31-10-2014, 02:15 PM
Abstracts: The strengthening or retrofitting of existing concrete structures to resist higher design loads, correct strength loss due to deterioration, correct design or construction deficiencies, or increase ductility has traditionally been accomplished using conventional materials and construction techniques. Composite materials made of fibers in a polymeric resin, also known as fiber-reinforced polymers (FRPs), have emerged as an alternative to traditional materials for repair and rehabilitation. There are many advantages of using fiber reinforced composites over the conventional methods and an attempt has been made to achieve a strength-cost optimisation between GFRP and CFRP through an experimental study. Total eight beams of length 2.1 m and cross sectional dimensions 150x300 mm are casted. All the specimens are identical. The beams are designed using IS: 456, 2000. This research work deals with the flexural strengthening of RCC beams with single layer GFRP, double layer GFRP and single layer CFRP. In India E-glass is widely used due to its less cost. CFRP which is the most efficient in strengthening is avoided as it is expensive. So this research work is an attempt study the behaviour of frp strengthened beams with more than one layer, and to study its advantages and drawbacks. This analysis among E-glass and CFRP fibers strengthened beams will be done by applying following wrap patterns on the casted beams. The wrapping is done on uncracked beams, considering the reason for strengthening as change in loading requirements. Out of 8 beams, Two are controlled beams, Two are wrapped on the flexural side with single layered GFRP,Two are wrapped on the flexural side with double layered GFRP and Two are wrapped on the flexural side with single layered CFRP.The testing of the beams is done under two point loading setup. Parameters that are observed include failure mode, cracking pattern, failure load, deflection under loads and mid span ,strain in concrete at neutral axis and axis parallel to tension and compression reinforcements respectively, increase in the moment carrying capacity of wrapped beams and a comparative study w.r.t cost and strength increased between beams wrapped with double layered GFRP and single layered CFRP wrap. The analytical results for moment carrying capacity are obtained byIS-456 and ACI 440 “Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures” for control bean and FRP strengthened beams respectively. The main objective was to find out how much does the strength increase with the use of double layered GFRP instead of single. Also what is the difference in the strength of double layered GFRP and single layered CFRP and is it beneficial to replace single layered CFRP by double layered GFRP.