Question:
I get a message in RF‑/PLATE‑BUCKLING saying that the distance between stiffeners exceeds the minimum requirement. What should I do?
Answer:
The message shown in Image 01 is displayed if you select the "Minimum distance between stiffeners: 30 ε t" check box in Details and the clear distance between the stiffeners is smaller than this minimum distance a-min. The minimum distance is calculated as follows:
a-min = 30 ⋅ ε ⋅ t
where:
ε = √ (235 / f-y [N/mm²])
f-y ... Yield strength ... Thickness of the buckling panel
In this case, the distance of the stiffeners must be increased in Window "1.2 Stiffeners". For the buckling panel shown in Image 01, the clear distance between the stiffeners is:
Δz = z-2 - z-1 - (t-1 + t-2) / 2= 890 - 600 - (10 + 10) / 2 = 280 mm
This distance is smaller than the minimum distance:
a-min = 30 ⋅ ε ⋅ t = 30 ⋅ √(235 / 355) ⋅ 12 = 292.9 mm
Therefore, the position of Stiffener 2 should be entered at least
z-2 = z-1 + (t-1 + t-2) / 2 + a-min = 600 + (10 + 10) / 2 + 292.9 ≈ 903 mm
This distance is also displayed as information in Window "1.2 Stiffeners" when placing the mouse pointer over Stiffener 2 (Image 02).
If the calculation should also be performed for a stiffener distance smaller than the minimum distance, the "Minimum distance between stiffeners: 30 ε t" check box must be deactivated (Figure 03).