Based on a comparison of the advantages and disadvantages of existing strengthening methods, this paper proposes a new strengthening technique with prestressed high-strength steel wire rope (P-SWR) for reinforced concrete (RC) beams. The paper presents the theoretical basis of this new method, an experimental programme of flexural strengthening of RC beams with P-SWR, and a comparison between the results of experimental tests on the proposed methods and the results for a carbon-fibre-reinforced polymer (CFRP) sheet and steel plate. The effectiveness parameters, including the loading method (direct loading or pre-damaged loading), the layers of steel wire rope, bonding or lack of bonding between the steel wire and concrete, and the types of anchorage are discussed. Test results show that the P-SWR can significantly improve the cracking load, stiffness, yield load and ultimate load of RC beams. The final failure model for the beams strengthened with P-SWR has typical characteristics, such as steel yielding, crushed concrete and fractured steel wire ropes. The width of flexural cracks in the concrete beams is effectively controlled. This method also exploits the strain capacity of the wire rope to its limits. Furthermore, the advantages of this new technique include minimum site disruption, minimal increase in the size of the repaired member, minimum scaffolding, superiority for fire and corrosion resistance, and low cost; the method presented is therefore an attractive alternative to existing strengthening methods.

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2014) Flexural strengthening of RC beams using distributed prestressed high strength steel wire rope: theoretical analysis, Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance, 10:2, 160-174, Various strengthening techniques for structural elements using different materials have been investigated. Recently, a new, reliable and cost-effective strengthening technique with distributed prestressed high strength steel wire rope (P-SWR technique) was proposed. This paper mainly focuses on theoretical analysis of the flexural behaviour of reinforced concrete (RC) beams strengthened with the P-SWR strengthening technique. First, mechanical properties of steel wire rope such as ultimate strength, ultimate tensile strain and relaxation were tested. Second, an evaluation method, including the prediction of cracking load and flexural capacity of RC beams strengthened with P-SWR, was proposed. Third, prestressed level of P-SWR, ratio of reinforcement, and bond strength of P-SWR and concrete responsible for short-term cross-sectional stiffness were studied and associated calculation equations are suggested. Finally, according to parametric studies, an entire evaluation system, including a modified Rao & Dilger code calculation method and hypothetical tension method, as well as a simplified method for predicting the maximum crack width, is proposed. All of these analytical procedures are based on experimental studies. A great similarity between the experimental and analytic results suggests that the proposed methods are highly accurate.

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