In a RISAFloor model the columns and beams can be assigned unbraced lengths, or the program may calculate them automatically. This unbraced length information can then be used in RISA-3D. A great example is the frame below: The beams along Grid Lines 1 and 2 have fixed ends. Therefore their bottom flanges are in compression, […]

Aside from leaving an unbraced length blank or inputting a fixed distance, you can harness the program’s ability to use a limited intelligence for determining unbraced lengths. In order to do this you can simply type in the name of the Unbraced Length Commands into the unbraced length field. Below are the two most common commands: Segment […]

There are three types of unbraced lengths in RISA: Lb Values (Lb, Lu, Le), Lcomp Values (Lcomp, Le-bend) and L-torque.

The axial compression and flexure strength of beams and columns is dependent on the spacing of elements which provide bracing along the length of those members. You may specify unbraced lengths as a fixed distance or by using RISA’s Unbraced Length Commands. These unbraced lengths are used for member capacity calculations. However, specifying bracing via […]

In RISAFloor, the beams are susceptible to two forms of buckling; Euler buckling and lateral-torsional buckling. The unbraced length is determined in RISAFloor using the deck properties and framing.