• Steel and Composite Structures
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• v.24 no.6
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• pp.689-695
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• 2017

The constitutive relation is an important factor in analysis of confined concrete in composite structures. In order to propose a constitutive model for nonlinear analysis of confined concrete, lateral restraint mechanism of confined concrete is firstly analyze to study the generalities. As the foundation of the constitutive model, peak stress and peak strain is the first step in research. According to the generalities and the Twin Shear Unified Strength Theory, a novel unified equation for peak stress and peak strain are established. It is well coincident with experimental results. Based on the general constitutive relations and the unified equation for peak stress and peak strain, we propose a unified and convenient constitutive model for confined concrete with fewer material parameters. Two examples involved with steel tube confined concrete and hoop-confined concrete are considered. The proposed constitutive model coincides well with the experimental results. This constitutive model can also be extended for nonlinear analysis to other types of confined concrete.

• Computers and Concrete
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• v.23 no.4
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• pp.295-301
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• 2019

In this paper, buckling analyses of composite concrete plate reinforced by piezoelectric nanoparticles is studied. The Halphin-Tsai model is used for obtaining the effective material properties of nano composite concrete plate. The nano composite concrete plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of concrete plate are obtained and using Hamilton's principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of piezoelectric nanoparticles volume percent, geometrical parameters of concrete plate and elastic foundation on the buckling load are investigated. Results showed that with increasing Piezoelectric nanoparticles volume percent, the buckling load increases.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.549-552
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• 1999

Recently, a variety of uses for combined reinforced concrete and steel have been applied in actual construction, which are called hybrid structures. The purpose of the hybrid construction is the high-efficiency of structural behaviors. But the design method of SRC is relatively complicated design method. So, it hasn't detailed design method yet and we are depending upon foreign specifications. In this study, To develop the design method of SRC at the condition of composite behaviors, makes process about major factors that affects the composite behaviors. And we suggested fundamental data of the composite behaviors by experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.447-450
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• 2005

A prefabricated composite hollow slab with perforated I-beams was suggested for the replacement of deteriorated concrete decks or the construction of new composite bridges with long-span slabs. Composite slabs with embedded I-beams have considerably higher stiffness and strength. For the application of prefabricated composite slabs to bridges, joints between slabs should satisfy the requirements of the ultimate limit state and the serviceability limit state. In this paper, three types of the detail for loop joints were selected and their structural performance in terms of strength and crack control was investigated through static tests on continuous composite slabs. A main parameter was the detail of the joint, such as an ordinary loop joint and loop joint with additional reinforcements. Even though there was no connection of the steel beams at the joints, the loop joints showed good performance in terms of strength. In terms of crack control, the loop joint with additional reinforcements showed better performance. In ultimate limit state, the continuous composite slabs showed good moment redistribution and ductility.

• Structural Engineering and Mechanics
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• v.85 no.5
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• pp.573-592
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• 2023

This paper presents a careful theoretical investigation into interfacial stresses in composite aluminum-slab reinforced concrete beam bonded by a prestressed hybrid carbon-glass composite material. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, i.e., the aluminum beam, the slab reinforced concrete, the hybrid carbon-glass composite plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. Numerical results from the present analysis are presented both to demonstrate the advantages of the present solution over existing ones and to illustrate the main characteristics of interfacial stress distributions. It is shown that the stresses at the interface are influenced by the material and geometry parameters of the composite beam. This research is helpful for the understanding on mechanical behaviour of the interface and design of the hybrid structures.

• Steel and Composite Structures
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• v.19 no.2
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• pp.293-308
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• 2015

Interaction between the external thin-walled steel tube and the internal concrete core significantly increases the bending resistance of composite beams and beam-columns in comparison with the steel or concrete members. There is presented a developed method for design of hollow and solid concrete-filled steel tubular beams based on test data, which gives better agreement with test results than EC4 because its limitation to take an increase in strength of concrete caused by confinement contradicts the recommendation of 6.7.2(4) that full composite action up to failure may be assumed between steel and concrete components of the member. Good agreement between the results of carried out experimental, numerical and theoretical investigations allows recommending the proposed method to use in design practice.

• International Journal of Highway Engineering
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• v.16 no.2
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• pp.91-98
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• 2014

PURPOSES : The objective of this study is to investigate the effect of asphalt and geotextile interlayer on the fracture behavior of unbonded concrete overlay through a laboratory composite beam test. METHODS : In order to evaluate the effect of interlayer materials on the fracture behavior of unbonded concrete overlay, a laboratory test of composite beam was conducted with different types of interlayer. The test results of the composite beam using two types of geotextile interlayer with different thicknesses were compared to the test results of the composite beam using the tradition type of asphalt interlayer. The unbonded concrete overlay on the existing concrete pavement without interlayer was set for the control condition. RESULTS AND CONCLUSION : Overall, the laboratory composite beam test results did show the effect of asphalt and geotextile interlayer on the fracture behavior of composite concrete beams. The three-layer geotextile interlayer and HMA layer both increase the peak load when the first macrocrack occurs in the top concrete beam, while the HMA interlayer causes the smallest load drop percentage after the first macrocrack. The three-layer geotextile did show better performance than the single-layer geotextile through the greater peak load and smaller load drop percentage. It indicates that the thickness of geotextile interlayer will affect the fracture behavior of unbonded concrete overlay and the thicker geotextile interlayer is recommended.

• Steel and Composite Structures
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• v.36 no.5
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• pp.507-519
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• 2020

Double skin composite walls are increasingly popular and have been applied to many safety-related facilities. They come from the concept of composite slabs. Conventional connectors such as shear studs and binding bars were used in previous studies to act as the internal mechanical connectors to lock the external steel faceplates to the concrete core. However, the restraint effects of these connectors were sometimes not strong enough. In this research, a recently proposed unique type of steel truss was employed along the wall height to enhance the composite action between the two materials. Concrete-filled tube columns were used as the boundary elements. Due to the existence of boundary columns, the restraints of steel faceplates to the concrete differ significantly for the walls with different widths. Therefore, there is a need to explore the effect of height-to-width ratio on the structural behavior of the wall. In the test program, three specimens were designed with the height of 3000 mm, the thickness of 150 mm, and different widths, to simulate the real walls in practice. Axial compression was applied by two actuators on the tested walls. The axial behavior of the walls was evaluated based on the analysis of test results. The influences of height-to-width ratio on structural performance were evaluated. Finally, discussion was made on code-based design.

• Structural Engineering and Mechanics
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• v.59 no.2
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• pp.261-275
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• 2016

Effect of silica fume on fresh properties, compressive strength at 28 days and fracture behavior of fly ash concrete composite were studied in this paper. Test results indicated that the fluidity and flowability of fly ash concrete composites decreased and fly ash concrete composite are more cohesive and appear to be sticky with the addition of silica fume. Addition of silica fume was very effective in improving the compressive strength at 28 days of fly ash concrete composite, and the compressive strength of fly ash concrete composite has a trend of increase with the increase of silica fume content. Results also indicated that all the fracture parameters of effective crack length, fracture toughness, fracture energy, the critical crack opening displacement and the maximum crack opening displacement of fly ash concrete composite decreased with the addition of silica fume. When the content of silica fume increased from 3% to 12%, these fracture parameters decreased gradually with the increase of silica fume content. Furthermore, silica fume had great effect on the relational curves of the three-point bending beam specimen. As the silica fume content increased from 3% to 12%, the areas surrounded by the three relational curves and the axes were becoming smaller and smaller, which indicated that the capability of concrete composite containing fly ash to resist crack propagation was becoming weaker and weaker.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.48-56
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• 2013

Prestressed concrete (PSC) members are readly available in civil engineering applications due to the convenience of construction and easy of quality control in the manufacturing process of the member. Especially, half-depth precast concrete composite slab, which is one of the PSC flexural members is developed recently using the long-line method. The half-depth precast concrete composite slabs are composed of the precast concrete and the in-situ concrete placed at the site. In this paper, we present the results of experimental investigations pertaining to the pretensioning efficiency and the flexural behavior of half-depth precast concrete composite slab which is made of precast PSC manufactured by the long-line method. In the long-line method, the pretensioned precast member is manufactured simultaneously, by tensioning tendons at once. In addition, we suggest the equation that can estimate the flexural strength of half-depth precast concrete composite slab reasonably by considering the effects of rebar embedded in the precast PSC flexural member.