Overview

The midas model is for a multi-channel prestressed girders bridge 30 ft span and 24.75 ft width. The bridge is composed of 9-channel prestressed girders placed side by side. The bridge was modeled with frame elements for the girder's webs and plate elements for the girder's flange. Bridge dimensions and midas models are shown below.

The previous article (Curvature effects on a medium-span curved bridge) showed that we should be cautious to get reasonable torsional moments through simple beam analysis. One of the easiest ways to refine the results is to add more nodes at the inner support locations, however, we still have a question about “how many?”. Now we are reviewing the effect of curvature for bending moments. 
We are trying to find bending moments for three spans continuous curved girder, 150
ft + 223 ft + 150 ft = 523 ft, the radius is 1182’-6” as shown.

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A complex bridge is one of the most common engineering projects nowadays. This category of structures includes movable, cable-stayed, segmental concrete, and other bridges with unusual characteristics. These types of structures will require specialized expertise to design and build. One of our Expert Engineers, Yazeed Abuhassan, a Structural Design Engineer from Bergmann PC, shared his tips about designing a complex bridge.

One tip that could be useful to many is how he usually model the deck as an eccentric deck plate for moving load distribution purposes (creating an influence surface) without having to perform a beam/deck plate cut diagram to view the true moments in the composite girders.