• 대한조선학회논문집
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• 제50권4호
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• pp.255-261
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• 2013

This paper presents prediction of ultimate longitudinal strength of a VLCC, "Energy Concentration" for which many benchmark studies have been carried out, based on kinematic displacement method proposed by Tayyar and Bayraktarkatal (2012). Kinematic displacement theory provides semi-analytical solution of average compressive strengths for various kinds of stiffened panels. The accuracy of average compressive strengths obtained from formulas of CSR(common structural rules) for tankers and kinematic displacement method are discussed in the fore part of this paper. Hull girder ultimate strengths using Smith method are also compared for different average compressive strengths. By comparing them with other benchmark results, it is concluded that the new method provides lower bounds, because hull girder strengths under the sagging and hogging moment conditions approach nearly lower bounds.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.838-849
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• 2017

This paper proposes penalty factor equations that take into consideration the weld strength over-match given in the classified form similar to the revised equations presented in the Code Case N-779 via cyclic elastic-plastic finite element analysis. It was found that the $K_e$ analysis data reflecting elastic follow-up can be consolidated by normalizing the primary-plus-secondary stress intensity ranges excluding the nonlinear thermal stress intensity component, $S_n$ to over-match degree of yield strength, $M_F$. For the effect of over-match on $K_n{\times}K_{\nu}$, dispersion of the $K_n{\times}K_{\nu}$ analysis data can be sharply reduced by dividing total stress intensity range, excluding local thermal stresses, $S_{p-lt}$ by $M_F$. Finally, the proposed equations were applied to the weld between the safe end and the piping of a pressurizer surge nozzle in pressurized water reactors in order to calculate a cumulative usage factor. The cumulative usage factor was then compared with those derived by the previous $K_e$ factor equations. The result shows that application of the proposed equations can significantly reduce conservatism of fatigue assessment using the previous $K_e$ factor equations.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.710-711
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• 2006

High strength PM aluminium alloys Al-Zn-Mg-Cu (7075 type) were studied by using commercially available powder blends and the sinter-forging technique for component production. Principal areas of focus include the response to PM processing, micro structural assessment and material properties of Aluminium sinter forged products. Green preforms are successfully sintered to near full density by solid-supersolidus liquid phase sintering. Sinter forging method can produce components with net shape and mechanical characteristics of the material have improved greatly. Properties of this new PM Al-alloy were found to be reproducible in an industrial production environment.

• Earthquakes and Structures
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• 제16권1호
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• pp.69-82
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• 2019

As the residual displacement and/or drift demands are commonly used for seismic assessment of buildings, the estimation of these values play a very critical role through earthquake design philosophy. The residual displacement estimation of fixed base structures has been the topic of numerous researches up to now, but the effect of soil flexibility is almost always omitted. In this study, residual displacement demands are investigated for SDOF systems with period range of 0.1-3.0 s for near-field and far-field ground motions for both fixed and interacting cases. The elastoplastic model is used to represent non-degrading structures. Based on time history analyses, a new simple yet effective equation is proposed for residual displacement demand of any system whether fixed base or interacting as a function of structural period, lateral strength ratio and spectral displacement.

• 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.

• 전산구조공학
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• 제10권3호
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• pp.133-143
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• 1997

한국에서는 서울-부산간 고속철도건설이 5년전 시험구간의 시공을 시작으로 본격적인 고속철도건설이 진행중에 있다. 본 연구에서는, 고속철도교량의 전산화 유지관리를 위한 신뢰성에 기초한 건전성 평가모델을 개발하는데 중점을 두고 있다. 신뢰성 해석을 위한 PC철도교의 강도한계상태모형은 휨 또는 전단강도와 같이 단일 파괴모드뿐만아니라 휨, 전단 및 비틀림을 동시에 고려하는 조합상관식도 고려되었다. 실제적인 내하력 평가를 위해 체계신뢰성에 기초한 등가내하력 평가방법을 사용하였으며 이로부터 얻은 결과를 요소신뢰성과 재래적인 방법에 의한 결과와 비교하였다. 본 논문에서 제안한 모델은 실재하는 고속철도교량의 신뢰성에 기초한 실제적인 안전도 및 내하력평가를 위한 적절한 모델임을 알 수 있었다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2004년도 추계학술발표회
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• pp.137-141
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• 2004

선체구조는 기본적으로 판부재의 조합으로 이루어져 있으며, 이러한 판부재는 하중분담 능력에 따라서 전체적인 구조의 강도에 른 영향을 미치게 된다. 또한 각 구조적인 판부재는 개별적으로 거동하는 것이 아니라 전체적인 구조와 연속적으로 작용하게 된다. 선박구조물은 강구조물과 해양구조물에서와는 달리 고정도의 부정정 구조물로 구성되어 있으며 이러한 구조물의 거동을 정확하게 규명하기 위해서는 복잡하게 구성되어 있는 선체판넬 구조를 단순화시켜서 해석에 적용하여야 한다. 본 연구에서는 선체판넬구조의 모델링영역에 따른 최종강도 거동의 차이를 분석하여, 가장 합리적인 모델링영역을 도출하고자 한다. 사용된 해석모델은 실제 상선의 이중저구조에서 사용되는 판넬에서 채택하였으며, 유한요소해석 모델링 시 3가지 서로 다른 해석영역을 제시하여 적요하였다. 본 연구의 목적은 일축압축하중이 작용하는 보강판넬구조에서 서로 다른 모델링영역을 갖는 보강판에서의 최종강도 거동을 분석하여 최적의 해석모델링 영역을 찾는 것이다.

• Earthquakes and Structures
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• 제1권1호
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• pp.69-91
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• 2010

Current seismic design codes do not contemplate explicitly some variables that are relevant for the design of structures subjected to ground motions exhibiting large energy content. Particularly, the lack of explicit consideration of the cumulative plastic demands and of the degradation of the hysteretic cycle may result in a significant underestimation of the lateral strength of reinforced concrete structures built on soft soils. This paper introduces and illustrates the use of a numerical performance-based methodology for the predesign of standard-occupation reinforced concrete ductile structures. The methodology takes into account two limit states, the performance of the non-structural system, and in the case of the life safety limit state, the effect of cumulative plastic demands and of the degradation of the hysteretic cycle on the assessment of structural performance.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2009년도 정기 학술대회
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• pp.335-338
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• 2009

일반적으로 비중이 큰 철광석이나 석탄 등을 운반하는 선박화물선의 호퍼 너클 이음부는 여러 판이 용접되어 복잡한 형상을 가지고 있어 응력이 집중되어지므로 피로강도평가 시 많은 문제점이 노출되는 구간이다. 이번 연구에서는 기존 sloping 방식의 호퍼 너클 이음 부를 갖는 180k 산적화물선 표준 모델과 제안 되어진 round 방식의 호퍼 너클 이음 부를 갖는 산적화물선에 대하여 구조강도평가와 피로강도평가를 수행하였다. 이때 합리적인 비교를 위하여 제안되어진 모델은 기존의 표준 모델의 화물창과 발라스트창의용적이 일치하도록 제안하였다. 또한 CSR을 기반으로 한 하중들에 대하여 허용응력과 25년 피로수명을 만족하도록 구조부재를 결정하였으며 피로강도평가 결과를 바탕으로 호퍼 너클부의 변화에 따른 선각 중량과 상대 건조 비 개념을 이용하여 보다 효율적인 구조를 제시 하였다.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.91-97
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• 2004

The door closer is a typical system which consists of spring and damper. The door closer is a device to close the door more slowly. The virtual prototypes of cylinder-type door closer are developed. The simulations of virtual prototype are performed to obtain the load history of the guide pin. The structural strength assessment of the guide pin is performed to verify a design safety. The fatigue life and damage of the guide pin are predicted using a FEMFAT 4.3h based on the finite element analysis.