Experimental Study On Flexural Performance Of Reinforced Concrete Beams Strengthened With BFRP Sheet Under Chloride Condition

With the urban infrastructure has been completed,many buildings will reach the design service life at present.Due to the aging of materials、Design and construction defects、unreasonable use and many so on factors that lead to its use function can not meet existing norms and standards,the focus of civil engineering has also gradually shifted to the reinforcement and repair of the active service structure.In recent years,the emergence and development of new materials,the Fiber-Reinforced Polymer have obtained much attention,because of it’s light weight,high strength,good durability and convenient construction.Basalt fiber reinforced composite material(BFRP)has a higher cost-effective,in the existing building reinforcement to get more and more applications.In this paper,we analysed the impact of the overall mechanical of reinforced concrete beams strengthened with basalt fiber sheets and the bond behavior between BFRP plate and concrete through experiment.The main contents and conclusions of this paper are as follows:1.Experimental study on mechanical properties of both fibers BFRP and GFRP-reinforced composite material operates in a different role in different saline soaked days.The results show:The Mechanical properties of BFRP plate decreased significantly after immersed in salt environment for 60 days,and the 3.5%salt solution concentration had the most significant influence on the mechanical properties of BFRP plate.2.Study on the interfacial bond property of BFRP plate reinforced concrete bonding specimens in the 10%salt concentration,And through the static load test study of the stress transfer plate.The results show:(1)the maximum strain is appearing at the loading end before stripping.The strain increases with the increase of the distance from the loading end,and far away from the loading end the strain is almost zero.So,the effective bond length of BFRP plate is about 180mm.(2)after the deterioration of the salt environment,the specimen transferred from the concrete to the interface layer and the concrete layer.It shows that the salt environment has adverse effect on the interface between BFRP and reinforced concrete.So,improving the binding force on interface layer and concrete should be paid attention.3.Researching the mechanical performance of the reinforced concrete beam reinforced by BFRP board under the different salt concentration.BFRP strengthened beams soaked in different concentrations of salt for 60 days,120 days and 180 days.And the static load test shows that:(1)the solution concentration accelerates the corrosion of the reinforced concrete beams,and the corrosion degree increases with the increase of immersion time.After 180 days of immersion in the salt environment,the maximum bearing capacity of the beam is close to 25.4%.(2)During the experiment,the effect of high concentration of salt water was obvious,and the effect of low concentration of salt water was obvious in the later experiment.(3)Under the action of salt environment,the BFRP plate reinforced beam The concrete strain distribution is still in line with the plane section assumption across mid-span section.The height of neutral axis move up with the increase of salt concentration.4.To summarize and analyze the existing calculation method of the flexural strength of the existing cross section.According to the test results,the corrosion effect of the salt concentration coefficient τ1 and the influence coefficient of deterioration τ2,and reference to the relevant literature,the salt environment under the action of the strengthened beams were stripped of the bearing capacity calculation formula is given,and the theoretical calculation with the formula,found that the calculated value and the test value is relatively small compared to the discrete.