If you looked only at yielding of the bolt, you'd have a capacity in the range of 15 kips. That's not the only consideration, though. You need to know the length of embedment and there have been studies on J-bolts that show that they can pull out without spalling the concrete.
If you look at the concrete embedment, you'll have to compute a failure cone (45 to 60 degrees)and figure the resolved shear-tension failure of the concrete at the cone face.
Depending on the edge distance, the influence of the cone area, spacing of the bolts, strength of the concrete and maybe a few things I'm not thinking of at the moment, you'll be at one of the conditions, most likely with the concrete parameters controlling.