Intervention cost optimization of bracing systems with multiperformance criteria

In this paper a multiperformance optimization procedure to design dissipative bracing systems controlling the structural performance while minimizing the intervention cost is proposed. The procedure allows dimensional and topological optimization of bracing, considering inelastic behaviour of braced structures through properly developed visco-elastic equivalent linearization schemes. The structural behaviour is controlled through constraint functions on interstory drift ratio (IDR) while the intervention cost is explicitly encountered by considering real costs that mainly influence it. The procedure is suitable for both new and existing structures, however the objective function is specialized on typical costs of retrofit interventions. A numerical example on a multistory frame has been developed in order to show the effectiveness of the procedure to provide the optimal characteristics and arrangement for the braces, while the suitability of linear equivalent schemes to predict the structural response is investigated through Nonlinear dynamic analyses. Further, a comparison of the estimated intervention costs by asking for different performance levels is performed, showing how the proposed objective function is able to help the designers to identify the ideal performance levels and acceptance criteria to reduce the cost-benefit ratio.