• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.233-236
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• 2008

구조재로서 목재는 자연에서 쉽게 얻을 수 있는 재료로서 뛰어난 미관, 가공성 등으로 인해 전통가옥이나 사찰 등에 널리 사용되어져 왔지만, 콘크리트나 강재에 비해 연소와 부식의 우려 등 내구성에 문제를 가지고 있다. 따라서, 목재를 구조부재로 활용하기 위해서는 타 재료와의 하이브리드화가 필요하다. 따라서, 본 연구에서는 구조용집성재보(100${\times}$200${\times}$3000(mm)), 콘크리트슬래브(800${\times}$100${\times}$3000(mm), fck=21MPa) 및 전단연결재(볼트, 래그스크류)로 구성된 합성보의 탄소성거동을 평가하기 위하여 구조 실험을 수행하였다. 실험결과, 전단연결재의 종류와 간격에 무관하게 항복비(항복내력/최대내력)가 크고, 항복 후에는 바로 취성파괴로 연계되었다. 따라서, 이러한 취성파괴를 방지할 수 있는 휨보강(철근, 섬유쉬트 등)이 필요할 것으로 판단된다. 또한, 전단연결재 배치간격이 좁을수록 합성효과가 우수하여 사용성이 뛰어나기 때문에 경제적 설계와 재료의 효율적 사용이 가능할 것으로 판단된다.

• Steel and Composite Structures
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• 제44권3호
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• pp.295-307
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• 2022

The objective of this research is to study experimentally the behavior of stiffened steel tubes (CFSTs). Considered parameters are stiffening methods by through-bolts or shear connectors with different configurations. In addition, the effect of global (ratio between length to diameter) and local (proportion between diameter to thickness) slenderness ratios are investigated. Load application either applied on steel only or both steel and concrete is studied as well. Case of loading on steel only happens when concrete inside the column shrinks. The purpose of the research is to improve the behavior of CFSTs by load transfer between them and different stiffening methods. A parametric experimental study that incorporates thirty-three specimens is carried out to highlight the impact of those parameters. Different outputs are recorded for every specimen such as load capacities, vertical deflections, longitudinal strains, and hoop strains. Two modes of failure occur, yielding and global buckling. Shear connectors and through-bolts improve the ultimate load by up to 5% for sections loaded at steel with different studied global slenderness and local slenderness equal 63.5. Meanwhile, shear connectors or through bolts increase the ultimate load by up to 6% for global slenderness up to 15.75 for sections loaded on composite with local slenderness equals 63.50. Recommendations for future design code development are outlined.

• Steel and Composite Structures
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• 제45권6호
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• pp.797-818
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• 2022

Steel-precast ultra-high-performance concrete (UHPC) composite beams with demountable high-strength friction-grip bolt (HSFGB) shear connectors can be used for accelerated bridge construction (ABC) and achieve excellent structural performance, which is expected to be dismantled and recycled at the end of the service life. However, no investigation focuses on the demountability and reusability of such composite beams, as well as the installation difficulties during construction. To address this issue, this study conducted twelve push-out tests to investigate the effects of assembly condition, bolt grade, bolt-hole clearance, infilling grout and pretension on the crack pattern, failure mode, load-slip/uplift relationship, and the structural performance in terms of ultimate shear strength, friction resistance, shear stiffness and slip capacity. The experimental results demonstrated that the presented composite beams exhibited favorable demountability and reusability, in which no significant reduction in strength (less than 3%) and stiffness (less than 5%), but a slight improvement in ductility was observed for the reassembled specimens. Employing oversized preformed holes could ease the fabrication and installation process, yet led to a considerable degradation in both strength and stiffness. With filling the oversized holes with grout, an effective enhancement of the strength and stiffness can be achieved, while causing a difficulty in the demounting of shear connectors. On the basis of the experimental results, more accurate formulations, which considered the effect of bolt-hole clearance, were proposed to predict the shear strength as well as the load-slip relationship of HSFGBs in steel-precast UHPC composite beams.

• Steel and Composite Structures
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• 제3권4호
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• pp.289-306
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• 2003

A series of tests was conducted to study the behaviour of steel-composite sandwich beams under low velocity hard impact. Damage characteristic and performance of sandwich beams with different spacing of shear connector were evaluated under impact loading. Thin steel plates were used as top and bottom skins of the sandwich beams and plain concrete was used as the core material. Shear connectors were provided by welding of angle sections on steel plates. The sandwich beams were impacted at their midpoint by a hemi-spherical nose shaped projectile dropped from various heights. Strains on steel plates were measured to study the effects of impact velocity or impact momentum on the performance of sandwich beams. Spacing of shear connectors is found to have significant effects on the impact response of the beams.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.455-464
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• 2002

There is a growing demand to assess the remaining strength and endurance of existing composite steel and concrete bridge beams due to the aging infrastructure, increases in permissible vehicle weights and increases in their frequencies. As codes are generally dedicated to the design of new structures, new procedures are required to aid in the assessment of existing bridges to ensure that they are utilised to the full. In this paper, simple expressions are presented to perform partial-interaction analyses directly from full-interaction analyses, so that the beneficial effect of partial-interaction on the shear forces on the shear connectors can be utilised in assessment to extend the fatigue life of simply supported bridge beams and to determine the effect of remedial work if necessary. Use of the assessment technique is described by way of an illustrative example.

• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.211-216
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• 2002

A steel plate-concrete composite slab with pyramidal shear connectors, named TSC composite slab, is expected to have sufficient bending strength and flexural rigidity for loads during and after construction. Fatigue problems play an important role in designing composite slab as bridge decks under traffic conditions. In this paper, a series of fatigue tests was carried out on TSC beam specimens under various loading conditions, in order to evaluate the fatigue strength of TSC composite slabs. The results are as follows : (1) the fatigue failure of TSC composite beams results from the tensile fracture of bottom steel plate and shear connector, and (2) fatigue strength of the steel plate for two million cycles can be estimated to be $1144kgf/cm^2$ from the S-N curves.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.485-488
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• 2004

Steel encased composite columns have been used for buildings and piers of bridges. Since column section for pier is relatively larger than that of building columns, economical steel ratio need to be investigated for the required performance. Composite action between concrete and embedded steel sections can be obtained by bonding and friction. However, the behavior. of the column depends on the load introduction mechanism. Compression can be applied to concrete section, steel section and composite section. In this paper, experiments on shear strength of the steel encased composite column were performed to study the effect of confinement by transverse reinforcements, mechanical interlock by holes, and shear connectors. Shear strength obtained from the tests showed considerably higher than the design value. Confinement, mechanical interlock and stud connectors increased the shear strength and these values can be used effectively to obtain composite action of SRC columns.

• Steel and Composite Structures
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• 제15권3호
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• pp.299-322
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• 2013

In the case of seismic-resistant composite dual moment resisting and eccentrically braced frames, the current design practice is to avoid the disposition of shear connectors in the expected plastic zones, and consequently to consider a symmetric moment or shear plastic hinges, which occur only in the steel beam or link. Even without connectors, the real behaviour of the hinge may be different from the symmetric assumption, since the reinforced concrete slab is connected to the steel element close to the hinge locations, and also due to contact friction between the concrete slab and the steel element. The paper presents the results and conclusions of experimental tests on composite portal eccentrically braced frames and beam-to-column moment-resisting joints, carried out within the CEMSIG Research Centre of the Politehnica University of Timisoara, in order to check the validity of the assumption stated above. Reference steel and composite specimens with and without connectors in the plastic zones have been tested under monotonic and cyclic seismic type loading.

• 한국강구조학회 논문집
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• 제29권5호
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• pp.377-387
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• 2017

이 연구에서는 강판 매입형 합성기둥의 Push-out Test를 통해 강재와 콘크리트의 부착면적에 따른 영향을 알아보았다. 이로써 부착면적이 넓을수록 부착응력은 작아진다는 경향이 조사되었다. 또한 소규모 매입형 합성기둥의 경우에는 설계기준에서 제시하는 공칭부착 응력값이 과소하게 적용되는 것을 확인하였다. 다음으로 H형강 매입형 합성기둥의 Push-out Test를 통해 전단연결재의 수와 간격에 따른 영향을 알아보았다. 이로써 전단연결재의 전단거동을 파악할 수 있었다.

• Structural Engineering and Mechanics
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• 제68권4호
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• pp.485-495
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• 2018

This paper presents the results of an experimental study on the structural performance of an innovative GFRP-concrete composite beam construction, which is reinforced with longitudinal GFRP pultruded box-profile and transverse steel stirrups. GFRP perfobond (PBL) shear connectors are employed to enhance the bonding performance between the GFRP profile and the concrete portion. To investigate the shear and flexural performance of this composite system, eight specimens were designed and tested under three-point and four-point bending. The main variables were the height of the composite beam and the shear span-to-depth ratio. The test results indicated that bonding cracks did not occur at the interface between the GFRP profile and the concrete until the final stage of the test. This shows that the specimens performed well as composite beams during the test and that the GFRP PBL connectors were reliable. Based on the test results, two calculation methods were used to determine the flexural and shear capacity of the composite beams. A comparative study of the test and theoretical results suggests that the proposed methods can reasonably predict both the flexural and shear capacities of the specimens, whereas the provisions of ACI 440 are relatively conservative on both counts.