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Elastomeric Bearing Forces for Single Span Zone 1 SDC?

Elastomeric Bearing Forces for Single Span Zone 1 SDC?

Elastomeric Bearing Forces for Single Span Zone 1 SDC?

I am designing a single span bridge and the seismic zone is 1. This is a service bridge so it is only 16' wide (two girder). As per AASHTO (8th edition) sec, my As value is >0.05. If I use 0.25 times vertical reaction (dead + live) it is 54kips. I am really confused as to what to do with that number for an expansion, elastomeric bearing. Does this mean my expansion bearing needs anchor rods or a shear key to take the transverse load? Any help is really appreciated. Sorry if this is an easy question. This is my first bridge design.

RE: Elastomeric Bearing Forces for Single Span Zone 1 SDC?

Yes, you need anchor bolts or some other restraint system sufficient for the Extreme Event loading, unless the elastomeric bearing is fully restrained top and bottom (I believe only having the bearing vulcanized to top and bottom would qualify as being fully restrained).

I believe the commentary still suggests a value gamma LL of 0.5 (so a value of 1/2 the design live load, is typically considered appropriate).

If I may ask, was a integral abutment considered?

Rod Smith, P.E., The artist formerly known as HotRod10

RE: Elastomeric Bearing Forces for Single Span Zone 1 SDC?

Yes, shear key/creep blocks would be a simple and not very detail intensive option for addressing the minimum code prescribed lateral load. A creep block right between the two girder lines would be ideal. Just make sure your diaphragm above the creep block can drag the inertial load from one girder to the other side to engage the creep block.

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