To create a load combination
To create a combination of existing load cases, use the following procedure.

On the
Model ribbon tab, select the
Load Combination tool in the
Loads group.
The Add Load Combination dialog opens.  Type a unique Name and (optional) Description for this load combination.

Select the
Type of combination method to use.
 Linear – A pure
algebraic load combination in which the results of all constituent cases will
be algebraically added.
Ex.: ${f}_{1}\times {L}_{1}+{f}_{2}\times {L}_{2}+{f}_{3}\times {L}_{3}$
 SRSS – The
square root of the sum of the squares method of combination.
Ex. ${f}_{1}\times {L}_{1}+{f}_{SRSS}\times \sqrt{{f}_{2}{L}_{2}^{2}+{f}_{3}{L}_{3}^{2}}$
 ABS – Algebraic
combination of absolute values.
Ex.: ${f}_{1}\times \left{L}_{1}\right+{f}_{2}\times \left{L}_{2}\right+{f}_{3}\times \left{L}_{3}\right$
 Linear – A pure
algebraic load combination in which the results of all constituent cases will
be algebraically added.
 For SRSS combinations, type an SRSS Factor.
 To filter the types of load (i.e., dead, live, etc.) included in the load combination:

To specify the load factors used for each load case:
 Click in the Factors field.
 Type the load Factor to use as a multiplier for the load case.
 (Optional) Check the SRSS option for any load cases to be added by the SRSS method in a SRSS load combination. Load cases that do not have this option checked will be added algebraically in an SRSS combination.
 Click OK.