It wasn't a missile, most of the force went upwards and in total did little damage to the bridge (one lane of which is still in use).Interesting, I'm still not convinced a missile has landed on the bridge, though. I've read somebody saying that it could have been fired up into the bottom of the bridge from the river or riverbank and that bridges are built to withstand heavy down pressure and wind from the sides so the bottoms can be the weak spot. That made sense and very clever if the Ukrainians have been able to get that close.
I think the more likely option is a bomb in the lorry crossing the bridge, this would explain the majority of the thrust going upwards with the chasis/bed of the lorry protecting the bridge.