# Beams and truss don't connect in Z

**URL:** <https://calculix.discourse.group/t/beams-and-truss-dont-connect-in-z/973>\
**Category:** Analysis issues\
**Created:** [January 27, 2022, 8:39pm UTC](https://calculix.discourse.group/t/beams-and-truss-dont-connect-in-z/973 "2022-01-27T20:39:36Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![vicmw](https://avatars.discourse-cdn.com/v4/letter/v/6de8d8/32.png) [@vicmw](https://calculix.discourse.group/u/vicmw)\
**Post date:** [January 27, 2022, 8:39pm UTC](https://calculix.discourse.group/t/beams-and-truss-dont-connect-in-z/973/1 "2022-01-27T20:39:36Z")

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There seems to be a bug where the connection between a T3D2 or T3D3 element and B31, B32, or B32R elements is not enforced in the Z direction. Happens in 2.17 and 2.19. Here’s an example. The horizontal and vertical members should be be connected but they come apart.

 ![deformed view](https://global.discourse-cdn.com/free1/uploads/calculix/original/1X/7d5af2816b37037321f9ab61a6ff2abc7fa99ad7.png)

```auto
*NODE
1,0,0,0
2,0,0.625,0
3,0,0.875,0
4,0,0.5,0
5,0,0.125,0
6,0,0.75,0
7,0,0.375,0
8,0,1,0
9,0,1.125,0
10,0,0.25,0
11,-0.5,0.5,0
*ELEMENT,TYPE=B31,ELSET=1
1,5,1
2,10,5
3,9,8
4,8,3
5,3,6
6,6,2
8,7,10
9,2,4
10,4,7
*ELEMENT,TYPE=T3D2,ELSET=2
7,11,4
*MATERIAL,NAME=Material
*ELASTIC,TYPE=ISOTROPIC
200000000000,0
*BEAM SECTION,ELSET=1,MATERIAL=Material,SECTION=RECT
0.05,0.05
1,0,0
*SOLID SECTION,ELSET=2,MATERIAL=Material
0.0025
*BOUNDARY
1,1,3,0
9,1,3,0
11,1,3,0
*STEP
*STATIC
*CLOAD
2,3,1000
*NODE FILE
U
*END STEP

```

---

<div class="post-metadata">

**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [January 27, 2022, 9:53pm UTC](https://calculix.discourse.group/t/beams-and-truss-dont-connect-in-z/973/2 "2022-01-27T21:53:19Z")

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Such connections between elements of different types can be hard to realize. In Abaqus, you could use tie constraint but in CalculiX it may not be possible. Of course, it’s much easier with beam elements only:

 ![beam to beam](https://global.discourse-cdn.com/free1/uploads/calculix/original/1X/510a006bf6a11adab1f3a5451a0ccd21466c666a.png)

In practice, that’s how it would be done in most cases.

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<div class="post-metadata">

**Author:** ![vicmw](https://avatars.discourse-cdn.com/v4/letter/v/6de8d8/32.png) [@vicmw](https://calculix.discourse.group/u/vicmw)\
**Post date:** [January 28, 2022, 12:03am UTC](https://calculix.discourse.group/t/beams-and-truss-dont-connect-in-z/973/3 "2022-01-28T00:03:28Z")

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In general, you can’t use a beam because the other end might also be connected to beams, not like this simple example.

But you gave me an idea. You can connect them with 3 \*EQUATIONS instead of a shared node and it works.

```auto
*EQUATION
2
4,1,1,12,1,-1
*EQUATION
2
4,2,1,12,2,-1
*EQUATION
2
4,3,1,12,3,-1

```

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<div class="post-metadata">

**Author:** ![xyont](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/xyont/32/3553_2.png) [@xyont](https://calculix.discourse.group/u/xyont)\
**Post date:** [August 17, 2022, 12:44pm UTC](https://calculix.discourse.group/t/beams-and-truss-dont-connect-in-z/973/4 "2022-08-17T12:44:48Z")

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assign equation to released rotational of end nodes beam element may frequently raised to unstable structures due to lack of rotational restraint around it axes.

 ![2022-08-17 19_18_09-CalculiX GraphiX](https://global.discourse-cdn.com/free1/uploads/calculix/original/1X/226e7c8798f60c222744c114abbf7933ffdad670.png)