The Shear Performance Of Reinforced Concrete Beam Strengthened With NSM CFRP Reinforcement

In recent years,the research and application of FRP materials have become the focus of civil engineering.Strengthening technology include externaly bonded and Near-surface Mounted.It is getting more and more attention in the civil engineering.Near-surface Mounted of FRP reinforcement has the following characteristics:(1)It need less time;(2)The FRP is not being corroded and worn out;(3)The FRP can be a good way,when the external bonded FRP is strengthening difficult in Near-surface Mounted.For example,high temperature and wet engineering.Now,NSM strengthening is infancy in our country.At abroad,there are many cases with NSM strengthening.At present,there are many research on the flexural strengthened with NSM technology.The shear performance of concrete beam strengthened with NSM CFRP is presented.In this paper,the shear performance of 16 beams(2 control beam,14 strengthening beam).The accuracy of the simulation is verified by comparing the simulated and test data of the 5 beams.The factors of reinforcement angle of CFRP strips,spacing of CFRP strips,shear span ratio and load condition are analyzed.On the basis of the truss arch model,the calculation formula of shear capacity of reinforced concrete beams strengthened with NSM of CFRP strips is presented.The simulation value of the shear ultimate bearing capacity agree well with the test value.The ultimate bearing capacity of CFRP strip embedding angle 45?of beams are greater than 90?of beams.The spacing of CFRP strips is small but the ultimate bearing capacity is high.The loading history of one time and two times have no effect on the ultimate bearing capacity.Shear span ratio is large but the ultimate bearing capacity is low.Steel stirrup and CFRP strip strain is small at the early stage of the load but strain increases obviously when the load is high.The calculation results agree well with the simulation results.