Bracings are structural elements which provide stability and resistance to lateral loads. They may be steel members, but they can also have a concrete “core”. In braced constructions, beams and columns are designed under vertical loads only, assuming that the bracing system carries all lateral loads.
In Advance Design, bracings may be defined as a "bar"-type element. This type of element has by default free rotational DOFs(Degrees of Freedom) at both ends (pinned):
Figure 1 – Bar-type element end releases
It is important to point out that this type of linear element should not be imposed as a Supporting element for snow and wind loads since it only takes axial, and not bending forces. If done so, the load distribution will not be not correct.
Figure 2 – Supporting element option unchecked
The "Supporting element" option refers to structural elements on which the loaded pannels distribute the load from wind and snow actions (e.g. façade pannels which are fixed to the columns or purlins). In Figure 3 it is easy to see how the lateral loads from wind actions are distributed to the supporting elements of the structure (columns):
Figure 3 – Load distribution to the "Supporting element"
Note: The users are advised to make sure that the bracings do not intersect with the mesh points of the supporting elements. This would lead to incorrect force distribution among the elements:
Figure 4 – Suggested mesh points distribution
The positive effect of bracings in the behavior of the structure is easyly seen when comparing the displacements results from lateral loads of the same structure with and without bracings.
Figure 5 – Displacements of the structure with no bracings
Figure 6 – Displacements of the structure with bracings