STAAD PRO - Bridge Analysis - 4 Span Continuous Unit - Help with Composite Slab and Load Distribution

Good Afternoon,

I am trying to model a bridge in STAAD Pro and I am having difficulty.

4 Span Continuous Unit (201' 260' 260' 201') - with 4 Structural Steel Plate Girders, with a composite concrete slab with overhangs on top. (39'-3" wide, beams spaces at 10'-0")

Basically I am trying to add a point load in various places across the length and width to determine how it distributes through the slab to the beams. (both moment dist and support reactions)

I have attached 2 models that I have developed to this point. One has the slab, beams, and a small support positioned such that they rest on one another. The other model has all elements at the same elevation.

I do not believe that either of these models are analyzing the structure accurately, and I cannot figure out how to put a composite slab on these beams.

Any help on putting a composite slab on these beams that would accurately model the distribution would be very helpful.