DisplacementControl Integrator

The DisplacementControl integrator is a static integration method that controls the displacement at a specific degree of freedom during analysis.

Description

This integrator is particularly suitable for:

Static analysis with prescribed displacement targets
Post-peak analysis in nonlinear structures
Cases where load-based control becomes unstable
Studies of structural behavior under specific displacement thresholds
Pushover analysis of structures

The DisplacementControl method applies load in a manner to achieve the target displacement increment at a specified node and degree of freedom.

Parameters

The DisplacementControl integrator requires the following parameters:

Parameter	Description	Default	Notes
node_tag	Tag of the controlling node	None	Required
dof	Degree of freedom at the node (1-ndf)	None	Required
incr	First displacement increment	None	Required
num_iter	Number of iterations desired	1	Optional
min_incr	Minimum step size allowed	incr	Optional, defaults to incr value
max_incr	Maximum step size allowed	incr	Optional, defaults to incr value

Usage Example

# Create a DisplacementControl integrator with basic parameters
integrator = fm.analysis.integrators.create_integrator("displacementcontrol",
                                                node_tag=3,
                                                dof=1,
                                                incr=0.01)

# Create a DisplacementControl integrator with custom step size limits
integrator = fm.analysis.integrators.create_integrator("displacementcontrol",
                                                node_tag=3,
                                                dof=1,
                                                incr=0.01,
                                                num_iter=5,
                                                min_incr=0.005,
                                                max_incr=0.02)