> 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/steel-i-girder-bridge-workflow/substructure-sig/pier-sig/steel-i-girder-bent-cap-sig/diaphragm-sig.md).

# Diaphragm \[SIG]

The Diaphragm object serves as a connection element between I-Girders . Both the FEM and 3D models are generated based on the parameter definitions listed below.

## Diaphragm

**Girders:** Specify the girders for which the diaphragms will be generated.

**Station on Girders (from Right End):** Assume the right-hand side as the starting point for station definition when viewed up-station from the alignment.

**Thickness:** This parameter is used to specify the thickness of the diaphragm in the bridge’s transverse direction.

**Material:** Assign a material to the diaphragm. Materials can be selected from previously defined options or imported as needed.

**Top Offset (from Bottom of Top Flange):** For a visual representation, refer to the figure below.

**Bottom Offset (from Top of Bottom Flange):** For a visual representation, refer to the figure below.

![image-20240913-125522.png](https://openbrim.atlassian.net/wiki/download/attachments/2575138834/image-20240913-125522.png?api=v2)

## IFC

**Type:** The IFC entity type for BIM export. Available options include:

* IfcBeam (default)
* IfcBridgePart
* IfcElementAssembly
* IfcMember
* IfcBuildingElementProxy

**Predefined Type:** The IFC Predefined Type is specified using this parameter. Available options include:

* DIAPHRAGM (default)
* BEAM
* GIRDER
* CROSS\_BRACING
* USERDEFINED
* NOTDEFINED

**Parent \[Bridge/Superstructure/Deck/Substructure/Foundation/Approach\_Structure/Retaining\_Structure]:** The IFC Parent is specified using this parameter to define the hierarchy relationship in the IFC model.

## Quantities

**Rebar Density(per cubic yard):** The density of reinforcing steel per cubic yard of concrete. Used to calculate the rebar weight based on the diaphragm volume.

**Rebar Weight:** The calculated rebar weight based on the rebar density and diaphragm volume. (Read-only)

**Volume:** The total volume of the diaphragm concrete. (Read-only)

**Weight:** The total weight of the diaphragm based on volume and material density. (Read-only)


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