How can I combine generated moving loads with other loads in my model?

You should use the ADD LOAD option as explained below for combining other existing load cases with generated moving load cases. If you need to add multiple such existing cases to the generated moving load cases, you have to first define a REPEAT LOAD ( and not a LOAD COMBINATION ) for combining the primary loads and then add that REPEAT LOAD with the generated moving load cases. For example if you have a situation where you would like to add dead load ( load case 1 ) and imposed load ( load case 2) with the generated moving load cases, you would first define a REPEAT LOAD ( load case 3) which would combine the loads 1 and 2. Subsequently this load 3 would be added to each generation of the moving load case as explained next.

LOAD 1 DEAD LOAD
SELFWEIGHT Y -1
LOAD 2 IMPOSED LOAD
MEMBER LOAD
1 TO 6 12 TO 17 23 TO 28 34 TO 39 45 TO 50 UNI GY -1
LOAD 3 DEAD + IMPOSED
REPEAT LOAD
1 1.0 2 1.0
LOAD GENERATION 10 ADD LOAD 3
TYPE 1 7.5 0 0 ZINC 10

Here is the option in the GUI that would allow you to add the REPEAT LOAD case ( load case 3 in this example) with the moving load generations