Hello gentlemen,

Is it possible to explain clearly how to model a pipe shoe sliding on top of the loading flange of a spring can support with friction? The sping can itself is welded or bolted onto structural steel.

I read Caesar II Application Guide section 4-18 and could only find answer for spring can sliding on steel. I searched this forum and could only find one related post.

My understanding how to model this is as follows:

If we do not model the spring height:
Node 5-10, zero weight rigid (shoe height)
Node 10 spring Cnode 15
Node 10 X Cnode 15 (why?)
Node 10 Z Cnode 15 (why?)
Node 15 +Y Mu 0.3

Do we need rotational restraints between node 10 and Cnode 15?
Do we need any other restraints for Node 15? and why?



If we model the spring height:
Node 5-10, zero weight rigid (shoe height)
Node 10 spring Cnode 15
Node 10 X Cnode 15
Node 10 Z Cnode 15
Node 15-20, zero weight rigid (spring can height)
Node 20, Anchor (because the spring is welded to steel)

Which Node the friction go then?


Please help.

Thanks,

Mike

I guess you can do something like in the attachment.

There are a lot of things you can do with Caesar.

Regards,

In fact this second model is more refined and maybe the correct way.

Advantage is that you can estimate the bending moment on the spring can baseplate.

Regards,

Hi Dan,

Thank you very much for your reply. Your second model makes a lot sense.

However, I notice that you did not input friction factor 0.3 on the guides you put on spring loading column. Is there any reason? The friction factor there will affect the vertical loads on the pipe.

Thanks,

Mike

My model is an approximation. I normally do not use friction in guides. There are also gaps in the column guides, but I didn't model. If you insert friction you will see that the hanger will have about 0 vertical movement. I do not know yet why but it does not reflect the reality, so better not to use friction in the guide. You need to test further until you will reach confidence in the model.

Best regards,