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

Cosic M., Brcic S.: Typology of NSPA Pushover Curves and Surfaces for 3D Performance-Based Seismic Response of Structures (presentation)

This presentation shows 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.

Seismic Methods

Folic R., Cosic M.: Seismic Methods (presentation)

The authors of the presentation, on the basis of the analysis of several thousand scientific papers, presented their original systematization of nonlinear seismic methods for structural performance analysis, which were developed in the last twenty years. Nonlinear seismic methods are generally classified into two groups: Nonlinear Static Analyses (NSA) and Nonlinear Dynamic Analyses (NDA). The analyses of non linear seismic structural response were classified separately from the target displacement analysis which defines the relationship of the seismic demand and the seismic response. On the other hand, the classification was also conducted depending on whether a nonlinear response of the system is obtained by the implementation of incremental-iterative procedures or by the implementation of semi-iterative and/or semi-incremental procedures. Nonlinear Dynamic Analyses were classified according to the concept of mathematical formulation, i.e. whether they are based on only one dynamic analysis, several dynamic analyses or are solved in combination with other methods. By implementing the conducted systematization and classification of nonlinear seismic methods, on can very efficiently consider which type of method is optimal for structural analysis and which type of method should be taken into account in the phase of preliminary and final analyses in the course of scientific research and professional projects.

Nonlin Quake software

Cosic M., Brcic S., Folic R., Susic N.: Nonlin Quake Software (presentation)

The presentation shows the original developed software NonlinQuake for performance-based seismic analysis of 3D structural models. Software Nonlin Quake consists of several independent compatible softwares that implements: create a database of two componential ground motion records (GMR), generation and processing of multicomponential GMR, creating incomplete and complete nonstationary artificial accelerograms, deterministic and probabilistic seismic hazard analysis, generation and processing of multicomponential response spectras, analysis of design parameters, processing of pushover curves and surfaces, calculation based on hybrid incremental nonlinear static-dynamic analysis, target displacement analysis, analysis and scaling of response spectras and analysis of target displacement envelope. For four considered methods for analysis of system performances: nonlinear static pushover analysis (NSPA), incremental nonlinear dynamic analysis (INDA), incremental dynamic analysis (IDA) and hybrid incremental nonlinear static-dynamic analysis (HINSDA), flow charts are shown.

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