• Steel and Composite Structures
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• 제29권1호
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• pp.39-51
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• 2018

Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.347-354
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• 2006

In this paper, we work with steel circular tubes and propose analysis model which can consider local buckling that it has an effect on failure of steel structures and induce the relation between loading and deformation. First of all, in respect to axial symmetry local buckling, which is simplest case, elasto-plastic behavior acting only axial loads is object Therefore, it suggests analysis model for axial symmetry local buckling. And that is explainable the process from increasing internal force to decreasing passing maximum internal force. Besides, we induce the relation between the axial force and axial deformation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2059-2065
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• 2008

In this paper, quasi-static crushing tests of composite circular tubes under axial compression load are conducted to investigate the energy absorption characteristics. Circular tubes used for this experiment are glass/epoxy (GFRP) composite tubes, which is fabricated by the filament winding method. One edge of the composite tube is chamfered to reduce the initial peak load and to prevent catastrophic failure during crushing process. Two suggested trigger mechanisms for the composite tubes are investigated. Crushing modes are mainly affected by thickness/diameter ratio, and average crushing loads are mainly affected by their cross-sections. Energy absorption characteristics vary significantly as a function of the tube geometry, trigger mechanism, t/D ratio and the cross-sectional shape.

• 한국공간구조학회논문집
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• 제18권3호
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• pp.117-124
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• 2018

In the post-tensioned concrete member, additional reinforcement is required to prevent failure in the anchorage zone. In this study, the details of reinforcement suitable for the anchorage zone of the post-tensioned concrete member using circular anchorage was proposed based on the experimental results. The tests were conducted with the compressive strength of concrete and reinforcement types as variables. The experimental results indicated that the additional reinforcement for the anchorage zone is required when the compressive strength of concrete is less than 17.5 MPa. U-shaped reinforcement shows most effective performance in terms of maximum strength and cracks patterns.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
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• pp.73-80
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• 2006

In this paper, we work with steel circular tubes and propose analysis model which can consider local buckling that it has an effect on failure of steel structures and induce the relation between loading and deformation. First of all, in respect to axial symmetry local buckling, which is simplest case, elasto-plastic behavior acting only axial loads is object. Therefore, it suggests analysis model for axial symmetry local buckling. And that is explainable the process from increasing internal force to decreasing passing maximum internal force. Besides, we induce the relation between the axial force and axial deformation.

• Advances in materials Research
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• 제5권2호
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• pp.81-92
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• 2016

Stress concentration is an interesting and essential field of study, as it is the prime cause of failure of structural parts under static load. In the current paper, stress and strain concentration factors in unidirectional functionally graded (UDFGM) plate with central circular cutout are predicted by carrying out a finite element study on ANSYS APDL platform. The present study aims to bridge the lacuna in the understandings of stress analysis in perforated functionally graded plates. It is found that the material variation parameter is an important criterion while designing a perforated UDFGM plate. By selecting a proper material variation parameter and direction of material gradation, the stress and strain concentrations can be significantly reduced.

• Geomechanics and Engineering
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• 제15권1호
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• pp.621-630
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• 2018

In the note a comprehensive and optimal passive-active mode for describing the limit failure of circular shallow tunnel with settlement is put forward to predict the catastrophic stability during the geotechnical construction. Since the surrounding soil mass around tunnel roof is not homogeneous, with tools of variation calculus, several different curve functions which depict several failure shapes in different soil layers are obtained using virtual work formulae. By making reference to the simple-form of Power-law failure criteria based on numerous experiments, a numerical procedure with consideration of combination of upper bound theorem and stochastic medium theory is applied to the optimal analysis of shallow-buried tunnel failure. With help of functional catastrophe theory, this work presented a more accurate and optimal failure profile compared with previous work. Lastly the note discusses different effects of parameters in new yield rule and soil mechanical coefficients on failure mechanisms. The scope of failure block becomes smaller with increase of the parameter A and the range of failure soil mass tends to decrease with decrease of unit weight of the soil and tunnel radius, which verifies the geomechanics and practical case in engineering.

• 대한기계학회논문집A
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• 제32권6호
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• pp.496-503
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• 2008

With the improvement of computer power and technology, fracture modelling by finite element methods has become a topic of extensive studies. However, fracture simulation much limited to an academic study of crack propagation with a fine mesh. Element deletion method is a useful tool for estimating damage due to accidental or extreme loads on structures, provided that an effective and realistic criterion is established for simulating the material failure and subsequent element deletion. In this study, ABAQUS/Explicit is used to simulate the material failure on the basis of experimental results by X. Huang et al. Through numerical experiments, we suggest a formulation to determine the failure strain associated with the size and thickness of removed elements.

• Structural Engineering and Mechanics
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• 제77권2호
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• pp.273-291
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• 2021

The strut-and-tie method (STM) has been widely accepted and used as a rational approach for the design of disturbed regions ('D' regions) of reinforced concrete members such as in corbels and deep beams, where traditional flexure theory does not apply. This paper evaluates the applicability of the equilibrium based STM in strength predictions of deep beams (with rectangular and circular cross-section) and corbels using the available experiments in literature. STM is found to give fairly good results for corbel and deep beams. The failure modes of these deep members are also studied, and an optimum amount of distribution reinforcement is suggested to eliminate the premature diagonal splitting failure. A comparison with existing empirical and semi empirical methods also show that STM gives more reliable results. The nonlinear finite element analysis (NLFEA) of 50 deep beams and 20 corbels could capture the complete behaviour of deep members including crack pattern, failure load and failure load accurately.

• 대한토목학회논문집
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• 제26권2A호
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• pp.311-318
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• 2006

GFRP를 이용하여 종방향 철근의 겹침이음이 존재하는 원형RC 교각의 내진보강 성능을 파악하기 위해 5개의 실물규모 실험체를 제작하여 실험하였다. 대상교각은 1979년에 완공된 후 현재 공용중인 비내진 원형 RC교각으로 겹침이음된 종방향 철근의 부착파괴에 의한 급작스런 파괴가 예상된다. GFRP 래핑(Wrapping)으로 보강된 교각들의 내진성능은 매우 향상되었다. 하지만, 예상한 휨파괴는 발생하지 않았고, 종방향 철근은 항복하지 않았다. 보강된 교각의 파괴양상은 겹침이음된 종방향 철근의 지연된 부착파괴로 판단된다. 제안된 GFRP 보강설계법을 실험적으로 검증하였다.