Design and assessment of steel and steel-concrete composite structures: efficacy of en1998 design procedure

Design codes for seismic constructions allow the realization of structures able to dissipate energy through cyclic plastic deformations localized in specific zones, selected to involve the largest number of structural elements. The capacity design approach requires an opportune selection of the design forces and an accurate definition of structural details in the plastic hinges. The structural elements in which plastic hinges are located are over-sized with respect to the seismic actions obtained by the use of the design spectrum, while the elements that shall remain elastic are over-sized with respect to dissipative elements. The capacity design methodology requires an accurate control of the localization of plastic hinges, strongly influenced by the actual mechanical properties of materials. In the present work, developed inside the research project OPUS, different case studies were designed according to Eurocodes and subjected to a deep structural analysis, aiming to evaluate the effective allowable ductility (behaviour factor) with respect to what imposed during the design phase.