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Accessible Unlicensed Requires Authentication Published by De Gruyter June 1, 2005

Internal stresses in glulam due to moisture gradients in the grain direction

Johan Hans Jönsson
From the journal


An experimental study on the internal stress state perpendicular to grain in glued laminated timber induced by moisture variations along the grain is presented. The stress is evaluated by using measured modulus of elasticity and strain. Different types of tests are performed, in which specimens are exposed to artificial climate change when the specimens are in either a wetting or a drying state, and specimens are exposed to a cyclic climate change. Test results from the specimens that were in a drying state show that the tensile stresses near the end of the specimens at some point exceeds the strength of the wood and cracks. In the opposite test, when the specimens are in a moistening phase, the maximum tensile stresses are lower and in the order of 0.2 MPa during the tested period. The cyclic test, which continued during 20 weeks, showed that there were no accumulated effects regarding strain and stress values. In this test, the average maximum tensile and compression stresses were of the order 0.20 and 0.10 MPa, respectively.


Corresponding author. Department of Structural Engineering, Lund Institute of Technology, P.O. Box 118, SE-221 00 Lund, Sweden.


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Published Online: 2005-06-01
Published in Print: 2005-01-01

©2004 by Walter de Gruyter Berlin New York