International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 7, Issue 1, pp: (111-118), Month: April 2019 - September 2019, Available at: www.researchpublish.com
EXPERIMENTAL STUDY OF CORBEL BY STRENGTHENING WITH CFRP P.A.RANDHAVANE1, V.R.Rathi2, P.K.Kolase3 1
Post graduate student, Department of Civil Engineering, Pravara Rural Engineering College Loni, India-413736 2
Professor, Department of Civil Engineering, Pravara Rural Engineering College Loni, India-413736
3
Professor, Department of Civil Engineering, Pravara Rural Engineering College Loni, India-413736 Email-praju14257@gmail.com.
Abstract: The study represents the local behaviour of strengthened reinforced concrete short corbel by external bonding of Carbon Fibers Reinforced Polymer fabrics. For the experimental program total six corbels were casted with two control sample and four strengthened samples with externally CFRP Fabrics. Strut-n-tie method is used for the design of corbel, which is effective method for analyising forces in the corbel. Comparison for the ultimate load v/s deflection graphs were studied for the control and strengthened specimens. Test results showed improvement in the ultimate load carrying capacity for the strengthened samples with horizontal and inclined wrapping on the faces of the corbel. Full wrapping by the unidirectional CFRP Fabrics in the horizontal manner showed higher results compared with the control and inclined (45˚) orientation of CFRP Fabrics. Keywords: Corbel, Strut-n-tie, CFRP, Reinforced concrete, Strengthening, Failure.
1. INTRODUCTION Strengthening of reinforced concrete (RC) structures with Fiber-Reinforced Polymer (FRP) composites has been a .popular subject that attracted considerable attention and researchers for the last two decades. The high specific strength, stiffness, environmental resistance, and ease of application make FRP composites highly desirable for strengthening and rehabilitation of RC structural components [1] Corbels, or brackets, are cantilevers with a shear span depth ratio lower than unity, generally jutting out from walls or columns. They have the principal function of supporting prefabricated beams or floors at building joints, allowing, at the same time, the force transmission to the vertical structural members. [2] Bond between FRP and concrete is a fundamental property that influences the success and the efficiency of the strengthening system as it controls the composite action development between both material Besides, it affects the load carrying capacity, spacing and width of cracks, as well as the failure mode of the strengthened member [3]. According to Elgwady et al.[4], strengthening enhanced the ultimate load carrying capacity by values ranged from (8-30) %; the cracking loads of most strengthened specimens were about (70-80) % of their ultimate loads. A.A.Mohamad-Ali and Attiya [5] found that the external strengthening technique had a significant effect on the first cracking load, the percentage increase in cracking load for the inclined strips was 51%, and the percentage for the horizontal strips was 19%.. Heidayet et al. [5]investigated that the repair technique may be regarded as an effective and economical technique for strengthening existing structures. Engindeniz et al. [5]presented that externally bonded FRP composites can eliminate some important limitations of other strengthening methods such as difficulties in construction and increases in member sizes. Khalifa [5]proposed maximum vertical load carrying capacity applied on corbels was increased with the increasing of the fiber volume fraction, fiber aspect ratio and the increasing in concrete compressive strength. Yaman Sami Shareef Al-Kamaki et al.[6] Observed that CFRP reinforcement constrained widening and growth of the shear cracks, and hereafter, improved the gain in the load capacity and axial toughness. Karunasenaet al. [7] found that externally bonded composites, CFRP or GFRP, improved the moment capacity of damaged concrete beams. Varinder Singh et al. [7] CFRP retrofitting of the beam-column joint shifted the failure of the joint from the column portion to the beam portion of the joint which will prevent progressive collapse of the structure. S. J. E. Dias et al. [8] found that NSM CFRP laminates is an effective solution to decrease cracking, yielding and maximum loads of beams failing in bending. Furthermore, he
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