Shear response - eesd-epfl/OpenSees GitHub Wiki

The material model implmented for shear is a damage model in which the sections is divided into two parts, on damaged, that can carry only frictional forces and can develop plastic strains, and one that remains undamaged. The splitting of the section in the two portions is rules by a damage evolution law.

<\p>

The material model does not aim at providing the modelling of the local response, it rather describes phenomenologically the shear response of a masonry wall. The damage law, therefore, was defined in order to obtain the desired force envelope. The law is depends on the the parameters c and μ₀, that define the force capacity through a Mohr-Coulomb friction criterion:

<\p>

Where N is the axial load acting at midheight (considered here positive in compression). The parameter G_c controls the prepeak stiffness reduction after nonlinearity is attained (similarly to [Penna et al., 2014](https://onlinelibrary.wiley.com/doi/full/10.1002/eqe.2335)). The post-peak behaviour is linearly softening, with a strength loss of ξV_max at the drift fixed by s_ξ. It is postulated that the cohesive strength contribution as well as a part of the frictional contribution can undergo damage. The imposed damage law depends on a damage variable x, that can be exported, which is equal to 1 at peak force. After complete damage evolution, a residual strength capacity V_res is maintained.

<\p>

Complete or partial loss of the lateral load bearing capacity can be controlled by a drift criterion, potentially dependent on the axial load ratio and the shear span, to be attached to the element. The parameter μ_R controls the residual force capacity and, more importantly, the shape of the hysteresis loops, which become more “fat” when the residual friction increases.

<\p>

Details on the shear model formulation, as well as on the flexural model are presented in the paper, to which the reader is referred.

to Gambarotta-Lagomarsino model / back to standard element definition / home