Experimental Study And Finite Element Simulation On Flexural Performance Of Reinforced Concrete Beams Strengthened With Near Surface Mounted BFRP Bars

The building structure has a certain service life.Some aging buildings,due to their long life,have problems in terms of safety during use.It is more economical and feasible methods to use these reinforcement techniques to reinforce these structures or buildings so that they can continue to serve the society.The near surface mounted(NSM)technology is to groove the surface of the structure and then load the reinforcement material into the structure while filling the open groove with the cement material,the reinforcement of the structure or building can be completed,and the force performance can be improved.Compared with other reinforcing materials,BFRP has many advantages such as convenient construction,good adhesion,acid and alkali resistance,high strength,etc.It is a more excellent reinforcement material.At present,there are still few researches on the NSM with BFRP materials.This paper mainly studies the bending performance of BFRP reinforced concrete beams.In this paper,seven reinforced concrete(RC)beams were fabricated,including a contrast beam,three beams with NSM BFRP bars and primary forces,and three beams with NSM BFRP bars and secondary force.The three variables of reinforcement quantity,longitudinal reinforcement ratio and secondary force are mainly set up for experimental research.The main research work includes:(1)Through the recording of the main test data in the loading process,and observing the crack development and final damage of each test beam,it is concluded that the embedded reinforcement of the concrete beam with BFRP bars tends to significantly enhance the bending capacity of the beam and also cause cracks.The pace of development has slowed down.Appropriately increasing the reinforcement ratio of the longitudinal reinforcement and the number of reinforcement reinforcements will increase the ultimate strength of the reinforcement beam and increase the stiffness of the beam and reduce its deformation.For the secondary stressed beam,the reinforcement is carried out after preload and unloading,the beam has been damaged,after the reinforcement,the adhesion of the structural adhesive and the concrete protective layer is insufficient,which will greatly weaken the ultimate strength of the strengthened beam.(2)The The calculation formula of the mid-span deflection and the applied load of thetest beam is derived.Combined with the correlation calculation result of the bending moment-curvature relationship,the load-deflection curve of the whole process of the beam is calculated by computer programming,and compared with the curve obtained by the test result,found the calculated values are agree well with the test results.(3)Using the ATENA software,the finite element model of the beam RCB and the three primary stressed beams was established by selecting the appropriate unit and material constitutive relations.The finite element simulation of the whole process was carried out.Through the extraction and analysis of the simulation results,the simulation results and the experimental results can be well matched,and the applicability of the model is verified.It is shown that it is feasible to analyze the bending performance of the BFRP reinforced beams with nonlinear finite element method.