Rotational dof's release. "-->Internal<---" steel connection

41

Hi,

No rotational degrees of freedom are allowed in nodes of MPC’s in which no knot was created (Manual). For that reason, Equation doesn’t work in-between rotational DOFs of beams.

This can be sorted by inducing knots on the desired nodes. Once done, one can stablish whatever combination of DOF’s for beam connections.

As an example I’m inducing a knot on beams at an intermediate node with an extra thickness.

Other options are available:

  1. the direction of the local normals in the elements participating in the node differ beyond a given amount. Notice that this also applies to neighboring elements having the inverse normal. Care should be taken that the elements in plates and similar structures are oriented in a consistent way to avoid the generation of knots and the induced nonlinearity.

  2. several types of elements participate (e.g. shells and beams).

  3. the thickness is not the same in all participating elements.

  4. the offset is not the same in all participating elements.

  5. a rotation or a moment is applied in the node (only for dynamic calculations)

I’m using the 3th one.

imagen
imagen411×604 22.1 KB

*NODE
1,0.05,0,1
2,0.05,1.05,1
3,0.05,0.1111111111111,1
4,0.05,0.2222222222222,1
5,0.05,0.3333333333333,1
6,0.05,0.4444444444444,1
7,0.05,0.5555555555556,1
8,0.05,0.6666666666667,1
9,0.05,0.7777777777778,1
10,0.05,0.8888888888889,1
11,0.05,1,1
12,0,1,1.05
13,0,1,0.1111111111111
14,0,1,0.2222222222222
15,0,1,0.3333333333333
16,0,1,0.4444444444444
17,0,1,0.5555555555556
18,0,1,0.6666666666667
19,0,1,0.7777777777778
20,0,1,0.8888888888889
21,0,1,1
22,0,1,0
*ELEMENT,TYPE=B31
1,11,2
2,1,3
3,3,4
4,4,5
5,5,6
6,6,7
7,7,8
8,8,9
9,9,10
10,10,11
11,21,12
12,22,13
13,13,14
14,14,15
15,15,16
16,16,17
17,17,18
18,18,19
19,19,20
20,20,21
*ELSET,ELSET=1
2
3
4
5
6
7
8
9
10
*ELSET,ELSET=2
12
13
14
15
16
17
18
19
20
*ELSET,ELSET=3
1
*ELSET,ELSET=4
11
*MATERIAL,NAME=STEEL
*ELASTIC,TYPE=ISOTROPIC
210000000000,0.3
*DENSITY
7850000
*MATERIAL,NAME=DUMMY_EXTRA_THICKNESS
*ELASTIC,TYPE=ISOTROPIC
1000000000,0
*BEAM SECTION,ELSET=1,MATERIAL=STEEL,SECTION=RECT
0.03,0.03
-1,0,0
*BEAM SECTION,ELSET=2,MATERIAL=STEEL,SECTION=RECT
0.03,0.03
0,1,0
*BEAM SECTION,ELSET=3,MATERIAL=DUMMY_EXTRA_THICKNESS,SECTION=RECT
0.03001,0.03
-1,0,0
*BEAM SECTION,ELSET=4,MATERIAL=DUMMY_EXTRA_THICKNESS,SECTION=RECT
0.03001,0.03
0,1,0
*BOUNDARY
1,3,,0
1,2,,0
1,1,,0
1,6,,0
1,5,,0
22,3,,0
22,2,,0
22,1,,0
22,6,,0
22,5,,0
*EQUATION
2
11,4,1,21,4,-1
*EQUATION
2
11,1,1,21,1,-1
*EQUATION
2
11,2,1,21,2,-1
*EQUATION
2
11,3,1,21,3,-1
*STEP
*STATIC
*CLOAD
1,3,-5.555555555556
3,3,-11.11111111111
4,3,-11.11111111111
5,3,-11.11111111111
6,3,-11.11111111111
7,3,-11.11111111111
8,3,-11.11111111111
9,3,-11.11111111111
10,3,-11.11111111111
11,3,-5.555555555556
*NODE FILE,GLOBAL=YES,OUTPUT=2D
U,RF
*EL FILE,OUTPUT=2D,SECTION FORCES
S,NOE,E,ENER
*END STEP

imagen
imagen708×647 4.21 KB

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