Experimental study of RC beams strengthened with distributed prestressed high-strength steel wire rope

摘要

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.