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Old 04-09-2013, 07:01 PM
Portable Welder Portable Welder is offline
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Default How do you strengthen a H- Beam

Question: Lets say I have a 8" H-beam in my basement and from one post to another is 14' but I need to move one of the posts over 4' for my new pool table.

How would I go about strengthening this beam ( This is a hypothetical question.)

Keep in mind the beam already sits low so we cannot add to much to the bottom, maybe a 1/2" lower but no more than that.
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Old 04-09-2013, 07:25 PM
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cross braces. Basically picture many X welded in. The only problem is I would not recommend welding on it if it is supporting a load as it will certainly flex the other way when you are done..

The other thing is to pre stress the beam if it is not installed yet but putting a small jack in the middle and weighting both ends then put the bracing in..

Some would also suggest putting or sandwiching a piece of channel into it.

Or boxing the outside with plate..
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Old 04-09-2013, 07:31 PM
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Get you some bar stock and lay it along the web using LOTS of smallish bolts. Might fishplate both sides.
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Old 04-09-2013, 07:32 PM
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I would box in the ouside of the beam after adding a post to support the weight while welding so you don't flex the beam from the welding, like Jen said.
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Old 04-09-2013, 07:34 PM
Portable Welder Portable Welder is offline
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Allessence, You are right you might want to have a temporary support in the center but you cant push up in the center too much because there is a tile floor above and you want to minimize cracking.

Keep in mind there are a couple of ways to add strength but I want to know what way gives the most strength per lb of steel used.
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Old 04-09-2013, 07:39 PM
Portable Welder Portable Welder is offline
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Milo and shop monkey, That way adds strength but not the most per lb of steel used.
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Old 04-09-2013, 08:19 PM
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to increase strength of a beam you want to have as much material as far from the neutral axis as possible. so either increase depth of beam, or add material to the flanges. the problem with adding to the width to the flanges is that increases the likelihood of lateral torsion buckling
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Old 04-09-2013, 09:37 PM
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I got this one fellas...


Cut a hole in the pool table where the post will be.


Most strength per steel used...
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Old 04-09-2013, 10:00 PM
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Quote:
Originally Posted by Portable Welder View Post
Milo and shop monkey, That way adds strength but not the most per lb of steel used.
Guess I will have to disagree with you on this one. Boxing the flanges will give the most strength. More than fish plating the web or adding material to the bottom flange of the beam. However, you may not need to do anything but just move the post. Depends on the vertical load of the beam where it is and where you want to move to.
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Old 04-09-2013, 11:17 PM
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Quote:
Originally Posted by milomilo View Post
Guess I will have to disagree with you on this one. Boxing the flanges will give the most strength. More than fish plating the web or adding material to the bottom flange of the beam. However, you may not need to do anything but just move the post. Depends on the vertical load of the beam where it is and where you want to move to.

I agree, you need to do some calculations on the beam and what it is supporting. It may be that the beam is over sized enough and you can just move the post. Another thing to look at is this; when learning to weld pipe you are sometimes asked to test by welding a branch tee that is offset inside a box, this would be a 6g-r (restricted). You may want to just put the table against the post and learn to play around it, that way you will be more well versed when playing on a table with no restrictions.
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