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The Adventure Begins -- Construction

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#51 1965healy

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Posted 28 January 2009 - 10:21 AM

Hey Andy! I'd consider putting a wide strap around the top of the concrete pier at roughly the level of the bend in the 'J-Bolts" just for safety sake. Mother nature tends to shake things up a bit in that neck of the woods. It may not seem an issue at this point but if you go with a larger mount and OTA at some point it may become one.

I second mikey cee on access to the area under the flooring, better to install a trap door access now than to have to create one after everything is installed and you find you need to get under there. I'm not sure how you were planning to get power and data to and from the piers; I'd be inclined to use three 3" PVC pipes from the warm room to the piers. Use the center one for power with a "T" at the piers to split it out and the outer ones for data/etc to each of the piers. You can use an elbow and bring them out thru floor flanges in front of each pier. I wouldn't just string wires under the flooring since there are alot of little 4 legged critters who like to munch on insulation in your neighborhood.

#52 andyschlei

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Posted 28 January 2009 - 10:43 AM

Karen,

Thank you for the recommendation. I'll put that pvc conduit in. I already had some wires in my truck eaten by little beasties.

I'll also proceed on the strap. Your comments about shaking bring to mind images of concrete columns split with re-bar sticking out after an earthquake. Now all columns on freeways are wrapped in steel.

:thanx:

And there will be an access door. How else to drive away the rodents when they move in? :lol:

Clear skies,

--Andy

#53 1965healy

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Posted 28 January 2009 - 11:58 AM

Andy, link to 12" Strap Clamp.

#54 andyschlei

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Posted 28 January 2009 - 12:49 PM

Andy, link to 12" Strap Clamp.


Thanks Karen!!!

:jump:

#55 1965healy

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Posted 28 January 2009 - 04:11 PM

Andy, put this stuff around the pier top BEFORE you put the clamps on. Order the 6" size @ the bottom of the order form. Use 1 roll per pier. Pipe Wrap

#56 HunterofPhotons

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Posted 29 January 2009 - 12:20 PM

Posted Image

As you can see, there are places where the bolts are visible because the concrete does not cover them entirely. These will be grouted to cover them, and it is 3,000 PSI concrete so it is strong. The j-bolts turn into the concrete at the bottom. Do you think I should add a metal strap around the pier?

Andy,
You can forget about the metal 'band-aids', they won't be of any use if your bolts become loose.
The good news is there isn't much stress on the mounting bolts so, if the bolts are solid now, they'll probably be all right.
For future reference, you need to size the concrete column such that the bolts are placed a couple of inches in from the edge.
I see that you have a bit of 'popcorn' in the column. That means the concrete wasn't worked enough to remove the entrained air. It's easy to underestimate the time it takes to work concrete. Once again, if your bolts are solid now, you should be okay down the road.
The only thing that I would do now is if your bolts are plain steel I would coat them with something to prevent them from rusting. Rusting steel embedded in concrete will expand and break apart the concrete. The fix for that isn't fun.
Your pictured column inspector looks pretty happy with the job, though. <g>

dan

#57 andyschlei

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Posted 29 January 2009 - 12:42 PM

You can forget about the metal 'band-aids', they won't be of any use if your bolts become loose.
The good news is there isn't much stress on the mounting bolts so, if the bolts are solid now, they'll probably be all right.
For future reference, you need to size the concrete column such that the bolts are placed a couple of inches in from the edge.
I see that you have a bit of 'popcorn' in the column. That means the concrete wasn't worked enough to remove the entrained air. It's easy to underestimate the time it takes to work concrete. Once again, if your bolts are solid now, you should be okay down the road.
The only thing that I would do now is if your bolts are plain steel I would coat them with something to prevent them from rusting. Rusting steel embedded in concrete will expand and break apart the concrete. The fix for that isn't fun.
Your pictured column inspector looks pretty happy with the job, though. <g>

dan


Dan,

Thanks for the feedback. The bolts are very solid right now. I certainly will put a coat of rustoleum or other epoxy paint on them. The columns have been grouted since this picture was taken, so there is no path in from the sides for moisture.

I guess the idea I had was that strapping would prevent them from coming loose by keeping pressure on the concrete. More pressure to prevent a wiggle when that inevitable earthquake comes.

And the column inspector had a lot of fun with the bolts. :jump:

--Andy

#58 Project Galileo

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Posted 29 January 2009 - 02:02 PM

Looking good. I can't wait for spring to play with concrete in Colorado. I am glad somewhere it is warm enough to build. You have a fine start. Thanks for sharing.

#59 RobVG

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Posted 29 January 2009 - 10:19 PM

Hi Andy, Since your mounting plate holds the top of the bolts together, and the short leg of the anchor bolt is pointed inwards, it should be ok. Like Dan metioned, If your bolts came loose, you'd have a problem.

Hypothetically speaking, If your problem was serious,you could use a clamp like Karen suggested. I know of one thats a little more heavy duty Here. They come in 6" and a guy could bolt two together for a 12" pier. It would probably be a good idea to slather the afected area with anchoring epoxy before installing the clamp(s).

#60 Mel M

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Posted 30 January 2009 - 02:15 AM

I wouldn't use the bolts for thirty days. I would lube the threads and use a light touch. I wouldn't put any pressure on the concrete with straps.

Mel

#61 andyschlei

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Posted 30 January 2009 - 10:52 AM

Rob -- Thanks for the link to strap. The bolts are quite solidly in the concrete right now.

Mel -- No chance to use them for probably 45 days from now, and the cement was poured two weeks ago. We are still waiting on the steel fabricator for the roof assembly.

In terms of pressure on the concrete, do you mean now while it cures or ever?

Thanks,

--Andy

#62 HunterofPhotons

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Posted 30 January 2009 - 01:00 PM

Andy,
If you really want to obviate the need for future fixes, there's a remedy that's easy enough to do now, harder to do later.
Get or make a tube that's about 4" greater in diameter than your present column and the same height. Slip it over your column and fill the space with concrete. It would be okay to use a smaller aggregate mix and to water the mix down a bit. Then you can be like the guy on Mad comics: "What, me worry?"
As for concrete curing, depending up conditions, it attains about 90% of its full strength in about a month and it's said that curing continues for a hundred years. You don't have to wait that long to mount your pier, though. <g>

#63 1965healy

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Posted 31 January 2009 - 09:11 AM

Andy, one other suggestion for helping to mitigate the effects of the shallow j-bolts. Since I'm not sure what you're going to mount your scopes to in terms of a "plate" this may or may not be something you can try. It should help to distribute the lateral forces on the pier bolts by adding a center point. Just a thought.

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#64 andyschlei

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Posted 31 January 2009 - 11:19 AM

Andy, one other suggestion for helping to mitigate the effects of the shallow j-bolts. Since I'm not sure what you're going to mount your scopes to in terms of a "plate" this may or may not be something you can try. It should help to distribute the lateral forces on the pier bolts by adding a center point. Just a thought.


Karen,

Thank you for the suggestion! I might even be able to implement this with a bolt hole in the bottom of the pier.

:thanx:

#65 andyschlei

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Posted 02 February 2009 - 02:23 PM

I just spoke with the contractor and we are going to pour additional concrete around the existing pier foundation. That will add a couple of inches of diameter. In this case, the rough exterior of the pier will be an advantage.

Thanks again to all for the help.

After some delays, the steel for the frame and the roof is being fabricated and should be set by early next week. Framing after that and framing always goes fast.

--Andy

#66 greg

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Posted 02 February 2009 - 02:56 PM

I would cut that thing off as close to the base as possible , drill into the remaining pier and epoxy new rebar up rights, and pour a new column correctly this time.

Just my two cents

Greg

#67 1965healy

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Posted 02 February 2009 - 03:57 PM

Andy, I'm not sure what your plan is for the "new" pour but I'm guessing that you're either going to "sleeve" the existing piers with a larger SonoTube or "box" them with the corners of the "box" located to provided the greatest thickness where the "J-Bolts" are the shallowest. Unless you plan on going at least about 3 inches oversize all the way around I'm not sure how much strength you'll be adding. You're going to need a small aggregate in a wet mix to eliminate any voids in the next batch. You'll also need to add an adhesive to the mix to help the two surfaces to bond. Acid etching the existing piers wouldn't be a bad idea, nor would "wrapping" the piers with some wire mesh to give the mix something to grip. The addition of some NyconAR glass fibers would help as well to tie the slurry together. The concrete will need to be vibrated to insure that all the air is eliminated. If you do just add to the existing piers you're going to need to look at whether all that extra concrete is going to cause problems with the mount. Is the added size going to hit the counterwight shaft or OTA's at some point in their travel? Just playing Devil's Advocate.

#68 andyschlei

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Posted 02 February 2009 - 06:27 PM

Karen,

We'll be putting a larger sonotube around the existing base and pouring additional concrete into that. We will "rough up" the exterior of the current pier footings and use some epoxy additive to make it stick. We will also drive some spikes into the existing columns to help bind the new concrete with the existing. I'll ask my contractor about the NyconAR, that looks like a good strength additive. We'll be using 3000 psi rated concrete too.

Diameter isn't an issue because these footings end at floor level. I'll be bolting 8" piers to the top of the footings.

Greg, I've got an existing pier with the same diameter footing and bolts close to the edge and haven't had any trouble yet. That makes me comfortable enough to take a mitigation rather than replacement approach. But I do appreciate the input.

Thanks to both of you for your replies!

:thanx:

--Andy

#69 RobVG

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Posted 02 February 2009 - 07:50 PM

Hey Andy, If your going to pour additional concrete make sure you place some reinforcement like Greg said. Remember, concrete only has compressive strength (your contractor should know this)- extra concrete around the existing pier won't help. You need some type of steel reinforcement. Even heavy wire mesh might do it.

#70 greg

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Posted 03 February 2009 - 03:28 PM

Andy,

I hope all turns well for you. Replacement would not be that difficult and would leave you with the same diameter pier that you wanted in the first place. As has been brought out, Make sure the new larger diameter pier won't have any clearance issues with any of your equipment now or any future equipment.

Greg

#71 Timber

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Posted 03 February 2009 - 11:56 PM

Andy,

Just another 2 cents worth. Really just depends on your ability to sleep soundly at night, I tend to worry and would not want to have to go through what Scott K had to do in Oklahoma. Three alternatives;

1. Ignore the issue and hope for the best and deal with whatever problems may develop in the future.

2. Follow Greg's advice and take them out now and reinstall them properly.

3. Don't rely on any concrete veneer to do anything. If you are going to increase the diameter of the piers, don't use paper Sonotubes, use steel pipe and leave them in place with the new veneer concrete solidly contained.

Good luck,

Richard

#72 andyschlei

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Posted 04 February 2009 - 11:08 AM

Richard / Greg,

I'm half way to Richard's #1 option and not worrying about it. That makes the reinforced veneer option OK with me.

Thank you the the input (and RobVG too!).

--Andy

#73 andyschlei

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Posted 16 February 2009 - 05:06 PM

After many weeks of waiting for the fabricator, we've made some progress. The steel for the building frame was delivered today! They were going to mount the steel, but it was raining (no complaints, we need the water) so that is on hold until tomorrow. And I can't stay out at the site to see it being assembled. :nonono:

In any case, here are some pictures. This first one shows the full pile of steel. There are 6 vertical supports that will hold a u-shaped frame for the roof of the observatory. The long beams in the back are the roll-off roof supports, 28' long. All the steel is 4" tube steel. All the steel to meet building requirements.

Posted Image

Here is the detail of the observatory end of the roof supports. You can see the angle iron on the far beam. The angle iron is cut away and moves to a steel bead for the roof in the closed position. This will allow the roof to move down slightly and make a better seal.

Posted Image

Clicking on the images should get you to a larger version of the shot. I'd have taken more of the details but the rain was coming in and it was pretty windy.

If all goes according to plan, framing will start on Wednesday. I plan to be out at the site this coming weekend and expect to see a lot of progress. Framing always goes quickly.

Clear skies,

--Andy

#74 RobVG

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Posted 17 February 2009 - 12:47 AM


That's some serious framing Andy.

Do you have a crane? :grin:

#75 andyschlei

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Posted 22 February 2009 - 11:40 PM

Work progressed well over the past week. The steel was set onto the footings on Tuesday with only minor interference from the rain. The pier footings were expanded and the floor joists set. Now we're cooking with gas....

Here is the observatory, looking to the west. The roof will roll off to the west -- the observatory proper is in the foreground.

Posted Image

After all the discussions and recommendations from the group, the pier footings were expanded to add strength. There was bonding to the existing pier with many nails driven into it to hold the new concrete, and additional reinforcing as well. The pier footings are close to the joists. When the sonotubes are removed, there will be a good 3/4 inch spacing on all sides. The spacers on the far side in this picture are not yet permanently set. You can also see the stairway from the house under construction in the background.

Posted Image

This last shot shows what has given the observatory its first, probably temporary, name. When looking up at the observatory from the driveway, my wife saw this looming frame of steel and dubbed it "Steelhenge." I think this shot taken with dark clouds around it shows why she came up with the name. We'll see if the name sticks as construction progresses.

Posted Image

In my last post, I erroneously stated that the long roll-off beams were 28', they are actually 30' to accommodate the overhangs on each end. I also said that this was all 4" tube steel. It is 6" tube steel. I'm ready for the next major earthquake, in any case. And Rob, they used a Pettibone to lift up the steel.

The main rafters for the roll-off arrive tomorrow. These will be 6" tube steel formed in a curve for the curved roof. We'll be insulating and sheeting the floor, then framing the building out once the location of the main rafters is determined. It's quite an adventure with all the little details.

Thanks for looking. All comments gratefully welcomed.

--Andy


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