Hello, to answer the question directly, yes indeed.  The main advantage can be obtained by the stirrups.  By reducing the spacing between them you'll arive at confined concrete and therefore higher concrete pressures are possible.  By fixining each rebar in two directions (look earthquake regulations) the best effect will be obtained.

Tom

Hello Shyam

As Tom said, the simple answer is yes. The number (therefore spacing) and arrangement of the rebars can affect the compressive strength. I

Dear Shyam

If you mean longitudinal reinforcement, I would say no, unless they provide a confining action to the concrete.  

Thank you for the answers, i was mainly wondering if there is any research out there or if anyone knew what would happen if 2,3,4 bars were acting as one bar within an arrangement, say for instance you had 2H12 bars at the top and 2H16 at the bottom of an arrangement, however you replaced one of the bottom H16 with 2,3,4 bars with the same area as the singular H16, and tired all these bars together creating one, what would happen? 

Do what I would do make a few - test them and publish the results

Thank you John, that is what i will be doing, just getting some background information first 

The answer is dependent on whether the tests are dynamic or quasi-static -- dynamic will give you a lower load as the material sheds during the cycles. 

But as Baker observed fast loading giving higher results 

Theoretically, it will not make any difference because when you put the area of steel in any equation, you will calculate the total area of steel bars ( either tension OR compression ) regardless of the arrangement. In numerical analysis (FEA) and experimental analysis as I know it will make a difference.