Synopsis
In this paper, expressions are developed which enable the designer to determine the load bearing capacity of concentrically loaded RC columns in a very simple manner. The 'reduction factor' (the ratio of the ultimate load of the column and that of the cross-section) is introduced. It is similar to that used for the calculation of steel, masonry and timber structures. The results are based on the second order analysis of RC columns taking also into account the effect of creep. The novelty of the paper is not the presented nonlinear solution of RC columns, rather the approximate 'back of the envelope' expressions, which are verified for the entire practical parameter range by a numerical solution.