A few questions:
1. Is the only way to account for the lateral stiffness of a steel roof deck or checkered plate floor by modelling plate elements and assigning a stiffness, or can the MASTER/SLAVE ZX command be used?
2. I am modeling an existing building in which the floor structure is made up of wood pack flooring sitting on top of deep steel beams. Is the MASTER/SLAVE ZX command accurate in this situation or would I need to model plate elements?
3. Is there a different way to use joists in a Staad model where they will actually be representative of more than their own self weight? I am also modeling a warehouse structure where the designer would like to use long span joists at 5' o/c in one direction(120'). I have only modeled the joists at the column lines(25' o/c) where they will have a bottom chord brace back to the column. When I run my model with lateral load, the joists provide no stiffness and my deflections are more than unrealistic. To fix this I put in very heavy W shapes and make sure to exclude the self weight. This brings the deflections back into a reasonable range, but would like to think there is a more accurate way to do this. Any suggestions?
Suggestions would be appreciated.
Thanks,
Kyle
Here are the answers to the questions
1. A steel roof deck without concrete filling or a checkered plate floor are usually not considered as rigid diaphragm and so using master slave ZX will not be appropriate. If you would just want the loading on the deck to be distributed to the supporting beams and including the lateral stiffness due to the deck is not important, using the FLOOR LOAD option may be good enough. However if accounting for the lateral stiffness of the diaphragm is important, you can model the diaphragm using plates.
2. Wood pack flooring also is generally not considered as a rigid diaphragm and so using the Master Slave ZX will not be appropriate. Possible modeling options are discussed under response 1.
3. The joist implementation in STAAD.Pro does not account for these members in the stiffness analysis. So if you would like your joists to contribute towards the lateral stiffness, model these using equivalent user defined wide flanges. You may also model these using user defined general sections where you can directly key in the geometric properties like moment of inertia.
Answer Verified By: KYLE