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 When you watch the video, replace "outdated library" with "OpenSees", "Java" with "Tcl", and "Minecraft" with "incremental dynamic analyses for a portfolio of 3D reinforced concrete frames".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

Multiple-Support Excitation

Structural systems typically have different ground accelerations at supports separated by long distances. These systems can be a single structure such as a long span bridge or multiple structures in a region. While most OpenSees analyses use uniform excitation with effective earthquake forces applied to the dynamic DOFs of the model, the framework also accommodates … Continue reading Multiple-Support Excitation