Confinement of reinforced concrete columns with fibre-reinforced composite sheets - an experimental study

Demers, Marc; Neale, K.W.

doi:10.1139/l98-067

Cited by 159 publications

(50 citation statements)

References 8 publications

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“…[13] to allow for three areas of stress in the square columns and two in the circular column (unconfined (applicable to square columns only); confined due to the effect of the wrap, and confined due to both wrap and steel) would permit yet another estimate of column strength. Demers and Neale (1999) suggest, however, that additional confinement of concrete within the stirrups or spiral will only occur for "short" stirrup spacing.…”

Section: Discussionmentioning

confidence: 96%

Strengthening of concrete columns with carbon fibre reinforced polymer wrap

Shrive¹,

Azarnejad²,

Tadros³

et al. 2003

Can. J. Civ. Eng.

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Reinforced and prestressed concrete columns with one or two layers of carbon fibre reinforced polymer (CFRP) wrap were tested to failure in axial compression. When the results were compared with the maximum load predictions of two proposed design methods, the predictions consistently underestimated actual loads. The design methods are thus conservative. A simple analysis for circular columns reveals that the confining effect of the wrap is not engaged until the concrete actually starts failing and dilating. A finite element model of a chamfered square column confirms this analysis, as do strain readings from the tests. It is shown that strength gains are not linearly related to wrap thickness. The failure mechanism suggests that design should not be based on the ultimate strength or strain of the wrap and that strength gains can be expected to reduce with increasing brittleness of the concrete and with increasing eccentricity.

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Section: Discussionmentioning

confidence: 96%

Strengthening of concrete columns with carbon fibre reinforced polymer wrap

Shrive¹,

Azarnejad²,

Tadros³

et al. 2003

Can. J. Civ. Eng.

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“…The strength increase achieved by CFRP wrapping is expected to be greater for circular section columns than for square section columns. When a circular section column is wrapped, confining stresses are activated around the complete circumference, whereas for a square or rectangular section the confinement is effective only at the column corners, with negligible resistance to lateral expansion being provided along the flat column sides (Thériault and Neale 2000;Demers and Neale 1999). For the current tests the increased load-bearing area provided by the cylindrical concrete jacket will further increase the axial capacity of the columns.…”

Section: Carbon Fibre Reinforced Polymer Wrappingmentioning

confidence: 94%

“…Wrapping columns with CFRP is known to increase the strength of reinforced and prestressed concrete columns (Azarnejad et al 2000;Demers and Neale 1999), but similar test data for masonry columns are very limited (Micelli et al 2001). …”

Section: Introductionmentioning

confidence: 99%

Carbon fibre reinforced polymer wrapping for the rehabilitation of masonry columns

Masia¹,

Shrive²

2003

Can. J. Civ. Eng.

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The use of carbon fibre reinforced polymer (CFRP) wrapping to strengthen existing cracked masonry columns was investigated experimentally. The study was aimed at quantifying the increase in strength that can be achieved and assessing the effect of column size on the strength increase. Eighteen columns were tested, with three different square cross-sectional sizes (290 mm × 290 mm, 390 mm × 390 mm, 490 mm × 490 mm) and two different types of clay masonry unit. Six columns were constructed in each size, two columns using unit type 1 and four columns using unit type 2. Strengthening was achieved by wrapping the square section columns directly with a single-layer CFRP laminate or by wrapping the columns after first casting a circular concrete jacket around the column. The latter treatment was applied to two of the small-sized columns and two of the intermediate-sized columns. All other square section columns were wrapped directly. Significant strength increases were achieved, particularly when the columns were provided with the cylindrical concrete jacket. These preliminary tests indicate that the use of CFRP wrapping is an effective technique for rehabilitating damaged masonry columns. Decisive conclusions could not be made regarding the effect of column size (cross-sectional area) on the strength increase achieved. Further tests together with nonlinear finite element modelling aimed at duplicating the experimental observations would greatly enhance the information provided by the current tests.Résumé : L'utilisation de couches de polymères renforcés par fibres de carbone (« carbon fibre reinforced polymer : CFRP ») pour consolider des colonnes de maçonnerie fissurées a été étudiée au moyen d'expériences. Le but était de quantifier l'augmentation de résistance qui pouvait être atteinte et d'évaluer l'effet de la dimension des colonnes sur l'augmentation de la résistance. Dix-huit colonnes carrées (290 mm × 290 mm, 390 mm × 390 mm, 490 mm × 490 mm) ont été mises à l'épreuve; elles étaient composées d'éléments de deux types différents d'argile de maçon-nerie. Six colonnes de chaque dimension ont été construites, deux colonnes utilisant l'élément de type 1 et quatre l'élément de type 2. Le renforcement a été réalisé en enroulant les colonnes de section carrée d'une seule couche de laminé CFRP, ou en enrobant les colonnes après avoir préalablement coulé une gaine de béton circulaire autour de la colonne. Ce dernier traitement a été appliqué à deux colonnes de petites dimensions et à deux colonnes intermédiaires. Toutes les autres colonnes carrées ont été enrobées directement. Des augmentations importantes de résistance ont été atteintes, surtout avec la gaine de la gaine de béton circulaire. Ces essais préliminaires indiquent que l'utilisation d'une couche de CFRP représente une technique efficace pour restaurer les colonnes en maçonnerie endommagées. Des conclusions probantes n'ont pu être atteintes quant à l'effet de la dimension des colonnes (superficie de la section transversale) sur l'augmentation de la résistance ...

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“…Karbhari and Gao conducted a pilot study of CFRP/GFRP reinforced cylindrical concrete, with the number of layers of CFRP and the winding angle as variable parameters (Karbhari & Gao, 1997). Demers and Neale analysed the longitudinal reinforcement ratio, the stirrup reinforcement ratio, the degree of reinforcement corrosion and precrack state towards the performance of reinforced stuff, through testing of 16 full-size FRP confined reinforced concrete specimens (Demer & Neale, 1999). Hui analysed the FRP layers, reinforcement spacing, the affect of the mixed use of fibre and some other factors on the performance of reinforcement (Hui, 2003).…”

Section: Introductionmentioning

confidence: 99%