The Impact/Dynamic Load Allowance window allows the user to enter the impact factors. Impact can be entered for a bridge, for a superstructure definition, and for a member alternative.
Impact/Dynamic Load allowance for creating new superstructure definitions and member alternatives:
The value specified for the bridge is used when a new superstructure definition is created. The value specified for the superstructure definition is used when a new member alternative is created.
Impact/Dynamic Load allowance for analysis:
The value used for an analysis is specified at the level of the analysis. For a member alternative, the value specified for the member alternative is used. For a superstructure definition analysis, the value specified for the superstructure definition is used for the superstructure definition and the value specified for the member alternatives is used for member alternatives.
If the impact for a bridge is changed, the impact for any existing superstructure definitions or member alternatives in that bridge is not changed correspondingly. Likewise, if the impact for a superstructure definition is changed, the impact for any existing member alternatives are not changed correspondingly.