repository·master·Indexed 41 days ago
https://github.com/zhuminjie/openseespydocDocumentation for OpenSeesPy, a Python 3 interpreter for the OpenSees finite element framework. It provides a comprehensive reference for Python commands, including model definition (ops.model), analysis configuration (constraints, numberer, system, test, algorithm, integrator), and specific element types like 20NodeBrick, AC3D8, and ASI3D8. The library is available for Linux, Windows, and Mac (ARM64).
OpenSeesPy provides a variety of output commands used to retrieve data from a simulation. These commands are non-destructive, meaning they do not change the internal state of the OpenSees model. They are categorized into several functional groups:
nodeAccel), coordinates (nodeCoord), displacement (nodeDisp), velocity (nodeVel), mass (nodeMass), and reactions (nodeReaction).eleForce), dynamical forces (eleDynamicalForce), and element responses (eleResponse).sectionForce), deformation (sectionDeformation), and stiffness (sectionStiff).getTime), system size (systemSize), version (version), and model structure (printModel).nodeDOFs, getConstrainedDOFs) and nodes (getNodeTags, getFixedNodes).numIter) and test norms (testNorm).recorder or record to log data during simulation.The OpenSeesPy documentation provides a comprehensive record of all Python commands available in the OpenSeesPy interpreter, along with usage examples. You can view the full documentation online at the ReadTheDocs site.
https://openseespydoc.readthedocs.io/en/latest/OpenSeesPy provides a specific set of commands for performing Fluid-Structure Interaction (FSI) analyses. These commands allow users to manage meshes, remeshing processes, and Particle Finite Element Method (PFEM) components including integrators, systems, tests, and analysis configurations.
Available FSI command categories include:
mesh and remesh commands for defining and updating the computational domain.pfemIntegrator, pfemSystem, pfemTest, and pfemAnalysis for managing the Particle Finite Element Method logic used in fluid-structure coupling.randomVariable.OpenSees provides a suite of commands specifically designed for performing sensitivity analysis. These commands allow you to manage parameters, compute gradients, and calculate the sensitivity of various structural responses (such as node displacement, velocity, acceleration, or section forces) with respect to model parameters.
Key functional areas include:
parameter, addToParameter, updateParameter, setParameter, getParamTags, and getParamValue allow you to define and manipulate the parameters used in sensitivity calculations.computeGradients and sensitivityAlgorithm to manage how sensitivities are mathematically derived.sensNodeDisp: Node displacement sensitivity.sensNodeVel: Node velocity sensitivity.sensNodeAccel: Node acceleration sensitivity.sensLambda: Sensitivity related to eigenvalues/eigenvectors.sensSectionForce: Section force sensitivity.sensNodePressure: Node pressure sensitivity.In OpenSees, a model (or domain) is an aggregation of various components that define the physical system being analyzed. To build a complete simulation, you must define a collection of the following entities:
SP_Constraint) and multi-point (mp_constraint) constraints.pattern), time series (timeSeries), and mass (mass).uniaxialMaterial), nD materials (ndMaterial), and cross-sectional definitions (section).geomTransf), beam integration (beamIntegration), and damping models (reyleigh).region), blocks (block), and friction models (frictionModel).The MVLEM (Multiple-Vertical-Line-Element-Model) element is used to simulate the flexure-dominated behavior of reinforced concrete (RC) walls in two dimensions.
c from the bottom of the wall element.c.c.c = 0.4 is recommended for the location of the center of rotation from the bottom node, based on experimental comparisons.Because the SSPbrickUP element uses equal-order interpolation for displacement and pressure, it does not inherently satisfy the inf-sup condition. To stabilize the element and allow for equal-order interpolation, you must provide a small spatial pressure field stabilization parameter alpha.
Calculate alpha using the following formula:
$$\alpha = h^2 / (4 * (K_s + (4/3) * G_s))$$
Where:
The bbarQuadUP element is a four-node plane-strain mixed volume/pressure element using a tri-linear isoparametric formulation. It is designed to simulate the dynamic response of solid-fluid fully coupled materials based on Biot's theory of porous media.
Each element node has 3 degrees-of-freedom (DOF):
u)p)In transient analysis, contact constraints can affect the stability of common time integration methods (like HHT or Newmark).
Recommendations:
gamma = 0.5 and beta = 0.25 is particularly prone to instability and is not recommended.TRBDF2 integrator is an effective method for numerically damping spurious high-frequency behavior caused by contact constraints.gamma and beta coefficients.Because the SSPquadUP element uses equal-order interpolation for displacement and pressure fields, it does not inherently satisfy the inf-sup condition. To prevent instability, a stabilizing parameter alpha must be provided.
alpha should be a small number and can be calculated using the following formula:
$$\alpha = 0.25 \cdot \frac{h^2}{den \cdot c^2}$$
Where: