equivalent rectangular section for a round concrete beam

huangyhg

equivalent rectangular section for a round concrete beam
hi everyone,
what is the best fitting equivalent rectangular section for a circular concrete beam?
i am designing a concrete pile which is loaded laterally. the pile has circular cross-section but i design it as a rectangular beam. i do have some hand-outs giving some equivalent rectangular beam dimensions for each diameter but i was wondering if there is any academic/practical article which would give a scentific based solution for this question.
solve for the bending strength of the circular section with associated reinforcement.  compare to a square section with the bending about the diagonal.  this is the weakest axis for the square section with equal steel in all four faces.
i have seen a book that mentions this, i will get back to you tommorow with the name of the method.
i don't believe there is any recognized conversion.  hate to say this, but you probably whould be analyzing these piles as circular sections.  if one were to fail, you'd have a hard time defending a conversion analysis thats not officially recognized.  crsi publishes a calculation method for circular sections in the crsi handbook.
it is called the charles whitney method from 1942.
2 layers of half the reinforcement 0.67ds apart, and a concrete section 0.8d deep by (as/0.8d) wide?
this is an approximation, and as such you should always ensure that you have at least 10% or so up your sleeve for any inaccuracies. i would also not that i imagine it would be very inacurate if there were any significant axial loads.
you really need some design charts in this country, this problem would be done in 5 minutes with circular column design charts (like the ones i used in australia) i havent seen any here.
check out this web site to see if you can find a spreadsheet (check it before you use it):
aren't interaction charts available for circular sections?  do you not have a program such as enercalc?  it will design the reinforcement for a circular section rather quickly.  i did this recently.  the only conversion i had to make to a "rectangular section" was during the shear checks.  there is no clear 'd' for a circular section.  at that point, for the shear check, aci gives guidance in 11.3.3.  
if you don't have a program like enercalc to design the flexural reinforcing, i would look for those interaction charts for circular sections.