• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.763-770
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• 1998

This paper deals with evaluation of bending fatigue strength in SCM415 carburized spur gears. The constant stress amplitude fatigue test is performed by using an electrohydraulic servo-controlled pulsating tester. The S-N curves are obtained and the enhanvement of fatigue strength due to carburized treatment is clarified. In this study the improvement of fatigue strength is assumed to be caused by an increase of both hardness and residual stress and experimental formula has been proposed for the estimation of bending fatigue strength of carburized gears. The effect of surface conditions on the fatigue strength is evaluated quantitatively and it is close to the relative surface condition factor used in the ISO strength rating formula.

• Structural Engineering and Mechanics
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• 제19권6호
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• pp.653-677
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• 2005

Concrete filled steel tubular columns (CFT) are widely used in civil engineering works, especially in large scale of works because of high strength, deformation, toughness and so on. On the other hand, as a kind of strengthening measure for seriously damaged reinforced concrete piers of viaduct in Hansin-Awaji earthquake of Japan in 1995, reinforced concrete piers were wrapped with steel plate. Then, a new kind of structure appeared, that is, reinforced concrete filled steel tubular column (RCFT). In this paper, compression test and bending-shearing test on RCFT are carried out. The main parameters of experiments are (1) strength of concrete, (2) steel tube with or without rib, (3) width-thickness ratio and (4) arrangement of reinforcing bars. According to the experimental results, the effect of parameters on mechanical characteristics of RCFT is analyzed clearly. At the same time, strength evaluation formula for RCFT column is proposed and tested by experimental results and existed recommendations (AIJ 1997). The strength calculated by the proposal formula is in good agreement with test result. As a result, the proposed evaluation formula can evaluate the strength of RCFT column properly.

• 한국안전학회지
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• 제32권5호
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• pp.69-75
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• 2017

Structural safety evaluation for static strength of thin plate RC member with high strength concrete is conducted in this study. Static strengths were predicted and compared with the experimental values. Predicted values were calculated by the evaluation formula based on the punching shear behavior and the yield line theory which can appear in the plate members. Static load tests were carried out for the specimens with high strength concrete and the test results were compared with the required performance in design. The comparison results show that the specimens with high strength concrete have sufficient structural safety for flexural and punching shear performance required in design. High strength concrete specimens exhibited excellent strength despite their small thickness. The range of concrete strengths applied in this study was about 60 MPa to 100 MPa.

• 한국강구조학회 논문집
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• 제13권6호
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• pp.641-649
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• 2001

본 논문에서는 데크플레이트의 웨브 국부좌굴에 관한 실용적인 내력식을 제안하고자 한다. 실험에서 유추된 해석모델을 이론적으로 규명한 기존의 연구를 바탕으로 내력에 영향을 미치는 주요 변수들을 조사 분석하여 관련 함수들을 유도한다. 각 변수들을 기존의 실험자료와 종합적으로 비교 분석하여 간편한 내력식을 제안한다. 유럽기준 EC 3 부록 Z 에 따른 통계평가로부터 저항 부분안전계수 ${\gamma}_M$ 을 구하며 목표로 하는 값 1.1과 비교되어진다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.526-529
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• 2006

In this paper, flexure behavior of steel fiber reinforcement ultra high performance cementations composites (SFR-UHPCC) has been analyzed by equivalent stress block. Pulling-out tensile force of steel fiber with concrete matrix was induced. An appropriate flexure evaluation formula, i.e. semi-analytical formula, was established based on rectangular cross section beam for comparing with shear capacity and ultimate load of SFR-UHPCC beam. Finally, the semi-analytical formula has been simplified for the convenience of design work. Experimental results and theoretical shear strength are shown to compare with the formula proposed by this paper. The theory formula has a good prediction of failure type of SFR-UHPCC.

• Structural Engineering and Mechanics
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• 제58권1호
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• pp.1-19
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• 2016

Recently, the high-strength concrete is increasingly used in the construction of reinforced concrete structures due to its benefits, but this use is influenced negatively on the local ductility of structural elements. The objective of this study is the prediction of a new approach to evaluate the curvature ductility factor of high strength concrete beams according to Eurocode 2. After the presentation of the Constitutive laws of materials and the evaluation method of curvature ductility according to the Eurocode 2, we conduct a parametric study on the factors influencing the curvature ductility of inflected sections. The calibrating of the obtained results allows predicting a very simple approach for estimating the curvature ductility factor. The proposed formula allows to calculate the curvature ductility factor of high strength concrete beams directly according to the concrete strength $f_{ck}$, the yield strength of steel $f_{yk}$ and the ratio of tension and compression reinforcements ${\rho}$ and ${\rho}^{\prime}$ respectively, this proposed formula is validated by theoretical and experimental results of different researchers.

• 한국건설순환자원학회논문집
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• 제5권3호
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• pp.261-266
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• 2017

본 연구에서는 플라이애시 첨가량과 콘크리트 압축강도를 실험변수로 설정하여 하이볼륨 플라이애시 시멘트를 사용한 무근 콘크리트의 2면전단거동에 관한 실험을 수행한 후, 하이볼륨 플라이애시 시멘트 콘크리트의 전단특성을 파악하고자 하였다. 실험 결과, 전단 강도의 변화는 일반적으로 알려진 것과 유사하게 압축 강도의 증가에 따라 증가하는 경향이 나타났다. 콘크리트 구조설계기준(KCI, 2007)에서 제안한 콘크리트 전단강도 식은 실험결과와 유사한 경향을 보이고 있어 다량 치환된 플라이애시 시멘트 콘크리트의 전단강도는 콘크리트 구조설계기준에서 제시하고 있는 식을 준용하여도 큰 문제는 없을 것으로 예상된다. 한편 플라이애시 첨가율에 따른 다량 치환된 플라이애시 시멘트 콘크리트의 전단강도는 플라이애시 첨가율을 고려한 경우가 첨가율을 고려하지 않은 경우보다 훨씬 더 높은 상관성을 가지는 것으로 나타나, 비록 플라이애시 첨가율을 고려하지 않아도 현행 설계기준 식에 적절하기는 하지만 좀 더 상관성이 높은 식을 제안하였다.

• Steel and Composite Structures
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• 제3권2호
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• pp.123-140
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• 2003

The importance of the research on moment-resistant properties of unstiffened tubular joints and the research background are introduced. The performed experimental research on the bending rigidity and capacity of the joints is reported. The emphasis is put on the discussion of the flexural behavior of the joints including sets of geometrical parameters of the joints and several loading combinations. Procedures and results of loading tests on four full size joints in planar KK and X configuration are described in details at first. Mechanical models are proposed to analyze the joint specimens. Three-dimensional nonlinear FE models are established and verified with the experimental results. By comparing the experimental data with the results of the analysis, it is reported reasonable to carry out the structural analysis under the assumption that the joint is fully rigidly connected, and their bending capacities can assure the strength of the members connected under certain limitation. Furthermore, a parametric formula for inplane bengding rigidity of T and Y type tubular joints is proposed on the basis of FE calculation and regression analysis. Compared with test results, it is shown that the parametric formula developed in this paper has good applicability.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권1호
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• pp.101-115
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• 2013

This paper examines the application of structural reliability analysis to submarine pressure hulls to clarify the merits of probabilistic approach in respect thereof. Ultimate strength prediction methods which take the inelastic behavior of ring-stiffened cylindrical shells and hemi-spherical shells into account are reviewed. The modeling uncertainties in terms of bias and coefficient of variation for failure prediction methods in current design guidelines are defined by evaluating the compiled experimental data. A simple ultimate strength formulation for ring-stiffened cylinders taking into account the interaction between local and global failure modes and an ultimate strength formula for hemispherical shells which have better accuracy and reliability than current design codes are taken as basis for reliability analysis. The effects of randomness of geometrical and material properties on failure are assessed by a prelimnary study on reference models. By evaluation of sensitivity factors important variables are determined and comparesons are made with conclusions of previous reliability studies.

• 대한토목학회논문집
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• 제41권2호
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• pp.101-111
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• 2021

전단마찰 시험체는 재하형태에 따라 압축재하와 인장재하 시험으로 구분된다. 인장재하 시험의 경우에는 외력으로 작용하는 수직방향 인장력에 의하여 전단응력 및 수직방향 인장응력이 유발된다. 이 연구에서는 압축장 이론을 이용하여 인장재하 시험체의 전단전달강도를 평가하였으며, 2축-응력 상태의 콘크리트 최대 압축강도의 변화를 고려하기 위하여 수정압축장이론, 연화트러스모델의 구성방정식을 사용하였다. 타당성 검증을 위하여 과거 연구자들에 의해 수행된 직접전단강도 실험값들과 압축장 이론을 이용하여 구한 값들을 비교한 결과, 비균열 인장재하 시험체의 경우 예측값과 실측치가 대체적으로 잘 일치함을 확인하였다. 또한 콘크리트 스트럿의 유효압축강도를 고려한 전단강도 평가식을 제안하고, 기존 문헌에 수록된 실험결과와 비교함으로써 제안식의 적용 가능성을 검증하였다.