topic Re: Slab Modelling advice in Robot Structural Analysis Forum

Slab Modelling advice

Anonymous — Tue, 27 Mar 2018 16:37:57 GMT

Hi all,

I would appreciate your advice regarding an analysis of a ground floor slab. It is a 350mm RC suspended slab. The slab is supported on pile caps and 900mm deep raft foundations shown in the first and second images attached. There are also ground beams spanning between a number of pile caps highlighted in green in the same image. The loading from my columns and walls is going straight into the pile caps.

My question is what the best approach would be for modelling this in Robot. The geometry of the slab is presented in the final image attached. The purpose of this analysis is to obtain an adequate design for my ground floor slab (Reinforcement, deflection etc). I was thinking that it may not be necessary to model in the foundations placing fixed linear supports at the edge of the slab to model this condition for the rafts. I was also thinking that I could place linear pinned supports of 700mm to model the ground beams. I am uncertain on what the correct and most efficient way of modelling this would be to obtain satisfactory results for my ground floor slab. Any advice is appreciated. Thanks

Re: Slab Modelling advice

Anonymous — Wed, 28 Mar 2018 12:39:51 GMT

Hi, Artur/Rafa any ideas?

Re: Slab Modelling advice

saclovitzky — Wed, 28 Mar 2018 15:38:17 GMT

In areas where the slab are supported by pile caps, used nodal support(support definition-advanced/column-filled-up "a"/"b" as the dimension of the pile cap).

In areas where it is supported by raft foundation, used line support(for simplicity). Hope this helps.

Re: Slab Modelling advice

Anonymous — Wed, 28 Mar 2018 16:10:15 GMT

Thanks for that. I will try both modelling approaches and see results

Re: Slab Modelling advice

Artur.Kosakowski — Wed, 28 Mar 2018 15:46:13 GMT

Hi @Anonymous

I'm happy to assist you with use of a particular RSA features but I don't think I'm in the position to tell which design approach is better. My advice is that when in doubt try both and compare the results.

Re: Slab Modelling advice

saclovitzky — Wed, 28 Mar 2018 16:13:12 GMT

Pls. see attached.

Re: Slab Modelling advice

Anonymous — Wed, 28 Mar 2018 16:36:17 GMT

I attempted to implement something similiar to your image above yesterday but I could only apply linear supports to the edge of the slab. Is there a way of applying linear support to the locations you've displayed in the image? Thanks btw

Re: Slab Modelling advice

Anonymous — Wed, 28 Mar 2018 17:25:50 GMT

I should have clarified without having to model walls

Re: Slab Modelling advice

Rafacascudo — Wed, 28 Mar 2018 17:46:17 GMT

You can draw/create a line anywhere inside the slab area and then assign linear support to it . Supports will be created on the generated nodes along the line same way it is done at the panel edges

Re: Slab Modelling advice

saclovitzky — Thu, 29 Mar 2018 13:43:25 GMT

use lines(polyline-contour/lines), then assigned support to it.

Re: Slab Modelling advice

Anonymous — Wed, 04 Apr 2018 10:30:43 GMT

Thanks alot I am looking at the design now so hopefully results will match hand calculations.