Fire Behavior of Cross-Laminated Timber (CLT) Slabs: Two-Way Action

  • Nicholas DoyleEmail author
  • Richard Emberley
  • José L. Torero
Conference paper


Two-way action is often stated to be a major benefit of cross-laminated timber; however, it is seldom considered when designing tall timber buildings. A research project has been carried out to investigate this inconsistency with the objective of understanding the significance of cross-laminated timber slabs acting as two-way members. This objective was met through semi-parametric analytical modeling carried out in conjunction with bending tests on small-scale, three-layer cross-laminated timber samples. The fire variable was reduced to the process of charring which was simulated by varying the number and thickness of layers. Two-way and one-way tests were run in parallel to allow direct comparison between strain, stiffness, failure modes, and load-carrying capacity. Results of the modeling and experiments showed that, for standard panel lay-ups, two-way load transfer is enhanced by the charring process. The load-carrying capacity of charred two-way slabs was improved by as much as 50 % over the one-way equivalent. In instances, the elastic stiffness was more than doubled. It was concluded that utilizing the two-way ability of cross-laminated timber could lead to more optimal use of the material, and assuming one-way behavior in all instances may be overconservative.


Cross-laminated timber (CLT) Tall timber building Two-way 



Area (m2)


Width of a CLT layer (m)


Depth from centroid of CLT layer to centroid of CLT panel (m)


Depth of char (mm)


Elastic modulus (MPa)


Effective elastic modulus for CLT panel lay-up (MPa)


Elastic stiffness (N/m)


Span of a member


Thickness of CLT layer (m)


Uniformly distributed load (N/m)


Centroid depth for CLT lay-up (m)

\( \overline{z} \)

Centroid location of individual CLT layer (m)

Greek Symbols


Charring rate (m/s)


Time (s)



Initial state of the variable


ith layer of CLT panel (from bottom)


jth layer of CLT panel (from bottom)




Direction of CLT slab initially more stiff


Direction of CLT slab initially less stiff



The authors would like to thank Dr. Dilum Fernando of The University of Queensland for his technical advice and Dr. Henri Bailleres of DAFF for supplying the CLT samples used for this paper.


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Copyright information

© Springer Science+Business Media Singapore 2017

Authors and Affiliations

  • Nicholas Doyle
    • 1
    Email author
  • Richard Emberley
    • 1
  • José L. Torero
    • 1
  1. 1.The University of QueenslandSt. LuciaAustralia

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