The "Damper" type link element in SAP2000 has two distinct set of properties. The linear properties of "Effective Stiffness" and "Effective Damping" are used in linear analysis cases and assumed to be in parallel. The nonlinear properties of "Stiffness", "Damping Coefficient" and "Damping Exponent" are used for nonlinear analysis cases and assumed to be in series. If the user does not need to use a "Damping Exponent" other than 1 they can use the "Linear" type link element. This allows the use of a linear dashpot with a linear stiffness in parallel Two sets of properties are available to dampers, a type of link object, including:
- Linear properties, where Effective Stiffness and Effective Damping may be specified for linear analysis cases. By default, these parameters are modeled in parallel; and
- Nonlinear properties, where Stiffness, Damping Coefficient, and Damping Exponent are specified, and modeled in series. A linear link object is most suitable unless nonlinear damping is assigned using a Damping Exponent other than 1.0. This enables the modeling of a linear dashpot in parallel with linear stiffness for both linear and nonlinear analysis cases.