Reinforced concrete design - Circular Section

[KkEngineer]

Dear All,

I am working on a concrete pile design and I have a question regarding the analysis of circular RC sections.

Which of the following methods is acceptable by Eurocode?

1. Column Interaction charts - If ok, should I refer BS for the charts?
2. Calculating stresses in the reinforcement layers - Could you provide me a good reference for the same?
3. Using an equivalent rectangular cross-section - Is this a reliable method?

Regards

Kk

 

[oldestguy]

You might be chasing a very old subject. This company has been around for some 100 or more years construction concrete piles. Maybe they can help.

http://www.raymondintl.com/

 

[IDS]

There is plenty of Eurocode stuff on the Internet, but unless I'm missing something Raymond don't seem to be a good source for it. They don't even seem to do piling any more, at least they don't mention it at the linked site.

In response to the specific questions:
1. If you can find Eurocode interaction charts they would be fine, but BS requirements are different to Eurocode, and different codes can give very different results for column capacity, so no, using BS interaction charts would not be a good idea.
2. Yes, calculating concrete and reinforcement stresses and forces is the basis of the code provisions. My spreadsheet RC Design Functions has a function that finds elastic stresses for a circular section under combined bending and axial load (Circe). There is another spreadsheet that will do arbitrary sections (including circular) under ULS loading, but it doesn't do Eurocode 2 at the moment. I'm sure there are other free and inexpensive alternatives available.
3. With the availability of modern analysis software, I don't see any good reason to use an equivalent square section, other than possibly as a quick rough cross-check.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[Ron]

Equivalent rectangular section is valid. Yes, there are other, more precise methods, but it is a good check on your section and reinforcement.

 

[KkEngineer]

Thanks for the responses.

Could you provide a good reference for the theory of analysis of reinforcement in circular sections?

Regards

Kk

 

[rapt]

There is no difference in the analysis of reinforcement in circular or rectangular sections. The difficulty comes in the calculation of the concrete forces.

Using an equivalent rectangle would not be very accurate.

Eurocode gives information of an equivalent concrete stress block that applies to circular sections.

Or you could use software that has been developed for this, eg RAPT's column module does circular RC and pre-tensioned piles!

 

[pappyirl]

The Concrete Centre have produced spreadsheets, one of which is for a circular column design to EC2 using the UK NA.