concrete stair - nosing bars

huangyhg

concrete stair - nosing bars
folks,
what is the consensus on using nosing bars in risers for concrete stairs?
we have an ongoing debate in the office that these nosing bars do more bad than good. one school of thought says that the nosing bars are there to provide t&s reinforcement for the risers.
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with good details that ensure proper installation, i prefer to see a nosing than not. for apperance, as well as protecting the sharp concrete corner (tip). never heard nor thought of that it can be counted as t&s steel.  
nosing is good to prevent concrete spalling and excessive wear.  don't count as t&s reinf.
make sure it is non-slip nosing.
maybe i did not explain it correctly. it is a reinforcing bar used for the nosing.
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the (.) indicates the nosing bar. i am not talking about a nosing angle. it is a reinforcing bar provided below the nosing.
we use them and have never had a problem with them.  i'd be curious on what type of problems they could create.
they are unnecessary unless positioned at the bottom of the concrete step form for tension reinforcement.
the argument here is thus:
1. difficult to place - why place when there is no benefit?
2. when concrete cracks, these bars cause more spalling of the nosing.
also, exterior stairs in cold climates will be heavilly salted, and the nosing bars will corrode and cause spalling.  they are probably exposed to more salt due to their relatively exposed position in the concrete step.  with that said, i commonly see them in exterior stairs.  one way to deal with the salt induced corrosion is to specify a penetrating breathable water repellant like a silane or siloxane.
the nosing bar is utilized for construction purpose - to hold the parallel (longitudinal) bent bars together prior to, and during concreting. i don't think it causes cracks, or corrodes, more than other bars since it's farther away from the surface if installed correctly.  
i've encountered too many problems and have repaired stairs with nosing bars... don't use them!
they are difficult to place, cause a 'hard' point at the edge of a stair; this stress riser can cause the concrete to spall off at the nosing...  if not placed right, they're subject to chloride corrosion if deicing salt is used.
dik
i am in total agreement with dik! this question came up early in my career and we came to the conclusion to never use nosing bars for the reasons outlined above.