Author: Michael H. Scott

I have been involved in the development, maintenance, and growth of OpenSees since its early days. I am interested in learning Python and improving my academic writing.

Non-Convergence Does Not Mean OpenSees Crashed

I once had the following conversation with a concerned user (CU) of OpenSees: CU: "I was running a response history analysis, then all of a sudden OpenSees crashed." PD: "Really, it crashed? Did you get the blue screen of death?" CU: "No. The analysis stopped and I saw 'Failed to converge'. It crashed." PD: "Oh, … Continue reading Non-Convergence Does Not Mean OpenSees Crashed →

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 →

Be More Specific than “Fiber Element”

I hear the term "fiber element" a lot, as in "We used fiber elements to model the response of this reinforced concrete moment frame". Usually, when people say something like this, they are referring to "force-based distributed plasticity frame elements with fiber-discretized cross sections". That is a mouthful. I can see the desire to shorten … Continue reading Be More Specific than “Fiber Element” →

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--of any genre--that you've probably never heard of. In his 2004 track "All Caps" with Madlib, DOOM explains how his stage name should be written. All CAPS when you spell the man's name. MF DOOM, 2004 The preferred capitalization of OpenSees is not so clear. I often see … Continue reading No CAPS When You Spell the Framework’s Name →

Be Careful with Modal Damping

Modal damping is kind of the it-spell in the dark art that is modeling viscous damping in structures. Although modal damping is pretty straightforward, you should be aware of an important aspect of its implementation in OpenSees. The issue, which is described in section 9 of this paper, is that OpenSees assembles the dynamic tangent … Continue reading Be Careful with Modal Damping →