Culvert Endwalls

[2858]

For culvert endwalls with wingwalls, what height do you design for? Obviously, it would not be full height of the endwall. - It seems that the culvert area does not contribute to the force behind the wall as a typical retaining wall would. Also, it seems that the wingwalls are helping to support the endwall and vice versa.

In conclusion, it seems that the endwall would be way over-designed if it was designed as a full height retaining wall?

 

[shepherd]

2858,
How I've handled culvert endwall design is to provide columns at the ends of the headwall (looking in plan). The columns are placed on either side of the opening, and a construction joint is provided along one side of the column for the wingwalls to tie into. The headwall is then designed to span horizontally between these columns. Wingwalls can provide lateral resistance to the columns similar to shear walls depending on the angle it makes with the columns. Check out the FHWA website (

http://www.fhwa.dot.gov/bridge)

to find on line publications that show details for this type of arrangement. This arrangement is better suited for large headwalls that may transfer loads from traffic impact. For smaller headwalls carrying no traffic impact this arrangement wouldn't really be justified and an arrangement that is similar to a vertical wall pinned at the base free at the top usually will suffice (be sure to adequately tie the base of the wall back into the culvert top slab). I use the soil design pressure begginning with the culvert top slab for both arrangements. Hope this helps.

Shepherd