Modelling Beams in Slabs

[chillerz69]

hey guys I am new to finite element analysis modelling and need to ask a basic question. Our company in the past has modelled elevated concrete slabs as a grillage of beams, and with a lot of tweaking accepteble results can be obtained. We are currently trialling the program SAFE, and comparing the results to what we calculated previously and are comfortable with. The question is, how do we model a fold in the slab? The slab is originally 200mm thick and has a 525mm step down to a 450 thick slab, giving us effectively a 975mm deep beam. In the grillage analyis we input this as a flanged section, but what do we input into the finite element model in SAFE? There is the option of rectangular beams, L beams etc. I assumed all we would have to do would be to add a rectangular beam and offset the 450mm slab downwards, but if thats the case why is L beams an option? I hope this question makes sense.
- Brent

 

[asixth]

chillerz,

I recently had a design with a fold in the slab similar to what you have described. Using SAFE, are you modelling the slab as plate elements or are you still using a grillage of beams. There is some tweaking when analysing slabs using plate elements.

I would model the slab ising plate elements and would model the slab thickening as a beam element.

 

[chillerz69]

In safe the slab is modelled as a plate element. I just assumed that the thickening would be inputted as a rectangular beam and that safe would automatically calculate the beams stiffness taking into account the effective width of the flanges of concrete surrounding it. Would you suggest calculating the effective width of the flanges by hand and inputting this as L beam etc. Cheers