Research On Flexing Resistance Of Reinfoeced Concrete Beams Strengthened With Prestressed Near Surface Mounted CFRP Tendons And Its Anchorage System

Near Surface Mounted(NSM) firber reinforced plastic reinforcement and carbon fiber reinforced plastic(CFRP) tendons anchorage have been widespread attention at home and abroad in recent years. High-strength properties of CFRP tendons could be highly utilizated, when prestressing CFRP tendons, however, Anchorage issues affect their wide application. The paper presents a series of experimental study and theoretical analysis for anchorage system of CFRP tendons and Flexing Resistance of reinfoeced beams relying on Henan Innovation Project for University Prominent Research Talents (2007KYCX006).Based on the current characteristics of CFRP anchor tendons and the test of prestressed CFRP reinforced concrete beams, 60mm, 90mm, 2×60mm Jaw vice anchorage and 400mm, 500mm, 600mm Bonding Spherical Jaw Vice Anchorages are designed in this paper. Mechanical analysis and experimental study of anchor performance of the CFRP anchorage is studied. Based on the Flexural Behavior of concrete beam strengthened with pre-stressed near surface mounted carbon fiber reinforced plastic bar,one RC beam and nine concrete beams strengthened with pre-stressed near surface mounted CFRP tendons are studied. In these tests, stiffness, crack load, yielding load, ultimate load, crack development and ductility for experimental study of test specimens are carried out. Analysis on prestress loss of CFRP tendons, calculation model of test specimens at prestress releasing or at counteracting forces and different failure mode of ultimate load are also studied for Application in Engineering.Experimental results show that anchorage length and preload is the key factor affecting the performance of Jaw Vice Anchorage; and the length of steelpipe and performance of bond media is the key factor affecting the performance of Bonding Spherical Jaw Vice Anchorage. Spherical anchor can automatically adjust the center line of CFRP tendons and anchorage, it can change the force characteristics of the end of anchorage and reduce shear stress, and it can also improve the performance of anchorage. Experimental results show that crack load, Stiffness, ultimate load of test specimens are impvoved greatly, so this method deserves further assessment.