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)


  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.

See also