.. include:: sub.txt ================================ Triple Friction Pendulum Element ================================ .. function:: element('TripleFrictionPendulum', eleTag,*eleNodes,frnTag1, frnTag2, frnTag3, vertMatTag, rotZMatTag, rotXMatTag, rotYMatTag, L1, L2, L3, d1, d2, d3, W, uy, kvt, minFv, tol) :noindex: =============================================================== =========================================================================== ``eleTag`` |int| unique element object tag ``eleNodes`` |listi| a list of two element nodes ``frnTag1``, ``frnTag2`` ``frnTag3`` |int| = tags associated with previously-defined FrictionModels at the three sliding interfaces ``vertMatTag`` |int| = Pre-defined material tag for COMPRESSION behavior of the bearing ``rotZMatTag`` ``rotXMatTag`` ``rotYMatTag`` |int| = Pre-defined material tags for rotational behavior about 3-axis, 1-axis and 2-axis, respectively. ``L1`` ``L2`` ``L3`` |float| = effective radii. Li = R_i - h_i (see Figure 1) ``d1`` ``d2`` ``d3`` |float| = displacement limits of pendulums (Figure 1). Displacement limit of the bearing is 2 ``d1`` + ``d2`` + ``d3`` + ``L1``. ``d3``/ ``L3`` - ``L1``. ``d2``/ ``L2`` ``W`` |float| = axial force used for the first trial of the first analysis step. ``uy`` |float| = lateral displacement where sliding of the bearing starts. Recommended value = 0.25 to 1 mm. A smaller value may cause convergence problem. ``kvt`` |float| = Tension stiffness k_vt of the bearing. ``minFv (>=0)`` |float| = minimum vertical compression force in the bearing used for computing the horizontal tangent stiffness matrix from the normalized tangent stiffness matrix of the element. ``minFv`` is substituted for the actual compressive force when it is less than ``minFv``, and prevents the element from using a negative stiffness matrix in the horizontal direction when uplift occurs. The vertical nodal force returned to nodes is always computed from ``kvc`` (or ``kvt``) and vertical deformation, and thus is not affected by ``minFv``. ``tol`` |float| = relative tolerance for checking the convergence of the element. Recommended value = 1.e-10 to 1.e-3. =============================================================== =========================================================================== .. seealso:: `Notes `_