Performance based design optimization of steel concentric braced structures

According to the recent tendencies in the seismic engineering, the structures are designed to survive the rare seismic events without local and global collapse and for limited damages in case of frequent earthquakes. The Performance Based Design (PBD) provides an effective tool for the engineers to design well performing buildings related to several demands since nonlinear analysis has become daily routine. However, it may be difficult to find an optimal structural configuration and the design process can be extremely time-consuming due to complexity of the problem (e.g. large number of design variables, nonlinear structural response, energy dissipation through plastic mechanisms and nonlinearity in demands). Structural optimization in these cases can be an effective alternative to determine cost effective and well performing solutions. This consideration motivated the study presented in this paper, where an advanced complex structural optimization process is discussed. The proposed methodology is able to find optimal structural solutions accounting for both the structural performance at different seismic intensity levels and the relevant risks and constructional costs. In order to show the efficiency and the potentiality of this approach, the methodology and the developed algorithm have been illustrated through numerical example of optimization of Concentric Braced Frame (CBF) structures.