STAAD.Pro Help

Auto Load Combination dialog

Used to automatically create load combinations based on code-specified combination rules and primary load type selections.

In order to use this feature, one or more primary load cases must be created with a load type defined. A load type can be assigned to a primary load case either at the time when the load is being created or later.

Opens when the Automatic Combinations > Automatic Load Combinations tool is selected in the Load Generation group on the Loading ribbon tab.

Note: If no load cases have yet been defined for the model, a warning message is displayed over the dialog and the parameters are inactive. Primary load cases are defined using the Create Primary Load Case dialog.
Select Load Combination Code
The load types available include the following:
  • ACI
  • AISC
  • UBC
  • IBC
  • British
  • NBCC 1995
  • Indian Code
  • SNiP
  • NBC 2005
  • IBC 2012
Note: Any Load Rule sets you have added or edited in the Edit Load Rules for Auto Load Combination Generator dialog are also available here.
Select Load Combination Category Select the load combination category as specified in the selected load combination code. Refer to the selected code for details.
Generate Loads Click to create all the load combinations. The generated load combinations, with their associated load factors, are shown in the Selected Load Combinations list on the right-hand side.
Discarded Load Combinations Any load combinations which are generated can be removed from the final load combination. These will be listed here.
list operators
Click this button… to…
> Add the selected primary load case to the Selected Load Combinations list
>> Add all primary load cases to the Selected Load Combinations list.
<< Remove all entries in the Selected Load Combinations list, load combination is placed in the Discarded Load Combinations list.
< Remove the selected entry from the Selected Load Combinations list.
Selected Load Combinations list All load combinations which will be added to the input file are listed here.
Create Repeat Load Cases Select this option to create primary load cases for all the load case combinations in the Selected Load Combinations list using the Repeat Load Command, rather than combined results using Load Combinations.

See GS. Load Types in STAAD.Pro for additional information on using Repeat loads versus Load Combinations.

Include Notional Load? Select this option to include Notional Load cases in the generated combinations when the Create Repeat Load Cases option is selected, if they are present in the input file.

Automatically Generated Load Combinations in the STAAD input file

In the STAAD.Pro Input File, the generated load combinations look like the following:

2 UNI GY -2.5
2 FX 10
LOAD COMB 3 Generated AISC 1
1 1.6
LOAD COMB 4 Generated AISC 2
1 1.4
LOAD COMB 5 Generated AISC 3
1 1.7 2 0.8
LOAD COMB 6 Manual
1 1.7 2 -1.2

The syntax Generated xxx n, where xxx is the design code name (AISC, BOCA, etc.) and n is the index in the series of load combinations generated for a specific code, are interpreted by STAAD.Pro.  Deleting any of the aforementioned keywords will break the program’s ability to read back in the generated load combinations.

The following are some important caveats to keep in mind when using the automatic load combination generator:

  • If the automatically generated load combinations are edited (or deleted) from the STAAD input file, they will be reflected in the graphical interface as well.
  • The load combination numbers (i.e. LOAD COMB n GENERATED AISC 1) can also be edited from the input file.
  • Deleting the keyword GENERATED code index will remove that particular load combination from the automatically generated list. It will not remove the load combination.
  • The factors assigned to the primary load cases in a generated load combination cannot be changed in the graphical interface using the Combine button from the Loads dialog box.