• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.79-81
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• 2005

Bridges constructed recently are preferred to have long spans and simple structure details considering not only the function as bridge but scenic beauty, maintenance, construction term and life cycle cost, etc. Therefore, they require high performance steels like extra-thick plate steels and TMCP steels. A TMCP steel produced by themo-mechanical control process is now spot lighted due to the weldability for less carbon equivalent. It improved at strength and toughness in microstructure. Recently, the SM570-TMC steel which is a high strength TMCP steel whose tensile strength is 600MPa has been developed and applied to steel structures. But, for the application of this steel to steel structures, it is necessary to elucidate not only the material characteristics but also the mechanical characteristic of welded joints. In this study, the characteristics of residual stresses in welded joints of SM570-TMC steel were studied through the three-dimensional thermal elastic-plastic analyses on the basis of mechanical properties at high temperatures obtained from the elevated temperature tensile test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.1125-1132
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• 2009

The theory and a probe of the pilot hole wall deformation method, which is a 3-dimensional stress measurement method based on the stress relief principle, were developed. A pilot hole is drilled from the bottom of a borehole and the stress measurement probe is inserted into the pilot hole. The borehole is advanced as the overcoring and the changes in the radius of the pilot hole in three directions and in the axial lengths between the borehole bottom and the pilot hole wall along four axial lines are measured by cantilever type-displacement sensors. The differences between the displacements by the elastic stress analysis and those measured by using the probe were within 3% in the uniaxial compression test of an acrylic resin plate having a hole.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.425-431
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• 2001

In order to take account of the statistical properties of probability variables used in the structural analysis, the conventional approach using the safety factor based on past experience usually estimated the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, material characters and the dimensions of the members. But the errors should be considered systematically in the structural analysis. Structural safety could not precisely be appraised by the traditional structural design concept. Recently, new approach based on the probability concept has been applied to the assessment of structural safety using the reliability concept. In this study, safety of structures will estimated by the reliability analysis with commercial structural software that has the tools of nonlinear elastic-plastic 3-D analysis. Experimental test result is compared to results from this research and Coan/sup 1)/ In this paper, AFOSM(Advanced First-Order Second Moment method) is applied with von Mises, Tresca and Mohr-Coulomb failure criterions. The reliability index β and probability of failure P/sub f/ can be obtained by following this practical procedure as judgement a safety of structures and necessity of reinforcing.

• 대한조선학회지
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• 제17권4호
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• pp.1-11
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• 1980

Stiffened plates are commonly used as a component of ship's structures. Most frequently symmetrically stiffened plates are used, but some of stern structures and any specified parts are often constructed with eccentrically stiffened plates. The problems of these eccentrically stiffened plates have been studied rarely, and the results of eccentricity effect of eccentrically stiffened plates are not available. This paper deals with the analysis of eccentrically stiffened plates in the linear elastic range. The derivation of the stiffness matrix was carried out by finite element method for which the isoparametric element was adopted. To show the effect of eccentricity, the deflection at the center under the uniformly distributed and the concentrated load of simply supported and clamped plate models are computed respectively in accordance with the eccentricity of the stiffener. As shown in the results of computations, the eccentricity effect of concentrated load case is greater than that of distributed load case and that of simply supported boundary condition is greater than that of clamped boundary condition. The higher eccentricity of stiffener is, the smaller the effect of stiffener becomes, therefore scantling of eccentrically stiffened plates should be considerably greater than those of symmetrically stiffened plates.

• 대한조선학회지
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• 제20권1호
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• pp.11-20
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• 1983

In this paper elastic-plastic large deflection analysis of ship structural members, plates, stiffened plates and cylindrical shallow shell, are performed by the finite element method. And for the consideration of the yielded propagation through the depth of the member, the layered element approach is employed. The present method is justified by comparing its results with those of experiment and others. As results, the nonlinear behavior and the ultimate strength curves are shown, which can be used in the design of the plates and the stiffened plates under compression, and the applicability to the shell structures is suggested. The analysis results are as followings. (1) The results of the approximate equations as well as those of buckling analysis may not guarantee precisely the safety of the structures in some cases and the optimum in other cases. Therefore they may not show the design criteria for the optimal design. (2) As the initial deflection increases, its effects on the ultimate strength of the structure generally increases, and the ultimate load, therefore, decreases. (3) This approach can be applied to the shell type structures. (4) The present method can be applied to the various structures composed of plate and beam members, for example, plates with hole and the stiffened plates with hole stiffened by spigot, doubler and/or stiffener, for the optimal design.

• 전산구조공학
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• 제4권1호
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• pp.73-82
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• 1991

판의 탄소성 좌굴문제는 판 구조의 해석과 설계시의 중요성으로 인하여 상당한 관심이 모아져 온 분야이다. 본 연구에서는 유한요소법에 의한 효율적인 탄소성 좌굴해석 프로그램을 개발하였다. 탄소성 강성행렬을 구성하기 위한 소성이론으로는 실험결과와 잘 일치하는 Stowell의 변형이론을 사용하였으며, 좌굴하중을 해석하기 위해서는 고유치해석에 의한 반복기법을 사용하였다. 고유치해석에서는 불필요한 고유치의 계산을 피할 수 있는 subspace반복기법을 사용하였다. 해석결과를 Stowell이 제시한 이론해와 Pride에 의한 실험결과와 비교하여 프로그램의 타당성을 보이고, 이를 이용하여 단순지지, 또는 고정된 경계조건에 대하여 일축 또는 이축응력이 작용되는 여러 경우에 대하여 좌굴하중을 구하였다. 또한, 탄소성 좌굴에 미치는 형상비의 영향을 검토하였다.

• Coupled systems mechanics
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• 제1권1호
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• pp.1-7
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• 2012

The problem of laterally loaded piles is particularly a complex soil-structure interaction problem. The flexural stresses developed due to the combined action of axial load and bending moment must be evaluated in a realistic and rational manner for safe and economical design of pile foundation. The paper reports the finite element analysis of pile groups. For this purpose simplified models along the lines similar to that suggested by Desai et al. (1981) are used for idealizing various elements of the foundation system. The pile is idealized one dimensional beam element, pile cap as two dimensional plate element and the soil as independent closely spaced linearly elastic springs. The analysis takes into consideration the effect of interaction between pile cap and soil underlying it. The pile group is considered to have been embedded in cohesive soil. The parametric study is carried out to examine the effect of pile spacing, pile diameter, number of piles and arrangement of pile on the responses of pile group. The responses considered include the displacement at top of pile group and bending moment in piles. The results obtained using the simplified approach of the F.E. analysis are further compared with the results of the complete 3-D F.E. analysis published earlier and fair agreement is observed in the either result.

• Structural Engineering and Mechanics
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• 제28권3호
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• pp.281-294
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• 2008

In this paper, linear elastic isotropic structures under the effects of both stochastic operators and stochastic excitations are studied. The analysis utilizes the spectral stochastic finite elements (SSFEM) with its two main expansions namely; Neumann and Homogeneous Chaos expansions. The random excitation and the random operator fields are assumed to be second order stochastic processes. The formulations are obtained for the system solution of the two dimensional problems of plane strain and plate bending structures under stochastic loading and relevant rigidity using the previously mentioned expansions. Two finite element programs were developed to incorporate such formulations. Two illustrative examples are introduced: the first is a reinforced concrete culvert with stochastic rigidity subjected to a stochastic load where the culvert is modeled as plane strain problem. The second example is a simply supported square reinforced concrete slab subjected to out of plane loading in which the slab flexural rigidity and the applied load are considered stochastic. In each of the two examples, the first two statistical moments of displacement are evaluated using both expansions. The probability density function of the structure response of each problem is obtained using Homogeneous Chaos expansion.

• Structural Engineering and Mechanics
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• 제74권1호
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• pp.19-32
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• 2020

Metallic energy-dissipation dampers are widely used in structures. They are comprised of an added damping and stiffness (ADAS) device with many parallel, diamond-shaped hole plates, the neck width of which is an important parameter. However, no studies have analyzed the neck width's influence on the ADAS device's performance. This study aims to better understand that influence by conducting a pseudo-static test on ADAS, with three different neck widths, and performing finite element analysis (FEA) models. Based on the FEA results and mechanical theory, a design neck width range was proposed. The results showed that when the neck width was within the specified range, the diamond-shaped hole plate achieved an ideal yield state with minimal stress concentration, where the ADAS had an optimal energy dissipation performance and the brittle shear fracture on the neck was avoided. The theoretical values of the ADAS yield loads were in good agreement with the test values. While the theoretical value of the elastic stiffness was lower than the test value, the discrepancy could be reduced with the proposed modified coefficient.

• 소성∙가공
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• 제23권3호
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• pp.171-177
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• 2014

The current collector for the molten carbonate fuel cell (MCFC) which has sheared protrusions is manufactured by the three-stage forming process that integrates slitting, preforming and final forming. Due to the repetition of sheared protrusions, an effective simulation method is required to predict the mechanical behavior. In the current study, a sheet with sheared protrusions was assumed to be an orthotropic plate, which has the same length, width and height. FEM simulations were conducted to evaluate the homogenized properties of the current collector, which has 4 (longitudinal direction) x 4 (transverse direction) sheared protrusions. The simulation model was constructed using hexahedral mesh coarsening. From the verification examples, it was found that the proposed simulation method was efficient within reasonable accuracy. The calculated homogenized properties can be applied to the design of a stack for molten carbonate fuel cells and the prediction of mechanical behavior for other applications.