While this tutorial was developed for the SAP2000 bridge modeler, the concept also applies to CSiBridge.

Key modeling steps


Consider a two-span bridge with two 15m long spans. The deck superstructure consists of four steel girders supporting a cast-in-place slab. Total superstructure width is 12m, girder spacing is 3m, and the overhang on each side is 1.5m.

These specifications may be defined as shown in Figure 1:



For the second span, the width linearly increases from 12m to 15m. Uniform flare and one-sided flare will be considered.

Uniform flare

Girder spacing increases from 3m to 4m. The structure is symmetric about the layout line. This may be modeled as follows:


One-sided flare

Girder spacing increases from 3m to 4m, while for both spans, the right edge of the bridge is straight. This may be modeled by assigning, in addition to the parametric variations for uniform flare, the following: