US 17 Bridge Repair, South Carolina

[PColumbus73]

I attended a public information meeting for proposed repairs to the US 17 bridge over the Waccamaw River in Georgetown, SC.

SCDOT is proposing replacing the piers on the existing bridge, but keeping the rest of the structure intact. The new piers would only be for the spans over the main channel of the river. During the meeting they mentioned that scouring was the reason they were proposing this repair.

I am not a bridge engineer, but what stands out to me is how the cross-beams for the new piers across the central span would be offset from the union of the existing girders. If there are any bridge engineers out there, I'd love to hear your opinions.

To me, it appears that if the new support beam is not directly under the bolts of the existing girders, the weight of the central span would have to travel through the bolts onto the new beam. Would that create tension, or a shearing force, straining the bolts as the weight is transferred off the main span?

Also, it appears that the stair-step nature that the load from the central span, through the bolts onto the adjacent span, down to the beam, over to the towers, and down into the ground, seem less than ideal. Although I am aware that wide bridge spans are used in instances where an off-ramp curves over another.

These graphics were all they had, and I don't have access to the construction drawings, but I would be interested in hearing what actual bridge engineers have to say. The design for these new piers is something I've never seen before.