Doug,
I am bored and working a holiday so forgive the uncouth behavior, but I have copied the part from AS5100-2004 and it states:
2.8 CRACKING
The cracking of beams or slabs under service conditions shall be controlled in accordance
with Clause 8.6 or Clause 9.4, as appropriate.
Where considered necessary for durability requirements, e.g., for exposure
classifications B2 or more severe, or
where crack width is considered detrimental to the appearance of the structure, consideration shall be given to limiting the steel stresses near the tension face to values less than those given in this Standard. In addition, in such conditions consideration shall be given to the detailing of the structure to minimize cracking due to restraint and shrinkage.
All concrete members shall be provided with a minimum of reinforcement as follows:
(a) For members with a thickness of 150 mm or less, a single layer of reinforcement of
not less than 500 mm per metre for each of two directions, at right angles to each
other.
Reinforcement provided for structural reasons can be considered as contributing
towards this requirement.
(b) For members with a thickness greater than 150 mm, each face of the member shall be
reinforced with not less than 500 mm per metre for each of two directions at right
angles to each other. The layers shall be placed as close to each surface as cover and
detailing permit.
Reinforcement provided for structural reasons and located within 80 mm of the face
can be considered as contributing towards this requirement.
Reinforcement shall be provided in two directions at right angles to each other and with a
spacing that is less than or equal to 300 mm.
The requirements of this Clause in relation to the quantity of reinforcement in a particular
direction may be relaxed if the member is unrestrained against longitudinal movement in that direction and the effects of differential temperature and humidity are minimal.
From the underlined areas it would appear permissible by this code to leave out top reinforcement. Interpretation of the clause is interesting because it appears that the "all concrete members" statement is separate to the above wordings, but it could be argued either way, but I am sure the end of the clause is fairly clear that unless you have a need for the reo, you don't need it.
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."