Study On Shear Capacity Of Damaged Concrete Beams Reinforced With BFRP

Due to the daily use of reinforced concrete structure,the erosion of natural disasters,man-made damage and other factors,the structure has irreversibly been damaged in varying degrees,which makes it lose its function in service life.If some important buildings are demolished,the economic value will inevitably be lost,resulting in a serious waste of resources,which is contrary to the national policy requirements on the construction industry.Reinforcement technology has emerged as the times require.It has become an important subject to use reasonable reinforcement method to repair the building structure,to restore its function and to continue to serve us.It has been developed from the most primitive mechanical strengthening technology to the strengthening technology of fiber reinforced composite material(FRP),which is of high quality and light strength,and has been unanimously recognized,and has also been gradually applied in engineering practice.Because of the variety of FRP and reinforcement technology,there are few reports on the research results of damaged beams,while the research on strengthening technology is mainly focused on the surface bonding method.Therefore,the research on the strengthening performance of basalt fiber reinforced composites and the research on damaged beams are insufficient.More experiments and theoretical research are needed.This paper mainly collects and collates the experimental data and conclusions of the experiment done by the research group.Then the shear bearing capacity of 14 damaged concrete beams are analyzed theoretically.There are single reinforcement methods and mixed reinforcement methods.Through summing up,the increase of shear bearing capacity after strengthening is analyzed under the influence factors of shear span ratio and reinforcement mode.And the failure mode of test is discussed at the same time.The feasibility and stability of the reinforcement method are verified.The theoretical analysis methods of reinforced concrete beams strengthened by FRP are summarized,and the calculation formula of shear capacity is deduced through the theory of softening tension and compression bar model.The technical rules of shear bearing capacity of reinforced concrete beams strengthened with FRP are collected in various countries and regions at home and abroad.The shear bearing capacity is calculated according to Chinese code and American code.And the calculated results are compared with the experimental results,and the conclusions are as follows: the results obtained from the two codes are conservative;Compared with other codes,China Code GB50608-2010 takes into account the bond strength between BFRP cloth,peel coefficient of BFRP cloth and the influence coefficient of secondary force on the reinforcement after damage.Therefore,the calculated results are closer to the experimental values than that of the American standard ACI440.2R-2.However,the discrete type is larger than the American norm.The calculated results obtained by the softening tension and compression bar model are the closest to the test results and the stability is better.