October 15, 2012
Updated Torsional Shape Properties
RISASection v2 includes updated torsional shape properties for a more accurate analysis. Check out the video below for more information:
Welcome to a high-level walkthrough of dynamic analysis in RISA-3D! This guide introduces essential aspects of modeling dynamics, focusing on natural frequencies, mode shapes, and the impact of dynamic behavior on structural integrity. The Dynamics Scenario Imagine we’re tasked with evaluating the stability of a cantilevered pedestrian bridge that spans over a city street. The bridge is connected to a building on one side and features decorative panels and a lightweight canopy. The concern? Wind gusts and foot traffic could cause the bridge to vibrate. Our goal is to understand its dynamic properties—natural frequencies and mode shapes—and assess whether it can handle these dynamic forces without compromising structural stability. We start by setting up dynamic mass for each load case: Canopy Load: Applied uniformly along the length of the bridge to account for wind effects. Pedestrian Load: Simulated at intervals along the span to reflect walking traffic. Decorative Panels: Modeled with specific weights on each side. Once mass and stiffness are set, RISA-3D enables us to simulate how the structure behaves dynamically, revealing which parts might be sensitive to specific frequencies or forces. Running the Eigensolution Analysis In RISA-3D, we use an eigensolution to identify: Natural Frequencies (intrinsic vibration rates…
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RISASection v2 includes updated torsional shape properties for a more accurate analysis. Check out the video below for more information:
The Steel Joist Institute (SJI) has recently put together a Virtual Joist Girder table which converts common joist sizes into equivalent wide flange beams. This topic describes how to use these Virtual Joist Girders within the RISAFloor program.
The Steel Joist Institute (SJI) has developed a Virtual Joist Girder table which converts common joist sizes into equivalent wide flange beams for use in RISA-3D.
Let’s consider the example of the frame shown below. Suppose there is a diaphragm present at the framing level, and that the wall shown is intended only to handle the lateral loads. In reality the columns will be in-line with the wall, and the cantilever beams will pass over the wall without...
RISA programs are Windows based and have historically been installed only on PC’s. Although RISA programs do not run natively on an Apple computer we have done some testing to confirm that our programs will run on a Mac using a virtual computer running a Microsoft Windows OS.
RISAFoundation includes a footing element which is represented by a single node. A frequent question that arises is how to apply multiple point loads to a single footing, but at different locations. This can be done with or without corresponding pedestals, but for the example below multiple...
While RISA-3D does not currently have pilaster design, there are still plenty of situations where you would want to have a column embedded within a wall. The idea behind this is that the column handles the gravity loads for any beams which frame into it, while the wall handles lateral loads. No...
RISAFloor has some default decks provided for you when you open the program in the Deck Definitions spreadsheet. You can use one of these decks or you can create your own by going to the bottom of the spreadsheet and press ENTER.
RISA-3D v10 now has the ability to quickly and easily apply hydrostatic loads to circular tanks using the Cylinder Generator. This generator can be found by clicking the Templates button and choosing the Cylinder - Plates/Members option.
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