# Reaction force on bolt (SPRINGA element)

**URL:** <https://prepomax.discourse.group/t/reaction-force-on-bolt-springa-element/3581>\
**Category:** General Questions\
**Tags:** results\
**Created:** [July 24, 2026, 10:29am UTC](https://prepomax.discourse.group/t/reaction-force-on-bolt-springa-element/3581 "2026-07-24T10:29:07Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [July 27, 2026, 7:28am UTC](https://prepomax.discourse.group/t/reaction-force-on-bolt-springa-element/3581/5 "2026-07-27T07:28:29Z")

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> [@Marco](#):
>
> If I want to change the Spring with a beam, how can I change the code?

In CalculiX, beams are not really the best choice for bolt modeling, but you can find an example here: [Beam Element connections between Two plates (2D)](https://prepomax.discourse.group/t/beam-element-connections-between-two-plates-2d/2821) and here: [Why the top plate displacement is zero?](https://prepomax.discourse.group/t/why-the-top-plate-displacement-is-zero/2667) and in many other threads on this forum such as: [Simplified bolt connection with beam element and rigid constraints](https://prepomax.discourse.group/t/simplified-bolt-connection-with-beam-element-and-rigid-constraints/3328)

In short words, you need at the very least (to avoid having to define second-order elements for circular profile):

```auto
*ELEMENT, TYPE=B31
element_number, node_1, node_2
...
*BEAM SECTION, MATERIAL=..., ELSET=..., SECTION=RECT
width, height
x, y, z

```

or with second-order elements:

```auto
*ELEMENT, TYPE=B32
element_number, node_1, node_2
...
*BEAM SECTION, MATERIAL=..., ELSET=..., SECTION=CIRC
diameter

```

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