
September 20, 2010
Use RISA to Consider Bi-Directional (Quartering) Wind Loading
RISA-3D automatically considers the complex wind combinations required by ASCE 7 using the wind load generator and the load combination generator.
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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RISA-3D automatically considers the complex wind combinations required by ASCE 7 using the wind load generator and the load combination generator.
When you model your building in RISAFloor, make sure that you define your slab edge as flexible. That will ensure that the entire contents of the diaphragm will use flexible behavior.
When dealing with a sloping site, it is often necessary to step-down the bases of columns and walls along the length of a building. The example below illustrates how to model this in RISAFloor.
RISAFloor is capable of automatically generating the wind loads on sloped roofs. Let’s look at an example of this with the model below:
The Dyn Load represents the additional load that must be included in the calculation of the total seismic weight.
RISAFloor has the capability to design wood I-Joists based on tables provided by the manufacturer, or provided by you. When modeling beams in RISAFloor, choose the Wood Product material, and choose a joist manufacturer from the shape group.
RISAFoundation now has the ability to automatically generate a circular slab with just a few easy clicks. Using the generator the program will create the mat slab and tank loading all in one easy step. Go to the Insert menu and select "Circular Foundation".
In standalone RISA-3D models (those not integrated from RISAFloor), Semi-Rigid diaphragms cannot be directly defined. Only the Rigid diaphragm type is available by default. To create a semi-rigid diaphragm in a standalone RISA-3D model, users must define plate elements manually. If you’re dealing...
In order to understand the interaction between plates and members it is important that you know the basics of Physical Members and Plate Connectivity. Remember that plates only connect to other elements at their corners, and you will instantly recognize why the model below will not work as intended.
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