AASHTO 5.14.5.3 - Effect of hogging/sagging moments on shear check

[JonnyFive]

Hi,

When you use AASHTO equation 5.14.5.3 which pertains to design for shear in slabs of box culverts - if you are checking the critical shear and it is at the location of a hogging moment (ie positive moment), you get an enhanced shear capacity?

Convesrly, checking shear at midpsan of the roof slab with sagging moements (ie negative moments) it reduces the shear capacity?

Or are these moment values meant to be considered as absolute values?

Regards,

 

[hokie66]

Not familiar with your code, but how can you have a critical shear condition at midspan? Something doesn't sound right here...shear is shear, regardless of direction.