DOI: 10.14457/tu.the.2015.1460
title: Strengthening of RC deep beams using glass chopped strand mat fiber

description: This thesis is aimed to investigate the techniques to externally strengthenthe reinforced concrete deep beams by using multidirectional glass chopped strandmat (GCSM) composites. In external bonded strengthening technique, the GCSMsheet was cut and attached on the surfaces of the beam by using hand lay-up method.The behavior and the failure mode of strengthened specim ens were experimentallyinvestigated. It was known that the failure mode of specimens strengthened withexternal bonded technique was mostly due to the debonding of the fiber compositesfrom the beam surfaces, therefore, various mechanical anchors were investigated andutilized to prevent the debonding failure of GCSM fiber composites. The usage ofanchors was able to improve the bond between concrete and composites, which leadsto fully usage of fiber composites.The experimental program in this study was divided into three parts. Thefirst part discusses the experimental results of six reinforced concrete deep beamsstrengthened in shear using external bonded technique. One beam was tested withoutstrengthening, while the remaining five beams were strengthened using different fiberthickness and configurations. All specimens were tested under static loading untilfailure. The comparisons between control and strengthened specimens were made anddiscussed in Chapter 4. The experimental results showed that this GCSM e xternalstrengthening technique enhances the ultimate loading capacity of the RC deep beam.The second part presents the experimental results of five reinforcedconcrete deep beams which were strengthened using external GCSM fiber compositeswith mechanical anchors. Different resin systems (i.e., polyester and epoxy resin)were used to fabricate and bond the GCSM composites to the beam surfaces by usinghand lay-up method. The experimental results indicated that providing additionalbond strength by means of mechanical anchors enhances the ultimate loading capacityof RC deep beams and leads to fully usage of the fiber composites. Epoxy resin ismore effective than polyester resin since the ultimate load of specimen strengthenedwith epoxy-bonded GCSM fiber composites was increased up to 68% compared thecontrol specimen. The behavior and failure mode of all specimens in this group werediscussed in Chapter 5.The third part shows the series of twenty reinforced concrete deep beamswhich were strengthened using external bonded GCSM fiber composites withanchors. All specimens were subjected to static loading and tested up to failure.Epoxy resin system was used as the adhesive in this study. The effects of externalbonded GCSM technique on the beams of diffierent concrete strengths and shearspan-to-depth ratios were experimentally investigated. The GCSM fiber sheets wereapplied to the beam in different amounts and configurations (i.e., Side-bonded and Uwrappedscheme). Two different types of anchors (i.e., mechanical expansion anchorand epoxy anchor) were exploited. The experimental results showed that the fiberthickness has the effect on the strengthening efficiency of external bonded GCSMcomposites for improving the ultimate strength of reinforced concrete deep beams.The U-wrapped scheme has a significant benefits compared with side-bonded scheme.The applied load versus the mid-span deflection curves of strengthened specimenwere plotted against their control specimens. The behavior and mode of failure of alltested beams were presented and discussed in Chapter 6.Chapter 7 presents the finite element analysis carried out on reinforcedconcrete (RC) deep beams strengthened in shear using Glass Chopped Strand Mat(GCSM) polymer composites. VecTor2 is a nonlinear finite element (FE) softwarewhich has been developed at the University of Toronto. FE program VecTor2 wasused for the modeling and analysis of RC deep beams externally strengthened usingGCSM fiber composites with mechanical anchors. It can be seen that the results obtained from the VecTor2 were in good accordance with the experimental results.The finite element models can predict the behavior of un-strengthened andstrengthened RC deep beams. This finite element program is also capable ofpredicting cracks at every load steps. The crack patterns of RC deep beams observedduring testing and the predicted finite lement results are compared and discussed inthe following sections.