Foundation: Prestressed Concrete Pile Design

[kowheng]

[lambert]

What code of practice does the spreadsheet follow sir??? Is this applicable for solid, round or octagonal sections???

[kowheng]

This spreadsheet was designed for general case.
Allowable stresses can be inputted as you want and conforming to code you use.
Any section can be design, because you have to input Area(Ag), Moment of Inertia(Ig), and Section modulus(Zg) yourself.

[lambert]

Sir, I had capsulized my queries about your spreadsheet. Please help me to understand it very well because I'm not well knowledgeable in allowable stress design. I'm using Strength Design since I practice Civil Engineering. The following are my questions:

1. What is PS,HS,PI and DH stand for?.
2. Is there a general rule to estimate fci' at transfer, fci at transfer and fc at service given fc'?
3. How to determine the maximum allowable prestressing force (in kN) so that the prestressing steel will not break? Is this the same with the breaking strength on ASTM Standard?
4. How can we know if the section can adequately support the given bending moment (if there is)???. Is it by performing interaction diagram like in R.C.???

I'm using ACI and AASHTO as reference code.


Regards

[jacs127]

Dear Friend,

Please refer "Prestressed concrete Design" by Gerwick in which a particular chapter is devoted for prestressed pile design which will help you to understand almost every thing you want. The book is already available in the forum.

[lambert]

Friend,

I need a brief answer to my queries for now due to lack of time to read such reference.


Regards

[kowheng]

@lambert

1. What is PS,HS,PI and DH stand for?.
It is just name of different pile type. You can define it with your own way. The table stored these values is designed for your convenience. You can ignore it if you input Ag, Ig, Zg manually.

2. Is there a general rule to estimate fci' at transfer, fci at transfer and fc at service given fc'?
From my experience together with codes in my home country(Thailand), fci = 0.6·fci' and fc = 0.45·fc'

3. How to determine the maximum allowable prestressing force (in kN) so that the prestressing steel will not break? Is this the same with the breaking strength on ASTM Standard?
Yes, it is the same.

4. How can we know if the section can adequately support the given bending moment (if there is)???. Is it by performing interaction diagram like in R.C.???
No interaction diagram, just check it as beam. Critical moment, practically, is at transportation stage.

[lambert]

Sir Koweng,

I have one (1) question left. How to determine the moment factor for transport moment for example if we have 1, 2, 3 or 4 pick-up points???

[kowheng]

@lambert

Do your own analysis.

[lambert]

How do we handle the case (i.e. pile capacity) when the unsupported length of the pile like in a marine structure is very high, for example the klu/r is equal to 120???

Regards,
Lambert

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How do we handle the case (i.e. pile capacity) when the unsupported length of the pile like in a marine structure is very high, for example the klu/r is equal to 120???

Regards,
Lambert