Effective Length Calculator dialog

Used to calculate the effective length coefficients and lengths (KY, KZ, LY, and LZ parameters) for steel frame members for design.

Opens when the Effective Length button is clicked on the Steel Design - Whole Structure dialog.

Tip: One or more steel design parameter blocks must be defined in the model before the Effective Length Calculator tool can be used.

Note: If you want to re-calculate the effective length parameters for a parameter block, you must first remove the existing parameters from the parameter block. This is true whether the existing parameters were manually entered or if the tool was previously used. The effective length calculator tool does not overwrite any existing values. It will only add new values to the end of the parameter block.

Setting	Description
Parameter Block	Select the steel design parameter block which this effective length calculation will apply.
Method (Code)	The AISC nomograph method described in AISC 360 is used.
Braced	Select the local axes which are restrained against buckling.
Unbraced Length	Select how the unbraced length should be determined: Length of analytical member - the length of the analytical member is assumed as the unbraced length Calculate Automatically - the program will calculate the unbraced length based on the model, taking into account connecting members and member colinearity.
Theta	Connecting members are assumed to provide lateral restrained against buckling when the connect to the member. However, members which connect at a shallow angle may not provide sufficient restraint. The angle, θ (theta), is the angle away from 90° to the member at which connecting members should can no longer provide sufficient restraint. Angles between 0° and 80° (inclusive) are allowed. A value of zero indicates that only normal members provide restraint.
Colinearity Tolerance	The program uses this to determine the effective lengths for adjacent, colinear analytical members. When the longitudinal axis (i.e.., local x axis) of two adjacent members differs by greater than this angle, the program will no longer assume they are the same member for automatic calculations of the effective length.
Assignment	Specify the members to which these effective lengths are assigned: Member List - the list of members which are assigned Select on Model - click to active the selection mode. Then click on members in the view window to add these to the Member List. Click this tool again to deactivate selection mode. Select Group - click to open the dialog, which is used to select members by previously defined group names. Note: You can select members before opening the dialog to have those member numbers automatically prepopulate the Member List. To view the members which will be assigned, click Highlight.