Reliability Analysis Of CFRP-Strengthened RC Beams Under Preload Level

The reliability research of concrete beam reinforced with CFRP cloth is current researchhotspot. The emphasis of this dissertation is to research CFRP-strengthened RC beam’sbehavior under preload level, which include the deformation properties in serviceability limitstate and stress characteristics in an ultimate limit state; applying structural reliability theory,it can analyzes and deduces the reliability of reinforced RC beam, which is in the normal uselimit state and bearing capacity limit state.From two aspects of the reinforced beam’s crack and deflection, this dissertation discussesthe deformation performance problems of normal use stage. For serviceability limit state’scrack width, this dissertation sees it as two parts: one part of crack width is attributed to notreinforced beam under the external loads, which produces it; another part is, under theincreased loads based on the original, produced by CFRP-strengthened beam, this part is twoadjacent interstitial CFRP cloth’s elongation. For deflection of normal use stage, thisdissertation introduces an notion of additional curvature and argues that ordinary beam has anadditional curvature under the same load, compared with reinforced beam. This is becauseCFRP cloth can make the reinforced beam’s rigidity higher than ordinary’s, and curvature less.Based on the study of the stress of bearing capacity limit state, this dissertation analyzes theCFRP-strengthened beam’s debonding strength. According to the limit state’s condition: themaximum interfacial bonding shear stress reaches the interfacial bonding strength, we canestablish a formula of debonding strength.Based on the reinforced beam’s theoretical analysis,which is about to crack width，deflection and stripping bearing capacity, this dissertation analyzes the reliability’scharacteristics. In the serviceability limit state, this dissertation uses center point method tocalculate the crack width and deflection’s reliability indexes. In an bearing capacity limitstate, the reliability index of debonding strength is derived by checking point method. Finallythis dissertation get the two limit state’s reliability indexes.