Optimizing the strengthening and reinforcement of concrete beams by the use of CFRP filament winding

Abstract

For the flexural strengthening of reinforced concrete elements an innovative technique, based in thefilament winding method and using carbon fibres and epoxy resin, has been developed.Increases in static, dynamic, impact loading, as well as increased seismic activity, whenever designerrors have been made or structures ageing prematurely, are a few of the reasons why it is necessaryto make the rehabilitation and strengthening of concrete structures. New techniques are emerging asan alternative to steel plate bonding. One of which involves strengthening existing concrete structureswith externally bonded of pre-manufactured FRP composite materials plates, or as unidirectionalcarbon tissues to be impregnated and cured in-situ, for flexural strengthening and, occasionally, forimprovements in shear capacity.The application of the filament winding technique for this purpose provides an interestingimprovement in flexural, compression and shear capacity of concrete beam elements.To study the application of the winding process for the rehabilitation and strengthening of concretestructures, an experimental research programme and a numerical finite elements method analysisshas been done bearing in mind the strengthening of scale-reduced beams.The study of winding parameters to optimize the CFRP reinforcing system has been able when testedin three and four points bending to increase more than the double of the ultimate load of the concretebeam, providing a large deflection as well.The strengthening process will be described.