# Parametrics in Bridge Design (CABD)¶

To easily generate any bridge system with reference to a corresponding alignment, the system input, e.g. the road axis, can be stored as a reference. The reference axis can be defined graphically with the input of its alignment elements in plan and elevation, or it can be derived directly from an AutoCAD object. By separating the geometry and the structure, i.e. geometric axes and structural model of the bridge, any changes to the geometric parameters can be implemented quickly and easily into a new calculation model.

Special points (so-called placements) can be defined along a defined axis with further corresponding information about dependencies, such as construction joints, cross members and support location. The variation of the bridge cross section along its length can be done by assigning variables along the axis.

For example, using these variables, complex cross section variations and effective widths can be defined. Depending on the type of setting and the number of data points, quadratic and cubic variations can be created.

For creating the FE model, structural elements can be defined along the defined axis and at placements, which are then linked to the finite element mesh.

The definition of prestressing tendons and the arrangement of traffic loads can also be defined relative to an axis, and thus be made independent of the structure.