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Re: Rebar Spacers in PC beams

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Bob,

No - the spacers are wired in with tie wire. I have never allowed welding of cages (and thankfully - have never been asked to).

Glen



My guess is that they are holding the spacers in place with tack welds. Are they following all of AWS D1.4 in the welding of these spacers? In many cases, they ignore code because "they are just tacks." Bad idea.

Bob Shaw SSTC





I've designed a conventionally reinforced precast beam with two layers of longitudinal tension reinforcement - specifically - 8 - #7's in two layers of 4 each. The design clear spacing between the two layers is 1". The beam is 12" x 13" and will be a composite tee-beam when the slab is cast on top.

The production crew has achieved the 1" clear spacing by placing a short stub of #8 bar between the two layers of longitudinal steel. This happens every 5 feet or so along the beam length.

Knowing that the concrete will crack (and crack control requirements are met), is there any problem with this method? I have never seen this done before in the tension zone of a beam. My experience has been that longitudinal bar elevs are set by tie wire hangers, and it looks odd to me to introduce a weakened plane in the tension zone of a beam. Would the solid bar/weakened plane cause normal flexural cracks to propagate further up the depth of the beam?

Thanks in advance.

Sincerely,

Glen A. Underwood, SE
Clark Pacific

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