Study On The Replaceable Strengthening Method Of Beam Structures

Because of the improper operation of forwarders and the deficiency of highway transport management, vehicle overloading is becoming a more and more common problem. The long-term reciprocating effect of vehicle load is causing great fatigue damage to bridge structures, and causing the reduction of reliability and safety of bridges.In order to cope with the problem of beam bridge fatigue damage caused by vehicle load, a new strengthening method is proposed.The replaceable strengthening method of beam structures is achieved by using both prestress CFRP plate and bolted steel plate. The prestress CFRP plate is permanent strengthening component, and the bolted steel plate is replaceable strengthening component. In this new method, second-strengthening is taken into account before the design of the strengthening program.After the first-strengthening, resistance of the structure is increased. The bridge may face the deficiency of resistance after serving for another period of time. Then, the steel plate is to be replaced to make the bridge recover to a better condition. By repeating this procedure, the life endurance of the bridge will be expanded, and the life cycle cost of the bridge will be reduced. The damage to the bridge is reduced because of the existence of steel plate, and the service life of the bridge can be expanded because of the exchange of the steel plate.The main contributions of this paper are listed as follows:(1) The response of a bridge structure under vehicle loading is introduced. By explaining the damage of bridge structures caused by vehicle fatigue load, the necessity of developing the replaceable strengthening is pointed out.(2) The fatigue theory of RC structure, along with the S-N curve and resistance decline mode of steel bar, is introduced, which is the theoretical basis of this paper.(3) The replaceable strengthening method of beam structures is proposed. The theoretical derivation is accomplished, and a case is given to explain the whole strengthening method.By exploring this strengthening method, we hope a new economic and reliable strengthening method can be developed, and make breakthrough on the new method of structure strengthening.