• Title/Summary/Keyword: Soil mechanics

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Modeling of coupled THMC processes in porous media

  • Kowalsky, Ursula;Bente, Sonja;Dinkler, Dieter
    • Coupled systems mechanics
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    • v.3 no.1
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    • pp.27-52
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    • 2014
  • For landfill monitoring and aftercare, long-term prognoses of emission and deformation behaviour are required. Landfills may be considered as heterogeneous porous soil-like structures, in which flow and transport processes of gases and liquids interact with local material degradation and mechanical deformation of the solid skeleton. Therefore, in the framework of continuous porous media mechanics a model is developed that permits the investigation of coupled mechanical, hydraulical and biochemical processes in municipal solid waste landfills.

Experimental study of a modeled building frame supported by pile groups embedded in cohesionless soil

  • Ravi Kumar Reddy, C.;Gunneswara Rao, T.D.
    • Interaction and multiscale mechanics
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    • v.4 no.4
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    • pp.321-336
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    • 2011
  • This paper presents the results of static vertical load tests carried out on a model building frame supported by pile groups embedded in cohesionless soil (sand). The effect of soil interaction on displacements and rotation at the column base and also the shears and bending moments in the columns of the building frame were investigated. The experimental results have been compared with those obtained from the finite element analysis and conventional method of analysis. Soil nonlinearity in the lateral direction is characterized by the p-y curves and in the axial direction by nonlinear vertical springs along the length of the piles (${\tau}-z$ curves) at their tips (Q-z curves). The results reveal that the conventional method gives the shear force in the column by about 40-60%, the bending moment at the column top about 20-30% and at the column base about 75-100% more than those from the experimental results. The response of the frame from the experimental results is in good agreement with that obtained by the nonlinear finite element analysis.

Transient soil-structure interaction with consistent description of radiation damping

  • Zulkifli, Ediansjah;Ruge, Peter
    • Structural Engineering and Mechanics
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    • v.33 no.1
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    • pp.47-66
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    • 2009
  • Radiation damping due to wave propagation in unbounded domains may cause a significant reduction of structural vibrations when excited near resonance. Here a novel matrix-valued algebraic Pad$\acute{e}$-like stiffness formulation in the frequency-domain and a corresponding state equation in the time domain are elaborated for a soil-structure interaction problem with a layered soil excited in a transient manner by a flexible rotor during startup and shutdown. The contribution of radiation damping caused by a soil-layer upon a rigid bedrock is characterized by the corresponding amount of critical damping as it is used in structural dynamics.

Inelastic transient analysis of piles in nonhomogeneous soil

  • Kucukarslan, S.;Banerjee, P.K.
    • Structural Engineering and Mechanics
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    • v.26 no.5
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    • pp.545-556
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    • 2007
  • In this paper, a hybrid boundary element technique is implemented to analyze nonlinear transient pile soil interaction in Gibson type nonhomeogenous soil. Inelastic modeling of soil media is presented by introducing a rational approximation to the continuum with nonlinear interface springs along the piles. Modified $\ddot{O}$zdemir's nonlinear model is implemented and systems of equations are coupled at interfaces for piles and pile groups. Linear beam column finite elements are used to model the piles and the resulting governing equations are solved using an implicit integration scheme. By enforcing displacement equilibrium conditions at each time step, a system of equations is generated which yields the solution. A numerical example is performed to investigate the effects of nonlinearity on the pile soil interaction.

A simplified procedure to incorporate soil non-linearity in missile penetration problems

  • Siddiqui, N.A.;Kumar, S.;Khan, M.A.;Abbas, H.
    • Structural Engineering and Mechanics
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    • v.23 no.3
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    • pp.249-262
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    • 2006
  • In this paper, a simplified mathematical procedure is presented to incorporate nonlinearity in soil material to predict the deceleration time history, penetration depth and other relevant parameters for normal impact of missiles into soil targets. Numerical method is employed for these predictions. The results of the study are compared with experimental observations and predictions available in the literature. A good agreement is found with experimental observations and an improvement is observed with existing predictions. A comparison is also made with linear soil model. Some parametric studies are also carried out to obtain the results of practical interest.

A study on nonlinear seismic response analysis of building considering frequency dependent soil impedance in time domain

  • Nakamura, Naohiro
    • Interaction and multiscale mechanics
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    • v.2 no.1
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    • pp.91-107
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    • 2009
  • In order to accurately estimate the seismic behavior of buildings, it is important to consider both nonlinear characteristics of the buildings and the frequency dependency of the soil impedance. Therefore, transform methods of the soil impedance in the frequency domain to the impulse response in the time domain are needed because the nonlinear analysis can not be carried out in the frequency domain. The author has proposed practical transform methods. In this paper, seismic response analyses considering frequency dependent soil impedance in the time domain are shown. First, the formulation of the proposed transform methods is described. Then, the linear and nonlinear earthquake response analyses of a building on 2-layered soil were carried out using the transformed impulse responses. Through these analyses, the validity and efficiency of the methods were confirmed.

Soil-pile interaction effects in wharf structures under lateral loads

  • Doran, Bilge;Seckin, Aytug
    • Structural Engineering and Mechanics
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    • v.51 no.2
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    • pp.267-276
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    • 2014
  • Wharfs are essential to shipping and support very large gravity loads on both a short-term and long-term basis which cause quite large seismic internal forces. Therefore, these structures are vulnerable to seismic activities. As they are supported on vertical and/or batter piles, soil-pile interaction effects under earthquake events have a great importance in seismic resistance which is not yet fully understood. Seismic design codes have become more stringent and suggest the use of new design methods, such as Performance Based Design principles. According to Turkish Code for Coastal and Port Structures (TCCS 2008), the interaction between soil and pile should somehow be considered in the nonlinear analysis in an accurate manner. This study aims to explore the lateral load carrying capacity of recently designed wharf structures considering soil-pile interaction effects for different soil conditions. For this purpose, nonlinear structure analysis according to TCCS (2008) has been performed comparing simplified and detailed modeling results.

Soil structure interaction effects on structural parameters for stiffness degrading systems built on soft soil sites

  • Aydemir, Muberra Eser
    • Structural Engineering and Mechanics
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    • v.45 no.5
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    • pp.655-676
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    • 2013
  • In this study, strength reduction factors and inelastic displacement ratios are investigated for SDOF systems with period range of 0.1-3.0 s considering soil structure interaction for earthquake motions recorded on soft soil. The effect of stiffness degradation on strength reduction factors and inelastic displacement ratios is investigated. The modified-Clough model is used to represent structures that exhibit significant stiffness degradation when subjected to reverse cyclic loading and the elastoplastic model is used to represent non-degrading structures. The effect of negative strain - hardening on the inelastic displacement and strength of structures is also investigated. Soil structure interacting systems are modeled and analyzed with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. New equations are proposed for strength reduction factor and inelastic displacement ratio of interacting system as a function of structural period($\tilde{T}$, T) ductility (${\mu}$) and period lengthening ratio ($\tilde{T}$/T).

A study on the topographical and geotechnical effects in 2-D soil-structure interaction analysis under ground motion

  • Duzgun, Oguz Akin;Budak, Ahmet
    • Structural Engineering and Mechanics
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    • v.40 no.6
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    • pp.829-845
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    • 2011
  • This paper evaluates the effects of topographical and geotechnical irregularities on the dynamic response of the 2-D soil-structure systems under ground motion by coupling finite and infinite elements. A numerical procedure is employed, and a parametric study is carried out for single-faced slope topographies. It is concluded that topographic conditions may have important effects on the ground motion along the slope. The geotechnical properties of the soil will also have significantly amplified effects on the whole system motion, which cannot be neglected for design purposes. So, dynamic response of a soil-structure systems are primarily affected by surface shapes and geotechnical properties of the soil. Location of the structure is another parameter affecting the whole system response.

Analysis of circular plates on two - parameter elastic foundation

  • Saygun, Ahmet;Celik, Mecit
    • Structural Engineering and Mechanics
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    • v.15 no.2
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    • pp.249-267
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    • 2003
  • In this study, circular plates subjected to general type of loads and supported on a two-parameter elastic foundation are analysed. The stiffness, elastic bedding and soil shear effect matrices of a fully compatible ring sector plate element, developed by Saygun (1974), are obtained numerically assuming variable thickness of the element. Ring sector soil finite element is also defined to determine the deflection of the soil surface outside the domain of the plate in order to establish the interaction between the plate and the soil. According to Vallabhan and Das (1991) the elastic bedding (C) and shear parameters ($C_T$) of the foundation are expressed depending on the elastic constants ($E_s$, $V_s$) and the thickness of compressible soil layer ($H_s$) and they are calculated with a suitable iterative procedure. Using ring sector elements presented in this paper, permits the generalization of the loading and the boundary conditions of the soil outside the plate.