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Moment-Stiffness-Curvature

The Moment–Stiffness–Curvature chart shows the variation of curvature and bending stiffness of a section with increasing bending moment, for a specified bending direction and axial force.

Moment-Stiffness-Curvature-Chart-Example.

What the chart shows​

  • Moment (M). On the horizontal axis, the resultant bending moment at a user-specified angle.
  • Curvature (κ). On the primary vertical axis, the interpolated SLS curvature corresponding to the applied moment and bending direction.
  • Stiffness (EI). On the secondary vertical axis, the effective (secant) bending stiffness, calculated as: EI=M/κEI = M / κ

How to use​

The chart is intended for serviceability limit state (SLS) assessment, for example:

  • Identifying the cracking moment.
  • Identifying an appropriate equivalent bending stiffness for displacement calculations.
  • Understanding stiffness reduction due to cracking.
  • Comparing section behaviour for different axial forces or bending directions.