huangyhg

wire mesh size
i just get a job to review the structural capacity of a one way concrete slab of a bew york city building, built in 1960. the major reinfocement is wire mesh 5 6 3 4-1/2. i need to know what is the meaning of 5 6 3 4-1/2 ?
thanks.
jccgrace
no other clues?
it's hard to be certain about the old nomenclature,
but i suspect the first numbers are mesh size (in.) and the second are wire size (gage).
for reference:
specifications covering welded wire mesh
astm a82 cold–drawn steel wire for concrete reinforcement.
astm a185 welded wire mesh for concrete reinforcing.
astm a496 deformed steel wire for concrete reinforcing.
astm a497 welded deformed steel wire mesh for concrete reinforcement
wire sizes were previously designated by american standard "wire gage numbers," but unfortunately there is no direct correlation between the old gage and modern "w" numbers. for example a "6" gage wire is equivalent to w2.9 (0.029 in.) wire.
style – spacings and sizes of wire in standard welded wire mesh are identified by "style". a typical designation is 6x12 w16xw8. this code denotes a welded wire mesh in which:
spacing of longitudinal wires = 6"
spacing of transverse wires = 12"
size of longitudinal wires = w16 (0.16 sq. in.)
size of transverse wires = w8 (0.08 sq. in.)
so 6 12 w16 w8
also try:
in the good days standard slab on grade reinforcing, in california anyway, was 6x6 - #10/#10 wwf. translation is 6"oc by 6"oc with #10 gage wire over #10 ga wire welded wire fabric (wwf). in your case this would mean 5"oc by 6"oc with #3 ga wire over #4 1/2 ga wire, which doesn't make sense. however, my 1973 version of the crsi manual of standard practice does list the call out as stated by escrowe, which would mean there is a wire gage of 4 1/2, which probably doesn't exist. however, once they went to the new terminology 6x6-w1.4xw1.4 (same mesh as 6x6-#10/#10), there is a w4.5 wire which had a diameter of 0.24 inches. i suspect you've got a blending of old and new designations which did, sometimes, occur. probably should find a damaged slab area and check the wire size and spacing just to be sure.
old ca se
i would read it as:
5 gauge @ 6"
3 gauge @ 4.5"
while doing the calculations is obviously a first step, i've had more success in getting the clients the "right" answer by doing full load tests on the slabs. i have them carry bricks or pockets of cement to get the equivalent factored live load
a lot of strange combinations of wwf were created in the past, not all symmetric in nature. you are just going to have to check some of the older publications.
personally, i don't know where bew york is either.
mike mccann
mmc engineering
it was never been an original engineerly structural reinforcement material, but was produced for different needs. - personally, i find 6-6/10-10 to be good for tomato cages since it lasts a long time (going on 20+ years), but is a little too stiff.
the referenced material may have been a very similar local material in that eara and area. since it is a wire mesh, trying to determine the present capacity of a 40 year old slab can be difficult.
take a few cores to dertmine the actual size and condition of the reinforcement if it can justify the professional analysis cost. - if it was a legally permitted building in new york city in 1960, there was some sort of permit or drawings to give you a lead as to the material specs. - they may not be what is really there.
dick

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