With the advancement technology for reinforced concrete structures, it becomes increasingly feasible to use this technology for steel structures. The objective of this work is to present the formulation of the optimization problem of steel beams with external pretension with straight or polygonal tracing cables, considering the environmental and economic impacts. For the objective function formulation, the minimization of CO2 emission and cost in the design of the structure was considered. As constraints were established the states limits imposed by ABNT NBR 8800:2008. The program was developed within the MATLAB Platform (2016) and the optimization problem solution was obtained through the native Genetic Algorithms method. Routine validation was performed using examples found in the literature and an analysis of the predominant collapse modes was performed. The results indicate that monosymmetric profiles have gains when it comes to reducing CO2 emissions and cost when compared to doubly symmetrical profiles, in addition it was observed that straight cables generate better values of CO2 emission and cost when compared to polygonal cables.

With the advancement technology for reinforced concrete structures, it becomes increasingly feasible to use this technology for steel structures. The objective of this work is to present the formulation of the optimization problem of steel beams with external pretension with straight or polygonal tracing cables, considering the environmental and economic impacts. For the objective function formulation, the minimization of CO2 emission and cost in the design of the structure was considered. As constraints were established the states limits imposed by ABNT NBR 8800:2008. The program was developed within the MATLAB Platform (2016) and the optimization problem solution was obtained through the native Genetic Algorithms method. Routine validation was performed using examples found in the literature and an analysis of the predominant collapse modes was performed. The results indicate that monosymmetric profiles have gains when it comes to reducing CO2 emissions and cost when compared to doubly symmetrical profiles, in addition it was observed that straight cables generate better values of CO2 emission and cost when compared to polygonal cables.