Common tasks for sway and drift checks

Tekla Structural Designer
2021
Tekla Structural Designer

Common tasks for sway and drift checks

Automatically merge short stacks

Columns are divided into stacks and walls are divided into panels at floor levels where members or slabs connect to the column/wall. For the purposes of sway/drift, wind drift and seismic drift checks only, you can override the default stack/panel divisions by merging a stack/panel with a lower stack/panel. The length of the combined stack/panel is then used in the checks.

A setting is provided in Design Settings to automatically do this when stacks are less than a given length.
  • With the setting off, the check considers all stacks of all columns/walls apart from those that have been manually excluded.
  • With the setting on, any stacks that are less than the limit specified are merged with the stack below, and the check is performed on the merged stack length. The check is not performed on single stack columns/walls that are less than this limit .

To turn the setting on:

  1. On the Design ribbon, click Settings.
  2. On the left hand side of the Design Settings dialog, click:
    • Drift Checks (if working to the ACI/AISC head code)

    • Sway & Drift Checks (if working to any other head code)

  3. Select Merge short stacks.
  4. Enter the minimum stack length, (below which the stack will be merged with the next adjacent stack).
  5. Click OK

Set the wind drift limit

  1. On the Design ribbon, click Settings.
  2. On the left hand side of the Design Settings dialog, click:
    • Drift Checks (if working to the ACI/AISC head code)

    • Sway & Drift Checks (if working to any other head code)

  3. Enter the Wind Drift Limit required.
  4. Click OK
The limit is applied to all columns and walls, but can be overridden if required for specific members via in the member properties.

Choose resultant or directional wind drift checks

  1. On the Design ribbon, click Settings.
  2. On the left hand side of the Design Settings dialog, click:
    • Drift Checks (if working to the ACI/AISC head code)

    • Sway & Drift Checks (if working to any other head code)

  3. Select or unselect Check for Resultant Wind Drift.
    • Selected - the wind drift limit is checked against the resultant wind drift
    • Unselected - two checks are performed, one each for Building Directions 1 & 2.
  4. Click OK

Consider wind cases only for the wind drift check

A Check wind cases only design setting (default on) is provided which applies to the check as follows:

  • With the setting on, the Wind Drift check only considers the effects of the wind loadcase(s) in wind combinations.
  • With the setting off, the check considers the effects of all loadcases in wind combinations (which would include drift induced by gravity loads).
  1. On the Design ribbon, click Settings.
  2. On the left hand side of the Design Settings dialog, click:
    • Drift Checks (if working to the ACI/AISC head code)

    • Sway & Drift Checks (if working to any other head code)

  3. Select or unselect Check wind cases only as required.
  4. Click OK

Switch off sway checks for selected columns/walls

Selected column stacks or wall panels can be excluded from the sway check as follows:

  1. Select the desired column(s) or wall(s).

    The column or wall properties are displayed in the Properties window.

  2. Expand the appropriate Sway & Drift Checks heading:
    • under All stacks, All Panels - to exclude the entire column/wall
    • under the required Stack or Panel - to exclude a specific stack/panel
  3. Unselect Sway/Seismic drift checks

Switch off drift checks for selected columns/walls

Selected column stacks or wall panels can be excluded from the drift check as follows:

  1. Select the desired column(s) or wall(s).

    The column or wall properties are displayed in the Properties window.

  2. Expand the appropriate Drift Checks heading:
    • under All stacks, All Panels - to exclude the entire column/wall
    • under the required Stack or Panel - to exclude a specific stack/panel
  3. Unselect Drift/Seismic drift checks and consider for seismic torsion

Switch off seismic drift checks for selected columns/walls

Selected column stacks or wall panels can be excluded from the seismic drift check as follows:

  1. Select the desired column(s) or wall(s).

    The column or wall properties are displayed in the Properties window.

  2. Expand the appropriate Sway & Drift Checks* heading:
    • under All stacks, All Panels - to exclude the entire column/wall
    • under the required Stack or Panel - to exclude a specific stack/panel
  3. Unselect:
    • Drift/Seismic drift checks and consider for seismic torsion (if working to the ACI/AISC head code)
    • Sway/Seismic drift checks (if working to any other head code)
    Note: *If working to the ACI/AISC head code this heading is shortened to Drift Checks

Switch off wind drift checks for selected columns/walls

Selected column stacks or wall panels can be excluded from the wind drift check as follows:

  1. Select the desired column(s) or wall(s).

    The column or wall properties are displayed in the Properties window.

  2. Expand the appropriate Sway & Drift Checks* heading:
    • under All stacks, All Panels - to exclude the entire column/wall
    • under the required Stack or Panel - to exclude a specific stack/panel
  3. Unselect Wind drift check
    Note: *If working to the ACI/AISC head code this heading is shortened to Drift Checks

Switch off tabular results for an entire level

The sway/drift, seismic drift and wind drift check results for all column stacks and wall panels at a specific level can be excluded from the tabular review data as follows:

  1. Go to the Project Workspace.
  2. In the Structure tree, expand Levels then select the level at which you want the tabular results to be switched off.
  3. In the Properties window, unselect the Check for drift option.

Override the wind drift limit for selected columns/walls

The wind drift limit specified in Design Settings can be overridden for selected column stacks or wall panels as follows;

  1. Select the desired column(s) or wall(s).

    The column or wall properties are displayed in the Properties window.

  2. Expand the appropriate Sway & Drift Checks* heading:
    • under All stacks, All Panels - to override the entire column/wall
    • under the required Stack or Panel - to override a specific stack/panel
  3. Select Override Wind Drift Limit
  4. Enter the required Wind drift ratio limit.
    Note: *If working to the ACI/AISC head code this heading is shortened to Drift Checks

Adjust column stack or wall panel check lengths

Columns are divided into stacks and walls are divided into panels at floor levels where members or slabs connect to the column/wall. For the purposes of sway/drift, wind drift and seismic drift checks only you can override the default stack/panel divisions by merging a stack/panel with a lower stack/panel. The length of the combined stack/panel is then used in the checks.

To do this manually proceed as follows:

  1. Select the desired column(s) or wall(s).

    The column or wall properties are displayed in the Properties window.

  2. Under the required Stack or Panel group, unselect the following setting:
    • Drift Checks > Merge with stack below (if working to the ACI/AISC head code)

    • Sway & Drift Checks > Merge with stack below (if working to any other head code)

Considerations for non-linear models with Tension Only bracing

For non-linear models with Tension Only bracing it is essential that the 'X Brace' pattern is used to input the braces as brace pairs rather than creating them individually. For linear analysis one of the braces in a brace pair is automatically inactivated, ensuring that the model's lateral stiffness, and hence lateral drift, is reasonably correct. If braces are input individually this will not be the case.

Perform checks

The checks are performed either by running Analyze All (Static) from the Analyze ribbon, or by running any of the Design (Static) commands from the Design ribbon.

Review tabular results in a Data Table

Tabular results can either be reported in summary, or in detail.

  • Summary - the column/wall with most critical result from all combinations is reported for each direction at each level
  • Detailed - the critical result in each direction at each level is reported for all columns/walls

The results can also be filtered by material type, characteristic and fabrication as required.

To access the tabular results from the Project Workspace Status Tree proceed as follows:

  1. Expand the Design branch of the Project Workspace Status Tree.
  2. Right-click on the required check.
  3. Select Review Data Table
For further information, see:

Create a report

Each of the results tables can be included in printed output by adding the Drift, Sway, Seismic Drift and Wind Drift chapters from the Analysis branch into your model report.

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