Steel beam flange notch reinforcement

[dilbert318]

I need to cut a 3 1/4" x 24" long notch out of the bottom flange of an existing W24 beam to install a piece of equipment. I cannot find any reference material describing how to handle the reinforcement. Does anyone know of sources or methods? Thank you.

 

[rb1957]

do you know you have to reinforce it ? or are you "just" being cautious ? it looks to me as though you've lost about 1/4 of one flange ... weld a plate on the remaining portion of the flange; plate should be longer than the notch, maybe 6" at both ends, plate area should be at least the area removed.

 

[dilbert318]

It will have to be reinforced. Unfortunately the notch will be located at the point of highest bending moment. What worries me is the stress risers at the corners of the notch. Even with a radius the stress will be high. Is this something I should be worried about or am I being overly conservative?

 

[rb1957]

even though it's at the maximum moment, the reduced section still might be acceptable, no ? if you've done the sums and the reduced section is down, then you need to reinforce it. you've got something like 9" of flange remaining (and a 3" cut-out) ... i'd suggest a strap about 9" wide and 1/2 as thick as the original flange (so you're adding a bit more material).

corners of the notch should have a nice radius, something like 1" even if it makes the notch longer ('cause they've been cut sharp).

reinforcing with a welded plate that's longer than the notch does relieve the stress concentration at the notch

 

[dilbert318]

Thanks.