P-Delta analysis for a very long bar

[Anonymous]

Hi,

My model is a vertical tubular structure (underwater) under sea current conditions.

(weight neglected)

I want to calculate the large displacement going on.

I use P-Delta non-linear analysis.

My current model does converge in the linear mode with strange displacement results (8 km displacement) but does not converge in P-delta mode.

I suppose P-delta to be more apropriate for large displacement. I do not know if this calculation is feasible or my model is wrong in some way.

[Anonymous]

[Rafal.Gaweda]

Model height - 1547m !

[Anonymous]

Precisely.
I precise, it is the height of the system I want to simulate.

A vertical tubular profile, very deep in the water.

[Rafal.Gaweda · Accepted solution]

It is cable like behavior.

Correct settings: generate 20 nodes on each long bar, set Netwon Raphson - see below

I do not know if you made model correctly  - please check FZ reactions.

[Anonymous]

I am doing it wrong: still no converging.

If I am correct:

-> dividing the bar provide freedom and make the "cable like" behavior possible.

-> increase the load increment because we are in presence of very strong loads

-> I do not understand what is BFGS

-> Matrix update each iteration in order to set Netwon Raphson

[Rafal.Gaweda]

My file attached