9.4 Load Duration and Service Class

The moisture-dependent change in strength of the anisotropic material timber is determined by means of the load duration class (LDC) and the service class (SECL).

All actions that were selected for design in Window 1.3 Loads are listed. For combinations, the contained load cases are specified as well.

The load case descriptions make the classification easier.

This column shows the action types of the load cases as they were defined in RFEM or RSTAB during their creation. They form the basis for the default settings in the next column.

The designs require you to assign the loads and their superpositions to particular load duration classes. The classification of actions is described in [2] Table 2.1.

For load cases and result combinations, you can change the load duration using the list. For load combinations and Or result combinations, RF-/JOINTS performs the classification automatically, taking into account the respective leading action or the contained load cases.

The load duration class is required to determine the modification factor k_mod which affects the strength properties of the material (see [2] Table 3.1). The coefficients k_mod can be checked in the National Annex Settings dialog box and adjusted if necessary (see Figure 2.19).

The classification into service classes makes it possible to assign strength parameters in consideration of environmental conditions. The service classes are specified in [2] Section 2.3.1.3, for example.

By default, all members are assigned to the same service class. To classify objects into different service classes, select the Different check box. You can then use the button to open the following dialog box.

It allows you to individually classify the members into service classes. The buttons next to the text boxes facilitate the assignment. They have the following functions:

Table 9.4 Buttons in the Assign Members to Corresponding Service Classes dialog box

Button	Function
	Allows for graphical selection of members in RFEM/RSTAB work window
	Assigns all members to this service class
	Assigns all members not yet assigned to this service class