Study On Stress Loss Of Prestressed TRM Reinforced Concrete Structures

At present,fiber reinforced plastic materials（FRP）such as carbon fiber,aramid fiber,and basalt fiber have been widely used in bridge reinforcement and other engineering fields.However,the traditional paste reinforcement method has great technical defects.For example,the carbon fiber material only exerts less than 20%of the strength when the tensile reinforcement is yielded.This reinforcement method cannot fully utilize the high-strength characteristics of FRP,and the reinforcement effect is limited.The prestressed FRP reinforcement technology can improve the cracking load and yield load of the member,limit the stress growth of the steel bar,etc,and it has many advantages that cannot be matched by ordinary reinforcement methods.This reinforcement method has been more and more used in reinforcement projects.However,the prestressed FRP reinforcement method has an unavoidable problem,it is called“the prestress loss”.At present,there is relatively little research on the prestress loss of this reinforcement method at home and abroad.So the study of prestress loss has very important scientific significance and engineering application value.In this paper,the reinforcement system developed by the research group was used to conduct the stress loss test of the prestressed TRM（Textile Reinforced Motar）reinforced concrete structure.At the same time,it also carry out the theoretical analysis and finite element simulation of the test process,and the following conclusions were obtained:（1）The TRM paste concrete block test was used to analyze and study the law of prestress loss caused by slip during tension,and the total loss value of the test block under different influencing factors was obtained.（2）According to the force balance relationship when the limit of the concrete beam is destroyed,the appropriate value of the maximum tensile control stress of the reinforcement method is derived in this paper.（3）In the stress loss test of TRM-reinforced concrete beams,the prestress loss mainly comes from the four stages of tension,bonding and solidification,disassembly,and long-term loss.The main factors causing these four prestress losses are fiber web slippage and anchor system deformation,the stress relaxation of the fiber web,the deformation of the tightening screw and the slideway,the shrinkage and creep of the concrete.The total prestress loss value tested can be safely taken as 15%_（89）.（4）In this paper,the calculation formulas of various prestress losses in this test are given and calculated.Comparing the calculated value with the test value,the error between them is small,and there is not much difference between them,and the accuracy and validity of the calculation formula is verified.（5）In this paper,the finite element simulation methods for the tensile process loss and stress relaxation loss are given,and compared with the test results,the errors are small,indicating the accuracy and feasibility of the two simulation methods.