LRFD limits for max reinforcement dropped??
LRFD limits for max reinforcement dropped??
(OP)
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
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





RE: LRFD limits for max reinforcement dropped??
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.