Risa3D doesn't do semi-rigid or flexible diaphragms. Only rigid. For those features you need RisaFloor. You'll have to calculate them manually and apply them as line loads.
Is this a steel deck diaphragm? If so, you can use the SDI equations to get an equivalent shear modulus for the deck and use that to define plate elements at the diaphragm's elevation. This allows you to model it pretty accurately without the extra program. You need a top notch computer, though, because the number of plates and the meshing routine and subsequent calculations can take some time.
Well, if you have RISAFloor + RISA-3D then you can get semi-rigid diaphragms inside RISA-3D. I suspect that's what srazahz is talking about. Am I correct Srazahz?
I modeled the building in RisaFloor with a semi-rigid diaphragm and transferred it to Risa 3D for lateral loads.
Risa 3D treats semi rigid diaphragm as plates and the internal forces can be acquired from the sigma tool that shows up on the left after the model is solved. I was hoping to get the applied loads on the diaphragm.
You make a good point. My guess is that Ashley (who's only been with RISA a few months) has been tasked by the RISA management with "correcting" any misconceptions about the RISA software that occur on these forums.
That is a perfectly reasonable goal for her. She just needs to learn how to respond uniquely and accurately to each thread, rather than repeating a canned sales / marketing response. Otherwise her posts are going to start getting removed / censored.
