Improvement of interaction check

Interaction check verifies a cross-section capacity to carry additional forces due to shear and torsion in longitudinal reinforcement. Resistance of shear reinforcement is checked for the combination of shear and torsion. 

The cross-section can be subjected to the normal force, bending moments, shear forces simultaneously. In complex structures such as bridges, even another component, the torsion moment, can act in the cross-section. That is why we need to take all these components into account and check the cross-section capacity. In the previous versions of IDEA StatiCa RCS, the increment of stress/strain calculation was based on the rebar's linear-elastic behavior assumption (we didn't respect the plastic branch of the stress-strain diagram of rebar). 

With version 21.0, real axial stiffness and tensile strength are respected. Therefore, each rebar's actual stress-state is captured, and increments due to shear and torsion are calculated based on their nonlinear stress-strain diagrams. The deformation compatibility of the group of rebars is respected. 

Practical application:  Combination of rebars with different material properties (such as Young´s modulus, tensile strength) – shear reinforcement can be designed as stirrups combined with prestressing bars (initial stress by prestressing is not defined in this version).

Interaction check also applies to longitudinal reinforcement. The additional tensile forces due to shear and torsion are added to the stress state caused by normal force and bending moments. In some cases, a limited interaction check according to EN 6.2.3 (7) can be applied. When this limited check was considered, the additional tensile forces were neglected from both shear and torsion in older versions. This approach led to the fact that a limited interaction check cannot be used if the cross-section is subjected to a torsional moment in addition. And thus unsatisfied check for the interaction. Now, the interaction of normal force, bending and torsional moments can be checked. No more unsatisfied interaction checks!

Available in Expert and Enhanced edition.