Structural behavior checks prior performing nonlinear dynamic analysis

Abstract

Students, researchers, and practicing engineers regularly use mathematical models to evaluate the seismic behavior of structures. Advances in the capacity of computer storage capacity and processing speed have allowed these models to be more complex in terms of model extent and analytical features. As a result, evaluation of structures using nonlinear dynamic analyses is more common and even required under certain circumstances. However, one of the possible consequences of having the technology to model complicated structures and behavior is that errors can be committed in the process. Moreover, there is a tendency to perform the most complicated response evaluation once the model has been completed. Thus, little or no understanding of the structure's behavior is acquired, which could lead to invalid results and could waste a considerable amount of time. The probability of having errors in an analysis is increased where the analysis software does not have a graphical user interface, as is the case with OpenSees. Therefore, in this study, a variety of validation tools and checks that can provide an understanding of behavior and confidence in the computed results are presented. While the procedure is generic (applies to all structures), it is demonstrated by example analysis of a 4-story steel system. Analysis is performed in three dimensions in OpenSees. The validation procedure, presented as a checklist, includes: modal analysis, free vibration analysis, nonlinear static pushover analysis, and nonlinear dynamic analysis. All analyses are performed with and without second order effects, and with and without inherent damping. The conclusion from this study is that the proposed validation tools give the researcher or the structural engineer the confidence required to perform more complicated analyses, and to trust the obtained results. © NCEE 2018.All rights reserved.