/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
Isect Ismstr                
dm df            
NIP Iref Y0 Z0        
If NIP > 0, add NIP cards defining the subsection parameters (each integration point per line)
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Yi Zi Area        

If Isect > 0, add following 2 lines

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
NITR   L1 L2        
Blank Line
Add flag for rotational DOF for the beam nodes.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
ω DOF                  

Definition

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)

 
Isect Section type. 6
=0 (Default)
Integrated beam.
=1
Predefined rectangular section.
=2
Predefined circular section.
= 3
Predefined rectangular section with Gauss-Lobatto quadrature.
= 4
Predefined circular section with Gauss-Lobatto quadrature.
= 5
Predefined circular section. 6

(Integer)

 
Ismstr Small strain option flag.
=0 (Default)
Set to 4.
=1
Small strain formulation from t = 0.
=4
Full geometric nonlinearities.

(Integer)

 
dm Beam membrane damping.

Default = 0.00 (Real)

 
df Beam flexural damping.

Default = 0.0001 (Real)

 
NIP Number of integration points (subsections).

Only for Isect =0; otherwise, NIP=0.

(Integer)

 
Iref Subsection center reference flag.

Only for Isect =0.

=0 (Default)
Subsection center is calculated as a barycenter of the integration points.
=1
Subsection center is defined by using local coordinates (Y0 and Z0).

(Integer)

 
Y0 Local Y coordinate of the section center.

Only for Isect =0.

(Real)

[ m ]
Z0 Local Z coordinate of the section center.

Only for Isect =0.

(Real)

[ m ]
Yi Local Y coordinate of the integration point.

(Real)

[ m ]
Zi Local Z coordinate of the integration point.

Only for Isect =0.

(Real)

[ m ]
Area Area of the subsection.

Only for Isect =0.

(Integer)

[ m 2 ]
NITR Option for integration points in predefined section for Isect > 0. 6.

(Integer)

 
L1 First size of the predefined section for Isect > 0. 6

(Real)

 
L2 Second size of the predefined section for Isect > 0. 6

(Real)

 
ω D O F 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
      ω X 1 ω Y 1 ω Z 1   ω X 2 ω Y 2 ω Z 2

Definition

Field Contents SI Unit Example
ω X 1 = 1 Rotation DOF about X at node 1 is released.

(Boolean)

 
ω Y 1 = 1 Rotation DOF about Y at node 1 is released.

(Boolean)

 
ω Z 1 = 1 Rotation DOF about Z at node 1 is released.

(Boolean)

 
ω X 2 = 1 Rotation DOF about X at node 2 is released.

(Boolean)

 
ω Y 2 = 1 Rotation DOF about Y at node 2 is released.

(Boolean)

 
ω Z 2 = 1 Rotation DOF about Z at node 2 is released.

(Boolean)

 

Example 1 (Integrated Beam)

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/2
unit for prop
                  Mg                  mm                   s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  2. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/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
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
/END
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Example 2 (Integrated Beam)

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/2
unit for prop
                  Mg                  mm                   s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  2. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/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
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
/END
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

  1. Small strain formulation is activated from time t=0, if Ismstr =1. It may be used for a faster preliminary analysis because Δ t is constant, but the accuracy of results is not ensured.
  2. If Ismstr =1, the strains and stresses which are given in material laws are engineering strains and stresses. Time history output returns true strains and stresses.

    clip0093
    Figure 1.
  3. The cross-section of the element is defined using up to 100 integration points (Figure 2). The element properties of the cross-section, i.e. area moments of inertia and area, are computed by Radioss as:(1)
    A = A i = ( d y i d z i )
    (2)
    I Z = A i ( y i 2 + 1 12 d y i 2 )
    (3)
    I Y = A i ( z i 2 + 1 12 d z i 2 )
  4. It can be used for deep beam cases (short beams). The use of several integration points in the section allows to get an elasto-plastic 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.

    cross-section_def
    Figure 2. Cross-section Definitions in the Integrated Beam
  5. For rectangular section: L1 is the rectangular size in Y-direction of the local beam coordinates system and L2 is the rectangular size in Z-direction. For circular section: L1 is the radius.
  6. Predefined cross-sections are available (circular or rectangular). Number of integration points in the section is prescribed via NITR depending on Isect and the chosen quadrature:
    • For Isect = 1 and 2. Integration points are distributed uniformly across the section according to the section type and NITR.
    • For Isect = 3. The section is rectangular, the distribution of the integration points corresponds to the Gauss-Lobatto quadrature with points on the edge. IP = NITR*NITR. The maximum NITR possible is 9 corresponding to 81 integration points.
    • For Isect = 4. The section is circular. The distribution of the integration points radially corresponds to Gauss-Lobatto 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 Isect = 5. The section is circular. Three options: NITR = 1, NITR = 9 and NITR = 17. Here the number of integration points is equal to NITR.


    • Figure 3.