THE JUMP FORM SYSTEM

Fully mechanised public housing construction in Hong Kong in the late 1990's involves the following features:

1. the use of a climbing formwork system (sometimes referred to as self-climbing or self-lifting) to construct the central core walls,
2. precast facades and steel panel formwork (or alternatively climbing formwork) to construct the residential wings,
3. aluminium system soffit formwork to construct the floor slabs.

The central core is typically constructed ahead of the residential wings by using a climbing formwork system. The wings then "spiral" around the central core.
The jump form illustrated here is a climbing formwork system developed by Leighton Contractors (Asia) Ltd.

The use of climbing formwork (jump form) to construct the cores. Precast facades and steel panel formwork are used in the construction of residential wings.

The use of climbing formwork (jump form) to construct the cores. Precast facades and jump form are also used in the construction of the residential wings.

The animation illustrates the process. A frame is constructed from structural steel members over the central core. Steel formwork panels are hung from this frame, some supported on rollers. After the concrete walls are poured, the formwork is released and rolled back from the concrete face. Jacks then lift or climb the whole frame up one level. All the formwork panels are attached to the frame. This process takes approximately one and a half hours.
Once the climbing formwork is in position, the formwork panels are closed and the next concrete wall is poured. The cycle continues, which is normally four days. Faster times have been achieved. However, the limiting factor to faster times is usually the construction of the floor slabs, which are done as a separate process.

ANIMATION