# 4.13.5.29. KikuchiAikenLRB Material¶

uniaxialMaterial('KikuchiAikenLRB', matTag, type, ar, hr, gr, ap, tp, alph, beta, <'-T', temp>, <'-coKQ', rk, rq>, <'-coMSS', rs, rf>)

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 = $$\frac{1}{\sum_{i=0}^{n-1}\sin(\pi*i/n)^2}$$ and rf = $$\frac{1}{\sum_{i=0}{n-1}\sin(\pi*i/n)}$$, where n is the number of springs in the MSS. For example, when n=8, rs = 0.2500 and rf = 0.1989.