Adam AP Mach 1, Rob Miller TRI36L, Celestron 8" Edge HD Hyperion 17mm, Celestron 40mm Plossl, TMB 7mm & 9mm WO 66, Lunt LS60/B1200 PT, CG-5 Clone STF-8300m Pro Package, Honis-Modified Canon XS, Un-modded T1i, SSAG, TSOAG9, SX LodestarLackawanna Astronomical SocietyMy Astrobin
12.5 " F5.6 Homemade Dob , mirror ground and figured by myself 10 " F4.0 LXD55 Meade 6" F8 Homemade Dob , mirror ground and figured by myself , Sears 60mm x 900mm Refractor
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Quote:An acetylene torch can also be used to bend and cut rebar. Heating it up to a nice red makes it easy to bend - even right angles. A cutting torch can be used to cut it.
Quote:Quote:An acetylene torch can also be used to bend and cut rebar. Heating it up to a nice red makes it easy to bend - even right angles. A cutting torch can be used to cut it. Heating rebar is not a good practice.
Ceravolo 300/Paramount ME FLI PL16803/ FLI ML1001 Awesome dawg
AT6RC; C6R; 8" R200SS; 10" SNT; RV6; PST Vixen GP + Starbook-S Warped LXD55 G11 Gemini-1 & DSC Gone! HGM-200 Gemini-2 Orion Starshoot DSCI2; DFK 41AF02 Sky Commander 4 SkyShed POD XL3 14.5" f5 folded Newt Finished. Now in storage. Mount for 14.5" Portable obs on 7ftx16ft utility trailer wi 8ft dome Trailer Plans Approved, Jig Built! http://cleardarksky.com/c/MCAOobMDkey.html
Dark Arts Observatory - Brockport, NY - Skyshed POD XL5 with iOptron iEQ45 Mount
Scopes: C8, C5, SV110 ED, EON-72 ED, ST 80, ATRC6, Megrez 90
Meade LX200 10" f/6.3 Classic
Celestron Nexstar 8SE
Celestron 90mm Mak
Meade 90mm f/8.8 Refractor
Celestron CR-150-HD6 ,6" f/8 Refractor
TASCO 60MM X 900 MM Refractor (My first scope that my wife gave to me for Christmas in '91 , still have it.
Celestron CG5 Advanced Mount
Celestron Bino Viewer
Orange Zone 10'X12' Roll Off Roof Observatory Southeast, South Dakota
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Quote: I would question the real need due to lateral loads and frost, since rebar is not required, nor used in foundations our houses, here in the northeast.
John in NW Arkansas
Quote:Hi Bill:Quote: I would question the real need due to lateral loads and frost, since rebar is not required, nor used in foundations our houses, here in the northeast. I'm not sure where you're getting that information. I'd check with your local building inspector.I'm also in the Northeast, near Rochester NY, and rebar is required in foundation pours here. You're absolutely correct that side loads in a basement are much larger than in a pier. In our climate, you simply could not pay me enough to build a house on top of poured concrete basement walls that have no rebar.In fact, you can look up your (Massachusetts) building codes online. Your state has links to the ICC code site because that's what they use. Check out this page for foundation wall specs:http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_4_sec004.htmScroll down to the section for concrete foundation walls and you'll see the required spacing and size for reinforcing bar.As Tim points out, it's cheap and easy to add rebar to your pier. Do you really want to take the chance of having to dig up a cracked pier after an observatory has been built around it?-Dan
Quote:Dan, Tim,Thanks. I'd heard that rebar saves you from "bad pours". I would question the real need due to lateral loads and frost, since rebar is not required, nor used in foundations our houses, here in the northeast. If there were ever a problem with lateral loads, and frost, it would be in the foundation of a house, and less so in a pier.I'm not trying to be argumentative (and I'm sure this will bring nasty comments), but it seems to me that people put in rebar simply because "its always done in large buildings". Indeed, I asked one of my fellow club members why he put rebar into his pier and he said "it makes it stronger".I'm just trying to determine if using rebar is a myth, or a real engineering requirement.
Quote:... Rebar is cheap and easy to install and it just doesn't seem worth the risk to me to leave it out.-Dan
Quote:Wow ,looks as though someone came here looking for an argument.Do what ever you have to to get the job done.Clear Skies.
Quote:Again, thanks everyone for your comments on rebar. But, I think my wife and her family know what they're talking about when they say its "absolutely not needed".I know, you'll tell me I'm wrong, I don't know what I'm talking about, yada, yada, yada. But no certified building engineer has yet told me that I need rebar in a pier that is only taking compression loads. I'm not talking "you think" or "it's always been done this way", or "it's easy so do it anyway", or even "I think this is what code says" (even though you don't have a certification), I'm talking "I build things day in and day out that don't fall down". And my wife's family having been doing it for 40+ years, so I'm going with them.For those who say this is wrong, what have you built? Where do you get your expertise?
Quote:I see two different questions here. "Is it required by code?" and "Is it beneficial?" Obviously there are no code requirements for telescope piers. So, the question is "Is it beneficial?" You asked that question in an earlier post, so I didn't think I was contradicting your knowledge. I don't doubt your wife's knowledge of your local codes, but when she says they are absolutely not needed; does she mean by code or is she saying there is no benefit to reinforcing concrete?
Quote:I have a concrete retaining wall beside one of my buildings. The reinforcing rebar is visible and the only thing that's holding it together. Heck, that's probably true of half the bridges in PA.
Quote:Sure with a pier, it's probably overkill. Some people build them to last 50 years. Some build them to last 1000 years. Does that many there is a benefit?
Quote:The discussion is around the other kinds of loads that can occur on a telescope pier *besides* compression loads. The primary one is frost heaves, and a less likely load is soil migration, both of which are highly dependent on the specifics of the site such as slope, soil type, drainage, etc.I have close to a mile of fencing on my farm, which has been in the ground for over 20 years. the majority of those fence posts are in position pretty much where I put them. But in a few isolated locations, the posts are pulled up to a foot out of the ground and lean every which way. This is due to frost heaves that only occurred in those locations. I could put a pier in the ground in most locations on my land and never have a problem with it at all. But, if I had put it in one of those particular locations, it would certainly experience substantial side loads - not just compression. In that case, having a proper footing and rebar will make a difference as to whether it survives or not.Your particular pier may be fine without rebar and never experience a problem. But it's a matter of how much you want to take that risk. Again, putting rebar in is simple and cheap. Taking out a damaged pier with an observatory around it is not. I personally would not go to all the trouble of making a pier without the added insurance of rebar in it.
Pete Peterson Peterson Engineering Corp. http://www.petersonengineering.com/sky Wishing Star Observatory http://www.peterson-web.com/wish