• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.167-172
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• 1992

To analyze the effects compressive strength of concrete and longitudinal steel ratio on second-order moment of columns, 30tied rein reinforced concrete columns with hinged ends were tested. The 80mm square cross section was used and the amount of eccentricity was 24mm. The compressive strengths of column specimens with slenderness ratios of 10, 60, and 100were 250, 648 and 880kg/$\textrm{cm}^2$, and the longitudinal steel ratios were 1.98%(4-D6) and 3.95%(8-D6). The ratio of ultimate load capacity to that of short column with the same eccentricity (Pu/Pn) was much decreased at high slenderness ratio with increasing the compressive strength of concrete. And the lateral displacement of slender column at the ultimate load was decreased as the strength was increased. These are due to that at high slenderness ratio the load capacity and behavior of column are affected by flexural rigidity. And, it was also found that with increasing steel ratio, the value of Pu/Pn and the lateral displacement at the ultimate load were larger for the same slenderness ratio.

• Computers and Concrete
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• 제25권1호
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• pp.75-81
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• 2020

The purpose of this paper is to provide an experimental and analytical study on the reinforced large diameter pretensioned high strength concrete (R-LDPHC) pile. R-LDPHC pile was reinforced with infilled concrete, longitudinal, and transverse rebar to increase the flexural and shear strength of conventional large diameter PHC (LDPHC) pile without changing dimension of the pile. To evaluate the shear and flexural strength enhancement effects of R-LDPHC piles compared with conventional LDPHC pile, a two-point loading tests were conducted under simple supported conditions. Nonlinear analysis on the basis of the conventional layered sectional approach was also performed to evaluate effects of infilled concrete and longitudinal rebar on the flexural strength of conventional LDPHC pile. Moreover, ultimate strength design method was adopted to estimate the effect of transverse rebar and infilled concrete on the shear strength of a pile. The analytical results were compared with the results of the bending and shear test. Test results showed that the flexural strength and shear strength of R-LDPHC pile were increased by 2.3 times and 3.3 times compared to those of the conventional LDPHC pile, respectively. From the analytical study, it was found that the flexural strength and shear strength of R-LDPHC pile can be predicted by the analytical method by considering rebar and infilled concrete effects, and the average difference of flexural strength between experimental results and calculated result was 10.5% at the ultimate state.

• 대한금속재료학회지
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• 제50권6호
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• pp.427-432
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• 2012

This paper presents the material properties of carbon steels for ships, and offshore structures (ASTM A131) are tested under a series of arctic and cryogenic temperature conditions. For material tension tests, among the ASTM 131 steels, Grades A and B of mild steel and Grade AH of high tensile steel have been used. The obtained mechanical properties of the materials from the material tension tests were applied in a 13,000TEU class container ship to define the effect of low temperature on the ultimate longitudinal strength of the target structure by using the ALPS/HULL intelligent supersize finite element method. The tensile coupon test results showed increased strength and nonuniform fracture strain behaviors within different grades and temperatures. Increasing the material strength resulted in increasing the ultimate longitudinal strength of the ship.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.592-600
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• 2005

Ship have cutout inner bottom and girder and floor etc. Ship's structure is used much, and structure strength must be situated, but establish new concept when high stress interacts sometimes fatally the area. There is no big problem usually by aim of weight reduction, a person and change of freight, piping etc.. Because cutout's existence grow up in this place, and elastic buckling strength by load causes large effect in ultimate strength. Therefore, stiffened perforated plate considering buckling strength and ultimate strength is one of important design criteria which must examine when decide structural concept at initial design. Therefore, md, reasonable buckling strength about stiffened perforated plate need to ultimate strength limited design . Calculated ultimate strength varied several web height and cutout's dimension, and thickness in this investigated data. Used program(ANSYS) applied F.E.A code based on finite element method

• 대한조선학회논문집
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• 제28권1호
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• pp.139-149
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• 1991

본연구에서는 이상화구조요소법(理想化構造要素法)을 적용하여 선체구조(船體構造)의 최종(最終) 종강도(縱强度)를 효율적으로 해석할 수 있는 방법을 개발하였다. 이를 위해 2축방향 축력을 받는 판요소(板要素)에 대한 이상화판요소(理想化板要素)를 초기처짐과 잔류응력의 영향 및 국부구조와 전체구조간의 상관효과를 고려하여 정식화하였다. 본 해석법을 이중선각구조(二重船殼構造)로 된 4만톤급 정유운반선(精油運搬船)에 적용하여 초기처짐, 잔류응력 및 재료의 항복응력의 변화에 따른 선각(船殼)거어더의 최종(最終) 종강도(縱强度)를 해석하고, 이들 결과를 바탕으로 종강도(縱强度)측면에서의 잉여강도계수(剩餘强度係數) 및 신뢰성지표(信賴性指標)를 평가하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.230-237
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• 2000

Tubular joints of jacket structures are usually reinforced using thicker can section, internally ring stiffeners, diaphragm, or externally gusset plates to increase load carry capacity. In this paper, the effect of reinforcement type and geometric parameters of stiffener on the ultimate strength of tubular X-joints subjected to brace compression have been studied numerically Three reinforcement methods were considered; (1)can reinforcement (2)internally ring stiffener (3)internally longitudinal diaphragm. The ANSYS software was used nonlinear strength analysis. It was found that there is significant strength enhancement for reinforced joints.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 봄 학술발표회 논문집
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• pp.131-136
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• 1992

Eight singly reinforced high strength concrete beams without web reinforcement were tested to investigate their behavior and to determine their ultimate shear capacities. In this study, the main variable was the ration of longitudinal reinforcement. Test results were compared with strength predicted by using ACI code, Zsutty's dquation and Bazant & Kim's equation. As the result, for the beams of low steel ratio, the margin of safety in ACI code may be disappeared. It was shown that Zsutty.s equation well predict the trend of the test data.

• 대한조선학회논문집
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• 제32권3호
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• pp.107-115
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• 1995

본 연구에서는 선체 구조설계자가 초기설계단계에서 선각거어더의 최종 또는 잔류 종강도를 쉽게 평가할 수 있는 시스템을 SUN4 워크스테이션의 Open-Window상에 구축하였다. 즉, 현재 기본적으로 이루어지고 있는 탄성 단면계수 계산을 위한 입력정보만을 사용하여 최종 종강도 계산이 가능하도록 하기 위하여 최종종강도를 평가할 수 있는 기존의 여러 방법들을 살펴보고, 실선과 모형 Box-Girder들의 수치해석 및 실험결과들에 적용하여 비교적 유용한 방법을 선정하였다. 선정된 식 및 조사된 몇가지 식을 선각 거어더의 탄성 또는 완전소성단면계수 계산과정과 연결하여 선체가 건전한 상태(Intact Condition) 혹은 좌초나 충돌등에 의하여 손상을 받았을 때(Damaged Condition)의 최종 또는 잔류강도를 계산할 수 있게 하였다. 또한 사용자의 편리를 위하여 이 흐름을 마우스버튼을 사용하는 화면운용체계하에서 작업이 이루어지도록 구성하였으며, 3차원 그래픽환경을 구축하여 종강도 구조부재의 만성 또는 완전소성 응력상태를 제시하게 하였다. 마지막으로 개발시스템은 여러 형태의 실제 건조선박(약 20척)에 적용하여 최종 종강도평가를 수행하고 그들 분포특성 및 구조가 취약한 선박등을 파악하였으며, 설계 종굽힘모우먼트에 대해 새깅 및 호깅상태 모두 평균적으로 약 2배가 되는 최종 종굽힘모우먼트를 가지고 있음을 확인하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.97-118
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• 2019

Based on Nonlinear Finite Element Analysis (NFEA), this paper focuses on the bi-axial ultimate strength of typical bottom structures under corrosion. On one hand, uniform and not simultaneous corrosion across different structures is introduced, and surrogate models by Gaussian Process (GP) are built for both longitudinal and transverse cases individually, and corresponding probabilistic characteristics are investigated; meanwhile, corrosion effects on interaction between bi-axial stresses at ultimate state are studied. On the other hand, non-uniform localized pitting corrosion of normally distributed circular shapes is introduced, and different pitting corrosion densities are considered; structural bi-axial ultimate strengths under pitting corrosion are studied, and the results are compared with that from equivalent uniform corrosion; the probabilistic characteristics of structural ultimate strength in life cycle are studied; finally, the ultimate strength under randomly distributed pitting corrosion is compared with results from normally distributed pitting and uniform corrosion under various boundary conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.399-408
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• 2015

This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.