Traffic Surface Lanes

Add
To enter new or additional traffic surface lanes

Modify

To modify previously entered traffic surface lanes

Select a Lane Name for which lane information is to be modified.

Delete

To delete previously entered traffic surface lanes

Select a Lane Name for which lane information is to be deleted.

Copy

To copy previously entered traffic surface lanes

Select a Lane Name for which lane information is to be copied.

Lane Name

Enter the name of a traffic surface lane.

Traffic Lane Properties

Lane Width

Enter the width of a traffic surface lane.

Wheel Spacing

Enter the spacing between the wheels. For influence line analysis, the program automatically applies a load equal to "load ÷ of wheels" to each wheel.

Truck Load                                                          Lane Load

For influence line analysis, Uniform Lane Load is loaded to each wheel as a uniform line load, which is the load per unit length divided by no. of wheels. For influence surface analysis, Uniform Lane Loads are applied as uniform area loads acting on the traffic lane surface.

For influence line analysis, Concentrated Lane Load divided by no. of wheels is applied to each wheel. Concentrated Lane Load needs to be applied as a uniform line load perpendicular to the traffic line lane, but this is not supported in influence line analysis using beam elements. For influence surface analysis using plate elements, Concentrated Lane Load divided by no. of wheels is applied to each wheel. Applying Concentrated Lane Load as a uniform line load is currently not available.

Offset Distance to lane center

Enter the distance from the line of traffic lane nodes to the center of the traffic surface lane. Viewing towards the moving direction of the traffic surface lane, a positive eccentricity (+) refers to an offset to the right from the traffic lane nodes and a negative eccentricity (-) refers to an offset to the left from the traffic lane nodes.

Impact Factor

Enter the impact factor for the entered traffic surface lane being defined.

Skew

Enter the skewed angles at the start and end of the bridge referring to the diagram.

Eccentricity of Vertical Load to consider Cant

The eccentricity of loading with respect to the center-line of the track.

The effect of cant, relative vertical distance between the uppermost surface of the two rails at a particular location along the track may be considered by taking the eccentricity of loading with respect to the center-line of the track, which will result in the increase in the wheel load on the inside of the curve and a concomitant decrease in the outside wheel load.

The wheel load reactions, RL and RR are calculated by summing moments about Point O and enforcing equilibrium.

If the slope is 5%, (s = 2.0m, h = 2.0m)

Figure 1. Effects of cant of the wheel load reactions

This can be simulated by applying the eccentricity of vertical loads. In the above case, the associated eccentricity can be calculated by summing moments about the center of gravity as follows:

Figure 2. Eccentricity of vertical loads

Centrifugal Force

Left Wheel of Vehicle Moving Forward

Enter the input value for the left wheel of vehicle moving in forward direction that need to be considered to simulate the overturning effect in terms of multiplication factor to the total load of the axle (W).

As per the entered value the program would automatically calculate the corresponding factor for the right wheel of forward direction and both wheels of backward direction. The results of vehicle application will be the combination of vertical effect and overturning effect of the vehicle. The overturning component causes the exterior wheel line to apply more than half the weight of the truck and the interior wheel line to apply less than half the weight of the truck by the same amount.

 This option is only available if AASHTO LRFD is selected as Moving Load Code.

Traffic Lane Properties (France code only)

· Load System (A or B)

Loadable Width : Enter the carriageway width.

Load System A

Load System Bc

Load System Bt

Number of Lanes

Enter the maximum number of lanes. When the maximum numbers of lanes are different between Load System A and B, create the lanes for Load System A and B separately. The program will generate the individual lanes within the loadable width based on the lane width of Load System A and B specified by the French code. The lanes will be placed to find the most critical effects for each component of forces of the elements. The loads will be applied only in the unfavorable parts of the influence line, longitudinally and transversally.

Offset Distance to lane center

Enter the distance from the line of traffic lane nodes to the center of the traffic surface lane. Viewing towards the moving direction of the traffic surface lane, a positive eccentricity (+) refers to an offset to the right from the traffic lane nodes and a negative eccentricity (-) refers to an offset to the left from the traffic lane nodes.

Skew

Enter the skewed angles at the start and end of the bridge referring to the diagram.

Dynamic Factor

Enter the span length, L and the span weight, G to determine dynamic factors for the traffic line lane elements. For the continuous bridges, when the span length and weight are different between spans, enter the values of L and G for each span separately. The value of S, the maximum total weight of the axles of system B that can be placed on the deck of the span, will be determined by the program. The option for the application of the dynamic factor can be selected from the definition of vehicles. The dynamic factors calculated by the program can be viewed from the Detail Result in the Moving Load Tracer.

Centrifugal Force

Left Wheel of Vehicle Moving Forward

Enter the input value for the left wheel of vehicle moving in forward direction that need to be considered to simulate the overturning effect caused by centrifugal forces in terms of multiplication factor to the total load of the axle (W).

As per the entered value the program would automatically calculate the corresponding factor for the right wheel of forward direction and both wheels of backward direction. The results of vehicle application will be the combination of vertical effect and overturning effect of the vehicle. The overturning component causes the exterior wheel line to apply more than half the weight of the truck and the interior wheel line to apply less than half by the same amount.

 The bridge class can be defined from the Analysis>Moving Load Analysis Control Data dialog box.

· Military / Sidewalk / Pedestrian

Loadable Width

Enter the width of an individual lane, which should be larger than the width of the military vehicles. Number of lanes is fixed as one. These load types can only be applied to one lane.

The minimum loadable width for each vehicle:

Convoy Mc 80: 3.65m, Convoy Mc 120: 4.30m,
Convoy Me 80: 3.50m, Convoy Me 120: 4.00m,
Convoy Type D: 3.30m, Convoy Type E: 3.30m

Convoy Mc 8

Convoy Me 80

Offset Distance to lane center
Enter the distance from the line of traffic lane nodes to the center of the traffic surface lane. Viewing towards the moving direction of the traffic surface lane, a positive eccentricity (+) refers to an offset to the right from the traffic lane nodes and a negative eccentricity (-) refers to an offset to the left from the traffic lane nodes.

Skew
Enter the skewed angles at the start and end of the bridge referring to the diagram.

Dynamic Factor

Enter the span length, L and the span weight, G to determine dynamic factors for the traffic line lane elements. For the continuous bridges, when the span length and weight are different between spans, enter the values of L and G for each span separately. The value of S, the maximum total weight of the axles of the vehicle that can be placed on the deck of the span, will be determined by the program. The option for the application of the dynamic factor can be selected from the definition of vehicles. The dynamic factors calculated by the program can be viewed from the Detail Result in the Moving Load Tracer.

 The bridge class can be defined from the Analysis>Moving Load Analysis Control Data dialog box.

Moving Direction

Define the direction of the vehicular loading.

Forward : consider only the direction from the start to end.

Backward : consider only the direction from the end to start.

Both : consider both vehicular loading direction.

Supported Code : AASHTO standard, AASHTO LRFD, PENNDOT, Canada, Australia, Korea, KSCE-LSD15, India, Taiwan

Unsupported Code : BS, EUROCODE, Russia, China

Selection by

Specify the method of defining a traffic lane node line to define a traffic surface lane.

2 points

Use the coordinates of two points to enter a traffic lane node line.

All the nodes connecting these two points constitute a traffic lane node line.

Picking / Number

Select all the nodes along the traffic lane node line.

Use the mouse or directly enter the node numbers to create a traffic lane node line.

The traffic surface lane is defined by the traffic lane node line, eccentricity and traffic lane width. The traffic surface lane is created by placing the traffic lane center offset by an eccentricity distance from the traffic lane node line. Extending 1/2 of the lane width on both sides of the lane center while looking towards the moving direction defines the traffic surface lane.

Operations

Entry is reflected when Selection by Number is used.

Add : Add selected nodes to the traffic lane node line.

Insert : Insert selected nodes to become a part of the previously entered traffic lane node line.

Delete : Delete selected nodes from the traffic lane node line.

Span Start

For multi-span bridges, select the starting element of each span to distinguish spans. This is used to calculate the maximum negative moment of a continuous bridge due to DL.