Steel roof truss on concrete beams and columns

Question

Dear all, 
 I am relatively new to STAAD Pro. I have been able to model my building frame in reinforced concrete as well as some roof trusses in steel sections including Zed purlins. I have 3 issues: 
 1) how to model roof loading to transfer roof loads from purlins to truss members at the nodal points. 
 2) how to connect the steel roof structure to the underlying concrete roof beam/column support so that truss reactions are picked up by the roof beam/column support as point loads. 
 3) any need for extra bracing to roof structure beyond the Zed purlins provided? 
 Thanks. 
 Josh

Sye · Answer

1. If you have modeled the purlins, you may apply member loads on the purlins. The loads are going to transfer from the purlins to the roof truss at all node locations where the purlins are connected to the roof truss. 
 2. Ensure that the steel roof structure shares common nodes with the concrete supporting structure below. This would automatically ensure connectivity and ensure proper load transfer 
 3. Take a look at the analysis and design results. Nodal displacements and utilization ratios of the members would give you an idea as to whether you need extra bracings.