How to create and use a custom cross-section
IDEA StatiCa offers the possibility to create your own custom cross-section, analyze its properties, and use it in your project as a part of a joint. The procedure is the following:
1. Within a project you have already created, click on the Design tab in the upper ribbon. In the list of Members, choose the one you wish to change the cross-section to.
2. Click on the “plus” button to open the Cross-section navigator and from the Welded, Composed tab, select the General steel cross-section.
3. A new window opens which is the General cross-section editor, where we will create our custom cross-section. Click on the New icon and select General plate. Of course, you can use any of the cross-sections from the library and combine them to create anything that you want. Click OK to insert this plate in the editor.
Note about insertion points
In order to align and connect plates or cross-sections, the editor creates insertion points with an index number (1, 2, 3...) in all corners of an element. We can use these numbers to place the element to an exact position in the following principle: except the first element, all the rest have a Master component (the reference element). When a second element is inserted, we need to define 3 things: the Master component, which of the points of the master component will be used as the Master point, and which of the points of the second element will be used as Insert point.
4. Repeat Step 3 to insert a second plate (10x100 mm), and give it the same properties, as the following image shows. The plate will be aligned to the left upper corner of the Master plate.
5. Repeat Step 3 to insert the third plate (10x130 mm) and give it the same properties, as the following image shows. The plate will be aligned to the upper centre of the Master plate.
If you want to see the calculated properties of a cross-section, click on the
menu on the left. Click OK to close the editor and insert the cross-section into your model.
Please pay attention to the following aspects:
The general cross-section editor provides the calculation of the geometrical properties of the cross-section using numerical methods. Nevertheless, the mesh which can be displayed here does not correspond to the mesh created during the stress-strain analysis of the loaded connection. Therefore, some results of stress provided by the General cross-section editor may differ from the ones from the STR analysis of the connection.
Also, please always check the continuity of the composed cross-section to see that all the plates are welded together. To do that, go to Materials, select the created general cross-section, pull the vertical dividing border to the left and display the drawing of the general cross-section. Look for the short thick blue lines connecting the individual plates. These constraints represent the connection of the corresponding nodes of the connection mesh and can be thought of as butt welds. In order for these constraints to be created, the plates must be positioned so that there is an intersection of their normal planes.
If the short lines are not present, the plates are not connected and it is necessary to adjust their position within the cross-section.