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Bending Tests on Glued Laminated Timber Beams with Well-Known Material Properties

https://research.thinkwood.com/en/permalink/catalogue186
Year of Publication
2013
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Fink, Gerhard
Kohler, Jochen
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2013
Country of Publication
Switzerland
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Bending Strength
Failure
Load Bearing Capacity
Four Point Bending Test
Density
Model
Bending Stiffness
Language
English
Research Status
Complete
Summary
At the Institute of Structural Engineering at the ETH Zurich numerous of investigations are conducted to analyse the load bearing capacity of glued laminated timber beams. The investigations are part of the research project ’Influence of varying material properties on the load bearing capacity of glued laminated timber (glulam)’. The investigations are taking place on 24 glulam beams with well-known material properties. The glulam beams are fabricated out of 400 timber boards. From those boards the material properties are investigated non-destructively within a former research project. During the glulam fabrication it is particularly focused to keep the information of the timber boards; i.e. after the glulam fabrication the position of each particular timber board within the glulam beam and thus the position of each particular knot is still known. The glulam beams are investigated during a 4-point bending test. On the glulam members the load bearing capacity, the bending stiffness and the density is measured. Furthermore local strains within the glulam beams are investigated using an optical coordinate-measurement device. Following the test the failure is investigated in detail. Hereby the type of failure (knot cluster, finger joint, clear wood) and the amount of failure (number of damaged lamellas) is documented. Afterwards the failed glulam beams are loaded again to analyse the remaining bending strength and the corresponding remaining bending stiffness. The major aim of the experimental analysis is the investigation of the load bearing capacity of glulam beams with well-known local material properties. The gained results can be used for an investigation of the influence of local weak zones, such as knot clusters or finger joints, on the load bearing capacity of glulam. In addition a data basis is produced to develop a new model (or to evaluate existing models) for the estimation of the load bearing capacity of glulam.
Online Access
Free
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A holistic framework for designing for structural robustness in tall timber buildings

https://research.thinkwood.com/en/permalink/catalogue2853
Year of Publication
2021
Topic
Design and Systems
Material
Other Materials
Application
Wood Building Systems
Author
Voulpiotis, Konstantinos
Köhler, Jochen
Jockwer, Robert
Frangi, Andrea
Organization
ETH Zurich
National Technical University of Norway
Chalmers University of Technology
Publisher
Elsevier
Year of Publication
2021
Country of Publication
Switzerland
Norway
Sweden
Format
Journal Article
Material
Other Materials
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Robustness
Tall Timber Buildings
Disproportionate Collapse
Reliability
System Effects
Language
English
Research Status
Complete
Series
Engineering Structures
Summary
With the ever-increasing popularity of engineered wood products, larger and more complex structures made of timber have been built, such as new tall timber buildings of unprecedented height. Designing for structural robustness in tall timber buildings is still not well understood due the complex properties of timber and the difficulty in testing large assemblies, making the prediction of tall timber building behaviour under damage very difficult. This paper discusses briefly the existing state-of-the-art and suggests the next step in considering robustness holistically. Qualitatively, this is done by introducing the concept of scale, that is to consider robustness at multiple levels within a structure: in the whole structure, compartments, components, connections, connectors, and material. Additionally, considering both local and global exposures is key in coming up with a sound conceptual design. Quantitatively, the method to calculate the robustness index in a building is presented. A novel framework to quantify robustness and find the optimal structural solution is presented, based on the calculation of the scenario probability-weighted average robustness indices of various design options of a building. A case study example is also presented in the end.
Online Access
Free
Resource Link
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Non-Destructive Tests to Determine the Modulus of Elasticity of Wooden Boards

https://research.thinkwood.com/en/permalink/catalogue1140
Year of Publication
2012
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Fink, Gerhard
Kohler, Jochen
Organization
ETH Zurich
Year of Publication
2012
Country of Publication
Switzerland
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Spruce
Non-Destructive Tests
Tensile tests
Young's Modulus
Knots
Language
German
Research Status
Complete
Summary
At the institute of structural engineering at the ETH Zurich multiple of investigations are conducted to analyse the material properties of Norway spruce timber boards. The investigations are part of the research project “Influence of varying material properties on the load bearing capacity of glued laminated timber (glulam)”. The majority of the investigations are non-destructively. The investigations are taking place on 400 timber boards. On all specimens the moisture content, the density, the Eigenfrequency and the longitudinal ultrasonic runtime was investigated. Further all knots with a diameter larger then 10mm are measured. Thereby the position and the size of all the knots are documented. Subsequently on 200 selected boards non-destructive tensile test are performed to analyse the local young modulus. Herewith it was particularly focused on the investigation of the stiffness of areas having knots or knot clusters and areas without knots. The strains are measured with an optical coordinatemeasurement device. In the last part of the experimental investigation the deformation and failure behaviour of significant knot clusters is analysed. The strains are measured with digital image correlation. Focus of the entire experimental analysis was the investigation of the young modulus and the quantifications of its variability within timber members and between timber members. Within this study a database was produced to evaluate existing test methods for the estimation of the young modulus. Further, the results can be used as a basis for further investigations on the variability of structural timber.
Online Access
Free
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Remaining Load-Bearing Behaviour of Glued Laminated Timber Beams - Potential in Respect to Structural Robustness

https://research.thinkwood.com/en/permalink/catalogue494
Year of Publication
2014
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Fink, Gerhard
Frangi, Andrea
Kohler, Jochen
Year of Publication
2014
Country of Publication
Canada
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Load Bearing Capacity
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
In the paper presented here the remaining load bearing capacity and the associated deformation of GLT beams is investigated and its potential in respect to robustness is discussed.
Online Access
Free
Resource Link
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