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.
Frequently Asked Questions (FAQ)
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According to EN 1991‑1‑3, the snow load must be multiplied by the factor of 0.8 for the snow load on a roof. Therefore, the following load results:
sk = 5 kN/m² × 0.8 = 4 kN/m²
If the load has already been calculated for the roof, you can enter the load completely under the user-defined loads. This is shown in Figure 01 and in the video.
AnswerDIN EN 1991‑1‑3/NA, Figure NA.1A, shows the snow load zone map of Germany. The exact assignment of snow loads of administrative units, particularly at the edges of the zones, has to be checked with the competent authorities. The German Institute of Civil Engineering (Deutsches Institut für Bautechnik, DIBt) provides a table of assignment of snow load zones according to administrative boundaries for each federal state ("Zuordnung der Schneelastzonen nach Verwaltungsgrenzen") on the website https://www.dibt.de/en_US/service/notices, under Technical Building Rules.For the locations of Snow Load Zone 1 and Snow Load Zone 2 in the North German Plain, it is also necessary to check whether they are within the defined regions in compliance with DIN EN 1991‑1‑3/NA, Section 4.3. For these locations, the table of the assignment of snow load zones according to administrative boundaries ("Zuordnung der Schneelastzonen nach Verwaltungsgrenzen") shows the footnote "Nordd. Tiefld".
According to DIN EN 1991‑1‑3 and DIN EN 1991‑1‑3/NA, higher values than the ones specified in DIN EN 1991‑1‑3 and DIN EN 1991‑1‑3/NA may result for certain layers of Snow Load Zone 3. These locations are displayed in the table of the assignment of snow load zones according to administrative boundaries ("Zuordnung der Schneelastzonen nach Verwaltungsgrenzen").
Furthermore, it is necessary to consider the results of the research project "Spatial analysis of measured snow load data in five districts and their comparison to snow load zone data of DIN 1055-5: 2005 as a pilot study for the revision of the snow load zone map" by the German Meteorological Service (Deutsches Wetterdienst, DWD).
These special rules are also included in the online service by Dlubal Software. The snow load zones with special rules are indicated by an asterisk. The special rule is also displayed as a comment under the snow load zone. Figure 01 shows Snow Load Zone 3* for the city of Altenau. For Altenau, it is necessary to consider an increased snow load. This is also shown as a comment.
AnswerIf the general National Annex of EN 1991‑1‑3 is selected, the program allows you to enter any value.
AnswerIn addition to the manual operation, the website provides a web service (API) for the connection to external programs.The following packages are available for this. The same conditions apply as for manual operation.
- Geo-Zone Tool | 500 queries
- Geo-Zone Tool | 5000 queries
AnswerThe Dlubal online service geo-zone tool for load determination contains zone maps for a quick determination of snow load zones, wind load zones and earthquake zones.
The following packages are available.
- Geo-Zone Tool | 500 Requests
- Geo-Zone Tool | 5000 Requests
This contingent can be used by all employees of your company without any restrictions for all supported maps or load standards.
The Geo-Zone Tool for load determination is continuously extended and supplemented.
Drifted snow loads can be generated according to EN 1991‑1‑3, 5.3.4 (3) with the load generator. In addition to the load cases for non-drifted snow, it is also possible to quickly define load cases for the drifted snow.
For this, it is necessary to create a separately generated load for each section of the roof. Furthermore, the sides on which a drift occurs must be selected in the load generator (see the video).
AnswerThe reference height can be defined in the factors for the standard SIA 260. These can be found in General Data (see Figure 01). The desired reference height is available in the "Combination Coefficients" tab.
AnswerThe following National Annexes can be used for the load generator for snow loads according to EN 1991-1-3:CEN European UnionBDS BulgariaBS United KingdomCSN Czech RepublicCYS CyprusDIN GermanyDK DenmarkIS IrelandLST LithuaniaLU LuxembourgNBU BelgiumNEN NetherlandsNF Lyon, FranceNP PortugalNS Oslo, NorwayÖNORM AustriaPN PolandSFS FinlandSIST SloveniaSR RomaniaSS SwedenSTN SlovakiaTKP BelarusUNE SpainUNI ItalyFurthermore, the snow loads can also be generated according to DIN 1055-5, CTE DB-SE-AE and ASCE/SEI 7-16.
The load generators create a rectangular building shape. The following roof shapes are available for the roof geometry:
- Flat roof
- Monopitch roof
- Duopitch roof
In the case of different building or roof shapes, you can apply the loads manually using the tool "Generate Loads → From Area Load on Members via Plane." The load value must be determined manually.
It is also possible to generate the wind load for any building geometry with the new stand-alone program RWIND Simulation. This provides you with the possibilities for wind simulations.
and for generating wind loads. In conjunction with the structural FEA software RFEM or the structural frame analysis software RSTAB.
The direct import of models from RFEM or RSTAB allows you to define the relevant parameters for the analyzed wind directions with the height-dependent wind profiles, based on the wind standard. This results in the corresponding load cases with globally defined parameters.
You can also run RWIND Simulation manually without RFEM or RSTAB. Furthermore, it is possible to import the data from STL vector graphics.
The import of terrain and buildings of the environment into the simulation is also possible from STL files.
By exchanging the data between RFEM or RSTAB and RWIND Simulation, you can easily use the wind analysis results as load cases in the usual RFEM or RSTAB work environment.
Features of RWIND Simulation
3D incompressible wind flow analysis with OpenFoam solvers
Direct model import of RFEM or RSTAB or STL files
Simple model changes using drag & drop and graphical adjustment assistance
Automatic corrections of the model topology with shrink wrap networks
Option to add objects from the environment (buildings, terrain, ...)
Height-dependent velocity profiles according to the standard
K-epsilon and K-omega turbulence models
Automatic mesh generating adjusted to the selected depth of detail
Parallel calculation with optimal utilization of the capacity of multicore computers
Results in just minutes for low-resolution simulations (up to 1 million cells)
Results within a few hours for simulations with medium/high resolution (1‑10 million cells)
Graphically display of results on the Clipper/Slicer planes (scalar and vector fields)
Graphical display of streamlines and streamline animation
The basis for calculating a snow load is a snow load zone where the structure is located. To determine the snow load zone as well as the characteristic value of the snow load, the best way is to use our online service of Geo-zone tool for load determination. You can find it on the Dlubal Software website:
In addition to the snow load zone, this tool can also determine a wind zone as well as an earthquake zone for any location. In addition to the load maps of Germany, the Dlubal Software web application provides many other countries or standards to select.
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If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.
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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