ASTM A285 is a very well known low carbon steel, so there shouldn't be any difficulties in welding it. I assume that the applicable code in this case would be AWS D1.1 (structural steel welding). I also guess that the welding will be a fillet one.
Preheat until it's warm to the hand. The welded surfaces must be prefectly clean.
If you're talking of SMAW (covered electrodes), I'd suggest E7010 for the first pass and E7015 or 7016 for the subsequents.
After each pass, remove thoroughly the slag by means of a grinding disk.
7/8 inches thickness require post weld heat treatment.
Giovanni S. Crisi
Sao Paulo - Brazil