Steel truss member replacement 3

[bridgeengineer2007]

I am looking to see if anyone has experience with replacing individual steel truss members (eyebars, pins, chords) due to extensive corrosion. The two-span steel truss bridge will be closed to traffic so I am looking to find a way to relieve the load off of the member being replaced. Temporary support from the waterway below is not an option and I do not want to remove the truss in it's entirety in order to replace members on the ground. Ideally I want to be able to have the contractor assemble a frame support system on the bridge deck that can be moved, which would relieve the load from individual members making replacement easy.

Any thoughts or details from successful past projects would be appreciated.

 

[bridgebuster]

This is a link to a set of plans by NYSDOT involving truss member replacements.

Link



Our office did a repair of a laced box beam (bottom chord) a few years ago. We left the gusset plates and pretty much replaced everything else. I'll look around for the plans. There was a temporary member installed. Fortunately in our case, the member stress was low and in compression (bascule bridge).

This report from TexasDOT FHWA/TX-0-1741-1 (April 2001) has some useful information. Repair and Strengthening of Old Steel Truss Bridges by ASCE (1979)is helpful but doesn't really get into member replacement.

 

[bridgeengineer2007]

Thank you! This is great information.

 

[bridgebuster]

you're welcome

 

[Lomarandil]

Typically we'll end up using hydraulic jacks to temporarily transfer load out of the member to be replaced and into a temporary member (or rod). Details vary depending on the bridge construction, but we've come up with a lot of different configurations depending on the project needs.

Eyebars are nice in that it's easy to find the point of zero stress before a cut (since they buckle under such small compressive forces).

 

[bridgeengineer2007]

Thank you Lomarandil!

Do you have any details of the hydraulic jack configuration that you can share?

 

[Lomarandil]

Sorry, that's our main line of business, so details are proprietary. I'll share a photo from the SFOBB project