/PROP/TYPE18 (INT_BEAM)
Block Format Keyword Describes the integrated beam property set. This beam model is based on Timoshenko theory and takes into account transverse shear strain without warping in torsion.
It can be used for deep beam cases (short beams). Beam section and position of integration points can be either used as predefined or prescribed directly.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/PROP/TYPE18/prop_ID/unit_ID or /PROP/INT_BEAM/prop_ID/unit_ID  
prop_title  
I_{sect}  I_{smstr}  
d_{m}  d_{f}  
NIP  I_{ref}  Y_{0}  Z_{0} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

Y_{i}  Z_{i}  Area 
If I_{sect} > 0, add following 2 lines
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

NITR  L1  L2  
Blank Line 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

${\omega}_{\mathit{DOF}}$ 
Definitions
Field  Contents  SI Unit Example 

prop_ID  Property
identifier (Integer, maximum 10 digits) 

unit_ID  Unit Identifier (Integer, maximum 10 digits) 

prop_title  Property
title (Character, maximum 100 characters) 

I_{sect}  Section type. 6
(Integer) 

I_{smstr}  Small strain option flag.
(Integer) 

d_{m}  Beam membrane
damping. Default = 0.00 (Real) 

d_{f}  Beam flexural
damping. Default = 0.0001 (Real) 

NIP  Number of integration
points (subsections). Only for I_{sect} =0; otherwise, NIP=0. (Integer) 

I_{ref}  Subsection center
reference flag. Only for I_{sect} =0.
(Integer) 

Y_{0}  Local Y coordinate of the
section center. Only for I_{sect} =0. (Real) 
$\left[\text{m}\right]$ 
Z_{0}  Local Z coordinate of the
section center. Only for I_{sect} =0. (Real) 
$\left[\text{m}\right]$ 
Y_{i}  Local Y coordinate of the
integration point. (Real) 
$\left[\text{m}\right]$ 
Z_{i}  Local Z coordinate of the
integration point. Only for I_{sect} =0. (Real) 
$\left[\text{m}\right]$ 
Area  Area of the subsection.
Only for I_{sect} =0. (Integer) 
$\left[{\text{m}}^{2}\right]$ 
NITR  Option for integration
points in predefined section for
I_{sect} >
0. 6. (Integer) 

L1  First size of the
predefined section for
I_{sect} >
0. 6 (Real) 

L2  Second size of the
predefined section for
I_{sect} >
0. 6 (Real) 

${\omega}_{DOF}$  Rotation DOF code of nodes
1 and 2 (see detail input below). (6 Booleans) 
Detail of Rotation DOF Input Fields for Nodes 1 and 2
(1)1  (1)2  (1)3  (1)4  (1)5  (1)6  (1)7  (1)8  (1)9  (1)10 

${\omega}_{X1}$  ${\omega}_{Y1}$  ${\omega}_{Z1}$  ${\omega}_{X2}$  ${\omega}_{Y2}$  ${\omega}_{Z2}$ 
Definitions
Field  Contents  SI Unit Example 

${\omega}_{X1}$  = 1 Rotation DOF about X
at node 1 is released. (Boolean) 

${\omega}_{Y1}$  = 1 Rotation DOF about Y
at node 1 is released. (Boolean) 

${\omega}_{Z1}$  = 1 Rotation DOF about Z
at node 1 is released. (Boolean) 

${\omega}_{X2}$  = 1 Rotation DOF about X
at node 2 is released. (Boolean) 

${\omega}_{Y2}$  = 1 Rotation DOF about Y
at node 2 is released. (Boolean) 

${\omega}_{Z2}$  = 1 Rotation DOF about Z
at node 2 is released. (Boolean) 
Example
#RADIOSS STARTER
#12345678910
/UNIT/2
unit for prop
Mg mm s
#12345678910
# 2. MATERIALS:
#12345678910
/PROP/TYPE18/4/2
Integrated beam  bXh=10X10 with 4 integration points (subsections)
# Isect Ismstmr
0 0
# dm df
0 0
# NIP Iref Y0 Z0
4 1 0 0
# Y Z Area
2.5 2.5 25
2.5 2.5 25
2.5 2.5 25
2.5 2.5 25
# OmegaDOF
000 000
#12345678910
#ENDDATA
/END
#12345678910
Example
#RADIOSS STARTER
#12345678910
/UNIT/2
unit for prop
Mg mm s
#12345678910
# 2. MATERIALS:
#12345678910
/PROP/TYPE18/4/2
Integrated beam  4 integration points in predefined section bXh=10X10
# Isect Ismstmr
1 0
# dm df
0 0
# NIP Iref Y0 Z0
0 1 0 0
# NITR L1 L2
2 10 10
# OmegaDOF
000 000
#12345678910
#ENDDATA
/END
#12345678910
Comments
 Small strain formulation is activated from time t=0, if I_{smstr} =1. It may be used for a faster preliminary analysis because $\text{\Delta}t$ is constant, but the accuracy of results is not ensured.
 If I_{smstr} =1, the strains and stresses which are given in material laws are engineering strains and stresses. Time history output returns true strains and stresses.
 The crosssection of the element is
defined using up to 100 integration points (Figure 2). The element properties of the crosssection,
i.e. area moments of inertia and area, are computed by Radioss as:
(1) $$A={\displaystyle \sum {A}_{i}={\displaystyle \sum \left(d{y}_{i}d{z}_{i}\right)}}$$(2) $${I}_{Z}={\displaystyle \sum {A}_{i}\left({y}_{i}{}^{2}+\frac{1}{12}d{y}_{i}{}^{2}\right)}$$(3) $${I}_{Y}={\displaystyle \sum {A}_{i}\left({z}_{i}{}^{2}+\frac{1}{12}d{z}_{i}{}^{2}\right)}$$  It can be used for deep beam cases (short beams). The use of several integration points in the section allows to get an elastoplastic model in which von Mises criteria is written on each integration point and the section can be partially plastified contrary to the classical beam element (TYPE3). Compatible with material LAW1, LAW2, and LAW36. However, as the element has only one integration point in its length, it is not recommended to use a single beam element per line of frame structure in order to take into account the plasticity progress in length, as well as in depth.
 For rectangular section: L1 is the rectangular size in Ydirection of the local beam coordinates system and L2 is the rectangular size in Zdirection. For circular section: L1 is the radius.
 Predefined crosssections are
available (circular or rectangular). Number of integration points in the section
is prescribed via NITR depending on
I_{sect} and the chosen
quadrature:
 For I_{sect} = 1 and 2. Integration points are distributed uniformly across the section according to the section type and NITR.
 For I_{sect} = 3. The section is rectangular, the distribution of the integration points corresponds to the GaussLobatto quadrature with points on the edge. IP = NITR*NITR. The maximum NITR possible is 9 corresponding to 81 integration points.
 For I_{sect} = 4. The section is circular. The distribution of the integration points radially corresponds to GaussLobatto quadrature with points on edge. Three options: NITR = 1, NITR = 17 and NITR = 25. Here the number of integration points is equal to NITR.
 For I_{sect} = 5. The section is circular. Three options: NITR = 1, NITR = 9 and NITR = 17. Here the number of integration points is equal to NITR.
