PT Slab live load reduction? 1

[seattlemike]

Banded tendons in PT slab design are meant to support a wide area, so it seems live load reduction per IBC could be acceptable?

Is that correct? What do you think?

 

[rapt]

seattlemike,

PT 2way slabs with banded/distributed tendons are still 2 way slabs. The tendon layout is relying on a yield line solution to justify the overall slab strength.

The load path provided is actually a one way solution because that is how the tendons have been layed out but it is still really a 2way slab and must be treated as one for loadings.

Also, LL reduction for slabs has been discussed before and I know US engineers do it, but have you considered the effects on construction cost if it is a multi-level building. Back-propping requirements are much more severe if LL reduction has been used in the design of slabs and beams. We have decided the extra construction cost and inconvenience outweighs any savings from LL reduction.