CFRP prestressing tendons stiffness of reinforced concrete beams Study

With the social development , the majority of the old bridge can not meet the increasing traffic demand , there are varying degrees of damage , affecting the normal performance , it takes an appropriate reinforcement of measures to enhance the applicability of the bridge , the bridge increases useful lives, to meet the needs of social development . Prestressing reinforcement method technology is one of many ways the most effective methods of reinforcement , reinforcement and other methods, which is an active reinforcement method , CFRP ( carbon fiber reinforced plastic composite ) rib reinforcement technology into full play the CFRP reinforced material material advantages, the field is expected to reinforce the bridge wide range of applications . Currently, externally prestressed concrete beam stiffness under normal use checking There are two main ways, first refer to \consider externally prestressed reinforced concrete beams secondary effects derived theoretical formula . In this paper, external prestressing CFRP tendons reinforced concrete beams experiment to study the concrete strength , the original beam reinforcement ratio , external prestressing beam bending angle , the degree of damage and load levels on the stiffness of reinforced concrete beams . By studying the following conclusions : With the original beam reinforcement to improve , CFRP prestressing tendons reinforced concrete beam stiffness increases, after yielding the original steel beams , this law is more obvious ; generally improved with concrete grade , strengthened beam stiffness has increased to some extent ; with the degree of damage and the original beams with load level increases, the strengthened beam span deflection increases, the stiffness decreases ; CFRP tendons bend angle less than 10 ° , in during normal use of the vertical stiffness of the beam is not significant . Looking at the results from the calculation , consider the secondary effects of the calculation results more accurate results than the norms settled , and this is taken into account in the calculation of the original beam damage with cracks after reinforcement stiffness reduction , the calculated results and experimental results closer and with a certain safety margin , research on CFRP prestressing tendons reinforcement technology has a certain reference.