Rack element with hinges - rackH
This element is a 3D beam element with thin-walled, open, cross-sections similarly to the rack element but with lumped plasticity at the element ends. The element is characterized by seven degrees of freedom per node, so as to correctly estimate both the displacements and the internal stresses, including warping displacements and bi-moment stresses, and to correctly predict the flexural-torsional and lateral-torsional buckling, derived by the coupling between flexure and torsion. Furthermore, the model allows to model inelastic behaviour through nonlinear springs at the two ends of the element. As a result, during the element definition, a response curve describing the moment-deformation relationship for each of the two rotational degrees of freedom of each element edge is required.
Currently, twenty nine response curves are selectable within the Element Class dialog box, whenever a link element type is selected.
- Linear symmetric curve - lin_sym
- Linear asymmetric curve - lin_asm
- Bilinear symmetric curve - bl_sym
- Bilinear asymmetric curve - bl_asm
- Bilinear kinematic hardening curve - bl_kin
- Trilinear symmetric curve - trl_sym
- Trilinear asymmetric curve - trl_asm
- Quadrilinear symmetric curve - quad_sym
- Quadrilinear asymmetric curve - quad_asm
- Pinched asymmetric curve - pinched_asm
- Modified Ibarra-Medina-Krawinkler Deterioration curve with Bilinear Hysteretic Response – MIMK_bilin
- Modified Ibarra-Medina-Krawinkler Deterioration Model with Peak-Oriented Hysteretic Response – MIMK_peak
- Modified Ibarra-Medina-Krawinkler Deterioration Model with Pinched Hysteretic Response – MIMK_Pinched
- Nonlinear elastic curve - nlin_el
- Plastic curve - plst
- Simplified bilinear Takeda curve - Takeda
- Asymmetric bilinear Takeda curve - Takeda_asm
- Ramberg Osgood curve - Ramberg Osgood
- Modified Richard-Abbott curve - Richard Abbott
- Soil-structure interaction curve - ssi_py
- Gap-hook curve - gap_hk
- Multi-linear curve - multi_lin
- Smooth curve - smooth
- Viscous Damper – vsc_dmp
- Bouc Wen Curve – Bouc_Wen
- Elastic – Perfectly plastic Gap Material - gap_elpl
- Impact response curve – pound_hz
- Self Centering Brace - scb
- Generic Hysteretic Curve – gen_hyst
In this element's dialog box it is also possible to define an element-specific damping, as opposed to the global damping described in here. To do so, users need simply to press the Damping button and then select the type of damping that better suits the element in question (users should refer to the Damping menu for a discussion on the different types of damping available and hints on which might the better options). Users are reminded also that damping defined at element level takes precedence over global damping, that is, the "globally-computed" damping matrix coefficients that are associated to the degrees-of-freedom of a given element will be replaced by coefficients that will have been calculated through the multiplication of the mass matrix of the element by a mass-proportional parameter, or through the multiplication of the element stiffness matrix by a stiffness-proportional parameter, or through the calculation of an element damping Rayleigh matrix.
Note: If Rayleigh damping is defined at element level, using varied coefficients from one element to the other, or with respect to those employed in the global damping settings, then non-classical Rayleigh damping is being modelled, classing Rayleigh damping requires uniform damping definition.
Local Axes and Output Notation
