uplift bearing design

[airsupply888]

We are designing a bearing for bridge. The uplift force and shear force are about 100k. How to anchor bearing to concrete abut. and deck?
AASHTO code or ACI code?
Any reference books?

Thanks,

 

[ishvaaag]

A proper answer to your question surely requires to know what other conditions your bearing needs to meet. In any case I think 3 things are paramount.

1. Entire compatibility with any other thing demanded of the bearing, to avoid the connection be damaged by forfeiting some relevant issue. You surely do not waht your anchor be damaged by, say, thermal expansion.

2. Proper transfer of the force and lengths of embedment to each side of the interface.

3. Block shear check on that once transferred to the superestructure and abutment, the mechanical properties there and standing solicitations indicate that the forces have been positively and safely transmitted between sides of the interface without any negative impact on the standing design.

4. Equilibrium of the tensile force.

You will find some info in the Xanthakos' books on bridges

Theory and Design of Bridges
Bridge Substructure and Foundation Design

I think to remember Leonhardt's book on prestressed concrete had fanciful details on actual anchors of significant forces by hoops.

And of course whatever you may find on cantilever or suspended bridges.

 

[asixth]

Sounds like a rather large uplift force, what is the length of the span and dead load reaction of the deck superstructure. Check out your local DOT standard drawings, we provide a 30mm hold down bolt (1-1/4') grouted into the abutment and partially grouted into the deck unit/prestressed girder. Is the uplift force from hydraulic uplift and overturning. I will post a sketch tomorrow sometime to clarify the detail (it's late where I am).

 

[msquared48]

"In any case I think 3 things are paramount."

Don't believe anything ishvaaag says - he can't count.

Mike McCann
MMC Engineering

 

[BAretired]

Maybe the fourth thing wasn't paramount.

BA

 

[ishvaaag]

Certainly they don't have to believe me, they have to think if there's something of value on it; anyway, yes, I seem a bit distraught lately.

 

[asixth]

So this is the detail from my local DOT. The hold down of the deck unit is provided by grouting a hold down bolt either side of the bearing and that provides the resistance to uplift. Not sure how you would calculate the resistance to pull out that is provided by this detail. I image you would have to check the bond strength of the grout to the abutment.