In the RF‑/STEEL EC3 add-on module, I obtain an extremely high design ratio for a member in the case of "Biaxial bending, shear and axial force". Although the axial force is relatively high, the design ratio seems unrealistic. What can be the cause?

Question

Accepted Answer

According to DIN EN 1993‑1‑1, Section 6.2.9, the moment resistance is reduced due to a high axial force utilization; thus, the maximum design ratio for the cross-section design "biaxial bending, shear and axial force according to 6.2.10 and 6.2.9" is unusually high.By using Equation (6.2) from Section 6.2.1 for the cross-section design instead of Equation (6.41) from Section 6.2.9.1, the design ratio can be reduced significantly.In the RF‑/STEEL EC3 add-on module, you can activate the linear interaction of the axial force and moment loading in the Details tab; see the image.

N_Ed	Design value of the existing axial force
N_Rd	Design value of the allowable axial force
M_y,Ed	Design value of the existing bending moment about the local y-axis
M_{y, Rd}	Design value of the allowable bending moment about the local y-axis
M_z,Ed	Design value of the existing bending moment about the local z-axis
M_{z, Rd}	Design value of the allowable bending moment about the local z-axis

High Ratios in Cross-Section Design

In the RF‑/STEEL EC3 add-on module, I obtain an extremely high design ratio for a member in the case of "Biaxial bending, shear and axial force". Although the axial force is relatively high, the design ratio seems unrealistic. What can be the cause?