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• ### How can I apply a linearly variable load in Z, such as earth pressure, to a rotated surface in the form of a hopper, which acts in the XY plane, but is oriented to the central axis of the rotated surface?

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For a cylinder, the load direction could be defined locally in z, but for a hopper, the load would no longer be parallel to the XY plane.

Therefore, such a load must be divided into two components (X and Y), with the "Global related to the projected area" load direction, once XP and once YP, as well as the "Linear in Z" load distribution, see the image:

The load value may have to be converted.

• ### How can I model and design a crane runway girder with Dlubal Software?

For the modeling and design of crane runway girders, we offer the stand -alone program CRANEWAY .

• ### I have selected all available members for design in RF-/TIMBER Pro. Why are tapered members not designed?

Presumably, the option "Design of stress points also for solid rectangular and round cross -sections" is activated in the details.

Since the design of stress points is not allowed for tapered members, this function must be deactivated, see the figure.

If this option is to be considered despite the existing tapered cross -sections, the tapered members have to be treated in a separate design case.

• ### Why does the vertical position of a result member in my model have no influence on the bending moment My of the member?

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The change of the vertical position or an eccentricity has an effect on the bending moment My only if there are other forces acting on the model, which are included in this moment, such as the axial force in the following example.

A slab, supported as a single-span beam, is only loaded vertically on the left in the image. The bending moments of the result members positioned above and below the slab do not differ.

On the right, the slab is additionally loaded by an axial force. Therefore, the result members obtain additional negative or positive moments. The eccentricity acts as a lever arm.

• ### Why do I get large differences for the design of a longitudinally stiffened buckling panel in comparison with the German and Austrian National Annex?

According to the national provision of ÖNORM EN 1993‑1‑5:2007, Section 4.5.3(3), it is possible to abandon the increase of σcr,c, allowed in the note, with respect to the elastic critical buckling stress σcr,sl of the longitudinal stiffener adjacent to the compression edge as this results in very conservative results with regard to the resulting reduction factor ρc for the buckling analysis according to ÖNORM EN 1993‑1‑5, Section 4.5.4(1), Equation 4.13. Image 01 shows an example of a longitudinally stiffened buckling panel, designed according to the Austrian National Annex.

In DIN EN 1993‑1‑5, the note given in Section 4.5.3(3) applies, so it results in the following difference, see Image 02.

• ### How can I perform the stability analysis in RF‑/STEEL EC3 for a flat bar supported on edges, such as 100/5? Although the cross-section is rotated by 90° in RFEM/RSTAB, it is displayed as lying flat in RF‑/STEEL EC3.

In RF‑/STEEL EC3, the uniaxial bending stress is always related to the local y-axis of a member and the local y‑axis of a member is always assumed as the major axis in the case of symmetric cross-sections, therefore it is only possible in such a case to change the cross-section description from "100/5" to "5/100", see the image. Thus, the stability analysis is performed accordingly.

• ### How can I change the colors of the selection and preselection?

The colors of the selection and preselection can be changed within the display properties:

• Menu bar "Options" → "Display Properties" → "Edit"
or shortcut menu (right-click on the work plane) → Display Properties
• Colors → Other → Selection/Preselection, see the image

• ### How is the rotational stiffness of a buckling stiffener determined in PLATE‑BUCKLING?

In PLATE‑BUCKLING, the rotational stiffness of a stiffener is determined on the basis of the sketch shown in the figure including formulas according to ECCS Design of Plated Structures, Fig. 2.77.

• ### Is it possible to manually specify a longitudinal reinforcement for design in RF‑PUNCH Pro?

Yes, the RF‑PUNCH Pro add-on module allows for defining the desired longitudinal reinforcement in the "1.5 Punching Nodes" window, see the image.

If you want to consider the minimum moments when calculating the reinforcement for columns, you can also activate this in the add-on module as described in FAQ 004371.

• ### After the design with RF‑/TIMBER Pro, I optimized a cross-section. Why is the utilization of the optimized cross-section exceeded now?

The optimization of cross-sections in RF‑/TIMBER Pro is based exclusively on the ultimate limit state (ULS), not the serviceability limit state (SLS), see the image from the RF‑TIMBER Pro manual.

More information about the cross-section optimization can be found in the RF-TIMBER Pro manual on pages 76-78 (also available with the F1 key in the add-on module).

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Wind Simulation & Wind Load Generation

With the stand -alone program RWIND Simulation, you can simulate wind flows around simple or complex structures by means of a digital wind tunnel.

The generated wind loads acting on these objects can be imported to RFEM or RSTAB.

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