
June 22, 2010
How to Create an Engineered Wood Material
In RISA-3D and RISAFloor, the entire NDS species list is available as well as glulam materials but you may need to design a wood product that is not available in the program.
Modeling instability can be one of the most frustrating errors to troubleshoot in structural software. Whether you're a new user or a seasoned pro, instability warnings in RISA-3D can bring your workflow to a halt if not properly diagnosed and resolved. This master article brings together all the most common types of instability, provides guidance on identifying the issue, and links to existing resources that walk you through the resolution process. To supplement this written guide, check out the Troubleshooting Mini Tutorial in the RISA Learning Center (RLC). Common Instability Types and How to Resolve Them Below are the five most common causes of instability in a RISA-3D model, along with diagnosis tips and links to deeper resources: 1. Member End Releases at Boundary Conditions Symptom: Instability warnings at the base of columns or ends of beams. Diagnosis: Look for members where moment releases are applied directly at nodes with pinned or fixed boundary conditions. Why It’s a Problem: This removes all rotational fixity at the connection, creating a hinge with no resistance to rotation. Resolution Resource: How do I avoid instability warnings in a RISA-3D model? 2. Pinned End Releases at Every Member Framing into a Single Node Symptom:…
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In RISA-3D and RISAFloor, the entire NDS species list is available as well as glulam materials but you may need to design a wood product that is not available in the program.
To best understand how plates interact with each other you must first understand the concept of Physical Members. The important thing to keep in mind is that plates are not physical members. A plate is defined using either three or four joints, and it only connects to other plates at those joints....
When you have a deep column, it is necessary to model the beam so that it connects to the face of the column. This results in an eccentricity at the joint. RISA-3D offers two ways to model this eccentricity.
The customizable toolbar is a new feature in RISAFloor. It’s really useful and you may have overlooked it. You’ll find all of your familiar buttons as well some new buttons which make reviewing your model and results easier.
There are four different values for Unbraced lengths in RISA-3D, RISA-2D and RISAFloor. Two are for axial calculations and two are for bending calculations.
Members (beams, columns, braces, etc.) are defined in RISA by an I-Node and a J-Node. While you and I see a beam occupying physical space between two columns, most programs see a line between Point I and Point J. This is known as a non-physical member. See the image below:
If you have ever tried to solve a two-dimensional model in RISA-3D, you have ultimately run into instabilities in your model because your model has no out of plane restraint.
Do you get an instabilities warning when you’re trying to do a simple 2D model in RISA-3D?
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