The question of whether to use the force-based or displacement-based formulation for material nonlinear frame analysis is one that comes up a lot. The answer depends on a few factors, mostly the material and the element length. To get a sense of the basic issues, I will compare the two element formulations with a numerical … Continue reading A Tale of Two Element Formulations
Tag: OpenSees
OpenSees Time Machine
I recently found two Zip disks in my office. They were the next big thing for about 15 minutes in the late 1990s and early 2000s. I then got my hands on an external Zip drive and was able to offload the disks' contents. One disk has lecture notes and assignments from a few graduate … Continue reading OpenSees Time Machine
Behind the Elastic Interior
If VH1 expanded its list of the top one hit wonders of the 2000s to include journal articles in structural engineering, Scott and Fenves (2006) would be right up there with James Blunt and Gnarls Barkley. Actually, Google Scholar puts the article up there with some pretty nice company. Like all journal articles, there's something … Continue reading Behind the Elastic Interior
Torsion with Fiber Sections
I won't blog about every pull request to OpenSees on GitHub, but I will blog about pull requests that could affect backward compatibility of user scripts. Pull request #142 is one such case. It affects how torsion is added to fiber sections in three-dimensional models. The frame elements require torsional stiffness in order to prevent … Continue reading Torsion with Fiber Sections
Is Plastic Hinge Integration a Fruit or a Vegetable?
If distributed plasticity elements are fruits and concentrated plasticity elements are vegetables, then plastic hinge integration is something like a tomato. Based on papers I've read, manuscripts I've reviewed, presentations I've seen, etc., there's some confusion as to whether plastic hinge integration is a fruit or a vegetable. Here's my two cents. Concentrated plasticity elements … Continue reading Is Plastic Hinge Integration a Fruit or a Vegetable?
How to Cite OpenSees
In the $latex R^{42}$ space that defines academic performance evaluation, citation-based metrics comprise a small but often over-emphasized subspace. Based on the developers' Google Scholar profiles, it is clear that OpenSees generates a lot of citations from various corners of cyberspace. In the citation-stingy field of structural engineering, the numbers are impressive. On the other … Continue reading How to Cite OpenSees
No CAPS When You Spell the Framework’s Name
MF DOOM is one of the greatest lyricists (rap or otherwise) that you've probably never heard of. In his 2004 track "All Caps" with Madlib, DOOM states that his stage name should be written in all caps. All CAPS when you spell the man's name.MF DOOM, 2004 The preferred capitalization of OpenSees is not so … Continue reading No CAPS When You Spell the Framework’s Name
