The geometry was extremely difficult due to the “non-defined” parabolic curve of the existing arch. This existing structure had to replicated (digitally) in order to get a sense of the overall bridge geometry.
The existing parabolic arch box girders and existing splice conditions were all being strengthened by adding plates and replacing rivets with bolts, but all of the lateral bracing and chevron truss frames were being replaced, re-using existing connections on the parabolic box girders.
Had to recreate the 3D model of the existing bridge based off the 60 or 70-year- old prints.
The model was checked by the contractor against a 3D scan of the existing structure, using a “point cloud”. Thanks to Advance Steel, Weaver Bridge Corporation (WBC) was able to compare their model with the point cloud and all critical dimensions were verified. The model was within 1/8″ to 1/4″ of the point cloud at all critical “control” points, and all frames erected without a single misfit.
For this particular project, the existing shop drawings for the existing box girders were built to a “non-defined” parabolic arch.
Therefore, nothing could really be calculated. The only way WBC was able to have an accurate model was to create a 3D model, using the old shop prints. With Autodesk Advance Steel, they
were able to extrude a polyline along all of the offset dimensions and extrude a vertical plate that represented the workline of the box girders. WBC was then able to build the box girder around this “control” curve.
Another valuable feature was being able to create the DXF and NC files from the model for the complicated connections, after we were able to ensure it was a good match to the point cloud.
A model that had an amazing degree of accuracy as compared to what the field conditions indicated.
Able to keep the schedule and frames were released on time.
Not a single call from the field for any “fit” issues.
“This project was one of the most complex geometric projects that we have participated in and I truly believe that it would have been impossible without Autodesk Advance Steel. It allowed us to extrude a plate along a polyline that was developed from offset dimensions. We were not restricted to only being able to extrude along a ‘radiused’ polyline. Very powerful advantage when working with bridge girders.”
Douglas J. Weaver, NISD Senior Bridge