• Computers and Concrete
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• 제17권3호
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• pp.337-351
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• 2016

This paper presents the properties of pervious concrete containing high-calcium fly ash. The water to binder ratios of 0.19, 0.22, and 0.25, designed void ratios of 15, 20, and 25%, and fly ash replacements of 10, 20, and 30% were used. The results showed that the use of fly ash as partial replacement of Portland cement enhanced the mixing of paste resulting in a uniform mix and reduced amount of superplasticizer used in the mixture. The compressive strength and flexural strength of pervious concrete were slightly reduced with an increase in fly ash replacement level, while the abrasion resistance increased due mainly to the pozzolanic and filler effects. The compressive strength and flexural strengths at 28 days were still higher than 85% of the control concrete. The aggregate size also had a significant effect on the strength of pervious concrete. The compressive strength and flexural strength of pervious concrete with large aggregate were higher than that with small aggregate.

• 한국강구조학회 논문집
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• 제10권4호통권37호
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• pp.677-689
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• 1998

본 연구에서는 중심압축력을 받는 스털스터드의 설계강도에 대하여 다루었으며 비교 평가하였다. 미국규준인 냉간성형 LRFD 설계규준 (AISI). 유럽의 냉간박벽부재설계규준 (EC3 part 1.3) 및 독일의 관련규정 (DASt-Richtlinie 016)의 유사성과 차이점을 소개하고 분석하며 체계적으로 평가하였다. 특히 유효폭과 전체 안정성문제 (휨좌굴과 비틀림좌굴)가 이 논문에서 내포되어 있다. 또한 예제를 통하여 두 규준인 AISI와 EC3에 의한 설계압축강도를 산정하고 비교 분석하였다.

• 한국전산구조공학회논문집
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• 제18권4호통권70호
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• pp.417-426
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• 2005

최근 경량, 고강도, 내부식, 고내구성 특성 등의 여러 가지 이점이 있는 복합소재 교량 바닥판에 대한 관심이 고조되고 있다. 본 연구에서는 유리섬유와 불포화 폴리에스터를 사용하여 진공성형제조기법으로 파형코어 복합소재 모델 바닥판을 제작하였다. 모델 바닥판은 제형, 박스형, 삼각형 단면을 고려하였고, 각각 강축과 약축에 대한 시험 모델에 대하여 3점 휨 시험을 실시하였다. 시험 결과로부터 얻은 하중-변위곡선, 하중-변형률 곡선, 파괴모드 등을 분석하여 복합소재 바닥판의 휨 거동특성을 파악하고자 하였으며, 파형코어 복합소재 바닥판을 교량 바닥판으로 적용할 수 있는 가능성을 검토하였다. 또한 등가 중량으로 환산한 강축과 약축 모델에 대해 휨 거동 특성을 비교하여 가장 효과적이고 경제적인 단면을 찾고자 하였다.

• Structural Engineering and Mechanics
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• 제75권5호
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• pp.595-605
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• 2020

In this study, the flexural behaviors of full-scale prestressed concrete box girders are experimentally investigated. Four girders were fabricated using two types of concrete (compressive strengths: 50 MPa and 70 MPa) and tested under four-point bending until failure. The measured parameters included the deflection, the stress and strain in concrete and steel bars, and cracks in concrete. The measurement results were used to analyze the failure mode, load-bearing capacity, and deformability of each girder. A finite element model is established to simulate the flexural behaviors of the girders. The results show that the use of high-performance concrete and reasonable combination of prestressed tendons could improve the mechanical performance of the box girders, in terms of the crack resistance, load-carrying capacity, stress distribution, and ductility.

• Computers and Concrete
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• 제26권1호
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• pp.95-106
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• 2020

Castellated beams fabricated from standard I-sections are being used for several structural applications such as commercial and industrial buildings, multistory buildings, warehouses and portal frames in view of numerous advantages. The advantages include enhanced moment of inertia, stiffness, flexural resistance, reduction in weight of structure, by passing the used plate girders, the passage of service through the web openings etc. In the present study, experimental and numerical investigations were carried out on concrete encased steel castellated beams with hexagonal openings under flexural loading. Various positions of openings such as along the neutral axis, above the neutral axis and below the neutral axis were considered for the study. From the experimental findings, it has been observed that the load-carrying capacity of the castellated beam with web opening above neutral axis is found to be higher compared to other configurations. Nonlinear finite element analysis was performed by using general purpose finite element software ABAQUS considering the material nonlinearities. Concrete damage plasticity model was employed to model the nonlinearity of concrete and elasto-plastic model for steel. It has been observed that FE model could able to capture the behaviour of concrete encased steel castellated beams and the predicted values are in good agreement with the corresponding experimental values.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.365-375
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• 2017

An experimental evaluation of crack propagation and post-cracking behavior in steel fiber reinforced concrete (SFRC) beams, using full-field displacements obtained from the digital image correlation technique is presented. Surface displacements and strains during the fracture test of notched SFRC beams with volume fractions ($V_f$) of steel fibers equal to 0.5 and 0.75% are analyzed. An analysis procedure for determining the crack opening width over the depth of the beam during crack propagation in the flexure test is presented. The crack opening width is established as a function of the crack tip opening displacement and the residual flexural strength of SFRC beams. The softening in the post-peak load response is associated with the rapid surface crack propagation for small increases in crack tip opening displacement. The load recovery in the flexural response of SFRC is associated with a hinge-type behavior in the beam. For the stress gradient produced by flexure, the hinge is established before load recovery is initiated. The resistance provided by the fibers to the opening of the hinge produces the load recovery in the flexural response.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.358-361
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• 2006

For giving self-diagnosing capability, a method based on monitoring the changes in the electrical resistance of carbon materials in strengthened concrete has been tested. Then after examining change in the value of electrical resistance of carbon materials used as a rib of CFGFRP or a sheet of carbon fiber before and after the occurrence of cracks and fracture in hybrid FRP or carbon fiber sheet strengthened concrete at each flexural weight-stage, the correlations of each factors were analyzed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.178-185
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• 1999

Six of scaled concrete circular columns were experimentally investigated for the contribution of arch action to the column lateral resistance. For this the specimens with the variation of tranverse hoop steel spacing were tested in absence of axial loading All specimens showed the flexure governing behavior pattern irrelevant to transverse hoop spacing. This indicates that the role of arch action should be understood as the intermediate mechanism causing the interaction between shear and flexural mechanisms A simple truss model was proposed to qualitatively explain this notation but further study is needed to advance its application to general columns.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.403-406
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• 2005

This paper deals with the propriety of the shear test data with stirrup reported in ACI and ASCE structural journal and the shear resistance characteristics affected by compressive strength of concrere($f_{ck}$), shear span-to-depth ratio (a/d), tensile reinforcement ratio($\rho$), and shear reinforcement ratio($rho_{v}$). The analysis was accomplished by the 242 shear test data. The test data include the flexural failure data around 40$\%$.

• 콘크리트학회논문집
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• 제21권6호
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• pp.737-744
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• 2009

이 연구에서는 강섬유로 보강된 초고성능 콘크리트(UHPC)의 정적재하 실험을 통하여 UHPC를 적용한 구조 부재의 휨거동 특성을 파악하고자 하였다. 부피비 2%의 강섬유를 혼입하여 철근비가 0.02 이하인 부재의 실험을 통해 주요 휨거동 특성을 파악하였다. 이 연구 결과는 추후 UHPC의 처짐산정 및 휨강도 산정 모델링에 주요한 기초 실험 자료로 활용될 수 있을 것으로 사료된다. 강섬유 보강 UHPC는 균열제어에 효과적이며, 연성지수는 6.29${\sim}$10.44 범위에서 산정되고 있어 우수한 연성거동 특성을 나타낸다. 또한 단부타설 방법으로 제작한 UHPC 보의 휨강도는 중앙타설 방법으로 제작한 UHPC의 휨강도보다 크게 나타나고 있으며, 이는 타설 방법에 의한 강섬유 배열 특성이 휨강도에 영향을 미치고 있음을 나타낸다.