High Rockers Bridge Bearings 2

[OLDSOUL22]

Hey, I'm working on a bridge maintenance projects and we are changing the bridge bearings. 8 bearings each abutment ( total 16). the bearings we had is high rockers bearings. the project timeline is very tight and the through traffic cannot be closed. ( one lane should be open all times). I tried taking all the dimensions for the rockers to get the fabrication started before jacking the bridge and getting the old rockers out. but there is no way to figure out what is the inner configuration of the rockers is. Anyone who have any old standard drawings that shows the fab details for these type of bearings? Any reference or pointer would be much appreciated!

 

[Ingenuity]

Check out this thread from earlier this year: thread507-478914

Notably, contributions/references by bridgebuster, and specifically the reference BRIDGE REHABILITATION AND REPLACMENT by SUNG H. PARK, dated 1984.

 

[jorton]

I'd replace it with a modern bearing, preferably an elastomeric bearing if your movements allow. You can use a steel pedestal consisting of a W or HP shape with top and bottom plates to make up the height difference. On some project we've treated the pedestal as temporary and then built a concrete pedestal around it. On others we have galvanized the steel pedestal and left it alone. The trickiest part can be figuring out how and where to install new anchor bolts - it looks like you face that problem even if you replace the bearing in-kind. NSBA has some guidance available on bearings for steel bridges. They'll soon be coming out with additional guidance on common steel bridge maintenance issues including bearing replacement.

 

[SlideRuleEra]

Agree with jorton, elastomeric bearings. Keep it simple, the less the Contractor has to do to those riveted girders in that deteriorated condition the better.

http://www.SlideRuleEra.net

 

[hokie66]

That bridge looks like it has much bigger problems than its bearings. But perhaps you know that.

 

[bridgebuster]

I agree with the others; my preference too would be an elastomeric bearing on a bolster. attached are some details of elastomeric bearings with bolsters. However, I don't see a problem with replacing a high fixed bearing with a similar. However, I wouldn't replace a high rocker with similar, particularly if seismic is an issue.

 

[OLDSOUL22]

Thank you all for your help!
I ended up doing elastomeric bearings with w-bolsters as the majority suggested. Definitely cheaper to fab with all the machining for the old rockers. I'll post some pictures when I go the site.

Sr. Project Engineer
MSc in Civil Engineering

 

[bridgebuster]

MAMRO - just curious, is this the same bridge with the deck problems?

 

[OLDSOUL22]

bridgebuster,
This is a different one, single span bridge. Same owner though.

Unfortunately, that's the only picture I have now showing a side view of the expansion bearings. pedestal is a w section and top is elastomeric bearing with PTFE sliding surface.

Sr. Project Engineer
MSc in Civil Engineering

 

[bridgebuster]

Thanks MAMRO.

 

[jittles]

Details of the bearing aside, thanks for the update!