November 13, 2019

Solving P-Delta Divergences in RISA-3D

In this video, you’ll learn how to investigate your RISA-3D model for P-Delta divergence errors. This type of error is common in general structural analysis software and has two major causes: a model that is unstable or a model that is too flexible. For this investigation, two separate steel frame models will be used to evaluate a workflow to solve P-Delta issues.

Tags: RISA-3D, v18, New, Instability, P-Delta

April 13, 2011 | Seismic, RISA-3D, New

How Do I Change the Member Type in RISA-3D?

In RISA-3D, there are many different applications that require you to define Member Type in your model including AISC 15th Edition steel design, Seismic Design, Concrete design, and models that will be transferred to Autodesk Revit. If you find yourself at the end of the project and you forgot to set the member type, here are the steps to easily modify the model. Scenario 1: Section sets were not used. Simply select the member(s) whose type you would like to change, then change the Member Type via the Properties panel on the left hand side. Scenario 2: Section sets were used to build the model. Simply open the Section Sets spreadsheet and change the Member Type as shown below. You can use the Member Color icon to display the Member Type graphically…

March 30, 2020 | RISA-3D, New, Steel

How Can I Optimize My Members in RISA-3D?

In RISA-3D when drawing members you must start with initial sizes. After loading and load combinations are completed the model is solved and then member design must be done, making sure that members pass for both strength and serviceability considerations. For both strength and serviceability considerations, RISA-3D has the ability to provide Suggested Design results to help optimize member design. To access the suggested design, first make sure that results are available and then click on the Suggested Design button found on the Results tab. These suggested shapes are either based on Section Sets if used, or on individual members. For Section Sets the program will find the worst case member code check within each Section Set. Based on that member the program will provide a suggestion of a shape that will work that is either bigger or smaller depending on whether the code check is failing or passing by a large margin. For individual members, the suggestion is made based just on that member. If a member or Section Set does not show up in the list that tells you that either the current section is optimal or a section cannot be found to meet strength criteria. If you…

March 3, 2011 | Seismic, RISA-3D, Loads, New

How to Use Seismic Factors in Load Combinations in RISA-3D

RISA-3D now has the ability to define the seismic parameters Rho, Omega and SDS directly into load combinations. If you open the Basic Load Cases spreadsheet and click into the BLC column, the dialog offers the ability to add these values in to factor the load. Here we will see that Rho and Omega can only be used if the Load Category Code is set to a seismic option. Sds can only be used if Dead Load is selected. Once you apply this factor it is automatically taken into account without the use of the Factor column in the Load Combinations spreadsheet. The actual values for these factors are defined in the Seismic tab of Global Parameters. Rho is specified in section 12.3.4 of the ASCE 7-16. Omega is specified in Table 12.2-1. SDS is used for the vertical portion of seismic load and is typically multiplied by 0.2*DL in Section 12.4 combinations…