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Structural Engineering and Mechanics, Vol. 51, No. 6 (2014) 1017-1036 DOI: http://dx.doi.org/10.12989/sem.2014.51.6.1017 1017

Copyright © 2014 Techno-Press, Ltd. http://www.techno-press.org/?journal=sem&subpage=8 ISSN: 1225-4568 (Print), 1598-6217 (Online)

Improving buckling response of the square steel tube by using steel foam

Mohammadreza Moradi1 and Sanjay R. Arwade2a

1Department of Civil and Environmental Engineering, Old Dominion University, Norfolk, VA, 23529, USA

2Department of Civil and Environmental Engineering, University of Massachusetts, Amherst, MA, 01003, USA

(Received October 15, 2012, Revised July 1, 2014, Accepted July 2, 2014)

Abstract. Steel tubes have an efficient shape with large second moment of inertia relative to their light weight. One of the main problems of these members is their low buckling resistance caused from having thin walls. In this study, steel foams with high strength over weight ratio is used to fill the steel tube to beneficially modify the response of steel tubes. The linear eigenvalue and plastic collapse FE analysis is done on steel foam filled tube under pure compression and three point bending simulation. It is shown that steel foam improves the maximum strength and the ability of energy absorption of the steel tubes significantly. Different configurations with different volume of steel foam and composite behavior is investigated. It is demonstrated that there are some optimum configurations with more efficient behavior. If composite action between steel foam and steel increases, the strength of the element will improve, in a way that, the failure mode change from local buckling to yielding.

Keywords: steel foam;; steel tube;; plate buckling;; imperfection;; finite element analysis 1. Introduction

Steel tube beams and columns are able to provide significant strength for structures. They have

an efficient shape with large second moment of inertia which leads to light elements with high bending strength. Moreover, they can resist loading in multiple directions, and have large torsional strength. One of the drawbacks of tubular cross sections with thin walls is their susceptibility to local buckling. Having thin walls forces the element to buckle locally before the cross section can show its maximum capacity through full yielding. Moreover, this local buckling will cause low ductility in the element response.

One method of increasing the ductility and capacity of tubular elements is filling them with another material. One of the classical materials which is used for this purpose is concrete. There are large numbers of studies on the behavior of concrete-filled columns and beam-columns such as the research done by Furlong (1967), Shakir-Khalil and Mouli (1990), Prion and Boehme (1994), Schneider (1998), Varma et al. (2002), Han (2004), Lu et al. (2007), Chitawadagi and Narasimhan (2009), Chen et al. (2012), Chacon et al. (2013) which show that there is a substantial

Corresponding author, Lecturer, E-mail: [email protected] aAssociate Professor, E-mail: [email protected]

Mohammadreza Moradi and Sanjay R. Arwade

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