Flexural strength enhancement of confined reinforced concrete columns

As part of a continuing research study, this paper proposes a new design ai d to calculate the actual moment capacity of confined reinforced concrete c olumns. Up to now the moment capacity of a reinforced concrete column is ca lculated based on the code's guidelines for an unconfined section. As most reinforced concrete columns contain transverse or confining reinforcement, which will enhance the column moment capacity, the actual moment capacity w ill be much higher than the unconfined moment capacity. This additional fle xural strength will increase the shear force demand in the column, and if i t is not accounted for in the design will jeopardise the column to fail in shear. In this study the actual moment capacity of a confined reinforced co ncrete column is obtained by multiplying the moment capacity calculated usi ng the BS 8110 method with the proposed flexural strength enhancement facto r. By using regression analysis, an equation for the flexural strength enha ncement factor is derived as the function of all the parameters that have e ffects on the moment capacity. An example is presented to show the accuracy of the proposed method.