Stochastic Multi-objective Optimisation of Exoskeleton Structures
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Stochastic Multi-objective Optimisation of Exoskeleton Structures Anna Reggio1 · Rita Greco2 · Giuseppe Carlo Marano1 · Giuseppe Andrea Ferro1 Received: 31 March 2020 / Accepted: 29 October 2020 / Published online: 18 November 2020 © The Author(s) 2020
Abstract In this study, a structural optimisation problem, addressed through a stochastic multiobjective approach, is formulated and solved. The problem deals with the optimal design of exoskeleton structures, conceived as vibration control systems under seismic loading. The exoskeleton structure is assumed to be coupled to an existing primary inner structure for seismic retrofit: the aim is to limit the dynamic response of the primary structure to prevent structural damage. A non-stationary filtered Gaussian white noise stochastic process is taken as the seismic input. Design variables pertain to the mechanical properties (stiffness, damping) of the exoskeleton structure. Two concurrent and competing objective functions are introduced, in order to take into account not only safety performance but also economic cost considerations. The resulting trade-off is solved searching the Pareto front by way of a controlled elitist genetic algorithm, derived from the Non-dominated Sorting Genetic Algorithm-II. Sensitivities of Pareto fronts and Pareto optimal sets to different system parameters are finally investigated by way of a numerical application. Keywords Multi-objective optimisation · Genetic algorithm · Structural optimisation · Random vibration · Vibration control
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Anna Reggio [email protected] Rita Greco [email protected] Giuseppe Carlo Marano [email protected] Giuseppe Andrea Ferro [email protected]
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Department of Structural, Geotechnical and Building Engineering, Politecnico di Torino, Turin, Italy
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Department of Civil, Environmental, Territory, Building and Chemical Engineering, Politecnico di Bari, Bari, Italy
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Journal of Optimization Theory and Applications (2020) 187:822–841
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1 Introduction Engineering structures undergo environmental loads, both natural (seismic action, wind pressure, sea waves, etc.) and anthropic (pedestrian-induced excitation, road and railway traffic, etc.) that are dynamic in time and intrinsically stochastic in nature. When the resulting structural vibration could reach levels impairing serviceability and safety performance, it can be significantly reduced by way of vibration control technologies [1–4]. In earthquake-prone regions, to improve the resilience of the built environment [5], vibration control technologies can be successfully applied to the seismic retrofitting of existing structures. To this end, one of the most promising strategies is currently given by exoskeleton structures. We define an exoskeleton structure as a self-supporting structural system set outside and suitably connected to a primary inner structure, the latter being enhanced or protected, in a general sense, by virtue of this connection. Impressive real applications of exoskeleton structures to building refurbishment projects al
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