الفهرس 
Deterioration of concreteOnly 14 pages are availabe for public view
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Abstract
The behavior of fourteen reinforced concrete column specimens with a variable aspect ratios of “1,2,and 3”, were tested to failure to examine the proposed techniques of CFRP strengthening in reinforced concrete rectangular columns. The deformation characteristics, including strains in the external fiber reinforcement system, ultimate load, and failure characteristics of the columns, were closely monitored; the effect of the aspect ratio and strengthening techniques.Strengthening of RC rectangular columns using CFRP sheet wrapping as external confinement can increase its loading carrying capacity depending on the column’s aspect ratio. It was confirmed that that the confinement efficiency has an inverted relation with the increase in the aspect ratio, moreover the confinement of was almost negligible for aspect ratio more than 2.For rectangular columns with aspect ratio more than 2 the confinement efficiency can be increased using the proposed techniques which used intermediate supports (rivets/ties). The strengthening techniques are mainly divided into two main categories; the full penetration of the cross section (ties), and the partial penetration of the cross section (rivets). The ties are made from, two materials were used the steel, and the CFRP, and as the ties are exactly the same but with Different cross-sectional area; for the sack of confinement enhancement it was confirmed that the rivets penetration depth is more effective than it’s cross sectional area.duplication of CFRP Cross sectional area gave an increase of 24% instead of 21% for the normal increase without duplication. However the duplication of the CFRP gave an increase almost as the increase in the CFRP tie which was 28% which is almost as high as the steel tie which was 30% increase.