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I thought i'd share some work that is going on for a project i am in charge of.short background:2 days before other scheduled work an overheight truck carrying a windmill tower section came through on the interstate and hit the bridge girders. The accident report said that the leveling sensor (responsible for maintaining the set height of the load) was unplugged and that the hydraulics had been slowly raising without the driver knowing it.For the impact repair, we are heat straightening the girder to the extents possible, and replacing the web where necessary. Here's some pictures of the bridge the day after the impact:Girder #1 took the direct hitshowing the deflection of the bottom flange ... a solid 45° or morenotice the torn web at the K-framefrom the westmuch more to come:
Reply:Here's some pics from the 1st day of straightening:to be clear ... i am administering the project, NOT doing the work. I'm the guy that has to sign off on the work and pay the bills.a close up of the web tear at the k-frameafter they trimmed the web prior to straightening. This section of web gets replaced in its entirety so they didn't have to be "gentle" with the torch. Trimming was necessary, though, as the web would overlap once straightened without trimming.here's a picture of the hydraulic jacks they are using to help straighten the girder, along with the biggest come-along i have ever seen. The jacks and come-along are used only to help convince the girder to go in the right direction, they are NOT the major force responsible for straightening. the jacks are loaded to 3,000 psi -- which equates to about 10,000 lbs of force. which sounds like a lot, but it barely moves the flange under pressure, certainly not moving enough to cause plastic deformation, but just enough to help move the girder toward the heat.here's a pic of the come-along pulling on the girder flange before any straightening had begun. the camera was pretty level, so it gives you a good idea of how badly the girder deflected. also seen in the background is the hand jacks.MUCH more to come
Reply:Here's how the work is done:Find the highest point of the girder and heat on the side in the direction in which you wish the metal to move.Much more art than science.to shrink the flange, heat in a wedge pointing in the direction you want it to move ... that is to say, heat wider on the side that needs to shrink the most.then let it cool down and repeat.the specs call for the temps not to exceed 1,200°F, but the hottest i saw them run was 800°F or so. the web is only 5/16" thick, so going hotter than that really doesn't do much good. Also calls for everything to be heated in a single pass and allowed to cool to less than 250°F before reheat.on day two our weather tanked and with the outside temps in the low teens and wind-chills below zero, they were able to reheat in about 10 minutes.... of course they had to warm up for a half hour or so after each pass, so there was no chance of them getting after it too quickly.MUCH more to come
Reply:Who pays for the damage and subsequent repairs?I really have no idea what I am doing.Two Shop Cats (not Bobcats...real cats)Miller DialArc 250 AC/DCScratch-Start TIG SetupMIG 175Plasma CutterO/A
Reply:Going into this, i had a hard time believing that you could straighten a girder with this much damage ... but the right guys can get it done ....Day 1:Day 2:Day 3:Day 4:
Reply:Day 5:Day 6:that brings us to today.but here's a couple more of the bottom flange.they have about 2 or 3 more days of "ironing out" the web and flange.they say it will look like new when they are done, and i have no reason to doubt them.I'll have more pictures in the next couple of days. by the end of the weekend the girder straightening should be complete and the web and stiffener replacements can begin.i'll be happy to answer any questions that i can.this is a fun project for me of course, i'm not the one up in the manlift day after day in single digit weather and wind-chills below zero ...
Reply:Originally Posted by wannab1Who pays for the damage and subsequent repairs?
Reply:i like itbosses stuff:trailblazer 325maxstar 200my stuff:sa 200fronius transpocket 180100 amp Lincoln w/f97 f350 DITKevin
Reply:Why spend a week and a half straightening and then additional time replacing stiffeners when a cut out and replacement could be done in a few days?My name's not Jim....
Reply:Originally Posted by BoostinjdmWhy spend a week and a half straightening and then additional time replacing stiffeners when a cut out and replacement could be done in a few days?
Reply:My assumption would be that they would have to rent big equipment to support the cut sections of the bridge until the repairs are made.Definitely a neat thing to see.
Reply:Originally Posted by turismolover22My assumption would be that they would have to rent big equipment to support the cut sections of the bridge until the repairs are made.Definitely a neat thing to see.
Reply:This is very interesting to see. I'm glad you took the time to document it.I've tried, albeit on a miniscule scale, to point out to members that most shrinking operations require some amount of accompanying force to get the job done. It simply just doesn't magically move, and retain shape, when heat is applied and the metal allowed to cool unrestrained. I've had little success, and hope this will drive the point home.Anyhow, thanks for taking the time."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Cool photos. I've seen a few photos of similar repairs. It's always amazing... and when finished the member still meets the original spec. Thanks for sharing.
Reply:I didn't mean replace the whole girder. I meant cutting out the bent portion of the web and lower flange. At least enough to minimize the straightening needed.My name's not Jim....
Reply:Meborder I gave up hard-party fun like this decades ago - still the memories linger . . .The torches are inadequate by a magnitude,there is no lever-moment to the flange grapple,a 10,000 lbs porta-power is what you change tires with,and - cutting 'to relieve' the web stiffeners - withthree to five Come-Alongs would have eased, and made for a more uniform draw.Albeit a tempory repair, what is the immediate plan for the web-tear next to the bolted splice array?Opus
Reply:great pics. i see this kind of lower flange damage on most of the bridges around here although not as extensive. ironworkers rock!!i.u.o.e. # 15queens, ny and sunny fla
Reply:Great documentation. A really interesting post. Thanks for the info and great pics.
Reply:Up in a man lift with no safety harness? We would have been fired on the spot!Dont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:This is a very interesting post, thanks for taking the time to document and explain everything. As a truck driver I see lots of this type damage to bridges and often see them after the repair, but it's rare to see it done.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Nice work! Been part of a few of these jobs. Changed out a couple of girders, also. Lots of fun. With traffic control on a busy interstate...along with chipping out a studded beam and replacing the 10 feet of bridge deck and curb...you can easily get into two months. Lots of nights, too. POVERTY...is the Mother of InventionMillermatic 211Millermatic 140Miller Thunderbolt XLArcOne 100STS inverter w/TIGThermal Dynamics 38XL Victor Oxy/AcetyleneJancy Slugger Holemaker IIJet 5x6 BandsawNever enough time & sleep.
Reply:Very interesting. Glad you gave us a look. The idea is to shrink the outside of the flange that is furthest from the web? When you heat the outside while it is loaded under pressure it cannot really expand so it compresses the metal either in the heated zone or right next to the heated zone?Very cool. To bad they do not make a light weight vise that could keep the flange from warping or could be used to straighten it.Do you use a giant rosebud heating tip or just a cutting tip?i wonder if you could use an atomic hydrogen welding rig? Sincerely, William McCormick
Reply:Originally Posted by William McCormicki wonder if you could use an atomic hydrogen welding rig? Sincerely, William McCormick
Reply:Originally Posted by OPUS FERROMeborder I gave up hard-party fun like this decades ago - still the memories linger . . .The torches are inadequate by a magnitude,there is no lever-moment to the flange grapple,a 10,000 lbs porta-power is what you change tires with,and - cutting 'to relieve' the web stiffeners - withthree to five Come-Alongs would have eased, and made for a more uniform draw.Albeit a tempory repair, what is the immediate plan for the web-tear next to the bolted splice array?Opus
Reply:Meborder - this is very interesting stuff and still directly applies to the small scale stuff I do on occasion.(small = micro in comparison to a bridge)Thanks for posting it Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.Originally Posted by BoostinjdmI didn't mean replace the whole girder. I meant cutting out the bent portion of the web and lower flange. At least enough to minimize the straightening needed.
Reply:Originally Posted by CEPUp in a man lift with no safety harness? We would have been fired on the spot!
Reply:Thanks for posting.
Reply:Once the shrinking is done and everything is back where it goes will there be some reinforcements welded in?
Reply:[QUOTE=Meborder;4993251the sides of the man lift are greater than 42" so tie offs aren't required.[/QUOTE]Not anywhere I've ever worked. 6-feet off the ground requires a body harness. Even when in a man basket being held by a crane. The lanyard on the D-ring in the center of your back has to be attached above the headache ball of the crane. 25-feet unobstructed fall to water requires a body harness too.Dont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPNot anywhere I've ever worked. 6-feet off the ground requires a body harness. Even when in a man basket being held by a crane. The lanyard on the D-ring in the center of your back has to be attached above the headache ball of the crane. 25-feet unobstructed fall to water requires a body harness too.
Reply:Originally Posted by vwguy3Once the shrinking is done and everything is back where it goes will there be some reinforcements welded in?
Reply:I worked at a mill that required you to tie odd at 4'. I have seen people move a Man lift without tieing off and get fired. This was a very interesting post. Nice Job documenting the project.
Reply:Originally Posted by Todd496I have seen people move a Man lift without tieing off and get fired.
Reply:A rental house close to me was loading a man lift two years ago off of a truck dock and the air ride settled and catapulted the operator out of the basket so fast he hit the boom and broke his neck.the guy had his harness on with his 6 foot lanierd. Was a great guy.
Reply:Thankyou for posting, I never can resist looking at a good repair of things that may seem to be beyond rescue. Keep it up!I think this says it all about man lifts, catapults, and stupidity. Mostly stupidity.
Reply:Frank Marlow's book "Welding Fabrication & Repair" has pretty good info on flame straightening.
Reply:Originally Posted by CEPUp in a man lift with no safety harness? We would have been fired on the spot!
Reply:Originally Posted by docwelderhow times have changed. back in the day we had no man lifts and tying off was mostly an option.
Reply:Originally Posted by CEPOh God I guess! Belts were used to position you to work. I think it was in the mid 1990s they started pushing the full body harness. Never did like something biting me in the nuts!
Reply:Originally Posted by docwelderi still have my old a.b. belt from the 70's. those were the day's when tying off meant just that.
Reply:Originally Posted by CEPRemember these days? How many times have you done this?
Reply:Originally Posted by welderjNot even if you knocked me out cold and tied me on yourself. I'll go as high as you want as long as I can keep one foot on the ground!
Reply:Originally Posted by OPUS FERROMeborder I gave up hard-party fun like this decades ago - still the memories linger . . .The torches are inadequate by a magnitude,there is no lever-moment to the flange grapple,a 10,000 lbs porta-power is what you change tires with,and - cutting 'to relieve' the web stiffeners - withthree to five Come-Alongs would have eased, and made for a more uniform draw.Albeit a tempory repair, what is the immediate plan for the web-tear next to the bolted splice array?Opus
Reply:Originally Posted by MeborderAttachment 910411
Reply:Originally Posted by William McCormickIf the manual Porta-power or electric porta-power, pump goes to 10,000 psi then that ram is going to output about 100,000 pounds of force. If the bore is 3 1/2". It is the number of square inches created by the bore diameter that creates the force. 10,000 psi times the square inches on the face of the ram inside the cylinder is what determines the force. The reason they underrate, the larger cylinders is not because they will not follow the formula of hydraulics. Rather the problem is that when you jostle 100,000 pounds, it creates forces exponentially greater then say a 1,000 pound load. So although the ram/piston will easily lift the 100,000 pound load it cannot safely carry that weight under a load, and the natural jostling, breakage, slippage, and hammer effects in the real world. The formula is radius times radius times 3.14/pi to get the square inches and then just multiply that number by your working pressure. Sincerely, William McCormick
Reply:The canopenerhttp://11foot8.com/
Reply:Originally Posted by Meborderthey are using 2-1/4" rams at 3,000 psi. 11,922lbs force, by math.the rams are rated to 10,000 psi, but they are only applying about 3,000. as they heat the pressure will drop, but they pump them back up to maintain 3,000 psi as they go.
Reply:I hadn't seen that one before. The one I remember others posting, in several shots there was a pile of bent bridge girders laying to the side when the next truck hit the bridge. In this one looks like they set up a "buffer" in advance of the bridge to take the impacts and avoid actual bridge damage. Can't say the same for the trucks though. I'd love to see the "buffer" structure that can repeatedly take that kind of abuse..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:That made me think of the line in the old C. W. McCall song "Wolfe Creek Pass" ......Sign says clearance to the twelve-foot line, but them chickens was stacked to thirteen-nine. |
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发表于 2021-8-31 22:16:30