Do It Right! Lessons from the field not to be repeated
Superstructure
- Ensure that bridge seats are cleaned off and ground smooth and level prior to setting bearing assemblies.
- Try to make sure they stay clean until the beams are set.
- Make sure the holes for the fixed bearing anchor rods are drilled deep enough that only 3 inches of the anchor rod project above the bearing plate.
- Make sure the railroad signs off on the contractor’s proposed method to secure a single beam over live traffic!
- Don’t let them set the bearing pads until the bridge seats are clean, smooth, level and at the correct elevation.
- Make sure the bearing plate is clean, too!
- If you see something like this STOP! ‐ Don’t let them just ream out the holes!
- They should cut the holes in place, or match‐mark better. Reaming out this much material is not allowed!
- When you’re doing rehab work on an old steel bridge, make sure they either do a better job of match-marking or drill the plate in place—or else they will need to bring a lot of extra plate with them.
- Make sure the holes line up!
- Don't use your cross-frame diaphragms for erosion control devices!
- Make sure to use substantial cribbing if you’re going to be setting the diaphragms in the mud!
- Don’t walk on the steel either!
- Make the contractor clean up the bridge seats, check the elevations, and grind them to pass tolerances, before letting them place the bearing assemblies.
- Looks like they are setting beams
over live traffic. - How will they support the beam being set until a second beam can be tied to it?
- Will the slack chain prevent the
beam from rolling over?
- Hopefully, this will be caught in the design phase on your job, but if the bearing plate looks like it’s close to the edge of the bridge seat, call the Bridge Office!
- Make sure the contractor submits an erection sequence, and provides shoring towers when building bridges using curved girders
- Also make sure the shoring towers are adequately supported!
- It pays to do your homework before tightening the connections.
- In this case, anchor rod has to be installed before the diaphragm connections can be tightened up.
- Make sure to check the shop drawings and check to make sure the pieces fit together PRIOR to this point!
Big three crane pick
The anchor rod fits after all!
- Clipped, primed sole plate
- Moved diaphragm to other side of web stiffener
- After a few modifications, everything fit nicely.
- Measure the distance between the pintles, to make sure the distance is the same between the holes they fit — before you're ready to set the bridge!
- We need to have the contractor order new hardware.
- The galvanizing is dusting off already. This is called “Zinc Bloom”, and the bolts may break before the connection can be tightened to the required tension.
- Don't use rusty hardware!
- Lots of steel in the air at once is part juggling act and part ballet!
- Setting steel beams with more than two cranes at once requires the crane operators work in synchronicity.
- The use of shoring towers may be required on your project if the bridge has curved steel girders.
- Make sure to get a Certified Erection Plan from the contractor prior to lifting any girders in the air.
- Some assembly required!
- Someone didn’t measure this new angle very well, or perhaps they are trying to put it in upside down?
- It looks like they will have to re‐fabricate something. Don’t let them ream the holes out unless you check with the Bridge Office first!
- Make sure all the threads of the nuts are
engaged. It is preferable to have between a
full thread and 3/8” of “stick out” after
tensioning. - All bolts in a connection should have the same
Air splicing a three-crane pick
- If possible, set each line of steel beams from one end of the bridge to the other.
- Note that these ended up being out of line about half the width of the top flange.
- We should always have at least an inch between the tops of concrete beams.
- Please call the Bridge Office if your beams touch, have a large sweep, are too long or too short, or have other problems.
- How will this diaphragm ever line up?
- Make sure that the diaphragms between concrete beams meet the beam at 90 degrees.
- Check to make sure the diaphragms are
lined up correctly. Sometimes the holes for
the clips are cast in the wrong spot.
- We generally like to have at least an inch
between the tops of abutting concrete girders. - I like to have them set the fixed end of the
girder placed first, then have them set the
expansion end. - This way, if a pad has to be adjusted, the anchor rods can still be installed.
- Today’s beams are supposed to come out with the last 4 feet sealed at the casting yard.
- It is supposed to help beam end strand corrosion—check that it is there because after construction, you can’t see the end easily.
- Make sure to inspect concrete beams when they are delivered to your project and document any deficiencies.
- Just because they have the state stamp, doesn’t mean they were inspected!