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1D Elements

MIDAS PYTHON

Creation Methods

There are three methods available to create 1D elements:

  • Single Element (Main Class) : eg. Truss , Beam
    Creates one element connecting two nodes by their IDs:i and j.
    Use this when we know the specific node IDs to connect.

  • Start and End location (SEmethod) : eg. Truss.SE , Beam.SE
    Creates multiple equally spaced elements between a given start and end location. http://localhost:8000/Element/1D/

  • Start, Direction and Length (SDL method) : eg. Truss.SDL , Beam.SDL
    It creates equally divided elements at Start location along the the direction with given total length.

SS

TRUSS

A nested class within Element used to create truss elements.

Object Attributes

ID: Element ID
TYPE: Element type = 'TRUSS'
MATL: Material ID of the truss element
SECT: Section ID of the truss element
NODE: Nodes of element in list. eg: [1,2]
ANGLE: Beta angle of the truss element

To create truss element we have total 3 methods :

1. Truss

Element.Truss(i:int, j:int, mat = 1, sect = 1, angle = 0, group = '' , id = 0)
Creates a truss between nodes i and j.

Parameters

  • i: Node ID of i-th end
  • j: Node ID of j-th end
  • mat (default=1: Material ID of the truss element
  • sect (default=1): Section ID of the truss element
  • angle (default=0): Beta angle of the truss element
  • group (default=''): Structure group of the element (can be str or list eg. 'SG' or ['SG1','SG2'])
  • id (default=0): Manually assign an ID. If 0, ID will be auto-assigned.

Examples

Node(0,0,0)    # Create Node at 0,0,0 with ID = 1(default)
Node(1,1,1)    # Create Node at 1,1,1 with ID = 2(default)

beam1 = Element.Truss(1,2)  # Create Truss connecting Node 1 and Node 2 (default ID = 1)

Node.create()
Element.create()

2. Truss.SE

Element.Truss.SE(s_loc: list, e_loc: list, n: int = 1, mat, sect, angle, group, id)
Creates n truss elements between start and end location.

Parameters

  • s_loc: Start location. [x,y,z]
  • e_loc: End location. [x,y,z]
  • n (default=1): Number of elements
  • mat,sect,angle,group,id : Same as Element.Truss() method

Examples

Element.Truss.SE([0,0,0],[10,0,0],10) # Create 10 truss between (0,0,0) and (10,0,0) 

Node.create()
Element.create()

3. Truss.SDL

Element.Truss.SDL(s_loc: list, dir: list, l: float, n: int = 1, mat, sect, angle, group, id)
Creates n truss elements along a straight line defined by direction dir and length l starting at s_loc.

Parameters

  • s_loc: Starting location [x, y, z]
  • dir: Direction vector [dx, dy, dz]
  • l: Total length of element
  • n (default=1): Number of elements
  • mat,sect,angle,group,id : Same as Element.Truss() method

Examples

Element.Truss.SDL([0,0,0],[0,0,1],10) # Create a vertical truss of length 10 at (0,0,0)

Node.create()
Element.create()

BEAM

A nested class within Element used to create Beam elements.

Object Attributes

ID: Element ID
TYPE: Element type = 'BEAM'
MATL: Material ID of the beam element
SECT: Section ID of the beam element
NODE: Nodes of element in list. eg: [1,2]
ANGLE: Beta angle of the beam element

To create Beam element we have total 3 methods :

1. Beam

Element.Beam(i:int, j:int, mat = 1, sect = 1, angle = 0, group = '' , id = 0)
Creates a Beam between nodes i and j.

Parameters

  • i: Node ID of i-th end
  • j: Node ID of j-th end
  • mat (default=1: Material ID of the Beam element
  • sect (default=1): Section ID of the Beam element
  • angle (default=0): Beta angle of the Beam element
  • group (default=''): Structure group of the element (can be str or list eg. 'SG' or ['SG1','SG2'])
  • id (default=0): Manually assign an ID. If 0, ID will be auto-assigned.

Examples

Node(0,0,0)    # Create Node at 0,0,0 with ID = 1(default)
Node(1,1,1)    # Create Node at 1,1,1 with ID = 2(default)

beam1 = Element.Beam(1,2)  # Create Beam connecting Node 1 and Node 2 (default ID = 1)

Node.create()
Element.create()

2. Beam.SE

Element.Beam.SE(s_loc: list, e_loc: list, n: int = 1, mat, sect, angle, group, id)
Creates n Beam elements between start and end location.

Parameters

  • s_loc: Start location. [x,y,z]
  • e_loc: End location. [x,y,z]
  • n (default=1): Number of elements
  • mat,sect,angle,group,id : Same as Element.Beam() method

Examples

Element.Beam.SE([0,0,0],[10,0,0],10) # Create 10 Beam between (0,0,0) and (10,0,0) 

Node.create()
Element.create()

3. Beam.SDL

Element.Beam.SDL(s_loc: list, dir: list, l: float, n: int = 1, mat, sect, angle, group, id)
Creates n Beam elements along a straight line defined by direction dir and length l starting at s_loc.

Parameters

  • s_loc: Starting location [x, y, z]
  • dir: Direction vector [dx, dy, dz]
  • l: Total length of element
  • n (default=1): Number of elements
  • mat,sect,angle,group,id : Same as Element.Beam() method

Examples

Element.Beam.SDL([0,0,0],[0,0,1],10) # Create a vertical beam of length 10 at (0,0,0)

Node.create()
Element.create()

TENSION

A nested class within Element used to create tension-only elements, hooks, and cables.

Object Attributes

ID: Element ID
TYPE: Element type = 'COMPTR'
MATL: Material ID of the compression element
SECT: Section ID of the compression element
NODE: Nodes of element in list. eg: [1,2]
ANGLE: Beta angle of the compression element
STYPE: Subtype of compression element (1=Compression-only, 2=Gap)
TENS: Allowable tension or initial compression force
T_LIMIT: Compression limit value
T_bLMT: Compression limit flag (automatically set when T_LIMIT is provided)
NON_LEN: Non-linear length parameter (for Gap subtype)

Tension Element

Element.Tension(i:int, j:int, stype:int, mat = 1, sect = 1, angle = 0, group = '' , id = 0, non_len = None, cable_type = None, tens = None, t_limit = None)
Creates a tension element between nodes i and j.

Parameters

  • i: Node ID of i-th end
  • j: Node ID of j-th end
  • stype: Tension element subtype (1=Tension-only, 2=Hook, 3=Cable)
  • mat (default=1): Material ID of the tension element
  • sect (default=1): Section ID of the tension element
  • angle (default=0): Beta angle of the tension element
  • group (default=''): Structure group of the element (can be str or list eg. 'SG' or ['SG1','SG2'])
  • id (default=0): Manually assign an ID. If 0, ID will be auto-assigned.
  • non_len (default=None): Non-linear length parameter for Hook/Cable
  • cable_type (default=None): Cable type for stype=3 (1=Pretension, 2=Horizontal, 3=Lu)
  • tens (default=None): Initial tension force or allowable compression
  • t_limit (default=None): Tension limit value

Examples

Node(0,0,0)    # Create Node at 0,0,0 with ID = 1(default)
Node(1,1,1)    # Create Node at 1,1,1 with ID = 2(default)

# Simple tension-only member
tension1 = Element.Tension(1,2,stype=1)

# Tension-only with allowable compression and tension limit
tension2 = Element.Tension(1,2,stype=1,tens=0.5,t_limit=-15)

# Hook element with slack length
hook1 = Element.Tension(3,4,stype=2,non_len=0.5)

# Cable with initial tension and catenary effects
cable1 = Element.Tension(5,6,stype=3,cable_type=3,tens=1000.0,non_len=0.1)

Node.create()
Element.create()

Subtypes

1. Tension-only (stype=1)

  • Transfers tension forces only
  • Can have allowable compression (tens parameter)
  • Can have tension limit (t_limit parameter)

2. Hook (stype=2)

  • Has slack length defined by non_len parameter
  • Only active when stretched beyond slack length

3. Cable (stype=3)

  • Supports catenary analysis
  • Requires cable_type parameter
  • Can have initial tension and slack length

COMPRESSION

A nested class within Element used to create compression-only elements and gaps.

Object Attributes

ID: Element ID
TYPE: Element type = 'COMPTR'
MATL: Material ID of the compression element
SECT: Section ID of the compression element
NODE: Nodes of element in list. eg: [1,2]
ANGLE: Beta angle of the compression element
STYPE: Subtype of compression element (1=Compression-only, 2=Gap)
TENS: Allowable tension or initial compression force
T_LIMIT: Compression limit value
T_bLMT: Compression limit flag (automatically set when T_LIMIT is provided)
NON_LEN: Non-linear length parameter (for Gap subtype)

Compression Element

Element.Compression(i:int, j:int, stype:int, mat = 1, sect = 1, angle = 0, group = '' , id = 0, tens = None, t_limit = None, non_len = None)
Creates a compression element between nodes i and j.

Parameters

  • i: Node ID of i-th end
  • j: Node ID of j-th end
  • stype: Compression element subtype (1=Compression-only, 2=Gap)
  • mat (default=1): Material ID of the compression element
  • sect (default=1): Section ID of the compression element
  • angle (default=0): Beta angle of the compression element
  • group (default=''): Structure group of the element (can be str or list eg. 'SG' or ['SG1','SG2'])
  • id (default=0): Manually assign an ID. If 0, ID will be auto-assigned.
  • tens (default=None): Allowable tension or initial compression force
  • t_limit (default=None): Compression limit value
  • non_len (default=None): Non-linear length parameter for gap

Examples

Node(0,0,0)    # Create Node at 0,0,0 with ID = 1(default)
Node(1,1,1)    # Create Node at 1,1,1 with ID = 2(default)

# Simple compression-only member
comp1 = Element.Compression(1,2,stype=1)

# Compression-only with tension limit and buckling limit
comp2 = Element.Compression(1,2,stype=1,tens=27,t_limit=-15)

# Gap element with initial gap
gap1 = Element.Compression(3,4,stype=2,non_len=0.25)

Node.create()
Element.create()

Subtypes

1. Compression-only (stype=1)

  • Transfers compression forces only
  • Can have allowable tension (tens parameter)
  • Can have compression limit (t_limit parameter)

2. Gap (stype=2)

  • Has initial gap defined by non_len parameter
  • Only active when compressed beyond gap length

Examples

1. Portal Frame

h = 3.5        # Height of each storey
w = 4.0       # Width of each Bay

n_storey = 10 # Total no. of storey
n_bay = 5      # Total no. of bay

for i in range(n_bay+1):
    for j in range(n_storey):
        if i!=n_bay:
            Element.Beam.SDL([i*w,0,j*h],[0,0,1],h,sect=1)  # Column -> Sect ID = 1
            Element.Beam.SDL([i*w,0,(j+1)*h],[1,0,0],w,sect=5) # Beam -> Sect ID = 5
        else:
            Element.Beam.SDL([i*w,0,j*h],[0,0,1],h,sect=1) # Column -> Sect ID = 1

Node.create()
Element.create()
NODE GRID

2. Warren Truss

span = 20.5  # Span of truss
n_div = 8    # No. of bottom divisions
h = 2.5      # Height of truss

dx = 0.5*span/n_div

Element.Truss.SDL([0,0,0],[1,0,0],span,n_div)

Element.Truss.SDL([dx,0,h],[1,0,0],span-2*dx,n_div-1)

for i in range(n_div):
    Element.Truss(i+1,i+2+n_div)
    Element.Truss(i+2,i+2+n_div)

Node.create()
Element.create()
NODE GRID