Howdy all,

Walking today I again spied this pair of huge rocker supports under this bridge. They sit on a plate, on piers, and the river bridge rests on these two supports, with the weight from above concentrated on two pins (rollers) between the bridge and the rocker.

Do these big rocking supports have names? What about the pins between the bridge and the rockers?

Thanks!

Rocker bearing. I believe the pin is simply referred to as a pin.

quote:

Originally posted by a1abdj:
Rocker bearing. I believe the pin is simply referred to as a pin.

Yes, the entire assembly is considered a rocker bearing.

The components are from superstructure (beam) to substructure (pier) are as follows:

Sole plate

Pin

Rocker

Masonry plate

Most likely there is a pintle that protrudes from the masonry plate in to a keyway in the bottom of the rocker..

I am an NBIS certified bridge inspector and I can’t answer your question any better than the previous posters.

The pin allows the beam to rotate to accommodate vertical deflections of the spans and the rocker allows the bridge to translate longitudinally due to thermal movements.

Thank you all! I saw the pin and wondered if the pin steel was different than the beam steel. And if it was greased.

Listening to David McCullough's Brooklyn Bridge novel, I get the feeling those rocker bearings are rated for 50x the weight upon them. And from an engineering point of view, that "little bridge" does not weigh all that much. Spring Garden Avenue Bridge over the Schuylkill.

quote:

Originally posted by RespectTheAmish: The components are from superstructure (beam) to substructure (pier) are as follows:

Interesting. The layperson looks as that as the masonry plate first but it is the other way around in engineering.

Heck of a big nut cracker.

I think it is interesting that there appears to be considerable shift to the left.

Would be neat to come back in winter to see if that deflection changes by a visible amount.

Based solely on the rust streaking., I'd say the shift is pretty minimal throughout the seasons. Is there anything keeping the rocker in place at the rocker end or simply the vertical weight/friction at that point?

Why would I be amazed?

Once again, no matter what the subject or question of an obscure rare thing, within a few minutes at least one expert will answer.

SigForum, greatest place on the planet.

quote:

Originally posted by Patriot:
I think it is interesting that there appears to be considerable shift to the left.

Would be neat to come back in winter to see if that deflection changes by a visible amount.

The bridge is shrinking.

I'll get dimensions of the masonry plate and we'll calculate its weight. But I'm guessing 4,000 pounds of American steel.

quote:

Is there anything keeping the rocker in place at the rocker end

quote:

Most likely there is a pintle that protrudes from the masonry plate in to a keyway in the bottom of the rocker..

quote:

Originally posted by RespectTheAmish:

quote:

Originally posted by a1abdj:
Rocker bearing. I believe the pin is simply referred to as a pin.

Yes, the entire assembly is considered a rocker bearing.

The components are from superstructure (beam) to substructure (pier) are as follows:

Sole plate

Pin

Rocker

Masonry plate

Most likely there is a pintle that protrudes from the masonry plate in to a keyway in the bottom of the rocker..

I was going with rocker thingy, on the flat whatcymacallit, attached to the pivottishpoint.

quote:

Originally posted by DoveEgg: The pin allows the beam to rotate to accommodate vertical deflections of the spans and the rocker allows the bridge to translate longitudinally due to thermal movements.

With Thanksgiving coming up, I'm thinking a cloth couch will assist in accommodating vertical deflection due to excessive deviled egg consumption as well as provide warmth and comfort as I translate longitudinally from general gluttony.

Can you smash pennies flat under that rocker?

quote:

Originally posted by Hamden106:
Can you smash pennies flat under that rocker?

Thank you for saying what I was thinking.