Lightweight design optimization of a welded monorail track using an evolutionary algorithm

Abstract

This study presents the analysis and optimization of the mass of monorail track girders. Two types of girders were considered: a mono-symmetric welded I-profile and a double-symmetric I-profile variant. The objective function was the cross-sectional area of the I-profile, including weld areas. Constraints included the strength at critical points of the I-profile, weld strength, girder stiffness, and overall stability. The monorail track was analyzed in the span between two supports. An Evolutionary Algorithm, implemented in the Solver add-in of MS Excel, was used for optimization, allowing discrete design variables such as standard plate thicknesses and integer weld dimensions, thereby providing practical and implementable solutions. The proposed model was applied to real monorail tracks in operation that utilize standard I-profiles. The optimized solutions demonstrated material savings while satisfying all limit criteria, confirming the efficiency and applicability of the approach for practical design improvements in monorail track construction.