$matTag

Unique material object integer tag.

$tzType

tzType = 1 Backbone of t-z curve approximates Reese and O'Neill (1987) relation.

tzType = 2 Backbone of t-z curve approximates Mosher (1984) relation.

$tult

Ultimate capacity of the t-z material. Note that "t" or "tult" are distributed loads [force per length of pile] in common design equations, but are both loads for this uniaxialMaterial [i.e., distributed load times the tributary length of the pile].

$z50

Displacement at which 50% of tult is mobilized in monotonic loading.

$c

The viscous damping term (dashpot) on the far-field (elastic) component of the displacement rate (velocity). Default = 0.0. Nonzero c values are used to represent radiation damping effects.