MINIMUM-COST DESIGN OF RC FRAMES USING THE DCOC METHOD .1. COLUMNS UNDER UNIAXIAL BENDING ACTIONS

The paper solves the minimum-cost design problem of RC plane frames. T he cost to be minimized includes those of concrete, reinforcing steel and formwork, whereas the design constraints include limits on maximum deflection at a specified node, on bending and shear strengths of bea ms and on combined axial and bending strength of columns, in accordanc e with the limit state design (LSD) requirements. The algorithms devel oped in this work can handle columns under uniaxial bending actions. I n the companion paper the numerical procedure is generalized to includ e columns subjected to biaxial bending. On the basis of discretized co ntinuum-type optimality criteria (DCOC), the design problem is systema tically formulated, followed by explicit mathematical derivation of op timality criteria upon which iterative procedures are developed for th e solution of design problems when the design variables are the cross- sectional parameters and steel ratios. For practical reasons, the cros s-sectional parameters are chosen to be either uniform per member or u niform for several members at a given floor level. The procedure is il lustrated on several test examples. It is shown that the DCOC-based me thods are particularly efficient for the design of large RC frames.