Function
- Trace and graphically display the vehicle loading condition (corresponding moving load case and location) that results in the maximum/minimum stress of a beam element. The loading condition is converted into a static loading and produced as a model file of the MCT type. This is an extremely useful feature when we wish to find the loading condition that creates the maximum or minimum stress.
Call
From the main menu, select [Results] tab > [Type : Analysis result] > [Moving Load] group > [Moving Tracer] > [Beam Stresses]
Input
Beam Stresses dialog box
Moving Load Cases
Select a moving load case (vehicle type) that is to be traced and located at a position satisfying the max/min stress.
Key Element
Enter a beam element number. Use the mouse to select or directly enter the number.
Scale Factor
Enter the drawing scale factor for the influence line/surface. This does not affect the influence line/surface values.
Parts
Assign a position along the length of the beam element within which the internal stress influence is sought.
Components
Moving Load Tracer for stresses operates based on combined axial and flexural stresses. Thus a location in the section, where combined stress is of interest, is identified here.
1(-y, +z): Combined stress at location 1.
2(+y, +z): Combined stress at location 2.
3(+y, -z): Combined stress at location 3.
4(-y, -z): Combined stress at location 4.
Type of Display
Assign the type of display.
Display the contour of the influence line together with the vehicle loading condition.
Ranges: Define the contour ranges.
Customize Range...: Assign the color distribution range of contour. Using the function, specific colors for specific ranges can be assigned.
Number of Colors: Assign the number of colors to be included in the contour (select among 6, 12, 18, and 24 colors).
Colors: Assign or control the colors of the contour.
Color Table: Assign the type of Colors.
Customize Color Table...: Control the colors by zones in the contour.
Reverse Contour: Check on to reverse the sequence of color variation in the contour.
Contour Line: Assign the boundary line color of the contour.
Element Edge: Assign the color of element edges while displaying the contour.
Contour Options: Specify options for contour representation.
Contour Fill
Gradient Fill: Display color gradient (shading) in the contour.
Draw Contour Lines: Display color boundaries in the contour.
Draw Contour Line Only
Display only the colored boundaries of the contour.
Mono line: Display the boundaries of the contour in a mono color.
Contour Annotation
Legend or annotation signifying the ranges of the contour is displayed.
Spacing: Specify the spacing of the legend or annotation.
Coarse Contour(faster) (for large plate or solid model)
Represent a simplified contour for a large model using plate or solid elements to reduce the time required to represent a complete contour.
Extrude
Where plate elements or solid elements along a cutting plane are represented in contour, a three-dimensional contour is created. The positive direction of the analysis results is oriented in the z-axis direction of the local element coordinate system.
The option is not concurrently applicable with the Deformed Shape option. Similarly, the option cannot be concurrently applied to the cases where the Hidden option is used to display plate element thicknesses or the Both option is used to represent Top & Bottom member forces (stresses).
Display various references related to analysis results to the right or left of the working window.
Legend Position: Position of the legend in the display window.
Rank Value Type: Specify the output format and decimal places for the Legend values.
Graphically display the vehicle load condition for which the analysis results in the max/min stress.
Set the detailed display condition for the vehicle load case.
Load Scale Factor: Enter the drawing scale factor for the load representation.
Load Value: Option to display the load values.
Reflect the impact factor in the display.
This is a display option that does not affect the results but allows users to see the Moving Tracer with and without the Psi factors applied for relevant loads, This option is related to Moving Load Cases with Ignore Psi Factor option checked off and will have no effect on Load Cases with Ignore Factor checked on.
Maximum Value
Produce the maximum or minimum value calculated from the moving vehicle load analysis.
Write Min/Max Load to File: Where Influence Line or Influence Surface analysis has been carried out, the moving load case, which produces the maximum or minimum results, is converted into a static loading and produced as an MCT type.
Moving Load Converted to Static Load
Export coincidental centrifugal, acceleration & braking forces according to the Eurocode and British Standards (BD 21/01 & BD 86/11).
Import vertical, centrifugal (C), acceleration(Longgitudinal-AA & Transverse-AL), and braking(Longitudinal-BA & Transverse-BL) as different static load Cases.
The applicable horizontal loads are shown in the table below.
| Code | Moving Load | Centrifugal | Accel./Brake, longitudinal |
Accel./Brake, transversal |
|
| Eurocode | LOAD MODEL 1 | O | O | O | |
| LOAD MODEL 3(UK NA) | O | O | - | ||
| LOAD MODEL 3 | - | - | - | ||
| Load Model 71 | O | O | - | ||
| LOAD MODEL SW/0 | O | O | - | ||
| LOAD MODEL SW/2 | O | O | - | ||
| UNLOADED TRAIN | - | - | - | ||
| HSLM A | - | O | - | ||
| HSLM B | - | O | - | ||
| BD 21/01 | HA | HA Only | O | - | - |
| HA & HB | O | - | - | ||
| HA & HB(Auto) | O | - | - | ||
| BD 86/11 | SV | O | O | - | |
| SV TRAIN | O | O | - | ||
| SOV | - | O | - | ||
Vertical Loads - Check on to export vertical vehicular loading.
Centrifugal Forces - Check on to export centrifugal forces (horizontal) due to vehicular loading.
Braking and Acceleration Force - Check on to export braking and acceleration forces (horizontal) due to vehicular loading.
Additional Data
Height of Centrifugal Force from Carriageway Level(Eurocode Only) - Vertical distance between the element/node to the application of centrifugal force.
Maximum Speed - Maximum vehicular speed.
Horizontal Radius - Horizontal radius of curvature of the bridge.
Direction of Centrifugal Forces with reference to Vehicle Direction - Select the direction of centrifugal forces in the transverse direction of a lane based on the longitudinal direction of a lane
Right-to-Left Direction
Left-to-Right Direction
Example of centrifugal forces direction
Provided design codes
EN1991-2 4.4.2 / UK NA EN 1991-2 NA.2.18 / EN 1991-1 6.5.3 / BD21 Centrifugal Effects / BD86 Centrifugal Effects / BD86 Longitudinal Loading
Export coincidental centrifugal, acceleration & braking forces according to the AASHTO LRFD standard. Import vertical, centrifugal (C), acceleration(AA), and braking(BA) as different static load Cases. The applicable horizontal loads are shown in the table below.
| Moving Load Code | Standard |
| AASHTO LRFD | AASHTO LRFD Load |
| AASHTO Standard Load | |
| AASHTO Legal/Permit Load | |
| IADOT Load | |
| ILDOT Load | |
| LADOT Load | |
| MODOT Load | |
| OHDOT Load | |
| RIDOT Load | |
| VADOT Load | |
| WIDOT Load | |
| Caltrans Standard Load (2017_draft) | |
| Caltrans Standard Load | |
| Others | |
| User Defined | |
| PennDOT | PennDOT Load |
| Others | |
| User Defined |
Acceleration and braking force can be obtainable for all the vehicle types within the standard specified above. However, the centrifugal force will only be available for the vehicle containing a concentrated load
Vertical Loads - Check on to export vertical vehicular loading.
Centrifugal Forces - Check on to export centrifugal forces (horizontal) due to vehicular loading.
Braking and Acceleration Force - Check on to export braking and acceleration forces (horizontal) due to vehicular loading.
Additional Data
Design Speed - Design speed.
Radius of Curvature - Horizontal radius of curvature of the bridge.
Factor for Centrifugal Force - 4/3 for load combinations other than fatigue and 1.0 for fatigue
Direction of Centrifugal Forces with reference to Vehicle Direction - Select the direction of centrifugal forces in the transverse direction of a lane based on the longitudinal direction of a lane
Right-to-Left Direction
Left-to-Right Direction
Example of centrifugal forces direction
The centrifugal force shall be calculated as per AASHTO LRFD 3.6.3:
C = f v^2/gR
where:
v = highway design speed (ft/s)
f = 4/3 for load combination other than fatigue and 1.0 for fatigue
g = gravitational acceleration: 32.2 (ft/s^2)
R = radius of curvature of traffic lane (ft)
C value will be applied to the axle load to calculate centrifugal force.
The braking force shall be taken as the greater of:
25 % of the axle weights of the design truck or tandem.
5 % of the (design truck + lane load) or 5 % of the (design tandem + lane load).
* The multiple presence factors shall apply.
* Dynamic Load Allowance shall not be considered.
* Direction of acceleration will be the same as the vehicle moving direction and the direction of braking will be the opposite.
Detailed Results
Produce Produces a text file detailing the calculation of HA Lane Factors for the current moving load tracer. The report will apply different factors depending on the type of HA vehicle defined and the options chosen by the user as explained below.
HA Lane Factor: BD 37/01 – Lane factors (LF) computed as described in clause BD37/01 Table 14 with adjustment factor (AF) and reduction factor (K) set to 1.
HA Lane Factor: BD 21/01 – Lane factor (LF) applied as given in clause BD21/01 5.24 with adjustment factor (AF) and reduction factor (K) set to 1 as default. If the Additional Data option is checked on in the vehicle definition, the values of adjustment factor (AF) and reduction factor will be computed according to clause BD21/01 5.23 and Figure 5.2 to 5.7 respectively.
HA Lane Factor: User-defined – Lane factors (LF) are at default as given in clause BD21/01 5.24 unless modified with adjustment factor (AF) and reduction factor (K) set to 1 as default. If the Additional Data option is checked on in the vehicle definition, the values of adjustment factor (AF) and reduction factor (K) will be computed according to clause BD21/01 5.23 and Figure 5.2 to 5.7 respectively.
Revision of Civil 2014
Auto-generation of centrifugal forces as per EN1991-2:2003
Centrifugal force due to vehicle load in the horizontally curved bridge can be generated as a static load by selecting "Centrifugal Forces" option.
The following vehicle types are supported:
Road Bridge: Load Model 1 Standard and user-defined vehicle
Railway Bridge: Standard Vehicle – LM71, SW/0, SW/2, Unloaded Train
User Defined Vehicle – LM71, SW/0, SW/2, Unloaded Train
Characteristic values of centrifugal forces are automatically calculated as per EN1991-2:2003, clauses 4.4.2 and 6.5.1.
File Name
Enter the file path and name of the MCT file to be output.