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I think in that situation the fixings are usually going into a solid concrete floor and (at least by design) are not constantly stressed in one direction in the way that shelf will be due to its weight (and the weight of stuff on it). If it's being fitted into brick then I really don't rate its chances. If you were to use long masonry screws (preferably fitted into at least 2 separate bricks) then maybe, but I wouldn't fancy it with expanding bolts or plugs.
With that much stick out? It's a lot further than a handrail.