# Concrete02 with Control of the Initial Stiffness

Although they have the same compressive envelope, Concrete02 offers more features than Concrete01--tension strength, tension stiffening, and compressive unloading/reloading loops. However, one thing Concrete02 (and Concrete01) lacks is control over the initial stiffness, which is fixed at $latex E_c=2f'_c/\varepsilon_{c0}$. To overcome this limitation with Concrete02, Dr. Nasser Marafi created Concrete02IS (Concrete02 with control of the … Continue reading Concrete02 with Control of the Initial Stiffness

# Elastoplastic Calibration

You can do a lot with UniaxialMaterials in OpenSees--springs, fibers, trusses, section aggregators, etc. Although over 130 UniaxialMaterials are available, it's likely that only about a dozen see regular use. So, with all due respect to Concrete23, my favorite regular is HardeningMaterial. It's straight out of Simo and Hughes and was the example material for … Continue reading Elastoplastic Calibration

# Uniaxial Multi-Tool

Uniaxial, or one-dimensional, material models are the work horses of OpenSees. Originally developed for the truss element, these models have proliferated thanks to fiber section models. However, because they are simply scalar functions, UniaxialMaterial models can be used in several other contexts. The calling function knows the context, not the UniaxialMaterial model--it only provides an … Continue reading Uniaxial Multi-Tool