9.1 Spring/Dashpot Behavior

The specification of spring/dashpot elements requires a special input syntax in table 'MATERI' as outlined in this chapter. The following models are available to specify the stiffens and damping of spring/dashpot elements.

Linear elasticity.

This model is simply specified by the spring stiffness [§9.1.2.1]. It may be used in linear analysis.

Nonlinear elasticity.

For all spring elements nonlinear elasticity may be specified via a multilinear spring stiffness diagram [§9.1.2.2]. The spring follows this diagram both for loading and unloading. You may specify multiple spring diagrams to model unloading-reloading cycles [§9.1.2.2]. Alternatively, for translation springs you may specify nonlinear elasticity via a multilinear force-elongation diagram [§9.1.2.3]. The nonlinear elasticity models may be used in nonlinear analysis.

Plasticity.

For the plasticity model a maximum and minimum admissible force (translation spring) or moment (torsion spring) must be specified [§9.1.3]. The plasticity model may be used in nonlinear analysis.

Damping.

Specification of damping coefficients for spring/dashpot elements causes these elements to act as dashpots, i.e., simulating continuous damping [§9.1.4].

In addition to these models, you may specify an initial strain in regular translation and torsion spring elements [§9.1.1].