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Design of Post-Tensioned Timber Beams for Fire Resistance

https://research.thinkwood.com/en/permalink/catalogue4
Year of Publication
2012
Topic
Design and Systems
Fire
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Buchanan, Andrew
Abu, Anthony
Carradine, David
Moss, Peter
Spellman, Phillip
Year of Publication
2012
Country of Publication
Switzerland
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Design and Systems
Fire
Keywords
Full Scale
Furnace Tests
Post-Tensioned
Box Beams
Vertical Loads
Failure
Language
English
Conference
International Conference on Structures in Fire
Research Status
Complete
Notes
June 6-8, 2012, Zurich, Switzerland
Summary
This paper describes a series of three full-scale furnace tests on post-tensioned LVL box beams loaded with vertical loads, and presents a proposed fire design method for post-tensioned timber members. The design method is adapted from the calculation methods given in Eurocode 5 and NZS:3603 which includes the effects of changing geometry and several failure mechanisms specific to posttensioned timber. The design procedures include an estimation of the heating of the tendons within the timber cavities, and relaxation of post-tensioning forces. Additionally, comparisons of the designs and assumptions used in the proposed fire design method and the results of the full-scale furnace tests are made. The experimental investigation and development of a design method have shown several areas which need to be addressed. It is important to calculate shear stresses in the timber section, as shear is much more likely to govern compared to solid timber. The investigation has shown that whilst tensile failures are less likely to govern the fire design of post-tensioned timber members, due to the axial compression of the post-tensioning, tensile stresses must still be calculated due to the changing centroid of the members as the fire progresses. Research has also highlighted the importance of monitoring additional deflections and moments caused by the high level of axial loads.
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The Fire Performance of Post-Tensioned Timber Beams

https://research.thinkwood.com/en/permalink/catalogue159
Year of Publication
2012
Topic
Fire
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Spellman, Phillip
Organization
University of Canterbury
Year of Publication
2012
Country of Publication
New Zealand
Format
Thesis
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Fire
Keywords
Failure Mechanisms
Full Scale
Post-Tensioning
Steel Tendons
Fire Resistance
Box Beams
Language
English
Research Status
Complete
Summary
The focus of this research was to investigate the fire performance of post-tensioned timber beams. This was completed through a series of full-scale furnace tests, and the development of a fire resistance design method. Previous research has focused on the seismic performance and gravity frame performance of post-tensioned timber, both of which yielded promising results. There is however a commonly perceived increase in fire risk with timber building, particularly multi-storey timber buildings, and the fire performance of post-tensioned timber had not previously been investigated.
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Free
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Literature Survey on Nail-Laminated Timber and Box Beam

https://research.thinkwood.com/en/permalink/catalogue1210
Year of Publication
2017
Topic
Design and Systems
Market and Adoption
Material
NLT (Nail-Laminated Timber)
Application
Beams
Author
Ni, Chun
Karacabeyli, Erol
Organization
FPInnovations
Year of Publication
2017
Country of Publication
Canada
Format
Report
Material
NLT (Nail-Laminated Timber)
Application
Beams
Topic
Design and Systems
Market and Adoption
Keywords
Box Beams
Mechanical Joints
CSA 086
Language
English
Research Status
Complete
Summary
Nail-Laminated Timber (NLT) and box beam are efficient and economical engineered wood products. Although NLT has been used in North America for more than a century, only in recent years it has gained renewed interests as they have been seen as the most economical panel products used in mass timber buildings. Box beams, on the other hand, are lightweight and generally possess higher strength and stiffness than comparable-sized solid timber and are more efficient than solid timber large spans and loads. In this report, existing design provisions and their limitations for the design and construction of NLT in box beam in Canadian standards are reviewed. For NLT, there is a general lack of information related to manufacturing, design and construction to ensure consistent manufacturing and installation practices. Therefore, it is difficult to research and document with confidence the full range of performance that can be achieved with NLT. It is therefore recommended that a North American product standard and design information on structural performance, floor vibration, fire resistance, acoustic performance, and construction risk mitigation measures (e.g. moisture and fire) be developed. In CSA 086, design methods are limited to box beams with flanges and webs bonded with glue. As the flanges and webs of a box beam can be assembled by either glue or mechanical fasteners, it is recommended that design provisions for box beam with mechanical joints be also developed. With the information in Eurocode 5 and relevant supporting research papers, it is ready to be implemented.
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Shear Strength of LVL Box Beams in Fire Conditions

https://research.thinkwood.com/en/permalink/catalogue540
Year of Publication
2014
Topic
Fire
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Costello, Reuben
Abu, Anthony
Moss, Peter
Buchanan, Andrew
Year of Publication
2014
Country of Publication
Canada
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Fire
Mechanical Properties
Keywords
Box Beams
Post-Tensioned
Fire Performance
Shear Strength
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
This paper outlines a series of experimental tests of LVL box beams designed to fail in shear. Some beams utilised post-tensioning systems to increase the flexural strength and decrease deflection. Fire conditions were simulated using either an ISO 834 furnace test or by mechanically reducing the section dimensions on three-sides of the beam to replicate charring. Comparisons with a simplified calculation method for the fire performance of post-tensioned timber box beams are made and discussed. This paper gives special focus to the shear performance of LVL box beams because previous research had identified that the inclusion of post-tensioning may increase the likelihood of shear failure occurring in LVL box beams, especially in fire conditions.
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Free
Resource Link
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