March 26, 2021

Video: Design Buckling Restrained Braced Frames in RISA-3D

The ability to design buckling restrained braced frames has been added to RISA-3D when you integrate your model from RISAFloor. In collaboration with CoreBrace, this new feature came as part of the release of RISA-3D v19.0.0 and RISAFloor v15.0.0.

Tags: Seismic, RISA-3D, New, BRBF

March 26, 2021 | Seismic, RISA-3D, New

Capacity Limited Design in RISA-3D

With the release of RISA-3D v19.0.2, you can now design special concentrically braced frames (SCBF) as well as buckling restrained braced frames (BRBF) according to the capacity-limited design. The objective of capacity-limited design is to ensure columns and beams in braced frames are designed to resist the capacity-limited seismic load effect based on brace expected strengths. The steps below illustrate the workflow for SCBF capacity-limited design in RISA-3D. For more information regarding design of BRBF in RISAFloor and RISA-3D, please refer to the following article: Available codes for the capacity-limited design of members include: AISC 360-10 (AISC 341-10) AISC 360-16 (AISC 341-16) If AISC 341-10 is selected, the members will be designed for the lesser of the capacity-limited and overstrength load combinations. If AISC 341-16 is selected, the envelope load combination will be used for design. Whether you’re integrating your model from RISAFloor or if you’re creating your model natively in RISA-3D, you will need to be sure to assign the proper seismic design rules to your members for capacity-limited load combinations to be considered. You can define your seismic design rules in the Seismic Design Rules spreadsheet, and assign the defined rules to members within the Properties Panel under…

November 16, 2016 | RISA-3D, New

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. 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”): 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. 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…

April 18, 2023 | RISA-3D, RISAFloor

Why can’t I see my coreBrace BRB Database?

Why is the Buckling-Restrained Brace(BRB) not showing in your database dropdown selection? Is your model in RISA-3D only? Did you detach your RISAFloor model from RISA-3D? Yes? Once your model is detached or independent from RISAFloor, your model is no longer a building only model. Thus your RISA-3D model loses available definitions such as flexible and semi-rigid diaphragms and the coreBrace database. RISA limits the Core Brace to RISAFloor integrated with RISA-3D models only. This is to ensure that this database is only used in a building model. Building models coming from RISAFloor require a few things; including uniform DL and LL, diaphragms, framing rules, among other things. RISA-3D models are not limited to any shape or geometry. Users can draw anything; bridges, roller-coasters, really anything is allowed in RISA-3D. However when using braces with tested and proprietary capabilities, the braces must be used in very specific situational conditions only. If RISA allowed these braces to be used in any RISA-3D model, it might give users results that are not valid. RISA-3D does not have the ability to alert users when the coreBrace database has been applied "wrong". This user applied error is also an issue for the capacity-limit design…