Strengthening of reinforced concrete columns with various methods

Date
2003
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Abstract
As our infrastructure ages, many structures need strengthening to cope with increases in permitted loads. One area of concern is the repair of concrete columns. Severe corrosion of the reinforcing steel and the trouble of total replacement requires a non-destructive, easily applied method of protection and strengthening be used. One such renovation method involves the use of Fibre Reinforced Polymers (FRP's). These lightweight, high strength materials could be a new strengthening option for the rehabilitation of civil engineering structures. In an initial series of tests, square concrete columns were strengthened by wrapping with Carbon Fibre Reinforced Polymer (CFRP) sheets. The strength gains were higher than predicted. The inaccuracy of the predictions and the expense of the methodology used, indicated that further tests were required. These results suggested that column strengthening in not well understood, nor are there well-defined types of strengthening measures to suit different circumstances. More economical measures are desired in addition to strength prediction. Current design methods are based on the ultimate strain capacity of the wrap however, because of vertical compression cracks in the column, and/or buckling failure of the steel reinforcement the column fails prematurely. The results from the initial tests lead to the strengthening of fifty-four circular columns with six different strengthening measures. The measures that were assessed are: CFRP wrap, Glass FRP wrap (GFRP), GFRP spray, Steel hose clamps and column enlargement with additional concrete. For each measure, the Cost/Benefit ratio was determined accounting for the strength increase and initial costs. From the testing two things were observed 1) the strengthening measure with the best benefit/cost was sprayed GFRP and 2) Localized strain failure of the FRP jacket occurs because of circumferential column expansion at vertical compression cracks.
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Bibliography: p. 112-115
Some pages are in colour.
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Citation
Scholefield, B. W. (2003). Strengthening of reinforced concrete columns with various methods (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/70
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