• Steel and Composite Structures
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• 제49권4호
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• pp.381-392
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• 2023

This study experimentally investigates the flexural behavior of steel-UHPC composite slabs composed of an innovative negative Poisson's ratio (NPR) steel plate and Ultra High Performance Concrete (UHPC) slab connected via demountable high-strength bolt shear connectors. Eight demountable composite slab specimens were fabricated and tested under traditional four-point bending method. The effects of loading histories (positive and negative bending moment), types of steel plate (NPR steel plate and Q355 steel plate) and spacings of high-strength bolts (150 mm, 200 mm and 250 mm) on the flexural behavior of demountable composite slab, including failure mode, load-deflection curve, interface relative slip, crack width and sectional strain distribution, were evaluated. The results revealed that under positive bending moment, the failure mode of composite slabs employing NPR steel plate was distinct from that with Q355 steel plate, which exhibited that part of high-strength bolts was cut off, part of pre-embedded padded extension nuts was pulled out, and UHPC collapsed due to instantaneous instability and etc. Besides, under the same spacing of high-strength bolts, NPR steel plate availably delayed and restrained the relative slip between steel plate and UHPC plate, thus significantly enhanced the cooperative deformation capacity, flexural stiffness and load capacity for composite slabs further. While under negative bending moment, NPR steel plate effectively improved the flexural capacity and deformation characteristics of composite slabs, but it has no obvious effect on the initial flexural stiffness of composite slabs. Meanwhile, the excellent crack-width control ability for UHPC endowed composite members with better durability. Furthermore, according to the sectional strain distribution analysis, due to the negative Poisson's ratio effect and high yield strength of NPR steel plate, the tensile strain between NPR steel plate and UHPC layer held strain compatibility during the whole loading process, and the magnitude of upward movement for sectional plastic neutral axis could be ignored with the increase of positive bending moment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.415-418
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• 2005

Prestressed composite girder bridges with PS tendon at positive flexural moment region offer elastic behavior to higher loads, increased ultimate capacity and reduced structural steel weight. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to positive flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.

• 한국강구조학회 논문집
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• 제26권3호
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• pp.205-217
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• 2014

본 연구에서는 인장 플랜지에 HSB 고성능 강재를 적용한 강합성 복합단면 I-거더의 정모멘트에 대한 휨저항강도 및 연성 요구조건을 검토하였다. AASHTO LRFD 설계기준에서 강합성 거더의 정모멘트에 대한 공칭 휨저항강도 및 연성 요구조건은 소성모멘트와 소성 중립축을 이용하여 규정하고 있으며, 이때 소성모멘트와 소성중립축은 일반 강재에 대하여 유도된 값이다, 하지만 응력-변형률 거동에서 일반강재와 다르게 HSB 고성능 강재의 소성영역은 명확히 정의될 수 없다. 따라서 고성능 강재의 이상화된 응력-변형률 곡선을 통해 고성능 강재의 소성영역을 가정하여 소성모멘트를 정의하였으며, 다양한 치수를 갖는 임의의 단면에 대하여 수행된 수치 해석의 결과를 통해 인장 플랜지에 HSB 고성능 강재를 적용한 강합성 복합단면 I-거더의 연성 요구조건 및 공칭 휨저항강도 산정식을 제안하였다.

• 한국강구조학회 논문집
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• 제14권2호
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• pp.357-364
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• 2002

스터드, 조이스트 및 지붕 트러스에 적용하기 위한 폐단면 냉간성형부재의 휨실험을 수행하고 해석치와 비교하여 보았다. 길이 2.4m, 폭 0.9m의 휨 시편은 46cm 간격의 두 개의 강재보의 한면에 석고보드와 합판을 부착한 시편과 부착하지 않은 시편으로 구성되었고, 각 시편에 대한 정, 부모멘트실험을 수행하여, 강재보에 부착된 합판 및 석고보드가 강재의 좌굴거동에 미치는 영향을 포함한 합성거동을 파악하였다. 또한 합판이 부착된 실물 트러스 실험을 통하여 트러스 부재의 좌굴거동 및 파괴양상에 대하여 연구하였다.

• 한국강구조학회 논문집
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• 제22권4호
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• pp.377-388
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• 2010

HSB600 및 HSB800 고성능강재를 적용한 정모멘트부 강합성거더의 휨거동을 비선형 모멘트-곡률 해석법으로 분석하였다. 연성특성이 다른 3개의 대표적인 강합성거더 기본 단면을 선정하여 모멘트-곡률 해석법으로 모멘트-곡률 이력과 휨저항강도를 구하고 비선형 유한요소해석 프로그램 ABAQUS(2008)로 구한 결과와 비교하여 모멘트-곡률 해석 프로그램을 검증하였다. 비선형 유한요소해석 시에는 플랜지, 복부판 및 콘크리트 바닥판을 판요소로 모델링하여 3차원 강합성거더 유한요소모델을 적용했으며 초기변형과 단면의 잔류응력을 고려하여 해석하였다. 강합성거더 단면에서 콘크리트 바닥판의 28일 압축강도는 30~50MPa를 고려하였으며, 콘크리트 재료는 CEB-FIP(1990) 모델로, 일반 강재와 HSB600 및 HSB800 고성능 강재는 탄소성-변형경화 재료로 모델링하였다. 강합성단면의 연성비, 강거더의 강종, 콘크리트 바닥판의 압축강도, 소성중립축의 위치 등이 강합성거더의 연성특성 및 휨저항강도에 미치는 영향을 분석하였다.

• Steel and Composite Structures
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• 제20권6호
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• pp.1369-1389
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• 2016

This paper investigates the flexural stiffness of simply supported steel-concrete composite I-beams under positive bending moment through combined experimental, numerical, and different standard methods. 14 composite beams are tested for experimental study and parameters including shear connection degree, transverse and longitudinal reinforcement ratios, loading way are also investigated. ABAQUS is employed to establish finite element (FE) models to simulate the flexural behavior of composite beams. The influences of a few key parameters, such as the shear connection degree, stud arrangement, stud diameter, beam length, loading way, on the flexural stiffness is also studied by parametric study. In addition, three widely used standard methods including GB, AISC, and British standards are used to estimate the flexural stiffness of the composite beams. The results are compared with the experimental and numerical results. The findings have provided comprehensive understanding of the flexural stiffness and the modelling of the composite beams. The results also indicate that GB 50017-2003 could provide better results in comparison to the other standards.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.385-390
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• 2001

This paper presents a nonlinear analysis technique with slip, the effects of slip modulus and composite action by shear connector on behavior and capacity in composite structure of sandwich system. As a results of this study, it proved that the slip modulus, in case of shear behavior, seldom influence load-resistance capacity such as yield and ultimate load, but in case of flexural behavior, it appropriately influence load-resistance capacity because of stress redistribution by slip. In case of flexural behavior, analysis result for perfect-composite results in over-estimation and perfect-slip results in under-estimation on behavior and capacity. Therefore, it is desirable to model steel-concrete interface with partial-composite. The effects of slip on behavior and capacity are less in case of positive composite than loosely composite, and it proved that composite action by shear connector improve the load-resistance capacity of this system.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.101-104
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• 2004

Composite beams are generally known to possess higher flexural stiffness and strength under the positive bending moments than the normal steel beams. However the these beams also exhibit large differences in flexural stiffness and strength when both positive and negative bending moments are applied. As observed during the 1995 Kobe Earthquake, these beams tend to be fractured on the bottom flanges under repeated cyclic loadings. The objective of this study is to develop and evaluate the composite beam detail, which is able to effectively resist the seismic loadings. The proposed system is composed of the slit on concrete slab around column. A limited experimental program was designed and conducted to investigate the hysteretic behavior of the proposed composite beam system. From the experimental data obtained from the testing of three specimens, the proposed composite beam detail is found to possess large beam rotation than normal steel beams.

• Steel and Composite Structures
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• 제32권1호
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• pp.21-35
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• 2019

This study investigates the flexural behavior of steel-concrete composite beams strengthened with prestressed carbon fiber-reinforced polymer (CFRP) plates. An innovative mechanical anchorage system was developed. The components of the system can be easily assembled on site before applying a prestressing force, and removed from the structures after strengthening is completed. A total of seven steel-concrete composite specimens including four simply supported beams strengthened at the positive moment region and three continuous beams strengthened at the negative moment region were tested statically until failure. Experimental results showed that the use of prestressed CFRP plates enhanced the flexural capacity and reduced the mid-span deflection of the beams. Furthermore, by prestressing the CFRP laminates, the material was used more efficiently, and the crack resistance of the continuous composite specimens at the central support was significantly improved after strengthening. Overall, the anchorage system proved to be practical and feasible for the strengthening of steel-concrete composite beams. The theoretical analysis of ultimate bearing capacity is reported, and good agreement between analytical values and experimental results is achieved.

• Steel and Composite Structures
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• 제21권4호
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• pp.829-847
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• 2016

This paper investigates the flexural capacity of simply supported steel-concrete composite I beam and box beam under positive bending moment through combined experimental and finite element (FE) modeling. 24 composite beams are included into the experiments and parameters including shear connection degree, transverse reinforcement ratio, section form of girder, diameter of stud and loading way are also considered and investigated. ABAQUS is employed to establish FE models to simulate the behavior of composite beams. The influences of a few key parameters, such as the shear connection degree, stud arrangement, stud diameter, beam length and loading way, on flexural capacity are discussed. In addition, three methods including GB standard, Eurocode 4, and Nie method are also used to estimate the flexural capacity of composite beams and also for comparison with experimental and numerical results. The results indicate that Nie method may provide a better estimation in comparison to other two standards.