Retrofitting of RC Beam using Glass Fiber Reinforced Polymer Composite
Abstract
Retrofitting is the modification of existing structure which may or may not be damaged to make them more resistant to external forces. The objectives like Upgraded loading requirements; damage by accidents and environmental conditions, rectification of initial design flaws, change of usage can be achieved by retrofitting. The solutions adopted are generally based on successful prior practice. It is necessary to take a decision whether to demolish a distressed structure or to restore the same for effective load carrying system. Many a times, the level of distress is such that with minimum restoration measures the structural component can be brought back to its normalcy and during such times retrofitting is preferred. One of the techniques of strengthening RC structural elements is through confinement with composite enclosure. FRP material, which are available in the form of sheet or laminates are used to enhance the flexural, shear, and axial load carrying capacity of these elements. The proposed technique consist of wrapping Glass Fiber Reinforced Polymer composite mats on the shear and Flexural zones of the RC beam and studying their characteristics
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Introduction
There is a pressing need to repair or upgrade the building and civil infrastructure in many parts of the world. For instance with the modernization of buildings, it is sometimes desirable to remove supporting walls or individual supports, leading to the need for local strengthening. The strengthening and enhancement of the performance of deficient structural elements or the structure as a whole is referred to as retrofitting. Retrofit aims to strengthen a building to satisfy the requirements of the current codes for seismic design. The building may not be damaged or deteriorated. The various retrofitting techniques include steel plate bonding, polymer injection followed by concrete jacketing, use of advanced composite materials like FRP, Ferro cement etc. Glass is the most common type of fiber used to reinforce composites. Glass-fiber-reinforced-plastics (GFRP) are commercially available at a fairly low cost. In general, the stress-strain relationship of GFRPs is linear to failure. The strength of certain types of GFRP exceeds that of the conventional steel, Moreover it is cost efficient .Therefore a detailed study is done on its properties by retrofitting beams.
Conclusion
A total of six beams were cast out of which two were controlled beams and two were retrofitted in the shear zone and the other two in the flexural zone after applying 75% of the Ultimate Load No horizontal cracks were observed at the level of the reinforcement, which indicated that there were no occurrences of bond failure. There was an increase of the shear load by 9%- 14% and an increase in the flexural load by 10%-14%.There is was considerable decrease in the stiffness of beam after retrofitting Due increased ductile nature