LRFD limits for max reinforcement dropped??

[TpaRAF]

I have a prestressed flat slab design that exceeds the older c/d limits.

In the latest edition of the AASHTO LRFD Bridge Design specs, the check for "c/d < 0.42" has been dropped [§5.7.3.3]. The code appears to address this by applying a reduction to the phi factor when the section is over-reinforced [§5.5.4.2].

This implies the moment capacity should be reduced when the section becomes over-reinforced.

Am I interpreting this correctly? It just seems too easy to say "forget-about-it" and skip this check.

Thanks! RAF

 

[Dinosaur]

If your facts are accurate, then my conclusion is ...

OK Mr. Engineer, if you think putting this much reinforcement is the right way to go, then your going to pay a penalty since you no longer have a ductile failure mechanism.

If in your opinion, increasing the thickness and maintaining a ductile failure mode are acceptable, then by all means go ahead.