Strengthening of timber structures with glued-in rods

Published Date
30 October 2015, Vol.97:90–105, doi:10.1016/j.conbuildmat.2015.03.097
Special Issue: Reinforcement of Timber Structures

Author 

René Steiger ^a,,,www 

Erik Serrano ^b,1,,www 

Mislav Stepinac ^c,2,,www 

Vlatka Rajčić ^c,3,,www 

Caoimhe O’Neill ^d,4,,www 

Daniel McPolin ^d,5,,www 

Robert Widmann ^a,6,,www

• aEmpa, Swiss Federal Laboratories for Materials Science and Technology, Structural Engineering Research Laboratory, Ueberlandstrasse 129, CH-8600 Dübendorf, Switzerland
• bDivision of Structural Mechanics, Faculty of Engineering LTH, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
• cDepartment of Structures, Faculty of Civil Engineering, University of Zagreb, Kaciceva 26, 10 000 Zagreb, Croatia
• dCivil Engineering Research Centre, Queen’s University, Belfast University Road, Belfast BT9 5AG, Northern Ireland, United Kingdom

Received 28 January 2015. Revised 17 March 2015. Accepted 23 March 2015. Available online 20 April 2015.

Highlights

• Glued-in rods (GiR) connections/reinforcement to be regarded as systems.
• •
  System parts: timber, rod, adhesive, geometry, setting procedure, quality control.
• •
  Ductile failure modes in GiR to be preferred.
• •
  Few technical approvals for specific products available.
• •
  Limited number of design rules in actual and former design codes available.

Abstract 

The research and development of connecting and strengthening timber structural elements with glued-in rods (GiR) has been ongoing since the 1980s. Despite many successful applications in practice, agreement regarding design criteria has not been reached. This state-of-the-art review summarises results from both research and practical applications regarding connections and reinforcement with GiR. The review considers manufacturing methods, mechanisms and parameters governing the performance and strength of GiR, theoretical approaches to estimate their load-bearing capacity and existing design recommendations.

Keywords

Reinforcement

Steel rod

FRP rod

Design

Application

Adhesive

Eurocode 5

Quality control

Linear elastic fracture mechanics

Non-linear elastic fracture mechanics

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  Corresponding author. Tel.: +41 58 765 42 15.
  
  

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Mixed mode fracture of glued-in rods in timber structures

Published Date
Original Paper

First Online: 

30 December 2014

DOI: 10.1007/s10704-014-9986-9

Cite this article as: 

Lartigau, J., Coureau, JL., Morel, S. et al. Int J Fract (2015) 192: 71. doi:10.1007/s10704-014-9986-9

Author

Julie Lartigau

Email author

Jean-Luc Coureau

Stéphane Morel

Philippe Galimard

Emmanuel Maurin

Abstract

Glued-in-rods in timber structures lead to overcome the use of traditional bolted connections, preserve a large part of the original timber and offer aesthetic benefits. Several research programs were achieved to improve the mechanical knowledge of this technique, exhibiting experimentally the influence of materials and the effect of the geometric configuration. From these experimental results, some design rules predicting the axial strength are available, but a common criterion is still lacking. This paper relates to experimental investigations and finite element computations on glued-in rods, with the aim of providing a better knowledge about their mechanical behavior until failure. An experimental campaign is carried out on single glued-in rod connections. The finite element modeling reproduces the experimental configuration: it exhibits significant normal stress (to the interface) at the onset of the bonding, in comparison with shear stress. Within the framework of equivalent linear elastic fracture mechanics, resistance curves in mode I and mode II are established for each specimen. Finally, a mixed mode fracture criterion (I/II) is used to describe the fracture process zone development at the wood-adhesive interface (failure zone). An analytical formulation is then proposed allowing the evaluation of peak load of each specimen, which highlights a new approach for the design of such connections.

Keywords

Glued-in rodsMixed mode fractureEquivalent LEFMCrack closure techniqueR-curve

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