Torch cutting holes in Web of Shoring wide flange 1

[shacked]

We have a very large hillside shoring project where we are utilizing permanent shoring consisting of W30x173 steel piles placed inside caissons drilled at 10ft O.C. and a shotcrete wall placed in between the steel wide flanges and a shotcrete wall running between the caissons & wide flanges. On the tension face of the wall the horizontals are #5 @ 10" o.c. & will be ran through the web of the wide flange columns.

The contractor asked if he could cut the holes through the web with a torch instead of drilling. I realize that this could be weakening the surrounding steel web due to the torches heat around the holes, but I am just not sure about this.

Does anyone have any experience with this for shoring.

 

[connectegr]

Holes like bolt holes? Or openings, which could be considerably larger.

I am not a fan of steel erectors and torches. In most cases the quality or the cuts could be achieved by a 4 year old. If cuts are clean and corners are rounded. And notches and edges are sufficiently ground to avoid stress risers, then it can be done. If bolt holes are provided. I suggest burning a smaller hole and reaming to the appropriate diameter. If openings or holes are provided in any manner the design should consider the effects on the net section. Burning holes for structural bolting is an approved method. Unless prolonged high heat is applied the impact the HAZ should be minimal.

http://www.FerrellEngineering.com

 

[shacked]

Connectegr thanks for the info.

The holes would allow the #5 ties to pass through the web of the wide flange to tie the horizontal tension reinforcement of the wall together. Maybe it would be easier to weld the #5's to the web of the steel pile instead of passing them through. Although I do like your idea about punching a smaller hole through the web then reaming it out with a drill.

 

[MiketheEngineer]

Not a big fan of torches - though it is done all the time. If you have just a few holes - say less than a dozen - drill them. Start with 1/8'' or 1/4'' and then your final size.

While the welding idea is good - it may just take too long!!

 

[dhengr]

Why not pre-drill or punch or machine burn 7/8 or 1" holes at 10" o/c over the typical horiz. rebar height of the W30x173. This can be done fairly economically in the fab shop or with a few magnetic based drill motors out in the field. You might not use all the holes, and you may have to field drill one hole, at 6" spacing, near the top to place that bar properly. I would not want some torch monkey doing all those holes out in the field.

 

[shacked]

dhengr, this was at the request of the contractor because he said it was too time consuming drilling all of those holes. Ya, I know anything to make their life easier. Basically I gave them 2 options:

1) Weld the rebar to the web of the wide flange.

2) Drill the holes.

It seems like a lot of the time that I spend on field conditions have to do with making the contractors life easier.

 

[MiketheEngineer]

shacked - you think??

 

[hokie66]

I would prefer field burnt holes to welding the reinforcing steel to the structural steel. The welding requires technical knowhow, the torching doesn't.

 

[MAPeirano]

If it "H A D" to be cut, perhaps a whole jig could be made (and approved by you) and a plasma torch could be used along the inside edge of said whole jig.(You'll have to oversize the whole by the 1/2 the width of the plasma cutter tip)
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Since you're allowing the drilling, why not make it more accurate and faster? Even the heat from drilling will have more affect on the surrounding metal than the 'fast cutting' plasma torch....and the Whole Jig can likely make you penetrations more accurately than drilling can...due to typical accuracy we see when a man gets tired of holding a large drill all day.
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This would help vouchsafe that the wholes were consistant within your comfort zone, and the plasma torch would provide almost no distortion to the surrounding metal...even compared to the drill bit method. Also, the poor fellow that is cutting these holes would find that the plasma / jig method was easier than the torch or the drill... more accurate than the drill.... and faster than either.
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Plasma Cutter - Quick / Easy / Fun / Accurate
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[stierman]

I've been working on several projects of recent that utilize 3/8" through-plates in HSS. We have found the above mentioned jig and plasma cutter has been working out very well.

Beats setting up hundreds of parts in a milling machine!

 

[NS4U]

I am wary of torches. If they do cut it with a torch I'd make them smooth it out with a die grinder.

The torch is going to leave notches that will allow for crack initation and stress concentrations in the web. Depending on the loads this may be bad.

 

[Once20036]

Have any of you seen plasma cutters being used in the field?
I've suggested it a dozen times to a dozen contractors, but nobody has ever followed up on it. I haven't been able to figure out why they would be so reluctant when it seems to me that it would be quicker and easier than mag drilling/burning/etc