Effect of Confinement on Strength Concrete Columns of Reinforced

Abstract

The objective of this study is to investigate the effect of confinement on the strength of concrete columns subjected to eccentric load when using different spacing of tied reinforcement. A total number of 48 reinforced concrete columns was tested.Each column has a cross sectional area of 20x30 cm with a height of 120 cm and is reinforced with 6 main bars with a diameter of 12 mm. The samples of columns were divided into 4 groups and each group had 12 columns. The first group was the columns without any confinement, the rests were the columns with confinement provided by tied bars having a diameter of 6 mm. The second, third, and fourth groups were the columns with a spacing of tied bars of 5 cm, 10 cm, and 20 cm, respectively. Each group was tested in 4 cases, having load eccentricity of 0, 3, 6, and 9 cm, respectively,from the centroid of the column. Three columns were tested for each case.

The results showed that the columns with tied bar resisted higher load than the one without any tied bar. It was found that the columns with heavy confinement gave higher compressive loads and larger lateral deflections as compared with the columns of less confinement. For columns without any confinement, the failure occurred suddenly when the columns reached their ultimate loads. In contrary to the columns with confinement, cracks were observed at the covering of the columns,then spalling occured, after that the columns failed slowly.