Study On Shear Behaviour Of RC Beam Retrofitted By Prestressed Closed Wire Rope Units

As new strengthening technology, prestressed closed wire rope units(PCWRU) strengthening can effectively enhance the shear capacity, deformation capacity and ductibility of RC beam, and it exhibits wide prospect in the field of structural rehabilitation. In order to study the engreening application of PCWRU technology, following studies were carried out: (1) Experimental researches on developing anchorage and their property were carried out; (2) RC beams retrofitted by PCWRU were tested under shear load; (3) Combining the truss model and tested results, formulas to calculate the ultimate shear bearing capacity of RC beams retrofitted by PCWRU were proposed.Six different types of anchorage were developed, and the parameters included geometries, cofigurations and groove types. Test results show heteromorphic-groove anchorages have better anchoring property and less slip while in the same geometry. Compared with the other anchorages, and undee anchorage can alleviate the damage degree effectively to wire rope units and have the best anchoring effect. So it could be applied in the PCWRU strengthening.Researches on five specimens retrofitted by PCWRU and one control specimen of RC beam were carried out, and the parameters were ratio of wire rope units, prestress level and anchoring type including undee anchorage and holding fixture anchoring. Test restults show PCWRU could enhance the ultimate shear capacity of specimens significantly, as well as deformation capacity and ductibility. Shear capacity changes differently following the wire ratio and the prestress level, the shear capacity goes up as the wire ratio increases, while it goes up and then down as the prestress level increases.Two different anchoring systems have little effect on the retrofitting effect. Based on phenomenons and results of the test, using classic truss model, the shear resistant mechanism retrofitted by PCWRU was analysed. Considering the effect of wire ratio and prestress level, formulas were proposed to calculate the ultimate shear capacity, and the calculated results show good agreement with the tested ones.