• Journal of Korean Society of Steel Construction
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• v.24 no.5
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• pp.521-534
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• 2012

In this research, we carry this study into effect on the basis of utilizing character of composite beam and developing applicable section to some of high strength steel. We evaluated flexural capacity of composite beam that is a unit member through experiments. The existing nominal strength formula of Composite Beam which is a previous method was reviewed and the experiment had been progressive by using each composite members as main variables though the result. Capacity evaluation of U-shape Hybrid Forming Beam(HyFo Beam) which is a new shape show as follow from the result. First, it is resonable to resist demand moment by couple moments which are occurred in concrete compressive-strength and steel tensile-strength. Second, the capacity was stably increased in proportion to the depth of beams and the thickness of steel plates. The last, HyFo Beam was showed as ductile behavior.

• Journal of Korean Society of Steel Construction
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• v.28 no.5
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• pp.355-363
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• 2016

This study numerically investigates buckling behavior of press braked steel plates with a free edge that consists of the upper flange of U-shaped box girder. Since the press-braked plates include a rounded edge, the effective width to thickness ratio of the press-braked upper flange is obscure to determine the nominal compressive strength. This study performed 3D finite element analyses to evaluate an equivalent effective width of cold-formed plate with a free edge. Through the parametric numerical analyses, the elastic buckling stresses of the rounded corner plates were compared with those of general flat plates and then, the equivalent effective width has been estimated. A comparative study with Euler buckling formula speculated in the domestic design specifications has been conducted.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.315-323
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• 2010

Five concrete compressive stress-strain models have been analyzed to check the validity of the strength method for determining the nominal moment of strengthened members using commercially available computer language. The results show that the concrete stress-strain models do not influence on the flexural analysis. The moment of a strengthened member obtained from the flexural analysis at concrete compressive strain reaching 0.003 is well agreed with nominal moment using the strength method. The flexural analysis results show that when the steel reinforcement, FRP ratio, FRP failure strain, and concrete failure compressive strain are relatively lower, the strength method overestimates the flexural capacity of the strengthened members.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.993-996
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• 2008

Compression stress block used to concrete structure design substitutes equivalent triangle, rectangle, trapezoid and parabola-rectangle stress block for actual concrete stress distribution. Its shape is different in design code of the major advanced countries. It reflects the material feature of each of country. Presently, compression stress block of korea concrete design code is equal to it of ACI code that doesn't reflect the material feature of the high strength concrete. So, many research conclusions showed that it is not reasonable. The study compares concrete stress blocks of the major advanced countries and does an experiment on concrete compression stress block to know the material feature of the concrete in korea. It obtains the operating load and the concrete strain in experiment and draw stress block parameters. It compares stress block parameters applied to design code with those by the experiment conclusion. In addition, It compares and analyses nominal axial force-moment diagram by the stress block of the major advanced countries.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.492-502
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• 2002

The dapped ends of the Gerber's beam were designed by PCI(Prestressed Concrete Institute) and CPCI(Canadian Prestressed Concrete Institute) methods. The depths of nibs with precast and topping concrete, which were halves of the total beam depth, were 77 cm md 18.2 cm, respectably. Shear tests were performed on four full scale beam ends. All specimens designed by PCI and CPCI methods showed crackings at the re-entrant coner of dap before the 32 ％ of full service design loading, and failed at the load level higher than their design strength but less than their calculated nominal strength. The specimens with increased hanger reinforcement show more effective in development of initial crackings, more ductile in failure with distributed crackings, and failed in higher strength than those of PCI requirement. The tested specimens designed by CPCI method were more ductile in failure than those of the PCI methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6A
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• pp.943-953
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• 2006

We investigated experimentally the static behavior of an orthotropic bridge deck which is made from glass fiber reinforced polymer (GFRP) and polyurethane foam. The bridge deck consists of many unit cells with rectangular holes which are filled with the foam to improve its structural behavior in its weak axis. It is found that although the elastic modulus of the foam compared to that of the GFRP is about the order of, the structural behaviors in the weak axis such as nominal strength, stiffness, etc. are greatly improved. Owing to the low mass density of the foam used in this study, the bridge deck is still light enough with the improved structural properties. Webs of the cells filled with the foam did not significantly contribute to the strength development of the deck. However, the propagation of a crack initiated in a cell is caught by the webs and limited to the inside of that cell only, which makes the load-displacement behavior of the foam-filled GFRP deck less brittle.

• Journal of Korean Society of Steel Construction
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• v.13 no.1
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• pp.19-28
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• 2001

The strength and ductility of steel flexural members are investigated experimentally in this study. As for the performance evaluation of flexural members. experimental studies on the 9 test specimens were carried out. Four specimens were fabricated from SM490 and five specimens were fabricated from SM570. The experimental results of the specimens were analyzed with focus on the flexural strength and ductility. The experimental results exhibited that all the specimens provided sufficient flexural strengthes which exceeded the nominal flexural strengthes specified in the current Limit State Design Specification by average ratio of 1.22. However. the experimental results showed that the compact-section specimens fabricated from SM570 did not provide the required rotational ductility. The yield-to-tensile strength ratio(YR) of SM570 of about 0.9 might be the causes of such insufficient capacities.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.224-227
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• 2011

케이블구조의 기하학적 비선형해석을 위한 탄성포물선 케이블요소를 제시한다. 탄성현수선 케이블요소에 대한 적합조건과 접선강도행렬을 토대로 장력이 충분히 도입되어 자중에 의한 처짐 형상이 포물선에 가깝다는 가정 하에서 무응력길이를 포함하는 탄성포물선 케이블요소의 비선형 힘-변형관계식과 접선강도 행렬을 구한다. 또한 현(chord)방향으로 두 케이블요소의 등가 공칭장력식을 정의한다. 탄성포물선 케이블 요소의 수치적인 정확성을 확인하기 위하여, 경사진 케이블을 탄성현수선과 탄성포물선 케이블요소로 각각 모델링하여 매개변수 해석을 수행하고 비교, 분석한 결과를 제시한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.454-457
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• 2011

본 논문에서는 국내에서 아직 기준이 마련되지 않은 제진설계에 대한 접근을 소개하였다. ASCE 7-05 기준에 근거하여 국내 5층 규모의 철근콘크리트 신축 건물에 제진 설계를 수행하였다. 우리나라의 현행 기준을 만족하면서 효과적인 제진 시스템 설계를 위한 방법을 소개한다. ASCE 7-05 기준에서는 제진 구조물 해석 시 부재력이 공칭강도의 1.5배를 초과하지 않은 경우 경계비선형 해석을 허용하고 있다. 이 때의 제진 설계 프로세스는 기존의 중력하중 및 등가정적하중의 75%에 의한 단면을 가정하여 부재설계를 실시하고, 선형 시간이력 해석을 통해 제진장치 및 가새를 설계한다. 이후 우리나라 실정에 맞도록 보정된 인공 지진파를 입력하여 경계비선형 해석을 실시하고, 밑면 전단력 및 층간변위 등의 만족여부를 검토한다. 이 때 목표성능을 완전탄성설계 또는 유사탄성설계로 정하여 목표성능을 만족하는지도 검토하여야 한다. 본 논문에 적용한 신축 건물은 유사탄성 설계를 위해 경계비선형 해석을 실시하였고, 가장 효과적인 제진 설계를 위해 댐퍼의 종류, 설치방법, 개수, 변위 증폭비 등을 변수로 한 case study를 진행하였다. 해석 결과 목표성능을 만족하는 범위 내에서 가장 효과적인 제진 설계는 점성댐퍼, 이층 토글형태, 증폭비 2.0, 총 8개의 댐퍼를 설치하는 것으로 나타났다.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.109-120
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• 2016

Flexural tests of full-scale concrete-filled U-shape hybrid composite beams were conducted. Ordinary (SS400) and high-strength (SM570) steel plates were used in the web and in the bottom flange of U-shape steel section respectively. The primary objectives were to develop the hybrid section configuration with maximized flexural capacity and to investigate its flexural strength and deformation capacity. All the hybrid test specimens in this study exhibited the plastic moment capacity and resonable deformability. It is shown that the plastic stress distribution can be assumed in calculating the flexural strength of the proposed hybrid composite beams if the plastic neural axis is located within 15% of the total beam depth from the top of the composite slab. The procedure for computing the effective flexural stiffness of hybrid composite beams is also recommended based on test results.