Coupled Systems Mechanics, Vol. 6, No. 4 (2017) 501-522 DOI: https://doi.org/10.12989/csm.2017.6.4.501 501 Copyright © 2017 Techno-Press, Ltd. http://www.techno-press.org/?journal=csm&subpage=8 ISSN: 2234-2184 (Print), 2234-2192 (Online) Iterative global-local approach to consider the local effects in dynamic analysis of beams R. Emre Erkmen * and Ashkan Afnani a School of Civil and Environmental Engineering, University of Technology, Sydney, 15 Broadway, Ultimo NSW 2007, Australia (Received November 9, 2016, Revised November 13, 2017, Accepted November 14, 2017) Abstract. This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis. Keywords: iterative global-local method; multi-scale analysis; finite elements; elasto-plastic behavior; structural dynamics 1. Introduction There is a need for computationally efficient structural dynamic analysis methods to gain savings in analysis time as well as in the post-processing of the results, despite significant advances in computer performances. It is possible to improve the accuracy of the numerical results by refining the model only in a local region without changing the global simpler model of the whole structure (Knight et al. 1991, Mao and Sun 1991, Mote 1971, Noor 1986). Simple beam elements are often used in the modelling of frame type structures, such as buildings or bridges, since frame-type structures are composed of beams and columns that have one dimension relatively large in comparison to the cross-sectional dimensions. Simple beam-type elements, however, are based on the assumption of rigid cross-section and thus, they cannot consider the deformations of the cross-section. On the other hand, local effects in beams may interact with the global behaviour to produce early yielding and reduction in strength. Overlapping decomposition Corresponding author, Ph.D., E-mail: emre.erkmen@uts.edu.au a Ph.D., E-mail: ashkan.afnaniesfandabadi@student.uts.edu.au