The Northridge Earthquake (Jan 17, 1994) destroyed 3 concrete freeway bridges. About a month later, I saw a letter to the editor of the Daily News saying that we should build freeway bridges out of steel. The letter pointed out that none of the rail bridges, which were made out of steel, were damaged. Is this a good idea?
IIRC, concrete with steel re-enforcement is extremely good at resisting earthquakes. The bridges that collapsed didn’t have the steel re-enforcement and were scheduled to have it added.
It depends on how the steel reinforcement is done!
The Highway 880 “Cypress Structure” in Oakland CA was reinforced, and flopped like a flounder on a boat deck. The vertical reinforcing rods weren’t bound together horizontally. The thought was (apparently) that since the rods were encased in corcrete, they were bound enough.
I don’t know about railroad bridges, but the welded joints in numerous buildings cracked in that and other quakes. There was a lot of head scratching about this because those that cracked used rod materials that were recommended by the welding industry.
It seems to me that the issue of steel v reinforced concrete is one that won’t be decided soon, if ever. There might not be a clear structural choice, so esthetics, economics, politics etc. enter into it. Any structural engineers handy?