Animation of dynamic analysis and mode shapes of a 2d Portal Frame

Example .py file can be downloaded here:

If you do not see the animation running, depending on Python environment, you will have to set a matplotlib backand which supports animation.

For example to see the matplotlib animations in the Spyder Python editor (which should be installed with the Anaconda platform), in the IPython console run %matplotlib qt. Then comment/uncomment one of the two animations.

  1import openseespy.opensees as ops
  2# import opensees as ops  # local compilation
  3import opsvis as opsv
  4
  5import numpy as np
  6import matplotlib.pyplot as plt
  7
  8# input_parameters = (3.8, 50., 100.)
  9# input_parameters = (53.5767, 50., 100.)
 10input_parameters = (20.8, 300., 8.)
 11# input_parameters = (70.0, 500., 2.)
 12
 13pf, sfac_a, tkt = input_parameters
 14
 15ops.wipe()
 16ops.model('basic', '-ndm', 2, '-ndf', 3)  # frame 2D
 17
 18colL, girL = 4., 6.
 19
 20Acol, Agir = 0.06, 0.06
 21IzCol, IzGir = 0.0002, 0.0002
 22
 23E = 3.2e10
 24rho = 2400.
 25muCol = rho * Acol
 26muGir = rho * Agir
 27massCol = ['-mass', muCol, '-cMass']
 28massGir = ['-mass', muGir, '-cMass']
 29
 30ops.node(0, 0.0, 0.0)
 31ops.node(1, 0.0, 2.0)
 32ops.node(2, 0.0, 4.0)
 33ops.node(3, 3.0, 4.0)
 34ops.node(4, 6.0, 4.0)
 35ops.node(5, 6.0, 2.0)
 36ops.node(6, 6.0, 0.0)
 37
 38ops.fix(0, 1, 1, 1)
 39ops.fix(6, 1, 1, 0)
 40
 41gTTag = 1
 42ops.geomTransf('Linear', gTTag)
 43
 44# 1st column
 45ops.element('elasticBeamColumn', 1, 0, 1, Acol, E, IzCol, gTTag, *massCol)
 46ops.element('elasticBeamColumn', 2, 1, 2, Acol, E, IzCol, gTTag, *massCol)
 47# girder
 48ops.element('elasticBeamColumn', 3, 2, 3, Agir, E, IzGir, gTTag, *massGir)
 49ops.element('elasticBeamColumn', 4, 3, 4, Agir, E, IzGir, gTTag, *massGir)
 50# 2nd column
 51ops.element('elasticBeamColumn', 5, 4, 5, Acol, E, IzCol, gTTag, *massCol)
 52ops.element('elasticBeamColumn', 6, 5, 6, Acol, E, IzCol, gTTag, *massCol)
 53
 54t0 = 0.
 55tk = 1.
 56Tp = 1/pf
 57P0 = 15000.
 58dt = 0.002
 59n_steps = int((tk-t0)/dt)
 60
 61tsTag = 1
 62ops.timeSeries('Trig', tsTag, t0, tk, Tp, '-factor', P0)
 63
 64patTag = 1
 65ops.pattern('Plain', patTag, tsTag)
 66ops.load(1, 1., 0., 0.)
 67
 68ops.constraints('Transformation')
 69ops.numberer('RCM')
 70ops.test('NormDispIncr', 1.0e-6, 10, 1)
 71ops.algorithm('Linear')
 72ops.system('ProfileSPD')
 73ops.integrator('Newmark', 0.5, 0.25)
 74ops.analysis('Transient')
 75
 76el_tags = ops.getEleTags()
 77
 78nels = len(el_tags)
 79
 80Eds = np.zeros((n_steps, nels, 6))
 81timeV = np.zeros(n_steps)
 82
 83# transient analysis loop and collecting the data
 84for step in range(n_steps):
 85    ops.analyze(1, dt)
 86    timeV[step] = ops.getTime()
 87    # collect disp for element nodes
 88    for el_i, ele_tag in enumerate(el_tags):
 89        nd1, nd2 = ops.eleNodes(ele_tag)
 90        Eds[step, el_i, :] = [ops.nodeDisp(nd1)[0],
 91                              ops.nodeDisp(nd1)[1],
 92                              ops.nodeDisp(nd1)[2],
 93                              ops.nodeDisp(nd2)[0],
 94                              ops.nodeDisp(nd2)[1],
 95                              ops.nodeDisp(nd2)[2]]
 96
 97# 1. animate the deformated shape
 98anim = opsv.anim_defo(Eds, timeV, sfac_a, interpFlag=1, xlim=[-1, 7],
 99                      ylim=[-1, 5], fig_wi_he=(30., 22.))
100
101plt.show()
102
103# 2. after closing the window, animate the specified mode shape
104eigVals = ops.eigen(5)
105
106modeNo = 2  # specify which mode to animate
107f_modeNo = np.sqrt(eigVals[modeNo-1])/(2*np.pi)  # i-th natural frequency
108
109anim = opsv.anim_mode(modeNo, interpFlag=1, xlim=[-1, 7], ylim=[-1, 5],
110                      fig_wi_he=(30., 22.))
111plt.title(f'Mode {modeNo}, f_{modeNo}: {f_modeNo:.3f} Hz')
112
113plt.show()