Concrete slab lifting system

Abstract

The invention provides a system and method of lifting and conveying a concrete slab and / or associated works. The slab has an area includes a plurality of apertures therethrough. A jack at least comprising a shaft having a portion passes through the aperture and contacts a lower support means. The system includes a means for connecting the slab to the shaft. The connection means incorporates at least one supporting member connecting the slab to the shaft. Each supporting member passes through another said aperture and engages the slab. Also included is a means for effecting longitudinal travel of said supporting means along said shaft, resulting in the raising or lowering of said slab. Position sensors are associated with each jack and the system includes a means for communicating and controlling between each jack and one or more main controllers. There is also provided a jack for lifting a concrete slab which includes a shaft and ball screw, a drive assembly, a hanger assembly, a support device. The drive assembly drives the ball screw to raise the shaft with respect to the hanger assembly such that the jack has climbed the support device supports the shaft to prevent toppling and provide stability.

Description

TECHNICAL FIELD OF THE INVENTION [0001] This invention relates to the lifting of pre-cast concrete slabs and has particular application to a method and apparatus for constructing a multi-storey building. BACKGROUND OF THE INVENTION [0002] A jacking system as developed by the inventor of the present invention, in U.S. Pat. No. 5,644,893, covered a system for constructing multi-storey buildings. The system comprised extendible props (or jacks) being retractable and having cable suspension means. However in practice this system was found to have many problems that stimulated the development of the current system of this application. [0003] The suspension means of the prior art was found to be impractical whereby the connection to the slab below was not workable due to the high jacking point loads involved creating seriously weakened slab portions. Also during use of the system when the jack was disconnected from each floor, there was no means of support for the jack to prevent toppling...

AI Technical Summary

Benefits of technology

[0007] Preferably the jack includes trailing restraint means being adapted to provide restraint and or stability for the jack once it has climbed or the jack has been disconnected from the slab.

[0069] In a further aspect, the invention provides a method of lifting a concrete slab using at least one jack, each jack including: a shaft and ball screw, a drive assembly, a hanger assembly, a support device wherein the drive assembly drives the ball screw to raise the hanger assembly with respect to the shaft such that in use when the jack has climbed to raise a slab, the support device supports the shaft to prevent toppling and provide stability wherein the steps include:

Problems solved by technology

However in practice this system was found to have many problems that stimulated the development of the current system of this application.

The suspension means of the prior art was found to be impractical whereby the connection to the slab below was not workable due to the high jacking point loads involved creating seriously weakened slab portions.

Also during use of the system when the jack was disconnected from each floor, there was no means of support for the jack to prevent toppling.

There was also no means to redistribute the load from the jack to reduce effective slab loading and push off loading to the floor below.

The jack relied on an extendable mid portion which was inefficient in its operation, expensive to manufacture and difficult to stabilise during use.

Importantly there was no means for coordinated accurate slab / jack position control.

Also existing scaffolding systems are time consuming to erect and dismantle and restrict site movement creating a hazard.

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