G2 Example 1

G2Example1.py

from G2AnalysisSDOFNonlinearDynamic import *
from G2MaterialBilinear import *
import numpy as np
import matplotlib.pyplot as plt

# SI units: N, m, kg, sec.

# Spectrum range (natural periods)
minPeriod = 0.05
maxPeriod = 5.0
numPoints = 100
structuralPeriods = np.linspace(minPeriod, maxPeriod, numPoints)

# Stiffness
E = 1e4
alpha = 0.0

# Damping ratio
dampingRatio = 0.05

# Yield displacement
uy = 0.03e6
fy = E * uy

# Load ground motion
groundMotion = "GroundMotionElCentro.txt"
dt = 0.02
gmScaling = 1
gm = []
f = open(groundMotion, "r")
lines = f.readlines()
for oneline in lines:
    splitline = oneline.split()
    for j in range(len(splitline)):
        value = 9.81 * float(splitline[j]) * gmScaling
        gm.append(value)
gm = np.array(gm)
duration = dt * (len(gm)-1)

# Loop over natural periods
uMax = []
vMax = []
aMax = []
vMaxPseudo = []
aMaxPseudo = []
for i in range(numPoints):

    # Mass from natural period
    M = (structuralPeriods[i]/2/np.pi)**2 * E

    # Run analysis
    material = bilinearMaterial(['Bilinear', E, fy, alpha])
    t, uTrack, vTrack, aTrack, dudx, dvdx, dadx, dnl = nonlinearDynamicSDOFAnalysis(duration, dt, material, M, dampingRatio, gm, gmScaling, [])

    # Pick up maximum responses
    Sd = np.max(np.abs(uTrack))
    uMax.append(Sd)
    vMax.append(np.max(np.abs(vTrack)))
    vMaxPseudo.append(2*np.pi/structuralPeriods[i] * Sd)
    aMax.append(np.max(np.abs(aTrack)))
    aMaxPseudo.append((2*np.pi/structuralPeriods[i])**2 * Sd)

# Plot displacement response spectrum
plt.ion()
plt.figure()
plt.autoscale(True)
plt.grid(True)
plt.xlabel("$T_n$ [sec.]")
plt.ylabel("$S_d$ [m]")
plt.title("Displacement Response Spectrum")
plt.plot(structuralPeriods, uMax, 'k-', linewidth=1.0)
plt.savefig('Figure1.pdf', format='pdf')
print('\n'"Click somewhere in the plot to continue...")
plt.waitforbuttonpress()

# Plot velocity response spectrum + pseudo-velocity spectrum
plt.ion()
plt.figure()
plt.autoscale(True)
plt.grid(True)
plt.xlabel("$T_n$ [sec.]")
plt.ylabel("$S_v$ [m/s]")
plt.title("Velocity Response Spectrum")
plt.plot(structuralPeriods, vMax, 'b-', linewidth=1.0, label="Maximum velocity")
plt.plot(structuralPeriods, vMaxPseudo, 'r-', linewidth=1.0, label="Pseudo: $\omega_n S_d$")
plt.legend(loc='lower right')
plt.savefig('Figure2.pdf', format='pdf')
print('\n'"Click somewhere in the plot to continue...")
plt.waitforbuttonpress()

# Plot (total) acceleration response spectrum + pseudo-acceleration spectrum
plt.ion()
plt.figure()
plt.autoscale(True)
plt.grid(True)
plt.xlabel("$T_n$ [sec.]")
plt.ylabel("$S_a$ [$m/s^2$]")
plt.title("Acceleration Response Spectrum")
plt.plot(structuralPeriods, aMax, 'b-', linewidth=1.0, label="Maximum acceleration")
plt.plot(structuralPeriods, aMaxPseudo, 'r-', linewidth=1.0, label="Pseudo: $\omega_n^2 S_d$")
plt.legend(loc='upper right')
plt.savefig('Figure3.pdf', format='pdf')
print('\n'"Click somewhere in the plot to continue...")
plt.waitforbuttonpress()