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Delamination Detection in a 90-Year-Old Glulam Block with Scanning Dry Point-Contact Ultrasound

https://research.thinkwood.com/en/permalink/catalogue114
Year of Publication
2013
Topic
Connections
Material
Glulam (Glue-Laminated Timber)
Author
Neuenschwander, Jürg
Sanabria, Sergio
Schuetz, Philipp
Widmann, Robert
Vogel, Mareike
Organization
Swiss Federal Laboratories for Materials Science and Technology
Publisher
De Gruyter
Year of Publication
2013
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Keywords
Bonding
Delamination
Inspection
Non-Destructive Evaluation
Research Status
Complete
Series
Holzforschung
Summary
Glued laminated timber (glulam) is known in timber constructions since more than 100 years. Glulam members can delaminate due to aging and excessive changes of temperature and humidity. This results in significantly reduced load bearing capability of the affected structural members. This contribution focuses on the ultrasonic point-contact inspection of gluing plane delamination as a nondestructive method. Ultrasonic measurements on a section of a 90-year old roofing glulam member are presented. The results are compared with manual detection and evaluation of delamination with a feeler gauge, with X-ray computed tomography analyses, and with numerical simulations. Appropriate data evaluation of the mechanized ultrasonic results allows the determination of material separation that are deeper than 20 mm in the signature of the surface wave and large-scale delamination (> 80% of the complete bonding width) in the back-wall echo. Numerical simulations based on the finite-difference time-domain method shed light into the details of the wave propagation and support the experimental findings.
Online Access
Free
Resource Link
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Long Term Monitoring of Timber Bridges - Assessment and Results

https://research.thinkwood.com/en/permalink/catalogue2124
Year of Publication
2013
Topic
Moisture
Serviceability
Application
Bridges and Spans
Author
Franke, Bettina
Franke, Steffen
Müller, Andreas
Vogel, Mareike
Scharmacher, Florian
Tannert, Thomas
Publisher
Scientific Net
Year of Publication
2013
Format
Journal Article
Application
Bridges and Spans
Topic
Moisture
Serviceability
Keywords
Monitoring
Bridge
Moisture Content
Climate
Research Status
Complete
Series
Advanced Materials Research
Summary
Timber bridges have been built for decades all around the world. The hygroscopic material behavior of wood leads to the change of the moisture content of the wood and the dimensions depending on the climate. Therefore in regular inspections following questions arise: what happens with the wood due to the climate changes? Are there major changes of the moisture content? Are there differences between the natural material axes or within the cross section of the structural members? To answer these questions, traffic timber bridges with big cross sections are long-term monitored within a research project. The results of the moisture contents measured and a comparison between the different measuring groups and positions are presented. The analyses confirm that the moisture content in the wood follows the climate changes delayed and with smaller amplitude against the calculated equilibrium moisture content. In first steps, a different behavior of the change of the moisture content could be determined over the cross-section and along the span of the member.
Online Access
Payment Required
Resource Link
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