Stiffness-Strength-Ductility Design Approach: an application to a five-storey steel building structure

摘要

It is known that the seismic response of a structural system is highly influenced, in addition to thernearthquake input, by the dynamic characteristics of the system itself. Many recent contributions inrnthe field of seismic engineering have opened up new possibilities for the structural engineer inrnterms of conceiving and designing a structural system which offers optimised seismic performances.rnThis paper presents an innovative approach for an optimised/full-controlled seismic design ofrnstructures which combines these recent contributions, and overcomes the traditional designrnapproach leading to the identification of the characteristics of the structural system resisting tornhorizontal loads which enables to satisfy given seismic performance objectives. This is achieved byrnconsidering a total conceptual separation between the structural systems resisting to vertical andrnhorizontal loads. The proposed procedure is first briefly developed in general within a PBSDrnframework and then fully applied to the case study of a five-storey steel building structure. It isrncomposed of three basic steps: (1) calibration of the fundamental characteristics (Stiffness, Strength,rnDuctility) which should be possessed by the structural system resisting to the horizontal loads tornsatisfy given performance objectives, (2) identification of the physical and geometricalrncharacteristics of the single structural elements which constitute the horizontal resisting system, (3)rnverification, by means of appropriate time-history analyses, of the seismic performances achieved.rnIn detail, the horizontal resisting system is calibrated to satisfy a multiplicity of performancernobjectives through the identification of an "objectives curve", in the Force-Displacement diagram,rnof the mechanical characteristics of the structure. The calibration is obtained by methods/toolsrnborrowed either from DDBD or Force-Based Design (FBD), depending on the specific performancernobjective to be imposed.