#### Further Information

In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.

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• ### Is it possible to calculate and design 5G transmission towers, antenna towers or towers with Dlubal Software?

New FAQ 004256 EN

The programs RFEM or RSTAB are very well suited to perform these designs . Add-on modules for steel or solid construction support your individual solutions.

Special add-on modules from the RF-/MAST series extend and simplify the possibilities.

###### Basic programs RFEM or RSTAB
The basic programs are used to define structures and materials as well as actions.

With RSTAB, you can edit and calculate truss-like or frame-like structures. RFEM also allows for plate, slab, shell, and solid elements.

RF-/TOWER Structure
helps in the efficient generation of three- or four-sided tower structures

RF-/TOWER Attachments
includes a comprehensive library with add-on parts and allows for a quick and easy integration into your model.

supports you professionally in the generation of wind, ice and traffic loads.

RF-/TOWER effective lengths
determines the effective lengths of members especially for masts

RF-/TOWER Design
does the design according to EN 1993-1-1, EN 1993-3-1 and EN 50341 incl.

RF-/JOINTS Steel Tower
designs hinged bolt connections of lattice towers according to EN 1993-1-8

###### Wind analysis in a digital wind tunnel
Use RWIND Simulation for advanced flow behavior analyzes. The results can be used directly as loads or load cases in RFEM or RSTAB.

###### Dynamic Analysis
If earthquake calculations or vibration analyzes are necessary, the RF-/DYNAM Pro add-on modules provide suitable tools for determining natural frequencies and shapes, for analyzing forced vibrations, for generating equivalent loads, or for nonlinear time history analysis.

• ### Is it also possible to simulate an external steel structure in RWIND Simulation?

New FAQ 004175 EN

Yes, the RWIND Simulation program is generally designed and can implement any model of RFEM or RSTAB.

For a steel structure consisting of pure member elements, the program creates a coherent, voluminous envelope of the member surfaces for the numerical wind tunnel. The result of this modeling for the simulation depends on the available cross-sections and the mesh settings. Due to the wind current, corresponding surface pressures result on this surface layer.

After having calculated the wind flow, the program sums the surface pressures of the member units and returns a corresponding equivalent load (single, uniform, or trapezoidal) for each member axis.

These loads are applied in RFEM or RSTAB for the further calculation of internal forces.

• ### How can the real cross-section geometry of member elements be considered in the RWIND Simulation?

New FAQ 004165 EN

In RFEM, the interface application 'Simulate and Generate Wind Loads' makes it possible to exchange member, surface, and solid elements, and in RSTAB to exchange the member elements.

To avoid generating a too fine mesh along with a corresponding long calculation time, the program simulates all members with a rectangular cross-section as standard. The size of the rectangular cross-section is selected in such a way that the real cross-section geometry is barely included.

By deactivating the option 'Export Optimized Member Topology', you can avoid this additional optimization of the model and allow consideration of the real cross-section geometry within existing cross-section settings.

If the exact representation of the cross-section geometry requires more than 1000000 elements, the interface automatically changes to the simplified rectangular section display of the cross-sections.

• ### Is it possible to design a 'Kármán vortex street' behind an object in the numerical wind tunnel of RWIND Simulation?

New FAQ 004163 EN

The program RWIND Simulation implements a stationary flow calculation for non-compressible gases. The laws and wording used in this way do not change over time. Thus, the calculation outputs a result set without temporal variation.

[1] The effect of a 'Kármán vortex street', in which counter-rotating vortices develop behind a body around which flows, results in a temporal change of the flow effect. Therefore, this fluid-mechanical effect cannot be simulated in RWIND Simulation.

• ### I wish to integrate a circular hole plate in an aligned way. Is it possible to generate such an aligned mesh in RFEM?

FAQ 003461 EN

With the FE mesh refinement, it is also possible to create an aligned FE mesh in the program. Thus, the automatic FE mesh generator can be controlled to a certain extent. However, it is not possible to use it for setting of a specified mesh geometry.
• ### The upper and lower flanges must be butted over a column, but the verticals and diagonals are connected to the flanges.How do I arrange the hinges?

FAQ 003368 EN

If the flanges are not continuous and the diagonals are fastened to the flanges, it may be necessary to insert an intermediate member.

Figure 1 shows a system where the flange is not continuous but the diagonals are rigidly connected to the flange. To transfer the diagonal moments to the flange, the diagonal must arrive in the flange before the impact, otherwise the moment of the diagonal will be transferred to the opposite member (see Figure 2).

If the diagonals are also connected by hinges, you can do without the intermediate member. Please note that at least one member is not hinged so that the connection node can not rotate freely (see Figure 3).

If a vertical is used, it must either be connected to one of the two flanges or between both flanges. In both cases, the model from Figure 1 is suitable and has to be modified accordingly. Figure 4 shows the model with a vertical between the flanges and Figure 5 shows the variant with the vertical on the right flange.

• ### Is it possible to view the intermediate steps for determining the wind load, e.g. the fineness coefficient , in RF-/TOWER Loading?

FAQ 003355 EN

In the module's results tables, you can find all intermediate values depending on the wind direction and the side as well as the section. This function is also available in the long version of the report, but can significantly increase the size of the report.
• ### When calculating a cable using the STEEL EC3 add‑on module, he error message "Incorrect characteristic stresses for material No. 1! Please correct this in Table 1.2." appears.

FAQ 003110 EN

For the "Cable..." material, there are no entries for yield strength and tension resistance stored in the library (see Figure 02). Therefore, the calculation basis for these members is missing in the add-on module. In order to be able to design such materials, it is necessary to create a new material and, provided that the information from the manufacturer is known, add the missing parameters manually.

• ### How do I combine the effects of the wind load acting on a guyed mast, which consists of mean wind loading and a patch load, according to the standard EN 1993‑3‑1 B.4.3.2.5 (1)?

FAQ 003104 EN

Chapter B.4.3 of the standard EN 1993‑3‑1 describes the equivalent static method to analyze the dynamic response to wind turbulence.

The patch loads describe the fluctuating wind components.

${\mathrm S}_{\mathrm{TM}}={\mathrm S}_{\mathrm m\;}\pm{\mathrm S}_{\mathrm p}$

${\mathrm S}_{\mathrm p}=\sqrt{\sum_{\mathrm i=1}^{\mathrm N}\left({\mathrm S}_{\mathrm i}-{\mathrm S}_{\mathrm m}\right)^2}$

where
i is the number of the actual spans
N is the total number of load patterns required (actual spans i)

• ### I have designed a steel connection using RF‑JOINTS and then created a model to compare it in RFEM. Why are the results not identical?

FAQ 002505 EN

RF-JOINTS performs an idealized design of a steel connection according to the standard, which cannot be easily compared with an exact FE calculation.

Thus, the following conditions must be met:

• Consideration or exclusion of friction/compression/tension within the contact solid (tab 'Solid') as well as for the bolts modelled subsequently
• Consideration of internal forces and deformations within the subsequently modelled end plates or similar, which causes redistribution of bolt forces in the FE calculation (in contrast to the idealized design in RF‑JOINTS)
This can be corrected by rigid connection objects, for example (an end plate as a rigid surface).
• Uniform load introduction into the FE model, for example, by using rigid members or rigid surfaces as described in the article 'FEM Modeling Approaches of Rigid Connections'

If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.

#### 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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