In what case should Ld formula for tension be applied in columns? 2

[foxview11]

The contractor is insisting that Ld formula for tension is not applicable in columns because by doing it so, lapping is excessive for rebars with dia 32mm size. Our design department clearly specify that lapping shall be at mid height with tension splice of 1.3xLd. So that will make the lapping length of about 3.0m. But the clear height of the floor is 4.20m. So according to contractor, it is not practical to adopt such length. They want to use Ld in compression which is shorter. Please give your opinion regarding the matter.

 

[hokie66]

Interesting that the OP's calculated lap length is so long. I haven't checked the ACI code, but using the Australian code, AS3600, which is generally based on the ACI with some differences, I figure the tensile length for N32 bars to be about 1700. That is based on the OP stipulated 50 cover to the verticals and 28 MPa concrete. It also uses 500 MPa steel, our standard, which should give a longer lap than for 420 MPa. Is the 1.5 factor for epoxy coating at least most of the difference? Another reason to avoid epoxy.

 

[csd72]

hokie,

Yes epoxy coated rebar requires much greater lap length.