New methods for assessment and design of structures in seismic zones: present state and research needs
Significant advances have been accomplished in the last decade in the seismic protection of structures, based on the introduction and refinement of innovative conceptual approaches. The main drawbacks and inconsistencies related to traditional force-based design approach have been recognized as well as the critical role of displacement or deformation demand in characterizing the structural damage and thus the performance of the system when subjected to different level of ground motion intensity. A common generalized trend of developing and adopting displacementldeformation- based approaches within a performance-based design philosophy has resulted. In this contribution, a state-of-the-art critical review of the current research developments in seismic design and assessment methods based on performance based philosophy, either purely or partially relying on displacement-based or deformation-controlled approaches, will be provided. The influences on recent major code revisions and modifications, as well as on preliminary design guidelines, will be discussed, while reviewing the conceptual fundaments of the different approaches and underlining main sources of uncertainties and possible future developments.