August 30, 2019
Vibration Analysis for Steel Joists
RISAFloor v14 includes Steel Joist Vibration Analysis per SJI Technical Digest #5. For more information, check out the video below.
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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RISAFloor v14 includes Steel Joist Vibration Analysis per SJI Technical Digest #5. For more information, check out the video below.
RISAFoundation has the ability to create a single layer of reinforcement anywhere in a slab. This improvement allows for a more straightforward design of thin, lightly loaded slab-on-grade where two layers of reinforcement (top/bottom) would be unnecessary. In order to add a single layer of...
RISAFoundation includes the ability to utilize “nested” load combinations. Currently, the Load Combinations spreadsheet in RISAFoundation is limited to ten columns of Basic Load Cases (BLCs) and Factor combinations. However, there are times where you may need to include additional entries to your...
Strength Design (LRFD) according to the AWC-NDS 2015/2018 code has been implemented into RISAFloor v14.0. To select this code for your design, simply choose this code from the Codes tab within Global Model Settings.
RISAFloor v14 now includes floor vibration calculations per the 2nd Edition of AISC Design Guide #11. To select this code for your design, simply choose AISC DG 11 2nd Edition in the Beam Vibrations drop-down from the Codes tab within Global Model Settings.
The new release of RISA-3D is right around the corner! Check out our teaser videos to enjoy a sneak peek at some of the most exciting new features!
Last week, RISA employees spend two days volunteering at the Second Harvest Food Bank of Orange County, CA. Both days were spent at the Food Distribution Center, where staff and volunteers worked together to sort, package and distribute enough food to feed 250,000 men, women and children each...
Tension or Compression (T/C) Only members are commonly used in steel buildings when modeling braced frames that resist lateral load.
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