Experiment Research On Stiffness Of Reinforced Concrete Beam With CFRP

With the development of society, the majority of the old Bridges cannot meet the increasing traffic demand, are already exist different degrees of injury, affected the normal use of performance, so need to an appropriate reinforcement measures to increase suitability, increase the bridge use fixed number of year of bridge, meet the needs of social development.Many external prestressing technology is the most effective method of consolidation method, one of the reinforcement method with other reinforcement method is different, it is a kind of active strengthening methods, CFRP reinforcement reinforcement technique fully made use of the CFRP reinforced material material advantages, is expected to begin in a wide range of bridge reinforcement field. At present, in vitro prestressed concrete beams under normal use of state of stiffness checking to basically have two kinds of methods, one is referring to the unbonded prestressed concrete structures with technical specification without adhering prestressed concrete in the stiffness calculation formula, it is to fully consider externally prestressed reinforced concrete beams second effect of the theoretical calculation formula is deduced.This article through the external prestressing tendons CFRP reinforced concrete beam was studied, and the original beams concrete label reinforcement ratio, the external prestress bend Angle, and bring load level on which the influence of reinforcing beam stiffness. Through studying the following conclusions:as the original beams, the greater the CFRP reinforced the reinforcement of externally prestressed tendons increase the stiffness of reinforced concrete beams reinforced yield, the original beams, this law after more obvious; Overall with the improved, reinforcement concrete label in the cross beam deflection decreased; As the original beams and bring load level which increase the midspan, reinforced beams increase, stiffness decreased; deflection CFRP reinforcement bend Angle in less than 10°, in normal use the phase beams effect isn't significant vertical stiffness.From the calculation results, consider the second-order effect calculation results more accurate than normative settlement results, and based on the calculation in considering the original beams strengthened with crack damage reduction stiffness discount, the calculation results with the measured results more close, and has certain security reserves of CFRP reinforcement, the research results in vitro prestressed strengthening technology has certain reference.