Wind Load – EN 1991-1-4 (2010)
Eurocode 1 EN 1991-1-4 Action on structures (wind load) and EN 1991-1-4 (2010) contains detailed information and formulas for computing wind loads on buildings in various geographic locations. The procedure described in this code has been included in CAEPIPE starting Version 10.30 and can be accessed through this option Layout Window > Misc >Wind Load – EN 1991-1-4 (2010).
By defining the wind parameters in the dialog shown, CAEPIPE will compute the Design Wind Force internally as per EN 1991-1-4 (2010) and apply the same to the piping system. For details on implementation, refer to Appendix “EN 1991-1-4 (2010)” from Code Compliance Manual.
Fundamental value of the basic wind velocity can be obtained from National Annex for EN 1991-1-4.
Terrain Category
Based on the location of the structure, Terrain Category classification can be obtained from the Annex A and Table A.1 of EN 1991-1-4.
Directional and Seasonal Factors (Cdir & Cseason)
In order to calculate the Basic Wind Velocity as per Expression (4.1) of EN 1991-1-4 (2010), we need to determine the directional and seasonal factors (Cdir & Cseason). National Annex for EN 1991-1-4 simplifies this calculation as the suggested values of these factors are equal to 1.0.
Terrain Orography
The recommended value of the Terrain Orography factor is 1.0.
Where orography (e.g. hills, cliffs etc.) increases wind velocities by more than 5% the effects should be taken into account using the orography factor Co(z).
The procedure to be used for determining Co(z) may be given in the National Annex. The recommended procedure is given in A.3 of EN 1991-1-4 (2010).
The effects of orography may be neglected when the average slope of the upwind terrain is less than 3°. The upwind terrain may be considered up to a distance of 10 times the height of the isolated orographic feature.
Turbulence Factor (Kt)
Turbulence factor (Kt) may be given in the National Annex. The recommended value for Kt is 1.0.
Roughness Length and Minimum Height
Roughness Length (Zo) and the Minimum Height (Zmin) are provided for each Terrain Category in Table 4.1 of EN 1991-1-4 (2010).
Upon defining the above parameters, the user can apply Wind Load by selecting the wind code as “EN 1991-1-4 (2010)” through Layout Window > Loads > Wind 1/Wind 2/Wind 3/Wind 4.
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