Post Tension Maximum Tendon Spacing

[struggle66]

Hi Everyone
Good Afternoon,

According to TR43, it will be 8 times slab thickness. My question is where does it come from and what is the concept behind this? Does it base on the assumption that the slab between the tendons acts as one-way slab and has adequate strength if the span is not more than 8 x slab thickness?

Thanks

 

[Retrograde]

assumption that the slab between the tendons acts as one-way slab and have adequate strength if the span is not more than 8 x slab thickness

I believe you are correct. TR43 states:

"Greater spacing may be used where it can be shown that the slab is capable of spanning between the tendons and supporting the applied design loads."

 

[struggle66]

Retrograde

Thanks,

I overlooked that sentence .

 

[rapt]

Struggle,

Yes, you can space them further, but you should then provide reinforcement transverse to the tendons to allow the slab to span that distance. For any spacing > 8D in a one way slab, you cannot just rely on concrete tensile strength for the slab to span between the tendons..

 

[Trenno]

Surprised you didn't mention serviceability issues there, RAPT.

 

[rapt]

Trenno,

Couldn't figure out how to get a reference to it in there!