Tall, rigidly jointed frames cun dejlect excessively to tile extent that the sway deflection of the members governs the choice of their sections. In this paper a simple method is proposed for the design of reinforced concrete frames so that the serviceability, as well as the ultimate limit state, requirements are both satisfied. Design equations are proposed that are iteratively select the cross-sectional properties of the columns, in such a way that the sway limit state is satisfied in the most economic manner. These sections are then checked for the ultimate limit state and, if necessary, member sizes and reinforcements are altered so that the strength of the framee is also adequate. The method avoids the repeated solution of the stiffness equations simultaneously and thus saves both computer time and storage. The paper also gives the steps for a quick design of columns subject to given bending momentss and axial louds using CP110. The design of a tall 24-storey unsymmetrical frame is given as an example to demonstrate that the serviceability limit state can decide the sectional dimensions and their reinforcements.
Peofessor K.I. Majid and S. Okdeh