Provisions for Ductile Behavior of Timber-to-Steel Connections with Multiple Glued-In Rods
Publication: Journal of Structural Engineering
Volume 139, Issue 9
Abstract
Connections with glued-in rods are very efficient, high-strength joints and can be successfully used, for example, for the anchorage of vertical timber elements to a foundation. Although extensive research was done on the pullout strength of single rods, few references can be found on the behavior of multiple glued-in rods. This paper presents the results of an experimental program carried out on timber-to-steel connections with multiple glued-in rods. Two series of 10 specimens with four large-diameter, glued-in rods made from mild steel (Series GB) and 10 specimens with 12 small-diameter, high-grade glued-in rods (Series GS) were tested to failure under monotonic tensile load. Both types of connections ultimately failed in a brittle manner; however, the GB series developed some plastic deformations prior to failure which was caused by the pullout of two rods and longitudinal splitting of the timber member. By comparing the experimental results with the analytical predictions, no significant group effect could be detected in the GB test series, and an overall acceptable approximation was found. In the GS test series, no final conclusion on the group effect could be drawn as several rods failed by nut-stripping. A parametric study using analytical formulas was carried out to investigate the effect of rod strength, rod diameter, glued length, and timber density on the connection performance. Based on the results of the parametric study and experimental tests, it can be concluded that the use of mild steel as well as more rods of larger diameter, properly spaced from each other, and from the edges are all effective measures to increase the connection ductility. Furthermore, by leaving a suitable length of rod unbonded between the steel plate and the glued length, it is possible to control ductility, providing all brittle failure modes have a higher strength capacity than the rod-yielding force. Special care should be taken during the manufacturing process to ensure good quality of gluing (required glued length and amount of adhesive) and rod alignment.
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Acknowledgments
The writers thank Moelven Töreboda AB for the collaboration that made this research possible. The Centre for Lean Wood Engineering and The Swedish Governmental Agency for Innovation Systems (VINNOVA) are acknowledged for their financial and kind support. The sincere help of the staff at Complab, Luleå University of Technology is gratefully acknowledged. The experiments were supported by European Union Structural Funds, which is gratefully acknowledged.
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Information
Published In
Journal of Structural Engineering
Volume 139 • Issue 9 • September 2013
Pages: 1468 - 1477
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Oct 31, 2011
Accepted: Sep 10, 2012
Published online: Sep 13, 2012
Published in print: Sep 1, 2013
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