Falling Shelves

We noticed this sad state of affairs fairly early on in the firing,but too late to do much about it: I did manage to sneak in a small prop to support one of the shelves,but it didn't make much difference. All our cones were gone,also the rings,so we had to fire and salt by the seat of our pants,which turned out to be pretty reliable; when I opened the kiln yesterday afternoon cone 10 looked to be down,everything got well salted,and the mayhem was not as widespread as expected - quite a few stuck pots were salvageable,some had even held their ground and were unaffected by the fall,and the back [& larger] half of the kiln was fine.
I'd assumed that my foolhardy shelf placement had caused this collapse,but discovered that one of the props on the [permanent] bottom shelf had given way. Inevitably, the most interesting pots were a couple that fell off their shelf right into the fire-mouth,irrevocably welded together [and to the kiln] but with really nice colour and salt effects.