Wingwall contribution to resisting overturning

[GTEngr]

Hi,

I am checking the substructure design of a skew bridge with wing walls at varying angles to the abutments. I understand that the wing walls help to resist the overturning moment, but I am unsure of the calculations for this effect. What area of the wing wall should be considered and where is the moment arm taken from? Is it best to disregard them all together, or is that assumption too conservative?

Thank you

 

[dcarr82775]

The simplest way would be to look at it as a cantilever retaining wall. When you sum up the resisting moments, add the weight of the wing walls and accompanying resisting weights assumed to act at the centroid of the wingwall. That does of course assume the wing wall is tied into the rest of the wall sufficiently. The wing walls also only help resist overturning for some distance away from the corner. Once you get far enough away from a corner you really just have a pure cantilever.

Easiest to ignore them to start, and then add their affects only if needed.