Wind loads on axisymmetric structures

The option generates wind loads on axisymmetric structures (structures whose base is a regular polygon). The option is available for the following codes:

• American snow/wind code ANSI/ASCE 7-98
• French snow/wind code NV65 (article 3) or NV65 02/09

The following image (for the French snow/wind code) shows structure types for which wind loads can be generated.

The option generates wind loads on selected planar finite elements and on panels. Prior to using this option, you should select panels or finite elements on which the wind loads will be generated.

You can start generating snow/wind loads using either method:

• Click Loads menu > Special Loads > Wind on cylinders.
• Click .

At the top of the dialog in the Wind directions field:

• Generating list - You can specify a direction along the height of the axisymmetric structure (cylinder). You can select directions X, Y, and Z of the global coordinate system.
• Wind lets you define the directions of the generated wind loads. Directions refer to the global coordinate system.

The following parameters can be defined at the bottom of the dialog in the Structure type field.

• For the French code:

  Category - The list of available categories of the calculated structure:

  category I	Prism: 3 or 4 faces
  category II	Prism: 5 to 10 faces without curved ribs
  category III	Prism: 11 to 20 faces with/without curved ribs
  category IV	Cylinder: round base with thin or thick ribs (sharp edges)
  category V	Prism: more than 20 faces with/without curved ribs
  category VI	Smooth cylinder with round base without ribs (glossy)

  If category II is selected, the Number of faces option becomes available. You should select the number of axisymmetric structure faces from the list. For the remaining categories, the Number of faces option is unavailable.

• For the American code:

  Category - the list contains available categories of the calculated structure:

  category I	Square
  category II	Hexagonal or octagonal
  category III	Round moderately smooth
  category IV	Round rough (D'/D=0.02)
  category V	Round very rough (D'/D=0.08)

  For each category, the Number of faces option is also available. You choose a number of axisymmetric structure faces from the list.

Note: Because the ASCE 7-98 code does not specify how a resultant force should be distributed over the surface of a structure, the method of distribution used for the French wind load code NV 65 modifies 99 is applied to the ASCE 7-98 code in Robot.

After specifying the basic parameters for an axisymmetric structure and clicking Parameters, the definition of wind load parameters dialog opens.