if (displayMode == "displayON"):
# a window to plot the nodal displacements versus load for node 3
ops.recorder("plot", "Node41.out", "Node_3_Xdisp", 10, 340, 300, 300, "-columns", 3, 1, "-dT", 0.1)
# ------------------------------
# End of recorder generation
# ------------------------------
# ------------------------------
# Start of lateral load analysis
# ------------------------------
# Perform an eigenvalue analysis
lam = ops.eigen(2)
Tstart = 2.0*math.pi/math.sqrt(lam[0])
print("Fundamental period at start of pushover analysis: ", Tstart, "sec\n")
# Change the integrator to take a min and max load increment
ops.integrator("LoadControl", 1.0, 4, 0.02, 2.0)
# record once at time 0
ops.record()
# Perform the pushover analysis
# Set some parameters
maxU = 10.0; # Max displacement
controlDisp = 0.0
ok = ops.analyze(1)
while ((ok == 0) and (controlDisp < maxU)):
if (displayMode == "displayON"):
# a window to plot the nodal displacements versus load for node 3
ops.recorder("plot", "Node41.out", "Node_3_Xdisp", 10, 340, 300, 300,
"-columns", 3, 1, "-dT", 0.1)
# ------------------------------
# End of recorder generation
# ------------------------------
# ------------------------------
# Start of lateral load analysis
# ------------------------------
# Perform an eigenvalue analysis
lam = ops.eigen(2)
Tstart = 2.0 * math.pi / math.sqrt(lam[0])
print("Fundamental period at start of pushover analysis: ", Tstart, "sec\n")
# Change the integrator to take a min and max load increment
ops.integrator("LoadControl", 1.0, 4, 0.02, 2.0)
# record once at time 0
ops.record()
# Perform the pushover analysis
# Set some parameters
maxU = 10.0
# Max displacement
controlDisp = 0.0
ok = ops.analyze(1)
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
nep,
fmt_interp='b-',
az_el=(-68., 39.),
fig_wi_he=fig_wi_he,
endDispFlag=0)
plt.title('3d 3-element cantilever beam')
# - 2
opsv.plot_defo(sfac, 19, fmt_interp='b-', az_el=(6., 30.), fig_wi_he=fig_wi_he)
plt.title('3d 3-element cantilever beam')
# - 3
nfreq = 6
eigValues = ops.eigen(nfreq)
modeNo = 6
sfac = 2.0e1
opsv.plot_mode_shape(modeNo,
sfac,
19,
fmt_interp='b-',
az_el=(106., 46.),
fig_wi_he=fig_wi_he)
plt.title(f'Mode {modeNo}')
sfacN = 1.e-2
sfacVy = 5.e-2
sfacVz = 1.e-2