12" x 6.5"x 3/8" thick x 41' Residential Basement I-Beam Concerns

[secant]

I have lived in an A-frame house with a basement for 8 years that has a 41 foot long steel I-beam (12" x 6.5" x 3/8" thick) in the basement.

Notice in the picture above that one end of the I-beam sits on a shelf cut into the concrete wall:

Then 9 feet down the beam there is an adjustable steel post support, then another 8 feet down is the second adjustable steel post support, then 3 feet further is a wood wall with 4 "2x4s" nailed together below the beam, then another 4 feet from that is the second wood wall with another 4 "2x4s nailed together, then it run 17 feet before it reaches the end of the house where it is supported on a block wall on top of a wood laminate beam:

Below is a representation of how the I-beam is supported (The two story section of the house runs the first 24 feet, then the one story section the remaining 17 feet):

Two story section of house One story section of house
------------------------------ --------------------------
9ft 8ft 3ft 4ft 17ft
^1^[[[[[[[[[^2^[[[[[[[[^3^[[[^4^[[[[^5^[[[[[[[[[[[[[[[[[^6^

Legend:
each "[" = 1 foot length of steel I-beam
"^1^" = concrete shelf (start of beam support)
"^2^" = 1st adjustable steel post (no point contact)
"^3^" = 2nd adjustable steel post (point contact)
"^4^" = Wood wall (4 "2x4s" nailed together below I-beam)
"^5^" = Wood wall (4 "2x4s" nailed together below I-beam)
"^6^" = Concrete blocks with wood laminate beam (end of beam support)


My first concern is the concrete shelf supported section of the I-beam, in which a cut was made into the solid concrete basement wall to create a notch:

Notice a crack in the wall (has been there 8 years) on the left side of the notched cut shelf and on the right side of the shelf the concrete cutter went wild and cut too far downward. My concern is that this concrete support could crack off easily due to the crack and cut on both sides of the shelf.


My second concern is a 1.25deg tilt/twist of the I-beam that happens to run at 1.25 degrees tilted to the left throughout the entire section of the I-beam below the second floor and half way down the I-beam under the one story section of the house (twist runs about 32 feet). Now the I-beam is 6.5" wide, so a 1.25deg twist ends up leaving the left side of the I-beam 9/64" lower than the right. My question is do I-beams normally have such a twist, and is a 1.25 degree angle considered "normal" and/or acceptable?

My last concern is the two steel supports. The first steel support does not have point contact (like the second steel support). The adjustable section of the first steel support is slightly angled due to the twist in the I-beam, as seen in the pic below:

In the picture above, the I-beam is lower on the left side, and the threaded section of the post is slightly bent/buckled out toward the left. Also not that their is no point contact on the top of the threaded post, and thus since the beam is angled, the top of the threaded post hits on the left side of the contact plate and is gapped slightly on the right side.

Now on the second adjustable steel post, there is point contact (a slug of round metal about 1/8" tall) and there is no bend at all in the threaded section of the second steel post:

What concerns me is the slight buckle in the fist steel post....could this get worse with time (house is 10 years old...twist has been there the 8 years I've owned it). Also, why does it not have point contact like the second steel post?

In summary, does anyone think I should be concerned about the I-beam twist of 1.25 degree and the slight bent angle of the first adjustable steel support, along with the "questionable" concrete shelf cut into the basement wall? I am in the process of placing a wood wall below this I-beam to create some finished rooms, thus I would want to make any fixes before this happens. My thought is that if I place a wood support (4 2x4s nailed together) below the I-beam at the concrete shelf, this would aleviate some of the load at that section. Also, I was going to build a build two side-by-side 2x4 wooden load bearing support walls below the I-beam in the section below the two story part of the house, which would help ensure the I-beam would not twist further with time (plus I need those two walls to finish the rooms anyway...I could even make the left side wall studs 1/8" higher to help fix the I-beam tilt). Would this help, or am I wasting my time worrying about things that are normal for house construction and not of any real concern?

Thanks for your time and input,

Troy

 

[secant]

Forgot to add some information that might be useful:

1. I-beam sits 4" within concrete foundation notch

2. 2"x10"x15 wood floor joists @ 16"OC sit on both sides of the I-beam (house is 30 feet wide and 41 feet long)

 

[AUCE98]

Hire a structural engineer to evaluate your beam and floor system. You have obviously provided a good discription of the beams supports, etc. however, I don't believe it is anything that I would be able to give you a true opnion.

Just in general, if the beam has been there for 8 years I would not think it is going anywhere soon, however I would have a structural engineer asses the situation.

Regards,

AUCE98

 

[UcfSE]

If it bothers you that much certainly hire someone to look at it. 1.25 degrees is a lot of tilt and could happen from off-center load or off-center support like those posts. You could have properly designed and detailed posts installed. That might take care of the tilt, but then it might not. We can't say even from a post put together as well as yours. IMHO I wouldn't be worried about the crack. It may be due to shrinkage and it doesn't look to be in a direction I'd be concerned about. 4" bearing on that wall is probably ok. The hole looks like it was cut sloppy but is likely ok. If it's been there that long you're likely to be all right but the few hundred $ you spend to hire an engineer and sleep better at night could prove to be money well spent.

 

[secant]

I had planned to hire a structural engineer to evaluate the I-beam twist before I enclosed it within new finished walls, I just wanted to get as many comments from this forum as possible to be more prepared. I do think that since the beam has been twisted for at least 8 years like this without any changes, that is a good sign it has "settled"...yet I live in an extreme weather climate in which 40 degree daily temperature fluctuations are common and 16-24 "nightly" snows happen on a regular yearly basis during the winter...plus we get 70-90 MPH wind bursts more often than not during summer storms. The house is "tested" on a monthly basis...thus I'd rather play it on the safe side.

The house happens to be an A-frame (roof at 45 deg) with a 24 foot high first floor ceiling, and I do believe you are correct on the off-center loading. On the left side of the house in which the I-beam has twisted downward, there exists an additional bathroom/closet that extends beyond the A-frame's symmetric structure...thus more load exists quite possibly on the left side due to this additional 20'x10' space that protrudes from the left side of the house and not the right. Just a theory though...as I would have thought the basement foundation walls and load bearing wood wall under this additional space would have kept it from "torqing" the I-beam.

What is kind of funny is I'm concerned about this huge steel I-beam in the basement, yet have no concerns about the wood laminate beam holding the A-frame ceiling from collapsing...it is a huge chunk of solid wood, 22"x10"x41' long. Wood > Steel it seems for this house...LOL

Thanks for the input, and anyone else please feel free to comment. Do know that I am going to hire a structural engineer to look at the situation, yet I'd love to hear the opinions of this forum too.

 

[structuresguy]

Well, one comment I would have is that I would not be 100% happy with the wood shims supporting the steel beam in the concrete notch. It appears from your photo that the steel beam sits on these shims, which in turn sits on the concrete. Over time, the wood could rot and soften, and the support for the steel could be comprimised. I would look into getting some steel shim plates installed.

One thought I have is the twist could be due to an unlevel support condition at the concrete notch. I would check that out, and if that is the case, possibly fix it with steel shims. I say possibly because it may be better to let sleeping dogs lie.... Check with the engineer you hire. Fixing the twist may cause some movement in the structure above, which may lead to cracking of drywall or other problems, particularly at window and door frames.

Also, I am personally not keen on the way the beam is supported. You have concrete ledge, steel posts, wood posts, and a wood beam/masonry wall. That's a lot of different materials, all with different stiffnesses.

PLus, I am never keen supporting steel using wood posts down to a basement concrete slab. Too much chance of moisture from the slab causing the wood posts to rot at the bottom over time, and weakening the support for the beam. You might want to have that looked at also, particularly check if a moisture barrier was provided between the wood and the concrete slab.