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CHARGES ROULANTES / MOVING LOADS

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Message 1 of 8
antoine.carimalo
1221 Views, 7 Replies

CHARGES ROULANTES / MOVING LOADS

Bonsoir,

 

Comment modéliser un convoi avec plusieurs cas de charge ?

 

Pour une verrière mobile soumise à la neige et au vent

 

Je créé par exemple:

 

une charge mobile dans le cas G (15 composantes)

une charge mobile dans le cas S (15 composantes)

une charge mobile dans le cas W (15 composantes)

 

J'obtiens des combinaisons beaucoup trop lourdes et non réalistes :

G+W : 225 composantes

G+S : 225 composantes

G+S+W : 3375 composantes

 

Comment faire comprendre à Robot que seules 15 composantes doivent être sélectionnées : qu'il y a qu'un seul et même convoi

 

//////////////////////////////////////////////////////////////////////////////////////////////

 

Hello,

 

How to design a moving load with many loading cases?

 

For a moving Skylight. Wind and snow analysis for exemple

 

I define one moving load in each loading case

 

mobile dead load G (15 composantes)

mobile snow load S (15 composantes)

mobile wind load W (15 composantes)

 

After combining Robot gives

G+W : 225 composantes

G+S : 225 composantes

G+S+W : 3375 composantes

 

This is no sense ! In the moving skylight exemple we need only 15 composantes. How it can be done like it?

 

 

ANy idea?

7 REPLIES 7
Message 2 of 8

Hi


 

I define one moving load in each loading case

 

mobile dead load G (15 composantes)

mobile snow load S (15 composantes)

mobile wind load W (15 composantes)

 

After combining Robot gives

G+W : 225 composantes

G+S : 225 composantes

G+S+W : 3375 composantes

 

This is no sense ! In the moving skylight exemple we need only 15 composantes. How it can be done like it?

 

 Why do you expect 15 combinations?

 

Calculations as follows:

 

G+W : 225 composantes = 15*15

G+S : 225 composantes = 15*15

G+S+W : 3375 composantes = 15*15*15


 



Rafal Gaweda
Message 3 of 8

Hello,

 

Thak you to respond!Smiley Happy!

 

I don't expect 15 combinaisons but I need 15 component cases for each combinaison

 

The 15 component cases correspond to effective position along the convoy movement

 

Ok if I have N mobile cranes I will expect 15 to the power of N component. Where N is the number of mobile live loads in the combinaison considered

 

But in the case of a the moving skylight I have only one convoy. But reaction on the road comes from the wind, the snow, dead load, live load ...

 

Exemple :

Lenght of road : 14 meters

Road divided each 1 meter

 

The combinaison of W + LL must have 15 components

Robot considers 15^2=225 components

225-15=210 components cases are not good.

 

Is it possible to select the component cases to combinate?

Do you know another way to solve such an exemple?

 

Cordially

 

 

 

Message 4 of 8

Take a look below.

Small example 1 DL , 1 LL ,1 moving load case with 15 components.

In case of manual combinations you should get 15 combinations:

 

manualcomb.jpg

 

If you generate automatic combinations eg for ULS only (LL acts OR_INCLUDING with moving loads) you will get 94 combinations because of acting \ not acting live loads simultaneusly and differrent factors:

 

automatcomb.jpg

 

If it is not the case please upload your model \ even simplified just to show me what and how you defined laods, combinations etc



Rafal Gaweda
Message 5 of 8

Hi,

 

To avoid misanderstanding I share screenshots

 

If I use either automatic or manual generation it is the same.

 

See the following exemple :

I define 3 mobile loads

Mob DL, Mob LL and Mob W

Each is 13 components

1.jpg

 

 

In the combination  SLS 2, i obtain 169 components (13x13), because SLS 2 refers to 2 moving loads

4.jpg

 

For instance the component 65 is not in accordance with my design concept

I need only 13 component cases for each combination that comrespond to the alignment of the 3 mobile loads

 

Is it possible with Robot to select components we want to combinate ??

Is it possible with Robot to define one convoy acting on many cases ??

How to slove the moving skylight exemple??

 

For now because of delays I am going to use the old design method which consistsin :

- create as many nodes as you want in you beam/road to describe the convoy movement

- create as many loading cases more as you have nodes primary defined

- aplly loads on the nodes

- create manually as many combination more that you defined nodes in the first step

(when I think I have 8 winds to consider with french regulation, it is an hardly job)

 

Any solution to propose?

 

Cordially,

 

Antoine Carimalo

 

Message 6 of 8


acarimalo wrote:

For instance the component 65 is not in accordance with my design concept

 

If you look at your screen capture: select component on "Composande du cas" window and use Creer cas... button

 

 

Is it possible with Robot to select components we want to combinate ??

 

See above and at the screen shot below

 

moving.jpg

 

 even if you have manual combinations or manual combination(s) from conversion of moving load combination component

you can select them this way:

 

combin.jpg

 

Is it possible with Robot to define one convoy acting on many cases ??

 

If you mean convoy as a set of loads (= vehicle) - of course it is possible


How to slove the moving skylight exemple??

 

Hope everything what is above helps.

 

 



Rafal Gaweda
Message 7 of 8

Hello,

 

I was busy on other projects sorry

 

Acording to your proposition, I still maintain that the "moving load" option can't solve my building concept because :

 

1- The button "creer cas" create only a virtual case (for visual use only) :

  • the create case doesn't appear in the generator of combinations
  • if I run a new calculation the virtual create case disappear from everywhere

2- Selecting case components manually among thousands of combinations (stage 2/2 : generator of combinaisons) is not very helpfull.

 

 

Finally to solve the problem I use a static analysis model including the static cases during movement : SW DL 2LL 8 W 2 T

I have selected a semi manual option to solve problem of combinations :

- Define the critical position with the help of moving loads as define above (6 positions)

- generate cases for each critical position

- automatic generation for the first position (around 700 combinations)

- export combinations table to excel

- use the excell options "looking for" and "remplace by" to generate the combinations for other positions

- import all combinations in the model (near 4000 combinaision)

 

Then I have two more models runing in modal analysis correponding to the position "OPENED" and "CLOSED"

 

Design succeed thanks

 

CordiallySmiley LOL

 

Message 8 of 8


acarimalo

 

1- The button "creer cas" create only a virtual case (for visual use only) :

  • the create case doesn't appear in the generator of combinations
  • if I run a new calculation the virtual create case disappear from everywhere

 

I guess you mean something different because these cases are not witrual:

 

MOVCASE.jpg



Rafal Gaweda

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