Recording the response of a single fiber in a fiber section is a common ask. You will need to use an Element recorder, but what you can record in each fiber is defined in the UniaxialMaterial::setResponse() method. The most common option is 'stressStrain', which gives the fiber stress-strain response history. After setResponse() drills down to … Continue reading How to Record Fiber Response
Tag: Fiber sections
You Gotta Keep ’em Aggregated
The SectionAggregator was one of my few useful OpenSees ideas. This class gives a flexible way to combine, or aggregate, modes of force-deformation in a single section model. The idea for SectionAggregator came from the Decorator software design pattern, the same pattern from which so many UniaxialMaterial wrappers were spawned (here and here). In fact, … Continue reading You Gotta Keep ’em Aggregated
Fiber Section Centroids
If you define a fiber-discretized cross section in OpenSees using section coordinate systems A and B shown below, will you get the same response when you apply axial load and bending moments to the sections? The answer is yes. You will get the same response from sections A and B. The fiber sections compute the … Continue reading Fiber Section Centroids
Close to the Edge
A colleague in Eastchester tweeted this graphic, created by Stephen Ressler. It's a fun interpretation of social distancing, but a little abstract compared to other, more concrete, guidelines going around. For example, in Florida, the rule of thumb is to maintain a distance equal to an adult alligator length. You can visualize an alligator, but … Continue reading Close to the Edge
The Fiber Content of OpenSees
OpenSees is pretty well known for its fiber sections. Although fiber sections are not unique to OpenSees, where else can you choose from 23 uniaxial concrete models and 18 uniaxial steel models to define a reinforced concrete section? There's also a handful of multiaxial material models that capture the interaction of axial and shear stresses … Continue reading The Fiber Content of OpenSees
Torsion with Fiber Sections
I won't blog about every pull request to OpenSees on GitHub, but I will blog about pull requests that could affect backward compatibility of user scripts. Pull request #142 is one such case. It affects how torsion is added to fiber sections in three-dimensional models. The frame elements require torsional stiffness in order to prevent … Continue reading Torsion with Fiber Sections
Be More Specific than “Fiber Element”
I hear the term "fiber element" a lot, as in "We used fiber elements to model the response of this reinforced concrete moment frame". Usually, when people say something like this, they are referring to "force-based distributed plasticity frame elements with fiber-discretized cross sections". That is a mouthful. I can see the desire to shorten … Continue reading Be More Specific than “Fiber Element”
