Influence of moisture induced stresses in steel-to-timber dowel joints

摘要

Several cases of serious cracking failures have occurred in timber structures in the Nordic countries. Some of these failures seem to be caused by prevented movements in joints while subjected to high moisture variations during the construction period. Dowel-type fasteners are common joints in timber structures and the influence of moisture induced stresses on such joints needs to be studied. The trend towards larger and more complex timber structures increases the need further due to the number of structural failures being reported. In this paper results from experimental tests of the influence of prevented moisture movements in minor dowel-type fasteners are presented. The joints consisted of slotted-in steel plates fixed with two dowels. They were placed in climate chambers were they were subjected to controlled moisture variations. During the conditioning, the strain fields in the connection area were measured with a contact-free technique and compared with a reference group of joints without constraints. Tests of the load capacity were performed after storage in climate chambers to find out if the prevented moisture movements affect the load-slip behaviour.