Wind load definition

Vertical vessels on supports such as skirts and legs can be affected by the wind and can transfer substantial loads to the base. In NextGen it is possible to calculate the wind profile automatically using the following standards:

• Eurocode 1 EN 1991-1-4

• Uniform Building Code (UBC 97)

• ASCE/SEI, IBC

• IS 875 (Part 3)

• NTC

It is also possible to manually enter a wind profile, for those cases where the calculation is to be performed with a standard not supported by NextGen.

Filling in the wind and earthquake data only influences the calculation if supports are present. Pressure components are generally not influenced by external loads, except in some specific cases.

Definition using a known Standard

Inside the Item properties Item > Properties, in the Wind section there is a list from which to choose the Code according to which you want NextGen to calculate the load due to the wind.

In the example, a wind calculation according to Eurocode 1 has been set and with a basic wind speed of 15 m/s.

Refer to the contextual help for more information on each of the input data

Click on Update to save the changes. Then, moving on to the profile view in Item > Wind, you can see that the program has set the wind thrust at different altitudes as established by the standard, limiting itself to the height reached by the equipment.

If the vessel is placed at an offset from the ground, this distance can be set in the properties of the Item, in particular in Item > Properties > Geometry > Distance from reference line

Manual definition of the wind profile

In the window relating to the properties of the Item seen previously, the profile called Custom must be chosen.

Then, by choosing Item > Wind it is possible to define a series of manual points for the graph, indicating a series of elevation-pressure pairs.

Load combinations

The stress due to the wind is used by the calculation of the supports, through the scenarios defined as Load Combinations in Item > Load Combinations.

For each Load Combination it is possible to consider or not the wind and define a coefficient.

Resistant profile

NextGen automatically calculates the wind resistant profile. As usual, it is possible to intervene on this calculation by acting on the components, in their External loads category.

You can customize both the surface exposed to the wind and the shape coefficient.

Report

In the initial summary pages of the calculation report, if set to active, there is the section containing the wind calculation:

The support calculation, for the Load Combinations in which the wind is present, will show the relative load: