Cost estimation, optimization and competitiveness of different composite floor systems - Part 2: Optimization based competitiveness between the composite I beams, channel-section and hollow-section trusses

摘要

Part 2 presents the cost optimization, comparison and competitiveness between three different composite floor systems: composite beams produced from duo-symmetrical welded I sections, composite trusses formed from rolled channel sections and composite trusses made from cold formed hollow sections. In order to carry out a precise comparison between the mentioned composite systems, we applied the structural optimization method rather than classical structural analysis. The optimization was performed by the non-linear programming approach, NLP. The parametric optimization was made for simply supported beams of different spans, loads, steel costs (prices) and different hourly labour costs. An accurate cost objective function of the self-manufacturing material, power and labour costs, described in Part 1. were defined for the optimization and subjected to the design, stress and deflection (in)equality constraints in order to satisfy the requirements of both the ultimate and the serviceability limit state. The composite structures were designed in accordance with Eurocode 4. The aim of the comparison was lo define the spans and loads, at which each of the presented composite structures shows its advantages. Comparative diagrams, displayed at the end of the paper, can be usefully applied for choosing the optimal type of structure.