Low Rise Buildings - Geometry (ASCE 7 Wind Wizard)

Tekla Structural Designer
2021
Tekla Structural Designer

Low Rise Buildings - Geometry (ASCE 7 Wind Wizard)

The following geometry items are required for the Low Rise Buildings method. You can override calculated dimensions using your engineering judgement.

Property/Buttons Description
Property
Ground level If for some reason, the level 0.0 feet in the Tekla Structural Designer model does not correspond to the ground level, e.g. you have used a site datum rather than a building datum, then this field allows you to set the appropriate value so that the reference heights for the wind can be calculated correctly. The default is zero. The allowed maximum is the minimum wall or roof height. Changing the value in this field will cause the Mean Roof Height to be recalculated, unless you have chosen to override that dimension.
Orientation of Longitudinal Direction relative to axes (Figure 28.4-1)

This information is required to control the orientation of the Transverse and Longitudinal directions, and thus the Tekla Structural Designer Wind Directions. For simple roof shapes, ASCE 7- 10 Wind Wizard will calculate a default value as below.

  • Single flat roof - orient along longest side,

  • 2 Duopitch roofs - orient along common edge,

  • 2 Hip Main roofs - orient along common edge.

  • Changing the value in this field will cause either or both of the Longitudinal and Transverse Dimensions to be recalculated, unless you have chosen to override them.

Roof Angle

The field is always visible, even if there are no roof panels in your model. It is calculated as follows:

  • No roof panels - θ = 0°.

  • Else - use maximum angle for all roof panels in the model.

You are able to override the calculated value by checking the box; The limits are 0° to 80°.

Mean Roof Height, h (Clause 26.2)

The field is calculated as follows:

  • No roof panels -h is maximum reference height for walls,

  • Else if θ <=10° - use maximum eaves height, (h e), for all roof panels in the model, (see Figure 28.4-1)

  • Else - use maximum Mean Roof height, (h), for all roof panels in the model.

In the example below, h = (hu + hl)/2 - g

h is limited to a maximum of 60 ft or the Least Horizontal Dimension, whichever is lower. You are able to override the calculated value by checking the box.

Longitudinal and Transverse Dimensions (Clause 26.3 and Figure 28.4-1)

These are similar to the Overall building X dimension and overall building Y dimension (Clause 26.3) for the Rigid Buildings of All Heights Method.

These dimensions are calculated from the smallest enclosing rectangle (considered over all roof and walls only), relative to the given orientation of the Longitudinal Direction. You are able to override each calculated value by checking its box. These values will then be used to derive the L and B dimensions for each wind direction.

For Longitudinal Wind Directions, L = Longitudinal Dimension, B = Transverse Dimension.

For Transverse directions, L = Transverse Dimension, B = Longitudinal Dimension.

Buttons
Next Clicking Next takes you to the Basic wind data page.
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