Apply loads to loadcases on completion of the snow wizard

Tekla Structural Designer
2021
Tekla Structural Designer

Apply loads to loadcases on completion of the snow wizard

On completion of the snow wizard loadcases will have been set up for four types of snow load - namely

  • balanced or undrifted snow load (even UDL)
  • unbalanced or drifted snow load (wind blown leeward and windward UDLs)
  • valley drifted snow (wind blown VDLs on the two adjacent slopes in a valley)
  • local drifted snow (VDL on UDL - snow load blown against a parapet, eaves step or object)

If working to the US or EC head code - loads in the unbalanced or drifted snow loadcases have to be applied manually as uniform snow, valley snow, or local drift snow loads.

If working to the AS, BS, or IS head code - loads in all snow loadcases have to be applied manually as uniform snow, valley snow, or local drift snow loads.

Note: Any snow loads that are not appropriate for the selected loadcase cannot be selected.

Apply uniform snow loads

  1. In the Loading list, select a snow loadcase generated by the wizard appropriate for uniform snow.
  2. On the Load tab, click Snow Load > Uniform Snow.
  3. In the Properties window, adjust the load details according to your needs.
  4. To apply the load, click the relevant roof panel.
    Note: In the unbalanced or drifted cases, setting Roof type option to Pitched allows you to select whether the wind type of the load should be Windward or Leeward.

Apply a valley snow load

  1. In the Loading list, select a snow loadcase generated by the wizard appropriate for valley snow.
  2. On the Load tab, click Snow Load > Valley Snow.
  3. Select the left roof panel of the valley in which the load is applied.

    Tekla Structural Designer automatically determines the right panel, and calculates the valley load.

    Tip: If necessary, you can use apply a user override to the calculated load. Even if you rerun the Snow Wizard, Tekla Structural Designer maintains any user overrides that you have applied.
    Note: Graphic displays depict the loading magnitude of a snow load, and not depth of loading. Remember this when reviewing the load that has been calculated on structures like the low pitched valley model shown below:

    Although the above image appears to indicate snow load rising above the ridges, the display actually views the loading magnitude.

Apply a local drift snow load

  1. In the Loading list, select a snow loadcase generated by the wizard appropriate for local drift snow.
  2. On the Load tab, click Snow Load > Local Drift Snow.
  3. Go to the Properties window.
  4. Specify the drift type, and then enter the height, and any other parameters required to define the drift.
  5. In the model, select the roof panel edge where the drift is to form, taking care to click close to the required edge.
    Tip: The edge closest to the cursor is highlighted, if this isn't where you want the drift to form move the cursor toward the edge required before clicking to select.
  6. Click the start point of the drift on the highlighted edge.
  7. Click the end point of the drift on the highlighted edge.
    Tip: If necessary, you can use apply a user override to the calculated load. Even if you rerun the Snow Wizard, Tekla Structural Designer maintains any user overrides that you have applied.
  8. If you have another drift load to apply to the same panel in the same loadcase, repeat the above steps starting from step 3.
    Note: If working to the US head code, when applying the second and subsequent drift loads to the same roof panel, a Do not apply balanced load setting is automatically enabled in the load properties. (This setting was disabled for the first drift load to ensure the balanced load gets applied.) The second and subsequent drift loads use the balanced load of the first drift to determine their drift load and extent. Working in this way, it is not necessary to override the load value in order to apply the second and subsequent drift loads.

Override snow loads

You can apply user overrides for snow load values and drift lengths, if necessary.

  1. Select the snow load.
  2. In the Properties window, select the Override load value option.
  3. Specify the override value.

    Tekla Structural Designer maintains the user overrides, even if you rerun the Snow Wizard.

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