What did you think of my post #59 as a means of protecting against bearing failure?
> What did you think of my post #59 as a means of protecting against bearing failure?
What I think is that it is more things to go bad. If frozen bearing were a primary cause of bridge failures, I haven’t heard of it. Every bridge I have ever inspected has bearings that are either well on their way to jamming up OR, are already there. This is not only old bridges. Some less than 10 years old are in poor shape.
I notice that some of the newest interstate bridges have a completely different manner of containing expansion and contraction. Basically, the use long wideflange beams pounded into the ground with the weak direction in the direction the bridge is supposed to move. The beams are surrounded by a corrugated metal tube. The top of the bridge rests on the beams. I believe the idea (although I have NOT talked to any designers about it) is that the beam is supposed to be able to move within the metal tubes. We will know in 30 or 40 years if this is any better.
With a big enough motor, low enough gearing, and proper maintenence, it should work, but those are not givens.
Six roller nests and at least 4 rocker bearings make at least ten such assemblies for this one bridge.
Bottom line always comes down to the client and how much they want to spend. The technology exists to build some very long lasting and competent structures, but often the design issues are resolved by a less than knowlegable client’s preferences and whims.