# Deck Construction \[TB] Composite deck pouring is a method of constructing a bridge deck where the deck and the supporting superstructure (trusses, floor beams, support beams) act together as a single structural unit, which significantly increases the load-carrying capacity of the bridge. In a truss bridge, the concrete deck is poured onto the floor/support-beam system and connected to the truss members through the deck-to-truss rigid-link configuration defined on this page. The composite deck pouring sequence typically involves the following steps: 1. Preparing the supporting superstructure: Trusses, floor beams, and support beams are fabricated and erected, and shear connectors are prepared on the top of the beams. 2. Placing the formwork: Formwork is placed on top of the beams to create a mold for the concrete deck. 3. Placing the reinforcement: Reinforcement, such as steel bars or mesh, is placed within the formwork to provide additional strength to the deck. 4. Pouring the concrete: Concrete is poured into the formwork and leveled to create a flat surface for the deck. 5. Finishing the surface: The surface of the concrete is finished with a trowel to create a smooth, even surface. 6. Curing the concrete: The concrete is left to cure, typically for several days, to gain strength and durability. 7. Applying the wearing surface: A final layer of asphalt or other wearing surface is applied to protect the concrete deck and provide a skid-resistant surface for vehicles. **Prior to the deck pouring stages**, confirm that the substructure elements (foundations, piers, pier caps, abutments) and the truss / floor-beam / support-beam system have been constructed. In some models the substructure is not modeled and fixed supports are used at bearing locations; in those cases ensure that the trusses, floor beams, and bracings have been constructed in previous stages, and that the formwork load has been applied upstream. For typically sized bridges, the **most common placement sequence** pours positive bending-moment regions first, followed by negative-moment zones. After the positive-moment regions have sufficiently cured (usually several days), the concrete in the negative-moment regions is poured to minimize deck cracking over the piers. ## Deck Casting **Pouring Stage (Weight Only):** At this stage, the deck load and haunch load are calculated and applied on top of the non-composite superstructure. It is crucial to differentiate between the deck hardening stage (composite) and the non-composite state load applications. During finite element analysis, the self-weight of shell elements is computed and distributed to the nearest beams/trusses. Consequently, the deck self-weight cannot be visualized graphically because it is applied during the load-vector generation phase of the FEA. The haunch load, however, is calculated in the library object and can be observed graphically in the FEA loading view. **Hardening Stage (Gains Stiffness):** During this stage, the deck shell elements gain stiffness and no load is applied. If no further loads are added during this stage, the results of the finite element analysis will remain unchanged because the sole modification is in the stiffness matrix. **Deck:** Choose the deck to define the pouring sequence for. **Start Skew:** Specifies the boundary of the deck pouring area at the start station, in addition to the start station defined under the Longitudinal tab. A skew value of 0 means the boundary line is perpendicular to the alignment. A positive value rotates that line clockwise; a negative value rotates it counterclockwise. **End Skew:** Specifies the boundary of the deck pouring area at the end station, in addition to the end station defined under the Longitudinal tab. A skew value of 0 means the boundary line is perpendicular to the alignment. A positive value rotates that line clockwise; a negative value rotates it counterclockwise. **Haunch Load \[Ignore/Include]:** If **Include** is selected, the haunch load is automatically computed and applied to the supporting beams in the selected pouring stage. The haunch load is computed from the unit weight of the deck material, the selected taper parameter for the overhang region, and the haunch thickness. If **Ignore** is selected, no haunch load is applied at this stage. **Self Weight Factor:** Multiplier applied to the computed deck self-weight at the pouring stage. Use this to account for sacrificial thickness or similar effects — for example, if the deck thickness for composite section properties is 8″ but the thickness used for weight calculation is 8.5″ (0.5″ sacrificial), enter `1.0625` (8.5″ / 8″). ## Longitudinal **Start Station:** Defines the boundary of the deck pouring area along the PGL with a specified start station. The value must be less than the deck end station and less than the **End Station** entered below. **End Station:** Defines the boundary of the deck pouring area along the PGL with a specified end station. ## Transverse **Transverse Const. Type \[Complete/Partial]:** Typically the deck pouring sequence does not require splitting the pour in the transverse direction and the **Complete** option is used. In some cases (e.g. rehabilitation projects, staged widenings) it may be necessary to pour only part of the deck width; select **Partial** and fill in the offset parameters below. **Left Offset Start (PGL):** When looking up-station along the alignment, the left transverse offset from PGL that defines the region at the start station. Applies only when **Transverse Const. Type** is **Partial**. **Right Offset Start (PGL):** When looking up-station along the alignment, the right transverse offset from PGL that defines the region at the start station. Applies only when **Transverse Const. Type** is **Partial**. **Left Offset End (PGL):** When looking up-station along the alignment, the left transverse offset from PGL that defines the region at the end station. Applies only when **Transverse Const. Type** is **Partial**. **Right Offset End (PGL):** When looking up-station along the alignment, the right transverse offset from PGL that defines the region at the end station. Applies only when **Transverse Const. Type** is **Partial**. ## Truss This group defines the deck-to-truss composite connection specific to the Truss Bridge workflow. Rigid links are generated between each listed truss insertion point and the closest deck edge, allowing the deck and the truss chords to act compositely once the deck hardens. **Truss Insertion Points:** Pick the [Insertion Point \[TB\]](/templates/truss-bridge-workflow/bridge-geometry-tb/insertion-point-tb.md) objects that locate the truss chords to be engaged with the deck. Rigid links are generated from each insertion point to the nearest deck boundary / corner. **Rigid Section:** Specify the section assigned to the rigid links between the truss insertion points and the deck. 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