Pillar for mounting a metal pier

[fifeskies]

l have an area of raised deck in my garden that has good sky views.

I plan to install an Altair Astro metal pier on the deck for convenient use. 

(the pier will be permanent and have a cover over it, perhaps even evolving to a full mini observatory with a roll off enclosure)

 

I will not be mounting direct to the deck as there will be vibrations as I (and others) move around. As I can get under the deck I will cut a hole in the deck for the pier and create an mounting pillar under the deck so the pier is isolated from vibrations.

The ground below is solid (bedrock) so I am wondering how wide the pillar should be. The pier is 300 wide so I need at least that diameter for the fixing bolts.

The pillar will be around 2.1 metres high and probably a concrete mix into a mould ,I will drill long rawlbolt anchors into the bedrock to secure the column at the base and will use rebar in the actual column to reinforce it. I don't want to build anything too huge as I expect a solid column will be largely vibration free , but it is a high column so it needs to be wide enough not to suffer vibrations.

I was thinking I could use some kind of large diameter drain pipe (agricultural type) as a mould.

 

Has anyone done anything similar , or has ideas as to how big the pillar needs to be.

 

I have a photo from elsewhere showing the pier used by another astronomer on a deck.

I hope to do as tidy a job , but need a high column under the deck to the ground far below.

 

 

I am thinking of some of the kind of pipe shown below for a mould , If I can source an offcut from local agricultural suppliers.

It is available in many sizes up to 600mm diameter, though I was thinking something around 300 or 400mm may do.

Either that or make a plywood mould for the pour and have it flared wider at the base.

The column wont be on view , hidden below the deck , so it doesn't need to be terribly aesthetic , merely functional

 

 

Edited November 29, 2019 by fifeskies