Skip to main content

Path Loading

Path Loading can be used with the results of an influence line analysis to derive optimized bridge loading load cases.

Definition​

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 using Variable Loads (to place accidental wheel loads on footways use the Generate Static Vehicle dialog.)

Lane and Track paths can accept any loading.

Load Type

A number of standard path loadings implement the requirements of specific design codes.

The user can define other loading which consists of one of the following:

  • User Vehicle: any standard or user defined vehicle on its own.

  • User Vehicle + variable load: any standard or user defined vehicle combined with any standard or user defined variable load. An exclusion length can be specified, see below.

  • User variable load: any standard or user defined variable load (UDL and KEL).

  • EC1:LM3 Generic: any standard or user defined vehicle, combined with a UDL outside the exclusion length (see below) and a second vehicle placed within the UDL in accordance with EN 1991-2 (EC1). Note that UDL in GSBridge is defined as kN/m/lane, while UDL in EC1 is defined in kN/m².

The components of the Standard loading can be factored independently (to allow for 25 units of HB for example). Note that the VUDL factor specified for variable loading is applied to both UDL and KEL.

Variable Load

Details of the Variable loads (UDL and KEL) are defined in the variable load module. The factor can be used to modify the intensity of standard variable loads (to allow for lane factors). A knife edge load (KEL) of the intensity specified in the variable load definition be placed at one point only on the lane.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 optimisation and expansion.

Standard footway loading intensity is for a unit width footway and the factor is the footway width (modified by reduction factors for wide footways).

UDL(1kN) is a 1kN/m/lane UDL which can be factored to give any intensity of constant UDL.

Vehicle

Details of the Vehicles are defined in the Vehicle module and referred to here.

The factor can be used to modify the intensity of standard Vehicles (for example to reduce the standard 45 unit HB vehicle to a lower intensity).

The exclusion length is measured from the midpoint of the vehicle to the point where the VUDL starts on either side of the vehicle (so an exclusion length of 0 gives an uninterrupted VUDL).

Note: As the number of analysis cases in the bridge analysis task depends on path loading data, the editing of path loading will be disabled if there is a bridge analysis task.