Staircase Analysis

Question

Good Day, 
 I have modeled a staircase in Staad using beam and plate elements, but I am unsure about the suitability of the model. My main issue I have relating to the model is whether or not the analysis results obtained for the columns are accurate enough to be used for design, as it is clear that the slabs/plates are playing a part in moment transfer for my loads? 
 NB: In modelling the Staircase I ensured to apply all my earthquake loads manually to only the columns in the frame as I noticed that the automatic seismic generator would break up the seismic load on the plate elements as well. 
 I have uploaded the model as a reference. 7041.STAIRS-frame.zip

Sye · Accepted Answer

There are few overlapping plates in the model that you can check by going to Tools > Check Improperly Connected Plates. Also check the beam plate connectivity by going to Tools > Check Beam Plate Connectivity. The slabs defined as plates would contribute towards the lateral stiffness of the structure and would influence the force distribution. So what I see is the expected behavior. Applying seismic load at the appropriate elevations is fine. I assume you are accounting for both inherent torsion ( due to dyn eccentricity) and accidental torsion in the applied MY itself.