structure pile create command

Syntax

structure pile create keyword

Primary keywords:

by-line    by-nodeids    by-ray    by-zone-face

Create a pile consisting of a collection of beam finite elements. The three main keywords articulate three creation techniques: create a collection of elements that lie between a begin point and an end point (by-line); create a single element from two existing nodes (by-nodeids); and create a collection of elements that lie along a ray (by-ray).

The elements of the pile will be assigned the group name Pile N where N is the ID number of the pile. And the beginning and ending nodes will be assigned the group name Pile Begin and Pile End. See the group, group-begin, and group-end keywords to customize these assignments.

by-line v1 v2 [pilecreateblock]

create a collection of elements that lie along a straight line between the locations v1 and v2. New nodes associated with the elements will also be created (see the id keyword). The nodal connectivity of each new element will be ordered such that the direction from v1 to v2 corresponds with the direction from the begin point to the end point. If there are objects (zones in FLAC3D and 3DEC, and particles in PFC3D) in these locations, the element will be attached to the objects at its nodes such that the translational degrees-of-freedom are rigidly connected to the objects and the rotational degrees-of-freedom are free. If no attachment to objects is desired, then the links may be deleted with the command structure link delete after creating and positioning the element.

by-nodeids i1 i2 [pilecreateblock]

specify the ID numbers (i1, i2) of two nodes that will define the element. These nodes must already exist—nodes can be created with the structure node create command. Ordering of the nodes defines the beam element coordinate system as follows. The positive \(x\)-direction lies along the line from i1 to i2, and the \(y\)-direction is found by projecting the global \(y\)- or \(x\)-directions onto the element cross-section. The \(y\)-direction can also be modified with the property direction-y.

The new element will not be attached to any objects (zones in FLAC3D and 3DEC, and particles in PFC3D); if you wish to attach it to objects, then after creating it, position its nodes with the structure node initialize position command (which will create links and set appropriate attachment conditions for all nodes that are moved into an object.

by-ray v1 v2 f [pilecreateblock]

creates a collection of elements that lie along a straight line starting at v1, proceeding in the direction specified by v2 for a distance given by f. New nodes associated with the element will also be created (see the id keyword). The nodal connectivity of each new element will be ordered such that the direction from v1 corresponds with the direction from the begin point to the end point. If there are objects (zones in FLAC3D and 3DEC, and particles in PFC3D) in these locations, the element will be attached to the objects at its nodes such that the translational degrees-of-freedom are rigidly connected to the objects and the rotational degrees-of-freedom are free. If no attachment to objects is desired, then the links may be deleted with the command structure link delete after creating and positioning the element.

by-zone-face (2D ONLY) [pilecreateblock] <range>

create new elements that are attached to the set of 2-noded edges (faces) in the range. By default, only surface faces will be considered, and the internal keyword can be used to select internal faces. New nodes associated with each element will also be created. The nodes of each element will be ordered counter-clockwise with respect to the outside of the zone faces, thereby making each element \(y\) axis point outward from the zone face. The orientation of the \(y\) axis can be reversed with the reverse keyword. Note that after creating the elements with this command, the zones may be deleted and the elements may be positioned by moving their nodes with the structure node initialize position command.

structure pile create Keyword Block

The following keywords may be optionally provided on element creation performed using any of the major keywords: by-line, by-nodeids, by-ray and by-zone-face.

distinct

Eliminate sharing of nodes among created elements. Every element will create a new set of nodes, even if they are at the same location in space and elements share the same ID number. This option is most commonly used with a later structure node join command to create links connecting nodes at the same location in order to apply custom inter-element behavior.

element-type keyword

Specify the type of finite element to be used by each structural element. If no element type is specified, then the element type will be Euler-Bernoulli. Note that the type of finite element is associated with each structural element when it is created and cannot subsequently be altered. The finite element type of existing structural elements is listed by the structure pile list element-type command. Plastic material behavior is supported only by the Euler-Bernoulli finite element. The value of the keyword supplied must be one of the following two beam finite elements (see Beam-Type Mechanical Behavior for a discussion of the beam-theory assumptions embodied in the two element types):

s

Attempt to match the string s to one of the available keywords below, and treats as that option.

euler-bernoulli

Euler-Bernoulli beam finite element (appropriate for modeling long thin beams)

timoshenko

Timoshenko beam finite element (appropriate for modeling short thick beams)

group s <slot s >

Assign all newly created elements to the group s. The optional keyword slot can be used to specify the group slot; if not specified, the group is assigned to the slot Default. Use of the group logic is described in Groups. If not specified, the default group name assigned will be Pile N where N is the ID number assigned to the pile.

group-begin s <slot s >

A group name that will be assigned to the first node of the elements created along a line or ray. The default name assigned will be Pile Begin.

group-end str:`s` <slot s >

A group name that will be assigned to the first node of the elements created along a line or ray. The default name assigned will be Pile End.

id i

Specify the ID that will be assigned to all new elements created by this command. If this value is not given, then the next available ID will be used. The ID controls potential joining of the two element end-nodes to an existing element as follows. At each end-node location, a new node is created unless all of the following conditions are fulfilled: 1) the ID is given; 2) an existing node is found near the potential new node location; and 3) the found node is part of a pile with ID equal to i.

maximum-length f

Break the element into segments no greater than length f. The segments setting, if provided, is overridden as needed by this setting.

reverse (2D ONLY)

Specifies that the orientation of the element will be reversed from the default, so that only the element \(y\) axis points in the other direction.

Note

reversing the \(y\)-direction will change the sign of the shear forces and moments in the beam elements. The magnitude will remain the same.

segments i

Break the element into i equal segments, creating new nodes as needed. The default value is 1, indicating that only one element will be created.

snap <b >

Indicate that the first and last positions of the element(s) created will attempt to “snap” to the location of the nearest structural node (attached to any element type) within a radius of 1/2 the element length. If only one end is snapped in this manner, then the entire line or ray created will be offset by the difference between the original and snapped positions. Note that a new node is created and snapped to the location of the nearest existing node - the element being created does not use an existing node as one of its end nodes. Use struct node join if you want to join the newly created node to the existing node.