Study On Crack Resistance And Self-healing Of PC Simply-supported Beam Bridge

Prestressed concrete (known as PC) simply-supported beam bridge is the mostwidely used bridge. The strengthening of the concrete is an important job after thecompletion, which costs a significant amount of human labor and financial resource torepair or demolish and reconstruct after every year. Smart concrete is an increasinglywidely used material in the project area. The smart concrete is made by attaching a newFRP repair template, which comprises repairing layer and composite fiber layer, to thebottom of concrete beams. The repairing layer can repair the cracks in concrete structuretimely. As the protect layer, FRP layer can improve crack resistance of concrete beamsas well as prevent the repairing layer from outside. External bonding FRP is a traditionalreinforcement method while early debonding usually happens, which results in lowtensile performance of FRP material utilization. To address premature debondingproblems, many anchoring methods such as adding u-shaped hoop at the end of theplate, the application of the near surface mounted FRP (NSM) and mechanicallyfastening system (MF-FRP) can’t prevent early debonding completely. The earlydebonding does not take full advantage of material properties. Besides, most of the earlydebonding belongs to brittle fracture which is a great threat to the security of thestructure.This paper focuses on the interface of FRP-concrete layer. Through the analysis ofthe boundary layer properties and adhesion mechanism, try to get an interface for betteradvantage of adhesion. Chapter3and4do some bending test by concrete specimensreinforced by bonding basalt fiber. By adjusting type of adhesive, treating interface ofconcrete, embedded parts in interface, tests have been done to record destruction loadand analysis of debonding, to find the cause of different forms of debonding. Severalconclusions could be obtained by the testing as follows:①A new method of interface treating called pre-split. Spread on surface ofconcrete wrapped in a layer of bone glue-liquid (2~3mm).While water in the fluidevaporates and nice bonding property of concrete, stripping laitance and low strengthconcrete layer on the surface. In the end it gets roughness and strength interface whichis superior to the original one. Specimens treated by pre-split have better performance.②Compare between polyurethane rubber and epoxy resin adhesive, confirmedthat using soft adhesive (1/20~1/5of shear stiffness of normal one) can inhibit theintermediate crack debonding. ③While the interfacial bonding strength of the concrete is good enough,debonding of the plate end interface can be avoided. Specimen will be eventually ICdebonding in case of shear behavior of structure is sufficient, and with higher damagedloads than traditional one.④Interface embedded parts can improve debonding load, while avoiding concretecover removal.