Life-cycle cost optimization of steel structures

This article addresses the life-cycle cost optimization of steel structures. The main factors in uencing the life-cycle cost of a structure are delineated and their e ects on various cost functions are discussed. A four-criteria optimization model is presented for the life-cycle cost optimization of steel structures. These criteria are (i) select discrete commercially available sections with the lowest cost, (ii) select commercially available sections with the lightest weight, (iii) select the minimum number of di erent types of commercially available sections, and (iv) select commercially available sections with the minimum total perimeter length. The last criterion models a representative type of cost incurred over the life of the structure, that is, preventative maintenance in the form of periodic painting of an exposed steel structure to avoid corrosion. The life-cycle cost optimization model is based on fuzzy logic with the goal of formalizing the life-cycle design process but with some input from the design engineer through introduction of weighting coe cients re ecting the relative importance of various criteria. The model is applied to a large steel structure with over 3300 members