May 10, 2018

Viewing Design Foundations in RISA-3D

RISA-3D v16 now includes the added ability to view foundations designed in RISAFoundation. This feature proves useful as it gives a way for engineers to see if foundations have been sized appropriately for the loading from RISA-3D. For more information about how foundations can be shown in RISA-3D, view the video posted to YouTube.

Tags: RISA-3D, New, Foundations

October 4, 2018 | RISA-3D, New, Analysis

Partial Fixity End Releases in RISA-3D

RISA-3D v17.0 now has the ability to model partial fixity member end releases. Partial fixity end releases can be utilized in RISA to model the behavior of a partially restrained or semi-rigid connection that cannot be idealized as fully fixed or pinned. Partially restrained connections are common in seismic moment frame systems and their semi-rigid rotational behavior can now be modeled in RISA-3D. A partial fixity end release reduces the rotational stiffness at the member end joint by applying a rotational spring constant value entered by the user. RISA-3D uses the Euler-Bernoulli beam formulation to introduce this spring constant in the stiffness matrix. Partial fixity end releases can be applied in the Properties Panel by clicking on the ellipses the I or J end release cell: Once a rotational stiffness is applied, the connection at that member’s joint will become more flexible as they are partially restrained. Graphically, the end release will show a symbol to designate that a partial fixity end release has been assigned. In the three examples above, the various frames have a beam to column connection that is either fixed, partially restrained, or pinned. The second frame beam has a rotational partial fixity member end release…

February 15, 2022 | RISA-3D, New, UI, Interface, View

Easily view specific data using Viewer Mode in RISA-3D

RISA-3D is a robust tool for the analysis and design of a variety of different structures. Whether users are creating simple or incredibly complex models, the need to be able to easily review precise results and create corresponding screenshots is paramount. As a result, RISA-3D Version 20 now includes Viewer Mode which allows users to quickly show element information only for selected elements. Additionally, both input and result spreadsheets are also automatically filtered based on which elements are selected. What is Viewer Mode? When Viewer mode is enabled, only the elements that are displayed or selected will graphically display information. This applies to element labels, code checks, force diagrams or any other information that is displayed on the elements. By default, spreadsheets will also automatically filter to reflect the elements that are currently selected in the 3D view. Enabling & Using Viewer Mode Viewer Mode can be activated by clicking on the "eye" icon found in the 3D View's "Selection Toolbar". When this icon is green this means Viewer mode is enabled. Additionally you will see a green border around the 3D View when Viewer mode is enabled. With Viewer Mode active you can simply single click an element to…

May 4, 2015 | Dynamics, RISA-3D, RISA-2D, New

Ritz Vector Solver (Dynamics) now Available

RISA-3D v13 includes a new Ritz Vector Solver for the Dynamic analysis. When running a Response Spectrum analysis for seismic design, some structures experience large numbers of local modes that don’t contribute to the lateral response of the structure. The use of load-dependent Ritz vectors (rather than true mode shapes) can greatly improve the speed and accuracy of a Response Spectra analysis for these types of models. There is a new option added to the Dynamic solution options as shown to the right. This dialog can be found by clicking on the Advanced button from the Solution tab of the Model Settings. RISA-3D Output In general, the Ritz vectors will be very similar in shape and frequency to the true dynamic results, though they are not expected to be identical. For that reason, the RISA-3D results will identify them as Ritz Vectors (rather than Mode Shapes) and Ritz Frequencies in the title bar of the dynamic results spreadsheets. Simplified Overview The general concept is that a static solution in the direction of the seismic loading will form a good basis for the approximate mode shapes of the structure which then leads to natural frequency calculations. This concept is nothing new…