Transportation Track (Morning)
Precast Substructure Elements for the Tappan Zee Bridge
Nick Burdette, HDR, Pittsburgh, PA
Precast substructure elements were widely used for the 3.1 mile long New NY (Tappan Zee) Bridge to speed construction, improve safety, and provide a durable final product meeting 100 year service life requirements. Massive precast concrete pile cap tubs and prestresed precast concrete pier cap shells are used for nearly 60 approach piers. Design features and challenges are presented for these precast elements made fully composite in the final structure.
South Tenth Street Bridge Rehabilitation
Stan Nalitz, AECOM, Pittsburgh, PA
The South Tenth Street Bridge is a three-span cable suspension bridge. Built in 1933, the structure has a total length of 1,275 feet and links the City of Pittsburgh with its Southside communities.
The presentation will discuss methods and testing used to inspect, analyze and develop a strategy for the rehabilitation. AECOM conducted a thorough in-depth inspection, including an internal cable inspection, to accurately identify the exact location, extent, overall dimensions, and type of each necessary repair. Based on the results of the field inspection, materials testing program, and structural analyses, a comprehensive plan was developed that presents the evaluations, repair recommendations and detailed cost estimates.
One of the key elements of this structural rehabilitation is the inspection, analysis, and rehabilitation of the suspension cables. The cable rehabilitation will include a dehumidification system of both the anchorage and main cables.
Accelerated Bridge Construction Techniques
Robert T. Elliott, CDR Maguire Inc., Pittsburgh, PA and Jonathan Eberle, AECOM, Mechanicsburg, PA
SR 0136-G10 over Little Chartiers Creek & CSX: this presentation will discuss the ABC of a 206’ 2-span continuous integral abutment bridge. Numerous design challenges included constructability, longitudinal and transverse UHPC closure pours, negative moment reinforcing, deflections during precasting, and crane sizing. The presentation will also discuss the unique manner of the bridge erection based on the use of a conventional deck negative moment region rather than the span by span and link-slab approach.
This presentation presents the design and construction undertaken for the replacement of the existing I-95 NB bridge deck using accelerated bridge construction (ABC) technologies. The bridge carries I-95 NB over a high-volume principal arterial roadway and consists of four simple spans (32’-70’-70’-36’) on a nearly tangent alignment having a 35 degree skew. The existing c.i.p. concrete deck is composite and supported on rolled steel beams. The steel beams and the substructure units were reused as part of this bridge rehabilitation project. Preliminary engineering considered a variety of ABC technologies and after careful consideration, full-depth precast concrete deck panels with UHPC longitudinal and transverse deck joint details, expansion joints at piers/abutments and a polyester polymer concrete (PPC) overlay was selected for reasons to be explained. Replacement of the bridge deck required two stages of construction to accommodate the high traffic volume.