• Structural Engineering and Mechanics
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• v.84 no.3
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• pp.311-321
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• 2022

In the buildings with long spans and high floors, such as logistics warehouses and semiconductor factories, it is difficult to install supporting posts under beams during construction. Therefore, the size of structural members becomes larger inevitably, resulting in a significant increase in construction costs. Accordingly, a prestressed hybrid wide flange (PHWF) beam with hollowed steel webs was developed, which can reduce construction costs by making multiple openings in the web of the steel member embedded in concrete. However, since multiple openings exist and prestress is introduced only into the bottom flange concrete, it is necessary to identify the shear resistance mechanism of the PHWF beam. This study presents experimental shear tests of PHWF beams with hollowed steel webs. Four PHWF beams with cast-in-place (CIP) concrete were fabricated, with key variables being the width and spacing of the steel webs embedded in the concrete and the presence of shear reinforcing bars, and web-shear tests were conducted. The shear behavior of the PHWF beam, including crack patterns, strain behavior of steel webs, and composite action between the prestressed bottom flange and CIP concrete, were measured and analyzed comprehensively. The test results showed that the steel web resists external shear forces through shear deformation when its width is sufficiently large, but as its width decreased, it exerted its shear contribution through normal deformation in a manner similar to that of shear reinforcing bars. In addition, it was found that stirrups placed on the cross section where the steel web does not exist contribute to improving the shear strength and deformation capacity of the member. Based on the shear behavior of the specimens, a straightforward calculation method was proposed to estimate the web-shear strength of PHWF beams with CIP concrete, and it provided a good estimation of the shear strength of PHWF beams, more accurate than the existing code equations.

• International Journal of Concrete Structures and Materials
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• v.10 no.sup3
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• pp.109-121
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• 2016

Recently, as the use of high-performance materials and complex composite methods has increased, the need for advanced design specifications for steel-concrete composite structures has grown. In this study, various design provisions for ultimate flexural strengths of composite beams were reviewed. Design provisions reviewed included the load and resistance factor design method of AISC 360-10 and the partial factor methods of KSSC-KCI, Eurocode 4 and JSCE 2009. The design moment strengths of composite beams were calculated according to each design specification and the variation of the calculated strengths with design variables was investigated. Furthermore, the relationships between the deformation capacity and resistance factor for flexure were examined quantitatively. Results showed that the design strength and resistance factor for flexure of composite beams were substantially affected by the design formats and variables.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.19-20
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• 2013

Green Frame is a column-beam system constructed by composite precast column and beam connected by embedded steel of their. From when the precast concrete beam of Green Frame is installed, until the concrete of slab and connection joint is cured, the self load of beam shall be supported by the embedded steel of it. Therefore, the concrete of beam could be separated from the embedded steel if the shear connector of beam of Green Frame is designed by the code on Structural standard. So, this study suggest an equation for the shear connection of composite precast concrete beams of Green Frame. The result of this study will be used as the main equation of the calculation model for shear connectors of composite precast concrete beams.

• Steel and Composite Structures
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• v.20 no.6
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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.

• Steel and Composite Structures
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• v.14 no.4
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• pp.313-333
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• 2013

The web-encased steel-concrete composite (WESCC) beam is a new developed steel-concrete composite beam. Experiments of six simply supported WESCC beam specimens were conducted. The effects of the shear-span ratio and steel section type were all investigated on the static behaviors such as failure modes, failure mechanism and bearing capacity. The experimental results denoted that all specimens failed in bending mode and the degree of combination between the bottom armor plate of steel shape and concrete were very well without any evident slippage, which demonstrated that the function of bottom armor plate and web were fully exerted in the WESCC beams. It could be concluded the WESCC beams have high stiffness, high load carrying capacity and advanced ductility. The design methods are proposed which mainly consist the bearing capacity calculation of bending and flexural rigidity. The calculation results of the bearing capacity and deflection which take the shear deflection into account are in agreement with the experimental results. The design methods are useful for design and application of the innovative composite beams.

• Steel and Composite Structures
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• v.27 no.3
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• pp.355-370
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• 2018

In steel-concrete composite beams, longitudinal shear forces are transferred across steel flange-concrete slab interface by means of shear connectors. The connector behavior is highly non-linear and involves several complex mechanisms. The design resistance and stiffness of composite beams depends on the shear connection behavior and the accuracy in the connector resistance prediction is essential. However determining the stud shear resistance is not an easy process: analytical methods do not give an adequate response to this problem and it is therefore necessary to use experimental methods. This paper present a summary of the main procedures to predict the resistance of the stud shear connectors embedded in solid slab, and stud shear connectors in composite slab using profiled steel sheeting with rib perpendicular to steel beam. A large number of experimental studies on the behavior of stud shear connectors and reported in the literature are also summarized. A comparison of the stud shear resistance prediction using six reference codes (AISC, AASHTO, Eurocode-4, GB50017, JSCE and AS2327.1) and other procedures reported in the literature against experimental results is presented. From this exercise, it is concluded that there are still inaccuracies in the prediction of stud shear resistance in all analysed procedures and that improvements are needed.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.565-570
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• 1997

This study is on the strength capacity and the strengthening effects of crarbon fiber sheets(CFS) and glass fiber sheets (GFS) on steel reinforced concrete(SRC) beams. SRC beams are often used on high-rise building construction to save story height and construction cost. However, there are no strengthening design code in Korea and most engineers design it as steel beams ignored the composite effect if reinforced concrete. Test results on steel reinforced concrete beams reveal thar the strength capacity of SRC beam is more than simple addition of steel and reinforced concrete beams. In case of steel reinforced concrete beams, ultimate moment capacity of strengthening beam of carbon fiber sheets is 120% of non-strengthening one.

• Computers and Concrete
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• v.15 no.3
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• pp.437-459
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• 2015

An experimental investigation on the behaviour of geopolymer composite concrete beams reinforced with conventional steel bars and various types of fibres namely steel, polypropylene and glass in different volume fractions under flexural loading is presented in this paper. The cross sectional dimensions and the span of the beams were same for all the beams. The first crack load, ultimate load and the loaddeflection response at various stages of loading were evaluated experimentally. The details of the finite element analysis using "ANSYS 10.0" program to predict the load-deflection behavior of geopolymer composite reinforced concrete beams on significant stages of loading are also presented. Nonlinear finite element analysis has been performed and a comparison between the results obtained from finite element analysis (FEA) and experiments were made. Analytical results obtained using ANSYS were also compared with the calculations based on theory and presented.

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.751-763
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• 2019

Steel-concrete composition is widely used in the construction due to efficient utilization of materials. The service load behavior of composite structures is significantly affected by cracking, creep and shrinkage effects in concrete. In order to control these effects in concrete slab, an efficient and novel strategy has been proposed by use of fiber reinforced concrete near interior supports of a continuous beam. Numerical study is carried out for the control of cracking, creep and shrinkage effects in composite beams subjected to service load. A five span continuous composite beam has been analyzed for different lengths of fiber reinforced concrete near the interior supports. For this purpose, the hybrid analytical-numerical procedure, developed by the authors, for service load analysis of composite structures has been further improved and generalized to make it applicable for composite beams having spans with different material properties along the length. It is shown that by providing fiber reinforced concrete even in small length near the supports; there can be a significant reduction in cracking as well as in deflections. It is also observed that the benefits achieved by providing fiber reinforced concrete over entire span are not significantly more as compared to the use of fiber reinforced concrete in certain length of beam near the interior supports in continuous composite beams.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.553-563
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• 1997

A procedure is being developed for bolting plates to the sides of existing reinforced concrete beams to strengthen and stiffen them. Unlike standard composite steel and concrete beams in which there is longitudinal-partial-interaction at the steel/concrete interface (that is slip along the length of the beam), composite bolted side-plated reinforced-concrete beams are unique in that they also exhibit transverse-partial-interaction, that is slip transverse to the length of the beam. In this work, the fundamental mathematical models for transverse-partial-interaction and its interaction with longitudinal-partial-interaction are developed. The fundamental models are then further developed to determine the number of connectors required to resist the transverse forces and to limit the degree of transverse-partial-interaction in bolted side-plated reinforced concrete beams.