Safety is the imperative for any construction project, and Duke Energy’s 630-MW Edwardsport integrated gasification combined-cycle station in Knox Country, Ind., is no exception. The $2.6 billion project is expected to enter commercial service in 2012.

The contractor for Edwardsport is F.A Wilhelm Construction. Wilhelm has responsibility for the site construction, including forming and pouring major foundations and other structures on the project. Wilhelm is also responsible for ensuring a safe and productive job site for the hundreds of workers focused on constructing the plant. Wilhelm carefully considered alternative formwork suppliers for a complex 125-foot by 40-foot by 9.5-foot-thick slab weighing more than 4.8 million pounds. Wilhelm selected Doka USA because it was able to deliver the formwork on a tight schedule with a fast set and cycle time, and the company had safe and easy-to-use products (Figure 6).

6. Flexible towers. A load-bearing tower, Staxo 100, was chosen because it could deliver high load capacity; was adaptable to different layouts, floor shapes, and loads; and included integrated safety features. Courtesy: Doka USA

Supporting High, Heavy Loads

Doka USA used Staxo 100 high-load-bearing towers to support the massive concrete pour along with Dokamatic tables to form the 5,600–square foot slab. This particular formwork system was chosen because it could deliver high load capacity; was adaptable to different layouts, floor shapes, and loads; and included integrated safety features. The Staxo 100 load-bearing tower is made of sturdy galvanized steel frames and provides an optimal load capacity of up to 90 kip per tower (Figure 7).

7. Safe and secure concrete pours. Safety was a key concern with the height of this project. Safe access at any location anywhere within the tower using the first built-in ladder and OSHA-approved tie-off points was a selling point for the contractor. Courtesy: Doka USA

Safety was a key concern given the height of this project. Safe access at any location anywhere within the tower was possible by using the first built-in ladder and Occupational Safety and Health Administration (OSHA)–approved tie-off points. These safety features were a strong selling point for the contractor.

Wilhelm’s crew found the shoring system provided quick and easy assembly: Because it used integrated couplers, there were no loose parts. Crews could easily assemble and disassemble the structures. Safety was carefully designed into the erection sequence, as the crew was able to use the integrated ladder and tie-off points that are directly built into the frames. On this project, all three heights of Staxo 100 were used; 3-, 4-, and 6-foot heights.

“We found the system went up easily and quickly. It poured as solid as anything we’ve ever done. Using this system helped us beat our estimate on Duke’s power plant,” said Curtis Arnold, project superintendent for Wilhelm.

Integrating the Table Slab Formwork

The next step was delivery of the tables needed to pour the slab. The Dokamatic tables arrived on site preassembled, saving time and resources, and were set on top of the Staxo shoring system to create a 123.5-foot-long, 40-foot-wide slab area where the concrete would be poured.

Using Dokamatic tables saved on labor and crane time, because the system is optimized for minimal forming times on large deck projects. Fully assembled table form units quickly position into place and eliminate the need for labor-intensive carrying of individual components from one location to the next. The Dokamatic tables allow for quicker cycle time and are ideal for fast formwork handling when casting large floor slabs (Figure 8).

8. Overhead concrete pour. The contractor chose to use the Staxo 100 high-load-bearing tower to support the 4.8 million pounds of concrete and steel, along with Dokamatic tables to form the 5,600-square-foot slab. Courtesy: Doka USA

Using a simple pin connection, Staxo 100 connects directly to the steel stringer of the table unit and allows flying of a large deck formwork section in combination with the Staxo 100 shoring system. The combination of the Staxo 100 shoring system and Dokamatic table slab formwork allowed 90% of the work to be performed on the ground at a safe level and then lifted into place by a crane.

—Contributed by Doka USA.