الفهرس 
صفحة العنوانOnly 14 pages are availabe for public view
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Abstract
Columns are compression members which transmit loads from the top to the lower levels, and then to the soil through the foundations. Since columns are the most important elements of the structures, failure of one column in a critical location can cause a progressive collapse of adjoining floors and may reach to collapse of the entire structure. In this respect, the repair and strengthening of columns is a very important subject to reduce the building failure and to keep the columns capacity.
Fifteen typical scale reinforced concrete columns are constructed and confined with different types of strengthening. These techniques are Basalt fiber reinforced polymer, carbon fiber reinforced polymer and glass fiber reinforced polymer. The columns are tested under uniaxial compressive loads to study the effect of confinement on the structural behavior of circular R. C. columns. Test results for each column are presented in the form of crack patterns, load- strain curves and load- displacement curves.
Test results show that confining of the R. C. columns using different techniques of strengthening results in significant improvement of the general behavior of the columns. Wrapping using BFRP, CFRP & GFRP enhances ductility and ultimate strength as well.
All kinds of confinements enhanced the energy absorption capacity for columns comparing to that of the reference specimen. The highest values of energy absorption were in the case of strengthening by 2 layers of basalt fiber. Partial confinement using CFRP with one layer gives lower values but is better than basalt,the effect of whole height (CB1) and (CB4) was almost the same. The same trend of results was obtained in the case of the measure of ductility.
The results revealed that the laboratory results are higher than the theoretical results and therefore:
To obtain very good results with a good agreement with the theoretical results of the strengthening of basalt, carbon and glass fibers of the same equation by multiplying by the coefficient k and using the modified equation (5-6), where k is the strength enhancement factor.
• To strengthen the basalt, carbon and glass fiber, it is clear that the Egyptian code equation is very accurate by adjusting the value of k:
K = (1.1 → 1.6) for basalt fiber
K = (1.5 → 1.6) for carbon fiber
K = (1.3 → 1.5) for glass fiber
Increasing the basalt fiber layers by the whole column or using slices gives the required values for confinement but if using one layer does not produce the desired results.