Steel lintel beam exceeding Lu
Steel lintel beam exceeding Lu
(OP)
I have a 14" reinforced masonry wall with a 42'-0" opening. I am investigating spanning the opening with a wide-flanged steel lintel beam W36x135 with a bottom plate. If I consider the opening length of 42' to be the unbraced length of the compression flange, the moment capacity is not adequate by the ASD Method, Section F1.3. I realize that the concrete masonry being carried supplies a measure of bracing to the beam, but how much? I haven't found any sources that give me a length reduction factor or a procedure for calculating the reduced Fb other than Section F1.3. I can go a little deeper on beam size, but not much.






RE: Steel lintel beam exceeding Lu
Don't forget to limit the deflection per code. Also, don't forget to include lateral load if in a seismic zone or wind load for an exterior wall.
I hope these ideas may help!
RE: Steel lintel beam exceeding Lu
RE: Steel lintel beam exceeding Lu
I've not used it myself but I've seen details in which a steel lintel is cast into a concrete beam so that it all fits inside the wall. It might be an idea. You may be able to then use some of the concrete cast above the steel as composite to help you out. I don't know how well this turns out in the field.
Then again, with a 14-inch wall, you could probably get a big concrete honker beam to work.
RE: Steel lintel beam exceeding Lu
I agree with the above. Don't count on the masonry for lateral support. Use additional cap plates...or a cap channel.....or external braces, etc. There is also consideration for lateral wind, seismic, or the minimum 5 psf interior partition loads that may apply. (at least one of them will apply).
RE: Steel lintel beam exceeding Lu
If this is an exterior lintel you'll be fighting weak axis bending in the beam as well.
RE: Steel lintel beam exceeding Lu
Dik