ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/306186
The town of Enfield, Conn., completed c o n s t r u c t i o n o f t h e i r f i r s t t o t a l l y precast concrete bridge structure with the South Maple Street Bridge over the Scantic River. The existing bridge was built in 1925 and had been rehabilitated and strengthened several times but had met its life expectancy. It was a 66-ft-long single span. The replacement bridge on the same 10-degree skew alignment is an 82-ft-long, 45-ft-wide, single-span structure that carries two, 11-ft-wide t r a ff i c l a n e s , t w o 6 - f t si d ew a l k s , and two 4-ft-wide bicycle lanes. The detour for the project was relatively cumbersome and the town wanted the bridge closed for the shortest possible duration. The town agreed with its engineering consultant to replace the bridge using an accelerated bridge construction (ABC) concept. The consultant developed a conceptual ABC plan and served as the owner's representative during construction. On the basis of the conceptual plans, the contractor was selected to finish the design, develop shop drawings for the ABC solution, and plans for the utilities and approach work. The contractor selected the precaster, who in tur n selected the precast design engineer to finalize the design and prepare shop drawings for the production of the precast concrete. The ABC Concept The new bridge was assembled from 7 1 p re c a s t c o n c re t e c o m p o n e n t s comprising 42 unique elements each of which required special detailing. The precast concrete elements included: • Foundation—19 footing blocks, 3 ft 0 in. thick and typically 13 ft long by 8 to 10 ft wide. Fourteen required skewed edges. The blocks incorporated threaded jacks to level them to grade after setting. Each had three, but up to six, 2-in.- diameter holes through which to inject grout after leveling. • Abutment Walls—10 abutment panels 3 ft 1 in. thick. Panels were either 12 ft 9 in. or 14 ft 8 in. tall and varied from 5 ft 10 in. to 10 ft 8 in. wide. • Wingwalls—13 pieces that varied in thickness from 3 ft 10 in. at the bottom to 1 ft 6 in. at the top. A typical panel was 22 ft tall by 10 ft wide. These panels were cast with an ashlar stone pattern on their exposed face using a formliner. Tops of the panels contained bolts and extended reinforcement for attachment of rail posts and cast- in-place concrete end blocks. • Bridge Seat Beams—two pieces 47 ft 6 in. long and 3 ft 7 in. wide. One was set on the top of each profile SOu TH MAPLE STREET BRIDGE / ENFIELD, CONNECTICUT PR ojECT ENGINEER: Tectonic Engineering & Surveying Consultants P.C., Rocky Hill, Conn. PRECAST DESIGN ENGINEER: Hoyle, Tanner & Associates Inc., Burlington, vt. PRIME CoNTRACToR: Arborio Corporation, Cromwell, Conn. PRECASTER: William E. Dailey LLC (Dailey Precast), Shaftsbury, vt., a PCI-certified producer by Charles H. Swanson, Hoyle, Tanner & Associates Inc. South Maple Street Bridge over the Scantic river Emulation design provides robust structure in just 17 days The existing bridge had met its life expectancy. Photo: Ralph Sweet. The South Maple Street Bridge over the Scantic River at completion. Photo: Arborio Corporation. 32 | ASPIRE , Summer 2011 Book_Sum11.indb 32 7/1/11 9:59 AM