Experimental Study On Bending Resistance Properties Of RC Beams Strengthened With BFRP

At present,there are a large number of concrete structures in our country due to the aging of materials,load changes and other reasons needing for a certain degree of reinforcement and repair.Fiber reinforced plastic have been widely used in the strengthening and reconstruction of structures for their outstanding mechanical properties,good durability and convenient construction.In order to study the impact of different layers of BFRP,the different types of U hoop anchorage and the different amount of steel plate on the bending performance of reinforced concrete beams,RC beams bonded with BFRP are experimentally investigated.The related conclusions are as follows:(1)Compared with the reference beam,the crack loads,yield loads,ultimate loads of the beams reinforced with BFRP were increased with vary degrees.The ultimate loads were respectively increased by 8%(1 layer),23%(2 layers),29%(3 layers).With the use of BFRP,the strengthening effect of RC beam is obvious.(2)Comparing the bearing capacity of RC beams with different bonding layers,we can find that with the increase of fiber layers,the bearing capacity of RC beams is also rising,but the degree of improvement is not proportional to the number of layers.Setting the U type hoops can effectively prevent the BFRP from peeling off,but they are not obvious to improve the bearing capacity of the strengthened beam.(3)The use of BFRP can effectively inhibit the development of cracks.Compared with the reference beam,there are many cracks in the reinforced beam,the average crack spacing is small,the crack distribution is more uniform,and the crack development is slow.(4)Based on the analysis of the load deflection curve,we can find that the stiffness of RC beams strengthened with BFRP is improved to some extent.And with the increase of fiber layers,the stiffness is increased more obviously.Setting U type anchors have a little effect on the stiffness of RC beam.However,they can effectively restrain the early peeling of the basalt fiber reinforced plastic,increase the deflection of the reinforced beam and improve the ductility of the beam.(5)Composite rehabilitation with bonded BFRP and steel plate can make up for the shortage of single material reinforcement method.Not only they can effectively improve the stiffness and bearing capacity of damaged concrete beams,but also can better improve the ductility of concrete structure.(6)Finally,the calculation formulas of normal section bearing capacity of reinforced concrete beams strengthened with BFRP under different failure modes are derived.The test results show that the calculated values of the ultimate bearing capacity are in good agreement with the measured values,and the calculated results are quite safe.