Experimental Study On The Flexural Behavior Of The Overloading Damaged RC T-beam Strengthened With Steel Plate Under Dry-wet Environment

A number of RC bridges built in 1980s and 1990s in our country. With the booming development of road freight transport, overloading and overrun has caused irreversible damage to the old bridge, which effects their operating conditions and service life. RC beams strengthened with steel plate is one of the most accepted and widely used techniques, because it can greatly enhance the capacity of bridges and do not change the shape of bridges. However, reinforced beams under the dry-wet environments in the Pearl River Delta Area can cause corrosion of steel plate and anchor bolt, and structural adhesive aging. All of these factors can affect the durability of reinforced beams.Based on concrete T-beam model of Guangzhou Express Highway, sixteen laboratory model of RC T-beams had been processed, and using Pearl River Delta highway vehicle load spectrum for concrete beams to do overload damage test. The main researches and conclusions are as follows.(1) Theoretic Analysis of steel plate strengthened beam under consider the adhesive thickness, designing a calculation formula of the bearing capacity of steel plate strengthened RC T-beams, and through the experiment results to verify the bearing capacity calculation formula.(2) Overload damage T-beams static test results show that overload damage can improve the yield load and ultimate load of beams, because in the process of overload damage test, the steel have the effect of cold drawing, improve the bearing capacity. The overload damage can also improve the ductility of RC beams.(3) Two RC beams and four damage RC beams strengthened in flexure using the same thickness and width of the steel plate. Test results show that RC beams and damage RC beams strengthened by steel plate increase the bearing capacity were 71.4% and 74.1% respectively, the ultimate deflection of a drop of 54.6% and 52.7% respectively. After steel reinforcement, steel plates have changed the performance of damage beams and the effect of damage to improve the strength and ductility of the beam is small. Steel reinforcement can also increase the stiffness of the beam.(4) Two and third damage RC beams strengthened by steel plate were carried on 90 and 180 times dry-wet cycling test. Test results show that the bearing capacity of damage beams after 90 and 180 cycles was decreased, but the degree of the reduction was not obvious. The dry-wet cycling effect on the ductility of damage beams were more apparent, cycle several times more, the better ductility of the beam.(5) RC beams and damage RC beams strengthened by steel plate, before reinforcement yielding, the bearing capacity provided by steel and steel plate. After reinforcement yielding, increase of the load provided by steel plate.