WAFFLE / RIBBED SLABS IN STAAD.Pro

Question

Hi, 
 Does anyone know how to design a Waffle / Ribbed slab in STAAD.Pro?, or if there is any video available explaining how to do it?, any example?, In the R/C design module can be performed? 
 Right know I'm doing it with slab and beam elements. 
 Regards.

Seth Guthrie · Answer

You can use a combination of slab and beam elements, but by default those will be centered vertically which isn't quite right analytically speaking and dealing with offsets can get complicated. Ram Concept offers an easier way of modeling waffle slabs in my opinion, but even then the design can be rather tedious. 
 I suspect that a lot people simplify the problem. They might assume an equivalent stiffness solid plate, or they might model the beams in both directions like a grid with no slab at all, or they might focus on a single strip. 
 I see some papers online covering some of these alternatives. I even see one patented strut-and-tie approach that's interesting. I would love to hear from other users who have faced this problem and what approach they found to be the best.