Skip header and navigation

3 records – page 1 of 1.

Failures in Large-Span Roof Structures in Switzerland

https://research.thinkwood.com/en/permalink/catalogue296
Year of Publication
2013
Topic
Design and Systems
Material
Glulam (Glue-Laminated Timber)
Application
Roofs
Author
Steiger, René
Herwig, Andrin
Widmann, Robert
Piskoty, Gabor
Year of Publication
2013
Country of Publication
Netherlands
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Roofs
Topic
Design and Systems
Keywords
Large Span
Failure
Switzerland
Language
English
Conference
International Association for Bridge and Structural Engineering Symposium
Research Status
Complete
Notes
May 6-8, 2013, Rotterdam, Netherlands
Summary
The present paper describes collapses and failures of three large-span roof structures in Switzerland: In February 2009 the steel roof of a three years old gym in eastern Switzerland collapsed. Based on visual findings and on a detailed investigation it could be found that the cause of the collapse was a deficient detailing in each of the seven 26 m long, simply supported main steel plate girders. The collapse was triggered by increasing snow load although at the day of collapse the load was 25% lower than the characteristic value according to the Swiss design code. In November 2003 the roof of a timber multi-purpose hall partly collapsed after a period of rain. The investigations showed that the most relevant reason for the collapse was the incorrect execution of welds at the joints of supporting shoes in conjunction with the marginal design of that detail. From other factors that contributed to the collapse an insufficient drainage system of the roof could be identified as having played an important role. In 2011 a 180 x 1120 mm2 glued-laminated timber beam with a span of 18 m being part of the secondary structural system supporting the flat roof of a DIY superstore near Zurich failed in bending. The failure had been triggered to a considerable extent due to overloading of parts of the roof by a gravel layer compared to other parts of the roof being of higher depth and specific weight. From all three incidents it could be concluded that a closer orientation of the design to available design codes and a strict quality control during design, execution and use of the building would have reduced the probability of collapse / failure of the roof structures considerably.
Online Access
Free
Resource Link
Less detail

Field Measurement of Vertical Movement and Roof Moisture Performance of the Wood Innovation and Design Centre

https://research.thinkwood.com/en/permalink/catalogue1638
Year of Publication
2016
Topic
Moisture
Serviceability
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
PSL (Parallel Strand Lumber)
Application
Roofs
Wood Building Systems
Author
Wang, Jieying
Karsh, Eric
Finch, Graham
Chen, Mingyuk
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
PSL (Parallel Strand Lumber)
Application
Roofs
Wood Building Systems
Topic
Moisture
Serviceability
Keywords
Moisture Content
Vertical Movement
Temperature
Relative Humidity
Monitoring
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3152-3160
Summary
The Wood Innovation and Design Centre (WIDC) in Prince George, British Columbia, with 6 tall storeys and a total height of 29.5 m, provided a unique opportunity for non-destructive testing and monitoring to measure the ‘As Built’ performance of a relatively tall mass timber building. The mass timber structural system consists of glulam columns and beams with cross laminated timber (CLT) floor plates and shear walls. Vertical movement of selected glulam columns and CLT walls and the moisture content of the innovative mass timber roof were monitored as these components are unique to mass timber buildings. Indoor temperature and relative humidity conditions were also measured. The mass timber CLT and glulam elements are susceptible to longer-term differential movement as they slowly dry after manufacturing and construction. The paper describes instrumentation and discusses the measurement results for two years following the topping out of the structure. The monitoring indicated that the wood inside the building could reach a moisture content (MC) close to 4% in the winter in this cold climate, from an initial MC of around 13% during construction. Glulam columns were dimensionally stable in the longitudinal direction given the MC changes and loading conditions. With a height of over 5 m and 6 m, respectively, two glulam columns directly measured by sensors each showed vertical movement below 3 mm (i.e., 0.04%). The cumulative shortening of the six glulam columns along the height of the columns (24.5 m) is expected to be approximately 11 mm. This did not take into consideration any potential settlement or deformation at connections between glulam columns, or effects of reduced loads on the top two unoccupied floors. The CLT wall panels were also dimensionally stable along the height of the building, with cumulative vertical shrinkage of about 19 mm (i.e., 0.07%) from Level 1 to Level 6. In contrast, the 5-ply CLT floor slabs made up of wood in radial and tangential grain shrank in thickness by about 5 mm (3.0%) on average. With regards to the performance of the mass timber roof, the CLT roof panels started out dry and remained dry due to the robust assembly design and the dry indoor conditions. In one area the plywood roof sheathing was initially wetted by the application of a concrete topping below a piece of mechanical equipment, it was able to dry to the interior within a few months. Overall the monitoring study showed that the differential movement occurring among the glulam columns and the CLT wall was small and the mass timber roof design had good drying performance.
Online Access
Free
Resource Link
Less detail

Wetting and Drying Performance of Wood-Based Assemblies Related to On-Site Moisture Management

https://research.thinkwood.com/en/permalink/catalogue1782
Year of Publication
2016
Topic
Site Construction Management
Moisture
Material
CLT (Cross-Laminated Timber)
NLT (Nail-Laminated Timber)
Application
Floors
Roofs
Author
Wang, Jieying
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
NLT (Nail-Laminated Timber)
Application
Floors
Roofs
Topic
Site Construction Management
Moisture
Keywords
Moisture Content
Wetting
Drying
Construction
Climate
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 5554-5563
Summary
This document aims to emphasize the importance of an appropriate level of on-site moisture management for wood construction, depending on weather conditions, construction methods, and assemblies used. It covers three different but related research projects. It first describes baseline moisture contents (MCs) measured from...
Online Access
Free
Resource Link
Less detail