RAM Concept - Flat slab ductility failure

[dadomago75]

Hi everybody,

I am fairly new to RAM Concept but I already got hands on most of the Layers to check.
I am currently dealing with a flat slab with few transfers. It is ok for strength, but has few localised ductility issues that I can't solve.
I tried to reduce the number of strands (to the detriment of deflection), and to reduce the drape, with no success.
I also increased the thickness from 300 to 350mm, but even so, it still gives the same localised ductility errors.
That sounds weird! how can be possible that, increasing the thickness, it still gives the same ductility issue?!
Any thought/suggestion?

Thanks
Davide

 

[Trenno]

Davide,

There is the possibility RAM Concept is checking ductility requirements at 'non critical' cross sections. Where is RAM Concept calling up ductility failures?

I believe generally you need to keep an eye out for ductility at midspans and supports (where plastic hinges can develop).

 

[KootK]

Have you tried adding some mild rebar?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dadomago75]

Hi guys,

thanks for your help, but I just figured out today what was the issue.
There were user defined reinforcements that create ductility issue.
I am pretty sure I haven't added that reo! Anyway, finally I managed to solve it.

@Trenno
You are right. I have a ductility issue at the end span of a strange strip (tapered to a 300mm width). And obviously it gives the error at the narrowest section. I know it is not a ductility issue, it is just because of the extremely narrow section, so I disregard it.

@KootK
good point, but RAM automatically adds the required reo to bring the ductility within the limits.

I want to share a trick I learned today. To avoid any "design section" error:
- select the span segment in the strip.
- right click
- change from Automatic width to Manual (2nd window)
- change to Max rectangular width (3rd window)
- check that the top&btm cover are the same
- change torsion to "Wood-Armer"
- tick the box to make the middle strip the same as the column strip 4th window)

This helps to avoid mistakes on section widths.

Cheers

 

[Trenno]

Arrrr, so you had way too much tensile reinforcement making the section over-reinforced aka non-ductile.

 

[dadomago75]

Yeah, but I didn't know.
I don't know why the User defined reinforcement where there. I am sure I haven't put any reo.