Existing hammerhead pier supporting new superstructure 1

[rwb3rd]

I have a bridge project where the existing superstructure is being replaced with a wider superstructure. The bridge is on a curved alignment. The existing beams (dog-legged beams) are also being replaced with curved beams. The question is should the existing hammerhead piers satisfy the current AASHTO code requirements (the project is being designed under LFD) or the code requirements when the pier was designed back in the early 60's? The problem is concerning the shear strength of the cantilever arms due to inadequate shear reinforcing. The allowable shear stress was higher in the AASHTO code back in the 60's than it is now. The shear stress would meet the older code but not the current code allowable shear stress.

 

[bridgebuster]

It's a policy decision by the owner. How inadequate is the reinforcement for the new superstructure loads? I think that's what will drive the decision.

In NY, the substructure reinforcement in the older bridges doesn't meet seismic requirements, but when we do a rehab we don't retrofit the substructures. It would cost too much. Similarly, no one goes about upgrading bridges with each new addition of AASHTO, (which seems like they're getting a bit out of hand with the constant revisions.)