Further Information

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• How can the vertical fingers be considered for a glued laminated beam?

New FAQ 004111 EN-US

In the main program RFEM/RSTAB, a member rotation of 90° is first required so that the lamellae of the glued-laminated beam are arranged on edge, see Figure 1.

To also consider the on-edge position of the beam in the design in the RF-/TIMBER Pro add-on module, increase the resistance for edgewise bending within the parameters set in the National Annex in the tab 'Other Settings 2/2', see Figure 2.

• RF-STEEL AISC add-module shows non-designable results for general cross-sections because of shear buckling checks according to Chapter G. How do I solve this?

New FAQ 003620 EN-US

When designing general cross-sections in the RF-STEEL AISC module, a "Non-designable" message is given for the design ratio. General cross-sections are defined in the program as user-defined sections or shapes which are not included in the specification. Though, some user-defined cross-sections can be designed under specific conditions. The warning message is displayed because shear buckling is not provided for general cross-section in the AISC 360-16 [1] Chapter G. More info on this topic can be found in the RF-STEEL AISC manual linked below.

This warning can be turned off in RF-STEEL AISC add-on module under the "Details" button > Shear Buckling > "Shear buckling warning for general cross-section."

• I have used the RF-/DYNAM Pro add-on module to generate the governing result combinations of seismic loads. What is the next way to perform a design of the individual components?

New FAQ 003598 EN-US

With the Equivalent Loads and Forced Vibrations add-on modules, you can create result combinations that contain the governing combinations of seismic loads. To perform a design with them, they have to be combined further on the basis of the extraordinary combination. This combination is defined, for example, in EN 1990 Art. 6.4.3.4:

${\mathrm E}_{\mathrm d}\;=\;\underset{}{\sum_{}^{}\;{\mathrm G}_{\mathrm k,\mathrm j}\;+\;\mathrm P\;+\;{\mathrm A}_{\mathrm{Ed}}\;+\;}\overset{}{\underset{}{\sum{\mathrm\psi}_{2,\mathrm i}\;{\mathrm Q}_{\mathrm k,\mathrm i}}}$

This accidental combination has to be defined manually in RFEM. Make sure that (for a direction combination with the 100/30% rule), both created result combinations from RF-/DYNAM Pro have to be added with the "Or" condition. A combination like this is displayed in Figure 02.

This accidental combination can then be used for further design. It is possible to evaluate the governing internal forces as well as to import and calculate this combination in the design modules.
• When calculating an RF-/JOINTS Steel - Column Base case, I get the message No. 48335 saying that the bending moment Mz exceeds 5% of the plastic moment resistance. What does it mean?

FAQ 003571 EN-US

The analysis of a rigid column footing is performed according to EN 1993-1-8 in the RF-/JOINTS Steel - Column Base add-on module. The standard only provides for simple bending in the design format. The design can be performed for compression only, tension, simple bending, or a combination of bending and tension, or bending and compression. If the note is confirmed with 'Yes', the add-on module performs all designs neglecting the unsupported internal force Mz.
• Why is the shear stiffness reduced to 10% in the RF-LAMINATE add-on module as well as for the material module orthotropic in RFEM for the shear modulus Gyz? In my opinion, the shear stiffness in slice plane Gxy would have to be reduced here?

FAQ 003351 EN-US

The reduction of the shear stiffness results from the fact that the fibers have a very small stiffness and a low strength perpendicular to each other. For this reason, the rolling shear strength of CLT panels is also very small.

For cross-laminated timber panels, glued sidewalls on boards are assumed. The boards are applied in the longitudinal direction along the x-axis of the coordinate system (Figure 2). For the shear stresses in Figure 2, the shear stress τyz is thus juxtaposed to the rolling shear strength.

The same applies to the shear stiffnesses. In the direction of the minor axis (yz plane), the stiffness of the individual boards is considerably smaller than in the direction of the principal axis (xz plane) and also larger than in the xy plane. The coordinate system shown in Figure 2 should be placed on the board in Figure 3.

• Which method of analysis is used for insulating glass?

FAQ 003330 EN-US

If there is an insulated glass unit selected for design in RF‑GLASS, the method of the large deformation analysis is set by default. Based on the existing gas volume in the space between glass panes, this method of analysis is also required and cannot be changed.

• Does Dlubal have some solutions for composite bridge construction or perhaps also verification examples or reference objects?

FAQ 003322 EN-US

Unfortunately, we do not currently have any solutions for the design of composite bridges in the program. Therefore, there are no verification or reference projects available for this.

Basically, models of composite bridges made of steel and concrete can be created in RFEM 5 and used e.g. for determination of internal forces in RFEM 5. Unfortunately, we are currently unable to offer any solutions for the design of such bridges according to the relevant standards.
• When determining the effective cross-section values according to EN 1993-1-1, EN 1993-1-5 or EN 1999-1-1, SHAPE-THIN displays the warning that the effective widths will only be determined for straight members. What does it mean?

FAQ 003232 EN-US

The cross-section class is defined according to EN 1993-1-1 and EN 1999-1-1 by the maximum width/width ratio c/t or b/t of the cross-section parts subjected to compression. EN 1993-1-1 or EN 1999-1-1 only list different straight c/t or b/t parts. Therefore, a classification and a determination of the effective widths is not carried out for curved c/t or b/t sections.

• Why is there only displayed the total reinforcement in the Results navigator under "Required Reinforcement", and not the top and bottom reinforcement separately?

FAQ 003074 EN-US

When designing one or more members with a circular cross-section, As,top and As,bottom are no longer displayed: For such cross-sections, "top" and "bottom" cannot be defined; the "circular" reinforcement is created, see Figure 01.

Solution: Create a separate design case for the circular cross-sections (select "File → New Case" in the module menu) and design the corresponding members separately. In the other design case, delete the members with circular cross-sections. After the calculation, As,top and As,bottom will be displayed in the Results navigator, see Figure 02.

• I have created new elements in my model, but they should not be subjected to the design, what can I do?

FAQ 003062 EN-US

In most cases, it is only necessary to add these new elements in the relevant add‑on module. Figure 01 shows that the "All" check box is not selected and therefore, the new elements have to be added manually.

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First Steps

We provide hints and tips to help you get started with the main programs RFEM and RSTAB.

Wind Simulation & Wind Load Generation

With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated 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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