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7 records – page 1 of 1.

Analysis of Shear Transfer and Gap Opening in Timber–Concrete Composite Members with Notched Connections

https://research.thinkwood.com/en/permalink/catalogue1399
Year of Publication
2017
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
Author
Boccadoro, Lorenzo
Steiger, René
Zweidler, Simon
Frangi, Andrea
Publisher
Springer Netherlands
Year of Publication
2017
Country of Publication
Netherlands
Format
Journal Article
Material
Timber-Concrete Composite
Topic
Connections
Mechanical Properties
Keywords
Notched Connections
Analytical Model
Shear Stress
Failure
Language
English
Research Status
Complete
Series
Materials and Structures
ISSN
1871-6873
Summary
In timber–concrete composite members with notched connections, the notches act as the shear connections between the timber and the concrete part, and have to carry the shear flow necessary for composite action. The shear transfer through the notches generates shear and tensile stresses in both parts of the composite member, which may lead to brittle failure and to an abrupt collapse of the structure. Although simplified design formulas already exist, some structural aspects are still not clear, and a reliable design model is missing. This paper summarizes current design approaches and presents analytical models to understand the shear-carrying mechanism, to estimate the shear stresses acting in the timber and concrete, and to predict failure. The analysis concentrates on three problems: the shearing-off failure of the timber close to the notch, the shear failure of the concrete, and the influence of the shear flow on the gap opening between the timber and concrete. Parts of the model calculations could be compared to experimental observations. The conclusions of this paper contribute to improving current design approaches.
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Comparison of Bending Stiffness of Cross-Laminated Solid Timber Derived by Modal Analysis of Full Panels and by Bending Tests of Strip-Shaped Specimens

https://research.thinkwood.com/en/permalink/catalogue445
Year of Publication
2012
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Steiger, René
Gülzow, Arne
Czaderski, Christoph
Howald, Martin
Niemz, Peter
Publisher
Springer-Verlag
Year of Publication
2012
Country of Publication
Germany
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Elastic Properties
Stiffness Properties
Bending Test
Bending Stiffness
Panels
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
ISSN
1436-736X
Summary
The design of cross-laminated solid timber (CLT) as load-bearing plates is mainly governed by serviceability criterions like maximal deflection and susceptibility to vibration. Hence, predicting the respective behavior of such plates requires accurate information about their elastic properties. According to product standards, the bending stiffness of CLT has to be assessed from 4-point bending tests of strip-shaped specimens, cut from the CLT panels. By comparing elastic properties of CLT derived by means of modal analysis of full panels with the results of bending tests on 100 mm and 300 mm wide strip-shaped specimens it is shown, that by testing single 100 mm wide strip-shaped specimens bending stiffness of full panels cannot be assessed correctly, whereas single 300 mm wide strips or averages of 5 to 6 100 mm wide strip-shaped specimens lead to acceptable results. Hence, strip-shaped specimens should only be used in the course of factory quality control or when assessing the bending stiffness of parts of CLT panels used as beam-like load-bearing elements but not to derive bending stiffness of gross CLT panels. Verification by carrying out static bending tests of gross CLT panels under different loading situations showed that alternatively to tests on strip-shaped specimens or estimations with the compound theory, the overall stiffness properties of CLT can be derived directly by a modal analysis of full-size panels.
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Design of Timber Members Subjected to Axial Compression or Combined Axial Compression and Bending Based on 2nd Order Theory

https://research.thinkwood.com/en/permalink/catalogue115
Year of Publication
2015
Topic
Design and Systems
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Author
Frangi, Andrea
Steiger, René
Theiler, Matthias
Organization
International Network on Timber Engineering Research (INTER)
Year of Publication
2015
Country of Publication
Germany
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Topic
Design and Systems
Mechanical Properties
Keywords
Bending
Buckling
Codes
Compression
Deformation
Monte Carlo
Simulation
Structural
Testing
Language
English
Conference
INTER 2015
Research Status
Complete
Notes
August 24-27, 2015, Sibenik, Croatia
Summary
The paper examines the behaviour of structural timber members subjected to axial compression or combined axial compression and bending. Based on experimental and numerical investigations, the accuracy of the existing approach in Eurocode 5 for the design of timber members subjected to axial compression or combined axial compression and bending is assessed and modifications are suggested. By means of extensive experimental investigations, a data base was created for the validation of calculation models and for the assessment of design concepts. In order to assess the behaviour of timber members subjected to axial compression or combined axial compression and bending, strain-based calculation models were developed. The investigations indicate that the existing approach of Eurocode 5 based on 2nd order analysis can lead to an overestimation of the load-bearing capacity. Hence, a modified design approach was developed which agrees with the results of the Monte Carlo simulations very well and thus ensures a safe and economical design of timber members subjected to compression or combined compression and bending.
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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.
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Non Destructive Evaluation of Elastic Material Properties of Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2315
Year of Publication
2008
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems

Performance of Self-Tapping Screws and Threaded Steel Rods in Shear Reinforcement of Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue1628
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Jockwer, Robert
Steiger, René
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Connections
Mechanical Properties
Keywords
Norway Spruce
Reinforcement
Self-Tapping Screws
Threaded Steel Rod
Stiffness
Strength
Load Carrying Capacity
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 2813-2822
Summary
Norway spruce glulam beams with artificial horizontal slits of different length and depth were reinforced using self-tapping screws and threaded steel rods in order to restore their load-carrying capacity and stiffness. The study aimed at evaluating the effects of strength and stiffness of the applied reinforcing elements on the load-carrying capacity and stiffness of glulam beams after retrofitting. Self-tapping screws and threaded steel rods of different diameter have been evaluated in the study and different numbers of reinforcing elements have been applied. Shear failure of the beams with artificial slits of different depth was provoked in loading cycles with stepwise installation of the reinforcing elements in the beam parts failed in the preceding test. The reinforcing effect of the tested self-tapping screws and threaded steel rods reached and partly exceeded the estimated level calculated with selected analytical models. Unfavourable structural behaviour arose in some cases from crack opening during installation of the rods causing a very low initial stiffness. Comparison of test results to calculations of stiffness and load-carrying capacity of the reinforced beams applying the -method, the shear analogy method and a truss model revealed that the -method and the shear analogy method provided the best estimates of strength / stiffness of the reinforced beams.
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Timber Trusses Made of European Beech LVL

https://research.thinkwood.com/en/permalink/catalogue1527
Year of Publication
2016
Topic
Connections
Design and Systems
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Application
Trusses
Author
Kobel, Peter
Frangi, Andrea
Steiger, René
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Trusses
Topic
Connections
Design and Systems
Mechanical Properties
Keywords
Europe
Beech
Dowel-Type Connections
Ductile Failure
Embedment Tests
Embedment Strength
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 667-674
Summary
This paper presents an experimental and analytical investigation on the application of laminated veneer lumber (LVL) made of European beech wood (fagus sylvatica L.) in timber truss structures. Particular focus is laid on developing improved design approaches for dowel-type connections and on promoting ductile failure behaviour, as the connections in timber trusses are generally governing the performance of the whole structure. Embedment tests were carried out in order to assess the embedment strength values for beech LVL, which are necessary to design dowel-type connections. The results showed higher values for beech LVL, as compared to estimations using existing formulas from design codes. A series of tensile connection tests showed that, using cross-layered beech LVL, ductile dowel-type connections with high load-carrying capacities can be designed, given that premature brittle failures are prevented. Lastly, tests on full truss structures confirmed that the favourable behaviour of dowel-type connections in cross-layered beech LVL can be implemented in truss systems, improving the global behaviour of the whole structural element.
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7 records – page 1 of 1.