Eccentrically Loaded Bolt Groups

Tables 7-6 through 7-13 of the AISC Steel Manual contain values for C, the effective number of bolts that resist shear in eccentrically loaded bolt groups. For example, in a bolt group with three vertical rows of 4 bolts spaced s=3 inch with srow=3 inch row spacing and a load at $latex \theta$=30 degrees from … Continue reading Eccentrically Loaded Bolt Groups →

On OpenSeesing Well

Every modern motivational technique, strategy, and hack boils down to implementing William Zinsser's advice from On Writing Well. Decide what you want to do. Then decide to do it. Then do it. William Zinsser OpenSees is no different. Decide what you want to OpenSees. Then decide to OpenSees it. Then OpenSees it.

More Ado About Damping

Only a few years ago I realized that you do not have to use natural frequencies--you know, the ones you obtain from an eigenvalue analysis--to compute Rayleigh damping coefficients. This may not be news to some of you--I am often a little slow on the uptake. But I actually read a couple papers (here and … Continue reading More Ado About Damping →

Sometimes Tags Don’t Matter

When building a model in OpenSees, you have to ensure that you have unique tags for your domain components (nodes, elements, patterns, time series, parameters, etc.), reliability components (random variables, limit state functions, etc.), and model building components (materials, sections, beam integrations, etc.). If you define a duplicate tag, you will get an error message. … Continue reading Sometimes Tags Don’t Matter →

OpenSees Smarter, Not Harder

Having established the use of OpenSees as a verb, you knew adverbs that describe how one OpenSeeses wouldn't be far behind. For example: How did it go today?I OpenSeesed slowly. I had planned to build a frame model but got distracted by kitten videos. How was the workshop?It was good. I learned some useful tips … Continue reading OpenSees Smarter, Not Harder →

A Simple Material Tester

A UniaxialMaterial tester was my first foray into Tk widgets back in the early 2000s. The tester has come along for the ride through all the OpenSees source code repositories. First cvs, then svn, and now GitHub. You could select various materials and drag the slider back and forth to see the stress-strain response history. … Continue reading A Simple Material Tester →

Multi-Threaded SDF Analysis

A previous post showed that, when compared to a couple of brute force approaches, using the sdfResponse command is the most computationally efficient approach to generating an earthquake response spectrum. During an OpenSees Cafe, Dr. Silvia Mazzoni suggested taking a more intelligent approach by "batching" the brute force SDF analyses. Instead of analyzing one oscillator … Continue reading Multi-Threaded SDF Analysis →

Bad OpenSees Turkey Jokes

Today is Thanksgiving in the United States. A holiday meant for gratitude that has morphed into a day of eating copious amounts of turkey and other foodstuffs. If you have distant family members at the Thanksgiving dinner table who also use OpenSees, here are some jokes you can tell in order to break the ice. … Continue reading Bad OpenSees Turkey Jokes →

I Missed Again

When I come up with "great" exam questions, only a handful of students get the correct answer while the remaining students misunderstand the question. Same thing happens on social media. Prior to Twitter's full-on death spiral, I tweeted a quiz on the MVLEM element, a formulation available in OpenSees for modeling shear walls. Only 5 … Continue reading I Missed Again →

Writing that Shines

Not every journal article has groundbreaking technical content. Some articles barely move the needle or don't move the needle at all, while others move the needle backward. As an author, you should know when the manuscript you're about to submit is (might be) groundbreaking as opposed to a needle nudger. Regardless, if the manuscript is … Continue reading Writing that Shines →