December 16, 2015
Concrete Design per ACI 318-14 Concrete Code now Available
The new ACI 318-14 code has been implemented into RISA-3D v14, RISAFloor v10, and RISAFoundation v8.
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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The new ACI 318-14 code has been implemented into RISA-3D v14, RISAFloor v10, and RISAFoundation v8.
RISAFloor is a design program in which it takes basic shape criteria about your beam or column members and then selects an optimal size to meet strength and serviceability criteria. However, the program can just as easily perform a design check for an as-built condition by defining specific member...
Have you been in RISAFloor performing a steel product design and noticed an (SP) extension to a joist designation? The following will discuss when the program designs for these special loading conditions.
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...
The beams in a lateral force resisting system, such as a braced frame or moment frame, typically carry a significant axial force. In the example below (with no diaphragms) the beam (M4) carries a significant axial tension.
Revit offers two options for setting the elevation of beams. The way these are used has a significant impact on how those members are round tripped to RISAFloor, so it is important for you to use them correctly. The Level Offsets are available at each end of the beam. They can be modified through...
In the Seismic Loads dialog there is a checkbox for “Include structure weight in base shear”.
RIAFloor designs the gravity system and then integrates with RISA-3D to design the lateral system. Only the lateral members are taken from RISAFloor over to RISA-3D. The loading is automated in this integration so one of the most common questions is: what loads are transferred when switching from...
There are multiple options in RISA-3D and RISAFloor to create a custom shape not available in the program databases. The first, is to utilize RISASection in order to create cross-sections, calculate section properties and import the shape directly into RISA-3D. For more information on integrating...
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