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time history analysis

31 REPLIES 31
Reply
Message 1 of 32
dziub7
796 Views, 31 Replies

time history analysis

Bonjour,

je veux faire une analyse temporelle d'une structure non lineaire (passerelle haubanée).

J'ai mon cas 1 poids propre, que j'ai transformé en masse

cas 2 analyse modale

cas 3 le cas de charge de piéton

cas 4 analyse temporelle, methode de Newmark, j'ai défini ma fonction et mon cas 3

 

je n'obtiens pas les bonnes valeurs d'accélération.

quand j'affiche les réactions, j'obtiens presque les memes valeurs dans le cas 1 et 3

est ce que le problème vient de là??

merci d'avance

31 REPLIES 31
Message 2 of 32
Rafal.Gaweda
in reply to: dziub7

PLease send us the file.



Rafal Gaweda
Message 3 of 32
dziub7
in reply to: Rafal.Gaweda

what is the best way to send the file?

Message 4 of 32
dziub7
in reply to: dziub7

 
Message 5 of 32
dziub7
in reply to: dziub7

anyone???

Message 6 of 32
Rafal.Gaweda
in reply to: dziub7

be patient. We are cheking it.



Rafal Gaweda
Message 7 of 32
Rafal.Gaweda
in reply to: Rafal.Gaweda

All cases must be pdelta.

NOTE - now calculations will last at least ~1,5h with THA NON tolerance 0.001, with tol 0.0001 - 2,5h

 

thanon.jpg

 

File with results: https://www.filemail.com/dl.aspx?id=HHLXBXCYWHRISCC



Rafal Gaweda
Message 8 of 32
dziub7
in reply to: Rafal.Gaweda

Hi RG,

thank you to take time to look into the model!

I think there is something wrong with the results: because if you look the loads i put

in case 3 "pedestrians" : 12.7N/ml, is almost nothing and the max results of acceleration is

8m/s² !! is there something wrong with the loads taking into account in load case 3? 

Message 9 of 32
dziub7
in reply to: dziub7

hi there,

do you have an idea about the question?

Message 10 of 32
Rafal.Gaweda
in reply to: dziub7

Tomorrow.



Rafal Gaweda
Message 11 of 32
Rafal.Gaweda
in reply to: Rafal.Gaweda

Next run of calculations over this night (1500 increments).



Rafal Gaweda
Message 12 of 32
dziub7
in reply to: Rafal.Gaweda

hi Rafal,

did you find something interesting?

 

 

Message 13 of 32
Rafal.Gaweda
in reply to: dziub7

For now - no

Hopefully next set of results will be available in 10h.



Rafal Gaweda
Message 14 of 32
dziub7
in reply to: Rafal.Gaweda

OK, 10h of calculations Smiley Surprised

 

when i look in the acceleration results in the model you send to me:

 

- biggest acceleration are in nodes 116 135 374A376: all are where the cables connect to the rigid element

if we look for node 116, max acceleration is 1m/s²; in node 114=0.37m/s²

 

- i have to study the acceleration in node 93, where, I think, should be the biggest acceleration, (since, it is the place of maximum deformation in first mode of the modal analysis) maximum value is 0.46m/s² ; the person who studies the problem before me found: 0.15m/s².

 

- about the main element of the bridge: elements from 366 to 406: today elements mesure 3m, do you think I have

to divide them more?

 

again thank you to take time on this model!

see you tommorow...

 

 

 

 

 

 

Message 15 of 32
Rafal.Gaweda
in reply to: dziub7

around 50h more to go

 

77h.jpg



Rafal Gaweda
Message 16 of 32
Rafal.Gaweda
in reply to: Rafal.Gaweda

Happy Easters

 

107.jpg



Rafal Gaweda
Message 17 of 32
dziub7
in reply to: Rafal.Gaweda

Hi,

did you get any results?

 

Message 18 of 32
Rafal.Gaweda
in reply to: dziub7

Not converged 😞 starting from 625 step

 

625.jpg

 

 

As you may see from the diagram above it is still "accelerating".

Do you expect such behavior or maybe damping is too low?

 

Calculation started with settings as below:

 

0002.jpg

 

expecting results in a week(?) or so.



Rafal Gaweda
Message 19 of 32
dziub7
in reply to: Rafal.Gaweda

Hi RG,

i don't understand why its not converged, first time when you send me the model,

you find results.

I see the diagram is still accelerating, I expect such behavior during several time, but should

stabilize after this time, Im looking for the value when it is stabilized. I tried the same analyse during 30s, and it still accelerating, but not much.

Im doing it during 50s right now but calculations take a very long time!!!

concerning your setting: time step of 0.002s may be too long to calculate, don't you think?

Message 20 of 32
Rafal.Gaweda
in reply to: dziub7

Stephane,
i don't understand why its not converged, first time when you send me the model,

you find results.

I see the diagram is still accelerating, I expect such behavior during several time, but should

stabilize after this time, Im looking for the value when it is stabilized. I tried the same analyse during 30s, and it still accelerating, but not much.

 

As far as I undestood you \ we got very high accelerations in this model that's why we had to dense calculation steps to get maybe more accurate results.

UNfortunatelly such model did not converge.

 

Im doing it during 50s right now but calculations take a very long time!!!

 

I hope you are calculating it with Pdelta.

 

concerning your setting: time step of 0.002s may be too long to calculate, don't you think?

Do we have any choice? This is the setting which MAY lead us to convergence. We will see.

 



Rafal Gaweda

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