Optimum design of a hybrid isolation device for server racks using constrained differential evolution algorithm

Nonstructural elements and contents often constitute a large fraction of the economic investment in ordinary buildings. In case of seismic events, damage to nonstructural elements not only contributes to the overall direct material costs but can also significantly impact the indirect costs. The latter are especially affected by earthquake-induced damage if production and business flows depend on proper functioning of such nonstructural components, since consequent downtime costs turn out to be very high. Within this framework, server racks' performance under seismic loading is of interest in the present work. The economic relevance of these nonstructural components requires the implementation of proper design solutions so that their performance under earthquakes can fulfill specific requirements. In this perspective, including isolation devices between server racks and building floors is deemed effective for enhancing the stability of the protected equipment, preserving the computer components' integrity and, minimizing downtime losses. Hence, the present work is meant to optimize a hybrid isolation system for server racks. Specifically, the hybrid isolation device designed for such application combines at least two elastomeric isolators and three sliders, and it is intended for the seismic protection of server racks characterized by different configurations. The objective function is formulated to minimize the accelerations transmitted to server racks and manufacturing cost.