On the Essentiality of Techniques to Enlarge Integration Steps in Transient Analysis Against Digitized Excitations

In transient analysis against digitized excitations, and specially, practical seismic analyses, the steps, by which, the strong ground motions are digitized, might be smaller than those recommended for the accuracy of integration. In these cases, in order to consider the total excitation information, the integration steps are to be set as small as the excitation steps. The result is extra computational cost. In the last decade, techniques are proposed, to provide the capability of time integration with larger steps, without disregarding the excitations information. Though the resulting responses are sufficiently accurate, a fundamental question persists. It is on the loss of accuracy, when we simply omit the inter-integration-step excitations. This paper is dedicated to this concern, in the area of seismic analysis. The study is carried out, through theoretical discussions and numerical examples. As the consequence, omission of inter-integration-step excitations may impair the responses, the inaccuracies can be significant, and even, halts of analyses are expectable, in nonlinear analyses. Implementation of techniques for enlargement of integration steps can lead to more efficient and more reliable analyses.