Use the Define menu > Bridge Loads commands to specify lanes, vehicle loads and classes, and bridge responses to enable moving-load analysis of bridge structures. Unlike the commands on the Bridge menu, the subcommands of the Define menu > Bridge Loads command can be used without an additional license (i.e., the Bridge Modeler license is not required). Generally, the process requires creating the following definitions:
Lanes are defined and then frame objects are assigned to the defined lanes.
Vehicles loads are defined and then the defined loads are added to one or more vehicle classes.
The bridge response is defined, which specifies what information is calculated for joints and frame objects, thereby controlling the complexity of, and thus the time required to complete, the analysis.
The defined lanes, vehicle loads, vehicle classes, and bridge response are then used in defining a Moving Load analysis case.
Use the following Define menu > Bridge Loads subcommands to prepare for the analysis:
Lanes. Use the Define menu > Bridge Loads > Lanes command to define lanes that describe how vehicles move on the structure. A lane can be defined as a chain of frame objects, with an optional centerline offset if the vehicles are located to one side or the other of the frame object. Click the Define menu > Bridge Loads > Lanes command to access the Define Lanes form.
Vehicles. Use the Define menu > Bridge Loads > Vehicles command to define Vehicle loads. Click the Define menu > Bridge Loads > Vehicles command to access the Define Vehicles form. After defining vehicles, they must be added to one or more Vehicle Classes before they can be assigned to lanes in a moving-load analysis case, even if a Vehicle Class contains only a single vehicle.
Vehicle Classes. Use the Define menu > Bridge Loads > Vehicle Classes command to specify sets of one or more vehicles that can be assigned to act on lanes in a moving-load analysis case. Click the Define menu > Bridge Loads > Vehicle Classes command to access the Define Vehicle Classes form. Only one vehicle in a class acts on the lane at a time. Results are reported for the vehicle causing the most severe response.
Bridge Responses. Use the Define menu > Bridge Loads > Bridge Responses command to selectively control what information is calculated for joints and frame objects in the computationally intensive moving-load analysis. This command is useful in modifying the time required to complete the analysis. Click the Define menu > Bridge Loads > Bridge Responses command to access the Bridge Response Requests form. Use that form to specify the response categories to be analyzed and the calculation method to be used.
Example: Definition of Lanes,Vehicle Classes, Vehicles and a Bridge Response is demonstrated in Problem R.
See Also