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The Pacific Street Bridge over I-680 in Omaha, Nebraska was built as a replacement to an existing bridge due to the deteriorating condition and substandard width of its superstructure. The old bridge was 74 ft (22.6 m) wide and had four spans that are 44 ft 6 in. (13.6 m), 73 ft (22.3 m), 73 ft 6 in. (22.4 m), and 30 ft (9.2 m) long. Each span consisted of 11 steel I-girders at 7 ft (2.1 m) spacing. The new Pacific Street Bridge consists of two identical spans, 98 ft (29.9 m) long each with 17 degree skew angle. The bridge has six traffic lanes with a total width of 105 ft 8 in. (32.2 m).
The bridge superstructure consisted of twenty NU900 I-girders (ten for each span) that are 35.4 in. (900 mm) deep and spaced at 10 ft 8 in. (3.3 m). Each girder has a specified 28-day compressive strength of 10,000 psi (69 MPa) and pre-tensioned using 30-0.7 in. (17.8 mm) diameter strands. The 8 in. (203 mm) thick cast-in-place concrete deck has a specified 28-day compressive strength of 5,000 psi (34.5 MPa) and post-tensioned using 36-0.6 in. (15.2 mm) diameter mono strands in the longitudinal direction.
Precast concrete is the perfect solution for the Pacific Street Bridge over I-680 in Omaha, Nebraska. Precast concrete offers numerous benefits to this project, including increased safety, reduced construction time, and improved durability. Safety is improved because precast concrete pieces are already complete when delivered to the construction site. This means fewer on-site workers, reducing the potential for accidents. Construction time is reduced because the precast concrete pieces are assembled off-site and ready for installation, cutting out the time it would take to cast concrete in place.
Durability is improved because precast concrete is designed to last longer and withstand the elements better than traditional concrete. Additionally, precast concrete is designed to meet specific strength and durability requirements, so the bridge girders for this project are equipped with high performance concrete with a compressive strength of 10,000 psi (69 MPa) at 28 days and thirty 0.7-in. (17.8-mm) diameter strands per girder, making them incredibly strong and able to support the bridge superstructure.
Finally, the challenge of using 0.7-in. (17.8-mm) strands is easily solved with precast concrete, as the strands can be fed through the bulkheads, held down with larger chucks, and secured in the girders prior to delivery to the construction site. Precast concrete is a great solution for the Pacific Street Bridge over I-680, offering increased safety, reduced construction time, and improved durability.