Moving bridge load

This table allows the user to define loads which move along the structure. To apply these loads to the structure they have to be expanded using to Grid Point Loads using the Model > Bridge modelling > Expand bridge loading menu command.

All bridge loading defined in this table is defined relative to paths specified in the paths table. Note that once the load cases have been generated changes to this table or the data to which it refers will not affect the generated load. Each entry forms a series of load cases when expanded into grid point loads.

Definition

Name

The name is used as the basis of the load case title for the expanded bridge loads. The individual load cases are identified as title.1, title.2, etc.

Path

The path name to be loaded. A number of restrictions apply to combinations of path and load types:

Vehicle paths can only be loaded with vehicles.

Footway paths can only be loaded with KEL or UDL loads (to place accidental wheel loads on footways use the Generate static vehicle dialog.)

Lane and track paths can accept any loading.

If Bridge design loading code is selected in Bridge loading specification, the bridge analysis has to be done first, then the carriageways paths can be populated to the path dropdown list and the static bridge loads can be defined and expanded.

Load type

This can be one of the following:

• Moving vehicle – Vehicle as above positioned at successive intervals along the path. Each vehicle position appears in a separate load case.
• Moving KEL – A series of six grid point loads (or two point loads for tracks) will be generated to simulate a line load, equally spaced across the width of the path at the chainage specified, positioned at successive intervals along the path. The intensity of the KEL is the total line load. Each KEL appears in a separate load case. The KEL will always be placed normal to the alignment. To place a KEL at a skew the grid point loads will need to be modified after expansion.

Start and end chainage

Define first and last positions of the KEL or of the origin of the vehicle (normally the back axle) on the path.

Interval

The space between successive KEL or vehicle positions.

Vehicle

Selected from the standard and user defined vehicles.

Load Intensity / Load factor

Multiplier on vehicle wheel loads.

Magnitude of KEL (positive).