Fatigue strength of fibre-reinforced-polymer-repaired beams subjected to mild corrosion

2007 ◽  
Vol 34 (3) ◽  
pp. 414-421 ◽  
Author(s):  
Khaled A Soudki ◽  
Ahmad A Rteil ◽  
Rania Al-Hammoud ◽  
Timothy H Topper
Keyword(s):  
Fatigue Strength ◽  
Mass Loss ◽  
Fatigue Behaviour ◽  
Concrete Cover ◽  
Load Range ◽  
Cross Sectional ◽  
Rc Structures ◽  
Reinforced Polymer ◽  
Theoretical Mass ◽  
Fibre Reinforced Polymer

Infrastructure corrosion is an expensive problem worldwide. In the case of reinforced concrete (RC) structures, corrosion reduces the steel cross sectional area and thus decreases the capacity of the corroded RC members. The expansion of the corroded steel also induces tensile stresses in the concrete causing the concrete cover to crack and spall, thus reducing the bond capacity between concrete and steel. This paper reports on a research program conducted at the University of Waterloo that studied the effect of corrosion on flexural and bond fatigue strength. The effect of the addition of fibre-reinforced-polymer (FRP) sheets on the fatigue life of corroded RC beams was also assessed. Eighteen beams (152 mm × 254 mm × 2000 mm) were tested in two groups, with each group consisting of three sets of tests. Group F was designed to study the fatigue flexural behaviour; the repaired beams in this group were strengthened with a flexural FRP sheet along their tension side and confined by intermittent U-shaped FRP sheets along their length. Group B was designed to study the fatigue bond behaviour; hence, the repaired beams in this group were confined with U-shaped FRP sheets in the anchorage zone. The variables in each group were the percentage of corrosion (0% and 5% theoretical mass loss), the load range, and the use or omission of a FRP repair method. Results showed that a mild level of corrosion (5% theoretical mass loss) caused on average 10% and 20% reductions in flexural and bond fatigue strength, respectively. Strengthening the corroded beams with FRP sheets enhanced the fatigue behaviour of the beams. In both groups, the fatigue strength was on average 15% higher than that of the corroded unrepaired beams.Key words:corrosion, fibre-reinforced-polymer (FRP) sheets, fatigue strength, steel–concrete bond, flexural performance, durability.

Durability of coral-reef-sand concrete beams reinforced with basalt fibre-reinforced polymer bars in seawater

2021 ◽  
pp. 136943322098166
Author(s):  
Wang Xin ◽  
Shi Jianzhe ◽  
Ding Lining ◽  
Jin Yundong ◽  
Wu Zhishen
Keyword(s):  
Coral Reef ◽  
Marine Environment ◽  
Failure Modes ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Initial Stiffness ◽  
Basalt Fibre ◽  
Rc Structures ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

A combination of coral reef sand (CRS) concrete and fibre-reinforced polymer (FRP) bars provides an effective solution to the durability deficiency in conventional RC structures. This study experimentally investigates the durability of CRS concrete beams reinforced with basalt FRP (BFRP) bars in a simulated marine environment. Flexural tests are conducted on a total of fourteen CRS concrete beams aged in a cyclic wet-dry saline solution at temperatures of 25, 40 and 55°C. The variables comprise the types of reinforcement (steel and BFRP), the aging duration and the temperature. The failure modes, capacities, deflections and crack development of the beams are analysed and discussed. The results indicate that the ultimate load of the beams exhibits no degradation after aging, whereas the failure mode of the BFRP-CRS concrete beams transition from flexure to shear, which is caused by the degradation in the mechanical properties of the stirrups. The aged BFRP-CRS concrete beams show a substantial increase of over 70% in their initial stiffness compared with the control beams (beams without aging) and a substantial decrease in their crack width after aging due to the prolonged maturation of the concrete. Furthermore, a formula for calculating the shear capacity in the existing code is modified by a partial factor equal to 2, which can predict the capacity of a CRS concrete beam reinforced with BFRP bars in a marine environment.

scholarly journals Method for the Microstructural Characterisation of Unidirectional Composite Tapes

2021 ◽  
Vol 5 (10) ◽  
pp. 275
Author(s):  
Nico Katuin ◽  
Daniël M. J. Peeters ◽  
Clemens A. Dransfeld
Keyword(s):  
Voronoi Tessellation ◽  
Unidirectional Composite ◽  
Fibre Volume ◽  
Cross Sectional ◽  
Reinforced Polymer ◽  
Novel Approach ◽  
The Matrix ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Microstructural Characterisation

The outstanding properties of carbon fibre-reinforced polymer composites are affected by the development of its microstructure during processing. This work presents a novel approach to identify microstructural features both along the tape thickness and through the thickness. Voronoi tessellation-based evaluation of the fibre volume content on cross-sectional micrographs, with consideration of the matrix boundary, is performed. The method is shown to be robust and is suitable to be automated. It has the potential to discriminate specific microstructural features and to relate them to processing behaviour removing the need for manufacturing trials.

Fibre Reinforced Polymer Rebar

2015 ◽  
Vol 1124 ◽  
pp. 89-96
Author(s):  
Jan Prokeš
Keyword(s):  
Heat Transfer ◽  
Composite Materials ◽  
Concrete Cover ◽  
Fire Tests ◽  
Corrosion Attack ◽  
Advanced Composite ◽  
Reinforced Polymer ◽  
Advanced Composite Materials ◽  
Fibre Reinforced Polymer

The paper is focused on the use of advanced composite materials in the real application areas of buildings exposed to extreme environmental stress. The paper describe properties of composite rebar, especially with regards to long-term resistance to chemical and corrosion attack, minimization of heat transfer or resistance in construction with reduced concrete cover. The paper also presents behavior of composite rebar and concrete samples with composite reinforcement during loading and fire tests.

Concrete flexural members reinforced with fiber reinforced polymer: design for cracking and deformability

2002 ◽  
Vol 29 (1) ◽  
pp. 125-134 ◽  
Author(s):  
John Newhook ◽  
Amin Ghali ◽  
Gamil Tadros
Keyword(s):  
Cross Sectional Area ◽  
Fiber Reinforced Polymer ◽  
Sectional Area ◽  
Fiber Reinforced ◽  
Cross Sectional ◽  
Flexural Members ◽  
Crack Control ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Frp Bars

Fiber reinforced polymer (FRP) bars have lower modulus of elasticity than steel bars. For this reason when FRP bars are used as flexural nonprestressed reinforcement in concrete sections, the stress in the FRP is limited to a relatively small fraction of its tensile strength. This limit, necessary to control width of cracks at service, governs design of the required cross-sectional area of the FRP. Parametric studies on rectangular and T-sections are presented to show that the design based on allowable strain in the FRP results in sections that exhibit large deformation before failure. The concept of deformability, given in the Canadian Highway Bridge Design Code, as a requirement in the design of sections is discussed and modifications suggested. Using the new definition, it is shown that when, in addition to the crack control requirement, an upper limit is imposed on the cross-sectional area of the FRP, no calculations will be necessary to check the deformability.Key words: fibre reinforced polymer, reinforcement, concrete, design, deformability.

Fatigue behaviour of cracked steel beams retrofitted with carbon fibre–reinforced polymer laminates

2017 ◽  
Vol 21 (8) ◽  
pp. 1148-1161 ◽  
Author(s):  
Qian-Qian Yu ◽  
Yu-Fei Wu
Keyword(s):  
Carbon Fibre ◽  
Fatigue Behaviour ◽  
Interfacial Debonding ◽  
Experimental Program ◽  
Steel Beams ◽  
Special Focus ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Polymer Laminates

In recent years, externally bonded carbon fibre–reinforced polymer has been considered an innovative way to strengthen steel structures attributed to its high strength-to-weight ratio, excellent corrosion resistance and fatigue performance. This article presents an experimental and numerical study on the fatigue behaviour of defected steel beams strengthened with carbon fibre–reinforced polymer laminates, with a special focus on the effect of interfacial debonding. Analytical modelling and numerical simulation confirmed that the interfacial debonding had a pronounced effect on carbon fibre–reinforced polymer strain and stress intensity factor at the crack front. After introducing interfacial debonding from experimental findings into the numerical analysis, the fatigue life and crack propagation versus cycle numbers of the specimens compared well with the test results. Based on the current experimental program, specimens with Sikadur 30 were more prone to debonding failure; therefore, Araldite 420 is suggested for strengthening schemes.

scholarly journals Numerical Modeling of GFRP Reinforced Concrete Slabs

2017 ◽  
Vol 1 (4) ◽  
Author(s):  
Omer R EL Zaroug, John P Forth, Jianqiao YE
Keyword(s):  
Finite Element ◽  
Mechanical Load ◽  
Weight Ratio ◽  
High Strength ◽  
Load Range ◽  
Finite Element Program ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Element Program ◽  
Fibre Reinforced Polymer

The use of non-metallic fibre reinforced polymer reinforcement as an alternative to steel reinforcement in concrete is gaining acceptance mainly due to its high corrosion resistance. High strength-to-weight ratio, high stiffness-to-weight ratio and ease of handling and fabrication are added advantages. Other benefits are that they do not influence to magnetic fields and radio frequencies and they are thermally non-conductive. However, the stress-strain relationship for Glass fibre reinforced polymer reinforcement (GFRP) is linear up to rupture when the ultimate strength is reached. Unlike steel reinforcing bars, GFRP rebars do not undergo yield deformation or strain hardening before rupture. Also, GFRP reinforcement possesses a relatively low elastic modulus of elasticity compared with that of steel. As a consequence, for GFRP reinforced sections, larger deflections and crack widths are expected than the ones obtained from equivalent steel reinforced sections for the same load. This investigation provides details of the numerical analysis of GFRP reinforced slabs loaded mechanically using the commercial finite element program (DIANA). To prove the validity of the proposed finite element approach, a comparison is made with experimental test results obtained from full-size slabs. The comparisons are made on the basis of first cracking load, load-deflection response at midspan, cracking patterns, mode of failure and loads at failure. Using the DIANA software for the analysis of GFRP reinforced slabs under mechanical load is possible and can produce acceptable predictions throughout the load range in terms of final load and crack patterns. However, DIANA overestimated the first cracking load and tended to over predict the experimental deflections.  

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