November 16, 2016


How the Analysis Offset feature can be used to design WT Braces


In the RISA-3D when you model a WT brace it exists at the member centroid, which means that no bending ends up in the brace due to the fact that the brace is actually eccentric to the braced frame.

WT1

In Version 15.0 we added a feature called “Analysis Offset” which moves the centroid of the member for analysis. In the example below the flange of the WT is bolted to a gusset that is ¾” thick, so we would want the centroid to be moved to the face of the flange, plus half the gusset thickness (3/8”):

WT2

With this offset applied, when the model is solved you’ll note that the brace bows out of plane, indicating that it does have bending.

WT3

The detail report confirms this. Note how much the Code Check value increases when the real-life bending due to eccentricity is considered in the RISA model.

WT4

Tags: RISA-3D

You may also be interested in

Nov 8, 2018 | Tips & Tricks
Mat Slab Overturning and Sliding Safety Factors

RISAFoundation v11.0 includes two new tabs in the Safety Factors resul...
Read More

Aug 21, 2019 | Tips & Tricks
RISA-3D v18 Sneak Peek Videos

The new release of RISA-3D is right around the corner! Check out our t...
Read More

Jul 12, 2019 | Tips & Tricks
Implementing Realistic Behavior for T/C Members in RISA-3D

Tension or Compression (T/C) Only members are commonly used in steel b...
Read More

Jun 20, 2019 | Tips & Tricks
Understanding Wall Panel Forces with Rigid Diaphragms

Rigid diaphragms represent a plane of very high rigidity and distribut...
Read More