Blog List

Friday, 16 September 2016

Reliability analysis and duration-of-load strength adjustment factor of the rolling shear strength of cross laminated timber

  • Frank Lam

  • Original article
    DOI: 10.1007/s10086-016-1577-0

    Cite this article as: 
    Li, Y. & Lam, F. J Wood Sci (2016). doi:10.1007/s10086-016-1577-0


    In this study, the duration-of-load effect on the rolling shear strength of cross laminated timber (CLT), with different cross-sectional layups (five-layer and three-layer), was evaluated. A stress-based damage accumulation model is chosen to evaluate the duration-of-load strength adjustment factor of the rolling shear strength of CLT. This model incorporates the established short-term rolling shear strength of material and predicts the time to failure under arbitrary loading history. The model has been calibrated and verified based on the test data from low cycle trapezoidal fatigue tests (damage accumulation tests) in the previous study. The long-term rolling shear behaviour of CLT can then be evaluated from this verified model. As the developed damage accumulation model is a probabilistic model, it can be incorporated into a time based reliability assessment of the CLT products, considering short-term, snow, and dead load only loading cases. The reliability analysis results and factors reflecting the duration-of-load effect on the rolling shear strength of CLT are compared and discussed. The characteristic of this modeling theory lies in that the verified model is also able to predict the duration-of-load behaviour of CLT products under arbitrary loading history, such as long-term dead load case; then, these predictions of time to failure from the damage accumulation model can elucidate duration of load by the stress ratio evaluation approach. The results suggest that the duration-of-load rolling shear strength adjustment factor for CLT is more severe than the general duration-of-load adjustment factor for lumber; this difference should be considered in the introduction of CLT into the building codes for engineered wood design.


    1. 1.
      FPInnovations (2011) Chapter 3 Structural design of cross-laminated timber elements, CLT handbook. Vancouver, British Columbia, Canada
    2. 2.
      Blass HJ, Görlacher R (2003) Brettsperrholz. Berechnungsgrundlagen (in German). Holzbau Kalender, Bruder, Karlsruhe, pp 580–598
    3. 3.
      Fellmoser P, Blass HJ (2004) Influence of RS modulus on strength and stiffness of structural bonded timber elements. CIB-W18/37-6-5, Edinburgh, UK
    4. 4.
      Jöbstl RA, Schickhofer G (2007) Comparative examination of creep of glulam and CLT slabs in bending. CIB-W18/40-12-3, Bled, Solvenia
    5. 5.
      Barrett JD, Foschi RO (1978) Duration of load and probability of failure in wood, part 1: modeling creep rupture. Can J Civil Eng 5(4):505–514CrossRef
    6. 6.
      Foschi RO, Barrett JD (1982) Load duration effects in western hemlock lumber. J Struct Div ASCE 108(7):1494–1510
    7. 7.
      Gerhards CC, Link CL (1987) A cumulative damage model to predict load duration characteristics of lumber. Wood Fiber Sci 19(2):147–164
    8. 8.
      Laufenberg TL, Palka LC, McNatt JD (1999) Creep and creep-rupture behaviour of wood-based structural panels. Project No. 15-65-M404, Forinteck Canada Corp, Madison, WI, USA
    9. 9.
      Madsen B (1992) Structural behaviour of timber. Timber Engineering Ltd., Vancouver
    10. 10.
      Li Y, Lam F (2016) Low cycle fatigue tests and damage accumulation models on the rolling shear strength of cross laminated timber. J Wood Sci 62:251–262CrossRef
    11. 11.
      Foschi RO (1989) Reliability-based design of wood structures. Structural Research Series Report No. 34, Dept. of Civil Engineering, University of British Columbia, Vancouver, Canada
    12. 12.
      Nielsen LF (1986) Wood as a cracked viscoelastic material. Part I: theory and applications, and part II: sensitivity and justification of a theory. In: Proceedings of international workshop on duration of load in lumber and wood products, Special Publ. No. SP-27, Forintek Canada Corp., Vancouver, British Columbia, pp 67–89
    13. 13.
      Foschi RO, Yao FZ (1986) Another look at the three duration of load models. In: Proceedings of IUFRO Wood Engineering Group meeting, Florence, Italy, paper 19-9-1
    14. 14.
      Bodig J, Jayne BA (1982) Mechanics of wood and wood composites. Van Nostrand Reinhold Company, New York, USA
    15. 15.
      EN 1995-1-1 (2004) Eurocode 5: design of timber structures. Part 1-1: general—common rules and rules for buildings. European Committee for Standardization, Brussels
    16. 16.
      Kreuzinger H (1999) Platten, Scheiben und Schalen—ein Berechnungsmodell für gängige Statikprogramme (in German). Bauen Mit Holz 1:34–39
    17. 17.
      Li Y (2015) Duration-of-load and size effects on the rolling shear strength of cross laminated timber. Ph.D. Thesis, University of British Columbia, Vancouver, Canada
    18. 18.
      CSA O86–09 (2009) Engineering design in wood. Canadian Standard Association, Mississauga, Outario, Canada

    For further details log on website :

    No comments:

    Post a Comment

    Advantages and Disadvantages of Fasting for Runners

    Author BY   ANDREA CESPEDES  Food is fuel, especially for serious runners who need a lot of energy. It may seem counterintuiti...