Non-Prismatic Frame Elements

Long before the BeamIntegration abstraction, there was only Gauss-Lobatto integration for force-based elements, with a single section model copied to each integration point. This made it impossible to use a single element to simulate the response of an RC member with different reinforcing details along its length, or any member that was inherently non-prismatic. While … Continue reading Non-Prismatic Frame Elements

Every OpenSees Tutorial

There's plenty of excellent OpenSees tutorials online. But some other OpenSees tutorials feel like this sardonic, mock programming tutorial. When you watch the video, replace "outdated library" with "OpenSees", "Java" with "Tcl", and "Minecraft" with "incremental dynamic analyses for a portfolio of 3D reinforced concrete frames". https://youtu.be/MAlSjtxy5ak Pretty accurate, right? Let me know in the … Continue reading Every OpenSees Tutorial

Direct Moment-Curvature

That the force-based frame element and fiber sections are in an open relationship should come as no surprise. The displacement-based and mixed frame elements can use fiber sections and all three element formulations can use stress resultant sections. While this post used a coupled stress resultant plasticity model, you can also use the section aggregator … Continue reading Direct Moment-Curvature

Making Sense Out of Concrete02

Those three extra parameters for Concrete02 are usually enough to make me stick with Concrete01. I struggle to come up with good values for the parameters $latex \lambda$, $latex f_t$, and $latex E_{ts}$ shown in the following image from the OpenSees Concrete02 wiki page. Image developed by Dr. Silvia Mazzoni The four compressive backbone parameters … Continue reading Making Sense Out of Concrete02

Parameter Updates in the Loop

Besides visualization and writing output to files, there's some pretty useful things you can do during an OpenSees analysis. One of those things is updating model parameters. Before getting into parameter updating, it is worth showing that OpenSees analyses can be run one step at a time. Many examples online show a dynamic analysis, e.g., … Continue reading Parameter Updates in the Loop