William R. Fleischman, Ohio Turnpike Commission
In conjunction with the Third Lane Widening program, the Ohio Turnpike Commission is reconstructing the twin, high-level bridges over the Cuyahoga River Valley in Summit County, near Akron, Ohio. The new 18-span structures are each 2,660 ft (811 m) long and approximately 175 ft (53 m) above the Cuyahoga River Valley. The Cuyahoga River Bridges are the longest and highest structures on the Ohio Turnpike’s 241-mile (388-km) long system. The project has a total construction cost of $52 million.
The new eastbound structure, constructed on a new alignment, was completed and opened to traffic in October 2001. The old eastbound structure was subsequently demolished. The new westbound structure is currently under construction. All of the substructure units are in place and girder erection is almost complete. When the new westbound structure is complete, the old westbound structure will be demolished.
An Ohio Department of Transportation (ODOT) Class C mix with a required compressive strength of 4000 psi (28 MPa) was selected for use on the substructure units.
Girders
The 18-span superstructure of each bridge consists of three units. Unit No. 1, with a length of 357 ft (109 m), consists of three spans of 72-in. (1.83-m) deep precast, prestressed concrete girders. Six girders spaced at 11-ft 0-in. (3.35-m) centers are used in each span. Unit No. 2 consists of two spans of 150 ft (45.7 m) and three spans of 200 ft (61.0 m) for a total length of 900 ft (274 m). Seven precast, prestressed, post-tensioned spliced girders 102 in. (2.59 m) deep spaced at 9-ft 2-in. (2.79-m) centers are used in each span. Unit No. 3, with a length of 1399 ft (426 m), consists of ten spans of 84-in. (2.13-m) deep precast, prestressed girders. Six girders spaced at 11-ft 0-in. (3.35-m) centers are used in each span. Span lengths in Unit Nos. 1 and 3 range from 115 to 142 ft (35.1 to 43.3 m).
The girders have a modified AASHTO girder cross section obtained by increasing the depth and width. Individual casting lengths vary from 99 to 142 ft (30.2 to 43.3 m). The typical girder weighs approximately 170,000 pounds (77.1 Mg). The girders were transported to the site using dual 6-axle dollies.
The Unit 2 girders have two 4-in. (100-mm) diameter and eight 2-in. (50-mm) diameter ducts per girder. The 4-in. (100-mm) diameter ducts accommodate the longitudinal post-tensioning tendons and have a total length of 900 ft (274 m). Each longitudinal post-tensioning tendon consists of eighteen 0.6-in. (15.2-mm) diameter 7-wire strands. The 2-in. (50-mm) diameter ducts, with a length of 15 ft (4.57 m), are located in the beam end blocks to accommodate the 1.25-in. (32-mm) diameter post-tensioning bars at the field splices.
The specified concrete compressive strengths for the girders were 6500 psi (45 MPa) at transfer and 7500 psi (52 MPa) at 28 days. The 102-in. (2.59-m) deep girders were cast in sets of three in a casting bed 350 ft (107 m) long. Each prestressing strand had approximately 36 in. (914 mm) of elongation during tensioning. After the concrete was placed, the girders were steam cured for approximately 18 hours. In this short amount of time, the typical compressive strength reached 7500 psi (51.7 MPa).
The 84- and 72-in. (2.13- and 1.83-m) deep girders were cast in sets of two on a 350-ft (107-m) long automated hydraulic casting bed. After steam curing was completed, the formwork was removed in minutes using a hydraulic system mounted to the formwork shell. This automated formwork greatly enhanced production efficiency.
Deck
The bridge decks, barriers, and girder end diaphragms required 13,800 cu yd (10,600 cu m) of high performance concrete (HPC) with a specified 28-day compressive strength of 4500 psi (31.0 MPa). This HPC utilized ground granulated blast-furnace slag (GGBFS) and silica fume. The actual average strength was 7000 psi (48.2 MPa). Deck thickness is 9 in. (230 mm) in Units 1 and 3 and 8-1/2 in. (215 mm) in Unit 2. Stay-in-place metal forms were used in all deck placements.
The deck slab was designed utilizing ODOT bridge design standards. Several specialized materials were used to enhance the durability of the deck. The HPC provides a denser, less permeable concrete that reduces chloride penetration. The application of a silane concrete sealer further enhanced this resistance. All reinforcing steel in the deck is epoxy coated to provide additional protection against corrosion.
Deck placement sizes varied from 160 to 460 cu yd (122 to 352 cu m). End diaphragms were placed monolithically with the deck. Midspan sections of the deck were placed first and followed by the other sections. Deck placements for the new eastbound bridge deck occurred over a 17-day period. The deck concrete was cured for 7 days with wet burlap.
This project is scheduled for completion late in 2003 and is a key link in the program to add an additional lane in each direction on a 160-mile (258-km) long segment of the Ohio Turnpike.
Further Information
For further information, contact the author at [email protected]. or 440-234-2081