• Steel and Composite Structures
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• v.27 no.3
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• pp.297-310
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• 2018

A simple and efficient numerical optimization approach for the lightweight optimal design of composite laminated beams is presented in this paper. The proposed procedure is a combination between the finite element method (FEM) and a global optimization algorithm developed recently, namely Jaya. In the present procedure, the advantages of FEM and Jaya are exploited, where FEM is used to analyze the behavior of beam, and Jaya is modified and applied to solve formed optimization problems. In the optimization problems, the objective aims to minimize the overall weight of beam; and fiber volume fractions, thicknesses and fiber orientation angles of layers are selected as design variables. The constraints include the restriction on the first fundamental frequency and the boundaries of design variables. Several numerical examples with different design scenarios are executed. The influence of the design variable types and the boundary conditions of beam on the optimal results is investigated. Moreover, the performance of Jaya is compared with that of the well-known methods, viz. differential evolution (DE), genetic algorithm (GA), and particle swarm optimization (PSO). The obtained results reveal that the proposed approach is efficient and provides better solutions than those acquired by the compared methods.

• Steel and Composite Structures
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• v.37 no.4
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• pp.431-446
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• 2020

This paper presents the flexural performance of double skin composite beams (DSCBs) at different Arctic low temperatures. 12 DSCBs were prepared and tested under two-point loading at different Arctic low temperatures of 20, -30, -50, and -70℃. The studied parameters include low-temperature level (T), steel-faceplate thickness (t), shear span ratio (λ), and spacing of headed studs (S). The experimental investigations under two-point loading tests showed that flexural failure occurred to all DSCBs, even including the specimen designed with the small λ ratio of 2.9. The ultimate strength behaviours of DSCBs were improved due to the improved mechanical properties of constructional materials and the confinement on shear connectors. The DSCB subjected to two-point loading and low temperatures exhibits a five-stage working mechanism. The stiffness and strength indexes of DSCBs increase linearly with temperature and t value increasing, while decreasing as shear span ratio boosts. In the contrast, the change of S value from 150 to 200 mm has little effect on the ultimate strength behavior of DSCB.

• Steel and Composite Structures
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• v.44 no.5
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• pp.707-720
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• 2022

In the present work, bending and free vibration analyses of multilayered functionally graded (FG) graphene platelet (GPL) and fiber-reinforced hybrid composite beams are carried out using the parabolic function based shear deformation theory. Parabolic variation of transverse shear stress across the thickness of beam and transverse shear stress-free conditions at top and bottom surfaces of the beam are considered, and the proposed formulation incorporates a transverse displacement field. The present theory works only with four unknowns and is computationally efficient. Hamilton's principle has been employed for deriving the governing equations. Analytical solutions are obtained for both the bending and free vibration problems in the present work considering different variations of GPLs and fibers distribution, namely, FG-X, FG-U, FG-Λ, and FG-O for beams having simply-supported boundary condition. First, the matrix is assumed to be strengthened using GPLs, and then the fibers are embedded. Multiscale modeling for material properties of functionally graded graphene platelet/fiber hybrid composites (FG-GPL/FHRC) is performed using Halpin-Tsai micromechanical model. The study reveals that the distributions of GPLs and fibers have significant impacts on the stresses, deflections, and natural frequencies of the beam. The number of layers and shape factors widely affect the behavior of FG-GPL-FHRC beams. The multilayered FG-GPL-FHRC beams turn out to be a good approximation to the FG beams without exhibiting the stress-channeling effects.

• Steel and Composite Structures
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• v.20 no.2
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• pp.413-429
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• 2016

A theoretical method to predict the interfacial stresses in the adhesive layer of reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The analysis provides efficient calculations for both shear and normal interfacial stresses in reinforced concrete beams strengthened with composite plates, and accounts for various effects of Poisson's ratio and Young's modulus of adhesive. Such interfacial stresses play a fundamental role in the mechanics of plated beams, because they can produce a sudden and premature failure. The analysis is based on equilibrium and deformations compatibility approach developed by Tounsi. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the reinforced concrete beam and bonded plate. The paper is concluded with a summary and recommendations for the design of the strengthened beam.

• Structural Engineering and Mechanics
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• v.10 no.3
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• pp.227-243
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• 2000

In a companion paper, tests on bolted side plated beams have shown that side plates can substantially increase the strength of existing reinforced concrete beams with little if any loss of ductility and, furthermore, induce a gradual mode of failure after commencement of concrete crushing. However, it was also shown that transverse interaction between the side plates and the reinforced concrete beam, that is vertical slip and which is a concept unique to side plated beams, is detrimental. Transverse interaction increases the forces on the bolt shear connectors and, hence, weakens the beam. It also reduces the ability of the composite plated beam to yield and, hence, to attain its full flexural capacity. The generic concept of transverse interaction will be described in this paper and the results used to develop a new form of rigid plastic analysis for bolted side plated beams which is illustrated with an application.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.55-62
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• 1999

For the efficient performance of steel and composite building structures subjected to strong earthquake, one of current research investigates the cyclic behavior of open-web composite beams. Both experimental test and nonlinear FEM analysis demonstrate their behavior so ductile that four T-sections around the corners of rectangular web-opening develop plastic hinges prior to potential brittle failure at the beam end, i.e. at the column face. This research proposes simplified equations for determining strength and initial stiffness of composite beams with a rectangular web-opening, and compares its results with those of experimental test and nonlinear FEM analysis.

• Steel and Composite Structures
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• v.9 no.4
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• pp.349-366
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• 2009

The composite slim beam has become popular throughout Europe in recent years and has also been used on some projects in China. With its steel section encased in a concrete slab, the steel-concrete composite slim beam can provide the floor construction with minimum depth and high fire resistance. However, the design method of the T-shape steel-concrete composite beam is no longer applicable to the composite slim beam with deep deck for its special construction, of which the present design models are not available but mainly depend on experiences. The elevation of the flexural stiffness and bending capacity of composite slim beams with deep deck is rather complicated, because the influences of many factors should be taken into account, such as the variable section dimensions, development of cracks and non-linear characteristics of concrete, etc. In this paper, experimental investigations have been conducted into the flexural behavior of two specimens of simply supported composite slim beam with deep deck. The emphases were laid on the bonding force on the interface between steel beam and concrete, the stress distribution of beam section, the flexural stiffness and bending capacity of the composite beams. Based on the experimental results, the reduction factor of equivalent stress distribution in concrete flange is suggested, and the calculation method of flexural stiffness and bending capacity of simply supported slim beams are proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.293-296
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• 2006

The results and interpretations of push-out tests on shear connector devices for composite bridges carried out in this study are presented. The devices under investigations are headed studes, perfobond rib, ㄱtype perfobond rib, T- Connector and a new type of shear connector called T type perfobond rib. This new connector is flat steel plate with a number of holes punched through. The results obtained indicate that the T type perfobond rib shear connectors exhibit adequate ductility and substantially higher capacities. Therefore for composite beams utilizing reinforced concrete slabs, the T type perfobond rib shear connectors is a viable alternative to the headed studs.

• Steel and Composite Structures
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• v.50 no.6
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• pp.643-658
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• 2024

The main aim of this study is to quantify the code seismic design coefficients of the RCS system, which consisted of reinforced concrete columns and steel beams, based on the FEMA P-695 methodology. The underlying intention is to evaluate the seismic performance of the RCS system at the system level rather than the connection level. A set of 24 archetype buildings with a various number of stories, beam span lengths, gravity load levels, and seismic load levels are selected and designed based on the prevailing code requirements. Nonlinear analytical models are developed and validated by experimental tests. The pushover and response history dynamic analyses are conducted to evaluate the required data in the performance quantification process. The results show that the design coefficients suggested by the code are acceptable. However, the level of conservatism is very high. Thus, it is possible to use a larger R-factor in the design process or make some relaxations in the design requirements related to this structural system.

• KIEAE Journal
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• v.11 no.1
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• pp.9-14
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• 2011

Currently, the multi-residential apartments used in Korea are mostly bearing wall apartments which don't satisfy consumers for the lack of architectural plan flexibility. And due to remodelling-incompatible, bearing wall apartments have to be reconstructed. It is, thus, necessary to develop multi-residential apartments utilizing composite beam that can replace the conventional bearing wall-type apartment buildings. Composite beams proposed in this paper ensure modification of space and quality control, while the floor heights are maintained at the same floor height as in bearing wall structures. This study analyzes the experimental behavior of composite beams with proper combination of structural steel, reinforced concrete, and precast concrete. By comparing with the theoretical analysis and experimental results, the accuracy of flexural moment capacity and neutral axis was evaluated. The experiments were performed by two simply-supported specimens using loading and unloading. When the analysis results were compared with the experimental results, the flexural moment capacity of the composite beam was shown with an error of approximately -0.5 to 0.1% at the maximum load limit state.