Distribution factor for exterior open box beam

[neznajko]

AASHTO tells you to use lever rule when determining the forces in exterior open box beam.

Where should I put the the supports to apply the lever rule?

For the first support, should it be the CL of the exterior web or CL of the beam? For the second support - - CL of the second girder, CL if the "exterior" web of the second girder, CL of the "interior" web if the first girder?

In NCHRP 592, Appendix H, there is a table (attached), which does not make it more understandable to me
Unfortunately in all examples I found the DF is shown for the typical interior beams only.

Thanks

 

[neznajko]

Well, I guess this from TxDOT answers the question....

 

[Lomarandil]

Good question neznajko. Thanks for following up -- I'm not sure how I would have handled it either.