> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/cable-stayed-bridge-workflow/tower-csb/pylon-csb.md).

# Pylon \[CSB]

The pylons for the bridge can be modeled using this object in the workflow.

## Pylon

**Bridge:** This parameter can be used to specify the bridge for which the pylons are being modeled.

**Station:** This parameter can be used to define the location of the pylon in the longitudinal direction.

**Bottom Transverse Offset:** The transverse offset with respect to PGL, where a negative value will indicate the left side when looking along PGL, can be specified using this parameter.

{% hint style="info" %}
The positive direction of the Y-axis will be to the left when looking upstream along the PGL. However, based on the requests of engineers who have been using OpenBrIM for their bridge projects, positive transverse offset values will indicate the right-hand side when looking upstream along the PGL. This distinction should be taken into account when defining the location of bridge elements using transverse offset values (where positive transverse offset indicates the right side), as well as when making definitions related to FEM and loading (where positive Fy indicates the left side along the PGL).
{% endhint %}

**Section Data:**

* **Vertical Length (Starts from Bottom):** The length of the pylon, starting from the bottom elevation, can be specified using this parameter.
* **Start Section:** The start/bottom section for each segment of a pylon can be assigned using this parameter.
* **End Section:** The end/top section of a pylon can be assigned using this parameter.
* **End Transverse Offset (from Bottom):** For the top/end section of a pylon segment, this parameter can be used to define the transverse offset value with respect to the **Bottom Transverse Offset** parameter (not with respect to PGL). For instance, if a straight pylon is needed, this value should be defined as "0."

**Bottom Elevation:** The bottom elevation of the pylon can be defined using this parameter, where the alignment is defined as 0, and the downward direction is indicated with negative values.

{% hint style="warning" %}
For each pylon, there must be one row of definition under the Pylon Tab, not for each varying pylon segment, for the FEM to be generated in a precise manner. The section and transverse offset variations can be defined using the parameters under Section Data. ![image-20241223-121603.png](https://openbrim.atlassian.net/wiki/download/attachments/2848718926/image-20241223-121603.png?api=v2)
{% endhint %}

## FEA

The finite element model of each pylon segment can be defined in terms of FEM using the parameters under the FEA tab.

**Generate FEM? \[Yes/No]:** Setting the "Generate Fem" parameter to "No" can disable the analytical representation of the pylon.

**Mesh Size:** The mesh size parameter can be utilized to set the maximum distance for a single finite element line.

**Bottom Fixity \[Fixed/Stiffness Matrix]:** The **Bottom Fixity** of the pylon can be defined with one of the following options: **Fixed**: This assumes the base of the pylon is fully restrained, resisting all translations and rotations. **Stiffness Matrix**: The bottom fixity is adjusted based on a defined stiffness matrix, allowing for partial restraint, depending on the stiffness values assigned.

**6x6 Stiffness Matrix:** If the **Stiffness Matrix** option is chosen, the 6x6 stiffness matrix can be specified. This matrix defines the resistance in three translational and three rotational degrees of freedom:

**Tx, Ty, Tz**: Translational stiffness values along the X, Y, and Z axes.

**Rx, Ry, Rz**: Rotational stiffness values about the X, Y, and Z axes.

By adjusting these parameters, the model can simulate varying degrees of support flexibility at the base of the pylon segment, providing more realistic behavior depending on the structure's design and foundation conditions.

## Referencing Objects

**Cables:** Back-reference list populated automatically with the stay cables that anchor into this pylon. Informational; defined via the referencing cable objects.


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