Live Load Case (Railroad) [SIG]

General

Influence Surface: The previously defined influence surface can be assigned to a specific live load case using this parameter.

Vehicle: Vehicles used in the Inf. Surface Analysis can either be imported or selected from previously defined options and assigned to specific live load cases using this parameter.

Impact Factor Comp. Method (Vertical Effect) [AREMA 1.5.3-c.1/AREMA 1.5.3-c.2a/AREMA 1.5.3-c.2b/User Defined]: Since impact factors may change depending on the chosen AREMA specification, users can specify the AREMA code for the impact factor to be calculated accordingly by selecting the given options for this parameter. Additionally, users can define the impact factor manually by setting this parameter to the option User Defined.

Impact Factor (Vertical Effect): This parameter can only be specified if the Impact Factor Comp. Method (Vertical Effect) parameter is defined with the option "User Defined"; otherwise, this parameter will be marked as Not Applicable (N/A).

Impact Factor Comp. Method (Rocking Effect) [No rocking effect/Downward on left rail/Downward on right rail/Most critical of all]:

This parameter specifies the method used to calculate the impact factor due to the rocking effect of trains traversing curves or transitions in the rail system. The options include:

• No Rocking Effect: This option indicates that the rocking effect is not considered in the impact factor calculations. It assumes that the vertical loads are static and do not include any additional dynamic forces due to rocking.

• Downward on Left Rail: This option accounts for the rocking effect when the center of gravity of the train shifts downward on the left rail during movement, increasing the vertical load on that rail. This condition is particularly relevant on left-hand curves, where lateral forces can cause the train to rock.

• Downward on Right Rail: Similar to the above, this option considers the rocking effect when the center of gravity shifts downward on the right rail. This is significant on right-hand curves, resulting in increased vertical loads on the right rail.

• Most Critical of All: This option allows for the selection of the most critical scenario among the other options. It automatically identifies which rocking condition (downward on the left rail or right rail) produces the maximum impact factor for design purposes, ensuring that the most conservative estimate is used for safety.

Impact Factor (Rocking Effect):

This parameter represents the calculated impact factor resulting from the rocking effect based on the selected Impact Factor Comp. Method. It quantifies the dynamic loading conditions imposed on the track and supporting structures due to the rocking motion of the train as it traverses curves.

• The impact factor can vary based on the selected method, reflecting the additional dynamic forces experienced during operation.

• It is crucial for ensuring that the railway infrastructure can accommodate both static and dynamic loading, providing a margin of safety against unexpected conditions such as excessive rocking.