1)Install python

2)Install OpenSeesPy package

pip install openseespy

import openseespy.opensees as ops

import numpy as np

import matplotlib.pyplot as plt

# Function to define the 3D structure

def define_structure():

ops.model('basic', '-ndm', 3, '-ndf', 6)

# Define nodes

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

ops.node(2, 0.0, 0.0, 3.0)

ops.node(3, 4.0, 0.0, 0.0)

ops.node(4, 4.0, 0.0, 3.0)

# Define fixities

ops.fix(1, 1, 1, 1, 1, 1, 1)

ops.fix(3, 1, 1, 1, 1, 1, 1)

# Define materials

ops.uniaxialMaterial('Elastic', 1, 3000.0)

# Define elements

ops.element('truss', 1, 1, 2, 10.0, 1)

ops.element('truss', 2, 3, 4, 10.0, 1)

ops.element('truss', 3, 2, 4, 10.0, 1)

ops.element('truss', 4, 1, 3, 10.0, 1)

def perform_ida(ground_motion_file, dt, scale_factors):

# Time series and pattern for ground motion

ops.timeSeries('Path', 1, '-filePath', ground_motion_file, '-dt', dt, '-factor', 1.0)

ops.pattern('UniformExcitation', 1, 1, '-accel', 1)

# Define recorder

ops.recorder('Node', '-file', 'disp.out', '-time', '-node', 4, '-dof', 1, 'disp')

# Run IDA for different scale factors

displacements = []

for scale in scale_factors:

ops.timeSeries('Path', 1, '-filePath', ground_motion_file, '-dt', dt, '-factor', scale)

ops.wipeAnalysis()

ops.system('BandGeneral')

ops.numberer('Plain')

ops.constraints('Transformation')

ops.integrator('Newmark', 0.5, 0.25)

ops.algorithm('Newton')

ops.analysis('Transient')

ops.analyze(int(ground_motion_duration/dt), dt)

disp = ops.nodeDisp(4, 1)

displacements.append(disp)

ops.remove('loadPattern', 1)

return displacements

# Main code

define_structure()

ground_motion_file = 'path/to/ground_motion.txt'

dt = 0.01

ground_motion_duration = 20.0 # duration of ground motion in seconds

scale_factors = np.linspace(0.1, 2.0, 20) # scale factors from 0.1 to 2.0

displacements = perform_ida(ground_motion_file, dt, scale_factors)

# Plot the IDA curve

plt.plot(scale_factors, displacements)

plt.xlabel('Scale Factor')

plt.ylabel('Peak Displacement (m)')

plt.title('IDA Curve')

plt.grid(True)

plt.show()

Mobin Saleh