Hi to all,

I'm currently working on an existing system where a lot of hangers and compensators are used. All hangers are at the end of their travel range and thus became normal restraints. My task to get a lot of hangers and compensators out (cause of installation problems. It's too flexibel atm).

What I want to do is to change the system bit by bit until the pipe isn't overstressed. For these calculations it would be nice if CeasarII could change hangers into restraints when they reach their full travel range. I don't want to give these points a displacement cuase I have a lot of different load combinations and each combination should need it's own set of displacements then.

Is it somehow possible to enter a maximum travel range for the predefined hangers? And does the hanger become a restraint when it's at his end? Or are there other solutions?

I believe you could place Y, +Y or -Y restraints on the same nodes as the Spring Hangers and place gaps equal to your travel length. I would build a small test model to ensure the results make sense with what you are doing.

If you know how much travel remains when the spring is installed, you can replace the hangers with a YSPR restraints. With this restraint you can specify the spring rate, the (theoretical) cold load and the remaining travel before "bottom out". You might want to use the calculated installed position to get a number for this remaining travel.
It may be a lot of work initially but it may pay dividends when you start to experiment with your changes.

I was first thinking of Greg F's method too. Would that be OK to do?

The YSPR restraints aren't really workable I think. The client wants to know what happens if we replace spring1 with a normal restraint, what happens when we replace spring1 and spring2 etc etc.
I would need to get the remaining travel for all these cases.

What would be the difference between Gregs method and Daves, seperate that I need to check 2 restraints in Gregs option and only 1 in Daves.

We normally tell people to use the YSPR restraint, but if you know the travel limit you can use the +Y w/gap approach and it will work. But then you will have to remove both the hanger and the gap in the +Y when you replace the hanger with a "normal" restraint.