Hello,
As correctly in the above post, you can apply the moving horizontal load using the Notional load option. It was introduced to address a requirement of the AISC 2005 code's Direct Analysis method, which is that the structure needs to be analyzed for lateral loads which are a certain percentage of the gravity loads.
Using this feature, you can instruct the program to generate lateral loads from the wheel loads generated for the moving load case. It has 2 limitations:-
1) It generates lateral loads only at the joints of the structure.
2) It generates loads along global X and Z only.
Limitation 1 can be overcome if you create a number of nodes along the length of the beam. So, if a wheel load falls at some point on the member span, and a node is located near that point, the notional load will be generated at that point.
Limitation 2 means that the crane girder needs to be spanning along global X or Z. If it spans at some inclination to those axes, the notional load will still be generated along global X or Z only.