Overview of load groups

Features of load groups

Load groups are an aid to building combinations - both manually and using the generator - and their use is entirely optional.
Once a combination is built using load groups, the link to the load group is lost – the combination is made up only of loadcases. Only loadcases and combinations are analyzed – load groups are not.
Each load group holds items of a single load type - e.g. “Dead” or “Live”...etc. - and can contain both multiple loadcases and other load groups
The fundamental load groups setting is the “Class” which is either “Inclusive” or “Exclusive”
- When “Inclusive” – all loadcases are added at once into a combination
- When “Exclusive” – loadcases are used one at a time in combinations. Thus for example, where an Exclusive load group contains four loadcases, the generator will produce four combinations for all required combinations which include the group’s load type (e.g. “Imposed”), each containing only one of the group’s four cases.

The load groups process

To make use of load groups you would proceed as follows:

Define Loadcases as normal
If required, create load groups from loadcases and/or other load groups
Create combinations by combining loadcases and/or load groups

The end result is loadcases and combinations (built up of factored loadcases). These are then run through analysis and design.

Create load groups

On the Load tab, click Load Groups.

The Loading dialog box opens on the Load Groups page. On this page, you can see all currently existing load groups.
Click Add.
Enter the Load Group Title.
In Class, select the desired load group class.
- Inclusive - all loadcases are added at once into a combination
- Exclusive – loadcases are used one at a time in combinations
Click the load group name in the left hand panel of the dialog to display the available loadcases.
Select each loadcase in turn to be included and click the right arrow button to copy it into the load group.

Note:
A load group can only contain items of one load type.
Click OK.

Tekla Structural Designer adds the new load group to the list of load groups.

Inclusive and exclusive load groups example

In this simplified example, loadcases will be arranged into inclusive and exclusive load groups. The resulting load groups will then be used to create some combinations.

You can work through the example yourself by creating the loadcases shown below.

Once the above loadcases have been specified, the procedure is as follows:

From the Load Groups tab, a Dead load group is added and set as Inclusive. From the available loadcases Dead 1, Dead 2, and Dead 3 are selected.
Next a Live load group is added and again set as Inclusive. From the available loadcases Live 1, Live 2, and Live 3 are selected.
Finally a Wind load group is added. From the available loadcases Wind 1, Wind 2, and Wind 3 are selected. Because there is a requirement for each of these loadcases to be placed in a separate combination the class is set as Exclusive.
From the Combinations tab, a Dead and Live combination is added. From the available loadcases the Self weight - excluding slabs and the Slab self weight loadcases are selected. From the same list the Dead load group and the Live load group are also selected. (Note that in the "Available" and "Included" lists load groups are shown in bold italics.)
Next a Dead and Wind combination is added. For this combination the self weight loadcases, the Dead load group and the Wind load group are selected.
The Loading dialog then has to be closed and reopened in order to create the required combinations from the load groups. Because the Wind load group was exclusive, three separate combinations have been created to cater for each of the group's three wind loadcases.
Once combinations have been created from load groups in this way, the load groups are replaced in the list of included loadcases by the loadcases themselves, (with appropriate factors according to load type).