
August 27, 2020
VIDEO: Creating Custom Shapes in RISA-3D
Learn how to build custom steel and concrete shapes using RISASection and then import them into RISA-3D to incorporate them in analysis and design.
Light-framed construction has become increasingly prevalent in mid-rise and modular development, driven by its cost-efficiency, speed of construction, and adaptability. But with flexibility comes complexity. Engineers designing with wood and cold-formed steel (CFS) must navigate a unique set of challenges: diaphragm behavior, segmented shear walls, buckling sensitivity, and code-specific checks that differ from traditional hot-rolled steel or reinforced concrete structures. This article explores practical modeling and design approaches for light-framed buildings, focusing on how structural engineers can balance constructability, analysis clarity, and compliance with governing codes. Diaphragm Behavior: Not Always Rigid In light-framed buildings, flexible diaphragms are often assumed due to the nature of wood sheathing or light-gauge decking. However, as buildings increase in size and irregularity, this assumption deserves scrutiny. Flexible diaphragm assumptions work well in rectangular buildings with regular framing, but irregular load paths or large openings may require semi-rigid modeling to capture torsional behavior. Engineers should consider the influence of diaphragm stiffness when assigning lateral forces, especially in hybrid systems where part of the structure may be stiffer or tied into concrete cores. In projects where semi-rigid diaphragm analysis was warranted, integrating tools like finite element meshing helped visualize how in-plane stiffness impacted overall response—particularly in designs…
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Learn how to build custom steel and concrete shapes using RISASection and then import them into RISA-3D to incorporate them in analysis and design.
When using RISA Integration between RISASection and RISA-3D, RISA-2D and/or RISAFloor, there are a few common mistakes that people make when attempting to access the RISASection files from the Shape Database.
There are multiple options in RISA-3D and RISAFloor to create a custom shape not available in the program databases. The first, is to utilize RISASection in order to create cross-sections, calculate section properties and import the shape directly into RISA-3D. For more information on integrating...
Use RISASection to find the properties of built-up steel sections, then model beams using the same section properties in RISA-3D and get full code-checks using AISC 360. This webinar will teach you how to use RISASection quickly and easily to determine complex section properties.
RISASection v2 includes updated torsional shape properties for a more accurate analysis. Check out the video below for more information:
In order to get code calculations, RISA-3D and RISA-2D need to know what type of shape would be most similar to yours. This is because the program needs to use the correct code equations for your shape type.
RISASection 2.0 includes the ability to assign your section as one of the predefined hot rolled steel Shape Types (Wide Flange, Channel, Tube, etc.). This means that when the shape is imported into RISA-3D, you will now be able to get design results and code checks for the member.
The latest version of RISASection, includes a powerful new DXF import feature. This feature allows the user to import any 2D geometry into RISASection for the calculation of the cross-sectional properties and the import into RISA-2D, RISA-3D or RISAFloor for use in the larger model.
Modeling built-up or composite sections can easily be done in RISASection. Because the properties of such a section are computed using a weighted summation of the transformed shape properties, RISASection uses a Property Multiplier to specify the relative weight of a single shape in a built up...
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