Elevated Platform - Seismic Attachment to Bridge Structure that allows thermal expansion/contraction

[jgwdea]

I am interested in your thoughts regarding a connection between a 20'x60' gravity-only supported elevated platform consisting of tube steel columns, WF beams, and composite deck to a 150' span of a new bridge. The elevated platform connections are all pinned, so it does not resist lateral loads. The plan is to connect one of the 60' sides of the elevated platform to the bridge structure with a connection that has both horizontal and vertical slotted holes (horizontal slots on the steel element tied to the platform and vertical slots on the steel element tied to the bridge). This will allow for differential vertical deflections under live load and allow the bridge to thermally expand and contract longitudinally without tearing up the platform structure connections.

In a design seismic event, the idea is that as the bridge shakes, the platform connections will engage and the platform will go along for the ride.

ASCE 7-05 sections 12.1.3 and 12.1.4 require a positive connection between all interconnecting parts of the structure.

1) Does the code allow a slotted connection in the direction of seismic loading?

2) Do you think that the slotted holes will result in larger dynamic forces during a design seismic event?

Thanks for your input.

I appreciate it.