Pipe filled with grouted 3/8" Cable

[gkujawa]

Hello,

I am analyzing a self support communication tower that has been modified such that the existing pipe legs have been filled with non-shrink concrete grout and a 3/8" EHS Cable.

For the tensile capacity of the pipe section, would I consider the entire contribution of the cable's tensile strength in calculating the pipe's tensile capacity?

Thanks.

 

[BAretired]

Not likely, because the pipe will yield before the cable reaches its tensile strength.

BA

 

[BAretired]

Not likely, because the pipe will yield before the cable reaches its tensile strength.

BA

 

[Ron]

No. At best, the cable is likely pre-compressing the tube. While that gives you some additional tension, you don't know how much without knowing the stress in the cable.

If the cable is in the grout for the purpose of additional tensile reinforcement, I agree with BAretired.

 

[chicopee]

What is the purpose of the cable in the self supporting tower? I am confident that it is not for post tensioning in such tower.

 

[gkujawa]

Thanks for the input.

My situation is that my leg section is at 106% of the tensile capacity without considering any contribution from the cable. The pipe does yield, but could we consider the pipe + cable as a composite section, with the cable contributing to the tensile resistance provided by the pipe?

I don't have the original modificaiton drawings, so I am going a bit in the dark as to how / why the cable was added.

 

[BAretired]

The cable will contribute to the tensile capacity of the combined section but not very much. It is probably fair to say that the tensile capacity of the pipe plus cable is equal to (A_p + A_c)F_y(p) where subscripts p and c refer to pipe and cable respectively.

BA

 

[gkujawa]

Thanks BAretired! I was thinking along those lines after pondering a bit.

 

[oldrunner]

Do you know whether the cable is tensioned? There's are big difference in the modulus of elasticity of the cable and even if the cable was prestretched before installation. I have heard of people considering this kind of action before - possibly in the Southern California area, but I could never get the statics to work or be effective.

 

[gkujawa]

I don't know if the cable is tensioned. I unfortunately don't have the drawings which include the installation of the cable.