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EN 1991 Wind Load Calculations

Using the SkyCiv Load Generator in EN 1991-1-4 Wind Load Calculations

To calculate the wind load pressures for a structure using SkyCiv Load Generator, the process is to define first the code reference. From there, the workflow is to define the parameters in Project Tab, Site Tab, and Building Tab, respectively. However, free users can only use the calculation for a gable roof for a maximum of 3 solves per day. With a Professional Account or by purchasing the standalone Load Generator module, you can use all the features of this calculation as long as you want You can purchase the standalone module thru this link.

The supported countries for EN 1991-1-4 calculation in this module are as follows:

  • Belgium
  • Czech Republic
  • Finland
  • France
  • Germany
  • Greece
  • Ireland
  • Italy
  • Luxembourg
  • The Netherlands
  • Poland
  • San Marino
  • Slovakia
  • Slovenia
  • United Kingdom

Site Data

Users can get the wind speed by location any time from the SkyCiv free wind speed map database. Using EN 1991-1-4, you just need to put the address of the structure located in any of the supported countries. The necessary parameters will show according to National Annex governing the structure location. In order to explain it further, we will use Oxford Street, Manchester, UK as the arbitrary address.

Figure 1. Site Tab.

For some locations, Season/Month dropdown will be shown to calculate the season factor, cseason. Otherwise, cseason is assumed to be equal to 1.0. Moreover, Wind Direction and Terrain Category options depend on the governing National Annex. Wind Direction parameter is used to calculate the directional factor, cdir, and should be based on the wind direction relative to True North. Hence, the value is the opposite of the wind source direction which is used in obtaining cdir. On the other hand, Terrain Category is used in calculating roughness factor, cr(z). Furthermore, specific to BS EN 1991-1-4 and IS EN 1991-1-4, Distance upwind to shoreline or inside town terrain and Displacement Height, hdist, should be defined. The Load Generator module will automatically calculate the Distance upwind to shoreline based on the wind direction selected. However, it should be modified to Distance inside town terrain if the Terrain Category selected is Town.

Figure 2. Elevation chart and other parameters.

Structure Data

The structure data and the wind and snow parameters are separated into different accordions. In order to calculate the design wind pressures, the wind load checkbox should be checked. For AS/NZS 1170, Building is the only option for Structure dropdown.

  • Building – supports the following roof profile:
    • Duopitch, Hip, Monopitch
    • Open Duopitch, Open Monoslope
Figure 3. Building dimension.

Note that for free users, only Gable roof is available for Building. Once you have completed all the structure data inputs, you can visualize the structure by clicking the 3D Render at the right side.

Figure 4. 3D render of structure.

Next step is to define the Wind Parameters depending on the structure selected based on EN 1991-1-4. You can either select calculations for Buildings or Canopy Roof. Moreover, Area of Wall Component and Area of Roof Component can be modified especially if Components/Claddings are being designed.

Results

Once all the parameters are defined, clicking the Generate Loads button will give a result as shown below:

Figure 5. Pressure results.
Figure 6. Results figure.

Detailed Calculation

The detailed wind load calculations can be accessed only by Professional account users and those who purchased the standalone load generator module. All the parameters and assumptions used in the calculation are displayed on the report to make it transparent to the user. You can download a sample detailed calculation thru this link.

Figure 7. Detailed report.

For additional resources, you can use these links for reference:

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