March 30, 2020
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 agree to use a suggested shape then you can check the Use Suggested? checkbox and press the Replace Current Shapes button.
This will physically replace your shapes with the suggested shapes and then re-solve the model. Because the stiffness of the model changes with the new shapes it is an iterative process and you may need to run the optimization multiple times.
The optimization for each Section Set or member is controlled by both the Design List and the Design Rule.
The Design List defines which members can be used in the optimization. You can find additional information about Design Lists by reviewing the following article.
The Design Rule is defined in the Member Design Rules spreadsheet and within the Design Rule you can limit the size of the sections, the code check or set specific deflection requirements.
For more information on how to optimize members for both strength and serviceability considerations, review the video below.