Shear Strengthening of Reinforced Concrete Deep Beams with Openings Using Glass Fiber Reinforced Polymer (GFRP) Composites
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Date
2020-03
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Addis Ababa University
Abstract
Reinforced concrete deep beams are structural elements loaded as simple beams in which
large amount of the load is transferred to the supports by a compression force connecting
the load and the reaction. These beams are widely used as transfer girders, foundation
walls, walls of bunkers and load bearing walls. Utility pipes and ducts are necessary to
accommodate electrical and mechanical services including air conditioning, power
supplies, telephone cables, computer accessories, sewerage lines and water supply. The
provision of opening holes in the web of a reinforced concrete deep beams causes many
problems in the beam behavior such as reduction in the beam stiffness, excessive
cracking, excessive deflection and reduction in the beam strength. Enlargement of such
openings due to electrical or mechanical requirements would reduce the element‟s shear
capacity. When such enlargement is unavoidable, adequate measures should be taken to
strengthen the beam and counteract the strength reduction. In this study an experimental
investigation on the strengthening of reinforced concrete deep beams with circular and
square openings is conducted. A total of nine specimens with circular and square
openings are constructed and tested under point loading. The test specimen has a cross
section of 100 x 500mm and a total length of 1050mm. Two circular or square openings,
one in each shear span, are placed symmetrically about the mid-point of the beam.
Externally bended glass fiber reinforced polymer (GFRP) shear strengthening on the
beam was found very effective in upgrading the shear strength of the reinforced concrete
deep beams. It was found that externally bonded GFRP is very effective to enhance the
shear strength of the RC deep beams. The strength gain caused by the application of
GFRP was in the range of 37% - 66% as compared to the load carrying capacity of unstrengthened
deep
beams.
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Keywords
deep beams, glass fiber reinforced polymer, strengthening