• Title, Summary, Keyword: inelasticity

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Analytical study on the influence of distributed beam vertical loading on seismic response of frame structures

  • Mergos, P.E.;Kappos, A.J.
    • Earthquakes and Structures
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    • v.5 no.2
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    • pp.239-259
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    • 2013
  • Typically, beams that form part of structural systems are subjected to vertical distributed loading along their length. Distributed loading affects moment and shear distribution, and consequently spread of inelasticity, along the beam length. However, the finite element models developed so far for seismic analysis of frame structures either ignore the effect of vertical distributed loading on spread of inelasticity or consider it in an approximate manner. In this paper, a beam-type finite element is developed, which is capable of considering accurately the effect of uniform distributed loading on spreading of inelastic deformations along the beam length. The proposed model consists of two gradual spread inelasticity sub-elements accounting explicitly for inelastic flexural and shear response. Following this approach, the effect of distributed loading on spreading of inelastic flexural and shear deformations is properly taken into account. The finite element is implemented in the seismic analysis of plane frame structures with beam members controlled either by flexure or shear. It is shown that to obtain accurate results the influence of distributed beam loading on spreading of inelastic deformations should be taken into account in the inelastic seismic analysis of frame structures.

Simplified model for analysis of soil-foundation system under cyclic pushover loading

  • Kada, Ouassila;Benamar, Ahmed;Tahakourt, Abdelkader
    • Structural Engineering and Mechanics
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    • v.67 no.3
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    • pp.267-275
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    • 2018
  • A numerical study of soil-foundation system under monotonic and cyclic pushover loading is conducted, taking into account both material and geometric nonlinearities. A complete and refined 3D finite element (FE) model, using contact condition and allowing separation between soil and foundation, is implemented and used in order to evaluate the nonlinear relationship between applied vertical forces and induced settlements. Based on the obtained curve, a simplified model is proposed, in which the soil inelasticity is satisfactorily represented by two vertical springs with trilinear behavior law, and the foundation uplifting is insured by gap elements. Results from modeling soil-foundation system supporting a bridge pier have shown that the simplified model is able to capture irreversible settlements induced by cyclic rocking, due to soil inelasticity and vertical loading, as well as large rotations due to foundation uplifting.

Assessing the effect of inherent nonlinearities in the analysis and design of a low-rise base isolated steel building

  • Varnavaa, Varnavas;Komodromos, Petros
    • Earthquakes and Structures
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    • v.5 no.5
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    • pp.499-526
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    • 2013
  • Seismic isolation is an effective method for the protection of buildings and their contents during strong earthquakes. This research work aims to assess the appropriateness of the linear and nonlinear models that can be used in the analysis of typical low-rise base isolated steel buildings, taking into account the inherent nonlinearities of the isolation system as well as the potential nonlinearities of the superstructure in case of strong ground motions. The accuracy of the linearization of the isolator properties according to Eurocode 8 is evaluated comparatively with the corresponding response that can be obtained through the nonlinear hysteretic Bouc-Wen constitutive model. The suitability of the linearized model in the determination of the size of the required seismic gap is assessed, under various earthquake intensities, considering relevant methods that are provided by building codes. Furthermore, the validity of the common assumption of elastic behavior for the superstructure is explored and the alteration of the structural response due to the inelastic deformations of the superstructure as a consequence of potential collision to the restraining moat wall is studied. The usage of a nonlinear model for the isolation system is found to be necessary in order to achieve a sufficiently accurate assessment of the structural response and a reliable estimation of the required width of the provided seismic gap. Moreover, the simulations reveal that the superstructure's inelasticity should be taken into account, especially if the response of the structure under high magnitude earthquakes is investigated. The consideration of the inelasticity of the superstructure is also recommended in studies of structural collision of seismically isolated structures to the surrounding moat wall, since it affects the response.

Evaluation of Seismic Performance for Bridge Structure Using Capacity Spectrum Method (역량스펙트럼법을 이용한 교량의 내진성능평가)

  • 이창수;김승익;김현겸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.75-80
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    • 2000
  • Evaluation method of seismic performance has mainly used elastic spectrum analysis. This method has simplicity of analysis but deficiency of accuracy. And evaluation method of seismic performance using inelastic dynamic analysis reflects accurately inelasticity of material but hardly reflects site effects. This study suggested evaluation scheme of seismic performance for bridge structure using capacity spectrum method applied inelastic static analysis and standard design response spectrum of Korea Standard Specification for Highway Bridge. Two results, capacity spectrum method and inelastic dynamic analysis method, are very similar. As a result, this study appropriately supply both simplicity of analysis and accuracy of result.

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Coupling non-matching finite element discretizations in small-deformation inelasticity: Numerical integration of interface variables

  • Amaireh, Layla K.;Haikal, Ghadir
    • Coupled systems mechanics
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    • v.8 no.1
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    • pp.71-93
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    • 2019
  • Finite element simulations of solid mechanics problems often involve the use of Non-Confirming Meshes (NCM) to increase accuracy in capturing nonlinear behavior, including damage and plasticity, in part of a solid domain without an undue increase in computational costs. In the presence of material nonlinearity and plasticity, higher-order variables are often needed to capture nonlinear behavior and material history on non-conforming interfaces. The most popular formulations for coupling non-conforming meshes are dual methods that involve the interpolation of a traction field on the interface. These methods are subject to the Ladyzhenskaya-Babuska-Brezzi (LBB) stability condition, and are therefore limited in their implementation with the higher-order elements needed to capture nonlinear material behavior. Alternatively, the enriched discontinuous Galerkin approach (EDGA) (Haikal and Hjelmstad 2010) is a primal method that provides higher order kinematic fields on the interface, and in which interface tractions are computed from local finite element estimates, therefore facilitating its implementation with nonlinear material models. The inclusion of higher-order interface variables, however, presents the issue of preserving material history at integration points when a increase in integration order is needed. In this study, the enriched discontinuous Galerkin approach (EDGA) is extended to the case of small-deformation plasticity. An interface-driven Gauss-Kronrod integration rule is proposed to enable adaptive enrichment on the interface while preserving history-dependent material data at existing integration points. The method is implemented using classical J2 plasticity theory as well as the pressure-dependent Drucker-Prager material model. We show that an efficient treatment of interface variables can improve algorithmic performance and provide a consistent approach for coupling non-conforming meshes in inelasticity.

Calculation of granular flow with DEM(Discrete Element Method) (DEM(Discrete Element Method)를 사용한 분체 유동해석)

  • Choi J. W.;Sah J. Y.
    • 한국전산유체공학회:학술대회논문집
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    • pp.197-203
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    • 1998
  • The discrete element method is a numerical model capable of describing the mechanical behaviour of assemblies of discs and spheres. The method is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the particles modelled particle by particle. In this paper, A two-dimensional model for computing contacts and motions of granular particles of unform, inelasticity is presented. And, code is developed. The primary aim of this paper is to approv computational result of continuum alaysis which is on processing. The end of this paper, that code is tested with several examples.

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A Nonlinear Finite Element Analysis of Hybrid Coupled Shear Wall Connections governed Panel Shear Failure (패널 전단파괴형 복합 병렬 전단벽 접합부의 비선형 유한요소해석)

  • Han Min Ki;Kim Sun Woo;Park Wan Shin;Yun Hyun Do
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.175-178
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    • 2005
  • The major object of this paper is to propose a nonlinear finite element analysis(FEA) technique of steel coupling beams-wall connections governed panel shear failure using ABAQUS. Detailed finite element models are created by studying the monotonic load response of the designed steel coupling beams-wall connections. The developed models account for the effect of material inelasticity, concrete cracking, panel shear failure and geometric nonlinearity. In order to verify the proposed FEA model, this study attended experiment considered parameters to the steel beam : face bearing plates, and horizontal ties. And the analytical result attended by the proposed FEA model validated through comparisons with the experimental results. Finally, the study estimated the analytical values compared with ASCE Design Guidelines. At this time, the analysis showed good agreement between the theoretical and experimental results.

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A Nonlinear Finite Element Analysis to Reinforced Concrete Frame Retrofitted with Cast-In Plate Infilled Shear Wall (현장끼움벽으로 보강된 철근콘크리트 골조의 비선형 유한요소해석)

  • Han Min Ki;Lee Hye Yeon;Kim Hyo Jin;Lee Kab Weon;Choi Chang Sik;Yun Hyun Do
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.73-76
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    • 2005
  • This paper discussed finite element method(FEM) models of the reinforced concrete frame retrofitted with cast-in plate infilled shear wall and analysed under constant axial and monotonic lateral load using ABAQUS. Detailed finite element models are created by studying the monotonic load response of the designed connection of reinforced concrete frame and cast-in plate infilled shear wall. The developed models account for the effect of material inelasticity, concrete cracking, geometric nonlinearity and bond-slip of steel, frame and infilled shear wall. In order to verify the proposed FEM, this study behaved analysis considered a diagonal reinforced steel. The analytical results compared with the experimental results.

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Analysis and design for stability in the U.S. - An overview

  • Lui, Eric M.;Ge, Ma
    • Steel and Composite Structures
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    • v.5 no.2_3
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    • pp.103-126
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    • 2005
  • This paper describes the theoretical background and underlying principles behind the American Institute of Steel Construction Load and Resistance Factor Design (AISC LRFD) Specification for the analysis and stability design of steel frames. Various analysis procedures that can take into consideration the effects of member instability, frame instability, member-frame interaction, geometric imperfections, and inelasticity are reviewed. Design approaches by which these factors can be incorporated in the design of steel moment frames are addressed. Current specification guidelines for member and frame design in the U.S. are summarized. Examples are given to illustrate the validity of the design equations. Some future directions for the analysis and stability design of steel frames are discussed.

Inelastic distortional buckling of cantilevers

  • Lee, Dong-Sik;Bradford, Mark Andrew
    • Steel and Composite Structures
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    • v.3 no.1
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    • pp.1-12
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    • 2003
  • Cantilevers are unique statically determinate structural elements with respect to their mode of overall buckling, in that the tension flange is the critical flange under gravity loading, and is the flange that deflects greatest during overall buckling. While this phenomenon does not complicate the calculation of the lateral buckling load, either theoretically or in structural design codes, it has been shown in previous research that the influence of distortion in the elastic buckling of cantilevers is not the same as that experienced in the elastic buckling of simply supported beams. This paper extends the study of the distortional buckling of cantilevers into the hitherto unconsidered inelastic range of structural response. A finite element method for studying the inelastic bifurcative instability of members whose cross-sections may distort during buckling is described, and the efficacy of the method is demonstrated. It is then used to study the inelastic distortional buckling of hot-rolled I-section cantilevers with two common patterns of residual stresses, and which may be restrained elastically from buckling by other structural elements.