notched flange in I Joist

[bigmig]

We have a detail on a house where we are trying to bear some
I-Joists on the bottom flange of a steel beam. In order for the joists to extend far enough to reach this point, we have to cut off the top flange for about 3 inches.

My boss says all the shear is in the lower flange, but every thing I have found says don't cut flanges on I joists with certain exceptions, and I certainly don't find any references to completely removing the top flange.

The contractor questioned it, and I know the building inspector will see it.

Has anyone ever done this?

 

[jtx]

Get a hold of the joist manufacturer about this. They should be able to assist you.

BTW I have always seen joists run over the steel beam (I am assuming this is for a floor). What are you trying to accomplish by seating the joist on the bottom flange?

 

[msquared48]

I agree with getting ahold of the joist manufacturer and, in general, it is not a good idea to cut the top flange. You do not want to void your warranty.

However, if Iunderstand the situation correctly, this is similar to coping the top flange of a steel beam to connect to a steel beam. I strongly suspect that if this is only the last 3" or so of the joist, and if the web mateial is not cut, where the shear is that transfers to the bottom chord, then the joist will be OK. But check it out anyway.

Mike McCann
MMC Engineering

 

[msquared48]

In thinking about this a little more, one possible problem that could occur would be the possible lateral instability of the plywood web in the cut area, however, this could be alleviated with some blocking.

Mike McCann
MMC Engineering

 

[jtx]

It may also be a good idea to adhere plywood to either side of the web to reinforce it for bearing. That may take care of your concerns about shear as well.

Again...get direction from the mfr.

 

[bigmig]

I thought about the instability of the remaining web and added some blocking. The attached sketch should firm up the scenario.

 

[port125]

There are face mounted hangers available that hang the I joist outside the face of the flanges. It sounds like using some of these hangers would eliminate the need to cut the I joist by putting the connection outside the beam. They make a good connection and would most likely not be questioned. They could be used if notching voids your warranty.

 

[spats]

You show the I-joist bolted to the bottom flange. You don't have enough width on the flange to do this, do you?

 

[bigmig]

SPATS, I have since gone to a Powder actuated fastener, set further
to the left (farther from joist end) to help with this.

 

[ToadJones]

in this situation, I like to "fill" the web of the W-shape with 2x10 (or whatever) blocking and through bolt (carriage) bolt it through the web of the W. Then, you can use a regular joist hanger.

 

[ToadJones]

bigmig-
you'll likely shatter and split the end of the I-joint if you shoot it with a powder gun.

 

[jtx]

Let alone this happening!!!

http://www.osha.gov/OshDoc/data_FatalFacts/f-facts48.html

 

[bigmig]

The problem with using hangers is that you side load your W flange, introducing a roll that you have to counter. By bearing on the flange, we can minimize this.

Regarding powder actuated fasteners, per my research if you select the proper length fastener you won't shatter your wood. The fastener is selected based on steel grade and thickness. It would shoot through the wood like it wasn't even there at which point it hits the steel and "embeds". If your faster embeds correctly, it just clamps your wood down.

And you don't aim it at people. Note well taken.