Muthulakshmi Gowtham:

The seismic performance of structure can be assessed with different levels of computational efficiency depending on available data and resources. Detailed nonlinear analyses (static or dynamic) are required to be carried out for assessing seismic capacity and performance of structures for a given hazard or demand.

It is a common practice to use simple nonlinear static analysis procedures or pushover analysis for performance evaluation of structure using Capacity Spectrum Method, Displacement Coefficient Method, or the N2 method. On the other hand, the structural response to a particular ground motion or a set of ground motions can be obtained by nonlinear time-history analysis, also known as nonlinear dynamic analysis. Several methods have been used for nonlinear dynamic analyses, such as incremental dynamic analysis, multiple stripe analysis, cloud analysis, etc.

The nonlinear dynamic methods to a certain extent are suitable for evaluating the relationship between the engineering demand parameter; however, their application can be quite time-consuming as the nonlinear dynamic analyses are usually repeated for several ground motions for increasing levels of intensity measure. Therefore, nonlinear static analysis procedures are hugely popular and more feasible for seismic performance assessment of structures, especially the first-mode predominant structures.

Dear Muthulakshmi Gowtham

Nonlinear analysis is usually used to assess performance of existing structures or structures equipped with control systems, and also in order to evaluate structural collapse, so this procedure is often used in research works or special and important structures.

In general Nonlinear Dynamic Procedure (NDP) is the most complete and accurate type of analysis and as a result this method has no limitations but its challenges are record selection and high computational effort, also it requires considerable judgment and experience to perform and its results should be reviewed by experts. Incremental Dynamic Analysis (IDA) and Endurance Time (ET) method are among the methods can be used to perform NDP.

The Nonlinear Static Procedure (NSP often called pushover analysis) uses simplified nonlinear techniques to estimate seismic structural deformations but it has some limitations to use.Therefore, NSP is more feasible and less accurate than NDP if this method can be utilized according to its limitations.

For more information, see Chapter 7 of ASCE 41-13.

Current FEM software included PushOver analysis, as a part of the analysis procedure. They also give some standard hinge properties, as default option. Expert user will be able to tweak these properties, for better accuracy. It is simple, consumes less resources, and reasonably accurate for regular / symmetric / simple structures, where mass and stiffness eccentricity is minimum. For other complex cases, detailed dynamic analysis, in the form of Response Spectrum or Time History, will give results with better accuracy.