Glass is very brittle and concrete (or tile) is very hard, not a good combination.
I know a fellow homebrewer had a carboy basically explode in his hands while carrying it, he said he didin't hit it on anything it just spontaneously blew apart full of beer. He used one of those webbing strap carboy haulers to carry it from his fermentation chamber across the room where he had a somewhat high shelf he would place the carboy on in preperation to rack the beer off the yeast cake. Set it down and got his hand under it and as he lifted it it came apart.
He had terrible cuts, had to have surgery on one of his hands, many stitches on both. He was out of work for several weeks at least, it was a long time ago. He, and I, believe there were microscopic stress cracks in the carboy because he said he always closely inspected them after cleaning to be sure they were spotless and believes he'd have seen a crack.
I stopped using my carboys after that, switched to better bottles and then to fermenting in sanke kegs. My carboys collected dust until I got into winemaking and I went and bought real milk crates, not the lightweight things one may see at walmart or similar stores.
I use super crates now from farmplast, a company in NJ that manufactures them. They are rated for 250 Lbs but I am so scared of breaking carboys that I am considering making some kind of reinforcing bottoms out of thin plywood for them.
I know this is nearly the worst case scenario and it is another expense but once bitten twice shy and I wasn't even the one bitten but saw what it did to my friend.
I know I'm just a stranger to whoever reads this but please trust me when I say you DO NOT want to experience (or even see) the wounds I saw!