Optimal design of a reinforced concrete frame

Abstract

The optimal design of a reinforced concrete frame is dealt with by decomposition of the problem into a series of sub-frames with prismatic beams, columns and slabs. The optimization criterion chosen is the total cost of construction. An algorithm was developed to optimize the said problem and generate results for several different optimized subframes. The implementation of the algorithm in a computerized program is discussed in detail along with the parameters required to perform the necessary calculations. The optimization of a single sub-frame using the developed algorithm took under 3 seconds on a typical workstation. An analysis of the results produced shows that the columns and slabs can be optimized independently of the sub-frame. The optimal beam width is also found to be, generally, the minimum practical dimension possible while satisfying steel reinforcement spacing requirements. It is also shown that, for a fixed total span to be covered, a smaller number of spans is more economical. At current local market prices, using a lower concrete grade will generally result in a lower overall price and the optimization process can give savings of about 50%. A sensitivity analysis of the problem is also presented.