AREMA Surcharge for retaining wall and culvert wingwall 1

[wsengineer]

Hi,
Is it common practice to include surcharge from E-80 on culvert's wingwall for culverts that cross underneath railway? Is there a certain distance that the surcharge does not need to be applied to wingwalls?

I've read through AREMA and did not find wording that, at a certain distance, E-80 surcharge loading can be ignored for concrete retaining wall and culvert wingwall that are parallel to to rail tracks. When I include the surcharge, it results in large footings and key depth to help resist sliding. Though, I did convert the surcharge to lateral loading which results in sliding as the critical design.

As compared to highway/roadway application, in AASHTO, live load surcharge shall be applied to all walls that retain soil where vehicular load acts wtihin a distance equal to one-half the wall height behind the back face of wall, or virtual back of wall.

thanks!

 

[SlideRuleEra]

1) ...include surcharge from E-80 on culvert's wingwall for culverts that cross underneath railway?

2) I've read through AREMA and did not find wording that, at a certain distance, E-80 surcharge loading can be ignored for concrete retaining wall and culvert wingwall that are parallel to to rail tracks.

3) When I include the surcharge, it results in large footings and key depth to help resist sliding. Though, I did convert the surcharge to lateral loading which results in sliding as the critical design.

4) As compared to highway/roadway application, in AASHTO, live load surcharge shall be applied to all walls that retain soil where vehicular load acts within a distance equal to one-half the wall height behind the back face of wall, or virtual back of wall.

1) Absolutely, if valid calcs indicate the wall is loaded by the surcharge.

2) IMHO, no "Code", including AREMA, is a "cookbook" that allows a design to be mindlessly prepared.

3) Refer to my response to Number 1). If your calcs are valid... make it so.

4) Sound like an excellent analogy... don't ignore it, but don't just blindly follow it either. See my response to Number 2).

See CALTRANS Trenching & Shoring Manual chapter on railroads. This is for temporary shoring... but I am absolutely certain that the same laws of physics, mathematics, and engineering principles apply to permanent walls, too.

Edit: I see that I failed to address one of your questions:

5) Is there a certain distance that the surcharge does not need to be applied to wingwalls?

5) No... but there will be a distance where it is reasonable (using engineering judgement to evaluate the results of calculations) to neglect surcharge loading on the wall.

Comment: You are asking pretty good questions founded on your own attempt to find answers, keep it up.

 

[DoubleStud]

For HS20 or HL-93, AASHTO made it easy for designers and we just add additional 2 ft of backfill to add the surcharge load (triangular load like water pressure). But in reality the load is more like a letter P shape. If you have a wing wall, it is also hard to figure out the accurate surcharge because more than likely your wall is in an angle, and the soil is also sloping. If I were you, if you dont do this very often, I would just do a ratio based on E-80 vs HS-20 load. Look at how long the wall is and use your engineering judgement on how many wheels you should include compared if it was a truck driving over. Then whatever ratio you have, just multiply it with 2 ft of soil. Then design the wall to have that additional soil. if you are having problem with sliding you can't solve, consider pouring slab to connect the two wingwalls.

 

[MTNClimber]

The E-80 loading is significant. I would recommend reviewing the CALTrans manual SRE posted. It’s very clear on how to approach the surcharge loading using a Cooper E-80 loading.

 

[PEinc]

wsengineer, I have worked on many railroad jobs for different railroad agencies. Every one required a Boussinesq live load surcharge analysis for Cooper E-80 loading. AMTRAK also required adding 50% for impact. In addition, each railroad also specified a live load influence line which determines when and where the live load surcharge is required. In my experience, railroad agencies are very particular about live load surcharges. I recommennd that you get a copy of your particular railroad's specification for surcharges. It will save you a lot of time and aggravation.

http://www.PeirceEngineering.com