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.

Edit Your Copy

There's more to publishing a journal article--or any other content you want to unleash on the world--than writing some words, accepting all spell check corrections, and running your favorite AI-powered grammar checker. From conception to preservation on a virtual shelf, your journal article should go through at least five stages of editing--most stages more than … Continue reading Edit Your Copy →

Eccentrically Loaded Bolt Groups with Bolt Hole Clearance

Standard bolt holes punched in steel elements are either 1/16 inch or 1/8 inch wider than the bolt diameter. Oversized bolt holes can have larger clearances in order to make fit-up easier. While the bolt hole clearance can affect the available strength of an eccentrically loaded bolt group, Tables 7-6 to 7-13 of the AISC … Continue reading Eccentrically Loaded Bolt Groups with Bolt Hole Clearance →

What Is a Good Penalty Number?

I often see the penalty constraint handler used with seemingly high penalty numbers like the following: ops.constraints('Penalty',1e18,1e18) I'm not sure why these specific numbers are used so often in scripts, but I suspect these values were used in an old example and have been passed down. And while the 1e18 values might have worked for … Continue reading What Is a Good Penalty Number? →

The Sensitivity Is in the Details

Although the Hardening and Steel01 uniaxial materials can be calibrated to give the same response, the DDM response sensitivity with respect to the same parameter can be different due to how the material models are implemented. Consider the truss model from a previous post on minimal DDM examples. The stress-strain response shows the elastoplastic tangent … Continue reading The Sensitivity Is in the Details →

How to Apply Ground Motions in Multiple Directions

A common question is can I apply ground motions in more than one direction to a model in OpenSees? The answer is Yes. Let's say you have files for three ground motion recordings: gm000.txt, gm090.txt, and gmUP.txt. Define a time series for each ground motion, then associate each time series with a uniform excitation load … Continue reading How to Apply Ground Motions in Multiple Directions →

Will OpenSees Ever Be Un-Seen?

OpenSees contains sophisticated solution algorithms and element and constitutive models for simulating the nonlinear response of structural and geotechnical systems to natural and human-made hazards. But sometimes these sophisticated models are put to less than sophisticated use. I've been kicking this idea around in my head for a while, but what xykademiqz wrote in a … Continue reading Will OpenSees Ever Be Un-Seen? →

Rectangular Hollow Structural Sections

A hollow structural section (HSS) is manufactured from steel and is either rectangular, square, or circular. This post will address rectangular HSS, inclusive of square HSS. Round HSS is a little easier to define and will be the subject of another post. There are a couple options in OpenSees for defining material nonlinear rectangular HSS … Continue reading Rectangular Hollow Structural Sections →