Flexural Behaviour Of Partially Bonded Cfrp Strengthened Concrete T Beams

Download or read book Flexural Behaviour of Partially Bonded CFRP Strengthened Concrete T-beams written by Han Tae Choi and published by . This book was released on 2008 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fibre-reinforced-polymer (FRP) composites have been widely used for the flexural strengthening of reinforced concrete (RC) structures. Flexural strengthening methods with FRP include external bonding of FRP composites (EB system) and insertion of FRP strips or bars into grooves cut into the concrete (near-surface-mounted or NSM system). Recently, a prestressed FRP strengthening system has been developed and investigated, whereby the FRP reinforcement is pretensioned prior to attachment to the concrete to maximize the use of the high tensile strength of the FRP reinforcement. Existing studies have shown that the ultimate load carrying capacity and serviceability were greatly improved in FRP flexural strengthened beams. However, the only disadvantage of the FRP strengthening system is the reduction of deformability compared to that of unstrengthened structures due to the limited strain capacity of the FRP reinforcement and premature debonding failure. Structures with low deformability may fail suddenly without warning to evacuate, resulting in catastrophic failure. Therefore, a study on the improvement of deformability is critical for the effective use of FRP strengthening systems. In this study, a partially bonded concept is introduced and applied to various FRP strengthening methods, with the specific objective of increasing deformability in FRP strengthened beams. The FRP reinforcement is usually completely bonded to the concrete tensile surface, while a portion of the FRP length is intentionally unbonded in the partially bonded system in order to improve deformability while sustaining high load carrying capacity. To investigate the general behaviour of the partially bonded system, a new analytical model has been developed because conventional section analysis used for analysis of the fully bonded system is not applicable due to strain incompatibility at the FRP reinforcement level within the unbonded length. The analysis shows that a partially bonded system has a high potential to improve deformability without the loss of strength capacity.