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Retrieval Model and Eigenvalue Analysis Data¤

This live script is written as a guided walkthrough for a post-processing workflow. It focuses on retrieving, organizing, and visualizing model or response data after an OpenSees analysis. Read the text cells first, then run each code cell in order so that the variables, model state, and recorded results are available for the later sections.

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clc; clear; close all;

Model Data¤

First, instantiate the OpenSeesMatlab interface class. This class provides native OpenSees commands, as well as additional visualization, pre/post-processing, and utility methods.

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opsMAT = OpenSeesMatlab();
ops = opsMAT.opensees;

For example, the tool property provides a function loadExamples to run some built-in models. Of course, you can run your own model; the built-in model is used here for demonstration purposes only.

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opsMAT.utils.loadExamples("Frame3D");
% or your model here

We can visualize the model using the plotModel function in the vis attribute.

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figure;
h = opsMAT.vis.plotModel();
Output
[OpenSeesMatlab] Model summary Nodes: 384 Beam elements: 930
figure_0.png

We can retrieve data from the current model, which returns a nested struct. You can view the data using MATLAB's workspace variables.

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modelData = opsMAT.post.getModelData();
disp(modelData)
Output
Nodes: [1x1 struct] Fixed: [1x1 struct] MPConstraint: [1x1 struct] Loads: [1x1 struct] Elements: [1x1 struct] NumNode: 384 NumElement: 930

Finally, we can print the information for each field.

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S = modelData;

stack = {{'S', S}};

while ~isempty(stack)
    item = stack{end};
    stack(end) = [];

    name = item{1};
    val  = item{2};

    if isstruct(val)
        fns = fieldnames(val);
        for i = numel(fns):-1:1
            f = fns{i};
            stack{end+1} = {sprintf('%s.%s', name, f), val.(f)};
        end
    else
        sz = strjoin(string(size(val)), 'x');
        fprintf('%s : %s\n', name, sz);
    end
end
Output
S.Nodes.Tags : 384x1 S.Nodes.Coords : 384x3 S.Nodes.Ndm : 384x1 S.Nodes.Ndf : 384x1 S.Nodes.UnusedTags : 0x1 S.Nodes.Bounds : 1x6 S.Nodes.MinBoundSize : 1x1 S.Nodes.MaxBoundSize : 1x1 S.Fixed.NodeTags : 24x1 S.Fixed.NodeIndex : 24x1 S.Fixed.Coords : 24x3 S.Fixed.Dofs : 24x6 S.MPConstraint.PairNodeTags : 0x2 S.MPConstraint.Cells : 0x3 S.MPConstraint.MidCoords : 0x3 S.MPConstraint.Dofs : 0x6 S.Loads.PatternTags : 0x1 S.Loads.Node.PatternNodeTags : 0x2 S.Loads.Node.Values : 0x3 S.Loads.Element.Beam.PatternElementTags : 0x2 S.Loads.Element.Beam.Values : 0x10 S.Loads.Element.Surface.PatternElementTags : 0x2 S.Loads.Element.Surface.Values : 0x0 S.Elements.Summary.Tags : 930x1 S.Elements.Summary.ClassTags : 930x1 S.Elements.Summary.CenterCoords : 930x3 S.Elements.Families.Truss.Tags : 0x1 S.Elements.Families.Truss.Cells : 0x3 S.Elements.Families.Beam.Tags : 930x1 S.Elements.Families.Beam.Cells : 930x3 S.Elements.Families.Beam.Midpoints : 930x3 S.Elements.Families.Beam.Lengths : 930x1 S.Elements.Families.Beam.XAxis : 930x3 S.Elements.Families.Beam.YAxis : 930x3 S.Elements.Families.Beam.ZAxis : 930x3 S.Elements.Families.Link.Tags : 0x1 S.Elements.Families.Link.Cells : 0x3 S.Elements.Families.Link.Midpoints : 0x3 S.Elements.Families.Link.Lengths : 0x1 S.Elements.Families.Link.XAxis : 0x3 S.Elements.Families.Link.YAxis : 0x3 S.Elements.Families.Link.ZAxis : 0x3 S.Elements.Families.Line.Tags : 930x1 S.Elements.Families.Line.Cells : 930x3 S.Elements.Families.Plane.Tags : 0x1 S.Elements.Families.Plane.Cells : 0x0 S.Elements.Families.Plane.CellTypes : 0x1 S.Elements.Families.Shell.Tags : 0x1 S.Elements.Families.Shell.Cells : 0x0 S.Elements.Families.Shell.CellTypes : 0x1 S.Elements.Families.Solid.Tags : 0x1 S.Elements.Families.Solid.Cells : 0x0 S.Elements.Families.Solid.CellTypes : 0x1 S.Elements.Families.Joint.Tags : 0x1 S.Elements.Families.Contact.Tags : 0x1 S.Elements.Families.Contact.Cells : 0x3 S.Elements.Families.Unstructured.Tags : 0x1 S.Elements.Families.Unstructured.Cells : 0x0 S.Elements.Families.Unstructured.CellTypes : 0x1 S.Elements.Classes.ElasticBeam3d.Cells : 930x3 S.Elements.Classes.ElasticBeam3d.CellTypes : 930x1 S.Elements.Classes.ElasticBeam3d.ElementTags : 930x1 S.NumNode : 1x1 S.NumElement : 1x1

Eigen Data¤

First, we need to save the eigenvalue analysis results data for future reuse.

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tag = 1;
opsMAT.post.saveEigenData(tag, 10, solver='-genBandArpack');
Output
[OpenSees] Using DomainModalProperties - Developed by: Massimo Petracca, Guido Camata, ASDEA Software Technology

Then, data is retrieved from the file, returning a nested structure that stores the various results of the eigenvalue analysis.

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eigenData = opsMAT.post.getEigenData(odbTag=tag);
disp(eigenData)
Output
EigenVectors: [1x1 struct] InterpolatedEigenVectors: [1x1 struct] ModalProps: [1x1 struct] ModelInfo: [1x1 struct] ModeTags: [10x1 double]

Using this data, we can visualize the first modal shapes.

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figure;
opsMAT.vis.plotEigen(6, eigenData);
axis off
figure_1.png
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S = eigenData;

stack = {{'S', S}};

while ~isempty(stack)
    item = stack{end};
    stack(end) = [];

    name = item{1};
    val  = item{2};

    if isstruct(val)
        fns = fieldnames(val);
        for i = numel(fns):-1:1
            f = fns{i};
            stack{end+1} = {sprintf('%s.%s', name, f), val.(f)};
        end
    else
        sz = strjoin(string(size(val)), 'x');
        fprintf('%s : %s\n', name, sz);
    end
end
Output
S.EigenVectors.data : 10x384x6 S.EigenVectors.nodeCoords : 384x3 S.EigenVectors.nodeNdf : 384x1 S.EigenVectors.nodeNdm : 384x1 S.EigenVectors.nodeTags : 384x1 S.InterpolatedEigenVectors.cellNodeTags : 930x2 S.InterpolatedEigenVectors.cells : 4650x3 S.InterpolatedEigenVectors.data : 10x5580x3 S.InterpolatedEigenVectors.eleTags : 930x1 S.InterpolatedEigenVectors.modeTags : 10x1 S.InterpolatedEigenVectors.nodeTags : 384x1 S.InterpolatedEigenVectors.nptsPerElement : 1x1 S.InterpolatedEigenVectors.pointID : 5580x1 S.InterpolatedEigenVectors.points : 5580x3 S.ModalProps.attrs.centerOfMass : 1x3 S.ModalProps.attrs.domainSize : 1x1 S.ModalProps.attrs.totalFreeMass : 1x6 S.ModalProps.attrs.totalMass : 1x6 S.ModalProps.raw.centerOfMass : 1x3 S.ModalProps.raw.domainSize : 1x1 S.ModalProps.raw.eigenFrequency : 1x10 S.ModalProps.raw.eigenLambda : 1x10 S.ModalProps.raw.eigenOmega : 1x10 S.ModalProps.raw.eigenPeriod : 1x10 S.ModalProps.raw.partiFactorMX : 1x10 S.ModalProps.raw.partiFactorMY : 1x10 S.ModalProps.raw.partiFactorMZ : 1x10 S.ModalProps.raw.partiFactorRMX : 1x10 S.ModalProps.raw.partiFactorRMY : 1x10 S.ModalProps.raw.partiFactorRMZ : 1x10 S.ModalProps.raw.partiMassMX : 1x10 S.ModalProps.raw.partiMassMY : 1x10 S.ModalProps.raw.partiMassMZ : 1x10 S.ModalProps.raw.partiMassRMX : 1x10 S.ModalProps.raw.partiMassRMY : 1x10 S.ModalProps.raw.partiMassRMZ : 1x10 S.ModalProps.raw.partiMassRatiosCumuMX : 1x10 S.ModalProps.raw.partiMassRatiosCumuMY : 1x10 S.ModalProps.raw.partiMassRatiosCumuMZ : 1x10 S.ModalProps.raw.partiMassRatiosCumuRMX : 1x10 S.ModalProps.raw.partiMassRatiosCumuRMY : 1x10 S.ModalProps.raw.partiMassRatiosCumuRMZ : 1x10 S.ModalProps.raw.partiMassRatiosMX : 1x10 S.ModalProps.raw.partiMassRatiosMY : 1x10 S.ModalProps.raw.partiMassRatiosMZ : 1x10 S.ModalProps.raw.partiMassRatiosRMX : 1x10 S.ModalProps.raw.partiMassRatiosRMY : 1x10 S.ModalProps.raw.partiMassRatiosRMZ : 1x10 S.ModalProps.raw.partiMassesCumuMX : 1x10 S.ModalProps.raw.partiMassesCumuMY : 1x10 S.ModalProps.raw.partiMassesCumuMZ : 1x10 S.ModalProps.raw.partiMassesCumuRMX : 1x10 S.ModalProps.raw.partiMassesCumuRMY : 1x10 S.ModalProps.raw.partiMassesCumuRMZ : 1x10 S.ModalProps.raw.totalFreeMass : 1x6 S.ModalProps.raw.totalMass : 1x6 S.ModalProps.data : 10x34 S.ModeTags : 10x1

Let's look at the period of each mode.

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S.ModalProps.raw.eigenPeriod
Output
ans = 1x10 2.2607 2.1196 1.9810 0.7388 0.6988 0.6564 0.4202 0.4051 0.3870 0.2951

Let's look at the cumulative participation mass ratio (%) in each direction.

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S.ModalProps.raw.partiMassRatiosCumuMX
Output
ans = 1x10 0.0000 80.7272 80.7272 80.7272 91.1228 91.1228 91.1228 94.5874 94.5874 94.5874 
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S.ModalProps.raw.partiMassRatiosCumuMY
Output
ans = 1x10 79.6341 79.6341 79.6341 90.9131 90.9131 90.9131 94.4481 94.4481 94.4481 96.2749 
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S.ModalProps.raw.partiMassRatiosCumuMZ
Output
ans = 1x10 1.0e-28 * 0.0000 0.0000 0.0000 0.0219 0.0277 0.0338 0.0384 0.0555 0.2074 0.2365 
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S.ModalProps.raw.partiMassRatiosCumuRMX
Output
ans = 1x10 19.1567 19.1567 19.1567 71.8213 71.8213 71.8213 78.3219 78.3219 78.3219 85.4282 
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S.ModalProps.raw.partiMassRatiosCumuRMY
Output
ans = 1x10 0.0000 16.7152 16.7152 16.7152 67.3875 67.3875 67.3875 72.9309 72.9309 72.9309 
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S.ModalProps.raw.partiMassRatiosCumuRMZ
Output
ans = 1x10 0.0000 0.0000 81.5449 81.5449 81.5449 91.1897 91.1897 91.1897 94.6036 94.6036