• Advances in concrete construction
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• v.17 no.5
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• pp.273-284
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• 2024

The steel-concrete composite system has been playing a vital role in the construction sector for the past two decades. By using steel and concrete together, we achieve strong load resistance with minimal deflection and bending stress. The study focuses on the numerical and analytical behaviour of concrete encased steel castellated beams and compared them with previous experiments. The study used five composite beams, including one control reinforced concrete beam (CC), one fully concrete encased steel beam (FCES), and three fully concrete encased castellated beams. The major variable is the opening configuration of the castellated beam, such as openings along the longitudinal axis, above the longitudinal axis, and below the longitudinal axis. The 150 mm × 250 mm cross section and 2000 mm in length of beams were used. Using the finite element software ANSYS, we conduct nonlinear finite element analysis for the entire beam and compare it with test data. The numerical load carrying capacity of concrete encased steel castellated beam with a hexagonal opening above the longitudinal axis (FCESCB H2) is 160 kN is closer to the experimental observation. Von Mises strain of FCESB is 0.004232, which is lower than CB and composite castellated beam. The ductility factor and energy absorption capacity of FCESB are 5.090 and 1688.47 kNm. It was observed that the configuration of the opening will influence the strength of the composite beam. Plastic moment methods were employed to estimate the ultimate load carrying capacity of the beam. In the analytical study the beams were assumed as perfectly plastic. The ultimate analytical load carrying capacity of FCESCB H2 is 21.87% higher than FCESB. It found that performing FCESCB H2 is superior to the entire specimen.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.775-793
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• 2016

This paper presents a numerical method for estimating the curvature, deflection and moment capacity of FRP-reinforced concrete encased steel composite beams (FRP-RCS). A sectional analysis is first carried out to predict the moment-curvature relationship from which beam deflection and moment capacity are then calculated. Comparisons between theoretical and experimental results of tests conducted elsewhere show that the proposed numerical technique can accurately predict moment capacity and deflection of FRP-RCS composite beam. The numerical results also indicated that beam ductility and stiffness are improved when encased steel is added to FRP reinforced concrete beams. ACI, ISIS and Bischoff models for deflection prediction compared well at low load, however, significantly underestimated the experimental results for high load levels.

• Steel and Composite Structures
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• v.38 no.6
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• pp.705-716
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• 2021

An innovative partially precast partially encased composite beam (PPECB) is put forward based on the existing research. In order to study the flexural performance of the new composite beam which has precast part and cast-in-place part, six prefabricated specimens and one cast-in-place specimen are designed with considering the influence of the production method, the steel flange thickness, the concrete strength grade and the stirrup process on the behavior of the composite beam. Through four points loading and test data collection and analysis, the behavior of partially prefabricated specimen is similar to that of cast-in-place specimen, and the casting method, the thickness of the steel flange, the concrete strength grade and the stirrup process have different influence on the crack, yield and peak load bearing capacity of the component. Finally, the calculation theory of plastic bending of partially precast partially encased concrete composite beams is given. The calculation results are in good agreement with the experimental results, which can be used for practical engineering theory guidance. This paper can provide reference value for further research and engineering application.

• Computers and Concrete
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• v.22 no.3
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• pp.269-278
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• 2018

In the recent decades, the application of composite materials, due to their desirable properties, has increased dramatically. In the present study, a quasi-encased trapezoidal section composite steel beam encased with concrete is thoroughly examined. Calculation of the load bearing capacity is carried out by finite element modeling of concrete and FRP beams with trapezoidal section under the effect of controlled displacement loading. The results are then validated comparing to the existing experimental results obtained from similar studies. Further on, the materials are changed to steel and concrete, and the section is de-signed in such a way that both concrete and steel reach a high percent-age of their load bearing capacity. In the last step, the parameters affecting the bending capacity and the behavior of the semi-confined composite beam are investigated. Results revealed that the beam diagonal web thickness plays the most effective role in load bearing capacity amongst other studied parameters. Furthermore, by analyzing the results on the effect of different parameters, an optimal model for primary beam section is presented, which exhibits a greater load bearing capacity compared to the initial design with the same amount of materials used for both sections.

• Steel and Composite Structures
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• v.23 no.1
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• pp.17-29
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• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.398-401
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• 2006

This study investigates the behaviour of Hybrid Beam with reinforced concrete encased steel center and reinforced concrete end. Two types of encased steel shape and two sections are examined in this study. Test results showed that H-Hybrid beam is stronger than Honey-comb Hybrid beam, and the behaviour of composite beam embedded steel at the elastic state is same as that of simple beam.

• Steel and Composite Structures
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• v.47 no.3
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• pp.423-436
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• 2023

In this research, we tested 10 simply supported concrete-encased composite columns under monotonic eccentric loads and investigated their shear behaviour. The specimens tested were two reinforced concrete specimens, three steel-reinforced concrete (SRC) specimens with an H-shaped steel section (also called a beam section), and five SRC specimens with a cruciform-shaped steel section (also called a column section). The experimental variables included the transverse steel shape's depth and the longitudinal steel flange's width. Experimental observations indicated the following. (1) The ultimate load-carrying capacity was controlled by web compression failure, defined as a situation where the concrete within the diagonal strut's upper end was crushed. (2) The composite effect was strong before the crushing of the concrete outside the steel shape. (3) We adjusted the softened strut-and-tie SRC (SST-SRC) model to yield more accurate strength predictions than those obtained using the strength superposition method. (4) The MSST-SRC model can more reasonably predict shear strength at an initial concrete softening load point. The rationality of the MSST-SRC model was inferred by experimentally observing shear behaviour, including concrete crushing and the point of sharp variation in the shear strain.

• Steel and Composite Structures
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• v.29 no.6
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• pp.735-748
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• 2018

In this paper, the cyclic behavior of steel beam-concrete encased steel (CES) column joints was investigated experimentally and numerically. Three frame middle joint samples with varying concrete slab widths were constructed. Anti-symmetrical low-frequency cyclic load was applied at two beam ends to simulate the earthquake action. The failure modes, hysteretic behavior, ultimate load, stiffness degradation, load carrying capacity degradation, displacement ductility and strain response were investigated in details. The three composite joints exhibited excellent seismic performance in experimental tests, showing high load-carrying capacity, good ductility and superior energy dissipation ability. All three joint samples reached their ultimate loads due to shear failure. Numerical results from ABAQUS modelling agreed well with the test results. Finally, the effect of the concrete slab on ultimate load was analyzed through a parametric study on concrete strength, slab thickness, as well as slab width. Numerical simulation showed that slab width and thickness played an important role in the load-carrying capacity of such joints. As a comparison, the influence of concrete grade was not significant.

• Steel and Composite Structures
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• v.33 no.1
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• pp.67-79
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• 2019

Composite columns made of high strength materials have been used in high-rise construction owing to its excellent structural performance resulting in smaller cross-sectional sizes. However, due to the limited understanding of its structural response, current design codes do not allow the use of high strength materials beyond a certain strength limit. This paper reports additional test data, analytical and numerical studies leading to a new design method to predict the ultimate resistance of composite columns made of high strength steel and high strength concrete. Based on previous study on high strength concrete filled steel tubular members and ongoing work on high strength concrete encased steel columns, this paper provides new findings and presents the feasibility of using high strength steel and high strength concrete for general double symmetric composite columns. A nonlinear finite element model has been developed to capture the composite beam-column behavior. The Eurocode 4 approach of designing composite columns is examined by comparing the test data with results obtained from code's predictions and finite element analysis, from which the validities of the concrete confinement effect and plastic design method are discussed. Eurocode 4 method is found to overestimate the resistance of concrete encased composite columns when ultra-high strength steel is used. Finally, a strain compatibility method is proposed as a modification of existing Eurocode 4 method to give reasonable prediction of the ultimate strength of concrete encased beam-columns with steel strength up to 900 MPa and concrete strength up to 100 MPa.

• Steel and Composite Structures
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• v.36 no.5
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• pp.533-551
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• 2020

A finite element analysis (FEA) model is established to investigate the concrete-encased concrete-filled steel tubular (CFST) column to reinforced concrete (RC) beam joints under cyclic loading. The feasibility of the FEA model is verified by a set of test results, consisting of the failure modes, the exposed view of connections, the crack distributions and development, and the hysteretic relationships. The full-range analysis is conducted to investigate the stress and strain development process in the composite joint by using this FEA model. The internal force distributions of different components, as well as the deformation distributions, are analyzed under different failure modes. The proposed connections are investigated under dimensional and material parameters, and the proper constructional details of the connections are recommended. Parameters of the beam-column joints, including material strength, confinement factor, reinforcement ratio, diameter of steel tube to sectional width ratio, beam to column linear bending stiffness ratio and beam shear span ratio are evaluated. Furthermore, the key parameters affecting the failure modes and the corresponding parameters ranges are proposed in this paper.