Construction Time

Подпись: Copyright © Marcel Dekker, Inc. All rights reserved.The speed of construction has assumed an increasing importance in reducing the overall cost of a building project. The rapid and efficient method of stripping, raising, and positioning of formwork through the self-raising forms has increased the rate of construc­tion of the service core and lift shafts. Traditional forming tech­niques typically take four to five days to complete a 30,000 ft2 (2800 m2) floor, but with self-raising forms only two to three days are needed to complete the same floor. The stripping and raising of the forms from one floor to the next typically takes 20 to 30 min­utes. This efficient method of forming results in direct cost reduc­tion is due to reductions in construction time.

Подпись:The labor force needed for the stripping, raising, and positioning of the forms is greatly reduced from the conventional formwork systems. Typically 10 to 12 workers are needed as compared to 20 or more for conventional or jump forming. The work crews are split into groups of two to three workers, which are then assigned a particular task. The workers usually work in a clockwise manner around the building with one crew working ahead of the others. The self-raising forms are prefabricated and remain connected un­til the top of the building is reached. This reduces the need to assemble and disassemble the forms after each lift.

With the use of built in hydraulic rams to raise the formwork system, the requirements for crane time and crane attendants is greatly reduced. Craning operations are only needed to initially place the formwork system and to disassemble the system once the forming is complete. This allows the crane to be used else­where on the job site, thus possibly increasing productivity else­where since the crane is rarely needed with the self-raising forms.