Previous building owner faced a similar situation about 15 yrs ago when they added an addition at the opposite end. At the time the previous owner chose to modify the bottom chord of the bar joists by welding a 1/2" x 6" plate to bottom chord. There was no engineering review just a seat of the pants design by one of the key employees. This has worked well thru several major storms over the years.
New owner wishes to use W14 x ? as infill beams between the existing bar joists. Keeping the infill beams shallow allows him to not interrupt utilities that are running thru the existing bar joists. I've designed a grid of 5 pcs W14x43 x 50' long beams with bridging on 12.5' ctrs. to support the top flange of the W14.
The dead load induces about 1/2" sag at the middle and 2.5" at full snow load.
- I'm curious about how to reconcile the sag from dead weight?
- How close should the stiffness of the new beam grid match the existing bar joists to insure best loading practice
Thx in advance