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

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