The South Road Bridge is part of the $620 million Darlington Upgrade design/build project which provides for the improvement of approximately 2 miles of one of the most important transit corridors in Adelaide, Australia. The bridge is 586 feet long and consists of three-span continuous twin curved steel tub-girders carrying a multi-use path as well as vehicular traffic over a major expressway. The design of the bridge is innovative in its use of double composite concrete construction, where the girder section over the piers acts compositely with the deck as well as with concrete poured in the bottom of the steel tub section to resist the negative bending moments. To minimize closure times on the expressway, the contractor chose to build the bridge in its entirety at a nearby site and move the bridge into place using self-propelled modular transporters (SPMT’s). In addition, to expedite the construction schedule the contractor requested to use 5’’ thick precast deck panels with a 5’’ thick concrete deck poured over the precast deck panels. Due to staging of the overall project, the bridge will be open to two lanes of traffic in a temporary condition, and in the final condition will carry one lane of traffic and a twelve-foot cycling/pedestrian path.
With span lengths of 235’, 219 ‘, 132’, the project architects chose to use concavely curved girders so that the structure lines would be smooth and pleasing. Girder depths over the piers are approximately twelve feet deep and approximately six feet deep over the abutments. The presentation will discuss the structural modeling of the bridge including construction staging and SPMT movements, design methodology differences between US and Australia Codes, and benefits and challenges of using double composite construction methods.
Construction Staging analysis including Self-Propelled Modular Transporter (SPMT) Sequence
Analysis for SPMT support settlements
Developing a bridge monitoring plan for the SPMT move from the Midas analysis