In this study, the construction of axial load-bending moment interaction diagrams for a reinforced concrete column and a steel jacket column has been presented. For a reinforced concrete column strengthened with a steel jacket consist of vertical steel sections connected by horizontal steel plates (battens), the axial load-bending moment interaction diagrams have been constructed using two analytical methods: strain compatibility method and plastic stress distribution method. In the strain compatibility method, the effects of position of the neutral axis on the stress of concrete, reinforcing bars, and steel section have been taken into consideration. In the plastic stress distribution method, the position of the neutral axis has no effect on the stress of the three components, and the maximum value of the stress has been used for each component. The analytical results obtained by the two methods have been compared with the experimental results for some chosen experimental specimens, and they gave good agreement.
The reinforced concrete column is designed to have a nominal axial resistance. Under different conditions like errors in design, and changing the use of the building from residential to public or storage (extra live loads), the reinforced concrete column will not be able to sustain the desired applied load, and the strengthening is required. This paper presents a finite element model to simulate and investigate the behavior of adding steel jacket to a preloaded and non-damaged reinforced concrete column. Depending on the loading state of the non-strengthened reinforced concrete column and the purpose of adding the steel jacket, two possible cases have been studied. In the first case, which is suitable to investigate the reinforced c
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In this research a theoretical study has been carried out on the behavior and strength of simply supported composite beams strengthened by steel cover plate taking into consideration partial interaction of shear connectors and nonlinear behavior of the materials and shear connectors. Following the procedure that already has been adopted by Johnson (1975), the basic differential equations of equilibrium and compatibility were reduced to single differential equation in terms of interface slip between concrete slab and steel beam. Furthermore, in order to consider the nonlinear behavior of steel, concrete and shear connectors, the basic equation was rearranged so that all terms related to materials are isol
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This paper studies the behavior of axially loaded RC columns which are confined with carbon fiber reinforced polymers’ sheet (CFRP) and steel jackets (SJ). The study is based on twelve axially loaded RC columns tested up to failure. It is divided into three schemes based on its strengthening type; each scheme has four columns. The main parameters in this study were the compressive strength of the concrete and steel reinforcement ratio. Furthermore, the results of the experimental test showed a substantial enhancement in the column's load-carrying capacity. When compared to the original columns, the CFRP sheet had a significant effect on improving the ductility of the column by increasing the axial deformation by about 59.2 to 95.7
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Reinforced concrete (RC) slabs strengthened with carbon fibre reinforced polymer (CFRP) and subjected to flexural actions may experience many types of failure, including FRP debonding, FRP rupture and concrete crushing. Of these different types of failure modes, FRP debonding stands out as the most predominant type of failure because of its dependence on the relatively weak bond interface between the soffit of the RC member and the FRP sheet attached to it. Many anchorage systems have been developed to enhance the performance of strengthened systems, one of which is the hybrid anchor, which combines the effects of patch anchors and spike anchors. Hybrid anchors have shown significant enhancement when used with RC members subjected to shear
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This research is concerned to investigate the behavior of reinforced concrete (RC) deep beams strengthened with carbon fiber reinforced polymer (CFRP) strips. The experimental part of this research is carried out by testing seven RC deep beams having the same dimensions and steel reinforcement which have been divided into two groups according to the strengthening schemes. Group one was consisted of three deep beams strengthened with vertical U-wrapped CFRP strips. While, Group two was consisted of three deep beams strengthened with inclined CFRP strips oriented by 45o with the longitudinal axis of the beam. The remaining beam is kept unstrengthening as a reference beam. For each group, the variable considered
... Show MoreDue to design errors and changes in the use of buildings, reinforced concrete (RC) columns must often be strengthened to support additional live loads. The column must be designed to withstand both axial loads and bending moments, and an interaction diagram is necessary to demonstrate the column failure. The most common technique for strengthening RC columns uses a steel jacket consisting of four steel angles and battens. In this study, another strengthening technique was proposed that uses two steel C-sections with steel battens. A new approach for constructing an axial force-bending moment interaction diagram for RC columns strengthened with steel C-section jackets using an analytical model based on the plastic stress distribution
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