Single Span Bridge Zone 1

[RyUIUC]

I am evaluating loads submitted by another firm for a single span bridge in seismic zone 1 (or seismic zone A). I am a little confused by the minimum connection design forces in the specification. AASHTO LRFD Section 3.10.9.1 states that all single span bridges regardless of zone must be designed for a connection force of As (=Fpga*PGA) x tributary permanent load. The next section (3.10.9.2) then states for bridges in zone 1 that the minimum connection force equal 0.25 x the tributary permanent load (for As>0.05).

My question is which section supersedes the other? In my case the zone one requirements are substantially greater so I assumed they governed but the calulation I am reviewing is using the other criteria for single span bridges.

 

[Qshake]

For the single span bridge, you should use 36.10.9.1.

Regards,
Qshake

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