topic Re: Pile Caps with Robot in Robot Structural Analysis Forum

Pile Caps with Robot

gustavo_c_vasconcellos — Tue, 31 May 2011 20:07:21 GMT

I would like to know if it is possible to design pile caps using Robot. Thanks, Gustavo

Re: Pile Caps with Robot

Jakub.Brozonowicz — Tue, 31 May 2011 20:56:53 GMT

No chance to do it with design object like foot or the longitudinal foundation.

Most RSA users are modelling panels as elements acting the pile caps.

This idea lets to design a pile cap as RC plate with respect to its thickness and other outer conditions.

Due to code of design program checks all ULS and SLS conditions with punching included.

Re: Pile Caps with Robot

gustavo_c_vasconcellos — Tue, 31 May 2011 23:31:55 GMT

Thank you,

do you have an example that you can send to me? Gustvo

Re: Pile Caps with Robot

Jakub.Brozonowicz — Wed, 01 Jun 2011 09:28:28 GMT

Here is a simple model file.

Design as plate with simple elastic support conditions acting piles.

Run design process by code according to your choice.

Re: Pile Caps with Robot

Anonymous — Tue, 30 Oct 2012 16:11:00 GMT

Hi,

Im trying to model a pile cap, I have given the vertical force and moments acting on the column that will be resting on the pile cap.

To get the forces acting on the piles, I modeled the piles as fixed node supports connected to another node where the forces are applied. The results are satisfactory.

Tried the same thing with stiff bars, the reactions are not satisfactory.

Also will be helpful any suggestion how to apply the force in order to get satisfactory results on the plate ( pile cap).

The above cases( rigid links and stiff bars) the moments on the plate are ZERO, I think because the forces are introduced directly to the supports, and no forces act on the plate.

Please correct me if I am wrong and any help will be appreciated

Thanx

Re: Pile Caps with Robot

Artur.Kosakowski — Wed, 31 Oct 2012 09:45:34 GMT

Perhaps this will be what you need

Re: Pile Caps with Robot

Anonymous — Wed, 31 Oct 2012 10:10:56 GMT

thank you for your help, i tried what is explained in the picture.

the piles are designed as slab-rigid diafragm???what about the column force acting place also slab-rigid diafragm or flexible???

Is the force applyed as a node force-moment in a node that is in the column acting place?

Re: Pile Caps with Robot

Artur.Kosakowski — Wed, 31 Oct 2012 10:16:04 GMT

The support (pile) size is modeled as the central node plus rigid links. The column (size) is modeled as a central node with applied loads plus rigid links. The panel is defined as a shell.

Re: Pile Caps with Robot

Anonymous — Wed, 31 Oct 2012 12:06:54 GMT

Thanx again,

anyway I tried this option too, and the reactions are almost the same as using the stiff bars?! (not satisfactory)

Attached to this post is what I am trying to model in RSA, in the pdf file the model is calculated manually, I get the same results for pile reactions, can't say the same for the moments.

Any help will be appreciated

Re: Pile Caps with Robot

Artur.Kosakowski — Wed, 31 Oct 2012 13:04:07 GMT

You may add rigid links to model the influence of piles' and column's cross sections on the pile cup.

Re: Pile Caps with Robot

Anonymous — Wed, 31 Oct 2012 13:19:10 GMT

Thank you again, very helpfull

Re: Pile Caps with Robot

Anonymous — Mon, 05 Nov 2012 16:49:01 GMT

Thank you , Jakub & Artur,

for this, it will be very helpfull, for us when we have to perform this kind of analysis but you have to understand that for each changein the load or uin the geometry the user have to make new modelling process in order to create, the pile cap in the general model, so I'm asking you If RSA developers don't have plan to enlarge the Foundation module, by adding some features like design and analysis for standard pile cap such as rectangular, square, traingular and circular, as RAM concrete and Cypecad are doing it actually (see figure below in attachements). That's could be a goal to achieve because in REVIT Structure, actually thoses objects are verry well developed whitout any link with ARSA. So I tihink that pile cap design and pile analysis itself and design are two features that must be include in the future in RSA releases, in oder to follow the REVIT Structure cruise and in the other hand to keep you at the same level with the other softwares editors.

Re: Pile Caps with Robot

Artur.Kosakowski — Tue, 06 Nov 2012 14:11:00 GMT

Patrick,

I have added this request to the wish list.

Re: Pile Caps with Robot

Anonymous — Tue, 13 Nov 2012 15:01:57 GMT

Hi,

The model of a pile cap 2.1x2.1x0.8m designed in ARSA.

In the PDF file the example is calculated using a) truss analogy b)bending theory

1) truss analogy for designing pile caps in RSA is not available, but member forces and node forces can be calculated, and after a manual calculation of reinforcement can be done??

2) bending theory is available, the pile cap is modeled as a shell, the reinforcement required is provided by RSA?

Is it possible to arrange the reinforcement as in the PDF file??

In the graphoc view - slab reinforcement - reinforcement is always - top reinforcement - see picture

3) to get the right results of bending moments and shear force diagram as in the PDF file, I am using panel cut results.

Im not beeing succesful in getting the right results, can you please help me??

Thank you in advance

Re: Pile Caps with Robot

Artur.Kosakowski — Wed, 14 Nov 2012 08:53:37 GMT

The model of a pile cap 2.1x2.1x0.8m designed in ARSA.

In the PDF file the example is calculated using a) truss analogy b)bending theory

1) truss analogy for designing pile caps in RSA is not available, but member forces and node forces can be calculated, and after a manual calculation of reinforcement can be done??

Yes, the Nsd is just the total sum of vertical reactions.

2) bending theory is available, the pile cap is modeled as a shell, the reinforcement required is provided by RSA?

Is it possible to arrange the reinforcement as in the PDF file??

In the graphoc view - slab reinforcement - reinforcement is always - top reinforcement - see picture

3) to get the right results of bending moments and shear force diagram as in the PDF file, I am using panel cut results.

Im not beeing succesful in getting the right results, can you please help me??

The book uses the model as below:

and calculates bending reinforcement as for a RC Beam.

Re: Pile Caps with Robot

Anonymous — Wed, 14 Nov 2012 09:15:51 GMT

Thank you,

I understand that the book uses the beam theory to calculate the shear forces and bending moments of the plate theoretically changed as a beam.

Will it be possible to obtain close values of the moments and shear forces when the pile cap is desinged in RSA as a shell?

Re: Pile Caps with Robot

Artur.Kosakowski — Wed, 14 Nov 2012 09:41:50 GMT

Depends how you define the 'close' range. Mind that for a shell model the influence of the bi-directional behavior of the 'slab' will reduce the values of internal forces for a 'single' direction. The 1:1 side to side proportion does not look like a linear element example. You can compare results using the attached model.

Re: Pile Caps with Robot

Anonymous — Wed, 14 Nov 2012 13:31:59 GMT

Thank you,

regarding the reinforcement if it can be modified as in the pdf? or if its possible to add horizontal reinforcement links through the pile cap thickness?

also in the graphic view the bottom reinforcement appears as top one!!

Thanks again and very helpful as always 🙂

Re: Pile Caps with Robot

Artur.Kosakowski — Wed, 14 Nov 2012 13:51:33 GMT

Re: Pile Caps with Robot

Anonymous — Mon, 19 Nov 2012 11:36:14 GMT

Hello,

Im modeling a pile cap in RSA, the example is given in the pdf file.

First RSA file Pile modeling with spring nodes agrees very good with the pfd file results.

Second model of the pile cap with piles modeled as spring node supports. for moments and shear forces calculation, the reactions of the piles agree also very good. Moments and shear forced on the other hand not so much.

Maybe is that I dont understand the interpretation of the moments in RSA, or I am modeling the wrong way for finding moments and shear forces. Moments and shear forces in pdf ( page 345)

The pdf file racomends to use beams as idealized grillage elements in order to find the moments and shear forces for reinforcement design of the pile cap.

Can you please help me

Thank you