p_beam
Purpose
Element property function for beams
Syntax
il = p_beam('default')
il = p_beam('database','name')
il = p_beam('dbval ProId','name');
il = p_beam('dbval -unit TM ProId name');
Description
This help starts by describing the main commands : p_beam Database and Dbval. Supported p_beam subtypes and their formats are then described.
[Database,Dbval] ...
p_beam contains a number of defaults obtained with p_beam('database') or
p_beam('dbval MatId'). You can select a particular entry of the database with using a name matching the database entries. You can also automatically compute the properties of standard beams
| circle r |
beam with full circular section of radius r |
| rectangle b h |
beam with full rectangular section of width b and height h. |
For example, you will obtain the section property row with EltId 100 associated with a circular cross section of 0.05 m or a rectangular 0.05 × 0.01 m cross section using
pro = p_beam('database 100 rectangle .05 .01')
il = p_beam(pro.il,'dbval 101 circle .05')
il(end+1,1:6)=[102 fe_mat('p_beam','SI',1) 0 0 0 1e-5];
il = fe_mat('convert SITM',il);
il = p_beam(il,'dbval -unit TM 103 rectangle .05 .01')
Beam format description and subtypes
Element properties are described by the row of an element property matrix or a data structure with an .il field containing this row (see section 7.4). Element property functions such as p_beam support graphical editing of properties and a database of standard properties.
For a tutorial on material/element property handling see section 5.3.1. For a programmers reference on formats used to describe element properties see section 7.4.
1 : standard
p_beam currently only supports a single format (fe_mat property subtype)
[ProID type J I1 I2 A k1 k2 Lump]
| ProID |
element property identification number |
| type |
identifier obtained with fe_mat('p_beam','SI',1) |
| J |
torsional stiffness parameter (often different from polar moment of inertia I1+I2) |
| I1 |
moment of inertia for bending plane 1 defined by a third node nr or the vector vx vy vz. For a case with a beam along x and plane 1 the xy plane I1 is equal to Iz = òS y2 ds. |
| I2 |
moment of inertia for bending plane 2 (containing the beam and orthogonal to plane 1. |
| A |
section area |
| k1 |
(optional) shear factor for motion in plane 1 (when not 0, a
Timoshenko beam element is used). The effective
area of shear is given by k1A. |
| k2 |
(optional) shear factor for direction 2 |
| lump |
(optional) request for lumped mass model |
bar1 elements only use the section area. All other parameters are ignored.
beam1 elements use all parameters. Without correction factors (k1 k2 not given or set to
0), the beam1 element is the standard Bernoulli-Euler 12 DOF element
based on linear interpolations for traction and torsion and cubic
interpolations for flexion (see Ref. [34] for example). When non zero shear factors are given, the bending properties are
based on a Timoshenko beam element with selective reduced integration of the
shear stiffness [42].
No correction for rotational inertia of sections is used.
See also
Section 5.3.1, section 7.4, fe_mat©1991-2007 by SDTools
