Header Beam reconfigued

[garys05]

Unique situation and could use help: I have a header beam with a span of 11'-3" and has load of 500 lbs/lf. The header beam is made up of 3 2x10's glued together. Here's the kicker, the header beam is not continuous, there is a built-in bar that was used to support the header beam, and between the 'left side' and 'right side' of the header there is a gap of 16" or so. I would like to fill the gap between the left portion and the right portion (with 2 x 10's glued and shimmed tight on each end. Obviously this is fine in compression, but not for the tensile stress in the bottom portion of the beam. To handle these forces, I'd like to add a steel bottom flange, which would be lag-bolted to the existing triple 2x10's. Looking for help in sizing the bottom flange, as well as qualtity, size, and spacing of the lag bolts. Picture below explains this a bit better. Thanks for any help!

 

[XR250]

That is more load than three "whole" 2x10's can take unless is it is maybe #1 SS lumber. (7.9 ft-k moment).
Trying to reinforce on the bottom will likely be tough due to the amount of shear involved. Also, counting on your infill to act in compression is wishful thinking unless it is cut perfectly.
I would replace it.

 

[gte447f]

I agree with XR250. The beam is undersized for the span, even if it was solid. Replace the beam with the right size. It's not worth doing the sort of engineering gymnastics you are proposing for such basic construction. Not to mention the level of execution in residential construction is usually consistently poor, so don't give them anything outside the box.

 

[KootK]

I agree completely with the sentiments expressed by me thread predecessors. Reinforcement's probably not the answer here. That said:

Looking for help in sizing the bottom flange, as well as qualtity, size, and spacing of the lag bolts.

You can do this with fairly simple VQ/It beam bending principles. The very real influence of fastener slip is always something to consider.

Obviously this is fine in compression

Keep an eye on stability at any potential compression infill. This setup might introduce lateral hinges into your compression load path.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BridgeSmith]

Save yourself the time and effort for design, and the labor expense to hobble together something that won't be adequate when you're done. Just get an LVL or steel beam with adequate capacity.