The strength properties of timber depend on
- the timber type (solid, glued, …)
- the load duration time (dead load is always present, wind loads are present for a shorter time, creep)
- and the climatic conditions (temperature, moisture variations).
The effect of these three parameter on the strength properties, is taken into account by the factor kmod.
According to Eurocode
- Values for kmod can be found in EN 1995-1-1 Table 3.1.
- kmod will adjust the material properties in the design of timber structures.
- The values for kmod are implemented in the material library of Diamonds.
- The service class (also called ‘Climate class’) to determine the value of kmod, can be imposed in the Load group dialog .
- Where a load combination consists of actions belonging to different load duration classes, the value of kmod should correspond to the action with the shortest duration (EN 1995-1-1 § 3.1.3).
For example: for a combination of dead load and medium term load, a value of kmod corresponding with the medium-term load should be used.
Note: it is not possible to impose a climate class in PowerFrame. Each timber-quality has one kmod assigned, which will be used for all combinations. The value for kmod can be viewed/changed with Edit > Material library.