September 15, 2020
CD Factor for Wood Hold-Downs
If you have utilized Hold-Down's in RISA-3D, you have mostly likely noticed that a value of CD is reported for each selection in the database. However, it may not be clear how it is being used?
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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If you have utilized Hold-Down's in RISA-3D, you have mostly likely noticed that a value of CD is reported for each selection in the database. However, it may not be clear how it is being used?
In the Node Reaction spreadsheet, all reactions from node-based boundary conditions are reported. If you look closely at some models, there may be wall panel labels in the Node Reactions spreadsheet as well. This may cause users to ask the question:”what are these reaction values for a...
Introduction In the design of two-way post-tensioned slabs, whether it be by use of unbonded or bonded tendons, precompression or “average minimum precompression,” is a critical serviceability requirement in ACI318. It is used to serve as a means for selecting a prestressing force and/or quantity...
Learn how to build custom steel and concrete shapes using RISASection and then import them into RISA-3D to incorporate them in analysis and design.
Modeling complex structures in any structural analysis and design software can be cumbersome. ADAPT-Builder provides users with straightforward modeling operations and functionality within an easy to navigate user interface which allows for efficient model creation. The resources below outline the...
Open web steel joist design is now available in RISACalc per the SJI 43rd/44th and 42nd Editions! The available joist series include K-Series, LH-Series, DLH-Series, SLH-Series (42nd Edition only), and KCS joists.
When determining the Depth of Compression Block value of ‘a’ in a Masonry Wall design based on the equation a = (As * fy)/(0.8 * fm * b) in a RISA-3D model, it is possible to see a small variance in the program results versus a traditional hand calculation using this typical equation. The reason...
Modeling and analyzing structures for dynamic conditions is essential to understanding how a structure will react to loading such as wind and seismic. These analysis types can include simple free vibration analysis as well as more advanced response spectra and time history analysis. RISA-3D is...
In this video, we’ll take a look at the modeling and analysis of a mat slab in RISAFoundation. We’ll specify design parameters and soil properties to be able to obtain reinforcement design and view soil pressure contour diagrams.
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