Behavior of reinforced concrete beams strengthened with CFRP rod panels CRP 195. (November 2018)

• Record Type: Journal Article
• Authors: Jawdhari, Akram; Harik, Issam; Fam, Amir
• Is Part Of: Structures. Volume 16(2018)
• Page Start: 239
• Page End: 253
• Publication Date: 2018-11
• Subjects: τa Interfacial shear stress between CRP and concrete -- εf axial strain in CRP -- Ef tensile modulus of elasticity of CFRP rods -- Af total area of CFRP rods in CRP -- wf width of CRP -- ρf CRP reinforcement ratio -- fc compressive stress in concrete -- εc strain in concrete -- fc' compressive strength of concrete -- ε0 strain in concrete at fc′ -- εu ultimate strain in concrete -- Ec modulus of elasticity of concrete -- fy yield strength of steel reinforcement -- εy yield strain of steel reinforcement -- Es modulus of elasticity of steel reinforcement -- fuf rupture strength of CFRP rods -- εuf rupture strain of CFRP rods -- εfd debonding strain of externally bonded fRP reinforcement -- b width of the beam -- h height of the beam -- As tensile streel reinforcement area -- As' compressive streel reinforcement area -- d distance from top face to the centroid of tension steel reinforcement -- d' distance from top face to the centroid of compression steel reinforcement -- c depth of neutral axis from top face -- x depth of tensile concrete block from neutral axis -- ft tensile strength of concrete -- εt cracking strain of concrete -- Cc compressive force in concrete block -- Cs compressive force in steel reinforcement -- Tc tensile force in concrete -- Ts tensile force in steel reinforcement -- Tf tensile force in CRP -- Pmax maximum (ultimate) load of CRP strengthened beam -- Itr, cr transformed cracked moment of inertia of the beam -- nf modular ratio of elasticity between CRP and concrete -- df distance from top face to centroid of CFRP rods -- h' clear depth of concrete cover -- x0 distance from support to end of CRP -- Mdb, f beam's flexural debonding moment -- Vdb, s concrete shear capacity; Reinforced concrete -- Strengthening -- CFRP rod panels (CRPs) -- Cover separation -- Debonding; Structural engineering -- Periodicals; 624.1
• DOI: 10.1016/j.istruc.2018.09.014
• Languages: English
• ISSNs: 2352-0124

Abstract

Abstract: This paper investigates the behavior of reinforced concrete beams strengthened in flexure using externally bonded carbon fiber reinforced polymer (CFRP) rod panels (CRPs) fabricated using 4 mm rods spaced at 9.5 mm. The experimental program consisted of a control beam and three beams strengthened with either a continuous CRP, a spliced CRP with two half-length CRPs spliced through a 150 mm finger joint, or a spliced and end-anchored CRP. Spliced panel performed similar to the continuous one, with no debonding observed at finger joint. They resulted in a comparable strength increase relative to the non-strengthened control beam of 95 and 104%, respectively, and failed by concrete cover separation (CCS) at CRP end. When the spliced CRP was end-anchored, the increase in strength was 195% relative to the control beam, with the finger-joint still intact, and the failure mode changed to intermediate crack-induced debonding (ICID). The analytical model, developed from sectional analysis and strength models for debonding failures, is capable of predicting the load-deflection response and ultimate loads, including the two observed debonding failures. For CCS failure, two models are presented, one is based on the concrete tooth model, and the other on the shear capacity model. The ICID failure was based on limiting the CFRP strain in accordance with ACI 440.2R-17 design guide. Results showed a good correlation between analytical predictions and test data.