# Arch Bracing \[TB] A linear bracing member that connects points on one or two arch ribs. Use to model diagonal, K-, or X-bracing between paired arches, or to add stiffeners within a single arch. Arch bracings contribute to lateral stability of the arch system and are designed under AASHTO LRFD 6.14.4.3 (lateral bracing of arches). ## General **Arch(es):** One or two arches that the bracing connects. Pick one arch for an intra-arch stiffener, or two arches for a lateral brace spanning between paired arch ribs. Required. **Location Type \[Relative (0-1)/Station]:** Chooses how **First Location** and **Second Location** are interpreted. **Relative** treats the values as normalized positions along the arch curve, where 0 is the first bearing and 1 is the second. **Station** treats the values as absolute X-coordinates (stations) along the alignment. **First Location (Relative/Station):** Location of the bracing's first end on the first arch. If Location Type is Relative, a value of 0 places it at the first bearing and 1 at the second bearing; values between 0 and 1 interpolate along the arch. If Location Type is Station, the value is the X station where the bracing attaches. **Second Location (Relative/Station):** Location of the bracing's second end on the second arch (or the same arch in single-arch mode). Same interpretation as First Location. **Section:** The Section library object used as the bracing cross-section. Picks from **Sections**. Required. Drives the 3D geometry, AASHTO 6.9 compression checks, and slenderness evaluation. **Orientation Angle:** Rotation of the section about the bracing's local tangent (beta angle). Use to roll the section into its strong-axis orientation. ## Offsets **Vertical Offset (point-1):** Vertical shift (Z) applied at the first connection point, in addition to the interpolated location on the arch. Positive is upward. **Horizontal Offset (point-1):** Transverse shift (Y) at the first connection point. Positive moves to the right when looking up-station (internal -Y application). **Longitudinal Offset (point-1):** Longitudinal shift (X) at the first connection point. Positive moves up-station. **Vertical Offset (point-2):** Vertical shift (Z) applied at the second connection point. **Horizontal Offset (point-2):** Transverse shift (Y) at the second connection point. **Longitudinal Offset (point-2):** Longitudinal shift (X) at the second connection point. ## 3D Detailing **Start Face Skew Angle (X-Axis):** Rotation of the start-face cutting plane about the local X-axis, useful for mitred cuts at the arch connection. **End Face Skew Angle (X-Axis):** Rotation of the end-face cutting plane about the local X-axis. **Start Face Skew Angle (Y-Axis):** Rotation of the start-face cutting plane about the local Y-axis. **End Face Skew Angle (Y-Axis):** Rotation of the end-face cutting plane about the local Y-axis. **Brace Opacity:** Display opacity of the bracing in the 3D view, 0 (transparent) to 1 (opaque). ## FEA Settings **Number of FE Segments:** Number of finite-element subdivisions generated along the bracing. Use 1 for a simple two-node strut; use more when buckling or P-delta effects need intermediate nodes along the member. **Merge Intermediate Nodes to Nearest \[No/Yes]:** When **Number of FE Segments** is greater than 1, controls whether the intermediate nodes are merged with any coincident bridge mesh nodes they land on. Endpoint nodes always merge. Only visible when Number of FE Segments > 1. ## Quantities **Min Section Area:** Minimum cross-section area along the bracing. (Read-only, may be slow on recompute.) **Max Section Area:** Maximum cross-section area along the bracing. (Read-only, may be slow on recompute.) **Total Surface Area:** Total exterior surface area including end faces. Used for painting/coating take-offs. (Read-only, may be slow on recompute.) **Min Cross Section Perimeter:** Smallest section perimeter along the bracing. (Read-only, may be slow on recompute.) **Max Cross Section Perimeter:** Largest section perimeter along the bracing. (Read-only, may be slow on recompute.) **Volume:** Total volume of the bracing member. (Read-only, may be slow on recompute.) **Min Length Path:** Shortest path length (inner fiber). (Read-only, may be slow on recompute.) **Length @COG Path:** Length measured along the section's center of gravity. (Read-only, may be slow on recompute.) **Max Length Path:** Longest path length (outer fiber). (Read-only, may be slow on recompute.) **Weight:** Computed weight, Volume × section-material density. (Read-only, may be slow on recompute.) **Material:** Material name assigned through the section. (Read-only) **Section:** Section name assigned to the bracing. (Read-only) ## IFC **Type \[IfcBridge/IfcBridgePart/IfcBeam/IfcColumn/IfcSlab/IfcFooting/IfcPile/IfcBearing/IfcReinforcingBar/IfcReinforcingMesh/IfcTendon/IfcMechanicalFastener/IfcAlignment/IfcPositioningElement/IfcKerb/IfcGuardrail/IfcSurfaceFeature/IfcElementAssembly/IfcCableSegment/IfcSensor/IfcDistributionElement/IfcPlate/IfcWall/IfcRail/IfcRoad/IfcDiscreteAccessory/IfcDistributionSystem/IfcMember/IfcBuildingElementProxy]:** IFC entity class used on export. Default **IfcElementAssembly**, which groups the bracing as an assembled member in the IFC model. **Predefined Type \[Abutment/Accessory\_Assembly/Arch/Beam\_Grid/Braced\_Frame/Cross\_Bracing/Deck/DilatationPanel/EntranceWorks/Girder/Grid/Mast/Pier/Pylon/Rail\_Mechanical\_Equipment\_Assembly/Reinforcement\_Unit/Rigid\_Frame/Shelter/SignalAssembly/Slab\_Field/SumpBuster/SupportingAssembly/SuspensionAssembly/TrackPanel/Traction\_Switching\_Assembly/Traffic\_Calming\_Device/Truss/TurnoutPanel/UserDefined/NotDefined]:** Predefined-type attribute of the IFC entity. Default **CROSS\_BRACING** identifies the element as cross-bracing in the IFC model. **Parent \[Bridge/Superstructure/Deck/Substructure/Foundation/Approach\_Structure/Retaining\_Structure]:** Structural-hierarchy parent under which the bracing is nested. Default **SUPERSTRUCTURE**. **Properties:** Custom IFC property entries attached to this bracing on export. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.openbrim.org/templates/truss-bridge-workflow/arch-elements-tb/arch-bracing-tb.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.