topic RC slab design in Robot Structural Analysis Forum

RC slab design

romanAV48J — Thu, 06 Feb 2025 10:12:28 GMT

I am designing a relatively simple thick RC slab.

The analysis indicate defections equal to 18mm. The bending results are as expected.

In the reinforcement design the deflection's are shown as 101mm and the rebar required way above the expected.

Why is there such a great difference between the deflections in the analysis and the reinforcement design module.

Re: RC slab design

Simau — Fri, 07 Feb 2025 09:13:34 GMT

Hi @romanAV48J

Could you zip and atach your model

Re: RC slab design

romanAV48J — Fri, 07 Feb 2025 09:21:02 GMT

The zip file is attached. Many thanks.

Re: RC slab design

romanAV48J — Fri, 07 Feb 2025 09:55:08 GMT

Hi Simau,
The model is attached. Hope that you will get it.

Many thanks,

Roman

Re: RC slab design

Simau — Fri, 07 Feb 2025 11:46:53 GMT

Hi @romanAV48J

First are you sure about the direction of the LL1 load case.

You can't compare the deformations from Maps and those calculated in required reinforcements which depend on the parameters in "reinforcement type"

I created new ULS and SLS combinations according to the BS code to design the slab:

Model attached

Re: RC slab design

romanAV48J — Fri, 07 Feb 2025 13:01:46 GMT

Thank you for this Simau.

The model is of an shaft base. The LL is due to water pressure/heave this is why it is pointing up. The FOS are also slightly different from the FOS in the codes.

I an relatively new to Robot and still getting grips of how it works. In the slab model V1 there 2 different displacements indicated. One 8mm the other 20mm. What loading condition do the 8mm and 20mm represent? Does the reinforcement area (required/provided) affect the deflections output? Can the crack width limit be changed in "reinforcement parameters". I have tried to change the crack width limits as an experiment but it did not affect the results.

All the best

Roman

Re: RC slab design

Simau — Fri, 07 Feb 2025 15:25:18 GMT

Hi @romanAV48J

I recommend you to watch this webinar (starting at 19:25)

https://www.youtube.com/watch?v=YvVRNFH8_cc&list=PLY-ggSrSwbZqow_60fiqJwS69mg1nQMzk&index=5&ab_channel=AutodeskBuildingSolutions

Re: RC slab design

romanAV48J — Fri, 07 Feb 2025 15:27:31 GMT

Much appreciated. Thank you for your time and help.