Open the Geometrical Imperfections dialog, using either method:
- Click Geometry menu > Additional Attributes > Geometrical Imperfections.
- Click .
This dialog lets you define initial geometrical imperfections. Geometrical imperfections can be assigned to single bars or to a group of coolinear bars (so-called superbars). Imperfections do not cause initial forces or structure stresses. Imperfections only change the structure geometry.
When using geometrical imperfections, remember:
- Imperfections are assigned only to bar elements
- Imperfections are assigned at the midpoint in the length of a single bar or coolinear bar group
- Imperfections change the geometry of a bar or a bar group; the change of geometry is modeled by a created chain of calculation elements that represent a deformed shape
- All results from structure calculations are displayed on a deformed structure (that is, the structure with geometrical imperfections considered). Nodal displacements are determined in relation to the initial geometry you defined.
The dialog has 3 parts:
- At the top, there are several buttons:
- - Adds a new type of geometrical imperfection (Definition of a new imperfection type).
- - Deletes a type of imperfection from the list.
- , , , and - Displays the list of active imperfections as: large icons, small icons, short list, and long list.
- - Deletes from the list, all types of imperfections that are not in the designed structure.
- - Opens the Label Manager dialog.
- A field that lists the active imperfection types
- At the bottom, the current selection field and standard buttons.
Similar to the dialog that defines other structure attributes, the process of defining a geometrical imperfection in a structure has 2 steps:
- Defining a geometrical imperfection type
If the list of imperfections is empty, or a new imperfection type is to be added to the list, click Definition of a new imperfection type:
- If none of the imperfection types is selected, clicking opens the dialog to define a new imperfection type. The fields are filled with the last imperfection definition (except for the LABEL field) or the default parameters are set.
- If an imperfection type is highlighted, clicking opens the dialog to define a new imperfecton type. All fields (except for the LABEL field) are filled using the highlighted type.
Also, you can open the dialog for defining a new imperfection type by double-clicking an element in the list of imperfections. The Imperfection definition dialog opens with all fields filled according to the imperfection type selected.
- Assigning imperfections to structure bars.
To delete an imperfection from the structure:
- Click on the active imperfection list,
- Select an object in the structure that you want to delete the imperfection from.
You cannot modify this type of imperfection; it is assigned the same way as the imperfection properties are to a structure element.
After an imperfection is assigned, its symbol is drawn on the graphical screen.
See also:
Calculation of initial deflection for imperfections according to Eurocode 3