Comparative assessment of buildings with pure steel or steel-concrete composite columns using structural design optimization

Abstract

The present work investigates the cost-effectiveness of fully encased composite columns and concrete filled tubes as an alternative to pure steel I-shaped columns. In order to achieve objectiveness in the comparison of the three methods, the designs assessed are obtained by a structural optimization procedure. Thus, any subjectivity which would result from the designer's experience is avoided. The Evolution Strategies optimization algorithm is employed to minimize structural cost subject to constraints associated with: (a) Eurocode 4 provisions for safety of composite column-members, (b) Eurocode 3 provisions for safety of steel structural members and (c) structural system resistance. Furthermore, the assessment is performed for a variety of seismic intensities, as it provides important information on the ability of each method to meet high performance criteria and the total cost increase such requirements would lead to. The results obtained provide an insight to the advantages of partially substituting steel as a main structural material with concrete, in composite column sections, and demonstrate the effectiveness of the proposed optimization approach.