RAM Concept Stiffened Raft

Greg Killen — Tue, 04 Aug 2015 10:41:21 GMT

Hello

I am using RAM Concept to design a stiffened raft slab supported on an elastic foundation. This is my first real design outside of using the tutorial material and want to ensure that the output is sensible.

Below is a screen cap of my model. For the purposes of clarity I have hatched the area of the slab and the beams are seen to have the green outlines. Note that all other lines i.e. light blue and pink are walls above and the red lines are some guides I drew in CAD to help draw the beams.

I have the following questions I would like answered if possible:

Should I be assigning any special behavior to the beams?
I have modeled some beams as continuous and some other beams as stop-start. Is RAM Concept smart enough to recognise that a junction between two beams exists and handles it appropriately without the user needing to create a node at their intersection?
This structure doesn't contain any columns - just walls. I didn't intend on modeling any walls as I don't want them to act as stiff elements that muck up the design output as a result of their large in-plane stiffness. I instead intend on modelling their self weights and associated concentrated actions due to structure above as either uniformly distributed and points loads. Is this a valid approach?
When is comes to inputting point loads my previous experience with other finite element modelling software packages alludes to there being a node under the point load. I have read of several techniques used to do this some of which include adding a very soft spring at the location of the point load. Below is a screen cap of the "point spring" properties I intend on using. Should the "Elevation above slab soffit" be equal to zero as shown in the image below even if the spring is placed under a beam?
How do I include the self weight of the raft slab itself? I have read on several pages here that it is automatically accounted for but I want to be able to view the option that sets this. This is for my own piece of mind.
a) This next question is perhaps the most important of all as I want to automate the reinforcement as best I can. How should I go about defining the design strips for such a structure? My basic understanding is that these beams and slab portions in the immediate vacinity will act as "T" beams for internal beams and "L" beams for perimeter beams. Am I correct in assuming this firstly?

6. b) I have read through the waffle slab discussion but can't garner exactly what Seth Guthrie means when he says "You can define bunches of short design strips between beams..." Why not define the design strips directly over the top of the ribs or beams (in my case)?
http://communities.bentley.com/products/structural/structural_analysis___design/f/5932/t/57656
Is there anything else anyone can add to what I may have missed here?

Thanks in advance!

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RAM Concept Stiffened Raft