Elevated obs stability?

[JB80]

Sorry if it seems a silly question but it's been on my mind and thought I'd ask.

If you had a raised observatory something that was about 3 or 4 ft from the ground how do you get stability for the pier or stop movement from the floor boards shifting?

Do you just have a huge concrete block raised to that height for the pier or is there some other type of standard construction that would be suitable?

[Scott]

I do not have an obs but basically from a purely construction point of view, you need the pier to be constructed in one piece (from the foundations to the mounting plate). if you have joins in the pier they become the weak spot where movement can creep in. you then need the flooring to have a clearance form the pier to eliminate movement when you are moving around or just movement of the structure (obs). hope this helps.

[JB80]

So basically a super long pier?

I had thought of that but thought there might of been another way about it.

I remember a link Olly posted with guys on platforms 20ft high and wondered how they did it, can't recall the link though.

[Scott]

I'm sure there are other ways to do it but as always, it comes down to money

[JB80]

True that. If money is no object it'd be interesting to see what people come up with.

I guess if you wanted a stable enough floor for a tripod it would mean lots of reinforcing.

[laser_jock99]

The 'standard' proceedure is to solidly mount the pier in concrete and have the pier poking through a hole in the floor boards, such that they do not touch the pier.

I can jump up and down on this floor and the scopes will be unaffected.

There is about 1 foot of pier below this floor but there's no reason that with a robust enough construction it could not be longer.

[JB80]

There is about 1 foot of pier below this floor but there's no reason that with a robust enough construction it could not be longer.

That's what I mean though, just how robust would a pier have to be to cover another 4 or 5 foot, I'm sure there are examples but I can't recall seeing them.

[Peter Drew]

Have as large a cross section of the pier as possible. A 250mm diameter X 3mm wall steel tube would be much steadier than a 150mm X 12mm wall version for instance. In every case, as already mentioned, keep the pier isolated from the floor if at all possible.

[JB80]

I have found a few pics that show what I was thinking, instead of having say a 10ft piece of tube going all the way to the ground it looks like these guys built a concrete box up and kept the pier length down a bit.

I would be a bit concerned of the ground shifting over time but maybe that isn't a big deal.

Pics from this website..... http://www.tivoli-astrofarm.de/htm_e/e_astronomie/e_hubble_observatory.htm