RISA | Tips & Tricks

November 19, 2024

How to Run a Basic Dynamic Eigensolution in RISA-3D?

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…

October 18, 2018

Updates to Wood Wall Aspect Ratio Limits in RISA-3D

With the initial implementation of wood wall design in RISA-3D, the wall aspect ratio was calculated as the full height of the wall divided by the width of the region.This was intended to accommodate balloon framed multi-story walls that were drawn as one continuous wall stack. With recent...

October 11, 2018

Wood Wall Panels - Straps vs Hold-Downs

With the recent release of RISA-3D v17 the program now offers the user the option to use Chord Straps between floors of a wood shear wall building in lieu of using hold downs. Chord Straps are a great option for transferring tension load between floors of a multi-floor building and can be installed...

October 2, 2018

Wood Design per AWC NDS 2018 Wood Code

The new AWC NDS 2018 code has been implemented into RISA-3D v17.0 and RISAFloor v13.0. To select this code for your design, simply choose this code from the Codes tab within Model Settings.

September 6, 2017

Canadian Wood Design Updates

The latest releases of RISAFloor and RISA-3D include the following updates to wood design per the Canadian codes:

April 12, 2017

CSA O86-14 Canadian Wood Code now Available

The new CSA O86-14 code has been implemented in RISA-3D v15.0 and RISAFloor v11.0

January 7, 2016

Mechanically Graded Wood Design now Available

Mechanically graded wood materials have been added for the AWC NDS 2015 design code per Table 4C, and CSA O86-14 design code per tables 6.3.2 and 6.3.3. This specification includes the updated MEL and MSR design values.

December 22, 2015

Wood Design per AWC NDS 2015 Wood Code

The latest versions of RISA-3D and RISAFloor now incorporate the AWC NDS 2015. The new provisions have been implemented in RISA-3D v14.0 and RISAFloor v10.0 and can be utilized by selecting the AWC NDS-15: ASD from the Wood dropdown menu on the Codes tab of Model Settings.

September 22, 2015

Why Did the Wood Design Values Drop?

You may notice discrepancies in the wood design values when comparing RISA with the NDS 2012 and older versions of the code. The American Wood Council updated the wood design values in the Addendum, which supersede the values used in the NDS 2012 and previous versions of the Design Values for Wood...

February 26, 2015

Canadian Wood Design now Available

Timber design per the Canadian CSA 086-2009 design code is now available. Canadian wood member design is very similar to the US NDS member design. There are slightly different load factors, material properties, shape tables, and capacity equations, but the overall modeling procedure in RISA is the...

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