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Review by:Lin Jia Tsui

Progress on Understanding Debonding Problems in Reinforced Concrete andSteel Members Strengthened Using FRP CompositesIntroductionFiber Reinforced Plastic (FRP) now is commonly use in structural strengthening. It caused by:

Occuring of debonding failure in interface between concrete and FRPThere are many researches that done the experiment relate to this problem.

problemthen3 FRP strengthening of RC and steel member

There are may research have found that combination of FRP as externally bonded of RC member repair the fatigue damage of steel member.All of the structure member can use FRP as strengthed to this member such as beam to increase axial, flexural or shear load capacities. But another important role is the debonding problem that have impact to the behavior and the performance of this beam.

Elastic and strength properties of FRP composites compared with conventional construction materials,

Failure mode of FRP strengthened flexural RC

Failure mode of FRP strengthened flexural steel member Debonding problems in FRP strengthened RC and steel member

Type of debonding in FRP strengtened RC membersType of debonding in FRP strengtened steel membersPrevious experimental by Kaiser revealed that CFRP plate can use to strengthen RC beam and debonding of FRP reinforcement occurred in the concrete substrate and mode of failure is in premature load level with very brittle failure.

More followed researches then revealed that debonding failure can caused by improper of adhesive. Moreover, behavior of debonding failure depend on the reinforcement ratio and also the type of FRP that used.

Then the experimental by author about the repairing side-notched steel speciment by FRP patches in various configuration result the increasing their fatigue lives. Another experimental study by the author revealed that both failure and ductility of precracked beam can increase through shear strengthening and bond anchorage by using FRP strengthened. EXPERIMENTAL RESEARCH ON DEBONDING PROBLEM

Influence of shear strengthening and anchorage on strengthened beam behavior under monotonic loadingModeling Research on Debonding ProblemThere are many research studies that have begun to focus on the modeling of debonding problem in FRP strengthened RC member due to the critical issue. They make relative simple model to get easier implementation and calculation.use the calculation of interfacial bond stress distribution based on elastic material properties by comparing stresses with ultimate strength of material the assumption all of materials are linearly elastic

basically debonding is a crack propagation promote by local stress use elastic and fracture material properties with the system behavior based on fatigue propagation various research use developing analytical and FEM to determine stress intensities in the repair system to predict fatigue damage

Strength ApproachFractureApproachthis model is simple method without using the complex stress or fracture analysis but use approaches of phenomenological basis to predict failurebased on shear capacity of the strengthened beam with assume that material will fail when the shear in a beam exceed the predefine value.this method reffer to the concrete tooth models

Semi- empirical and empirical model

Concrete tooth modelCyclic Loading dan Environmental Effect on Debonding impact

Influence of shear strengthening and anchorage on FRP strengthened beam behavior under cyclic loading (a) flexural (b) flexuralqshear (c) flexuralqshearqanchorage.Environmental effects on debonding FRP are superior environmental resistance

problemConclusionDebonding of FRP strengthened RC is the major problem in structural strengthening.Strengthening RC by using FRP externally bonded is one of the effective tecniques. Although there are many aspects that have to be considered and calculated such as the environmental exposure and also high-amplitude cyclic load performance of these system.IntroductionFiber Reinforced Plastic (FRP) now is commonly use in structural strengthening. It caused by:

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