Performance of Post-Tensioned Timber and Engineered Timber Adhesives with Fire Exposure
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Performance of Post-Tensioned Timber and Engineered Timber Adhesives with Fire Exposure by Hailey Quiquero A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Master of Applied Science in Civil Engineering Ottawa, Ontario © 2018, Hailey Quiquero Abstract An increased environmental conscientiousness in society and the abundance of timber in Canada has inevitably lead to the desire for more timber construction. In order to increase the opportunity for timber products in construction, novel building systems such as Post- Tensioned (PT) timber are required. A model was developed and validated in Abaqus to investigate the ability of FEM software packages to model PT timber in fire conditions. The numerical model showed highly promising results for demonstrating the loading and failure behaviour of PT timber beams. Beam failure times were modelled within 5%, and load-deflection behaviour and failure mechanisms were accurately demonstrated. Additionally, the performance of timber adhesives after fire damage was examined after previous research suggested further investigation was required. Based on the experimental results, additional zero-strength layer thicknesses were estimated conservatively to be 23 mm beyond the char front (95th percentile) to account for the loss of strength (subject to various limitations). It is recommended that a new standardized test be developed for timber adhesives which quantifies the performance beyond the char layer in burnt engineered timber so that individual adhesives may be evaluated. ii Acknowledgements First and foremost, I must express my utmost appreciation and thanks to my supervisor, Dr. John Gales for his tireless assistance and guidance throughout my time working with him. My research began with John as an undergraduate student and his countless hours of work and support have helped me grow into the researcher I am today. His encouragement always pushed me to new limits and his support of all students is inspiring. I would also like to express my appreciation for the time and suggestions from Ata Khan, David Lau, Nourredine Bénichou and Magdi Mohareb, which elevated my thesis to the best work I could produce. I also must acknowledge many of my colleagues at Carleton who I have worked with throughout the degree including Lauren Folk, Claudia Gaudreault, Seth Gatien, Arlin Otto, Josh Woods and Matthew Smith. I thank you for the endless amounts of advice, learning, travelling, laughter and conferences attended. I must especially thank Matthew Smith for guiding me in learning about consultancy and how my research could benefit practitioners. I would also like to thank the Carleton University Civil lab staff, especially Stanley Conley and Jason Arnott, for their help and guidance with running my experiments. I would also like to thank Dr. Anthony Abu for graciously accepting me into his team at the University of Canterbury and teaching me not only about PT timber and numerical modelling, but also invaluable lessons on life as a graduate student and where best to travel in NZ. Furthermore, thank you to Dr. Peter Moss and Dr. Andy Buchanan for their guidance. I will forever appreciate and look back fondly on my time at UC. iii Additionally, I give my thanks to my colleagues at UC, especially Elizabeth North and Alex Meredith, for welcoming me into their lives as I endeavored to feel at home in NZ. Finally, I must acknowledge the abundance of support I have received from my loved ones. To Chad, thank you for supporting me in this post-graduate endeavor and especially in spending several months abroad, coming to visit and keeping me sane through countless challenges and breakthroughs. To my parents Mario and Susan and my sister Lauren, thank you for your continuous support and for making me feel that I can accomplish anything I set my mind to. I would also like to acknowledge Carleton University, NSERC (CGS and MSFSS) and the OGS program for supporting me throughout my degree. iv Table of Contents Abstract................................................................................................................................ii Acknowledgements ............................................................................................................iii Table of Contents.................................................................................................................v List of Tables.....................................................................................................................xii List of Figures...................................................................................................................xiv Statement of Co-Authorship and Scholarly Outputs .......................................................xxv Chapter 1: Introduction........................................................................................................1 1.1 Structural Fire Engineering........................................................................................1 1.1.1 Performance-Based Fire Design.........................................................................2 1.1.2 Structural Fire Engineering in Canada ...............................................................3 1.1.3 Building and Innovating with Timber ................................................................4 1.2 Motivation and Research Objectives.........................................................................5 1.3 Research Scope and Thesis Outline...........................................................................6 1.3.1 Chapter 2 – Background and Literature Review ................................................7 1.3.2 Chapter 3 – Finite Element Modelling of Post-Tensioned Timber Beams ........7 1.3.3 Chapter 4 – Timber Adhesive Performance after Fire Damage .........................8 1.3.4 Chapter 5 – Conclusions and Recommendations ...............................................8 1.3.5 Appendices .........................................................................................................9 Chapter 2: Background and Literature Review .................................................................10 v 2.1 Timber Structures in Fire.........................................................................................10 2.1.1 Engineered Timber Products ............................................................................12 2.1.2 Standard Fire Testing........................................................................................13 2.1.3 Charring Behaviour of Timber .........................................................................14 2.1.4 Timber Adhesive Standards..............................................................................18 2.1.5 Research on Timber Adhesive Fire Performance.............................................20 2.2 Numerical Modelling of Timber in Fire Conditions................................................22 2.2.1 Past Numerical Modelling of Timber...............................................................29 2.3 Post-Tensioned Timber............................................................................................32 2.3.1 Post-Tensioned Timber Beams.........................................................................33 2.3.2 Past Experiments on PT Timber in Fire ...........................................................34 2.3.3 Existing and Proposed PT Timber Structures...................................................38 2.4 Conclusions..............................................................................................................40 Chapter 3: Finite Element Modelling of Post-Tensioned Timber Beams .........................42 3.1 Introduction..............................................................................................................42 3.2 Research Objectives and Approach .........................................................................44 3.3 Software Selection...................................................................................................46 3.3.1 Abaqus ..............................................................................................................46 3.3.2 ANSYS .............................................................................................................49 3.3.3 LS DYNA .........................................................................................................49 vi 3.3.4 DIANA .............................................................................................................50 3.3.5 SAFIR...............................................................................................................50 3.3.6 Vulcan...............................................................................................................51 3.4 Ambient Numerical Modelling................................................................................51 3.4.1 Model Setup......................................................................................................51 3.4.2 Material Models................................................................................................59 3.4.3 Mesh Study .......................................................................................................77 3.4.4 Comparison of Results to Experiments ............................................................80 3.5 Heat Transfer Modelling..........................................................................................90