ICEINSPACE
Most Read Articles
Moon Phase
CURRENT MOON Waxing Crescent
7.5%
The Sun Now
Time Zones
Sydney*
12:52 am
Perth
9:52 pm
Auckland*
2:52 am
New York*
9:52 am
Paris*
3:52 pm
GMT
1:52 pm




Go Back   IceInSpace > Equipment > DIY Observatories

Reply
 
Thread Tools Rate Thread
  #1  
Old 02-03-2017, 08:22 AM
stefang's Avatar
stefang (Stefan)
Registered User

stefang is offline
 
Join Date: Dec 2014
Location: Willoughby East
Posts: 95
Alternative to Concrete Footings - A Case Study

Hi IIS'rs

Well a year in planning and research, the time finally came during the week for Nicky & I to begin the install of our pilot observatory. When researching IIS, CN, AM and a plethora of individual observatory sites, we kept seeing again and again, a reliance on the use of concrete for Observatory structure and Pier footings.

Its 2017, and I couldn't help but think there was a better way. While trawling youtube I found a video showing the installation of a wind turbine mast on Kangaroo Island here in Australia.

Sure enough no use of concrete for the mast footing, but something different.

I investigated more and found the Australian company that supplied the footings for the turbine project, - without concrete.
http://www.surefootfootings.com.au/

After speaking to them, and subsequently 4 different teams / customers that had utilised them for everything from house foundations building, light masts at sports grounds, wind turbine masts etc I bit the bullet and purchased some units.

We wanted to be sure that the footings would be vibration dampened, as well as free from any sort of harmonic vibration, and these fit the bill given their proven installation history working with Wind Turbines.

The observatory was to be located in a rural area, and we didn't have time for a soil test, so we figured we would have to experiment. All that was required was a 1800w Jack Hammer, 2Kw portable generator, extension cord, post attachment, and some elbow grease.

Oh and about 1 hour of our time for Nicky & I to get the whole job done!

We decided on 8 x SF 150 units for the Obs (4 x Walls and 4 x Roll Off - Roof Trusses) and 1 x SF500 for the pier footing. Each unit utilises 1600mm 2" posts for the driver posts. therefore my footings would be at least 1.6m deep per post, and generating a root ball of approx 3m diameter of stabilisation and security. The Obs walls and Floor are independent of the Pier Footing and Pier to remove any vibration or interaction between the two assemblies.

We opted for the SF 500 Pile Cap unit for the pier footing as it has to secure a Pegasus Pier as well as 160kg + of Mount, Telescope and imaging payload. The 500 units are rated for Up to 330kN. the SF100 Pile Cap units for the wall joists and Roof truss assembly are rated for 110kN. These footings are also removable, which you cannot say for concrete.

Each footing has a leveling plate so we could raise or lower the structure depending on the topology of the Obs site, or alternatively based on the Pier height required.

Step 1 - Attach Pier to SF500 and position. We used a Digital and an Analogue compass to make sure the footing was facing as close to true south as feasibly possible.

Tap 4 x posts in on corners with a mallet and get your jack hammer. Drive each corner in equally, checking the levels of the pier on the way. A laser level is handy here as well as a trusty square level.

Step 2 - Once all 4 corner posts are 1 foot from the base drive all the remaining posts in.

Step 3 - Remove the Pier, and drive the last remaining post straight down in the centre of the Plate for Torsional stiffness. The SF500 has 13 x 1600mm post securing the Pier into the ground.

Step 4 - Drive all posts flush to the guide tubes and Tek screw them in place. Each guide tube has 3 tek screws to secure the posts once driven in.

Step 5 - Reinstall the Pier on top of the SF500 plate, level, and you are done.

Step 6. Repeat as necessary for the other SF150's. these only have 4 posts each as they are load bearing for the Roll off roof truss assembly and walls for the Obs.

Lessons Learned.
1. Rock : Our greatest fear was hitting rock and finding that the 1800w jack hammer which we got from Bunnings wouldnt cope. We did discover though, that when we did hit rock (which happened 7 times), all we needed to do was give the post a good whack with a sledgehammer to break the rock, and then continue driving the posts in with the Jackhammer. We figured this out after struggling with the first 3 posts and realising we could be here all day!

I do believe at one point I exclaimed that the "instructional videos on the SureFoot website were BullS%$!" and there was no way we would get this done in an hour. We found the solution with the sledgehammer.

2. R&D : Dont be afraid to experiment. Everyone one we spoke to said to use concrete. The issue was that by the time you add up the cost for the concrete - especially of your obs is in a remote location, add in the formwork, add in the curing time etc we just found it was both time and cost prohibitive compared to our proposed approach.

3. Cost. I think all in including delivery to Sydney metro I was up for $700+ dollars and an hour of our time to install.

4. Next time: I would definitely recommend this approach, but would recommend a bigger jackhammer with more juice.
Attached Thumbnails
Click for full-size image (IMG_20170227_144515_small.jpg)
91.5 KB304 views
Click for full-size image (IMG_20170227_115857_small.jpg)
73.3 KB286 views
Click for full-size image (IMG_20170227_114110_small.jpg)
80.8 KB289 views
Click for full-size image (IMG_20170227_093021_small.jpg)
94.6 KB282 views
Click for full-size image (IMG_20170227_090132_small.jpg)
175.8 KB267 views
Click for full-size image (IMG_20170227_095732_small.jpg)
25.7 KB273 views

Last edited by stefang; 02-03-2017 at 08:34 AM.
Reply With Quote
  #2  
Old 02-03-2017, 08:47 AM
bojan's Avatar
bojan
amateur

bojan is offline
 
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 4,934
This is most interesting !
BTW, 4 years ago I just drilled the ~30cm diameter hole in the ground, ~75cm deep, for my temporary pier foundation and filled it with concrete.
The expectation was that it would serve the purpose better than tripod, but not nearly as well as traditional, 1 cubic metre concrete slab... but I was wrong
Since then it didn't move a bit - I did pole alignment once, checked it every year but never touched it since, and it is still OK.

So, those "pins" in the ground may behave in similar fashion... if not better.
And they are way quicker to install.
Reply With Quote
  #3  
Old 02-03-2017, 09:19 AM
glend (Glen)
Registered User

glend is offline
 
Join Date: Jun 2013
Location: Lake Macquarie
Posts: 4,073
Great write up and innovative approach Stefan. Not sure i would want to try and remove all those pipes but then concrete is the same in that regard. It took me days to dig the footing hole for my pier, by hand, so any approach that saves my back looks great. Next time, if there is one. Thanks
Reply With Quote
  #4  
Old 02-03-2017, 09:53 AM
traveller's Avatar
traveller (Bo)
Not enough time and money

traveller is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 1,971
Good to see it in action Stefan,
I posted this same video clip I saw a couple of years ago. http://www.iceinspace.com.au/forum/s...d.php?t=132835
Bo
Reply With Quote
  #5  
Old 02-03-2017, 12:22 PM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 3,871
Very nice Stefan look forward to hearing how you get on with it.
Reply With Quote
  #6  
Old 02-03-2017, 04:31 PM
Raydar's Avatar
Raydar (Ray Palmer)
Astronomer

Raydar is offline
 
Join Date: Oct 2004
Location: Perth, Western Australia
Posts: 106
Excellent alternative. But if this was used in clay which expands and cracks with moisture levels, wouldn't it also move slightly like the concrete foundations did?

Ray
Reply With Quote
  #7  
Old 03-03-2017, 09:42 AM
clive milne's Avatar
clive milne
Registered User

clive milne is offline
 
Join Date: May 2011
Location: Freo WA
Posts: 1,344
I designed something similar for a pier I built for one of the imagers on this site... You can see the 3d rendering here:

http://i858.photobucket.com/albums/a...ase%2001_1.jpg

The pier footprint can be seen here:

http://i858.photobucket.com/albums/a...ype%2002_1.jpg

Note how the load is directly coupled via tensile or compressive elements (no potentially flexing plates)

And the finished pier (for an AP1600 + Honders) is here:
http://i858.photobucket.com/albums/a...Milne/pier.jpg

I made some footings for 40' shipping containers using a similar design out of 304 stainless, driven in to salty clay. For an experiment I released the jacks with only one footing installed on a single corner to see what would happen. The single footing held approximately 4 tonnes (plus a fair bit of torque). The laser level indicated that it settled approximately 1mm.
It works.. and is a heck of a lot easier than concrete.
Reply With Quote
  #8  
Old 03-03-2017, 05:22 PM
speach's Avatar
speach (Simon)
Registered User

speach is offline
 
Join Date: Oct 2013
Location: Wonthaggi Vic
Posts: 453
wish I'd know about this earlier just poured a 1.3 cu m pad for my pier!!!
Reply With Quote
  #9  
Old 05-03-2017, 09:01 AM
el_draco's Avatar
el_draco (Rom)
Politically incorrect.

el_draco is offline
 
Join Date: Apr 2009
Location: Tasmania (South end)
Posts: 2,068
I've been pushing these and "mega anchors" for a few years now. Excellent product..
Reply With Quote
  #10  
Old 10-03-2017, 08:26 AM
bojan's Avatar
bojan
amateur

bojan is offline
 
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 4,934
I asked for a quote for typical set (pier + pads for observation deck), and it came around 2k$.....
IMO now, this technology may be justified in case someone is in real hurry...
However, the conventional approach may turn out to be cheaper.
Reply With Quote
  #11  
Old 10-03-2017, 11:32 AM
glend (Glen)
Registered User

glend is offline
 
Join Date: Jun 2013
Location: Lake Macquarie
Posts: 4,073
Quote:
Originally Posted by bojan View Post
I asked for a quote for typical set (pier + pads for observation deck), and it came around 2k$.....
IMO now, this technology may be justified in case someone is in real hurry...
However, the conventional approach may turn out to be cheaper.
Yes, i looked as well, in the end I hand dug the pier footing and the post foundation holes, and the cost for just the concrete & reo (mixed from bags onsite) was very reasonable. However, it does take time, and if your in a temporary situation where you may have to remove it, then this ground anchor system makes sense.
Reply With Quote
  #12  
Old 11-03-2017, 05:53 PM
clive milne's Avatar
clive milne
Registered User

clive milne is offline
 
Join Date: May 2011
Location: Freo WA
Posts: 1,344
Quote:
Originally Posted by bojan View Post
I asked for a quote for typical set (pier + pads for observation deck), and it came around 2k$.....
You asked the wrong person ... I could have supplied you with a better system for quite a bit cheaper.
Reply With Quote
  #13  
Old 11-03-2017, 11:01 PM
strongmanmike's Avatar
strongmanmike (Michael)
Woohoo it's clear

strongmanmike is offline
 
Join Date: May 2006
Location: Canberra
Posts: 13,192
Very interesting and intriguing approach, certainly looks and sounds like a very sturdy option. I look forward to checking out the new observatory in May Stefan

Mike
Reply With Quote
  #14  
Old 13-03-2017, 08:27 AM
stefang's Avatar
stefang (Stefan)
Registered User

stefang is offline
 
Join Date: Dec 2014
Location: Willoughby East
Posts: 95
I'm not letting you try to pull out my pier Mike!!! 😀]
Reply With Quote
  #15  
Old 13-03-2017, 02:33 PM
strongmanmike's Avatar
strongmanmike (Michael)
Woohoo it's clear

strongmanmike is offline
 
Join Date: May 2006
Location: Canberra
Posts: 13,192
Ha ha ha, no need to worry, while there was a time once when I could lift and carry a fully laden shopping trolley, or shoulder drive a full 4m3 waste skip to move it from blocking my car in a car park....my strength these days lies soley in the quality of my humour and about all I can lift is a persons spirits now ..so your pier is safe

See ya at Wiruna

Mike
Reply With Quote
  #16  
Old 24-05-2017, 01:17 PM
stefang's Avatar
stefang (Stefan)
Registered User

stefang is offline
 
Join Date: Dec 2014
Location: Willoughby East
Posts: 95
Mike,
might needs your muscles after all. My new mount has arrived, all 65Kgs of it. some lifting expertise might be welcome.


stefan
Reply With Quote
  #17  
Old 25-05-2017, 11:11 AM
Wavytone
Fringe Lunatic

Wavytone is offline
 
Join Date: Jul 2008
Location: Killara, Sydney
Posts: 2,450
Interesting piling idea, Stefan.

Clearly good in hard clay soils or soft rock like sandstone but I'm wondering what happens if you hit something hard like granite or basalt... drill and concrete ...
Reply With Quote
Reply

Bookmarks

Tags
alternative., concrete, footings, observatory

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 11:52 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Advertisement
OzScopes Authorised Dealer
Advertisement
SkyWatcher Star Discovery
Advertisement
Lunatico Astronomical
Advertisement
FLI Cameras and Imaging Accessories
Advertisement
Meade Instruments
Advertisement
Bintel
Advertisement
Atik 16200
Advertisement
Tasco Australia
Advertisement
Astronomy and Electronics Centre
Advertisement