Robin Johansson, Konstruktör at UBAB, on why the general method changed how they design concrete columns.
EN1992-1-1 defines three methods for calculating stiffness in concrete columns under second-order effects. Two of them — nominal stiffness and nominal curvature — are simplified. They are widely used.
For a slender column at a low reinforcement ratio, they can also demand up to 300% more reinforcement than the general method for the same section under the same load.
The reason: simplified methods apply a fixed stiffness reduction regardless of actual section behavior. The general method calculates stiffness directly from the section response.
→ Full technical comparison: Concrete Stiffness – The General Method
Ubab's Situation
Ubab is a Swedish supplier of prefabricated concrete elements. Their structural engineers design columns and beams daily.
Why they Switched
Robin Johansson’s previous tool calculated concrete columns using the simplified method. The general method was not available.
"They don't use what you call... the general method," Robin says of the software they moved away from. "So that's one improvement."
Switching took less than two days.
"For me I would say a day or two. Pretty easy to use. Pretty easy to learn."
What Changed
Robin Johansson designs columns for a living. When asked where PolyColumn makes the biggest difference, he doesn’t hesitate:
"For columns, it's the general method, I think."
Ubab hasn’t run a formal comparison against their previous software. But they don’t need to — they can feel it in the output.
"We feel that we get a little bit less… reinforcement."
For a 5.5m column under typical loads, “a little bit less” is up to 300%. It adds up.
The Point
Most calculation tools default to simplified methods — they are easier to implement.
PolyColumn implements the general method as standard, for both uniaxial and biaxial bending.
If your current tool is not using the general method, you are likely adding reinforcement you do not need.
Download PolyColumn · Read the technical article
Robin Johansson is a Konstruktör at Ubab, a Swedish supplier of prefabricated concrete elements.