Boundary Conditions in Dynamic Analysis of Earthquake
The "Earthquake" frame allows for setting either the fixed (kinematic) or absorbing (traction) boundary condition on the bottom boundary of the numerical model.
Fixed boundary condition:
Reflects the outgoing waves back into the model domain. This corresponds to the case when the model is truncated at the interface between a relatively soft soil layer and a stiff bedrock.
Absorbing boundary condition:
Transmits the outgoing wave through the model bottom boundary. Because such a wave will never return into the model, it corresponds to a dashpot, which damps this wave at this boundary. This condition is suitable whenever the model is truncated within a soil/rock layer. The material model of this layer should be elastic. The nonlinearity should be confined to top layers only.
Selection of the type of boundary conditions on the bottom boundary of the numerical model
Further details are available in the theoretical manual on our website.