A rapid method for assessing the ultimate strength of reinforced concrete members subjected to axial compression and biaxial bending is presented. The design procedure is computerised to full automation for arbitrary cross-sections, with or without voids. The concept of load fraction, which is the fraction of the applied load that can be adequately withstood, is introduced for quantitative measure of structural adequacy. The load fraction also provides useful guidelines to necessary redesign. An iterative procedure is evolved for making adequate provision for ultimate strength by gradually increasing the amount of rein forcement till the required load fraction is achieved. Reinforcement is always added at locations having the highest increase of load fraction/unit area of added reinforcement. Practical considerations in symmetry, nominal rein forcement, and steel congestion, etc., are taken into account.
K.H. Kwan and T.C. Liauw