A crack in your concrete does not prevent you from anchoring into it. In fact the anchors these days are designed/tested for use in cracked concrete. While the concrete substrate does lose some strength, I think you'll find that the load values are more than acceptable. The only situation I would avoid entirely is if the spot you will be anchoring to is cracked to the point where it is starting to crumble. My recommendation is to use the DEWALT Screw-Bolt+ Anchor. You do not have to worry about edge distance with this anchor is it is not a wedge type anchor and it is approved for cracked concrete by the latest ICC building codes.
Your garage slab is a minimum of 4" thick by code, reinforced by rebar or at minimum reinforced by wire mesh, and is 2,500 psi at minimum. Given those conditions if you use a 3/4" diameter x 2-1/2" long Screw-Bolt+ you'll have 1,150 lbs load capacity in tension from a single bolt, meaning pulling out directly up from direction it was installed. This is the force we are most concerned about here, the shear load is much higher but also not as relevant. There are 4 anchor points per post probably, so at minimum using the 3/4" diameter x 2-1/2" long Screw-Bolt+ you will have a load capacity of over 6,000 lbs at one post. I personally would use the 3/4" diameter x 4-1/4" long Screw-Bolt+ if you can.
You might wonder how I know this and why this is valid. I have worked in the construction industry for almost 15 years selling these products, more specifically now for DEWALT.
http://anchors.dewalt.com/anchors/p...rs/screw-boltplus/screw-boltplus_hex_head.php
http://anchors.dewalt.com/anchors/_documents/uploads/dw_screwbolt_e_techpage.pdf?1610289085
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