I am would like to uderstand why the engineer is having me remove back up bars on bottom flange of weld.The welds that i am talking about are full pen. moment welds attaching w?*??into face of col.the average beam size W18*40, col.s are W12*136.full pen top and bottom flange
Sounds like a seismic moment connection. FEMA 350 has typical details of these type connections. this is not uncommon to remove the backing bar and add an additional fillet weld. John Wright
I agree, The backing bars may create false indications which may be constued as LOF, etc.. FEMA and newer procedures require the removal of the backing ; and some engineers require and additional reinforceing fillet weld at the point of stress. It seems the botton flange of the beam receives the most stress during a sesmic event.
The unfused portion of the backing bar where it meets the fused portion makes for a notch that can start a crack at the weld root during a seismic event or in a fatigue application.
Sounds like a seismic moment connection. FEMA 350 has typical details of these type connections. this is not uncommon to remove the backing bar and add an additional fillet weld.
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