Flexural and shear strengthening of RC beams using GFRP-SSWM hybrid wraps

Abstract

The construction industry is now expanding rapidly and, therefore, the repair and retrofitting of the concrete structures have become an essential job for many of the structures. The necessity to increase the strength of the structure so that it can withstand the design loads in case of structural degradation or to carry the additional load due to changes in use or change in codal requisites is mentioned. Externally bonded fiber reinforced polymer (FRP) is one of the most frequently applied methods for strengthening and retrofitting the already existing concrete structure. The FRP materials are carbon FRP (CFRP), glass FRP (GFRP), aramid FRP (AFRP), basalt FRP (BFRP) and they have the advantage over the traditional repair materials in the field of better strength and durability performance and they are also easier to construct. The application of CFRP and GFRP, on the other hand, makes structure stronger, but because of the brittle tensile behaviour and debonding problems their strength is not fully exploited.Thus, it is necessary to find an alternative material for FRP, which is more ductile and have better bond characteristic. Locally available Stainless Steel Wire Mesh (SSWM) bonded on a concrete surface with an epoxy resin is explored as an alternative material for strengthening of structural element. In this study combination of GFRP and SSWM materails are carried out. An experiment investigation is conducted on RC beams strengthened using GFRPSSWM wrapping. Total twenty beam specimens are cast and subsequently are strengthened using GFRP-SSWM. Four are strengthened in flexure, four beams are strengthened in shear, and four beams are strengthened in flexure + shear. Size of all beam is kept 150mm x 200mm x 1800 mm. Beams are designed using IS code provisions.The beams are made different for flexure by reducing percentage of tensile reinforcement ,shear by increasing spacing of striupps, and for flexure + shear by reducing percentage of tensile reinforcement and by increasing spacing of striupps respectively. Variables considered in flexure ,shear and flexure + shear strengthening of beams are changing in orientation. The RC beams are subjected to two point loading during testing. xii Deflection at an interval of load, load at firrst crack, deflection at firrst crack, ultimate load, ultimate deflection and failure pattern are measured comparison is made between strengthened RC beam and controlled beam. Based on investigation presented in this project , it is observed that RC beam wrapped with different configuration by GFRP-SSWM wrapping exhibited significant increase in cracking and ultimate strength as compare to control specimen.