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Steel Purlin Design Settings

Steel Purlin Design Settings are explained in detail under this title.


  • The parameters used in the design are intervened in the Design tab. If a mark is placed in the box, the coefficient written in the box is used in the design calculation. If no mark is placed in the box, the program automatically calculates these coefficients and uses them in the design.

Laterally unbraced length ratio (LTB)

The ratio of the length between laterally unbraced length along either flange

The lateral-torsional buckling modification factor (Cb)

Lateral-torsional buckling modification factor for non-uniform moment
diagrams when both ends of the beams are supported. It is determined according to AISC 360-16 F1-1.

Deflection limit

It is the member-based limit value specified in the relevant Steel Structures regulation used in the design. The program does not automatically change the limit such as cantilever beams. The limit value must be changed by the user according to the situations where the beam is used.

  • The control is given in the steel design-tray - details section after analysis and design.

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