• 대한조선학회논문집
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• 제60권1호
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• pp.20-30
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• 2023

In this paper, the Energy Flow Finite Element Analysis (EFFEA) was performed to predict the acoustic and vibrational responses of complicated plate structures considering improved Fluid-Structure Interaction (FSI). For this, a new power transfer relationship was derived at the area junction where two different fluids are in contact on both sides of the plate. In order to increase the reliability of EFFEA of complicated plate structures immersed in a high-density fluid, the corrected flexural wavenumber and group velocity considering fluid-loading effect were derived. As the specific acoustic impedance of the fluid in contact with the plate increases, the flexural wavenumber of the plate increases. As a result, the flexural group velocity is reduced, and the spatial damping effect of the flexural energy density is increased. Additionally, for the EFFEA of arbitary-shaped built-up structures, the energy flow finite element formulation for the acoustic tetrahedral element was newly performed. Finally, for validation of the derived theory and developed software, numerical applications of complicated plate structures submerged in seawater or air were successfully performed.

• 콘크리트학회논문집
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• 제20권6호
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• pp.809-820
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• 2008

니브 플레이트 길이가 1,500 mm인 새로운 실물크기 개량 더블티 슬래브를 제안, 설계하고 종국 휨강도까지 실험에 의하여 평가하였다. 이 슬래브는 기존의 PCI 더블티와 같은 티 (tee)단면과 새로이 개조된 플레이트단면으로 구성되어있으며, 긴장력은 티 (tee)단면 하부에만 적용되었다. 이 실험체는 국내 프리캐스트 공장에서 제작한 실험체이다. 휨실험에 의하여 티 (tee)단면이 종국 휨강도를 발휘할 때까지 개조된 댑단부를 포함한 니브 플레이트 단면의 안전성과 사용성을 평가하려 하였다. 하중을 가력할수록 초기 휨 균열들이 더블티 하단에서 발생하였고, 그 후 휨전단과 사인장 균열들은 댑단부와 니브 부분으로 증가하여 발생하였다. 제안한 개량 더블티 슬래브는 설계하중 이상의 휨 내력으로 고르게 분포된 많은 휨균열과 함께 연성 파괴되었다. 두께 250 mm의 니브 플레이트부분은 사용하중 하에서 어떠한 균열도 발생하지 않았고, 티 (tee)부분의 극한하중 하에서도 미소한 휨균열만 보여주었다. 제안하는 실험체는 이 실험에서 설계기준 조건을 만족시키는 강도와 연성거동을 보여주었다. 보다 효율적인 활용을 위하여, 니브 플레이트 두께와 인장철근을 감소시킬 수 있는 추가 실험이 제안하는 개량 댑 더블티에 대하여 요구된다.

• 대한토목학회논문집
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• 제5권4호
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• pp.113-119
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• 1985

본(本) 논문(論文)에서는 휨하중을 받는 콘크리트의 피로특성 및 피로신뢰성이 연구(硏究)되었다. 콘크리트보에 대한 피로실험이 수행되었으며, 피로하중은 4 점하중 상태로 작용되었다. 본(本) 실험결과(實驗結果)로부터 S-N 관계가 얻어졌으며, 콘크리트의 휨피로 강도를 예측하기 위한 공식(公式)이 도출되었다. 또한 본(本) 논문(論文)에서는 콘크리트의 휨피로에 대한 확률론적 해석방법이 제안되었다. 본(本) 연구결과(硏究結果) 콘크리트의 피로거동을 서술하는 데는 Weibull 분포가 적절한 것으로 나타났다.

• 콘크리트학회논문집
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• 제12권2호
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• pp.71-78
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• 2000

This paper presents a study on the flexural rigidity of reinforced high strength concrete beams. Thirty six beams with different compressive strength of concrete, tensile reinforcement ratio, compressive reinforcement ratio, and pattern of loadings(1 point loading and 2 points loading) were tested to evaluate the effective moment of inertia. According to the experimental results, the eqation(1) proposed by ACI code for the effective moment of inertia overestimated that of simply supported reinforced high strength concrete beams. Thus, in this paper, an empirical equation(3) is proposed as a lower bound of 90% confidence limit to estimate the effective moment of inertia of simply supported reinforced high strength concrete beams.

• Steel and Composite Structures
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• 제9권1호
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• pp.19-38
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• 2009

The present paper provides test data to evaluate the seismic performance of recycled aggregate concrete (RAC) filled steel square hollow section (SHS) beam-columns. Fifteen specimens, including 12 RAC filled steel tubular (RACFST) columns and 3 reference conventional concrete filled steel tubular (CFST) columns, were tested under reversed cyclic flexural loading while subjected to constant axially compressive load. The test parameters include: (1) axial load level (n), from 0.05 to 0.47; and (2) recycled coarse aggregate replacement ratio (r), from 0 to 50%. It was found that, generally, the seismic performance of RACFST columns was similar to that of the reference conventional CFST columns, and RACFST columns exhibited high levels of bearing capacity and ductility. Comparisons are made with predicted RACFST beam-column bearing capacities and flexural stiffness using current design codes. A theoretical model for conventional CFST beam-columns is employed in this paper for square RACFST beam-columns. The predicted load versus deformation hysteretic curves are found to exhibit satisfactory agreement with test results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.166-169
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• 2006

A new bridge system described in this paper uses concrete-filled steel tube (CFT) girders as a replacement for conventional girders. Experimental investigations were carried out to comprehend the flexural behavior of CFT girder-slab deck composite section. The experimental investigation consisted of designing and constructing a test specimen and loading it to collapse in bending to check the applicability of the system. The test results showed that concrete filled steel tube girders have good ductility and maintain its strength up to the end of the loading. In the test, the flexural behavior of each specimen of CFT girder-deck composite section is identified.

• Steel and Composite Structures
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• 제21권4호
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• pp.775-789
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• 2016

This paper presents the flexural behavior & ultimate strength performance of innovative light weight sandwich panels of size $3{\times}1.2m$ with two different solidity ratios viz. 0.5 and 0.33 under out of plane bending load. From the experimental studies, it is observed that the flexural strength and the stiffness are increased by about 46% and five folds for lesser solidity ratio case. From the measured strains of the shear connectors, full shear transfer between the concrete wythes is observed. The yielding occurred approximately at 4% and 0.55% of the ultimate deformation for 100 mm & 150 mm thick panels, which shows the large ductility characteristics of the panels. From the study, it is inferred that the light weight sandwich panels behave structurally in a very similar manner to reinforced concrete panels. Further from the numerical study, it is observed that the numerical values obtained by FE analysis are in good agreement with the experimental observations.

• 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.

• Structural Engineering and Mechanics
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• 제52권3호
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• pp.559-572
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• 2014

This paper presents the results of an experimental investigation on the flexural behavior of doubly reinforced lightweight concrete (R.L.C.) beams tested under cyclic loading. A total of 20 beam specimens were tested. Test results are presented in terms of ductility index, the degradation of strength and stiffness, and energy dissipation. The flexural properties of R.L.C. beam were compared to those of normal concrete (R.C.) beams. Test results show that R.L.C. beam with low and medium concrete strength (20, 40MPa) performed displacement ductility similar to the R.C. beam. The ductility can be improved by enhancing the concrete strength or decreasing the tension reinforcement ratio. Using lightweight aggregate in concrete is advantageous to the dynamic stiffness of R.L.C. beam. Enhancement of concrete strength and increase of reinforcement ratio will lead to increase of the stiffness degradation of beam. The energy dissipation of R.L.C beam, similar to R.C. beam, increase with the increase of tension reinforcement ratio. The energy dissipation of unit load cycle for smaller tension reinforcement ratio is relatively less than that of beam with higher reinforcement ratio.

• 콘크리트학회지
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• 제3권3호
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• pp.149-157
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• 1991

본 논문은 반복하중을 받는 철근콘크리트 휨부재를 비선형해석하기 위한 것으로서, 재료의 구성방정식도출, 비선형 프로그램의 개발 및 개발된 프로그램의 검증으로 구성되어 있다. 재료의 구성방정식도출에서 콘크리트는 직교이방성재료로 모형화하고, 철근은 탄소성모형으로 취하였다. 반복하중하에서 휨부재의 압축부 콘크리트에 이력거동과 강성감소, 인장부 콘크리트에는 균열개폐거동과 균열변형률의 개념을 도입하여 콘크리트의 구성방정식을 도출하였다. 반북하중을 받는 철근콘크리트 휨부재를 해석하기 위하여 4절점등매개요소와 트러스요소의 유한요소정식과 증분반복기법을 적용한 유한요소프로그램을 도출하고, 반복하중을 받는 과소 철근콘크리트 보에 대한 실험결과와 해석결과를 비교하여 개발된 재료모형과 해석프로그램의 타당성을 검증하였다.