Abstrakt

Flexural strengthening of concrete structures using prestressed fibre reinforced polymers

Raafat El-Hacha

Fibre bolstered polymers (FRP) reinforcement has been used for flexural strengthening either as AN outwardly warranted (EB) system within the style of FRP laminate (sheets, plates or strips) applied to the side tension facet of the ferroconcrete (RC) members or as a near-surface mounted (NSM) system within the style of FRP strips or bars embedded within a pre-cut groove into the concrete cowl at the stress facet of the RC member full of epoxy adhesive. though flexural strengthening victimisation non-prestressed FRP reinforcement will remarkably increase the last word strength of a member, it doesn't considerably amendment the behaviour of the member underneath service hundreds or considerably increase the stiffness of the member. It ought to be noted that in non-prestressed FRP strengthening application solely some of the strength of the FRP reinforcement is effective and therefore the system could be a passive strengthening technique that is still inactive till extra hundreds square measure applied. to realize a rise within the stiffness of the member, the strengthening system should move instead of passive. Thus, to boost the potency of the system, the FRP reinforcement ought to be prestressed before being warranted to the concrete. Therefore, by prestressing the FRP, the fabric is employed a lot of with efficiency as a result of a larger portion of its tensile capability is used, and it contributes to the supporting capability underneath each service and supreme conditions. Prestressing the EB and NSM FRP reinforcement needs a special anchorage system that ought to be sensible in implementation. In general, prestressing is employed to reinforce the flexural behaviour of ferroconcrete members underneath service hundreds particularly in bridges and (or) beams that have massive spans and there's a limitation on the deflection and serviceableness conditions. due to their high lastingness properties, FRP materials have nice benefits to be used in prestressing and post-tensioning strengthening applications. The specialised application of prestressing the FRP reinforcement for flexural strengthening of structures combines the noncorrosive and lightweight advantages of the FRP reinforcement with the benefits related to external prestressing. However, the difficult a part of the active FRP strengthening system is that the application of the prestressing force to the FRP material victimisation acceptable sensible anchorage and prestressing system. A comprehensive review on the techniques and anchorage systems developed to prestress the EB and NSM FRP with the main target on the utility of the prestressing systems wherever the FRP is prestressed against the member itself, and therefore the performance of members reinforced victimisation prestressed FRP reinforcement square measure mentioned during this presentation.