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What is kdef (creep timber)?

The stiffness properties of timber depend on the timber type (solid, glued, …) and the climatic conditions (temperature, moisture variations). The effect is taken into account by the factor kdef.

According to Eurocode

  • Values for kdef are given in EN 1995-1-1 Table 3.2.
  • kdef is used to calculate the final mean values of the stiffness properties according to EN 1995-1-1 §2.4.1.
Design values Mean values Final mean values

    \[ E_d=\frac{E_m_e_a_n}{\gamma_m} \]

    \[ E_m_e_a_n \]

    \[ E_m_e_a_n_._f_i_n=\frac{E_m_e_a_n}{1+\Psi_2 k_d_e_f} \]

    \[ G_d=\frac{G_m_e_a_n}{\gamma_m} \]

    \[ G_m_e_a_n \]

    \[ G_m_e_a_n_._f_i_n=\frac{G_m_e_a_n}{1+\Psi_2 k_d_e_f} \]


In Diamonds

  • The values for kdef are implemented in the material library of Diamonds.

  • When you check the option ‘Take creep into account’ after clicking , the final mean value for Young’s modulus E_m_e_a_n_._f_i_n will be used. \Psi_2 is set equal to 1.


Note: PowerFrame cannot take kdef into account. Only Diamonds can.

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