• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.229-233
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• 2003

This paper describes a practical formulation of Non-Bernoulli-Compatibility Truss Model. Not only equilibrium conditions but also some approximations are employed to solve for the unknowns included in the proposed model. By assuming that the ratio of $V_a$ to V remains to be constant along the shear span, the relationship between $\alpha$ and z is mathematically established as an arch shape function. $V_m$ is also approximated to be an empirical value that is equal to the least membrane shear strength. The coefficient a is made utilizing a nonlinear finite element analysis. The adequacy of the model is examined by test results available in literatures, and the predicted values are shown to be in excellent agreement with the experimental results.

• Structural Engineering and Mechanics
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• 제38권5호
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• pp.593-618
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• 2011

This paper deals with the problem of the determination of the response of a viscoelastic Bernoulli-Navier beam, which is resting on an elastic medium. Assuming uniaxial bending, the displacement of the beam axis is governed by an integro-differential equation. The compatibility of the displacements between the beam and the elastic medium is imposed through an integral equation. In general and in particular in the case of a Boussinesq medium, the solution has to be pursued numerically. On the contrary, in the case of a Winkler's medium the compatibility equation becomes a linear finite relationship, which allows finding an original analytical solution of the problem for both hereditary and aging behavior of the beam. Some numerical examples complete the paper, in which a comparison is made between the hereditary and the aging model for the creep of the beam.

• Structural Engineering and Mechanics
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• 제2권1호
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• pp.1-16
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• 1994

A unified theory has recently been developed for reinforced concrete structures (Hsu 1993), subjected to the four basic actions - bending, axial load, shear and torsion. The theory has five components, namely, the struts-and-ties model, the equilibrium (or plasticity) truss model, the Bernoulli compatibility truss model, the Mohr compatibility truss model and the softened truss model. Because the last three models can satisfy the stress equilibrium, the strain compatibility and the constitutive laws of materials, they can predict not only the strength, but also the load-deformation history of a member. In this paper the five models are summarized to illustrate their intrinsic consistency.

• 콘크리트학회논문집
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• 제18권3호
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• pp.379-388
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• 2006

본 연구의 목적은 휨과 전단에 지배 받는 철근콘크리트 보에서 아치작용에 의한 전단기여분을 평가하는 모델을 개발하는 것이다. 전단력은 휨모멘트의 변화률이라는 관계식을 기초로, 분산트러스 이상화 기법을 이용하여 횡단면에서 베르누이(Bernoulli) 휨 평면으로부터 전단변형적합조건을 새롭게 유도하였다. MCFT와 분산트러스 이상화를 통해 전단흐름에 의한 복부전단요소의 전단곡률을 일치시키는 전단변형적합조건을 수립하였다. 전단변형적합조건을 이용하면, 보 전단거동은 타이드아치작용과 보 작용의 두 성분으로 수치적 분해 될 수 있다. 그리고 두 기본 작용의 분해가 가능하기 때문에 전단에 지배받는 보의 내력을 예측할 수 있다. 제안 모델의 유효성은 기존 문헌에 수록된 활용 가능한 실험 자료를 통해 검증하였고, 수행 결과는 예측치와 실험치 사이에서 실질적으로 일치하는 결과를 얻었다. 결과의 정확성으로부터 제안 모델의 합리성을 확신할 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.362-365
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• 2006

This paper presents a model for evaluating the contribution by arch action to shear resistance in shear-critical RC beams. Based on the relationship between shear and bending moment in beams subjected to combined shear and bending, The behavior of a beam is explicitly divided into two base components of the flexural action and the tied arch action. The compatibility condition of the shear deformation that deviates from Bernoulli bending plane is formulated utilizing the smeared truss idealization with an inclined compression chord. From this shear compatibility condition in a beam, the shear contribution by the arch action is numerically decoupled.

• Structural Engineering and Mechanics
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• 제72권2호
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• pp.217-227
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• 2019

The methodology known as "shape sensing" allows the reconstruction of the displacement field of a structure starting from strain measurements, with considerable implications for structural monitoring, as well as for the control and implementation of smart structures. An approach to shape sensing is based on the inverse Finite Element Method (iFEM) that uses a variational principle enforcing a least-squares compatibility between measured and analytical strain measures. The structural response is reconstructed without the knowledge of the mechanical properties and load conditions but based only on the relationship between displacements and strains. In order to efficiently apply iFEM to the most common structural typologies of civil engineering, its formulation according to the kinematical assumptions of the Bernoulli-Euler theory is presented. Two beam inverse finite elements are formulated for different loading conditions. Depending on the type of element, the relationship between the minimum number of required measurement stations and the interpolation order is defined. Several examples representing common applications of civil engineering and involving beams and frames are presented. To simulate the experimental strain data at the station points and to verify the accuracy of the displacements obtained with the iFEM shape sensing procedure, a direct FEM analysis of the considered structures is performed using the LUSAS software.

• 콘크리트학회논문집
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• 제18권6호
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• pp.819-825
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• 2006

본 연구의 목적은 휨과 전단에 지배받는 철근콘크리트 보에서 아치작용에 의한 전단기여성분을 평가하기 위한 새로운 해석 모델의 적용성을 검증하기 위한 것이다. 새로운 모델은 전단력은 휨모멘트의 변화율이라는 관계식을 기초로, 분산트러스 이상화 기법을 이용하여 횡단면에서 베르누이(Bernoulli) 휨 평면으로부터 전단변형적합조건을 새롭게 유도하였으며, MCFT와 분산트러스 이상화를 통해 전단흐름에 의한 복부전단요소의 전단곡률을 일치시키는 전단변형적합조건을 수립하였다. 전단변형적합조건을 이용하면, 보 전단거동은 타이드아치작용과 보작용의 두 성분으로 수치적 분해 될 수 있다. 이러한 분리 접근법의 유효성은 기존 문헌에 수록된 활용 가능한 실험 자료를 통해 검증하였다. 수행 결과 실제 측정 전단강도와 비교하였을 때 복부가 분담하는 전단강도는 훨씬 일정하며, 역학적 복부철근비와 훌륭한 선형 상관관계에 있는 것으로 나타났다. 새로운 해석 모델은 철근콘크리트 부재의 전단 거동에 영향을 미치는 각 변수나 메커니즘을 합리적으로 설명할 수 있는 모델이라고 할 수 있겠다.

• Steel and Composite Structures
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• 제38권3호
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• pp.257-270
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• 2021

This paper presents a displacement-based numerical methodology following the Euler-Bernoulli theory to simulate the 2 nonlinear behavior of steel structures. It is worth emphasizing the adoption of co-rotational finite element formulations considering large displacements and rotations and an inelastic material behavior. The numerical procedures proposed considers plasticity concentrated at the finite elements nodes, and the simulation of the steel nonlinear behavior is approached via the Strain Compatibility Method (SCM), where the material constitutive relation is used explicitly. The SCM is also applied in determining the sections bearing capacity. Moreover, the present numerical approach is not limited to a specific structural member cross-sectional typology, with the residual stress models introduced explicitly in subareas of steel cross-sections generated by a 2D discretization. Finally, results consistent with the literature and with low processing time are presented.

• Advances in Computational Design
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• 제5권4호
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• pp.397-416
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• 2020

Functionally graded material (FGM) illustrates a novel class of composites that consists of a graded pattern of material composition. FGM is engineered to have a continuously varying spatial composition profile. Current work focused on buckling analysis of beam made of stepwise linear and quadratic graded material in axial direction subjected to axial span-load with piecewise function and rested on shear layer based on classical beam theory. The various boundary and natural conditions including simply supported (S-S), pinned - clamped (P-C), axial hinge - pinned (AH-P), axial hinge - clamped (AH-C), pinned - shear hinge (P-SHH), pinned - shear force released (P-SHR), axial hinge - shear force released (AH-SHR) and axial hinge - shear hinge (AH-SHH) are considered. To the best of the author's knowledge, buckling behavior of this kind of Euler-Bernoulli beams has not been studied yet. The equilibrium differential equation is derived by minimizing total potential energy via variational calculus and solved analytically. The boundary conditions, natural conditions and deformation continuity at concentrated load insertion point are expressed in matrix form and nontrivial solution is employed to calculate first buckling loads and corresponding mode shapes. By increasing truncation order, the relative error reduction and convergence of solution are observed. Fast convergence and good compatibility with various conditions are advantages of the proposed method. A MATLAB code is provided in appendix to employ the numerical procedure based on proposed method.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.165-176
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• 2008

In this paper, a new iterative method for solving vehicle-bridge interaction problems is proposed. Iterative methods have advantages over the non-iterative methods in that it is not necessary to update the system matrix for a given wheel location, and the method can be applied for a new type of car or bridge with few or no modifications. In the proposed method, the necessity of system matrices update is eliminated using the equivalent interaction force acting on the bridge, which is obtained iteratively. Ballast stiffness is included in the interaction forces and the geometric compatibility at the contact points are used as convergence criteria. The bridge is considered as an elastic Bernoulli-Euler beam with surface irregularity and ballast stiffness. The moving vehicle is modeled as a multi-axle mass-spring-damper system having many degrees of freedom depending on the number of axles. The pitching effect, which is the interaction effect between the rear and front wheels when a vehicle begins to enter or leave the bridge, is also considered in the formulation including extended ground boundaries having surface irregularity and ballast stiffness. The applicability of the proposed method is illustrated in the numerical studies.