Three-Dimensional Meshing

Two previous posts showed how to use Minjie's meshing functions to create line meshes for beam-column elements and 2D meshes for solid elements. This post will complete the trilogy by showing how to make a 3D mesh for solid elements. The bar shown below is the same model used in the post on 2D meshing. … Continue reading Three-Dimensional Meshing →

Glulam Volume Factor

I knew nothing about wood design until I started teaching it. Although there are accommodations for LRFD, which is all I learned as a student, wood design is entirely ASD, or allowable stress design. The required stress, f, determined from structural analysis for the controlling ASD load combination, must be less than the available stress, … Continue reading Glulam Volume Factor →

Two Paths You Can Go By

I am confident we can use OpenSees to solve every truss, beam, and frame problem from any statics or structural analysis textbook as well as every single degree-of-freedom and rigid shear frame problem from a structural dynamics textbook. We can also solve any reasonable problem from a finite element textbook. My confidence starts to wane … Continue reading Two Paths You Can Go By →

NaBloPoMo Recap

I made it through my second NaBloPoMo. 30 posts in November by strong equilibrium (one every day), not weak equilibrium (average one per day). Motivation bottomed out on November 18 when I squeaked out this post. I'm glad I managed to keep going. 15 posts contained technical information about OpenSees. The other 15 were some … Continue reading NaBloPoMo Recap →

Line Mesh

The DiscretizeMember function, which dates back many years, was recently superseded by the line mesh command, written by Minjie. In addition to creating boundaries for solid meshes, as shown in this post, you can use line meshes to discretize a frame member (2D or 3D) into beam-column elements--just pass the optional element type and arguments … Continue reading Line Mesh →

Two-Dimensional Meshing

Although the material and element models are there, OpenSees is not well known for solid finite element analysis. Creating a good mesh is key to solid FEA and there aren't many meshing tools implemented in OpenSees. The OG block2D and block3D commands work fine, but you have to manually join or tie adjacent meshes with … Continue reading Two-Dimensional Meshing →

Work on Your Cliches

Before you tell your supervisor what you've done with OpenSees, you gotta work on your cliches. Cliches don't come from nowhere. For instance, Nuke learned his cliches from Crash before he used them in The Show. https://youtu.be/SB_LjL0lUJ4 Cliches for baseball, OpenSees, and life: Play them one day at a timeI'm just happy to be hereHope … Continue reading Work on Your Cliches →

Finite Differences

A previous post showed how to compute response sensitivity by the DDM, or direct differentiation method. Comparisons with finite difference calculations verified that the DDM results were correct. In this post, I'll dig a little deeper into finite differences. The advantage of the finite difference method (FDM) is it will work for any model parameter--you … Continue reading Finite Differences →

Full Credit

I've been reading the Austin Kleon "trilogy on creativity" and making connections with OpenSees. In the second book, Show Your Work!, Kleon explains why and how you should always credit the creators of work you share. Or, in the world of OpenSees, the creators of work you remix then share. Sure, the creators of the … Continue reading Full Credit →

Happy Franksgiving

OpenSees is the result of Frank's giving. So send him an e-mail to say thank you. I knew this portmanteau would not be novel. After a quick Google search, I was surprised to learn that Franksgiving was an episode in United States history, ultimately leading to Thanksgiving being celebrated on the fourth, instead of last, … Continue reading Happy Franksgiving →