just a little weekend work

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so an older ag mech major (my degree) came by the shop about 2 months ago loking for someone to weld for him. well i jump at the opportunity and since then ive been helping him build his 45x80' steel building which will be his shop/apartment.we bought all the rough materials and built it all from scratch, no precut or preformed pieces. everything welded with a ranger 225 about 120 amps with a 5/16 7018we used 12x19# ibeam for rafters and supports and 6" square tubing at 1/4" wall. then 1/4" 6x6 clips welded to the rafters to hold the c-perling.even dropped below freezing a few days and had to work in the ice (east texas ice)the first few pics are only showing 4 of the 5 rafters/supports built. the last pic is the completed frame - minus a few c-perlingshere's the equipment we used to square the building up with the slaband because of the coldweather and constant rain recenetly, my boots have taken a beating.I break things for a living...
Reply:Nice job. Thats what I do at work, fabricate columns and rafters, but no stick welding, all mig. Why are you using such a big rod, (5/16), 1/8 or 5/32 would be sufficent.Merry Christmas
Reply:Looks good.Only 120 amps with 5/16" 7018 ????  Should be at least 300 amps!MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:I think he means 5/32?? Even then thats cold.
Reply:Some things just don't look right to me in the picts. I'm looking at the big 12" columns and then the tiny 6" ones supporting the same roof loads. I'm also looking at the rafter / column conetctions, and they just don't seem right. It's been too many years since I did my structures classes and the rest of my Architecture classes, but somethings just don't quite add up that I can put my finger on..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:You will need to add angle iron braces from the bottom of your rafter beam out to the purlanes. Every other purlane should do.On a weld up it makes a much stronger building and doesn't need the angle braces if you butt the purlanes into the rafter I's. But still use the clips of course. And you should have done all your wall framing first squaring the building as you went. If you had you wouldn't have needed all that equipment to do it. Just some hints for when you do your next building.
Reply:thanks guys!, yes your are correct 5/32, not 5/16.I break things for a living...
Reply:120 amps is to cold for 5/32 7018. Was the amps a typo?
Reply:The 6x6x1/4" tube steel columns will take more of a load than the 12x19 beams.  It's the stress at the top of the columns connection with the beam.  Ever look at a pre engineered building's framing?   They use what is called a "bent beam"  The column and the 1/2 of the roof span beam act as one.    The stress is moved from the center span to the eve, at the bend.  That is why this point is always the widest/strongest.  If you set a beam on two columns(as shown) then the beam for the full span must hold the load.  The 12x19 can't  make that 45' span and hold a proper load hold.  You really should run you plans past an Structural Engineer.  What you may have to beef up is better than picking it back up.  You have put a lot of work in this job.  Just take one extra step to protect it.
Reply:Quick, I see what you meanI'm not a structural guy, but I do know the tendancy of a wall to want to blow out from the roof load.  It's not a true vertical load.  It wants to bow the walls outward.I would imagine the compression on a pitched gable roof would magnify the tendancy.  Or maybe the camber is benificial, the upward bow taking stress in compression before it transfers it to the column.  Now you know how much I don't knowI've seen the thicker curved pieces on buildings at the wall.  I assume the thicker member is an attempt to transfer the roof load in a more linear force (downwards, instead of out)."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Well, somebody has got to have some money that iron ain't cheap...... and you texan's don't know what cold is...... come up here -Mn.-
Reply:Farmersamm, when the 12x19 beam was pitched, it made it into a "bent beam" so the stress will go to the ridge joint.  Since the joint is not beefed up as a bent beam would be at this point it is no more stronger than a 12x19 spaning the 45' that can't span 45'.  The outer wall columns will push out. A Structural Engineer can show him how to add support that works with what he is built. ( I hope)
Reply:I'm looking at the pics and listening to the comments and can see the points you guys are making on the outward forces. Since I'm planning a re-roof project (on a brick building) with 33' metal trusses in the future,I'm paying attention to the concerns being voiced here. I have seen metal framed buildings with adjustable tension rods running from one side to the other,so I assume that's what they were for. If something similar was attached from one rafter bottom to the rafter bottom across from it at every main rafter,would this prevent the spread you are speaking of caused by the roof load? I'm thinking either large rods (sucker rods) with maybe an adjuster turnbuckle in the middle or perhaps a large cable with the same turnbuckle adjuster in the middle(or at one end).I had given some thought to the outward forces being voiced here and that was the thought I had about how to counteract those forces... Would that work???Mines 90' long with peaked web trusses every 10-12 feet otherwise similar to the pictured structures metal Z's with a metal roof setting on a 16" thick brick/block wall.I'm not looking for legal engineering advice ,just an educated thought on if that sort of addition would prevent the spread your talking about effectively...there seem to be some very knowledegable answers,so I'm sure someone knows.Thanks and perhaps it might help the OP to resolve any issues he might be having along the same lines.
Reply:mudbugone   You get into the world of a Structural Engineer real fast with this one.  One thing leads to another in this type of support.  The bottom tension rod you are talking about is used at times.  It must be strong enough to hold the force but the Beam/truss above must then hold the loads now being applied to it.  You kind of moved the loads around with the bottom cord added.  You are making someting like a framing truss now.   On some large clear span pre engineered buildings the footings are tied together from one side to the other, underground to support the outward push.  The largest I ever worked on was 200' clear span.
Reply:I knew that,but at 30' on mine or even at the 45' of the OP... the load with tin roofing material shouldn't be too great ...Should it?My building actually has 8" steel posts 12' tall every 15' down the center already that I could extend to the ridge line for additional support if I have to. I would rather not,since I want to eliminate some of them to open up the floor space. I was going to place an I-beam between two of them with a trolly on it and build a rotating boom on another one with 360* rotation. It really wouldn't be to bad to utilize them for additional support if that makes the most sense from a structural standpoint. It might be simpler to just utilize them instead of trying to open up the floor space.
Reply:Mud PM sent..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:mudbugone,  I don't know what you have for wind or snow but with a standard 30 lb PSF live load at 30' span and 15' bays. That comes up to 13,500 lb per beam load. You may have more or less but the tin roof is just part of what it must hold up.
Reply:The steel trusses I have resemble these, http://www.prairiefoam.com/gallery-i...p?aID=2&cat=14 (you have to click on the small pic) , although these appear to have a steeper roof than the ones I have,the design is similar.They were originally used as chicken house trusses and were placed 10'-12' apart with 2x4 purlins spaced on 2' centers and were originally for a 40' clear span. They bolt together in the peak and I was going to cut them down (at the center)  to cover a 33' span(30' inside) They have 7-8' 'legs' which I was going to eliminate and mount the trusses on top of the 16" thick brick/block wall. Most of the re-use of these I've seen involved 2'-4' concrete pilings or a chain wall with the legs mounted on top of them for use as hay barns or general barns. Maybe I'm missing something structurally,but there doesn't seem to be much engineering involved in the ones I've seen erected ...more like putting up an erector kit,but they are factory engineered trusses.I did not mean to sidetrack this thread and didn't expect it to get this complicated...I was only commenting on the questions raised concerning the load stresses that the OP might have to be concerned with and how he might rectify the situation after the fact that the structure is already up.Last edited by mudbugone; 12-22-2009 at 08:04 PM.
Reply:Your pic is of an enginered truss.  A truss that is a bent beam. That truss was made for that use.  It is at it's widest at the eve and has moved the stress to that point. "pre engineered" is the point.
Reply:Originally Posted by Mega Arc 5040DD120 amps is to cold for 5/32 7018. Was the amps a typo?
Reply:Would agree with DSW and Quick - there is some perception of heavy roof on underdesigned walls... And indeed connection between roof and walls just a welding bead...But again - all depends on the loads... May by all it takes 2mm of rain... If they have the permit - means insurance will be paid by the city if this thing collapses... So they are covered... Liked very much Mud's pictures - perfect trusses...
Reply:Originally Posted by smokin_dodgeno typo, thats where we were running it. we were constantly having problems with blow-through, 120 was more than sufficient for the structure. its only 1/4" metal - welded on both sideswe had a rod stick every now and then, but the structure is bullet proofjust as clarification, i didnt design the building. i just did the welding. the plans for the building come from our ag. mechanics proffessor (who has a phd) who built something slightly smaller for himself. we just took the plans he came up with and modified them slightly. my professors plan was inspected by the city engineers office, so its not going to break.i know were just a bunch of rednecks down here, but we know how to build a structure that will last.
Reply:mudbugone - very nice building, my internet finally came back up and i was able to load the site.i did have a question though, what are they using as a propellant to spray on the insulation?where i stay in colorado during the summer, these guys were building a house and used spray insulation, using propane as the propellant. well one of them decided to light up a cigarette and BOOM! by by building.I break things for a living...
Reply:Just so there is no misunderstanding...I only posted the pic of the truss system as an example of the type trusses I have..not the building. It just happens to be a site about water-blown foam insulation and as I read up on the stuff it sounds like some pretty good foam insulation. (just dumb luck it was something interesting and maybe useful)This is a link to more particulars on the insulation http://www.prairiefoam.com/about-icynene.php  I don't think it uses propane as a propellant (that must have been quite a shock-LOL)Go to the site and there is more info in the left column for anyone interested in such spray on foam insulation.
Reply:my apologies mudbugone, i didnt read the whole post, im somewhat bad about skimming. im going to give that site another good look and seeI break things for a living...Mudbugone,  One in a 100 inspectors I have seen on the job "know" what they are looking at.  If you read the permit anything they missed or OKed is not their falt if it fails, it's yours.  A lot of towns only use the permits for $$$.  I have had 1 job delayed 3 months to get a permit.  Then when you called them for an inspection it took 2 weeks for them to come out, each time.   But build it wrong and someone gets hurt.  That is not an end to a good day.  Then "up north"  we have these things called lawyers.  They are like flies.  But your not alone  http://www.texaslawyers.com/coomer/e...alpractice.htmThey run ads looking for this, even down south.
Reply:Originally Posted by QuickIf you read the permit anything they missed or OKed is not their falt if it fails, it's yours.