OpenSees Modeling Capabilities
Separate from the computational and problem solving classes, are classes for building models (termed ModelBuilder classes). The Version 0 release of OpenSees includes a general modelbuilder for creating threedimensional frame and continuum models using TCL. Users can generate models using TCL procedures, and are encouraged to share these generation procs with others! Additional ModelBuilder classes suited to a particular type of model may also be developed.
Elements

Beamcolumn  3D elements with the following integration rules
 Linear elastic material (closed form),
 Concentrated plasticity integrated over specified hinge lengths, or
 Distributed plasticity integrated along the element length.
 Linear  first order geometry,
 PDelta  second order "leaning truss" transformation, or
 Corotational  large displacement transformation.
 Zero length  3D element which uses multiple uniaxial materials to model the element forcedeformation relation.

Truss  3D element with material nonlinearity modeled by
 Uniaxial material stressstrain integrated over crosssectional area, or
 Section forcedeformation relationship.
 Quad  2D bilinear isoparametric element which uses ND materials at each of its integration points.
Uniaxial Materials
 Elastic  linear elastic material tangent with optional linear damping tangent
 ElasticPP  elasticperfectly plastic
 ElasticPPGap  onesided EPP with an initial gap
 Hardening  bilinear model with combined linear isotropic and kinematic hardening
 Steel01  bilinear steel model with linear kinematic and exponential isotropic hardening
 Concrete01  concrete model with KentPark envelope, degraded linear unloading/reloading, and no tensile strength
 Hysteretic  trilinear backbone with pinching, damage, and degraded unloading stiffness
 Parallel  multiple uniaxial materials in parallel
 Series  multiple uniaxial materials in series
 BiLinear  bilinear hysteretic model with degradation
 Clough  Clough type hysteretic model with degradation
 Pinch  pinching hysteretic model with degradation
ND Materials
 ElasticIsotropic  plane stress and plane strain formulations for use with the quad element.
Section Models
 Elastic  uncoupled axial and bending response.

Fiber  discretized by fibers which collectively define section response.
The fiber models available are
 Uniaxial2d/3d  associates with a uniaxial material and enforces the Bernoulli beam assumption for axial and uni/bidirectional bending
 Generic1d/Nd  map stresses from uniaxial and ND materials to section stress resultants. For example, a uniaxial material can be used to model section momentcurvature behavior, or an ND plasticity model can be used to model section momentaxialshear interaction.
 Aggregator  combination of a section and multiple uncoupled uniaxial materials used to define additional section forcedeformation relations. For example, a fiber section can be combined with an uncoupled shear forcedeformation relation.