> 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/spliced-i-girder-bridge-workflow/superstructure-spig/diaphragm-spig/continuity-diaphragm-spig.md).

# Continuity Diaphragm \[SPIG]

## Continuity Diaphragm

**Connected Girders at Start (Downstation):** Girders on the downstation side of the diaphragm that are tied into it. The 3D geometry and FE mesh of the diaphragm are built from the picked girders' top/bottom elevations.

**Connected Girders at End (Upstation):** Girders on the upstation side of the diaphragm.

**Depth:** Vertical depth of the diaphragm's 3D representation.

**Additional Overhang Length Transverse Dir. (Left):** Additional distance from the leftmost girder centerline outward beyond that girder in the transverse direction.

**Additional Overhang Length Transverse Dir. (Right):** Additional distance from the rightmost girder centerline outward beyond that girder in the transverse direction.

**Thickness (Downstation w\.r.t. Support Line):** Thickness of the diaphragm measured from the support line toward the downstation side.

**Thickness (Upstation w\.r.t. Support Line):** Thickness of the diaphragm measured from the support line toward the upstation side.

**Material:** Material assigned to the diaphragm. Pick a material from *Properties > Materials*.

## Quantities

**Rebar Density(per cubic yard):** Estimated rebar weight per unit concrete volume for the continuity diaphragm, used by downstream quantity takeoff reports.

## FEM

**Rigid Section (Cap Connection):** Rigid section assigned to the FE element that links the diaphragm to the pier-cap top when Cap Connection is Yes. Choose a section that represents a rigid constraint (very high EA/EI).

**Cap Connection \[Yes/No]:** When Yes, a FE connection element is generated between the diaphragm top and the pier cap top nodes.

**Cap Connection Type \[Rigid/Pin]:** Controls whether the cap-to-diaphragm connection is rigid or pinned.

**Deck Connection \[Yes/No]:** When Yes, a FE connection element is generated between the diaphragm top and the deck. Use Yes when the diaphragm and deck are poured in the same stage; use No when the diaphragm is built before the deck so staged construction FEM is correct.


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