Design of post-tensioned timber beams for fire resistance (2012)

Type of Content
Conference Contributions - PublishedPublisher
University of Canterbury. Civil and Natural Resources EngineeringCollections
Abstract
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 post-tensioned 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.
Citation
Spellman, P.M., Abu, A.K., Carradine, D.M., Moss, P.J., Buchanan, A.H. (2012) Design of post-tensioned timber beams for fire resistance. Zurich, Switzerland: 7th International Conference on Structures in Fire (SiF), 6-8 Jun 2012. SiF2012, 317-326.This citation is automatically generated and may be unreliable. Use as a guide only.
Keywords
structural fire engineering; fire engineering; timber structures; post-tensioned timber; fire performance; furnace test; designANZSRC Fields of Research
40 - Engineering::4005 - Civil engineering::400504 - Construction engineering40 - Engineering::4005 - Civil engineering::400510 - Structural engineering
40 - Engineering::4016 - Materials engineering::401610 - Timber, pulp and paper
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