Managing diaphragm action in roof panels and slabs
Tekla Structural Designer forms diaphragms in every slab item of a parent slab when Diaphragm option is set to Rigid or Semi-rigid.
When a rigid diaphragm is specified, Tekla Structural Designer automatically applies nodal constraints to the associated slab nodes.
In turn, when a semi-rigid diaphragm is specified, Tekla Structural Designer creates a mesh of semi-rigid 2D elements within the slab.
Activate rigid diaphragm option within a slab
By default, Tekla Structural Designer automatically creates rigid diaphragm within slabs. If necessary, you can review and modify the setting for specific slabs as follows:
Activate semi-rigid diaphragm option within a slab
You can form semi-rigid diaphragms in both one-way and two-way spanning slabs. In addition, you can review and modify the diaphragm properties by selecting the slab within which they are located.
Activate semi-rigid diaphragm option within a roof panel
You can form semi-rigid diaphragms in roof panels as follows:
Adjust semi-rigid diaphragm flexibility
When the Diaphragm option is Semi-Rigid a Divide stiffness by value can be set in the slab item properties. The same value is applied to all slab items in the same slab.
The stiffness determined from the material properties and slab thickness is divided by this value in order to adjust semi-rigid diaphragm flexibility.
Adjust global semi-rigid mesh properties
When a semi-rigid mesh is created the 2D solver element shape (triangular or quad), the degree of mesh uniformity, and mesh type adopted are obtained from the Structure Properties. These parameters can be overridden for individual sub-models by setting different values in the respective Sub Model Properties.
Apply different semi-rigid mesh properties at different levels
If you need to apply different semi-rigid mesh parameters at a specific level, you can do so by creating sub models.
- Create a sub model.
- In the Structure tree, expand the Sub Models branch.
- Select the sub model that you created.
- In the Properties window, select the Override model's option.
- Adjust the semi-rigid mesh size, uniformity factor and type according to your needs.
Identify the nodes constrained by rigid diaphragms
In order to see which nodes are constrained by diaphragms, see the following instructions.
A solver view opens. The rigid and semi-rigid diaphragms are represented as different colored shaded planes.
- Must lie within, or be on the edge of, the shaded rigid diaphragm plane.
- Must be solid rather than hollow, or excluded.
Therefore, the following nodes are not constrained by a rigid diaphragm:
- Solid nodes that lie outside the shaded rigid diaphragm plane.
- Hollow, or excluded, nodes.
Exclude individual nodes from a rigid diaphragm
If necessary, you can exclude specific nodes from a rigid diaphragm. In order to do so, see the following instructions.
Exclude slab items from a diaphragm
By default, Tekla Structural Designer forms a rigid diaphragm in all the individual slab items within a slab. However, you can decide to exclude specific slab items. In order to do so, see the following instructions.