Required footing reinforcement using ACI vs BS

[rteja]

Hi,
The projects our company does, requires shallow foundation pads for some structures like flag poles, totem sign etc. We are currently outsourcing the design calculations, but i'm learning more about foundation design, and want do the calculations myself in future.
I crosscheck my analysis using prokon software and i noticed that the reinforcement requirement when setting the design code to ACI is much higher (almost 2X) when compared to british standard. (for the same loads)
can someone please explain the reason behind this? why this huge difference in reinforcement requirement?

Thanks.

 

[RPMG]

ACI set the minimum based on a thought experiment about ductility. No testing was done. They equated Mn.plain to Phi*Mn.reinforced, and set that area of steel as As,min. The idea is that plain concrete behaviors can be eliminated with this As,min. However, that's illogical because increasing the depth of a footing will always increase the flexural strength, and it doesn't provide any guidance for existing structures.

Maybe the Brits put their pencils down and broke some concrete.

 

[JoshPlumSE]

My belief is the ACI requirements are really geared towards elevated slabs which are much thinner. The requirements (IMO) don't make much sense for thick footings and foundation slabs.