Hello and Happy new year

I am in the middle of repairing my rattling exhaust shield which I had to remove from the car to repair.
To get it out I had to remove the chassis brace (Smaller one) which goes accross the exhaust tunnel (near the cat) under the car, however when loosning the nuts to remove it, 2 of the studs sheared off and typically both on the same side which means I am unable to reattach the brace.

Does anyone know if these can be replaced and is it easy to do?
Are they accessed from inside the car under the carpet, are they bolts which can be undone or are they welded to the floorpan?