Typology of NSPA pushover curves and surfaces for 3D performance-based seismic response of structures

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 complete insight of the response and performance of 3D models of structures exposed to the bidirectional seismic action. The setting which was a base for the development of 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. attack angles of directions of earthquake action, the presentation of 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 sub domain, 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 which can be the base of further discussion on real pushover surfaces of 3D models of structures with a more complex, particularly non-symmetric geometry, as well as the variation of responses of the system due to bidirectional seismic actions.