Test of an Idea for Setting the Nonlinearity Tolerance in Nonlinear Response History Analyses According to Procedures Originated in the Seismic Code of New Zealand NZS 1170.5:2004

Abstract

Nonlinear response history analysis using an integration scheme and an iterative nonlinear solution method is a versatile tool for analyzing structural systems subjected to earthquakes. Nevertheless, the resulting responses are inexact and the analyses are generally complicated and computationally expensive. In a recent study, a slight change is applied to the continuation/end of the nonlinear solutions' iterations and the probable stop of the analysis. As a result, the simplicity and efficiency of the analysis according to the seismic code of New Zealand NZS 1170.5:2004 is enhanced, without negative effects on the response accuracy. In this paper, in order to simplify the analysis further, and under the assumption of piecewise linear behavior, three simple suggestions for setting the nonlinearity tolerance are tested. Consequently, when the response history analysis is based on repetition of time integration analysis, as it is in the seismic code of New Zealand, NZS 1170.5:2004, the nonlinearity tolerance can be simply set and reduced with each new repetition. Such selections not only simplify the analysis by eliminating the concerns on the nonlinearity tolerance, but also may reduce the computational effort. The reduction in computational effort may be considerable specifically when the behavior is highly nonlinear. The added simplicity can increase the interest in using response history analysis in earthquake engineering practice, as well.