October 10, 2019

RISA-3D Training - Minneapolis, MN - August 18-19, 2020

The RISA-3D training classes are a great way to receive instruction from the RISA experts while working on real-world examples that allow you to quickly master RISA software, take advantage of the latest features, streamline engineering and tackle modeling complexities.

This two-day regional RISA-3D training will be held in Minneapolis, MN on August 18-19, 2020 at the Renaissance Minneapolis Hotel and includes the following classes:

Basics of Structural Modeling (Day 1)
Advanced Structural Modeling (Day 2)

For more information and to register for this course, use the link below:

RISA-3D Training - Minneapolis, MN

For more information on the venue, the Renaissance Minneapolis Hotel, The Depot click the button below:

Renaissance Minneapolis Hotel, The Depot

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Tags: RISA-3D, New, Training

August 20, 2015 | RISA-3D, New

Residual Rigid Response (Dynamics)

When running a Response Spectrum analysis for seismic design, the response for high frequency modes can be included without solving for their individual mode shapes. This is often done to save analysis time and memory. This topic discusses some of the technical background and gives references for RISA’s implementation of this method. Simple Overview It can be difficult to achieve the 90% mass participation required by ASCE 7 for a response spectra / modal analysis. This is especially true for structures that have a large amount of mass at the lower levels of the structure. This mass will often be associated with very rigid modes. These modes may be so rigid that it may not be necessary to calculate the actual eigen modes. Instead, their response can be estimated accurately (and much more efficiently) using some simple estimates of their response. This is done by figuring out what mass has been activated already with the currently solved eigen modes. This tells us where “missing mass” is that has not been activated. If one applies a response spectra acceleration equal to the zero period acceleration to this mass, then this should provide a reasonable estimate of the residual or missing mass…

March 31, 2020 | RISA-3D, Webinar, New, Events

WEBINAR: Metal Building Design in RISA-3D

Prefabricated metal buildings utilized steel for their internal support as well as exterior cladding. These structures are used for their constructability and flexibility in a variety of applications including storage, work spaces and living accommodations. RISA-3D empowers users to easily model, load, analyze, design and document metal buildings with standard shapes as well as tapered wide flanges. Join us on April 14th, 2020 at 2pm EST (11am PST) to learn how to: Utilize a DXF in the creation of a complete metal building Quickly apply gravity & lateral loading Apply appropriate bracing conditions for proper steel design Review results and create a complete engineering report PDH Credits: 1.0 PDH credit will be sent to all attendees based on the email address used to register for the webinar. PDH credits cannot be sent to multiple people based on a single registration. If you wish to view the webinar as a group, please have each person in the group register individually and then after the webinar, email info@risa.com with a list of all group attendees. PDH credits will be sent out to these people as long as there is a corresponding registration. If you missed the webinar, you can use the link…

April 3, 2012 | Seismic, Dynamics, RISA-3D, RISA-2D, New

Why Don’t My Response Spectra Reactions Satisfy Statics?

The applied loads in a response spectrum analysis (RSA) are the applied masses times the accelerations in the response spectra. Each mode of vibration produces its own set of joint reactions. The reactions for each mode obey statics as shown in the portal frame example shown below: Response Spectrum Analysis involves the statistical combination of the response from multiple modes. A loss of sign results when the individual modal results are combined together to form the total RSA result. Below is an example of the equations used for Square Root Sum of Squares (SRSS) method: The above equation makes it clear that the final results for R1 and R2 will have the same sign despite the fact that individual modal results (R11 and R21) may have had opposite signs. If this were a statically applied lateral load, the reactions would be equal and opposite with a total net upwards reaction of zero. It is possible for the model to approximately match statics if the option to Use Dominant Mode for Signage is selected. This option merely looks at the reactions for the mode with the highest % mass participation and assigns a positive or negative sign to each joint reaction…