NZ - Fatigue Vehicle
Description
This form is used to define the location of the standard TT530 fatigue loading model in accordance with the New Zealand Transport Agency (NZTA) Bridge Manual Cl 3.2.6. Various options are available within the form for positioning the fatigue vehicle. 'Axle 1' is indicated by wheels with red circles.
Outline Procedure
This basic load case definition form is accessed from the Structure Loads Group Button in the Explorer Navigation Pane as described in Structure Loads.
Select the required carriageway and load element configuration, which will become highlighted in the display.
Position the fatigue vehicle arbitrarily on the deck by clicking with the mouse in the drawing area, and then drag it to the place where the vehicle is to be positioned, and click a second time. Two mouse clicks are thus required, the first draws the initial approximate position of the vehicle. This will move as the mouse is moved, until the mouse is clicked a second time. Various fields are updated as the vehicle is moved. A warning is issued if the vehicle is being located with reference to a footway.
The direction of the vehicle may be reversed by clicking on the Direction button.
Special Mouse Actions
The vehicle will move with the mouse between the first and second clicks. The movement will be confined to the nearest load lane and the position of the vehicle relative to the mouse is governed by the relevant fields. Subsequent clicks will pick-up and reposition the vehicle respectively.
Form Graphic
Field Help
Axle Load
Bogie Spacing
Not editable.
Easting
Northing
Bearing
The location of a vehicle is defined by the coordinates of a single point of the vehicle, and the bearing of the lines of the wheel tracks (from front axle to rear axle) measured anti-clockwise from the east direction in degrees. The point on the vehicle used for locating it may be varied using other fields on this form.
Dynamic Load Factor
Enter the dynamic amplification factor according to NZTA Bridge Manual Clause 3.2.6. The standard factor is 1.0, but enter as 1.3 within 6m of expansion joints or other discontinuities (including the ends of integral bridges) according to 3.2.6(c). A warning is issued if the value entered is outside the range 1.0 to 1.3.
Carriageway
Specify the carriageway and the load element configuration to which the vehicle is to be applied. The selected carriageway is shown highlighted on the display.
Position
The vehicle may be positioned within a lane, straddling lanes, or at any arbitrary position within the deck according to the selection made from this field.
Offset
The vehicle location will be transformed in a direction perpendicular to the line of the carriageway by the amount entered in this field.
Using
When the mouse is used to position the vehicle on the bridge deck, the vehicle position is defined by a single point which is taken as the intersection of the centreline of the vehicle with a perpendicular line corresponding to the selection made in this field. The vehicle centre and quarter points are derived from the distance between the first and last axles. 'Axle 1' is indicated by wheels with a red border.
Chainage
This field displays the chainage of the point defining the vehicle position measured along the Design Line for the selected carriageway. If the vehicle is not on the carriageway, there is no associated Design Line, and hence the chainage will not be updated. The position of the vehicle may be altered by entering a value in this field.
Axles
This field enables relieving axles to be excluded using the Axles Included sub-form. If the vehicle has been created by an influence surface analysis, excluded axles will already have been defined. The wheels of excluded axles are indicated on the display by hollow circles. Select 'Defined' to include or exclude the individual axles. Select 'All included' to include all axles.
Name
The program generates a short name that is used for identifying the loading case.
The default name may be changed by entering an alternative name in this field.
Direction
The direction of the vehicle may be reversed by clicking on this button.