Thread by @MattDursh

The Kerch Bridge in Crimea has been hit with underwater explosives.

The bridge is still standing but there is no doubt damage to the foundations.

This 🧵 covers what the bridge damage could be and how challenging the repairs will be. 1/

The bridge uses a 745 feet truss arch main span to support rail and vehicles on separate structures.

The blast appears to hit the rail bridge, which is a more vital span for military transport.

The main span foundations use plumb and battered (angled) steel pipe piles. 2/

There certainly piles that have failed on the bridge from this blast. How many and locations we may never know.

There are enough piles remaining to support the self weight of the structure (it is still standing).

What about its ability to carry live load or resist storms? 3/

Bridges are conservatively designed to resist worst case force effects, loads the bridge likely will never see. These are called Strength Loads.

Routine everyday Service Loads require less demands of the structure. Because of this I anticipate the bridge to be reopened. 4/

But the structures ability to resist robust Strength Loads for worst case live load and 100 or 500 year storm events is compromised.

What do the repairs look like? Not easy to say the least. 5/

You cannot install new piles under the existing substructure. They will need to be installed outside the footprint. However, this changes the demands on the existing footing. Significant retrofits and repairs are needed.

I will update as more info becomes available. 6/6