LRFD Empirical Deck Design Questions

[mike80]

I have two questions. Is the empirical method applicable to concrete decks supported on spread box beams?

Also, under AASHTO LRFD 9.7.2.4, it states the effective length to design depth must be between 6 and 18. What is the basis for the lower limit? If my ratio is close, say 5.46, can the empirical method still be used?

Thanks for any help on this.

 

[bridgebuster]

I would say so. You should just double-check your effective span width. I'm away from my office so I don't have access to the Code but I believe you should take the effective width as face to face of the boxes.

 

[bridgebuster]

The Kansas DoT has a forum that provides guidance on LRFD issues. If you register with them, they'll put you on their mailing list. You can also submit questions. Some questions on their site relate only to the KDoT position on the Code but there are many that are general interpretations.

http://www.ink.org

 

[mike80]

Thanks for the assist. (I have used the face to face dimension of the beams for my effective length.)

I will check out the KDOT site also for more info.