Augustine Bridge Work Wins 2014 Construction Excellence Award.
Baltimore, MD – The DelDOT Augustine Cut-off (Bridge 1-585) rehabilitation project was awarded the Delaware Contractor’s Association 2014 Construction Excellence Award for the category of Bridge Restoration under $5 Million. Bridge 1-585 contains a fracture critical pin and hanger assembly which, prompted by the 2007 collapse of the I-35W bridge in Minneapolis with a similar design, DelDOT wanted to retrofit. Pin and hanger connection details were more widely used in older bridges for several reasons including:
- It simplified analysis, which at the time was performed by hand without the aid of computers.
- It avoided corrosion by reducing the number of deck joints and moving the necessary joints away from the bearings.
A pin and hanger assembly joins two separate girder segments with one pin in each girder, connected by a hanger rod or plate. This detail is fracture critical, meaning it is non-redundant. Failure of this component could cause part or all of the bridge to collapse. Advances in construction and design are why technology pin and hanger assemblies are no longer used on new bridges. WR&A designed a “load sharing” system of tensioned hanger rods to 20% of the bridge dead load, thereby reducing the load carried by the pin and hanger. To prevent collapse, the retrofit was designed to carry the entire bridge, dead and live load, in the event of a failure of the pin and hanger. Additional maintenance performed during the rehabilitation included a new polyester polymer concrete (PCC) deck overlay, bridge joint repairs and replacement, structural steel repairs, cleaning and painting of the structural steel, and replacement of bridge fencing and sidewalk repairs. The total cost of the project was $4,918,606.