• 산업기술연구
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• 제17권
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• pp.291-295
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• 1997

The tests of stress corrosion cracking in structural carbon steel were carried out under the conditions of acid fog and general water. As the result of measurement SCC rupture time under acid fog was observed to be much shorter than that of general water at the same stress level. Therefore, acid fog drops the SCC strength in structural carbon steel due to strong corrosion. In the SCC process by acid fog, crack initiation was caused by pit corrosion and local stress concentration, and distinctive feature of crack growth shows branching since crack grows to the corrosion direction. Moreover, corrosion products were observed by clevage corrosion on the crack surfaces.

• International Journal of Concrete Structures and Materials
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• 제10권4호
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• pp.435-450
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• 2016

Experimental studies were conducted on 36 grouted splices to investigate their mechanical performance under four loading schemes: (1) incremental tensile loading, (2) repeated tensile loading, (3) cyclic loading at high stress, and (4) cyclic loading at large strain. Load-deformation responses of the grouted splices under cyclic loadings were featured with pinching effect and stiffness degradation compared to those responses under tensile loadings. The shape of the hysteresis loops of load-deformation curves was similar to that under incremental tensile loading. For the purpose of structural analysis, stress-strain relationships were presented for grouted splices under various loadings.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.445-450
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• 2006

It is proposed that the electromechanical relation of the conductive materials with high electrical resistance may be used to estimate the current stress of prestressing tendons. To choose the best conductive material to this end, we studied the electromechanical relations of carbon fibers and metalic heat wires experimentally. It is found that the relation of carbon fibers can be modelled by a parabolic(or hyperbolic) function in the early stage of deformation. However because the relation is not consistent when it is unloaded and reload, carbon fibers are not suitable for this purpose. Metallic heat wires show a consistent linear relation during loading and unloading in the elastic deformation and are suitable for this purpose. To estimate the electromechanics relation of metallic wires, we developed a simple formula based on the rigid plasticity. We propose a new kind of prestressing tendons whose stress can be monitored.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.79-86
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• 2015

The purpose of this study is to evaluate structural integrity of a weldment which is partially screwed and then welded. Two finite element models are constructed and solved: operating temperature and internal pressure are considered in the first simple model, and welding process and normal operating condition including heat-up process are simulated in the second model. Structural integrity assessment criteria are satisfied with both finite element models, therefore the repair weldment finely sustains structural integrity of this assembly and prevents leakage. Stresses are dramatically increased when weld residual stress is considered, but it should be considered as a secondary stress.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.207-211
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• 2015

In this paper, 2 kinds of models about bike frame are simulated with static structural analysis. A bike frame with diamond type is compared with another model that Down tube is eliminated from original diamond frame. About both types of models, Property of a material and conditions of restriction & load are the same. This study shows reinforcement effects of a partial frame by adding down tube and impacts generated by applying a load at the frame such as weak points & high stress parts as well as expected deformation. The structural result of this study indicates that the equivalent stress or total deformation decreases by 57.1% or 36.4%, respectively. Also stress concentration sites are leg connecting parts, front/rear wheels fixed region and Max deformation is generated from Seat tube. In conclusion, A Down tube is highly efficient as reinforcement than frame without non down tube. Furthermore, The safety rises in case of reducing top tube thickness and increasing a reinforcement at leg connecting parts or concentration regions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.354-361
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• 2002

This paper propose section properties factor to generate stress history for fatigue analysis and safety inspection of steel bridge. A methodology is described for the computation of numerical stress histories in the steel truss bridge, caused by the vehicles using section properties factor. The global 3-D beam model of bridge is combined with the local shell model of selected details. Joint geometry is introduced by the local shell model. The global beam model takes the effects of joint rigidity and interaction of structural elements into account. Connection nodes in the global beam model correspond to the end cross-section centroids of the local shell model. Their displacements are interpreted as imposed deformations on the local shell model. The load cases fur the global model simulate the vertical unit force along the stringers. The load cases fer the local model are imposed unit deformations. Combining these, and applying vehicle loads, numerical stress histories are obtained. The method is illustrated by test load results of an existing bridge.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.839-844
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• 2007

In order to reduce resultant stress of the connection detail of longitudinal and rib and floor beam, in this study, the parameter studies for the reinforcement details as the bulk head and the vertical rib were preformed with FE analysis. As the result, it was shown that reinforcement detail with the bulk head plate in longitudinal rig reduced generally the principal stress at the connection detail, but the stress concentration of the weld toe parts occurring fatigue crack increased. However, it was known that the reinforcement detail with the vertical rib in the rib is more effective than the bulk head plate of the reduction stress concentration in the weld toe parts.

• 한국농촌건축학회논문집
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• 제18권2호
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• pp.11-18
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• 2016

The collapsing accidents of greenhouse frames have been increased yearly due to strong wind and heavy snow, but as it was, there were few studies about the structural safety of greenhouses. Therefore, this study was carried out to develop the stress tolerant structural frame systems in built-up greenhouses. The vertical loading experiment of developed scale models were implemented and the developed types of models were simulated by 3-D analysis program in this study. These types of models, which are existing type and honeycomb type, in arch and standard style frames were classified. As a result of this study, it was verified that the honeycomb type model of arch style frame is better than the existing type model of it in stress resistance against snow load and wind load.

• Structural Engineering and Mechanics
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• 제8권1호
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• pp.103-118
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• 1999

The structural integrity of the reactor pressure vessel under pressurized thermal shock (PTS) is evaluated in this study. For given material properties and transient histories such as temperature and pressure, the stress distribution is found and stress intensity factors are obtained for a wide range of crack sizes. The stress intensity factors are compared with the fracture toughness to check if cracking is expected to occur during the transient. A round robin problem of the PTS during a small break loss of coolant transient has been analyzed as a part of the international comparative assessment study, and the evaluation results are discussed. The maximum allowable nil-ductility transition temperatures are determined for various crack sizes.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.203-204
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• 2017

In case of developing a guide-rail type window cleaning robot, only the first prototype has been developed. In this study, it was considered that the size and the load of the window cleaning robot was not optimized, and through the structural analysis of the self-weight of the window cleaning robot, the stress concentration area was derived and the concentrated stress was quantified. Analysis showed that the upper rail shaft had a bending stress of 9.964Mpa and the bolt had a shear stress of 19.544Mpa. The results of this study will be used as basic data for designing future prototypes.