.. include:: sub.txt ======================== KikuchiAikenLRB Material ======================== .. function:: uniaxialMaterial('KikuchiAikenLRB', matTag, type, ar, hr, gr, ap, tp, alph, beta, <'-T', temp>, <'-coKQ', rk, rq>, <'-coMSS', rs, rf>) :noindex: This command is used to construct a uniaxial KikuchiAikenLRB material object. This material model produces nonlinear hysteretic curves of lead-rubber bearings. =================================== =========================================================================== ``matTag`` |int| integer tag identifying material ``type`` |int| rubber type (see note 1) ``ar`` |float| area of rubber [unit: m^2] ``hr`` |float| total thickness of rubber [unit: m] ``gr`` |float| shear modulus of rubber [unit: N/m^2] ``ap`` |float| area of lead plug [unit: m^2] ``tp`` |float| yield stress of lead plug [unit: N/m^2] ``alph`` |float| shear modulus of lead plug [unit: N/m^2] ``beta`` |float| ratio of initial stiffness to yielding stiffness ``temp`` |float| temperature [unit: °C] ``rk`` ``rq`` |float| reduction rate for yielding stiffness ( ``rk``) and force at zero displacement ( ``rq``) ``rs`` ``rf`` |float| reduction rate for stiffness ( ``rs``) and force ( ``rf``) (see note 3) =================================== =========================================================================== .. note:: 1) Following rubber types for ``type`` are available: * ``1`` lead-rubber bearing, up to 400% shear strain [Kikuchi et al., 2010 & 2012] 2) This material uses SI unit in calculation formula. Input arguments must be converted into [m], [m^2], [N/m^2]. 3) ``rs`` and ``rf`` are available if this material is applied to multipleShearSpring (MSS) element. Recommended values are ``rs`` = :math:`\frac{1}{\sum_{i=0}^{n-1}\sin(\pi*i/n)^2}` and ``rf`` = :math:`\frac{1}{\sum_{i=0}{n-1}\sin(\pi*i/n)}`, where n is the number of springs in the MSS. For example, when n=8, ``rs`` = 0.2500 and ``rf`` = 0.1989. .. seealso:: `Notes `_