In the Surfaces tab of the 'Serviceability Configuration' dialog, you define the limit values that apply for the deformations of surfaces.
As for the members, there are different design situation types for serviceability limit state design, which vary depending on the design standard. For each combination type, you can define specific limit values for the deflections. They are related to the lengths of the structural components.
The list next to the 'Definition type' contains several options for the form in which a limit value can be defined (see image Specify reference of deformation):
- Relative value: The limit value is defined in relation to the length of the surface.
- Absolute value: The value of the maximum deflection is specified directly.
- Sum of relative and absolute value: The limit value adds up from the relative value and the absolute value.
- Min. of relative and absolute value: The smaller value of the relative or absolute value applies as the limit value.
- Max. of relative and absolute value: The larger value of the relative or absolute value applies as the limit value.
Depending on the support of the structural component – surface supported on both sides or cantilever surface supported on one side – different limit values of the deflection are usually relevant. This support is to be defined as the 'Surface type' in the properties of the surface or the surface set in the Deflection tab. There you can also specify whether the maximum displacements refer to the undeformed system, a deformed reference plane, or a parallel surface, and define how the reference length is to be determined.
If necessary, adjust the preset limit values for the deformation analyses of the objects.