Typology of NSPA Pushover Curves and Surfaces for 3D Performance-Based Seismic Response of Structures

Abstract

This paper presents a typology of pushover curves and the originally developed pushover surfaces based on the generalization of the nonlinear response of the 3D system to the earthquake action. By determination and analysis of the NSPA (Nonlinear Static Pushover Analysis) pushover surface, it is possible to obtain a more complex and a more complete insight of the response and performance of 3D models of structures exposed to the bidirectional seismic action. The setting which served as a base for the development of the mathematical formulation and generation of the NSPA pushover surface presents the application of NSPA pushover curve for the response of the system in one direction. By integrating the system responses for a number of directions, i.e. attac angles of directions of earthquake action, the presentation of the 3D response of the system in the capacity domain is achieved. The typology of NSPA pushover curves is derived as a function of the existence of linear, nonlinear and collapse subdomain, and also considerations are made taking into account the nonlinear stiffness and ductility class of the system. The typology of NSPA pushover surface is derived based on the generalized model of the system response through ductility, ductility in hardening/softening zone and a coefficient of the relationship of stiffness in the nonlinear and linear domain, based on which it is possible to create systems of different stiffness, strength and ductility. The research presented in this paper defines the typological models of NSPA pushover surfaces based on which further discussion can be done on real pushover surfaces of 3D models of structures with a more complex, particularly non-symetric geometry, as well as variation of responses of the system due to bidirectional seismic actions.