Handling of units during transportation and on site

Panels require to be lifted from the mould and handled through storage, transportation and finally erection on site. Lifting provision is required in the panels at each stage. One of the main points to consider in the design of precast concrete panels is their weight for handling. Most manufacturers would recommend panels not exceeding 71 for lifting and shuffling' into place on site. This can often place a restriction on the size of the panel, depending upon the density of the concrete used, and the architect must therefore be aware of any weight restriction when determining panel size.

Lifting provision for transportation and erection should if possible be above the centre of gravity, so that r

1.13 Special lifting device for cranked units.

when the panel Is suspended It will hang In a vertical plane. Tilting of the panels during lifting on site can cause difficulties in placing and fixing. Often it is not possible to suspend a cranked unit, such as a spandrel panel, from its outer face because of difficulties of patching over the fixing sockets. Special lifting devices are then used (Fig. 1.13) to support the panel and keep the centre of gravity below the crane hook

Panels are often transported horizontally, and require additional reinforcement and lifting provision for handling when lifted into their vertical position. One method of reducing the stress on the panel during such handling is to use a tilting platform (Fig. 1.1 5). Tight access for crane jibs in relation to the building form should be checked in advance, and

1.14 Special lifting tackle for cranked units.
LIS Tilting platform as used at Liverpool Royal Insurance building.

allowance should be made for clearance for the jib of the crane above panel fixings (Fig. 1.16).

Fixings for handling are usually loops of reinforcement or cast-in sockets for use with patent lifting devices, which take the form of shackles, stranded steel loops, collared eyes or clip-on bolts. Common proprietary lifting devices are shown in Fig. 1.17. Screw-in lifting devices should not be used singly because of the danger of their becoming unscrewed during lifting. Generally speaking, the shackle device has been found to be the most reliable, but it is expensive. Loops are the most common method.These can be left intact, or burnt off when not required. Collared eyes and

Shape of precast concrete cladding panels 21

1.16 Clearance required for crane jib.

Clearance required for crane jib

1.16 Clearance required for crane jib.

shackles are useful for side-hung lifting provision. Clip-on fixings are useful, but the width of hold makes them unsuitable for thin slabs.

Levelling devices

Levelling devices can be used to facilitate panel assembly. They take the form of a cast-in threaded plate and a bolt, which engages in the plate and bears on the floor slab.

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