How do I check for Wind Drift?

Introduction

Tekla Structural Designer 2016i has added a wind drift feature to the software.

Wind drift checks are performed on both steel and concrete column stacks. A stack is defined as the length between floors.

They are only performed on wind load cases as well as to service combinations that contain wind. In any other load combination this check is not performed.
 

How do I turn Wind Drift checks On/Off?

The Wind Drift check is a property of the individual column. This provides the ability to turn the check for specific columns On/Off, if required for the whole column or individual stacks.

If the checkbox is blank (Off) then no drift check will be performed on the column

If the checkbox is checked (On) then the user can specify the Wind Drift ratio limit required for the check. The default for all Head codes (BS, EC, AISC) is 300. This can be altered to suit.

 

How is the Wind Drift check performed?

A wind drift check is performed for wind load cases and service combinations containing wind load only, for column stacks that have the wind drift check property checked (On).

Wind drift is reported in the Project Workspace > Status tree and detailed information is available in the Review view > Tabular Data tables.

 

Tabular Data table

 


Set the View Type as Wind Drift.

Set the Material Type to be Steel, Concrete or both

Set the Characteristic as Columns

 

Set the Wind load case or Service combination to review results for

 

The table is then propagated.

Deflection and Drift results in Direction 1 and Direction 2 of the columns are provided for those column where a drift check was requested.

For columns not requested, "Not required" is reported in the table.

 
 

Results View > Deflection Diagram

The table above can also be cross matched against the Results view, deflection diagram

  

Image

Select the Deflection direction of interest and overlay Deflection text on the view.

 

Results will be displayed for the selected wind load case or service combination

 

     Note. Scene Content > Members > Beams have been turned off for result clarity.

The stack height for this column is 4000mm i.e. Base - 1st floor, 1st - 2nd floor and 2nd - Eaves level

 
 

Calculation

Drift is therefore calculated for each stack for both directions. The results below are for Direction 1 to 1dp.

The drift status is calculated as "height of each floor" / "drift between top and bottom"

Thus, Drift between top and bottom of each stack

Base-1st floor 47.7-0 = 47.7mm

1st-2nd floor 68.8-47.7 = 21.1mm

2nd-Eaves 84.8-68.8 = 16.0mm



Thus, Drift status. "height of each floor" / "drift between top and bottom"

Base-1st floor 4000 / 47.7 = 83.8 < limit of 300 so FAIL

1st-2nd floor 4000 / 21.1 = 189.6 < limit of 300 so FAIL

2nd-Eaves 4000/ 16.0 = 250 < limit of 300 so FAIL