Refined Bridge Analysis offers three approaches for analytical modeling: grillage, offset girder, and finite element models. These create analytical models that better reflect the actual layout of the bridge girders. Alignments with plan curvature, skewed piers, and abutments are taken into account.
When performing Refined Bridge Analysis, it is important to understand that each model takes longer than the next to generate. Unless highly skewed or curved, the simpler Grillage model is sufficient for most analysis needs. FE - Offset Girder and more complex finite element models such as FE I-Plate girder will take significant amounts of time to generate the loading and solve.
Grillage is a two-dimensional analysis consisting of an interconnected series of beam elements that represent the major flexural members of a bridge superstructure.
The finite element analyses introduce additional elements such as bracing and stiffeners.