stiffpy

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This repo has code for structural analysis with the direct stiffness method, a matrix method that uses stiffness relations. The code can handle various elements, loads and boundary conditions.

This project is still in development

Install stiffpy

To install stiffpy you need to manually clone the repository.

Features

• Shear Force Diagrams
• Bending Moment Diagrams
• Displacements
• Fixed Supports
• Hinged Supports
• Custom Supports
• Point Actions in Nodes and Elements
• Distributed Forces in Elements
• Hinged Elements
• Releases at Element end nodes

Programs

• Truss
• Beam
• Frame
• Spring
• Linear Triangle (Soon)

Examples

Spring Example

# Import Modules
from stiffpy.spring import *
# Define Nodes
node_1 = Node(0)
node_2 = Node(10)
node_3 = Node(20)
# Define Members
member_1 = Member(node_1, node_2, 10)
member_2 = Member(node_2, node_3, 20)
# Define Beam
spring = Spring()
# Add Node Loads
node_2.force = Force(-10)
# Add Restrains
node_1.restrains = True
node_3.restrains = True
# Add Members to Beam Object
spring.members = member_1
spring.members = member_2
spring.solve()
print(spring.reactions)

Beam Example

"""
Integrated Matrix Analysis of Structures, Mario Paz & William Leigh
Illustrative Example 1.4, pp 17
"""
# Import Modules
from stiffpy.material import Material
from stiffpy.section import Section
from stiffpy.beam import *
# Define Material and Section
material = Material(E=29e3, f_y=1, f_u=1)
section = Section(A=1, Ix=882, material=material)
# Define Nodes
node_1 = Node(0)
node_2 = Node(90)
node_3 = Node(180)
node_4 = Node(300)
node_5 = Node(396)
# Define Members
member_1 = Member(node_1, node_2, section)
member_2 = Member(node_2, node_3, section)
member_3 = Member(node_3, node_4, section)
member_4 = Member(node_4, node_5, section)
# Define Beam
beam = Beam()
# Add Node Loads
node_2.force = Force(-10)
node_3.moment = Moment(-50)
# Add Member Loads
member_1.forces = [10, Force(-30)]
member_1.forces = [20, Force(-10)]
member_2.distributed_loads = [0, DistributedForce(-.1, -.1, 90)]
member_3.distributed_loads = [20, DistributedForce(-.1, -.2, 75)]
member_4.distributed_loads = [0, DistributedForce(-.05, -.05, 96)]
member_4.moments = [48, Moment(100)]
# Add Restrains
node_1.restrains = [True, True]
node_3.restrains = [True, False]
node_4.restrains = [True, False]
node_5.restrains = [True, True]
# Add Members to Beam Object
beam.members = member_1
beam.members = member_2
beam.members = member_3
beam.members = member_4
beam.solve()
print(beam.reactions)

Truss Example

"""
Integrated Matrix Analysis of Structures, Mario Paz & William Leigh
Illustrative Example 6.1, pp 207
"""
# Import modules
from stiffpy.material import Material
from stiffpy.section import Section
from stiffpy.truss import *
# Define Material and Section
material = Material(E=30e3, f_y=1, f_u=1)
section = Section(A=10, Ix=882, material=material)
# Define Nodes
node_1 = Node((0, 0))
node_2 = Node((100, 0))
node_3 = Node((0, 100))
# Define Members
member_1 = Member(node_1, node_2, section)
member_2 = Member(node_1, node_3, section)
member_3 = Member(node_3, node_2, section)
# Define Beam
truss = Truss()
# Add Node Loads
node_3.force = Force((10, 0))
# Add Restrains
node_1.restrains = [True, True]
node_2.restrains = [False, True]
# Add Members to Beam Object
truss.members = member_1
truss.members = member_2
truss.members = member_3
truss.solve()
print(truss.reactions)

Frame Example

# Import Modules
from stiffpy.material import Material
from stiffpy.section import Section
from stiffpy.frame import *
# Define Material
material = Material(E=2e7, f_y=1, f_u=1)
# Define Section
section = Section(A=11.8*0.0254**2, Ix=518*0.0254**4, material=material)
# Define Frame Object
frame = Frame()
# Define Nodes
node_1: Node = Node([0, 0])
node_2: Node = Node([0, 10])
node_3: Node = Node([5, 10])
node_4: Node = Node([10, 10])
node_5: Node = Node([15, 5])
node_6: Node = Node([5, 5])
# Define Members
member_1 = Member(node_1, node_2, section)
member_2 = Member(node_2, node_3, section)
member_3 = Member(node_3, node_4, section)
member_4 = Member(node_4, node_5, section)
member_5 = Member(node_3, node_6, section)
# Add Actions
member_1.distributed_loads = [0, DistributedForce([0, -10], [0, -10], 10)]
member_2.distributed_loads = [0, DistributedForce([0, -10], [0, -10], 5)]
member_3.distributed_loads = [0, DistributedForce([0, -10], [0, -10], 5)]
member_4.distributed_loads = [0, DistributedForce([10/2**0.5, -10/2**0.5],
    [10/2**0.5, -10/2**0.5], 5*2**0.5)]
# Add Restrains
node_1.restrains = [True, True, True]
node_5.restrains = [True, True, True]
node_6.restrains = [True, True, True]
# Add Members to Frame Objects
frame.members = member_1
frame.members = member_2
frame.members = member_3
frame.members = member_4
frame.members = member_5
# Solve
frame.solve()
print(frame.reactions)
frame.draw_deformations(20)

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Todo's

• Deformed shape error
• Instead of using a vector for the rotation of the local coordinates, use euler angles.
• Improve typing

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About

Developer: Eduardo Paolo Oros
Email: [email protected]