Research On Flexural Behavior Of Recycled Aggregate Concrete Beam Reinforced With BFRP Rebars

The basalt fiber reinforced bars(BFRP bars)have the characteristics of high strength,light weight and corrosion resistance,etc.If the BFRP bars are applied to the building structures,it can not only reduce the corrosion of the steel bars and the weight of the building structures,but also can improve the bearing capacity of the structure.Recycled aggregate is composed of waste concrete,which is broken,washed and graded.The recycled concrete,which is formed by whole or part of recycled aggregate,plays an important role in protecting environment,saving resources and ecological construction.In this paper,BFRP bars and recycled concrete are combined together to fabricate the BFRP bar-reinforced recycled concrete beams.It can solve the problem of steel bars corrosion and the waste of natural aggregates.Therefore,the study on the flexural behavior of recycled concrete beams with BFRP rebars has certain theoretical and engineering value.In this paper,the flexural behavior of seven recycled concrete beams reinforced with BFRP rebars and one recycled concrete beam reinforced with ordinary steels are investigated.In addition,the influences of BFRP reinforcement ratio and replacement ratio of recycled aggregate on the flexural behavior of recycled aggregate concrete beam reinforced with BFRP rebars are studied.Experimental results show that the cracking point is the turning point of the load-deflection curves and the load-longitudinal reinforcement curves of the test beams and all the above curves present bilinear.The ultimate bearing capacity of the beam increases gradually and the maximum deflection,the width of cracks reduce gradually with the increase of reinforcement ratio of BFRP rebars.The influence of the replacement ratio of recycled aggregate on the flexural behavior of beams is not as obvious as the influence of BFRP reinforcement ratio.Furthermore,the differences between the recycled aggregate concrete beam reinforced with ordinary steels and the recycled aggregate concrete beam reinforced with BFRP rebars are analyzed.Based on the existing codes,the initial crack load,ultimate load,load-deflection curves and width of cracks of the recycled aggregate concrete beams reinforced with BFRP rebars are calculated.The feasibility of the existing norms on the flexural behavior of recycled aggregate concrete beams reinforced with BFRP rebars is validated by comparing the results of experimental and theoretical calculation.Last,the large software ANSYS is used to establish a 3D finite element model of the recycled aggregate concrete beams reinforced with BFRP rebars.The developed FE models which based on the test data and the numerical simulation of the bending process is carried out.Results show that the load-midspan deflection,morphology and distribution of cracks are consistent with the test results.Based on above analysis,the influences of several parameters(eg.the section height of beam,the types of FRP bars and the types of loads)on the flexural behavior of recycled aggregate concrete beams reinforced with FRP rebars are take into account.The simulation results will provide references for the further studies of the FRP bar-reinforced concrete beams.