There should be a metallic bonding grid embedded in the cement/concrete. There is almost always a bonding wire coming off of the metallic grid embedded in the concrete and heading off towards the equipment pad. Often a little searching around the equipment pad will turn it up.
For ladders, you normally either drill the hole for the anchor cups and locate some metal to bond to in the hole you just drilled, or you cut a slot in the deck and insert a bonding wire running from the anchor cups to the closest location where you can locate a connection to the bonding system. If you are doing extensive renovations it is usually very easy to turn up such a spot, but if all you are doing is adding a ladder it can get tricky to find somewhere appropriate.