Dynamic Analysis in RM Bridge is a significant feature that allows OpenBridge Designer users to perform dynamic analyses within the schedule, together with static analyses, on the same model, and following the active construction stage.
As there is not much additional modeling effort it's more an engineering know-how and a computational processing power issue. With the latest advancements in laptop processors' speeds and capacity, most of the previous long analyses can now be performed in only minutes or hours, even within a usual machine available in any engineering office.
The model dynamics depend on three major aspects:
The most well-known restriction is due to the lumped mass matrix: as the masses are not distributed, as in reality; but, are considered concentrated in the nodes this requires a sufficiently fine subdivision of the structural parts into elements. Though the usual 1/10 of the span for static analysis is normally good enough also for dynamics, only piers might require special attention to their subdivision requirements. The usual natural frequencies analysis is performed and including non-linearities is also possible. For bridge structures currently four main areas are usually considered suitable to be more affected by structural dynamics :
For earthquake analysis two possible dynamic analyses are available: