## Robot Structural Analysis

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic to the Top
- Bookmark
- Subscribe
- Printer Friendly Page

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

* *

*I calculated the impulsive force and mass induced by the method of HOUZNER and got the following results: Fi (impulsive force) = -4562 KN and Mi (impulsive mass ) = 1028 t.*

*how can I enter these values?*

* *

*What is that?*

*1- I used Houzner's method to calculate hydrodynamic forces generated when seisme happen and I obtained the results above, I want now assign the mass calculated (Mi=1028t) to my model, so pls do that for me (I attached my file below)*

* *

We found this article : http://authors.library.caltech.edu/26535/1/Housner

Our understanding is that you have to calculate mass for each "strip" and apply them on model. You can do it by connecting liquid strip center of gravity (each) with applied mass to walls - in robot by rigid links, thus this approach will make model not real - too stiff. You have to distribute this mass (for each strip) to wall nodes of this strip to make it more real.

If our understaning is not correct please explain.

**Rafal Gaweda**

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

Hi Rafal,

Thx for your reply

and for enter mass value that I calculated as shown above, can you do that for me pls or make a demonstration to enter correct value?

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

My assuptions = example

The strip (in red) - "3 rows of nodes":

36 - number of nodes of circle

Mi=1028 (strip mass)

mass applied to any node from yellow set = mass applied to any node from green set = 1028 *0.25 / 36 =257

mass applied to any node from blue set = 1028 *0.5 / 36 = 514

these masses should act at least in XY directions or XYZ , apply them to Modal case

or as forces in masse_eau case (I guess) and then convert this case to masses

**Rafal Gaweda**

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

Hi,

why you chose the tower in your example, the mass should be applied to the tank!

look at my capture below, my modeling is correct according to your demonstration?

thx.

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

why you chose the tower in your example,

For the simplicity.

look at my capture below, my modeling is correct according to your demonstration?

Yes.

**Rafal Gaweda**

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

I think it is not correct, because I noticed that the forces directed along the Y axis are not diametrically opposed!?...They must be oriented along the local axis!

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

Pls Rafal, enter these values in my model, I will be very grateful

thnks

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

normally the mass must be applied along the axis 3 of noueds, but how to do that?

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

Hi,

my modelization is correct now?

I used uniforme planar load on contour to define load!

thx.

# Re: elevated conical tank:seismic and hydrodynamic loads calculation

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

Rafal.Gaweda wrote:My assuptions = example

The strip (in red) - "3 rows of nodes":

36 - number of nodes of circle

Mi=1028 (strip mass)

mass applied to any node from yellow set = mass applied to any node from green set = 1028 *0.25 / 36 =257

mass applied to any node from blue set = 1028 *0.5 / 36 = 514

these masses should act at least in XY directions or XYZ , apply them to Modal case

or as forces in masse_eau case (I guess) and then convert this case to masses

1-Why u've chosen 3 rows of noeds? why not 4 or 5...or simply 1 ? and how can I know the exact level for applying masses?

2- If I chosen to add masses in modal case, should I select more rows too or apply them simply in 1 row ?

3- I've enter the values such as you indicated in "masse_eau" case then convert them to masses, but when I launched calculation, this error message appears

so I've applyed them in modal case, and I obtained the results below, which seem to me wrong, especially the sum of the masses in the modal analysis and the moment along the Y axis and the shear along the X axis in combination case "G+Q+E"

thx

so