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EN 1991 Snow Load Calculation

Using the SkyCiv Load Generator in EN 1991-1-3 Snow Load Calculations

To calculate the snow 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, only users with a Professional Account or who purchased the standalone Load Generator module will be able to use this calculation. You can purchase the standalone module thru this link.

Site Data

Using EN 1991-1-3, you need to an address in the Project Address input first and the software will automatically get the snow load for that location. Currently, the load generator supports the following countries:

  • Belgium
  • France
  • Germany
  • Ireland
  • Luxembourg
  • The Netherlands
  • United Kingdom

The snow load values were obtained using Appendix C of EN 1991-1-3 or each individual National Annex. To display the snow region map, you need to click “View Map Contours” and then select “Snow.”

Figure 1. Site tab of SkyCiv Load Generator

Structure Data

The structure data and the wind and snow parameters are separated into different accordions. In order to calculate snow loads, the snow load checkbox should be checked.

Figure 2. Snow load parameters on SkyCiv Load Generator

Topography for EN 1991-1-3 Snow Calculation

This parameter is used in getting Exposure Coefficient Ce. The definition of each option is defined in table below:

TopographyDefinition
WindsweptFlat unobstructed areas exposed on all sides without, or little shelter afforded by terrain, higher construction works or trees.
NormalAreas where there is no significant removal of snow by wind on construction work, because of terrain, other construction works or trees.
ShelteredAreas in which the construction work being considered is considerably lower than the surrounding terrain or surrounded by high trees and/or surrounded by higher construction works.

Type of Snow

This parameter is used in getting the mean bulk weight density of snow, γ. The definition of each option is defined in table below:

Type of SnowBulk weight density kN/m3
Fresh1.0
Settled (several hours or days after its fall)2.0
Old (several weeks or months after its fall)3.0
Wet4.0

Design Situation

Currently, Design Situtation is limited to Normal Condition.

Consider Unbalanced/Drifted Snow Load Case?

This parameter is a “Yes” or “No” to calculate for Unbalanced Snow Load Case. Upon selecting “No,” the balanced snow load case shall only be calculated. On the other hand, upon selecting “Yes,” the unbalanced snow load case table will show.

Drift on duopitch roof

This case is used to calculate the drifted snow load on duopitch/gable roof as shown below:

Figure 3. Parameters for calculating drifted snow load on duopitch/gable roof.

Drift on monopitch roof

This case is used to calculate the drifted snow load on monopitch/monoslope roof as shown below:

Figure 4. Parameters for calculating drifted snow load on monopitch/monoslope roof.

Drift on projections and obstruction

This case is used to calculate the snow load drift on obstructions above the roof level such as parapet walls, firewalls, chimneys, etc.

Figure 5. Parameters for calculating drifted snow load on obstructions and projections above roof.

Drift on roof abutting to taller construction works

This case is used to calculate the snow load drift on roof abutting to taller construction works.

Figure 6. Parameters for calculating drifted snow load on roof abutting to taller construction works.

Results

The snow load results will show the parameters in calculating the undrifted snow load as shown below:

Figure 7. Snow load parameters used in calculation and the calculated undrifted snow load

Unbalanced/Drifted Snow Load

If Unbalanced/Drifted Snow Load is selected to be considered, the results are tabulated on a table depending on the cases defined:

Figure 8. Sample results for drifted snow load on duopitch and monopitch roof.
Figure 9. Sample results for drifted snow load on projections and obstructions, and abutting to taller construction works.

Detailed Calculation

The detailed snow 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.

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