Study On The Method For Calculating Shear Capacity Of Beams Strengthened With Wire Rope

With externally prestressed wire rope units strengthening RC beams is a kind of new technology, the wire rope material itself has a low cost, operability, higher durability; it changes the traditional passive reinforcement, while strengthens beams with initiative prestressing force. But the shear capacity calculation methods of the rope external prestressing beams have been inconclusive. This paper through shear test data analysis of3contrast beams and12RC beams Strengthened with externally prestressed wire rope, the failure mode of reinforced beams, the body stirrups strain and external wire rope strain variation, the load-deflection relationship and the factors that affect the shear capacity (including the shear span ratio, reinforcement ratio and concrete strength) were systematically analyzed. Based on it, the role of wire rope in resistance to shear failure was summarized. Considered the main factors, apply truss-arch superposition model and explain which range of application distinguished with the shear span ratio, on this basis to establish such a model, and pose the shear capacity formula. A comparative analysis between calculation with several other specifications and truss-arch superposition model is shown. The research results show that through the comparison of mechanical properties between contrast beams and reinforced beams, the failure modes of reinforcement beams no fundamental changes. But in the incline crack development process, wire rope not only delay development of incline crack but also delayed the development of deflection, so it effectively diminish the shift on the neutral axis, thereby increasing the compression area of concrete, concrete play a greater role in the process of reinforced concrete beam to resist shear. Reinforcement beam shear failure mechanism is similar to web reinforcement beams, so it can use truss-arch model to explain, the wire rope play the role of the vertical tie bar, which is similar with stirrup; On the basis of the arch-truss model, this paper propose external prestressing reinforcement beam shear capacity calculation formula. For the main factor of shear span ratio, the formula range of applications was illustrated. By comparison with the14reinforced beams test results, calculation value are good agreement with the results, which illustrates the arch-truss model to calculate the shear capacity of wire rope reinforcement RC beam is correct. Compare formula calculation result proposed by this paper to several other specifications, the calculation accuracy of this paper is higher, so illustrates this approach reasonable again.