The Dallas area Rapid Transit Authority's (DART) 45-mile light rail system is one of the best in the nation. With funds from the American Recovery and Reinvestment Act, DART has launched a major expansion.
One section of the rail system will travel over a 550-foot prestressed concrete bridge spanning the Trinity River levy. The 260-foot center span consists of 97-foot-long x 10-foot, 10-inch-tall haunch girders at the piers and a middle drop beam section 160-foot-long x 6-foot, 10-inches-tall. The end and center spans of the bridge are typical TX82 girders.
The precast/prestressed producer, San Antonio-based Bexar Concrete Works I, chose Hamilton Form Co. in Fort Worth, Texas, to build forms for the project. “On a complex design/build project of this magnitude, the forms play a critical role in the project's success,” says Bexar's Jorge Hinojosa.
To cast the 97-foot-long haunch girders, Hamilton Form built 11-foot, 2-inch-tall haunch sideforms and a 33-inch-wide soffit. The soffit slopes 4 feet in the middle to create the drop in the center of the beam. “We built a sloped soffit instead of sloped sideforms to make it easier for the customer to set up the formwork,” says Taylor Slate, engineering manager. “The formwork is built in sections. Each section of soffit and sideforms is matched and marked on a dead level working jig, and we set up and check the forms before shipping.”
The manufacturer sealed the form against the soffit with a thru tie system 2 inches below the bottom casting surface. Top ties and thru ties were spaced closer together in the maximum height area of the girder for added support. Vi-brotrack was installed to slide vibrators along the form to consolidate the concrete. Two pour openings prevented the concrete from dropping the full height of the form during the pour.
Visit Hamilton Form at booth #424 at the PCI Show and at www.hamiltonform.com.
Following are more suppliers of precast and prestressed concrete forms.
Light-duty bases, risers, and flat top forms are up to 72 in. in diameter and are fabricated with a thinner steel plate and a slightly lighter gage of channel rib reinforcing, for a typical cost savings of 25% compared to traditional forms. All other parts of the form are exactly the same. Besser Co. 800-968-0444. www.besser.com
The Precast Bollard is a polyethylene pipe with a domed top that is designed to be filled with concrete for added strength. The shell, available in standard or custom colors, eliminates the painting and maintenance of steel pipes. The 7 ft.-tall forms are available in 4- and 7.5-in. diameters. Strike Products. 800-262-4129. www.striketool.com
Cast natural looking walls
CreteWood and CreteStone concrete retaining walls feature realistic wood grain and stone textures. Precast panels up to 5 ft. long fit together with an interlocking design. Licensed manufacturers receive a turnkey system of mold boxes, specific concrete mix, a coloring process, and marketing support. CreteWood Products. 314-822-8572. www.cretewoodproducts.com
Lightweight modular forms
Create precast concrete structures in an infinite number of sizes and shapes with lightweight modular forms. The long-lasting, low-maintenance system consists of simple-to-use forms that help precasters make higher quality products. The heavy-duty lightweight forms include pallet and header systems. Wall-Ties and Forms Inc. 800-444-9692. www.wallties.com
High-strength metal casting
Use BMF Metal Forms for industrial, residential, and commercial jobs, including concrete sidewalks, curbs and gutters, runways, median barriers, and bridge parapets. The forms are sheared, punched, assembled, and welded with maximum strength and rigidity for easy setup, stripping, and reuse. RCL Enterprises. 315-532-1530. www.jaquith.com
The Wedge-It box culvert wet casting form uses wedge motion to release the concrete inner core from the mold. The form helps reduce labor costs with adjustable legs, and header and pallet rings, and a no-hinge design. Interchangeable core and jacket panels can be adjusted to 52 sizes, up to 10 x 12 ft. Custom Welding & Fabrication Inc. 603-942-5170. www.customweldinginc.com
For more information, visit www.theconcreteproducer.com/freeinfo