The Hard Dynamics

I am confident that you can use OpenSees to solve all reasonable problems from textbooks on statics, structural analysis, finite elements, structural dynamics, and (most of) strength of materials. But what about engineering dynamics? The rigid body dynamics that's way more difficult than deformable body dynamics. You know, kinematics and kinetics of particles and rigid … Continue reading The Hard Dynamics →

A Better Way to Find Memory Leaks in OpenSees

In a previous post, I explained how to find a memory leak in OpenSees. The basic idea was to put the analysis inside a loop, run the loop a million times, and monitor your operating system for increasing memory usage. A perfectly fine leak hunting approach--as long as you are willing to monitor your operating … Continue reading A Better Way to Find Memory Leaks in OpenSees →

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 →