A robust computer procedure for weight minimisation of a high–rise and portal frames under the deflection constraint at various locations is presented. It replaces the conventional tedious and unreliable manual assessment for minimum weight design. Several practical considerations such as the Invariance or lower limit of wall thickness for fire resistance or building services requirements are Included in the optimisation procedure. The method is readily used in practical optimisation design of steel and reinforced concrete structures against the deflection limit. © 2003 Taylor & Francis Group, LLC.