• Steel and Composite Structures
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• 제20권6호
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• pp.1183-1191
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• 2016

The internal crack propagation, the failure mode and ultimate load bearing capacity of the steel-concrete-steel composite beam under the four-point-bend loading is investigated by the numerical simulation. The results of load - displacement curve and failure mode are in good agreement with experiment. In order to study the failure mechanism, the composite beam has been modeled, which part interface interaction between steel and concrete is considered. The results indicate that there are two failure modes: (a) When the strength of the interface is lower than that of the concrete, failure happens at the interface of steel and concrete; (b) When the strength of the interface is higher than that of the concrete, the failure modes is cohesion failure, i.e., and concrete are stripped because of the shear cracks at concrete edge.

• 한국구조물진단유지관리공학회 논문집
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• 제13권3호통권55호
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• pp.145-154
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• 2009

강합성 절곡 바닥판 중에서 I형강으로 보강된 강합성 절곡 바닥판은 절곡바닥판내에 I형강을 매입시켜 기존의 현장타설 RC바닥판보다 경량화되고 시공성을 향상시킨 바닥판이다. 현재 일반적인 철근콘크리트 구조물의 유효휨강성에 대한 계산은 도로교설계기준 및 ACI에서 제안하고 있는 방법을 사용하고 있다. 본 연구에서는 도로교설계기준 및 ACI에서 제안된 유효휨강성에 대한 산정 방법을 Ι형강으로 보강된 강합성 절곡 바닥판에 적용하여 그에 대한 적용성을 평가하고 철근콘크리트 바닥판과 비교를 하였다. 또한 실험변수로써 스터드의 유무, 지간의 변화, 단면의 형태, 부재연결방법에 걸쳐 4가지 변수를 두고 총 15개의 실험체를 제작하여 실제의 휨강성과 ACI에서 제안된 식에 의해 계산된 유효휨강성을 비교, 분석하였다.

• Steel and Composite Structures
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• 제20권1호
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• pp.57-70
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• 2016

The predominant type of buckling that I-steel concrete composite beams experience in the negative moment area is distortional buckling. The key factors that affect distortional buckling are the torsional and lateral restraints by the bottom flange. This study thoroughly investigates the equivalent lateral and torsional restraint stiffnesses of the bottom flange of an I-steel concrete composite beam under negative moments. The results show a coupling effect between the applied forces and the lateral and torsional restraint stiffnesses of the bottom flange. A formula is proposed to calculate the critical buckling stress of the I-steel concrete composite beams under negative moments by considering the lateral and torsional restraint stiffnesses of the bottom flange. The proposed method is shown to better predict the critical bending moment of the I-steel composite beams. This article introduces an improved method to calculate the elastic foundation beams, which takes into account the lateral and torsional restraint stiffnesses of the bottom flange and considers the coupling effect between them. The results show a close match in results from the calculation method proposed in this paper and the ANSYS finite element method, which validates the proposed calculation method. The proposed calculation method provides a theoretical basis for further research on distortional buckling and the ultimate resistance of I-steel concrete composite beams under a variable axial force.

• Steel and Composite Structures
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• 제21권3호
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• pp.679-688
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• 2016

Structural design of a composite beam is influenced by two main factors, strength and ductility. For the design to be effective for a composite beam, say an RC slab and a steel I beam, the shear strength of the composite beam and ductility have to carefully estimate with the help of displacements between the two members. In this investigation the shear strengths of steel-concrete composite beams was analyzed based on the respective variable parameters. The methodology used by ANFIS (Adaptive Neuro Fuzzy Inference System) has been adopted for this purpose. The detection of the predominant factors affecting the shear strength steel-concrete composite beam was achieved by use of ANFIS process for variable selection. The results show that concrete compression strength has the highest influence on the shear strength capacity of composite beam.

• Steel and Composite Structures
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• 제10권5호
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• pp.373-383
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• 2010

This paper presents the experimental studies of the flexural behavior of steel-concrete composite beams. Herein, steel-concrete composite beams were constructed with a welded steel I section beam and concrete slab with different material strength. Four simply supported composite beams subjected to two-point concentrated loads were tested and compared to investigate the effect of high strength engineering materials on the overall flexural response, including failure modes, load deflection behavior, strain response and interface slip. The experimental results show that the moment capacity of composite beams has been improved effectively when high-strength steel and concrete are used. Comparisons of the ultimate flexural strength of beams tested are then made with the calculated results according to the methods specified in guideline Eurocode 4. The ultimate flexural strength based on current codes may be slightly unconservative for predicating the moment capacity of composite beams with high-strength steel or concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.493-498
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• 2003

The 3D nonlinear analysis for steel-concrete hybrid deck is carried out by utilizing 2D plane interface element. The effect of the slip occurred between steel and concrete can be modeled by this element. This analysis focuses on not only global behavior of steel-concrete hybrid deck but also local behaviors of members of it such as lower steel plate, I-beam, and concrete which are varied by slip modulus. In this analysis, it was founded that the limit slip modulus could classify the states of steel-concrete hybrid deck into three parts such as full-composite, partial-composite, and non-composite, considering the behavior of lower steel plate, I-beam, and concrete at the mid span and the support as well as the yield load and ultimate load of it.

• Steel and Composite Structures
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• 제21권5호
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• pp.981-997
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• 2016

To avoid the cracks of cast-in-place concrete in shear pockets and seams in the traditional composite beam with precast decks, this paper proposed a new type of prefabricated steel truss-concrete composite beam (ab. PSTC beam) with pre-embedded shear studs (ab. PSS connector). To study the initial cracking load of concrete deck, the development and distribution laws of the cracks, 3 PSTC beams were tested under hogging moment. And the crack behavior of the deck was compared with traditional precast composite beam, which was assembled by shear pockets and cast-in-place joints. Results show that: (i) the initial crack appears on the deck, thus avoid the appearance of the cracks in the traditional shear pockets; (ii) the crack of the seam appears later than that of the deck, which verifies the reliability of epoxy cement mortar seam, thus solves the complex structure and easily crack behavior of the traditional cast-in-place joints; (iii) the development and the distribution laws of the cracks in PSTC beam are different from the conventional composite beam. Therefore, in the deduction of crack calculation theory, all the above factors should be considered.

• Steel and Composite Structures
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• 제10권3호
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• pp.223-243
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• 2010

This paper reports recent developments concerning the application of Generalised Beam Theory (GBT) to the structural analysis of steel-concrete composite bridges. The potential of GBT-based semi-analytical or finite element-based analyses in this field is illustrated/demonstrated by showing that both accurate and computationally efficient solutions may be achieved for a wide range of structural problems, namely those associated with the bridge (i) linear (first-order) static, (ii) vibration and (iii) lateral-torsional-distortional buckling behaviours. Several illustrative examples are presented, which concern bridges with two distinct cross-sections: (i) twin box girder and (ii) twin I-girder. Allowance is also made for the presence of discrete box diaphragms and both shear lag and shear connection flexibility effects.

• Steel and Composite Structures
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• 제42권5호
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• pp.671-683
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• 2022

To investigate and predict the long-term time-dependent behavior, such as creep, shrinkage, and relaxation of PS strands, and prestress loss in prestressed steel-concrete composite beams, named Precom, full-scale tests were conducted and the collected data were compared with those obtained from the two proposed analytical models. The combined effective modulus method (EMM)-empirical model proposed with a flowchart considered the creep effect to determine the prestress loss. Conversely, the age-adjusted effective modulus method (AEMM) with CEB-FIP equation was developed to account for the concrete aging. The results indicated that the AEMM with CEB-FIP model predicts the long-term behavior of Precom effectively.

• Steel and Composite Structures
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• 제34권1호
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• pp.91-105
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• 2020

Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.