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RISS 인기검색어
- 검색키워드
- 저자 : R. Emre Erkmen (검색결과 6 건)
- 무료
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Elasto-plastic damage modelling of beams and columns with mechanical degradation
R. Emre Erkmen,Nadarajah Gowripalan,Vute Sirivivatnanon 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3
Within the context of continuum mechanics, inelastic behaviours of constitutive responses are usually modelled by using phenomenological approaches. Elasto-plastic damage modelling is extensively used for concrete material in the case of progressive strength and stiffness deterioration. In this paper, a review of the main features of elasto-plastic damage modelling is presented for uniaxial stress-strain relationship. It has been reported in literature that the influence of Alkali-Silica Reaction (ASR) can lead to severe degradations in the modulus of elasticity and compression strength of the concrete material. In order to incorporate the effects of ASR related degradation, in this paper the constitutive model of concrete is based on the coupled damage-plasticity approach where degradation in concrete properties can be captured by adjusting the yield and damage criteria as well as the hardening moduli related parameters within the model. These parameters are adjusted according to results of concrete behaviour from the literature. The effect of ASR on the dynamic behaviour of a beam and a column are illustrated under moving load and cyclic load cases.
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Iterative global-local procedure for the analysis of thin-walled composite laminates
R. Emre Erkmen,Ashkan Afnani 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.3
This paper presents a finite element procedure based on Bridging multi-scale method (BMM) in order to incorporate the effect of local/cross-sectional deformations (e.g., flange local buckling and web crippling) on the global behaviour of thin-walled members made of fibre-reinforced polymer composite laminates. This method allows the application of local shell elements in critical regions of an existing beam-type model. Therefore, it obviates the need for using computationally expensive shell elements in the whole domain of the structure, which is otherwise necessary to capture the effect of the localized behaviour. Consequently, highly accurate analysis results can be achieved with this method by using significantly smaller finite element model, compared to the existing methods. The proposed method can be used for composite polymer laminates with arbitrary fibre orientation directions in different layers of the material, and under various loading conditions. Comparison with full shell-type finite element analysis results are made in order to illustrate the efficiency and accuracy of the proposed technique.
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Iterative global-local approach to consider the local effects in dynamic analysis of beams
Erkmen, R. Emre,Afnani, Ashkan Techno-Press 2017 Coupled systems mechanics Vol.6 No.4
This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis.
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Treatment of locking behaviour for displacement-based finite element analysis of composite beams
Erkmen, R. Emre,Bradford, Mark A.,Crews, Keith Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.1
In the displacement based finite element analysis of composite beams that consist of two Euler-Bernoulli beams juxtaposed with a deformable shear connection, the coupling of the displacement fields may cause oscillations in the interlayer slip field and reduction in optimal convergence rate, known as slip-locking. In this study, the B-bar procedure is proposed to alleviate the locking effects. It is also shown that by changing the primary dependent variables in the mathematical model, to be able to interpolate the interlayer slip field directly, oscillations in the slip field can be completely eliminated. Examples are presented to illustrate the performance and the numerical characteristics of the proposed methods.
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Treatment of locking behaviour for displacement-based finite element analysis of composite beams
R. Emre Erkmen,Mark A. Bradford,Keith Crews 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.1
In the displacement based finite element analysis of composite beams that consist of two Euler-Bernoulli beams juxtaposed with a deformable shear connection, the coupling of the displacement fieldsmay cause oscillations in the interlayer slip field and reduction in optimal convergence rate, known as sliplocking. In this study, the B-bar procedure is proposed to alleviate the locking effects. It is also shown that by changing the primary dependent variables in the mathematical model, to be able to interpolate the interlayer slip field directly, oscillations in the slip field can be completely eliminated. Examples are presented to illustrate the performance and the numerical characteristics of the proposed methods.
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An Efficient Formulation for Thin-walled Beams Curved in Plan
Ashkan Afnani,R. Emre Erkmen,Vida Niki 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.3
An efficient formulation is developed for the elastic analysis of thin-walled beams curved in plan. Using a second-order rotation tensor, the strain values of the deformed configuration are calculated in terms of the displacement values and the initial curvature by adopting the right extensional strain measure. The principle of virtual work is then used to obtain the nonlinear equilibrium equations, based on which a finite element beam formulation is developed. The accuracy of the method is confirmed through comparison with test results, shell finite element formulations and other curved beam formulations from the literature. It is also shown that the results of the developed formulation are very accurate for the cases where initial curvature is large.
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