retaining wall

[saclovitzky]

Hello,

I am trying to model a cantilever retaining wall about 2.0m in height and has a 2.3m long base.

I wanted to know the actual deflection of the stem. I model the 2.3m long base with Kz value and basically assumed a basic layer of soil properties(pls. see attached). I am hoping that the stem deflection is not really far off as if you model an rc wall of similar height with a fixed support(about 11mm). But when I run the calculation the deflection of the stem produced no result(probably it is way too high.

Did I miss something in modelling the retaining wall particularly in the base slab support?

Any ideas will be greatly appreciated.

[napooil]

You should be fix or input value in kx and ky .

[saclovitzky]

Thanks Napooil but what is the basis for the values of 10 kN/m3?

[saclovitzky]

Still doesnt work

[saclovitzky]

I see the thread below and analyzed the ret. wall using non-linear analysis for whatever reason? Anybody who have the experience in modelling retaining wall in ARSAP? 

I am hoping that spmebody will share his/her expertise in modelling ret wall.

For the developer, this is one area that can be added to ARSAP.

https://forums.autodesk.com/t5/robot-structural-analysis-forum/retaining-wall/m-p/4468207/highlight/...

[saclovitzky]

Any comment Artur/Rafal/Rafascudo?

[Rafacascudo]

Hi,

You got to have horizontal supports .

That instability type 3 cannot be ignored and you are getting weird results for your model because of it.

Look at comb1 soil reactions below. Unsymetric results for a totally symetric load in a symetric structure about X axis

So I set 100kn/m3(shall be a lot more) for kx and ky on thickness definition. You set the corect values according to the soil data you have.

Also , There is Uz+ uplift ,otherwise your soil will be resisting tension. So ...

And then analysis will be nonlinear . Set loads 1to3 to auxiliary ,and you will get much better results for the combinations

Then ,when you set the correct kxy values(or maybe fix the slab XY directions) you will get a good value for the stem deformation

My version of the model (Robot 2018)attached

[saclovitzky · Accepted solution]

Thanks Rafascudo, I still dont have a chance to look at it. Autodesk should pay you for this

[Rafacascudo]

That is not a bad idea!!

[saclovitzky]

Hello Rafascudo,

Can you saved it in 2017 version?

[saclovitzky]

Hello Rafascudo,

How do you change the analysis type from static to non-linear analysis(pls. see attached).

Also, regarding the values for kx /ky where do you normally get this, is it related to Kz values or soil bearing capacities?

Can you show the actual deflection on the stem?

Again, your comment is highly appreciated.

[Rafacascudo · Accepted solution]

1 - Never needed to set horizontal elastic supports for soil , but it may be a function of Kz.

2- Nonlinear analysis is set automatically by Robot as you you introduce non linear elements like support uplift , tension or compression only bars ,etc

3- with kx ky equal to zero and setting a rigid Ux,Uy support on slab far edge , you get this deformations on top of wall

Robot 2017 file attached

[saclovitzky]

Thanks Rafascudo for your reply.

 It seems to me to get at least an accurate bending moment at the stem, it needs to have a decent value for kx/ky and Kz.

 While to get an acceptable deflection result(make another model), kx/ky shld be equal to zero and provide edge (fixed-tick only ux, uy) support. Is this correct?

Retaining wall design should be another "add-in" that needs to be incorporated in the future release of ARSAP(maybe ARSAP 2019).

[Rafacascudo]

Moment at the base of the vertical wall will always be the same , despite of the support conditions , making sure the structure is stable. It's a cantiliver!!!
Same for deflection as difference between top and botton of wall horizontal displacements will not depend on support conditions.

[saclovitzky]

One thing that puzzled me, is that, if you have a value for kx/ky and Kz, the moment diagrams are reasonable(but conservative). This is the model without the support at the far edge of the base.

If this is the case, then, this same model should be the basis for deflection as well. I believe that providing values for kx/ky/Kz provide necessary spring support already on every nodes generated on the base, that's why there's no need to provide support at the far edge(and make kx/ky=0). Am I correct on this?

Also, when I look at the same model and checked its deflections, it turns out erroneous.

Any explanation for this?

[Rafacascudo · Accepted solution]

Moment for model with kx,ky , and with fixed Ux,Uy at the far edge

Displacements on Global X direction for both options

[saclovitzky]

Thanks Rafascudo, it is loud and clear