Optimization of reinforced concrete columns according to different environmental impact assessment parameters

In addition to economic gains, the use of optimization strategies in the development of a structural design can reduce the consumption of materials whose extraction, manufacture and transport cause large environmental damage, as occurs with reinforced concrete inputs. The aim of the present study was to optimize the monetary and environmental costs associated with pieces of rectangular reinforced concrete columns submitted to uniaxial bending and compression loads, using the harmony search algorithm, which consists of a meta-heuristic approach analogous to the process of attaining the best musical harmony. Therefore, in addition to taking into account the purchasing costs of materials in the structural optimization process, analyses were conducted to determine the environmental costs of each input, estimated from the life-cycle analysis. The sizes of concrete section and the amount and gauges of the structures, as well as concrete strength, were used as variables. The columns were checked as to ultimate and serviceability limit states following the ABNT NBR 6118/07 Brazilian standard. Several indicators were used for environmental cost minimization, and the results were compared to those obtained from conventional sizing processes as well as from other optimization methods. In general, even with structure optimization to minimize monetary costs, important reductions in environmental costs are obtained, regardless of the indicator used for impact analysis, thus yielding cross-sections with different features.