Risa Tips & Tricks: How to Use Our Structural Analysis Software

October 29, 2026

5 Frightening RISA-3D Modeling Errors That Can Haunt Your Results

Spooky season is here with ghastly ghosts, glowing jack-o’-lanterns, and wicked witches around every corner. While Halloween scares can be fun, unexpected surprises in a structural model are a different story. This spooky season, keep an eye out for a few frighteningly common modeling issues in RISA-3D. Catching these modeling concerns early can help you create models that are a treat to analyze, not a trick. 1. Locked Nodes Does it ever feel like there’s a ghost in your model? You run your analysis and discover a LOCKED reaction in the results. Don’t be scared, these reactions are not supernatural. They are created by RISA-3D when the model is not adequately supported for a specific degree of freedom. Locked nodes provide temporary restraint to help stabilize the model during analysis, but they should not be treated as the final solution. Because these added restraints do not report the load removed from the model, they can obscure the intended load path. Investigate and resolve the underlying instability so you can confirm that loads are transferring through the structure as expected. For a closer look at common sources of RISA-3D instability warnings and ways to troubleshoot LOCKED reactions, read The Ultimate Guide…

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Diaphragms (2)

September 13, 2012

How Can I Use a Wall for Shear Only (no Bearing) in RISA-3D?

Let’s consider the example of the frame shown below. Suppose there is a...

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February 13, 2012

RISA 3-D: How to Apply a Rigid Diaphragm

In RISA-3D, rigid diaphragms can be added using the Diaphragm spreadsheet....

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November 29, 2010

How to Check Frame Story Shears in RISA-3D

When using rigid diaphragm analysis in RISA-3D it can be useful to...

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September 14, 2010

How to Design Flexible Diaphragms in RISAFloor

When you model your building in RISAFloor, make sure that you define your...

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July 29, 2010

How to Model a Semi-Rigid Diaphragm in Standalone RISA-3D

In standalone RISA-3D models (those not integrated from RISAFloor),...

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