Posted By ICFBdr on 19 May 2011 02:05 PM
It is not that an 8" x 8" column CAN'T support the load - it is simply the fact that most manufacturers require a minimum 12" between openings. If you want to/need to build with less, an engineer is required.
ICFBdr explains it pretty clearly here. When a manufacturer puts out a generic carefully conservative rule for their system -- e.g. design lintels as if it is a continous opening if columns are smaller than 1 foot etc., etc. It has little to do with what you can accomplish with an engineer. Use of an engineer allows you to accomplish amazing things with concrete. Your not going to find that flexibility in a generic manual from a manufacturer. Don't confuse these high level rules of thumb from a manufacturer with engineering. For obvious reasons they have extremely high factors of safefy added on.
Granted a good 8"x8" column will need strirups for strength in tension but it's not going to need much help in compression. E.g. 4000 psi concrete with 64 square inches - you do the math. Regards.