GB2437142A

GB2437142A - Prefabricated concrete section for use in constructing a lift shaft

Info

Publication number: GB2437142A
Application number: GB0607461A
Authority: GB
Inventors: Wayne Toghill; Raymond Gerson
Original assignee: WAYCON PRECAST Ltd
Current assignee: WAYCON PRECAST Ltd
Priority date: 2006-04-13
Filing date: 2006-04-13
Publication date: 2007-10-17
Anticipated expiration: 2026-04-13
Also published as: GB2437142B; GB0607461D0

Abstract

Each section comprises four side walls 1 to 4 defining four corners 15 to 18 extending between top and bottom faces, and a reinforcing post 20 incorporated into each corner during casting of the section. The post may include a vertical element which is encased in concrete with top and bottom plates which define the top and bottom corner faces of the section. The top plate has a screw threaded socket for receiving a lifting loop 40 or a locating pin 36, 37, and the bottom plate has a hole for receiving the pins of another such section. One of the locating pins 37 may be significantly higher than the others to assist location during assembly of the lift shaft. Later embodiments relate to a lift shaft constructed from said concrete sections, a method of forming said concrete sections and a method of constructing a lift shaft using said sections.

Description

PREFABRICATED CONCRETE SECTIONS FOR USE IN

CONSTRUCTING A LIFT SHAFT

TECHNICAL FIELD OF THE INVENTION

This invention relates to the manufacture of prefabricated concrete sections for use in constructing a lift shaft.

BACKGROUND

GB 2 363 110 A discloses a method of constructing a lift shaft from prefabricated reinforced concrete sections which are stacked one upon another. The sections are precast in a mould having inner and outer shuttering secured to a vibrating table, following which the sections are transported to site for assembly of the lift shaft.

It has been found that it is not always possible to achieve a desirable level of consistency in the dimensions of the prefabricated sections using the method described. For example, forces produced during stripping of the mould can cause damage to the top and bottom faces of the sections, particularly close to the corners, and whilst such damage is not structurally detrimental this is not always appreciated by the customer Time consuming repairs often have to be carried out to keep the customer happy In addition, to ensure that the top face of each finished section is flat and true it is usually necessary to slightly overfill the mould to allow for settlement during vibration and then cut or grind each side of the cast section prior to use. This too is a time consuming and skilled process, producing large amounts of dust if performed dry, or a slurry of concrete particles in water if performed wet. There is also a significant risk that the sides will be cut or ground incorrectly The present invention seeks to provide a new and inventive way of manufacturing the concrete sections which enables a consistently high level of dimensional accuracy to be achieved

SUMMARY OF THE INVENTION

The present invention provides a prefabricated concrete section for use in constructing a lift shaft from a number of such sections stacked one upon another, in which the prefabricated concrete section has four side walls defining four corners extending between top and bottom faces, and a reinforcing post is incorporated into each corner during casting of the section.

The reinforcing posts preferably extend between top and bottom faces of the said section Each reinforcing post preferably includes an elongate element which is substantially encased within the concrete section.

Preferably each reinforcing post includes a top plate which is substantially flush with said top face. The periphery of the top plate preferably extends along respective portions of two adjacent outer faces of the section, and preferably along respective portions of two adjacent inner faces of the section.

Preferably each reinforcing post includes a bottom plate which is substantially flush with said bottom face. The periphery of the bottom plate preferably extends along respective portions of two adjacent outer faces of the section, and preferably along respective portions of two adjacent inner faces of the section Each top plate is preferably provided with a pin to project upwardly from the respective top plate, and each bottom plate preferably has a hole for receiving a corresponding pin of another section on which the section is stacked in use Preferably one of the pins is longer than the pins of the other reinforcing posts of the same prefabricated section.

One or more lifting loops may be provided for releasable engagement with the top plates.

The pins may be received in sockets which are fixed with the top plate and cast into the concrete section. The pins are preferably removably engaged with the sockets by means of screw threads so that a lifting loop may be engaged with a socket in place of a pin.

The invention includes a lift shaft constructed from a number of such prefabricated concrete sections stacked one upon another.

The invention also provides a method of forming a prefabricated concrete section for use in constructing a lift shaft from a number of such sections stacked one upon another, in which the prefabricated concrete section is formed with four side walls defining four corners extending between top and bottom faces, and a reinforcing post is incorporated into each corner during casting of the section.

The invention further provides a lift shaft from a number of prefabricated concrete sections which are stacked one upon another, in which each prefabricated concrete section has four side walls defining four corners extending between top and bottom faces, and a reinforcing post is incorporated into each corner during casting of the section.

According to a second aspect, the invention provides a prefabricated concrete section for use in constructing a lift shaft from a number of such sections stacked one upon another, in which the prefabricated concrete section has a plurality of upwardly projecting pins for reception in corresponding holes in another section which is stacked thereon in use, and one of the pins projects significantly higher than the other pins

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings Ficiure 1 is a general view of part of a lift shaft being constructed of prefabricated concrete sections in accordance with the invention; Ficiure 2 is a side view of a reinforcing corner post which is incorporated in the prefabricated sections; and Fiçure 3 is a top view of the corner post

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, the illustrated lift shaft may be formed of prefabricated door sections 10 and spacer sections 12 The shaft sections 10 and 12 are rectangular in plan view with four side walls 1 2, 3 and 4 and four corners 15, 16, 17 and 18. In the case of the door sections 10, one of the side walls 1 is formed with a vertical door opening 6. The spacer sections 12 are similar to the door sections 10 except that they are shorter and contain no door apertures.

Each corner of the sections 10 and 12 contains a reinforcing post 20, one of which is shown in detail in Fig.s 2 and 3. The posts 20 are cast into the sections during prefabrication, as described below. Each post incorporates a vertical elongate element 21 of substantially the same height as the respective section, and which may comprise a straight length of rod, tube or bar, e.g. of L or H section, of substantially the same height as the respective shaft section 10, 12. A pair of top and bottom plates 22 and 23 are welded or otherwise secured to opposite ends of the element 21 to project perpendicularly therefrom. To ensure dimensional accuracy, the four posts for each section of the lift shaft are all manufactured in the same jig As shown in Fig. 3, the peripheral profile of each plate includes a pair of mutually perpendicular straight portions 25 and 26 which extend along the outer faces of the two adjoining walls (e g.

waIls 1 and 2 as indicated in outline), with a second pair of mutually perpendicular straight portions 27 and 28 which extend along the inner faces of the two walls. In the moulded shaft sections, the two plates are substantially flush with the top and bottom faces of the respective section.

The top and bottom plates 22 and 23 contain a pair of accurately aligned apertures 30. The top plate 22 has an internally screw-threaded socket 31 secured in registration with the aperture 30 to lie within the cast concrete section For additional strength, an anchor 32, such as a length of externally profiled reinforcing bar, is joined between the bottom of the socket 31 and the vertical element 21 (See Fig. 2.) The anchors 32 ensure that the sockets remain accurately located during pouring of the concrete and are firmly anchored within the cast section The bottom plate 23 has a plain tubular sleeve 34 secured in registration with the aperture 30 to be embedded in the cast concrete section The corner posts are also provided with locating pins 36 and 37, each having an externally screw threaded end portion 38 for reception in the socket 31. Each shaft section has three relatively short locating pins 36 and one significantly longer pin 37 In addition, wire lifting loops 40 are provided (four for each shaft section) each secured to an externally screw threaded portion 42 for reception in the socket 31.

In the construction of a new building incorporating a lift shaft, a pit section of the lift shaft may extend up to 1.6 metres below the lowest floor elevation of the building. This pit section is prefabricated off site and then lowered onto prepared foundations at the appropriate elevation and bedded on non-shrink grout. A thin layer of epoxy grout is the laid onto the top faces of the walls of the pit section and a door section 10 having four lifting loops 40 inserted into the sockets 31 is lowered onto the upper faces of the pit section by crane using the loops 41 The loops are then unscrewed from the sockets 31 and replaced by three short pins 36 and one long pin 37, as shown in Fig. 1. A thin layer of grout is laid onto the top faces of the walls 1-4 and a spacer section 12 is lowered onto the door section, again using lifting loops 40 inserted into the sockets 31. The section being lowered is first located so that the longer locating pin 37 enters the corresponding sleeve 34 of the section being lowered The section is then rotated about the longer pin until the three remaining sleeves 34 are aligned with the three shorter pins 36 and the section is then lowered into its final position As each section is lowered into position the lifting loops are removed and replaced with the locating pins.

The combined height of one door section and one spacer section is usually equal to the height of a single floor Hence, for a three storey building, allowing for the pit section and a housing at the top of the shaft for the lift winding equipment, a total of eight sections will be required to form the lift shaft, namely the pit section, three door sections, three spacer sections, and the top mechanical housing The formwork used in constructing the shaft sections has spaced inner and outer shuttering moulds mounted on a vibrating table, as described in the earlier specification referred to above. During manufacture a reinforcing steel skeleton is constructed around the inner mould. The four corner posts are clamped into position and the skeleton is attached to the posts as the reinforcing cage is constructed. The bottom plate is clamped down to ensure contact with the floor of the mould during concrete pouring and vibration. When construction of the cage is complete the outer shuttering is assembled around the cage and the concrete is poured into the intervening space. The two plates 22 and 23 locate the corner post accurately in the mould prior to casting, and also protect the corners of the section during stripping of the mould.

The use of the corner posts significantly increases the overall dimensional accuracy of the sections and substantially reduces the time required for manufacture of the sections and construction of the lift shaft on site. The four corner posts accurately define the positions of the eight top and bottom corners of the shaft section. Using the top plates for reference, each side of the mould can be filled with concrete to the required level during vibration and pouring, and overfill can be kept to a minimum. In the event that overfill should occur, the top plates can be used as accurate reference points for subsequent cutting and grinding. The plates also minimise degradation of the corners during mould stripping, and ensure the overall dimensional accuracy of the shaft sections. The pins and sleeves are accurately positioned to ensure precise location of one shaft section on another during erection, and the use of one longer pin as described, together with the accurate positioning of the lifting loops, also significantly speeds up and simplifies the construction process.

It will be appreciated that the features disclosed herein may be present in any feasible combination. Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.

* * * * * * * *

Claims

CLAIMS

1. A prefabricated concrete section for use in constructing a lift shaft from a number of such sections stacked one upon another, in which the prefabricated concrete section has four side walls defining four corners extending between top and bottom faces, and a reinforcing post is incorporated into each corner during casting of the section.

2. A prefabricated concrete section according to Claim 1, in which each reinforcing post extends between said top and bottom faces.

3. A prefabricated concrete section according to Claim I or 2, in which each reinforcing post includes an elongate element which is encased within the concrete section.

4. A prefabricated concrete section according to Claim 3, in which each reinforcing post includes a top plate which is substantially flush with said top face.

5. A prefabricated concrete section according to Claim 4, in which the periphery of the top plate is substantially flush with the outer faces of the two adjacent side walls.

6 A prefabricated concrete section according to Claim 4 or 5, in which the periphery of the top plate is substantially flush with the.inner faces of the two adjacent side walls 7. A prefabricated concrete section according to Claim 4, 5 or 6, in which each top plate is provided with a pin to project upwardly from the respective top plate 8 A prefabricated concrete section according to Claim 7, in which one of the pins is longer than the pins of the other reinforcing posts of the same prefabricated section 9 A prefabricated concrete section according to Claim 7 or 8, in which the pins are received in sockets which are fixed with the top plate and cast into the concrete section 10. A prefabricated concrete section according to Claim 9, in which the pins are removably engaged with the sockets by means of screw threads.

11. A prefabricated concrete section according to Claim 10, in which each top plate is provided with a lifting loop which may be releasably engaged with the socket by means of screw threads 12. A prefabricated concrete section according to any preceding claim, in which each reinforcing post includes a bottom plate which is substantially flush with said bottom face 13 A prefabricated concrete section according to Claim 12, in which the periphery of the bottom plate is substantially flush with the outer faces of the two adjacent side walls.

14 A prefabricated concrete section according to Claim 12 or 13, in which the periphery of the bottom plate is substantially flush with the inner faces of the two adjacent side walls A prefabricated concrete section according to Claims 7 and -11 - 12, in which each bottom plate has a hole for receiving a corresponding pin of another section on which the section is stacked in use.

16. A lift shaft constructed from a number of prefabricated concrete sections according to any of Claims 1 to 15 stacked one upon another 17 A method of forming a prefabricated concrete section for use in constructing a lift shaft from a number of such sections stacked one upon another, in which the prefabricated concrete section is formed with four side walls defining four corners extending between top and bottom faces, and a reinforcing post is incorporated into each corner during casting of the section 18. A method of constructing a lift shaft from a number of prefabricated concrete sections which are stacked one upon another, in which each prefabricated concrete section has four side walls defining four corners extending between top and bottom faces, and a reinforcing post is incorporated into each corner during casting of the section.

19 A prefabricated concrete section for use in constructing a lift shaft from a number of such sections stacked one upon another, which is substantially as described with reference to the drawings * * * * * * * *