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.
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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. |
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 figures below.
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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: In the overhang regions, users can choose whether or not to include taper by selecting "yes" or "no," as shown in the figure below. This input will impact the haunch load computation.
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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).
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
Longitudinal Mesh Size: Since girders are typically used for modeling elements and generating FEM models, such as for the deck, and cable-stayed bridges may not have girders, mesh generation in the longitudinal direction can be controlled with this parameter.
Transverse Mesh Size: Since girders are typically used for modeling elements and generating FEM models, such as for the deck, and cable-stayed bridges may not have girders, 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.
Longitudinal Boundary
The longitudinal boundary of the deck can be overridden by the properties defined using the parameters in this tab.
Start Support Line: Select a support line for the definition of the longitudinal boundary.
Offset from Start Support Line: Define the offset value needed for the start support line.
End Support Line: Select a support line for the end boundary definition.
Offset from End Support Line: Define the offset value needed for the end support line.
Transverse Boundary
The transverse boundary of the deck can be overridden by the properties defined using the parameters in this tab.
PGL to Left at Start: When looking upstream along the PGL, the left side distance from the PGL at the start can be specified with this parameter.
PGL to Left at End: When looking upstream along the PGL, the left side distance from the PGL at the end can be specified with this parameter.
PGL to Right at Start: When looking upstream along the PGL, the right side distance from the PGL at the start can be specified with this parameter.
PGL to Right at End: When looking upstream along the PGL, the right side distance from the PGL at the end can be specified with this parameter.
Continuous at Start[Yes/No] : 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[Yes/No]: 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.
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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.