March 3, 2020

How to Review Your Batch and Envelope Results

RISA-3D provides users a variety of solution options, allowing results to be catered to specific project needs. In many situations it is beneficial to be able to view both the envelope and batch results for a model without having to run two separate solutions. An example of this would be when you want to optimize the member for the maximum forces, but also to be able to further investigate the detail report for a load combination that controls a specific limit state.

When the 'Envelope (Only) of Marked Combinations' option is selected for a model that contains multiple load combinations, the results are enveloped to show only the minimum and maximum results. If the 'Batch Solution of Marked Combinations' option is selected with the Include an Envelope with the Batch checkbox not checked, the results will be displayed for each load combination.

However, with the 'Batch Solution of Marked Combinations' option selected and the 'Include an Envelope with the Batch' selection checked, an envelope and batch solution will both be available.

Once you have this option selected, click Solve. When the model completes the analysis, your results will be available in the Results toolbar.

Toggling between 'Env' and 'Batch' options on the Results toolbar will determine if the spreadsheets for the enveloped or batched results will open, respectively.

Alternatively, results spreadsheets can be accessed by navigating to the Results tab on the Ribbon toolbar.

You also have the option to display Envelope node reactions and node reactions by load combination graphically. You can do this by navigating to the View tab on the Ribbon toolbar and select Results under the View Settings.

In the dialog that appears, you can toggle between the option to Display Results for Load Combination or Envelope. When Envelope is selected, the controlling maximum and minimum reactions for all solved combinations will be shown graphically.

From that same dialog, you may also view member results graphically by selecting the Members tab. You still have the option here to toggle between Display Results for Envelope or Load Combination.

Tags: RISA-3D, Results, New

May 24, 2010 | RISA-3D, RISA-2D, New, Analysis, Eccentricity

Define a Beam Eccentricity in RISA-3D

When you have a deep column, it is necessary to model the beam so that it connects to the face of the column. This results in an eccentricity at the joint. RISA-3D offers two ways to model this eccentricity. Open the Members Spreadsheet and go to the Advanced tab. There are two options labeled I Offset and J Offset. These represent the offset at the start (I) and end (J) of the member, respectively. You may also specify the I Offset and J Offset by first selecting the beam, and modifying the Additional Properties section of the Properties Grid. For the beam member you can either enter the exact value of the member offset (i.e. half the depth of the column) or you can enter the column member number. If you enter the column member number the program will automatically calculate the offset assuming half the column depth. This feature is very useful because it will automatically update the offset value when you change the column size. Please note that using the offset feature will reduce the total length of your beam by the offset amounts which will affect your design code check calculation. For example, in a portal frame…

July 13, 2023 | RISAFloor

Tips for Solving a Slow Solution in RISAFloor

Is your RISA software solution running slower than you expected? There are a few things you can do during your model set up in order to make your model more efficient and reduce the solution time. RISA has compiled a list of our most common tips for solving a slow solution in RISAFloor. 1. Is your Analysis Mesh too Small? RISA software uses a finite element analysis mesh to analyze and solve the structural model. By default, the FEA mesh size is set to 24 inches. RISA users have the ability to reduce the mesh size. However, reducing the FEA mesh size causes the program to generate a much finer mesh which takes a longer time to solve. If your model solution is very slow, we suggest reviewing these FEA mesh size settings. You may need to increase this mesh size. This mesh setting is found in your Model Settings, then open the Solution tab. 2. Do you have a Large Number of Unused Nodes? How does this happen? Unused nodes can be lingering from previously deleted elements or perhaps maybe even accidentally drawn from the Node Spreadsheet. They may be tightly packed or close to other used nodes. In…

February 23, 2012 | RISA-3D, RISA-2D, New, Analysis, Instability, P-Delta

How Do I Resolve a P-Delta Instability?

Investigating P-Delta instabilities in RISA-3D (or RISA-2D) can be difficult. The first step is usually to solve the model without the P-Delta effect included to see if there are any obvious deflection problems that could cause issues with a P-Delta analysis. But, what can be done when this doesn’t yield any obvious issues? It helps to think of a P-Delta failure as an elastic buckling of your model. It may be a localized buckling of one member, or it may be a general buckling of the frame. The challenging part to understanding the failure is to determine what the buckled shape of the structure looks like. Since the program doesn’t give any results for a P-Delta divergence, the user needs to reduce the loading to the point where the structure is very close to buckling. Take a look at the screen shot below. Of the normal Load Combinations, LC#2 is the one which diverges for P-Delta. Therefore, we have created a number of load combinations to test this P-Delta failure. These load combination apply a fraction of the load (from 10% to 93%) from LC#2. In this way, we are reducing the load to a point where the structure is…