WT shape material

Date 08-02-2011 16:36 Edited 08-02-2011 16:39

Hi Joe,
WT's can be cut from a WF shape, the dimensions are (usually) half nominal depth of the WF section...ie WT8x13 cut from a WF16x26. Table 1-24 in ASTM A6 (on page 1-120 of the AISC's 13th edition of the Manual of Steel Construction)gives you the tolerances.

edit*
If we buy the WT's as WTs they come in already split except for a few stitches up the middle of the web, so that they remain straight and also so we can run them through our beamline punch. If a WT is added on a revision or something, we find a WF beam in inventory and split it ourselves.

By joe pirie (***)

Date 08-02-2011 16:57

The Dwg called for A WT 20x91.5 it didn't specify a WF cut down. I was under the impression if it was listed in the AISC book it could be purchased
My concern is the excessive amount of camber due to the way they cut the beam. seems they could have tacked some stiffners or like you said left a few areas uncut
every few feet instead of starting at one end and cutting continually to the other.

Thank you for sharing Joe

By aevald

Date 08-02-2011 17:37

Hello Joe, as John stated, he sometimes receives his WT's cut but not completely seperated by the short sections of beam that have been left from the stitch cutting of the centerline. Thus he can process the parts while they are still relatively straight. When they come in cut into two halves there is a thermal contraction of the cut edge resulting in a "camber" condition. If you apply "buttons of heat on the flange centerline starting in the center of the WT and working towards both ends you will likely be able to straighten it out without too much trouble. Also, depending upon how much resulting camber that you have you can space these "heats" either close together or further apart depending upon how much you need to move it. Definitely a bit of a trial and error process, yet, with a bit of practice you/your fabricators will figure it out fairly quickly. Good luck and best regards, Allan

By jwright650 (*****)

Date 08-02-2011 17:51

You can cut that WT from a (Wide Flange)W40x183. Like Allan stated, you have to place a few heat spots along the centerline of the outside of the flange and also on the underside of the flange in the K area to get enough heat soak to actually move the it......Because that thing has a 11.750 x 1.1875" thick flange.

By welderbrent (*****)

Date 08-02-2011 20:01

Joe,

What is the WT being used for?

It may be possible that when placed together with other components and fit up the extra camber could be 'pulled' out of it. Then, while care would need to be taken to make sure it doesn't warp in a new direction, the weld out process would lock it in place so it wouldn't go back to the camber. Granted, it is a fair sized member to pull around straight.

Personally, all WT's I have seen were cut from WF. Even if they came from the manufacturer or warehouse. But fabricators who do it very often know they need to leave a few spots and let it cool back to ambient temp before cutting it loose. Even then it will often move outside of the tolerance.

Have a Great Day, Brent

By waccobird (****)

Date 08-02-2011 21:39

Brent

We get very little deformation and we don't leave uncut spaces in between.
We Cheat
Our Robotic Plasma does a back-step cut through the length of the beam
and with the correct consumables very little heat is involved thus very little warping.
Because of our selection we can only run 36" wide.

Have a Great Day back at you

I am Blessed

Marshall

By joe pirie (***)

Date 08-03-2011 01:49

The WT gets welded to a wf beam on the bottom flange edge with a partial pen 5/8 bevel and a 1/4 fillet on opposite side.
The contractor assures me that they can get it straight im concerned just how much heat there going to have to put on it
to remove 4" of camber. Thank you all for your help Joe

By jwright650 (*****)

Date 08-03-2011 11:28

Didn't say whether charpies are involved or not, so I'm going to assume NOT.....use some 1050, 1100, 1150 tempil sticks and watch the heat cambering process...sneak up on the 1150 and you won't cross the 1200 threshold where things could get out of hand. May take just a few heat spots, it may take several with several in between those and wedges of heat in the web....it really depends on how well the material shrinks and responds to the heat spots, every stick of steel is a little bit different. 4" of camber in 40 or 50 feet isn't too terribly bad, but if the piece is 20 feet long, then you really have your work cut out.

By welderbrent (*****)

Date 08-03-2011 22:28

Hi Marshall,

Good point, but I will bet they used a handheld torch thus magnifing the results because of the temps and slow travel speed. AND, I'll bet they didn't backstep. Even the handheld plasma with magnetic straight edges so as to increase travel speed and cut smoothness would have helped and especially if they incorporated the backstepping. And, for extremes, if one were to leave a few spots and let it cool back to ambient as previously mentioned I would wager you would greatly reduce any warping.

From how he said it is to be welded, if I understood right, they should be able to get it pretty straight in fitup before welding. Then, if there were still a concern, they could go down the 'T' side with a rosebud to relieve it a little. And not even get close to John's concern about the heat. His idea would work as well.

Have a Great Day one and all, I'm having a Great Week. Our 34th Anniversary this weekend. Getting out of town for a few days with just the wife. No kids or grandkids.

Brent

By joe pirie (***)

Date 08-04-2011 11:58

cut with a trac burner on a bevel so they wouldn't have to cut twice. first one they cut from one end too the
other about 4' camber in 30 ' 2nd one they cut after my complaining about excessive camber they left about a foot of solid material
every 6' when they went back and cut out the solid places it still sprung pretty bad not much difference.