Slipforming of Reinforced Concrete Shield Building: Fid-Bau Portal

Slipforming of Reinforced Concrete Shield Building

Hsieh, M. C. / King, Jerome R.

The unique design and construction features of slipforming the heavily reinforced concrete cylindrical shield walls at the Satsop nuclear plant site are presented. It proved that, with proper planning, design, and coordination, the slipform construction technique can be successfully applied to large and heavily reinforced concrete structures. The shield walls were designed in compliance with seismic requirements which resulted in the need for reinforcing steel averaging 550 pounds per cubic yard (326 kg/m³). A 25 ft (7.6 m) high, three-deck moving platform was designed to permit easy installation of the reinforcing steel, embedments, and blockouts, and to facilitate concrete placement and finishing. Two circular box trusses, one on each side of the shield wall, were used in combination with a spider truss to meet both the tolerance and strength requirements for the slipform assembly. Use of preassembled, lifted-in-place sleeve tower racks that combined diagonal and vertical bars for the openings with two vertically aligned pipe sleeves greatly eased the installation. Specific recommendations for future slipforming are also presented.