reinforced concrete box design strip width

huangyhg

reinforced concrete box design strip width?
1992 aashto sec.17.6.4.3 provided that "the width of top slab strip used for distribution of concentrated wheel loads may be increased by twice the box height for the distribution of loads to the bottom slab."
1994 aashto sec.12.11.2.2 provides that "the width of the top slab strip used for distribution of concentrated wheel loads shall also be used for the deterimination of moments, shears, and thrusts in the side wall and the bottom slab"
normally when a concrete wall is loaded, the load is assumed to be distributed in a triangular method down the wall, the old "60 degree" rule. does anyone have an idea as to why the change?  the best i can get out of the local dot is "duh".
thanks, tincan
have you contacted aashto?  what was their response?  i would expect that such a severe change would be covered by the commentary to the 1994 edition.
focht3,
have corresponded with aashto but on reply to date.  there was no commentary concerning the strip width in the aashto spec book.
tanks for the reply.