Construction Moving Load [SIG]
The Construction Moving Load feature allows users to define live loads that occur during deck construction. Its purpose is to generate moving loads due to finishing machine, and live load by inputting a few parameters. Users can specify the number of positions for the finishing machine, and loads will be generated automatically over the girders with even spacing. The envelope for these positions is created automatically, enabling users to view critical loading values for each girder without needing to define a result extraction case.
When modeling with sequential deck pouring, if the deck is poured in multiple stages over the selected girders, using a single construction live load is sufficient for the those girders. This can be accounted for during the result extraction process. For non-composite dead loads, critical loading must be identified using the Envelope option across all construction stages prior to reaching the composite state (Figure 1a). These loads are then combined in the limit state with the automatically generated result extraction from the construction live load (Figure 1b).
General
Stage: Choose the stage at which to apply the construction live load. Note that analysis results cannot be visualized within this stage after the analysis is complete. OpenBrIM automatically generates sub-stages and assigns the selected stage as the prior stage, so analysis results will be presented in these sub-stages.
Left Exterior Girder: Specify the left exterior girder in the direction of the PGL
Right Exterior Girder: Specify the right exterior girder in the direction of the PGL.
Loadings will be generated between the left and right exterior girders.
Specify Position as[Number of Positions/Station List]: This parameter determines how the position is specified.
Number of Positions: Specify the number of load placements centered along the girder length for the finishing machine. The minimum number of positions allowed by the software is two. These loads are created as sub-stages by OpenBrIM and placed along the length of the girders.
Station List: This parameter is used to organize the list of stations. Please note that the station is measured along the PGL. The Moving Load is centered between the left and right exterior girder lines. Therefore, the station input must be entered accordingly, as shown in the image below.
Moving Loads
Moving Point Load (Exterior Girders): Specify the magnitude of the point load to be applied to the exterior girders. This load can represent the loading in Section 2.13.1 Category A of the FDOT Structures Manual 2024 (Figure 3).
Point Load Distance to Exterior Girder: Specify the eccentricity of the point load from the center of the top flange of the nearest exterior girder.
For Steel I-Girders: Measure the distance from the centerline of the top flange to the line load.
For Tub Girders: Measure the distance from the centerline of the exterior flange to the line load.
Moving Line Load (Exterior Girders): Specify the magnitude of the line load to be applied to the exterior girders. This load can represent the loading in Section 2.13.1 Category D of the FDOT Structures Manual 2024 (Figure 4).
Line Load Distance to Exterior Girder: Specify the horizontal distance (eccentricity) between the line load and the exterior flange of the nearest exterior girder:
For Steel I-Girders: Measure the distance from the centerline of the top flange to the line load.
For Tub Girders: Measure the distance from the centerline of the exterior flange to the line load.
Line Load Length: Specify the length of the line load.
Moving Surface Load (All Girders): Specify the magnitude of the surface load applied to both the exterior girders and the interior girders. The load is centered between the selected two girders. This load can represent the loading in Section 2.13.1 Category B of the FDOT Structures Manual 2024 (Figure 4).
Surface Load Length (Longitudinal Direction): Specify the length of the surface along the PGL.
Surface Load Width (Transverse Direction): Specify the width of the surface, which is perpendicular to the PGL.
Static Loads
Static Surface Load (Exterior Girders): Specify the magnitude of the static surface load applied only to the exterior girders. This loading is not a moving load, meaning it remains constant across all automatically generated sub-stages. For tub girders, the load is applied to the exterior flanges of the selected girders. This load can represent the loading in Section 2.13.1 Category C of the FDOT Structures Manual 2024 (Figure 4).
Static Surface Load Width (Transverse Direction): Specify the width of the static surface load. Since the length of the static surface load is predefined along the girder, no input is necessary for the longitudinal direction.
Distance from the Surface Load Center to the Exterior Girder: Specify the horizontal distance (eccentricity) between the center of the surface load and the exterior flange centerline of the nearest exterior girder:
For Steel I-Girders: Measure the distance from the centerline of the top flange to the center of the surface load.
For Tub Girders: Measure the distance from the centerline of the exterior flange to the center of the surface load.
This parameter is used to compute the moment generated by the surface load.
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