This command is used to construct a catenary cable element object.
element('CatenaryCable', eleTag, iNode, jNode, weight, E, A, L0, alpha, temperature_change, rho, errorTol, Nsubsteps, massType)
unique element object tag
end nodes (3 dof per node)
elastic modulus of the cable material
cross-sectional area of element
unstretched length of the cable
coefficient of thermal expansion
temperature change for the element
mass per unit length
allowed tolerance for within-element equilbrium (Newton-Rhapson iterations)
number of within-element substeps into which equilibrium iterations are subdivided (not number of steps to convergence)
Mass matrix model to use (
massType= 0 lumped mass matrix,
massType= 1 rigid-body mass matrix (in development))
This cable is a flexibility-based formulation of the catenary cable. An iterative scheme is used internally to compute equilibrium. At each iteration, node i is considered fixed while node j is free. End-forces are applied at node-j and its displacements computed. Corrections to these forces are applied iteratively using a Newton-Rhapson scheme (with optional sub-stepping via $Nsubsteps) until nodal displacements are within the provided tolerance ($errortol). When convergence is reached, a stiffness matrix is computed by inversion of the flexibility matrix and rigid-body mode injection.
- The stiffness of the cable comes from the large-deformation interaction between loading and cable shape. Therefore, all cables must have distributed forces applied to them. See example. Should not work for only nodal forces.
- Valid queries to the CatenaryCable element when creating an ElementalRecorder object correspond to ‘forces’, which output the end-forces of the element in global coordinates (3 for each node).
- Only the lumped-mass formulation is currently available.
- The element does up 100 internal iterations. If convergence is not achieved, will result in error and some diagnostic information is printed out.