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1.
This paper is concerned with application of the h-adaptive finite element method to dynamic analysis of a pile in liquefiable soil considering large deformation. In finite element analysis of pile behavior in liquefiable soil during an earthquake, especially considering large deformation of liquefied ground, error due to discretization in the zone near the pile becomes very large. Our purpose was to refine the approximation of the finite element method. The updated Lagrangian formulation and a cyclic elasto-plastic model based on the kinematic hardening rule were adopted to deal with the nonlinearity of the soil. The mixed finite element and finite difference methods together with the u-p formulation and Biot's two-phase mixture theory were used. To improve the accuracy and increase the efficiency of finite element analysis, an h-adaptive scheme that included a posteriori error estimation and h-version mesh refinement was applied to the analysis. The calculated results of effective stress were smoothed locally by the extrapolation method and smoothed stress was used to calculate the L2 norm of the effective stress error in the last step of the calculation of each time increment. The mesh was refined by a fission procedure based on the indication of the error estimate As a numerical example, a soil–pile interaction system loaded cyclically was analyzed by our method. 相似文献
2.
A continuum theory for an improved characterization of dynamic soil–structure interaction in the framework of three‐dimensional elastodynamics is presented. Effective in demonstrating the importance of integrating free‐field and near‐field effects under general soil and foundation conditions, a compact two‐zone delineation of the soil medium is proposed as a quintessential mechanics perspective for this class of problems. Sufficient to deliver a practical resolution of some perennial analytical and experimental conflicts, a fundamental formulation commensurate to a gradated unification of the homogenization approach and any sole free‐field inhomogeneous representation is developed and implemented computationally. Specialized to the problem of a rigid circular footing on sand, a nominal set of dynamic contact stress distributions and related impedance functions by the dual‐zone theory is included for theoretical and engineering evaluation. Through its comparison with benchmark analytical solutions and relevant physical measurements, the usage of the underlying conceptual platform as an advanced yet practical foundation for general dynamic soil–structure interaction is illustrated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
3.
智能材料-结构系统在土木工程中的应用 总被引：27，自引：4，他引：23
本文在简要说明了“智材料－结构系统”的基本概念和它在土 木工程中的两种应用途径的基础上,较为系统地介绍了光纤材料,碳纤维混凝土,俞合管道、等七种智能材料在土木工程结构中的应用。 相似文献
4.
近地空中爆炸作用下钢框架结构冲击响应 总被引：2，自引：0，他引：2
采用多物质欧拉与拉格朗日耦合算法,对框架结构和混凝土地面采用Lagrange单元、空气和炸药采用多物质ALE单元,建立流固耦合有限元模型,对一个五层的钢框架结构在近地爆炸作用下冲击压力波的传播过程、结构冲击响应和变形以及破坏过程进行了数值模拟.数值模拟分析结果表明,拉格朗日-欧拉耦合算法较好地模拟了爆炸冲击波在介质中的传播和作用在结构上的爆炸荷载效应.在爆炸近区,空气爆炸冲击波的衰减速率快;爆炸产生强烈的冲击波首先使钢框架结构正面的柱和梁柱节点区产生很大的塑性变形,钢框架柱在发生爆炸的瞬间失去承载能力,最终导致建筑物整体倒塌.考虑结构变形和流体荷载间的相互影响可以较真实地模拟结构在爆炸荷载作用下的连续倒塌过程,为研究结构在爆炸荷载作用下的连续倒塌提供了有效手段. 相似文献
5.
总结了土工动力离心模型试验在边坡的地震响应、动力破坏机理、液化大变形和土与结构物动力相互作用等研究中的应用现状，提出了目前边坡动力模型试验中存在的问题，以及今后的发展方向。 相似文献
6.
Ahmad ShakibaeiniaYee-Chung Jin 《Advances in water resources》2011,34(6):794-807
Mesh-free particle (Lagrangian) methods such as Moving Particle Semi-Implicit (MPS) and Smoothed Particle Hydrodynamics (SPH) are the latest generation of methods in the field of computational fluid dynamics that attracts lots of attention in modeling applications where large interfacial deformations and fragmentations exist. Due to their mesh-free nature, these methods are capable of simulating any kind of boundary/interface deformation and fragmentations. This study aims to develop a new mesh-free particle model based on the weakly compressible MPS (WC-MPS) formulation for modeling of a dam break over a mobile bed, which is a highly erosive and transient flow problem. A multiphase model, capable of handling the density and viscosity discontinuity and in which the solid (sediment) phase is treated as a non-Newtonian fluid, is introduced. The resulting model is first validated using a two-phase dam break problem and is then applied to the mobile-bed dam break problem with different conditions, comparing the results to those obtained from some experimental works. 相似文献
7.
《Soil Dynamics and Earthquake Engineering》2003,23(4):249-253
A parallel soil–structure interaction (SSI) model is presented for applications on distributed computer systems. Substructring method is applied to the SSI system and a coupled finite–infinite element based parallel computer program is developed. In the SSI system, infinite elements are used to represent the soil which extends to infinity. In this case, a large finite element mesh is required to define the near field for reliable predictions. The resulting large-scale problems are solved on distributed computer systems in this study. The domain is represented by separated substructures and an interface. The number of substructures are determined by the available processors in the parallel platform. To avoid the formation of large interface equations, smaller interface equations are distributed to processors while substructure contributions are performed. This saves a lot of memory storage and computational effort. Direct solution techniques are used for the solution of interface and substructure equation systems. The program is investigated through some example problems. The example problems exposed the need for solving large-scale problems in order to reach better results. The results of the example problems demonstrated the benefits of the parallel SSI algorithm. 相似文献
8.
Accurate prediction of the liquefaction of saturated soils is based on strong coupling between the pore fluid phase and soil skeleton. A practical numerical method for large strain dynamic analysis of saturated soils is presented. The u–p formulation is used for the governing equations that describe the coupled problem in terms of soil skeleton displacement and excess pore pressure. A mixed finite element and finite difference scheme related to large strain analysis of saturated soils based on the updated Lagrangian method is given. The equilibrium equation of fluid-saturated soils is spatially discretized by the finite element method, whereas terms associated with excess pore pressure in the continuity equation are spatially discretized by the finite difference method. An effective cyclic elasto-plastic constitutive model is adopted to simulate the non-linear behavior of saturated soils under dynamic loading. Several numerical examples that include a saturated soil column and caisson-type quay wall are presented to verify the accuracy of the method and its usefulness and applicability to solutions of large strain liquefaction analysis of saturated soils in practical problems. 相似文献
9.
Eduardo Kausel 《Soil Dynamics and Earthquake Engineering》2010,30(9):822-832
Soil–structure interaction is an interdisciplinary field of endeavor which lies at the intersection of soil and structural mechanics, soil and structural dynamics, earthquake engineering, geophysics and geomechanics, material science, computational and numerical methods, and diverse other technical disciplines. Its origins trace back to the late 19th century, evolved and matured gradually in the ensuing decades and during the first half of the 20th century, and progressed rapidly in the second half stimulated mainly by the needs of the nuclear power and offshore industries, by the debut of powerful computers and simulation tools such as finite elements, and by the needs for improvements in seismic safety. The pages that follow provide a concise review of some of the leading developments that paved the way for the state of the art as it is known today. Inasmuch as static foundation stiffnesses are also widely used in engineering analyses and code formulas for SSI effects, this work includes a brief survey of such static solutions. 相似文献
10.
Earthquake geotechnical engineering has been recognised as an important branch of earthquake engineering. The analysis of soil–structure interaction may also be crucial when structural design problems are involved. Soil–structure interaction is a complex problem and needs to be analysed by physical and numerical modelling. Two physical models, consisting of a shallow foundation resting on a sand deposit, are tested on a shaking table to analyse soil–foundation interaction. The physical models are monitored, recording the time-histories of accelerations and displacements in the soil deposit and on the foundation. FEM codes are then employed to numerically model the resulting behaviour, using specific constitutive models and a new hand-made code based on the characteristic-line method. Simplified analytical approaches, still preferred in engineering, are discussed and developed. A comparison is made between the numerical and analytical results and they are also compared with the experimental results to validate the numerical modelling and analytical approaches and, in the new light of the Performance-Based-Design, evaluate their ability to predict foundation displacements (SLE) and bearing capacity (SLU). Finally, interesting aspects regarding the seismic behaviour of the shallow foundation on the sand deposit have been observed and noted. 相似文献
11.
M. Pastor Tongchun Li J.A.Fernández Merodo 《Soil Dynamics and Earthquake Engineering》1997,16(3):161-171
Simple Finite Element models for soil dynamics and earthquake engineering problems in the frequency domain are a fast and valuable tool providing a first approximation before a full non-linear analysis in the time domain is performed.Quite often the problem concerns saturated soils with very small permeability and pore fluid of neglectable compressibility. In the limit, the permeability is assumed to be zero and the pore fluid incompressible. Here, engineers use standard finite element codes formulated in terms of displacements but incompressibility may result in volumetric locking of the mesh with a severe loss of accuracy.The purpose of this paper is to present a simple mixed finite element formulation in the frequency domain based on displacements and pore pressures as main variables. A suitable stabilization technique allowing for equal order interpolation of displacements and pressures has been introduced for incompressible and zero permeability limits.Of course, the range of application is limited to those problems in which the behaviour of the material can be approximated by linear models, and therefore modelling of phenomena such as liquefaction, cyclic mobility or cavitation occur is excluded.The paper shows as well an extremely simple way of coupling solid and water domains as it occurs for instance in quay walls under dynamic loading. 相似文献
12.
Soil–structure interaction problems are typically modelled by assuming subgrade behaviour to be either elastic or viscoelastic. Herein, compliance functions that may be used to solve soil–structure interaction problems are evaluated by treating the subgrade as a liquid-saturated poroelastic material whose behaviour is governed by Biot's theory. The compliances are evaluated for the harmonic rocking and vertical motions of rigid permeable and impermeable plates bearing on a poroelastic halfspace. Comparisons are made with elastic solutions which assume the subgrade to be either completely drained or undrained. Also, solid and fluid contact stresses are reported for the poroelastic case and compared to the solid contact stresses for the elastic cases. 相似文献
13.
A frequency‐dependent and intensity‐dependent macroelement for reduced order seismic analysis of soil‐structure interacting systems 
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下载免费PDF全文 The computational demand of the soil‐structure interaction analysis for the design and assessment of structures, as well as for the evaluation of their life‐cycle cost and risk exposure, has led the civil engineering community to the development of a variety of methods toward the model order reduction of the coupled soil‐structure dynamic system in earthquake regions. Different approaches have been proposed in the past as computationally efficient alternatives to the conventional finite element model simulation of the complete soil‐structure domain, such as the nonlinear lumped spring, the macroelement method, and the substructure partition method. Yet no approach was capable of capturing simultaneously the frequency‐dependent dynamic properties along with the nonlinear behavior of the condensed segment of the overall soil‐structure system under strong earthquake ground motion, thus generating an imbalance between the modeling refinement achieved for the soil and the structure. To this end, a dual frequency‐dependent and intensity‐dependent expansion of the lumped parameter modeling method is proposed in the current paper, materialized through a multiobjective algorithm, capable of closely approximating the behavior of the nonlinear dynamic system of the condensed segment. This is essentially the extension of an established methodology, also developed by the authors, in the inelastic domain. The efficiency of the proposed methodology is validated for the case of a bridge foundation system, wherein the seismic response is comparatively assessed for both the proposed method and the detailed finite element model. The above expansion is deemed a computationally efficient and reliable method for simultaneously considering the frequency and amplitude dependence of soil‐foundation systems in the framework of nonlinear seismic analysis of soil‐structure interaction systems. 相似文献
14.
A novel numerical model based on solid deformation is presented in this paper. This thermo-mechanical model can simulate the tectonic evolution of crust and (lithospheric and asthenospheric) mantle under different conditions. Our implementation uses the finite element method (FEM) in order to solve the equations. As a Lagrangian approach is employed, remeshing techniques are implemented to avoid distortion problems when a certain deformation threshold is reached. The translation of the state between the old and new mesh is achieved by means of the information stored on Lagrangian particles, which minimizes the diffusion. The model is able to represent elastic, viscous and plastic behaviour inside the studied domain. Three types of creep mechanism (diffusion, dislocation and Peierls) are included. Two different quadrilateral isoparametric elements were implemented and can be employed to perform the calculations. The first one is an element with 4 nodes, selective reduced integration and a stabilization operator to diminish hourglass modes, which reduces the computational time needed. The second one has 8 nodes located in standard positions, uses full integration scheme and has no hourglass modes as it satisfies the Inf-Sup condition. Several test cases with known solutions were run to validate the different aspects of the implementation. 相似文献
15.
Smoothed particle hydrodynamics(SPH) is a mesh-free adaptive Lagrangian particle method with attractive features for dealing with the free surface flow.This paper applies the SPH method to simulate the large-amplitude lateral sloshing both with and without a floating body,and the vertical parametrically-excited sloshing in a two-dimensional tank.The numerical results show that the SPH approach has an obvious advantage over conventional mesh-based methods in handling nonlinear sloshing problems such as violent fluid-solid interaction,and flow separation and wave-breaking on the free fluid surface.The SPH method provides a new alternative and an effective way to solve these special strong nonlinear sloshing problems. 相似文献
16.
玻璃钢夹砂管在土木水利工程领域得到了愈来愈广泛的应用,但现有的埋地管道地震响应分析模型大多不考虑管-土动力相互作用,且多针对均质材料管道,无法应用于具有明显层状复合材料结构特征的玻璃钢夹砂管。基于玻璃钢夹砂管的层状复合材料结构特征,建立了完整的埋地玻璃钢夹砂管地震响应分析模型,在数值分析模型中,考虑了管-土间复杂的动力相互作用,以及地震散射波从有限域向无限域的传播。算例分析表明,所建立的埋地玻璃钢夹砂管地震响应分析模型可合理地分析埋地玻璃钢夹砂管在地震荷载作用下的动力响应。 相似文献
17.
Out-of-plane (SH) soil-structure interaction: a shear wall with rigid and flexible ring foundation 下载免费PDF全文
下载免费PDF全文 Soil-structure interaction (SSI) of a building and shear wall above a foundation in an elastic half-space has long been an important research subject for earthquake engineers and strong-motion seismologists. Numerous papers have been published since the early 1970s; however, very few of these papers have analytic closed-form solutions available. The soil-structure interaction problem is one of the most classic problems connecting the two disciplines of earthquake engineering and civil engineering. The interaction effect represents the mechanism of energy transfer and dissipation among the elements of the dynamic system, namely the soil subgrade, foundation, and superstructure. This interaction effect is important across many structure, foundation, and subgrade types but is most pronounced when a rigid superstructure is founded on a relatively soft lower foundation and subgrade. This effect may only be ignored when the subgrade is much harder than a flexible superstructure: for instance a flexible moment frame superstructure founded on a thin compacted soil layer on top of very stiff bedrock below. This paper will study the interaction effect of the subgrade and the superstructure. The analytical solution of the interaction of a shear wall, flexible-rigid foundation, and an elastic half-space is derived for incident SH waves with various angles of incidence. It found that the flexible ring (soft layer) cannot be used as an isolation mechanism to decouple a superstructure from its substructure resting on a shaking half-space. 相似文献
18.
A stream tube integration method is introduced to solve transient subsurface fluid flow problems. The method combines a geometry-embedded form of Darcy's Law and the notion of location of average. Two types of problems, transient radial flow to a well of finite radius in an areally infinite aquifer and in a double porosity system, are solved by the stream tube integration method and the integral finite difference method. Results of the solutions show that the stream tube integration method, with fixed coarse mesh, are more accurate and better behaved than the integral finite difference method, with fine mesh. The fixed mesh stream tube integration method is readily extended to the moving mesh method. With much coarse mesh, the moving mesh technique can obtain the same accurate results as the fixed mesh stream tube integration method. It is suggested that the stream tube integration method is a viable way to state, solve, interpret and verify numerical solutions. The method provides efficient computation and improved accuracy for analysing subsurface fluid flow. © 1998 John Wiley & Sons, Ltd. 相似文献
19.
For a class of civil engineering structures, that can be accurately represented by ‘coupled shear walls’ (CSWs), a discrete model for the analysis of the dynamic interaction with the underlying soil is proposed. The CSWs, with one or more rows of openings, rest on a rigid foundation embedded in the elastic or viscoelastic half-space. A hierarchical finite element model based on an equivalent continuum approach is adopted for the structure. A frequency-domain boundary element method is used to represent the half-space. Finally, the set of equations governing the response of the coupled soil-structure system to harmonic lateral loads acting on the structure is also given. The frequency deviation effect with respect to the fixed-base structure and the effects of radiation and material damping in the soil are presented for different characteristics of the structure and different soil properties. 相似文献
20.
This paper investigates the effects of foundation embedment on the seismic behavior of fluid-elevated tank-foundation–soil system with a structural frame supporting the fluid containing tank. Six different soil types defined in the well-known seismic codes were considered. Both the sloshing effects of the fluid and soil-structure interaction of the elevated tanks located on these six different soils were included in the analyses. Fluid-elevated tank-foundation–soil systems were modeled with the finite element (FE) technique. The fluid-structure interaction was taken into account using Lagrangian fluid FE approximation implemented in the general purpose structural analysis computer program, ANSYS. FE model with viscous boundary was used to include elevated tank-foundation–soil interaction effects. The models were analyzed for the foundations with and without embedment. It was found that the tank roof displacements were affected significantly by the embedment in soft soil, however, this effect was smaller for stiff soil types. Except for soft soil types, embedment did not affect the other response parameters, such as sloshing displacement, of the systems considered in this study. 相似文献