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Bending, Shear and Axial force

The influence of the Shear force, Axial force on the Bending resistance is accounted for according to SIA 263 depending on the classification:

Class 1,2: art. 5.1.7 & art. 5.1.8

Class 3: art. 5.2.7 & art. 5.2.8

Class 4: art. 5.3.7

Reduction factor Rho_y for weak axis bending resistance

There is no reduced bending moment resistance formula specified in SIA 263 code in case of high shear force V_y,Ed>0.50*V_y,Rd in combination with a weak axis bending moment M_z,Ed. In order to prevent the use of the von Mises yield criterion SCIA Engineer uses the reduction factor Rho_y in order to still use the combined section check formulas defined in SIA 263.

Rho_y is defined in EN 1993-1-1 art. 6.2.8(3) and it is used for reducing the yield strength (on the whole cross-section area) in order to obtain a reduced bending moment resistance M_z,Rd.

By default the setting Apply reduction factor Rho_y in case of high shear forceis activated in the steel setup.

If it is deactivated in the steel setup the von Mises yield criterion will be used for that usecase.

von Mises yield criterion for the combined section check

In case of one of the following, the influence of the Shear force or Axial force on the Bending resistance cannot be accounted for using the specified article:

• No plastic shear resistance is available.
• Elastic check only is executed.
• Due to extreme shear (V_Ed > V_Rd) which would lead to a negative reduction.
• In case there is no corresponding bending moment the reduction for shear cannot be applied (for example V_z,Ed combined with M_z,Ed and thus no corresponding M_y,Ed).
• In case of high shear force in which the cross-section is not an I-section (FC1) or an RHS-section (FC2).
• In case of high shear force V_y,Ed (with corresponding bending moment M_z,Ed) in which the steel setup setting "Apply reduction factor Rho_y in case of high shear force" is not activated.
• If N_Ed > 0.9*N_Rd
• If Torsion is present.
• If the cross-section has a Class 4 classification in which the internal forces are not only M_y,Ed and V_z,Ed.

In each of those cases an elastic verification using the von Mises yield criterion according to art. 4.3.5 will be done instead.

Below you can see an overview of the decision making process for the combined section check:

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