extensive cracking, which develops due to ground motion typical of maximum credible earthquakes, may affect the stability of dams during and after strong earthquakes. 相似文献
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In this paper, seismic analysis of plane RC frame structures with High Damping Rubber Bearings (HDRBs) base-isolation systems is performed in the non linear range. For RC members, a modified version of hysteretic Park model is used. For HDRB isolators, a new hysteretic model is presented, which is able to accurately predict the mechanical response in the large strain range. The dynamic equilibrium equations are solved making use, at each time step, of a block iterative Newton–Raphson scheme: the frame is divided into superelements (beams and columns) with master nodes at the extremities and internal local nodes for the computation of relations between end moments and relative rotations at superelement extremities. The effectiveness of HDRB base-isolation systems to reduce inelastic deformations in the RC superstructures is investigated through some numerical examples. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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Earthquake safety assessment of concrete arch and gravity dams 总被引：9，自引：1，他引：8
Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessment of concrete dams are reviewed and discussed. First, the rate-dependent behavior of concrete subjected to earthquake loading is examined, emphasizing the properties of concrete under cyclic and biaxial loading conditions. Second, a modified four-parameter Hsieh-Ting-Chen viscoplastic consistency model is developed to simulate the rate-dependent behavior of concrete. The earthquake response of a 278m high arch dam is analyzed, and the results show that the strain-rate effects become noticeable in the inelastic range. Third, a more accurate non-smooth Newton algorithm for the solution of three-dimensional frictional contact problems is developed to study the joint opening effects of arch dams during strong earthquakes. Such effects on two nearly 300m high arch dams have been studied. It was found that the canyon shape has great influence on the magnitude and distribution of the joint opening along the dam axis. Fourth, the scaled boundary finite element method presented by Song and Wolf is employed to study the dam-reservoir-foundation interaction effects of concrete dams. Particular emphases were placed on the variation of foundation stiffness and the anisotropic behavior of the foundation material on the dynamic response of concrete dams. Finally, nonlinear modeling of concrete to study the damage evolution of concrete dams during strong earthquakes is discussed. An elastic-damage mechanics approach for damage prediction of concrete gravity dams is described as an example. These findings are helpful in understanding the dynamic behavior of concrete dams and promoting the improvement of seismic safety assessment methods. 相似文献
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Owing to the devastating M7.6 earthquake of 20 June 1990 that occurred in the northern province of Iran, Sefid‐rud concrete buttress dam located near the epicenter was severely shaken. The crack penetrated throughout the dam thickness near slope discontinuity, causing severe leakage, but with no general failure. In this study, nonlinear seismic response of the highest monolith with empty reservoir is investigated experimentally through model testing. A geometric‐scaled model of 1:30 was tested on a shaking table with high‐frequency capability to study dynamic cracking of the model and serve as data for nonlinear computer model calibration. Three construction joints are set up in the model to simulate effects of construction aspects. The experimental results are then compared with smeared crack and damage mechanics finite‐element simulations using nonlinear concrete constitutive models based on fracture mechanics. The crack patterns obtained from numerical models are in good agreement with those obtained from shaking table tests for the case of including construction joint effects and rigid foundation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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As the forward directivity and fling effect characteristics of the near-fault ground motions, seismic response of structures in the near field of a rupturing fault can be significantly different from those observed in the far field. The unique characteristics of the near-fault ground motions can cause considerable damage during an earthquake. This paper presents results of a study aimed at evaluating the near-fault and far-fault ground motion effects on nonlinear dynamic response and seismic damage of concrete gravity dams including dam-reservoir-foundation interaction. For this purpose, 10 as-recorded earthquake records which display ground motions with an apparent velocity pulse are selected to represent the near-fault ground motion characteristics. The earthquake ground motions recorded at the same site from other events that the epicenter far away from the site are employed as the far-fault ground motions. The Koyna gravity dam, which is selected as a numerical application, is subjected to a set of as-recorded near-fault and far-fault strong ground motion records. The Concrete Damaged Plasticity (CDP) model including the strain hardening or softening behavior is employed in nonlinear analysis. Nonlinear dynamic response and seismic damage analyses of the selected concrete dam subjected to both near-fault and far-fault ground motions are performed. Both local and global damage indices are established as the response parameters. The results obtained from the analyses of the dam subjected to each fault effect are compared with each other. It is seen from the analysis results that the near-fault ground motions, which have significant influence on the dynamic response of dam–reservoir–foundation systems, have the potential to cause more severe damage to the dam body than far-fault ground motions. 相似文献
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In this paper,an explicit finite element method to analyze the dynamic responses of three-medium coupled systems with any terrain is developed on the basis of the numerical simulation of the continuous conditions on the bounda-ries among fluid saturated porous medium,elastic single-phase medium and ideal fluid medium.This method is a very effective one with the characteristic of high calculating speed and small memory needed because the formulae for this explicit finite element method have the characteristic of decoupling,and which does not need to solve sys-tem of linear equations.The method is applied to analyze the dynamic response of a reservoir with considering the dynamic interactions among water,dam,sediment and basement rock.The vertical displacement at the top point of the dam is calculated and some conclusions are given. 相似文献
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A nonlinear, slip-joint element for analyzing the effect of discontinuities on a concrete, arch dam's seismic response is developed. The joint element has been incorporated into a finite-element-based, solution for predicting dynamic structural response. This joint model, plus the numerical procedure incorporated into the incremental solution, models inter-element impact across a joint when adjacent, structural elements separate and later collide. Collision is incorporated into the incremental analysis by calculating the exchange of momentum and energy with the equations describing eccentric, rigid-body impact. Joint material's force-deflection relations are multi-linear with hysteresis. Coulomb friction is also modeled. The joint element and numerical procedure have been tested with two models. The first is a segmented arch of seven, straight beam elements connected to one another. The arch dam has been experimentally tested. Analytical results are compared with experimental results from the sealed model. Second is a rectangular plate model subject to lateral base accelerations. One horizontal edge is fixed and the opposite edge is free. The vertical edges may be fixed or connected to the base by joint elements. 相似文献