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Modelling the long-term strength of timber columns

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This paper studies the influence of the used creep function, and the duration of the experimental sustained loading from which the creep function was derived, in modelling the long-term buckling strength of timber columns. The sensitivity of this buckling strength to creep and initial deflection is numerically studied using an energy approach that takes into account the initial deflection. Various creep functions — power laws as well as exponential laws — derived from bending experiments of different durations are used for the numerical simulation. The crucial need for experimental results issued from very long load period experiments is identified. Such experiments may lead to a more credible creep analysis of timber structures.

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radius of giration


stress level

EL :

effective MOE

E0 :

instantaneous MOE


inertia moment

Kσ,K′σ :

geometrical matrices


length of beam or column

Lf :

effective length

Ncr :

axial force, buckling load


elastic strain energy


external forces work


time variable


moisture content (m.c.)


total deflection

vc, ve, v0 :

creep, instantaneous elastic and initial deflections respectively


time function

ɛ, ɛe, ɛ0 :

total, instantaneous and initial strains respectively


twist rotation


creep coefficient or fractional creep or relative creep


shape function


load factor


longitudinal shortening


total potential energy


creep factor


relaxation time


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Ayina, O., Morlier, P., Reynouard, J. et al. Modelling the long-term strength of timber columns. Wood Sci.Technol. 30, 491–503 (1996). https://doi.org/10.1007/BF00244443

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  • Timber
  • Period Experiment
  • Material Processing
  • Energy Approach
  • Timber Structure