Gambarotta Lagomarsino model - eesd-epfl/OpenSees GitHub Wiki
The shear model implemented in the macroelement in Penna et al. (2014), deriving from an integration along the section of the interface model proposed in Gambarotta & Lagomarsino (1988), is implemenrted here without further modifications. Details on the implementation are given in the two references. Additionally, the consistent algorthmic tangent matrix was derived and implemented, to ensure quadratic convergence when implicit methods are applied.
The maximum shear capacity of the Gambarotta Lagomarsino is defined by a Mohr-Coulomb criterion (with N positive in compression), applied on the gross section, as:
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Nonlinearity of the response begins when the frictional capacity is exceeded. The cohesive contribution undergoes progressive damage, controlled by a damage variable α; (which can be exported). The maximum force capacity is reached for α=1, and for a displacement smax controlled by a material parameter Gc. The postpeak response, in which the cohesive contribution is progressively lost, is controlled by a second parameter β. The shape of hysteretic cycles, and therefore the dissipation described by the model, depends by the proportion between the cohesive and the frictional contribution. As for all shear models, complete or partial loss of the lateral load bearing capacity can be controlled by the drift criterion attached to the element.
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