Tie-down Design for Uplift at a Bridge Abutment 1

[Skyhook7]

I am designing a bridge for a private party and the span balance is not good. I have uplift at the abutments. I have not seen a detail for a tie-down before and was wondering if someone could shed some light on this. One abutment has around 15 kips and the other is around 2 kips.

 

[bridgebuster]

Design the tie-down as a member subject to tension; add what you believe is an appropriate factor of safety - keep in mind corrosion of the bolts; and check the pullout resistance of the concrete.

 

[yakpol]

Skyhook,
It seems the uplift is really small, did you consider adding weight at abutments? If superstructure is integral with abutments? If not, all you need is well-embedded into abutment anchor bolts.

 

[Dinosaur]

AASHTO states the design requirements for hold down devices resisting uplift at substructure units. It is in Chapter 3.17. There is a penalty to be paid when uplift is possible so the approach mentioned by Yakpol would be preferred by many designers.

Dinosaur

 

[miecz]

I'm dealing with the same problem at an expansion bearing. I've decided to carry the force through the end diaphragm with a linkage that allows for the expansion/contraction.