I have a query regarding how to model a steel deck plate (6mm thick) supported on 100x65x7thk angles which are fully welded to the underside. The floor is made up of 533 deep UB sections spaced at 4m centres. The angle stiffeners span 4m between the beams, at 750mm centres and the 6mm steel deck runs over the top of everything.
I first modelled these angle stiffeners as a user defined section with an angle and long top flange (a 750mm 'T' section) but when I tried to analyse these in Staad (code check to AISC ASD 9th Edition) the error came back that Staad cannot check chapter G of the code for plate girders, as the classification ratio is too high. I realise that this may not have been the most accurate method of analysis but it would suit my purpose.
If I am to model this as a plate element with beams offset below (offset angles and UBs) how can I be sure the members are acting compositely? I appear to be getting big utilisations for the angle sections and relatively low absolute stress in the plate. The plate is designed to restrain the angle in bending.
Also, is there a quick and simple way to mesh a plate where the beams are not in a regular pattern across the floor? I seem to be always getting beam/plate connectivity problems when I apply the mesh as the boundary nodes are not always coincidental for adjoining plates. I don't want to spend days trying to mesh every single little piece of floor plate as there are 6 different floors in total.
Any help would be much appreciated.
Thanks
Hello angus_mck,
This is the same problem i encountered before when I analyzed the strength of the steel floor deck.
I'm able to do this by using equivalent sections. To create an equivalent section for steel deck with angle stiffeners just go to staad pro. v8i > section wizard > section builder. Then in section builder you have to model angle stiffener attached to the deck and hit the equivalent section finder..then on your staad model , create user table using the equivalent section...