Thread: Dynamic modelling

Started: 2008-09-22 23:52:00
Last activity: 2008-09-22 23:52:00
Topics: SAC Help
Belema Altraide
2008-09-22 23:52:00
To whom it may concern

I have modelled a jacket (file attached) and have performed a dynamic analysis on the structure (extract mode shapes). I have fixed the sturcture dynamically on four corners of the jacket and the topsides 222000. At the base of the structure, there is a central joint 2001 (at EL-180) that has spring values applied on them and these values are:
vertical: 7000MN/.
Lateral: 2500MN/m
Rotational: 8E6MN/radian
Torsional: 4E6MN/radian

I analysed the structure with these applied spring stiffeness values and the 4 joints 21,22,23,24 dynamically fixed in all directions (222222) and am getting a period of 44 sec with the structure rotating vigorously.

I need some help with the following:
1. I am unsure how to apply the spring values from joint 2001 to the four corner joint 21,22,23, 24. At the moment, I assume that I will need to rigid link joint 2001 to the four corner joints?
2. If 2 is correct, I am unsure how to rigidly link the joint 2001 with the spring stiffness values to the four corner joints 21, 22, 23 and 24.
3. I am unsure what fixities I need to apply to the four corner joints.

Your help to the above queries would be greatly appreciated. Please help me asap.


Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses

04:42:44 v.d4df61ad