WIND LOADS GENERATION

[StefanoPasquini6790]

Hi everyone, I have a lot of doubt in "wind loads generation". I've read the validation document and I find it very very clear.

Well, I'm starting with the design of an high-rise steel building (15 stories) located in Algeria, on top of a falesia, so the wind analysis absolutely fundamental.

The plant of the building is not mentioned in the type of structure in the code then I need to evaluate the behaviour of the building with the cfd analysis.

First question:
How can I count the pressure coefficient, specially Cpi?

Second question:
How can I define correctly the velocity factor for the wind. Let me explain:

In the Algerian code (and it's the same in the Italian one and in the Eurocode...) I have a the exposition coefficient curve [Ce(z)] that depend by the rugosity coefficient [Cr(z)] and the topographic coefficient [Ct(z)] and the z value. Often, for high rise building the top value of Ce(z) is higher than 3 that is the maximum value that can be choosen in the velocity factor definition.

In the same code I have also the opportunity to define the average velocity curve Vm(z) then, which of the two curves I have to define into Robot?? The following file show the couple of curves and the relative data: https://www.dropbox.com/s/ouqd7cbya5dq42b/calcolo%20vento.xlsx

The attached file is the model of the external claddings that describe the shape of the building, as you can see in the following pic when I run the wind load calculation I have an error message and the load generation will stop. What is the issue in my model???

I'm sorry if my questions are banal, but after some calculation and comparison with the theoretical pressure I can't find the right way to use this amazing tool. When you show this tool to the costumers, they are absolutely shocked!!!

file here: https://www.dropbox.com/s/5nyckilvok3m9s5/Analisi%20Preliminare%20solaio_CFD.zip

[Rafal.Gaweda]

I do not know if it is suitable for you  but workaround for now : Reset wind profile -> one coeff 1.0 for whole heigth for sure  works

[StefanoPasquini6790]

HI,

my question is: How do they do in the validation procedure for high-rise building posted last week on Linkedin by Brian Frank??

And the wind curve to use???

Thanks

[Rafal.Gaweda]

Article:
http://bimandbeam.typepad.com/bim_beam/2014/06/autodesk-robot-structural-analysis-professional-wind-...

[StefanoPasquini6790]

Yes, I read it and I very much appreciated.

I have to do the same for my building.

Greetings

[Rafal.Gaweda · Accepted solution]

Workaround:

[StefanoPasquini6790]

Great great great....

the issue was the velocity curve too near to the "3" limit, as you suggested I've defined an higher reference velocity and I've reduced the curve.

Well, now I've two question again:

1) Is there the opportunity to define the curve using the excel table instead of graphical definition??? This is a boring tool, it will be wonderful in the curve can be defined as in the TH function...

2) wich is the right curve for velocity???

Greatings.

[Rafal.Gaweda]

1) Is there the opportunity to define the curve using the excel table instead of graphical definition??? This is a boring tool, it will be wonderful in the curve can be defined as in the TH function...

I will register it as improvement request.

[StefanoPasquini6790]

Good Morning,

I'm going on with the reliability of the wind tunnel in Robot, specially for the determination of the right curve to use for calculation and to define which code parameters to use to have a wind simulation similar to code loading.

In this link: https://www.dropbox.com/sh/870s38bn5o3zsdz/AADZ8NZlVYWvVw1gD53eWRB8a you can find an example made using the Algerian code that (file Excel with the wind property, robot model with geometry and loads and part of the code with the example made), in the annexes, have any example and reference values.

I found that the sum of forces in X direction is very close to the code ones, it happened something strange in the Z direction!!!! Example says that the sum of the value is about 90 KN, in Robot I have 1022 KN???? What's wrong???

I have one more question: When I made a wind load generation, I have to select only the panels that define the edge of the structural model or I have to select the whole structure (panels and bars???)

Thank in advance for your commitment, greetings.

[Rafal.Gaweda]

When I made a wind load generation, I have to select only the panels that define the edge of the structural model or I have to select the whole structure (panels and bars???)

Theoretically it does not matter but more realistic behavior is when you use claddings only ( 615to1814 ) in  this case.

[Rafal.Gaweda]

it happened something strange in the Z direction!!!! Example says that the sum of the value is about 90 KN, in Robot I have 1022 KN???? What's wrong???

According to 2D wind generation (one bay) Wind Simulation in 3D behavior is correct.

See below.

[StefanoPasquini6790]

Hi Artur, can you send me your model with wind genration?

Greetings

[Rafal.Gaweda]

Here you are.

[StefanoPasquini6790]

Thanks a lot....as always.

Greetings

[Anonymous]

Hello Stefano,

could you please repost the attached item? I am stuggling with wind load simulation and I would find it really useful.

Thank you in advance.

[Anonymous]

Hello Stefano,

could you please repost the attached item? I am stuggling with wind load simulation and I would find it really useful.

Thank you in advance.