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Building Climate – Long-Term Measurements to Determine the Effect on the Moisture Gradient in Timber Structures

https://research.thinkwood.com/en/permalink/catalogue266
Year of Publication
2014
Topic
Serviceability
Moisture
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Gamper, Andreas
Dietsch, Philipp
Merk, Michael
Organization
Technical University of Munich
Year of Publication
2014
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Serviceability
Moisture
Keywords
Moisture Gradients
Climate
Load Carrying
Research Status
Complete
Summary
Through long-term measurements of climate data (temperature, relative humidity) and timber moisture content on large-span timber structures in buildings of typical construction type and use, data sets were generated which deliver information on the sequence and magnitude of seasonal variations. The measurement of moisture in different depths of the cross-section is of particular interest to draw conclusions on the size and speed of adjustment of the moisture distribution to changing climatic conditions. The moisture gradient has direct influence on the size of the internal stresses and possible damage potential. Similarly, the results provide a review and extension of the previous classification of buildings into use classes. They allow for a more precise indication of range of resulting equilibrium moisture content for the specific use, enabling the installation of timber elements with adjusted moisture content. The results of the research project also support the development of appropriate monitoring systems, which could be used in the form of early warning systems based on climate measurements
Online Access
Free
Resource Link
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Experimental Investigation on the Shear Resistance of Existing Glulam Structures

https://research.thinkwood.com/en/permalink/catalogue2439
Year of Publication
2019
Topic
Design and Systems
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Schulte-Wrede, Michael
Merk, Michael
Dietsch, Philipp
Organization
Technical University of Munich
Year of Publication
2019
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Shear Resistance
Bending Tests
Aging Processes
Drill Cores
Conference
International Conference on Structural Health Assessment of Timber Structures
Research Status
Complete
Summary
Numerous large-span, load-bearing structures, e.g. for public venues, sports halls or industrial facilities, utilize glued-laminated timber (glulam) due to its versatility and aesthetic appearance. Since glulam is an organic and composite material consisting of wooden lamellas joined with glue, mistakes during planning, fabrication and use of the structure can lead to deficiencies or even damages. Following a visual inspection suitable to detect surface deterioration, further holistic investigation of the glulam material is necessary to appraise structural safety or estimate the need for restoration. Besides the integrity of the wooden lamellas, the glue bond of the lamellas is vital for the operational reliability of glulam. A currently practiced, semi-destructive assessment method to revalue the condition of the glue lines consults a shear test on drill core samples with included glue line. The presented paper links this method to medium-scale shear tests and large-scale 3-Point bending-shear tests representing a practical loading situation. To provoke shear failure during bending, reinforcements of the specimens at critical tension and compression zones included glued-on beech veneer lamellas and self-tapping screws, respectively. Executed on the same sample material, shear resistance was determined for all three testing formats. The sampling included aged and new glulam. Published values derived from comparable test programs augmented the database. Based on the evaluated test results of the drill cores under shear loading, suggestions regarding the drill core extraction and the implementation of the valuation method of EN 14080 are outlined. After incorporating a size effect to account for varying dimensions of the bendingshear specimen, their shear resistance values correlated well with the obtained values from the drill core tests. This adumbrates the possibility to derive the shear resistance of structural members from shear values of drill core samples taken from an existing glulam structure.
Online Access
Free
Resource Link
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Structural Safety and Rehabilitation of Connections in Wide-Span Timber Structures - Two Exemplary Truss Systems

https://research.thinkwood.com/en/permalink/catalogue1485
Year of Publication
2008
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Bridges and Spans
Author
Dietsch, Philipp
Merk, Michael
Mestek, Peter
Winter, Stefan
Organization
Technical University of Munich
Year of Publication
2008
Format
Report
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Bridges and Spans
Topic
Connections
Mechanical Properties
Keywords
Failure Mechanisms
Wide-Span
Cracks
Glue Lines
Strength
Research Status
Complete
Summary
Following the Bad Reichenhall ice-arena collapse, numerous expertises on the structural safety of wide-span timber structures were carried out at the Chair of Timber Structures and Building Construction. It became evident that inadequate structural design and detailing as well as inadequate manufacturing principles were the main reasons for observed failures. The design and manufacture of connections in wide-span timber structures are still amongst the most challenging tasks for both the structural engineer as well as the executing company. This paper will, on the basis of two exemplary expertises, discuss specific issues in the structural reliability of connections in wide-span timber trusses and give recommendations towards a state-of-the art design of such connections.
Online Access
Free
Resource Link
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