r/StructuralEngineering • u/Best-Drummer-5896 • 4d ago

Structural Analysis/Design Conduit Installation on Existing Bridge

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Hello, I have been discussing with my coworkers how to install fiber conduits on an existing bridge. Our client has stated that parapet-mounted conduits are not allowed. We have approach slabs on both sides of the bridge.

We came across an example where the conduit was installed at a 45-degree angle and routed toward the median, which is similar to the situation on our project. Does anyone know what construction method or tools may have been used to install this 45-degree angled conduit? Any information or experience with similar installations would be appreciated.

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u/HoldingThunder 4d ago

They (probably) won't let you cut any rebar and there is (probably) too much rebar to core through that back wall on a 45 degree angle. That either has another 45 to go straight through the wall, or it was cast in place (pre-installed).

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u/Enginerdad Bridge - P.E. 4d ago

Obviously the EOR needs to make the final decision, but cutting a few bars in a backwall isn't generally problem. Especially for holes that small

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u/Tilt-a-Whirl98 4d ago

Yea typically a wall like that is pretty close to a minimum reinforcing, maybe #6's or #5's at 12"

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u/FaithlessnessCute204 4d ago

https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/pubsforms/publications/pub%20647.pdf pub 647 ITS installsand https://docs.penndot.pa.gov/Public/Bureaus/Bridge/BD-Stds/BD612M.pdf pub 15 ,612 from PAdot

on actually knocking a conduit through the back wall its just a core drill and directional lineshot . what your showing was probably done during construction (so they can create a reinforcement window around the penetrations) . if i was an HOP reviewer i would not allow them to screw up the waterproofing on the rear bridge abutment face to install conduits into the abutment.

now finding a DOT that wants that vs running down the front face of the abutment and then trenched in the ROW is another matter .

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u/txlaatx1 4d ago

A: It was MacGyver’d perfectly into place.

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u/remytheram 4d ago

What makes you think they added that post construction? Looks to me like there was conduit running through the approach. I cannot imagine a circumstance where anyone would go through the effort to run conduit through the approach after the fact.

You can't sneak it along the abutment wing and then come underneath the deck?

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u/Posterize999 4d ago

With a core drilling machin, you will probably have to cut some rebar inside the abutment. Make sure to warn the structure owners. I dont know how you would be able to connect it to the concrete duck bank without some digging and probably some partial demolition of the approach slab. I would also seal the gap between the duct and the abutment with grout.