Interfacial debonding failure for reinforced concrete beams strengthened with carbon-fibre-reinforced polymer strips

2009 ◽  
Vol 36 (1) ◽  
pp. 103-121 ◽  
Author(s):  
Ryan Bakay ◽  
Ezzeldin Yazeed Sayed-Ahmed ◽  
Nigel Graham Shrive
Keyword(s):  
Reinforced Concrete ◽  
Interfacial Debonding ◽  
Design Methods ◽  
Reinforced Concrete Beams ◽  
Strain Compatibility ◽  
Reinforced Polymer ◽  
Experimental Programme ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Strengthening Technique

Rehabilitation of structures using fibre-reinforced polymers (FRPs) has become a preferred strengthening technique. Crack-induced debonding failure has been repeatedly recorded when using fibre-reinforced polymer (FRP) laminates to strengthen reinforced concrete (RC) beams and (or) slabs in flexure. A testing programme has been performed to determine the effect of the concrete compressive strength and the amount of shear reinforcement on the interfacial debonding. The ultimate strain at failure in the bonded laminates (usage efficiency) and the strain compatibility between the laminates and the concrete sections have been investigated. The current design methods for reinforced concrete members strengthened with FRP do not explicitly consider the interfacial debonding failure; using the results of the experimental programme, the applicability and limitations of these design methods are identified. New design procedures are proposed and compared with the experimental programme results and the currently adopted procedures.

Behaviour of reinforced GFRP bars concrete beams having strengthened splices using CFRP sheets

2021 ◽  
pp. 136943322110015
Author(s):  
Akram S. Mahmoud ◽  
Ziadoon M. Ali
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
New Method ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Strength Capacity ◽  
Cfrp Sheet ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

When glass fibre-reinforced polymer (GFRP) bar splices are used in reinforced concrete sections, they affect the structural performance in two different ways: through the stress concentration in the section, and through the configuration of the GFRP–concrete bond. This study experimentally investigated a new method for increasing the bond strength of a GFRP lap (two GFRP bars connected together) using a carbon fibre-reinforced polymer (CFRP) sheet coated in epoxy resin. A new splicing method was investigated to quantify the effect of the bar surface bond on the development length, with reinforced concrete beams cast with laps in the concrete reinforcing bars at a known bending span length. Specimens were tested in four-point flexure tests to assess the strength capacity and failure mode. The results were summarised and compared within a standard lap made according to the ACI 318 specifications. The new method for splicing was more efficient for GFRP splice laps than the standard lap method. It could also be used for head-to-head reinforcement bar splices with the appropriate CFRP lapping sheets.

Behaviour of reinforced concrete beams strengthened with carbon fibre reinforced polymer laminates subjected to corrosion damage

2000 ◽  
Vol 27 (5) ◽  
pp. 1005-1010 ◽  
Author(s):  
Khaled A Soudki ◽  
Ted G Sherwood
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Concrete Beams ◽  
Corrosion Damage ◽  
Corrosion Process ◽  
Reinforced Concrete Beams ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

The viability of carbon fibre reinforced polymer (CFRP) laminates for the strengthening of corrosion damaged reinforced concrete bridge girders is addressed in this paper. Ten reinforced concrete beams (100 × 150 × 1200 mm) with variable chloride levels (0-3%) were constructed. Six beams were strengthened by externally epoxy bonding CFRP laminates to the concrete surface. The tensile reinforcements of three unstrengthened and four strengthened specimens were subjected to accelerated corrosion by means of impressed current to 5, 10, and 15% mass loss. Strain gauges were placed on the CFRP laminates to monitor and quantify tensile strains induced by the corrosion process. Following the corrosion phase, the specimens were tested in flexure in a four-point bending regime. Test results revealed that CFRP laminates successfully confined the corrosion cracking, and the total expansion of the laminate exhibited an exponential increase throughout the corrosion process. All the strengthened beams exhibited increased stiffness over the unstrengthened specimens and marked increases in the yield and ultimate strength. The CFRP strengthening scheme was able to restore the capacity of corrosion damaged concrete beams up to 15% mass loss.Key words: CFRP laminates, corrosion, confinement, expansion, load tests, strengthening, bond strength, reinforced concrete.

scholarly journals Behaviour of Reinforced Concrete Beams Bonded with Glass Fibre Reinforced Polymer and Carbon Fibre Reinforced Polymer Sheets

2020 ◽  
Vol 9 (3) ◽  
pp. 134-138
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Externally Bonded ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

Concrete, a mixture of different aggregates bonded with cement, first developed around 150BC in Rome has been bedrock to the modern Infrastructure. It is used to build everything from roads, bridges, dams to sky scrapers. Strengthening concrete is traditionally done by using steels but the developments in technology in recent decades allowed to use fiber reinforced plastics which are externally bonded to concrete . Such composite materials offer high strength, low weight, corrosion resistance, high fatigue resistance, easy and rapid installation and minimal change in structural geometry. This study investigates the behavior of reinforced concrete beams bonded with fiber composites. A numerical study is conducted to study the behavior of RC beam under Static third point loading. Concrete beam specimens with dimensions of 150 mm width, 300 mm height, and 2600 mm length are modelled. These beams are externally bonded with Glass Fiber Reinforced Polymer (GFRP) sheets and Carbon Fibre Reinforced Polymer (CFRP) sheets. In present study, we examine the performance of reinforced concrete beams which are bonded with GFRP and CFRP sheets with various thicknesses (1, 2 & 3 mm) using ABAQUS in terms of failure modes, enhancement of load capacity, load-deflection analysis and flexural behaviour

Review of shear design methods for reinforced concrete beams strengthened with fibre reinforced polymer sheets

2001 ◽  
Vol 28 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Christophe Deniaud ◽  
JJ Roger Cheng
Keyword(s):  
Reinforced Concrete ◽  
Glass Fibre ◽  
Mechanical Model ◽  
Concrete Beams ◽  
Design Methods ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Shear Design ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper reviews the different shear design methods found in the literature for reinforced concrete beams strengthened externally with fibre reinforced polymer (FRP) sheets and compares the adequacy of each method by using the test results from the University of Alberta. The FRP shear design methods presented include the effective FRP strain and the bond mechanism criteria, the strut-and-tie model, the modified compression field theory, and a mechanical model based on the strip method with shear friction approach. Sixteen full-scale T-beam test results were used in the evaluation. Two web heights of 250 and 450 mm and two ready mix concrete batches of 29 and 44 MPa were used in the test specimens. Closed stirrups were used with three spacings: 200 mm, 400 mm, and no stirrups. Three types of FRP were used to strengthen externally the web of the T-beams: (i) uniaxial glass fibre, (ii) triaxial (0/60/–60) glass fibre, and (iii) uniaxial carbon fibre. The results showed that the mechanical model using the strip method with shear friction approach evaluates better the FRP shear contribution. The predicted capacities from this mechanical model are also found conservative and in excellent agreement with the test results.Key words: beams, carbon fibres, composite materials, fibre reinforced polymers, glass fibres, rehabilitation, reinforced concrete, shear strength, sheets, tests.

scholarly journals DESIGN OF FRP REINFORCED CONCRETE BEAMS FOR SERVICEABILITY REQUIREMENTS

2012 ◽  
Vol 18 (6) ◽  
pp. 843-857 ◽  
Author(s):  
Cristina Barris ◽  
Lluís Torres ◽  
Cristina Miàs ◽  
Irene Vilanova
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Elastic Behaviour ◽  
Rc Beam ◽  
Limit States ◽  
Strain Compatibility ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Linear Elastic Behaviour

Serviceability Limit States (SLS) may govern the design of concrete elements internally reinforced with Fibre Reinforced Polymer (FRP) bars because of the mechanical properties of FRP materials. This paper investigates the design of Fibre Reinforced Polymer reinforced concrete (FRP RC) beams under the SLS of cracking, stresses in materials, and deflections. A formulation to calculate the bending condition at which crack width and stresses in materials requirements are fulfilled is presented based on principles of equilibrium, strain compatibility and linear elastic behaviour of materials. The slenderness limits to comply with the deflection limitation are redefined and a methodology to calculate the optimal height of an FRP RC beam to satisfy all of these serviceability requirements is proposed. This procedure allows optimising the dimensions of an FRP RC beam taking into account the specific characteristics of the element, such as the mechanical properties of materials and the geometric and loading conditions.

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