# Concrete Deck \[TB]

## General

The longitudinal deck length is defined by the support lines selected in this section, while the transverse direction deck properties are determined by the cross-section defined in the previous stage.

**Cross-Sections:**

* **Cross Section Location (Support Line):** Support lines for defining the cross-section locations should be selected using this parameter.

{% hint style="info" %}
To generate a deck, at least two row definitions must be made. The required definitions are the support line and its cross-section at the start station, as well as the support line and its cross-section at the end station. However, the **Offset from Support Line** parameter should not be used for either of these definitions, as it is not the correct parameter for extending the deck before the start station or after the end station. Instead, the **Initial Cantilever Length** and **End Cantilever Length** parameters on 3D Settings Tab should be used.
{% endhint %}

* **Offset From Support Line:** If the entered cross-section is intended to vary between the start and end stations, this parameter can be used to assign different cross-sections to the corresponding locations.
* **Cross Section:** Select the cross-section defined prior to this step.
* **Skew Angle:** A positive skew value rotates the start and end location in a clockwise direction, while a negative skew value rotates the cross-section counterclockwise. Selecting a skew value for any interior support line (pier) will impact the finite element generation logic at that location.
* **Variation w/Next Segment \[None/Linear/Parabola]:** For visual representation, refer to the documentation on the concrete deck in the Cable Stayed Bridge workflow.

**Girders:** To create the 3D geometry for the haunch and finite element mesh of the deck, input for the girder is required. To ensure accurate extraction of composite forces, the library component will generate a minimum of two shell elements between two girders.

**Taper \[No/Yes]:** In the overhang regions, users can choose whether or not to include taper by selecting **Yes** or **No**. This input will impact the haunch load computation.

**Overhang Bottom Flat \[No/Yes]:** When Taper is **No**, this parameter controls whether the bottom of the overhang region is rendered flat (**Yes**) or follows the haunch profile (**No**). Affects only the 3D representation.

**Material:** Users should assign a material to the concrete deck. This definition will directly impact both the Finite Element Analysis (FEA) and the Finite Element Model (FEM). The user must provide a value.

**Deck Reinforcement Data**

The reinforcement data for the deck will be automatically utilized in the code checking process for the superstructure elements.

* **Start Station:** Specify the start station for the reinforcements.
* **End Station:** Specify the end station for the reinforcements.
* **Deck Rebar Material:** This parameter can be used to set a material for the deck rebars defined in this row. A different material can be used for each row defined. Materials can either be imported or assigned from previously defined ones in the **Properties > Materials** section.
* **Longitudinal Deck Rebar Spacing (Top Layer):** Specify the spacing of longitudinal rebars in the top layer.
* **Longitudinal Deck Rebar Spacing (Bottom Layer):** Specify the spacing of longitudinal rebars in the bottom layer.
* **Longitudinal Deck Rebar (Top Layer):** Specify the rebars for the top layer. Rebars can either be imported or assigned from previously defined options under **Properties > Rebars**.
* **Longitudinal Deck Rebar (Bottom Layer):** Specify the rebars for the bottom layer. Rebars can either be imported or assigned from previously defined options under **Properties > Rebars**.
* **Clear Cover (Top):** Specify the clear cover for the top rebars.
* **Clear Cover (Bottom):** Specify the clear cover for the bottom rebars.
* **Concrete Creep Adjustment Factor:** To incorporate the effects of concrete creep in stress calculations that involve the application of long-term loads to the composite section in regions of negative flexure, the area of the longitudinal reinforcement can be conservatively adjusted by dividing it by the "Concrete creep adjustment factor." The concrete is assumed to transfer the force from the longitudinal deck steel to the rest of the cross-section, with concrete creep acting to reduce that force over time. It is important to note that assuming a value greater than 1 is a conservative approach and is not mandated by the AASHTO LRFD BDS. As such, it is not recommended to use this assumption in normal design practice. When using the default value of 1, the reinforcement area will remain unaltered.

## FEA

**Long. Mesh Size:** Since girders are typically used for modeling elements and generating FEM models for the deck, and truss bridges may not have continuous girders under the deck, mesh generation in the longitudinal direction can be controlled with this parameter.

**Trans. Mesh Size:** Since girders are typically used for modeling elements and generating FEM models for the deck, and truss bridges may not have continuous girders under the deck, mesh generation in the transverse direction can be controlled with this parameter.

**Expansion Joint End Releases:** The deck mesh will create two nodes at the same location for the entered station and connect them with springs. Spring stiffness will be assigned based on the values entered by the user in respective directions. This is another way to model discontinuous decks, expansion joints, or even hinges.

* **Station:** Station of the end release or expansion joint.
* **Tx-Ty-Tz-Rx-Ry-Rz:** Utilize a "free" or a small stiffness value in the direction where you wish to enable release. For instance, you can set Tx, Ty, Rx, Ry, and Rz as "free," while keeping Tz as "fixed." In case stability issues arise, using a small stiffness value in the direction causing instability can be a helpful solution.

**Deck Property Overrides:** If you wish to override the thickness or material properties of the deck FE surface elements in specific regions, utilize property overrides.

**Overrides**

* **Override Thickness \[Yes/No]:** If the thickness value for override should be defined, use the option **Yes** for this parameter.
* **Thickness:** This parameter can only be specified if the **Override Thickness** parameter is defined with the option **Yes**; otherwise, this parameter will not be applicable.
* **Override Material \[Yes/No]:** If the material needs to be overridden, select the option **Yes** for this parameter.
* **Material:** This parameter can only be specified if the **Override Material** parameter is defined with the option **Yes**; otherwise, this parameter will not be applicable.
* **Mesh at Override Boundary \[Yes/No]:** If you wish to apply additional constraints to the mesh at the boundary you've defined for the override, choose **Yes**. Typically, selecting **Yes** can complicate the meshing process, so opt for **No** if it doesn't significantly impact your results.

**Continuous at Start \[No/Yes]:** Users can choose whether the deck is continuous or discontinuous at the start region, which affects the generation of the finite element model. To ensure continuity between two different decks, users can select the "continuous" option for the end location of the first deck and the start location of the second deck. If the user wants to define the deck as discontinuous with a gap between two decks, they can select the "discontinuous" option and define girders end locations accordingly. Selecting continuous or discontinuous options will not affect the behavior if only one deck is defined.

**Continuous at End \[No/Yes]:** Users can choose whether the deck is continuous or discontinuous at the end region, which affects the generation of the finite element model. To ensure continuity between two different decks, users can select the "continuous" option for the end location of the first deck and the start location of the second deck. If the user wants to define the deck as discontinuous with a gap between two decks, they can select the "discontinuous" option and define girders end locations accordingly. Selecting continuous or discontinuous options will not affect the behavior if only one deck is defined.

**Additional Mesh Lines:** Select Girder Layout objects to add extra mesh-constraint lines in the deck FE mesh. The selected objects' paths become gridlines, forcing element edges to align with those paths — useful for concentrated loads, cable anchors, or complex geometry.

**Mesh Algorithm \[GridMesh/MeshAdapt/Automatic/Initial mesh only/Delaunay/Frontal-Delaunay/Frontal-Delaunay for Quads/Packing of Parallelograms/Quasi-structured Quad]:** Selects the algorithm used to generate the finite-element mesh of the deck. Default is **GridMesh**. For non-linear cross-section variation or custom deck-edge alignments, **Frontal-Delaunay for Quads** is generally preferred.

## 3D Settings

**Curve Refinement:** The curve refinement parameter is employed to discretize the deck along the longitudinal direction. This parameter is only applicable to the 3D view and does not affect the FEA model. If you do not observe a smooth curve, increasing this value can be helpful.

**Initial Cantilever Length of Deck:** This parameter defines the cantilever length of the deck at the start. It affects only the 3D model of the object and does not impact the FEM (Finite Element Model) of the deck.

**End Cantilever Length of Deck:** This parameter defines the cantilever length of the deck at the end. Like the initial cantilever length, it only influences the 3D model and does not affect the FEM of the deck.

**Drip Notch \[No/Yes]:** Enables a drip notch along the underside of the overhang. A drip notch (groove or protrusion) interrupts the flow of surface water and prevents seepage toward the underside of the deck that can otherwise corrode supporting members.

**Right Top Chamfer:** Chamfer dimension applied to the right-top edge of the deck section.

**Right Bot Chamfer:** Chamfer dimension applied to the right-bottom edge of the deck section.

**Left Top Chamfer:** Chamfer dimension applied to the left-top edge of the deck section.

**Left Bot Chamfer:** Chamfer dimension applied to the left-bottom edge of the deck section.

**Additional Deck Thickness:** Adjustment added to the deck thickness derived from the cross-section. Affects only the 3D model.

**Barrier Region Width:** Width of the region at each deck edge reserved for the barrier footprint in the 3D model.

## Quantities

The quantities obtained from parameter definitions are presented to the user as read-only values under this tab.

**Min Cross Section Area:** Minimum cross-section area across the deck length (Read-only).

**Max Cross Section Area:** Maximum cross-section area across the deck length (Read-only).

**Min Perimeter:** Minimum cross-section perimeter across the deck length (Read-only).

**Max Perimeter:** Maximum cross-section perimeter across the deck length (Read-only).

**Length Min Path:** Minimum path length along the modeled deck (Read-only).

**Length @COG:** Path length along the deck's center of gravity (Read-only).

**Length Max Path:** Maximum path length along the modeled deck (Read-only).

**Top Surface Area:** Total top surface area of the deck (Read-only).

**Min Width:** Minimum deck width across the length (Read-only).

**Max Width:** Maximum deck width across the length (Read-only).

**Left Overhang Width (Avg.):** Average left overhang width along the deck length (Read-only).

**Right Overhang Width (Avg.):** Average right overhang width along the deck length (Read-only).

**Rebar Calculation Method \[By Density/By Length]:** Controls how deck reinforcement weight is computed. **By Density** multiplies the deck volume by a user-specified rebar density; **By Length** sums the rebar lengths from the Deck Reinforcement Data rows. The selected method determines which quantity outputs below are displayed.

**Rebar Density(per cubic yard):** Rebar mass per unit concrete volume. Used only when **Rebar Calculation Method** is **By Density**.

**Rebar Weight (By Density):** Deck volume multiplied by **Rebar Density** (Read-only; shown when **By Density** is selected).

**Longitudinal Reinforcement Length (Bot Layer):** Total length of longitudinal rebars in the bottom layer, derived from deck width and rebar spacing (Read-only; shown when **By Length** is selected).

**Longitudinal Reinforcement Length (Top Layer):** Total length of longitudinal rebars in the top layer (Read-only; shown when **By Length** is selected).

**Longitudinal Reinforcement Weight (Bot Layer):** Weight of the bottom-layer longitudinal rebars (Read-only; shown when **By Length** is selected).

**Longitudinal Reinforcement Weight (Top Layer):** Weight of the top-layer longitudinal rebars (Read-only; shown when **By Length** is selected).

**Total Rebar Weight (By Length):** Combined weight of top- and bottom-layer longitudinal rebars (Read-only; shown when **By Length** is selected).

**Volume:** Total concrete volume of the deck (Read-only).

**Weight:** Total weight of the deck, derived from volume and material density (Read-only).

**Material (Read-Only):** Name of the material assigned in the General section (Read-only).

## IFC

**Predefined Type \[Approach\_Slab/Baseslab/Floor/Landing/Paving/Roof/Sidewalk/Trackslab/Wearing/Userdefined/Notdefined]:** IFC predefined type for the deck. Used when exporting to IFC.

**Parent \[Bridge/Superstructure/Deck/Substructure/Foundation/Approach\_Structure/Retaining\_Structure]:** IFC parent container for the deck in the exported model hierarchy.

## Referencing Objects

**Construction States:** Construction States referencing this deck (Read-only).

**Barriers:** Barrier objects placed on this deck (Read-only).

**Rails:** Rail objects placed on this deck (Read-only).

**Bicycle Railings:** Bicycle-railing objects placed on this deck (Read-only).

**Cables:** Cable objects anchored to this deck (Read-only).


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