Example #1
0
def RunIterations2(GRS, Fz, printOn):

    ops.timeSeries('Linear', 1)
    ops.pattern('Plain', 1, 1)
    for i in range(GRS.nbnBns):
        ops.load(int(100 + GRS.nbn[i]), 0., 0., Fz * un.kN, 0., 0., 0.)
    GRS.GetTopNode()
    # ops.load(int(100+GRS.maxNsID), 0., 0., Fz * kN, 0., 0., 0.)  # mid-point

    # create SOE
    ops.system('UmfPack')
    # create DOF number
    ops.numberer('RCM')
    # create constraint handler
    ops.constraints('Transformation')
    # create integrator
    ops.integrator("LoadControl", 1.0 / GRS.Steps)
    # create algorithm
    ops.algorithm("Newton")
    # create test
    ops.test('EnergyIncr', 1.e-10, 100)

    ops.analysis('Static')

    NDisp = np.zeros([GRS.Steps + 1, GRS.nbNsAll, 3])
    # EDisp = np.zeros([GRS.Steps + 1, GRS.nbElAll, 6])
    EForce = np.zeros([GRS.Steps + 1, GRS.nbElAll, 12])
    reI = 0

    reI = 0
    lefutott = 1
    for i in range(1, GRS.Steps + 1):
        hiba = ops.analyze(1)
        if hiba == 0:
            if i == 1:
                if printOn: print('analysis step 1 completed successfully')
            for j in range(GRS.nbNsAll):
                NDisp[i, j, 0] = -ops.nodeDisp(int(j + 100),
                                               1) / un.mm  # mm displacement
                NDisp[i, j, 1] = -ops.nodeDisp(int(j + 100),
                                               2) / un.mm  # mm displacement
                NDisp[i, j, 2] = -ops.nodeDisp(int(j + 100),
                                               3) / un.mm  # mm displacement
            for j in range(GRS.nbElAll):
                EForce[i, j] = ops.eleResponse(int(j + 1000), 'localForce')
                # EDisp[i, j] = ops.eleResponse(int(j + 1000), 'basicDeformation')
        else:
            lefutott = 0
            reI = i
            if reI == 1:
                if printOn: print('analysis failed to converge in step ', i)
            break

    return lefutott, NDisp, EForce, reI
Example #2
0
def test_recorder_time_step_can_handle_fp_precision():
    import tempfile
    opy.model('basic', '-ndm', 2, '-ndf', 3)
    opy.node(1, 0.0, 0.0)
    opy.node(2, 0.0, 5.0)
    opy.fix(2, 0, 1, 0)
    opy.fix(1, 1, 1, 1)
    opy.equalDOF(2, 1, 2)
    opy.mass(2, 1.0, 0.0, 0.0)
    opy.geomTransf('Linear', 1, '-jntOffset')
    opy.element('elasticBeamColumn', 1, 1, 2, 1.0, 1e+06, 0.00164493, 1)
    opy.timeSeries('Path', 1, '-dt', 0.1, '-values', 0.0, -0.001, 0.001,
                   -0.015, 0.033, 0.105, 0.18)
    opy.pattern('UniformExcitation', 1, 1, '-accel', 1)
    opy.rayleigh(0.0, 0.0159155, 0.0, 0.0)
    opy.wipeAnalysis()
    opy.algorithm('Newton')
    opy.system('SparseSYM')
    opy.numberer('RCM')
    opy.constraints('Transformation')
    opy.integrator('Newmark', 0.5, 0.25)
    opy.analysis('Transient')
    opy.test('EnergyIncr', 1e-07, 10, 0, 2)
    node_rec_ffp = tempfile.NamedTemporaryFile(delete=False).name
    ele_rec_ffp = tempfile.NamedTemporaryFile(delete=False).name
    rdt = 0.01
    adt = 0.001
    opy.recorder('Node', '-file', node_rec_ffp, '-precision', 16, '-dT', rdt,
                 '-rTolDt', 0.00001, '-time', '-node', 1, '-dof', 1, 'accel')
    opy.recorder('Element', '-file', ele_rec_ffp, '-precision', 16, '-dT', rdt,
                 '-rTolDt', 0.00001, '-time', '-ele', 1, 'force')

    opy.record()
    for i in range(1100):
        opy.analyze(1, adt)
        opy.getTime()
    opy.wipe()

    a = open(node_rec_ffp).read().splitlines()
    for i in range(len(a) - 1):
        dt = float(a[i + 1].split()[0]) - float(a[i].split()[0])
        assert abs(dt - 0.01) < adt * 0.1, (i, dt)
    a = open(ele_rec_ffp).read().splitlines()
    for i in range(len(a) - 1):
        dt = float(a[i + 1].split()[0]) - float(a[i].split()[0])
        assert abs(dt - 0.01) < adt * 0.1, (i, dt)
Example #3
0
# create DOF number
op.numberer('RCM')
# create constraint handler
alpha = 1e18
op.constraints('Penalty', alpha, alpha)
# create integrator
gamma = 0.6
beta = 0.3
op.integrator('Newmark', gamma, beta)
# create algorithm
op.algorithm('Newton')
# create test
tol = 1.0E-8
Iter = 25
pFlag = 0
op.test('NormDispIncr', tol, Iter, pFlag)
# create analysis object
op.analysis('VariableTransient')
# perform the analysis
dtMin = dt / 100
#Minimum time steps. (required for VariableTransient analysis)
dtMax = dt / 10
#Maximum time steps (required for VariableTransient analysis)
Jd = 1000
#Number of iterations user would like performed at each step. The variable transient analysis will change current time step if last analysis step took more or less iterations than this to converge (required for VariableTransient analysis)
op.analyze(numIncr, dt, dtMin, dtMax, Jd)
op.wipe()

#################################################################
# Plot the results
#################################################################
Example #4
0
# ----------------------------
# Start of analysis generation
# ----------------------------

# create the system of equation
ops.system("UmfPack")

# create the DOF numberer
ops.numberer("Plain")

# create the constraint handler
ops.constraints("Transformation")

# create the convergence test
ops.test("EnergyIncr", 1.0E-8, 20)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the integration scheme, the Newmark with gamma=0.5 and beta=0.25
ops.integrator("Newmark", 0.5, 0.25) 

# create the analysis object 
ops.analysis("Transient")

# --------------------------
# End of analysis generation
# --------------------------

Example #5
0
#---ANALYSIS PARAMETERS
# Newmark parameters
gamma = 0.5
beta = 0.25

#-----------------------------------------------------------------------------------------
#  9. GRAVITY ANALYSIS
#-----------------------------------------------------------------------------------------
# update materials to ensure elastic behavior
op.updateMaterialStage('-material', 1, '-stage', 0)
op.updateMaterialStage('-material', 2, '-stage', 0)
op.updateMaterialStage('-material', 3, '-stage', 0)

op.constraints('Penalty', 1.0E14, 1.0E14)
op.test('NormDispIncr', 1e-4, 35, 1)
op.algorithm('KrylovNewton')
op.numberer('RCM')
op.system('ProfileSPD')
op.integrator('Newmark', gamma, beta)
op.analysis('Transient')

startT = tt.time()
op.analyze(10, 5.0E2)
print('Finished with elastic gravity analysis...')

# update material to consider elastoplastic behavior
op.updateMaterialStage('-material', 1, '-stage', 1)
op.updateMaterialStage('-material', 2, '-stage', 1)
op.updateMaterialStage('-material', 3, '-stage', 1)
Example #6
0
# ----------------------- 
# End of model generation
# -----------------------


# ------------------------
# Start of static analysis
# ------------------------

# Load control with variable load steps
#                            init  Jd  min  max
ops.integrator("LoadControl", 1.0, 1, 1.0, 10.0)

# Convergence test
#                  tolerance maxIter displayCode
ops.test("EnergyIncr", 1.0E-10, 20, 0)

# Solution algorithm
ops.algorithm("Newton")

# DOF numberer
ops.numberer("RCM")

# Cosntraint handler
ops.constraints("Plain") 

# System of equations solver
ops.system("SparseGeneral", "-piv")
#ops.system("ProfileSPD")

# Analysis for gravity load
Example #7
0
# --------------------------------------------------
# Start of analysis generation for gravity analysis
# --------------------------------------------------

# create the system of equation
ops.system("BandGeneral")

# create the DOF numberer, the reverse Cuthill-McKee algorithm
ops.numberer("RCM")

# create the constraint handler, a Plain handler is used as h**o constraints
ops.constraints("Plain")

# Create the convergence test, the norm of the residual with a tolerance of 
# 1e-12 and a max number of iterations of 10
ops.test("NormDispIncr", 1.0E-8, 10, 0)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the integration scheme, the LoadControl scheme using steps of 0.1
ops.integrator("LoadControl", 0.1)

# create the analysis object 
ops.analysis("Static")

# ------------------------------------------------
# End of analysis generation for gravity analysis
# ------------------------------------------------

Example #8
0
# ----------------------------
# Start of analysis generation
# ----------------------------

# create the system of equation
ops.system("UmfPack")

# create the DOF numberer
ops.numberer("Plain")

# create the constraint handler
ops.constraints("Transformation")

# create the convergence test
ops.test("EnergyIncr", 1.0E-8, 20)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the integration scheme, the Newmark with gamma=0.5 and beta=0.25
ops.integrator("Newmark", 0.5, 0.25)

# create the analysis object
ops.analysis("Transient")

# --------------------------
# End of analysis generation
# --------------------------

# ----------------------------
Example #9
0
# ------------------------------
# Start of analysis generation
# ------------------------------

# create the system of equation
ops.system("BandGeneral")

# create the DOF numberer, the reverse Cuthill-McKee algorithm
ops.numberer("RCM")

# create the constraint handler, a Plain handler is used as h**o constraints
ops.constraints("Plain")

# Create the convergence test, the norm of the residual with a tolerance of
# 1e-12 and a max number of iterations of 10
ops.test("NormDispIncr", 1.0E-12, 10, 3)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the integration scheme, the LoadControl scheme using steps of 0.1
ops.integrator("LoadControl", 0.1)

# create the analysis object
ops.analysis("Static")

# ------------------------------
# End of analysis generation
# ------------------------------

# ------------------------------
Example #10
0
loadValues = [3500.0, 0.0, 0.0, 0.0, 0.0, 0.0]
op.timeSeries('Path', 1, '-values', *values, '-time', *time, '-factor', 1.0)

op.pattern('Plain', 10, 1)
op.load(nodeTag, *loadValues)

print("Finished creating loading object...")

#----------------------------------------------------------
#  create the analysis
#----------------------------------------------------------
op.integrator('LoadControl', 0.05)
op.numberer('RCM')
op.system('SparseGeneral')
op.constraints('Transformation')
op.test('NormDispIncr', 1e-5, 20, 1)
op.algorithm('Newton')
op.analysis('Static')

print("Starting Load Application...")
op.analyze(201)

print("Load Application finished...")
#print("Loading Analysis execution time: [expr $endT-$startT] seconds.")

#op.wipe

op.reactions()
Nodereactions = dict()
Nodedisplacements = dict()
for i in range(201,nodeTag+1):
Example #11
0
def RunIterations(GRS, Fz, printOn):
    ops.timeSeries('Linear', 1)
    ops.pattern('Plain', 1, 1)
    loadA = np.linspace(0, -Fz, GRS.Steps + 1)  # kN
    for i in range(GRS.nbnBns):
        if GRS.LoadType == 0 \
                or (GRS.GeomType in {0, 1, 2} and GRS.LoadType == 1 and GRS.nsAll.x[GRS.nbn[i]] <= 0) \
                or (GRS.GeomType in {0, 1, 2} and GRS.LoadType == 2 and GRS.nsAll.y[GRS.nbn[i]] <= 0) \
                or (GRS.GeomType in {4} and GRS.LoadType == 1 and GRS.nsAll.x[GRS.nbn[i]] <= GRS.span / 2) \
                or (GRS.GeomType in {4} and GRS.LoadType == 2 and GRS.nsAll.y[GRS.nbn[i]] <= GRS.span / 2):
            ops.load(int(100 + GRS.nbn[i]), 0., 0., Fz * un.kN, 0., 0., 0.)
    GRS.GetTopNode()
    # ops.load(int(100+GRS.maxNsID), 0., 0., Fz * kN, 0., 0., 0.)  # mid-point

    # create SOE
    ops.system('UmfPack')
    # create DOF number
    ops.numberer('RCM')
    # create constraint handler
    ops.constraints('Transformation')
    # create test
    ops.test('EnergyIncr', 1.e-12, 10)
    # create algorithm
    ops.algorithm("Newton")

    NDisp = np.zeros([GRS.Steps + 1, GRS.nbNsAll, 3])
    # EDisp = np.zeros([GRS.Steps + 1, GRS.nbElAll, 6])
    EForce = np.zeros([GRS.Steps + 1, GRS.nbElAll, 12])
    reI=0

    reI = 0
    lefutott = 1
    i=0
    load = 0
    stepSize = 1.0 / GRS.Steps
    ops.integrator("LoadControl", stepSize)
    ops.analysis('Static')
    while ((-stepSize*Fz > GRS.MinStepSize) and (i<GRS.Steps)):
        hiba = ops.analyze(1)
        if hiba == 0:
            load += -stepSize * Fz
            i += 1
            loadA[i] = load
            if i == 1:
                if printOn: print('analysis step 1 completed successfully')
            for j in range(GRS.nbNsAll):
                NDisp[i, j, 0] = - ops.nodeDisp(int(j + 100), 1) / un.mm  # mm displacement
                NDisp[i, j, 1] = - ops.nodeDisp(int(j + 100), 2) / un.mm  # mm displacement
                NDisp[i, j, 2] = - ops.nodeDisp(int(j + 100), 3) / un.mm  # mm displacement
            for j in range(GRS.nbElAll):
                EForce[i, j] = ops.eleResponse(int(j+1000), 'localForce')
                # EDisp[i, j] = ops.eleResponse(int(j + 1000), 'basicDeformation')
        else:
            stepSize = stepSize/2
            if printOn: print('analysis failed to converge in step ', i)
            ops.integrator("LoadControl", stepSize)
            lefutott = 0
            reI = i

    if i == GRS.Steps:
        if reI == 1:
            if printOn: print('analysis failed to converge')

    return lefutott, NDisp, EForce, loadA, reI
Example #12
0
# --------------------------------------------------
# Start of analysis generation for gravity analysis
# --------------------------------------------------

# create the system of equation
ops.system("BandGeneral")

# create the DOF numberer, the reverse Cuthill-McKee algorithm
ops.numberer("RCM")

# create the constraint handler, a Plain handler is used as h**o constraints
ops.constraints("Plain")

# Create the convergence test, the norm of the residual with a tolerance of
# 1e-12 and a max number of iterations of 10
ops.test("NormDispIncr", 1.0E-8, 10, 0)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the integration scheme, the LoadControl scheme using steps of 0.1
ops.integrator("LoadControl", 0.1)

# create the analysis object
ops.analysis("Static")

# ------------------------------------------------
# End of analysis generation for gravity analysis
# ------------------------------------------------

# ------------------------------
Example #13
0
def test_recorder_time_step_is_stable():
    opy.model('basic', '-ndm', 2, '-ndf', 2)
    opy.loadConst('-time', 1e+13)
    opy.node(1, 0.0, 0.0)
    opy.node(2, 0.5, 0.0)
    opy.node(3, 0.0, -0.5)
    opy.node(4, 0.5, -0.5)
    opy.equalDOF(3, 4, 1, 2)
    opy.node(5, 0.0, -1.0)
    opy.node(6, 0.5, -1.0)
    opy.equalDOF(5, 6, 1, 2)
    opy.node(7, 0.0, -1.5)
    opy.node(8, 0.5, -1.5)
    opy.equalDOF(7, 8, 1, 2)
    opy.node(9, 0.0, -2.0)
    opy.node(10, 0.5, -2.0)
    opy.equalDOF(9, 10, 1, 2)
    opy.node(11, 0.0, -2.5)
    opy.node(12, 0.5, -2.5)
    opy.equalDOF(11, 12, 1, 2)
    opy.node(13, 0.0, -3.0)
    opy.node(14, 0.5, -3.0)
    opy.equalDOF(13, 14, 1, 2)
    opy.fix(13, 0, 1)
    opy.fix(14, 0, 1)
    opy.node(15, 0.0, -3.0)
    opy.node(16, 0.0, -3.0)
    opy.fix(15, 1, 1)
    opy.fix(16, 0, 1)
    opy.equalDOF(13, 14, 1)
    opy.equalDOF(13, 16, 1)
    opy.nDMaterial('ElasticIsotropic', 1, 212500.0, 0.0, 1.7)
    opy.element('SSPquad', 1, 3, 4, 2, 1, 1, 'PlaneStrain', 1.0, 0.0, 16.677)
    opy.element('SSPquad', 2, 5, 6, 4, 3, 1, 'PlaneStrain', 1.0, 0.0, 16.677)
    opy.element('SSPquad', 3, 7, 8, 6, 5, 1, 'PlaneStrain', 1.0, 0.0, 16.677)
    opy.element('SSPquad', 4, 9, 10, 8, 7, 1, 'PlaneStrain', 1.0, 0.0, 16.677)
    opy.element('SSPquad', 5, 11, 12, 10, 9, 1, 'PlaneStrain', 1.0, 0.0,
                16.677)
    opy.element('SSPquad', 6, 13, 14, 12, 11, 1, 'PlaneStrain', 1.0, 0.0,
                16.677)
    opy.uniaxialMaterial('Viscous', 2, 212.5, 1.0)
    opy.element('zeroLength', 7, 15, 16, '-mat', 2, '-dir', 1)
    opy.constraints('Transformation')
    opy.test('NormDispIncr', 0.0001, 30, 0, 2)
    opy.algorithm('Newton', False, False, False)
    opy.numberer('RCM')
    opy.system('ProfileSPD')
    opy.integrator('Newmark', 0.5, 0.25)
    opy.analysis('Transient')
    opy.analyze(40, 1.0)
    opy.analyze(50, 0.5)
    opy.setTime(1.0e3)
    opy.wipeAnalysis()
    opy.recorder('Node', '-file', 'time_0_01.txt', '-precision', 16, '-dT',
                 0.01, '-rTolDt', 0.00001, '-time', '-node', 1, '-dof', 1,
                 'accel')
    opy.recorder('Element', '-file', 'etime_0_01.txt', '-precision', 16, '-dT',
                 0.01, '-rTolDt', 0.00001, '-time', '-ele', 1, 2, 'stress')
    opy.recorder('EnvelopeNode', '-file', 'entime_0_01.txt', '-precision', 16,
                 '-dT', 0.01, '-time', '-node', 1, '-dof', 1, 'accel')
    # opy.recorder('Drift', '-file', 'dtime_0_01.txt', '-precision', 16, '-dT', 0.01, '-time',
    #              '-iNode', 1, '-jNode', 2, '-dof', 1, '-perpDirn', 2)
    opy.timeSeries('Path', 1, '-dt', 0.01, '-values', -0.0, -0.0, -0.0, -0.0,
                   -0.0, -0.0, -0.0, -0.0, -7.51325e-05)
    opy.pattern('Plain', 1, 1)
    opy.load(13, 1.0, 0.0)
    opy.algorithm('Newton', False, False, False)
    opy.system('SparseGeneral')
    opy.numberer('RCM')
    opy.constraints('Transformation')
    opy.integrator('Newmark', 0.5, 0.25)
    opy.rayleigh(0.17952, 0.000909457, 0.0, 0.0)
    opy.analysis('Transient')
    opy.test('EnergyIncr', 1e-07, 10, 0, 2)
    opy.record()
    opy.analyze(1, 0.001)
    for i in range(1100):
        print(i)
        opy.analyze(1, 0.001)
        cur_time = opy.getTime()
    opy.wipe()

    a = open('time_0_01.txt').read().splitlines()
    for i in range(len(a) - 1):
        dt = float(a[i + 1].split()[0]) - float(a[i].split()[0])
        assert abs(dt - 0.01) < 0.0001, (i, dt)
Example #14
0
# -----------------------
# End of model generation
# -----------------------

# ------------------------
# Start of static analysis
# ------------------------

# Load control with variable load steps
#                            init  Jd  min  max
ops.integrator("LoadControl", 1.0, 1, 1.0, 10.0)

# Convergence test
#                  tolerance maxIter displayCode
ops.test("EnergyIncr", 1.0E-10, 20, 0)

# Solution algorithm
ops.algorithm("Newton")

# DOF numberer
ops.numberer("RCM")

# Cosntraint handler
ops.constraints("Plain")

# System of equations solver
ops.system("SparseGeneral", "-piv")
#ops.system("ProfileSPD")

# Analysis for gravity load
Example #15
0
# ----------------------- 
# End of model generation
# -----------------------


# ------------------------
# Start of static analysis
# ------------------------

# Load control with variable load steps
#                            init  Jd  min   max
ops.integrator("LoadControl", 1.0, 1) 

# Convergence test
#                     tolerance maxIter displayCode
ops.test("NormUnbalance", 1.0E-10, 20, 0)

# Solution algorithm
ops.algorithm("Newton")

# DOF numberer
ops.numberer("RCM")

# Cosntraint handler
ops.constraints("Plain")

# System of equations solver
ops.system("ProfileSPD")

# Analysis for gravity load
ops.analysis("Static")
Example #16
0
# --------------------------------------------------------------------
# Start of static analysis (creation of the analysis & analysis itself)
# --------------------------------------------------------------------

# create the system of equation
ops.system("ProfileSPD")

# create the DOF numberer
ops.numberer("RCM")

# create the constraint handler
ops.constraints("Plain")

# create the convergence test
ops.test("EnergyIncr", 1.0E-12, 10)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the load control with variable load steps
ops.integrator("LoadControl", 1.0, 1, 1.0, 10.0)

# create the analysis object
ops.analysis("Static")

# Perform the analysis
ops.analyze(10)

# --------------------------
# End of static analysis
# ------------------------------
# Start of analysis generation
# ------------------------------
# create SOE
op.system('UmfPack')
# create DOF number
op.numberer('RCM')
# create constraint handler
op.constraints('Transformation')
# create integrator
op.integrator('LoadControl', timeStep, NumSteps)
# create algorithm
op.algorithm('Newton')
# create test
op.test('NormUnbalance', 1, 1000, 1)
# create analysis object
op.analysis('Static')
# perform the analysis
op.analyze(NumSteps)
op.loadConst('-time', 1.00)
op.wipeAnalysis()

#----------------------------------------------------------------------------------
###################################################################################
# Stage 2 : Perform Dynamic analysis with excess pore pressure generation in soil
###################################################################################

Total_Time = 30
#total time of simulation
dt = 0.01
Example #18
0
ops.model('basic', '-ndm', 1, '-ndf', 1)
ops.uniaxialMaterial('Elastic', 1, 3000.0)

ops.node(1, 0.0)
ops.node(2, 72.0)

ops.fix(1, 1)

ops.element('Truss', 1, 1, 2, 10.0, 1)
ops.timeSeries('Linear', 1)
ops.pattern('Plain', 1, 1)
ops.load(2, 100.0)

ops.constraints('Transformation')
ops.numberer('ParallelPlain')
ops.test('NormDispIncr', 1e-6, 6, 2)
ops.system('ProfileSPD')
ops.integrator('Newmark', 0.5, 0.25)
# ops.analysis('Transient')
ops.algorithm('Linear')
ops.analysis('VariableTransient')

ops.analyze(5, 0.0001, 0.00001, 0.001, 10)
time = ops.getTime()
print(f'time: ', ops.getTime())
approx_vtime = 0.0001 + 0.001  # One step at target, then one step at maximum
assert 0.99 < time / approx_vtime < 1.01, (time, approx_vtime)
ops.setTime(0.0)
# Can still run a non-variable analysis - since analyze function has multiple dispatch.
ops.analyze(5, 0.0001)
time = ops.getTime()
Example #19
0
# ------------------------------
# Start of analysis generation
# ------------------------------

# create the system of equation
ops.system("BandGeneral")

# create the DOF numberer, the reverse Cuthill-McKee algorithm
ops.numberer("RCM")

# create the constraint handler, a Plain handler is used as h**o constraints
ops.constraints("Plain")

# Create the convergence test, the norm of the residual with a tolerance of 
# 1e-12 and a max number of iterations of 10
ops.test("NormDispIncr", 1.0E-12, 10, 3)

# create the solution algorithm, a Newton-Raphson algorithm
ops.algorithm("Newton")

# create the integration scheme, the LoadControl scheme using steps of 0.1
ops.integrator("LoadControl", 0.1)

# create the analysis object 
ops.analysis("Static")

# ------------------------------
# End of analysis generation
# ------------------------------

def get_inelastic_response(mass,
                           k_spring,
                           f_yield,
                           motion,
                           dt,
                           xi=0.05,
                           r_post=0.0):
    """
    Run seismic analysis of a nonlinear SDOF

    :param mass: SDOF mass
    :param k_spring: spring stiffness
    :param f_yield: yield strength
    :param motion: list, acceleration values
    :param dt: float, time step of acceleration values
    :param xi: damping ratio
    :param r_post: post-yield stiffness
    :return:
    """

    op.wipe()
    op.model('basic', '-ndm', 2, '-ndf', 3)  # 2 dimensions, 3 dof per node

    # Establish nodes
    bot_node = 1
    top_node = 2
    op.node(bot_node, 0., 0.)
    op.node(top_node, 0., 0.)

    # Fix bottom node
    op.fix(top_node, opc.FREE, opc.FIXED, opc.FIXED)
    op.fix(bot_node, opc.FIXED, opc.FIXED, opc.FIXED)
    # Set out-of-plane DOFs to be slaved
    op.equalDOF(1, 2, *[2, 3])

    # nodal mass (weight / g):
    op.mass(top_node, mass, 0., 0.)

    # Define material
    bilinear_mat_tag = 1
    mat_type = "Steel01"
    mat_props = [f_yield, k_spring, r_post]
    op.uniaxialMaterial(mat_type, bilinear_mat_tag, *mat_props)

    # Assign zero length element
    beam_tag = 1
    op.element('zeroLength', beam_tag, bot_node, top_node, "-mat",
               bilinear_mat_tag, "-dir", 1, '-doRayleigh', 1)

    # Define the dynamic analysis
    load_tag_dynamic = 1
    pattern_tag_dynamic = 1

    values = list(-1 * motion)  # should be negative
    op.timeSeries('Path', load_tag_dynamic, '-dt', dt, '-values', *values)
    op.pattern('UniformExcitation', pattern_tag_dynamic, opc.X, '-accel',
               load_tag_dynamic)

    # set damping based on first eigen mode
    angular_freq = op.eigen('-fullGenLapack', 1)**0.5
    alpha_m = 0.0
    beta_k = 2 * xi / angular_freq
    beta_k_comm = 0.0
    beta_k_init = 0.0

    op.rayleigh(alpha_m, beta_k, beta_k_init, beta_k_comm)

    # Run the dynamic analysis

    op.wipeAnalysis()

    op.algorithm('Newton')
    op.system('SparseGeneral')
    op.numberer('RCM')
    op.constraints('Transformation')
    op.integrator('Newmark', 0.5, 0.25)
    op.analysis('Transient')

    tol = 1.0e-10
    iterations = 10
    op.test('EnergyIncr', tol, iterations, 0, 2)
    analysis_time = (len(values) - 1) * dt
    analysis_dt = 0.001
    outputs = {
        "time": [],
        "rel_disp": [],
        "rel_accel": [],
        "rel_vel": [],
        "force": []
    }

    while op.getTime() < analysis_time:
        curr_time = op.getTime()
        op.analyze(1, analysis_dt)
        outputs["time"].append(curr_time)
        outputs["rel_disp"].append(op.nodeDisp(top_node, 1))
        outputs["rel_vel"].append(op.nodeVel(top_node, 1))
        outputs["rel_accel"].append(op.nodeAccel(top_node, 1))
        op.reactions()
        outputs["force"].append(
            -op.nodeReaction(bot_node, 1))  # Negative since diff node
    op.wipe()
    for item in outputs:
        outputs[item] = np.array(outputs[item])

    return outputs