The serviceability configuration is divided into several tabs that clearly structure the specifications for the individual designs.
Members
In the Members tab of the 'Serviceability Configuration' dialog, you define the limit values that apply to the deformations of members and member sets.
Serviceability Limit Values (Deflections) according to 7.2
There are different design situation types for serviceability limit state designs (see chapter Design Situations of the RFEM manual). When designing according to EN 1999-1-1, a distinction is made between the characteristic, the frequent, and the quasi-permanent combination. For each combination type, you can define specific limit values for deflections, which apply to the directions of the member axes, respectively.
In principle, the limit values of deformations are related to the lengths of the components: The longer a member is, the larger the permissible deflections. In the list next to the 'Definition type', you can select the form in which you want to define the limit value.
- Relative value: The limit value is defined in relation to the length of the member or member set.
- Absolute value: The value of the maximum deflection is defined directly.
- Sum of relative and absolute value: The limit value is the sum of 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 conditions of the component – 'beam' supported on both sides or 'cantilever beam' supported on one side – different deflection limit values are usually relevant. The type present for a specific segment is automatically determined based on the assigned design supports: A segment with design supports on both sides or without a design support is classified as a beam, a segment with a design support on one side as a cantilever beam. The design supports can be defined in the Design Supports and Deflection tab of the members and member sets.
If necessary, adjust the default limit values for the deformation analyses of the objects.
If a precamber (pre-deformation of the component during installation) is to be considered in the deformation analysis, you can specify this precamber in the properties of the member or member set (see chapter Design Supports and Deflection). There, you can also specify whether the maximum displacements refer to the displaced segment ends or the undeformed initial system.
Vibration
The 'Vibration' category allows you to easily check the deformation for the vibration analysis with reference to a vibration amplitude. For this design, all design situations to which the type SLS - Vibration is assigned in the Design Situations table are considered. It is assumed that these are corresponding load combinations or result combinations that contain the maximum values of the vibration amplitudes in the form of deflections. These are compared with the limit value in the respective axis direction.
Consider Precamber in the Following Design Situations
Activate the check boxes for the design situations in which the precamber is to be considered.
Surfaces
In the Surfaces tab of the 'Serviceability Configuration' dialog, you define the limit values that apply to the deformations of surfaces.
As for the Members, there are different design situation types for serviceability limit state designs. For each combination type, you can define specific limit values for deflections. They are related to the lengths of the components. The list next to the 'Definition type' contains several options for defining a limit value (see image Define Deformation Reference):
- Relative value: The limit value is defined in relation to the length of the surface.
- Absolute value: The value of the maximum deflection is defined directly.
- Sum of relative and absolute value: The limit value is the sum of 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 conditions of the component – surface supported on both sides or cantilever surface supported on one side – different deflection limit values 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 specify how the reference length is to be determined.
If necessary, adjust the default limit values for the deformation analyses of the objects.