github_edit: False

SeismicDisplacement Syntax

The input file syntax for SeismicDisplacement with the the [BCs] block provides syntax for creating the correct PresetDisplacement boundary conditions for each direction components specified.

If the ground excitation was measured at a depth within the soil by placing an accelerometer at that location, then it is termed as a within-soil input. This time history contains the wave that was generated by the earthquake (incoming wave) and the wave that is reflected off the free surface. This ground excitation is applied as a prescribed displacement boundary condition. The input_function in this case should be the displacement time histories.

Example Usage

[BCs<<<{"href": "../index.html"}>>>]
  [./SeismicDisplacement<<<{"href": "index.html"}>>>]
    [./top_x]
      displacements<<<{"description": "The nonlinear displacement variables for the problem."}>>> = 'disp_x disp_y'
      velocities<<<{"description": "The vector of velocity variables names. The input velocities can be obtained from this variable. The size of this vector must be same size as input_component."}>>> = 'vel_x vel_y'
      accelerations<<<{"description": "The vector of acceleration variables that are coupled to displacements. The size of this vector should be same as displacements."}>>> = 'accel_x accel_y'
      input_components<<<{"description": "The directions in which the input ground motions are applied."}>>> = '0 1'
      input_functions<<<{"description": "The vector of function names that describes the input ground motions. Must be same size as input_component."}>>> = 'x_disp y_disp' #input displacements
      boundary<<<{"description": "The list of boundary IDs from the mesh where this boundary condition will be applied."}>>> = bottom
      beta<<<{"description": "The beta parameter for newmark time integration."}>>> = 0.4225
    [../]
  [../]
[]

Input Parameters

accelerationsThe vector of acceleration variables that are coupled to displacements. The size of this vector should be same as displacements.
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The vector of acceleration variables that are coupled to displacements. The size of this vector should be same as displacements.
boundaryThe list of boundary IDs from the mesh where this boundary condition will be applied.
C++ Type:std::vector<BoundaryName>
Controllable:No
Description:The list of boundary IDs from the mesh where this boundary condition will be applied.
displacementsThe nonlinear displacement variables for the problem.
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The nonlinear displacement variables for the problem.
input_componentsThe directions in which the input ground motions are applied.
C++ Type:std::vector<unsigned int>
Controllable:No
Description:The directions in which the input ground motions are applied.
input_functionsThe vector of function names that describes the input ground motions. Must be same size as input_component.
C++ Type:std::vector<FunctionName>
Unit:(no unit assumed)
Controllable:No
Description:The vector of function names that describes the input ground motions. Must be same size as input_component.
velocitiesThe vector of velocity variables names. The input velocities can be obtained from this variable. The size of this vector must be same size as input_component.
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The vector of velocity variables names. The input velocities can be obtained from this variable. The size of this vector must be same size as input_component.

Required Parameters

active__all__ If specified only the blocks named will be visited and made active
Default:__all__
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified only the blocks named will be visited and made active
beta0The beta parameter for newmark time integration.
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The beta parameter for newmark time integration.
inactiveIf specified blocks matching these identifiers will be skipped.
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified blocks matching these identifiers will be skipped.

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.

Advanced Parameters

(test/tests/bcs/seismic_displacement/seismic_displacement.i)

# Test for within soil seismic input. Test for outcrop seismic input is
# with non reflecting boundary condition

# This test consists of one brick element.

# A sawtooth displacement history is applied as seismic input to the bottom surface.

# Result: The result at the bottom should be same as the input displacement.

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 1
  ny = 1
  xmin = 0.0
  xmax = 1.0
  ymin = 0.0
  ymax = 1.0
[]

[Variables]
  [./disp_x]
  [../]
  [./disp_y]
  [../]
[]

[AuxVariables]
  [./vel_x]
  [../]
  [./accel_x]
  [../]
  [./vel_y]
  [../]
  [./accel_y]
  [../]
  [./layer]
    order = CONSTANT
    family = MONOMIAL
  [../]
[]

[ICs]
  [./layer_ic]
    type = FunctionIC
    variable = layer
    function = layer_y
  [../]
[]

[Kernels]
  [./DynamicTensorMechanics]
    displacements = 'disp_x disp_y'
    hht_alpha = -0.3
  [../]
  [./inertia_x]
    type = InertialForce
    variable = disp_x
    velocity = vel_x
    acceleration = accel_x
    beta = 0.4225
    gamma = 0.8
  [../]
  [./inertia_y]
    type = InertialForce
    variable = disp_y
    velocity = vel_y
    acceleration = accel_y
    beta = 0.4225
    gamma = 0.8
  [../]
[]

[AuxKernels]
  [./accel_x]
    type = NewmarkAccelAux
    variable = accel_x
    displacement = disp_x
    velocity = vel_x
    beta = 0.4225
    execute_on = timestep_end
  [../]
  [./vel_x]
    type = NewmarkVelAux
    variable = vel_x
    acceleration = accel_x
    gamma = 0.8
    execute_on = timestep_end
  [../]
  [./accel_y]
    type = NewmarkAccelAux
    variable = accel_y
    displacement = disp_y
    velocity = vel_y
    beta = 0.4225
    execute_on = timestep_end
  [../]
  [./vel_y]
    type = NewmarkVelAux
    variable = vel_y
    acceleration = accel_y
    gamma = 0.8
    execute_on = timestep_end
  [../]
[]


[BCs]
  [./SeismicDisplacement]
    [./top_x]
      displacements = 'disp_x disp_y'
      velocities = 'vel_x vel_y'
      accelerations = 'accel_x accel_y'
      input_components = '0 1'
      input_functions = 'x_disp y_disp' #input displacements
      boundary = bottom
      beta = 0.4225
    [../]
  [../]
[]

[Materials]
  [./Elasticity_tensor_1]
    type = ComputeIsotropicElasticityTensorSoil
    block = 0
    layer_variable = layer
    layer_ids = '10'
    shear_modulus = '71.42857'
    poissons_ratio = '0.4'
    density = '1.0'
  [../]

  [./strain_1]
    type = ComputeSmallStrain
    block = 0
    displacements = 'disp_x disp_y'
  [../]

  [./stress_1]
    type = ComputeLinearElasticStress
    block = 0
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'
  start_time = 0
  end_time = 2.0
  l_tol = 1e-12
  nl_abs_tol = 1e-15
  nl_rel_tol = 1e-12
  dt = 0.01
  timestep_tolerance = 1e-12
[]

[Functions]
  [./x_disp]
    type = PiecewiseLinear
    x = '0.0 0.25 0.5 0.75 1.0 1.25 1.5 2.0 3.0'
    y = '0.0 0.0  0.5 0.0 -0.5 0.0  0.0 0.0 0.0'
  [../]
  [./y_disp]
    type = PiecewiseLinear
    x = '0.0 0.25 0.5 0.75 1.0 1.25 1.5 2.0 3.0'
    y = '0.0 0.0  0.5 0.0 -0.5 0.0  0.0 0.0 0.0'
  [../]
  [./layer_y]
    type = ConstantFunction
    value = 10
  [../]
[]

[Postprocessors]
  [./_dt]
    type = TimestepSize
  [../]
  [./disp_1]
    type = NodalVariableValue
    nodeid = 0
    variable = disp_x
  [../]
  [./disp_2]
    type = NodalVariableValue
    nodeid = 0
    variable = disp_y
  [../]
[]

[Outputs]
  exodus = true
  csv = true
  print_linear_residuals = true
  perf_graph = true
[]

Example Usage
Input Parameters

Usage

Development

Demonstration