GB2150968A

GB2150968A - Mounting shuttering on self- supporting reinforcement framework

Info

Publication number: GB2150968A
Application number: GB08430142A
Authority: GB
Inventors: John F Woodward
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-12-07
Filing date: 1984-11-29
Publication date: 1985-07-10
Also published as: GB2150968B; GB8332578D0; GB8430142D0

Abstract

The framework is formed from prefabricated reinforcement members 10 which may be of open-web construction. The shuttering 18 may be spaced from members 10 by spacers 20, and may be attached to members 10 by bolts 19 which engage with nuts 17 attached to members 10. When the shuttering has been removed, nuts 17 may be used to anchor other building components. <IMAGE>

Description

SPECIFICATION Reinforced concrete construction This invention relates to a method of construction in reinforced concrete; and to structures produced by such method.

In conventional reinforced concrete structures, the location and support of shuttering and reinforcement depends upon external means of temporary support which has to be removed after the concrete has set. During construction, the reinforcement carries no significant load.

According to the present invention, there is provided a method of construction in reinforced concrete comprising the steps of prefabricating reinforcement metal work as frame members, assembling the frame members on site to form a structural frame strong enough to support its own weight and also the weight of wet concrete when the latter is poured to encase the frame members.

Preferably, the method includes the step of mounting moulds or shutters on the frame members so that the latter both locate and support the shutters when they bear forces emposed by the weight of wet concrete encasing the frame members.

Further, according to the present invention, there is provided a structure comprising reinforced concrete produced by the method aforesaid.

In comparison with reinforced concrete produced by conventional methods, structures produced in accordance with the present invention achieve labour saving by obviating or mitigating the need for support false work and gives the advantages of accuracy and economy attainable by prefabrication of the frame members in a workshop under good working conditions and using fabricating jigs. Further advantage is that the concrete component of the composite construction is subject to relatively small stress from its own weight which is carried mainly on the metalwork. Virtually the full strength of the concrete can therefore be utilized to withstand imposed loads, resulting in reduced risk of cracking of concrete as compared with conventional reinforced concrete structures.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a perspective view showing parts of two frame members of a structural frame and concrete encasement, in accordance with the present invention; Figure 2 is a cross sectional elevation of part of a beam frame member with shuttering and concrete encasement; Figure 3 is a perspective view of a pre-cast concrete locator, to a larger scale; Figure 4 is a sectional elevation on the line IV-IV in Fig. 1 (to a larger scale); Figure 5 is an elevational view of part of a reinforced concrete structure in the course of construction and shows different means of providing temporary support for a beam in the course of concrete casting; and Figure 6 is a cross sectional elevation similar to Fig. 2, but showing a different configuration of metalwork elements.

In Fig. 1 of the drawings, a column frame member 10 is of rectangular section and open-web construction and consists of four corner members 11 each of rolled steel angle interconnected by metalwork to form an open web consisting of a zig-zag arrangement of bars 1 2 which are welded to the corner members 11 and may be of any suitable cross section. A beam frame member 1 3 is of general configuration similar to the column 10, having corner members 14 interconnected by bars 1 5 forming an open-web construction. The bars designated by reference numeral 1 6 represent supplementary reinforcement elements which may be placed in position within the cage defined by the frame member 1 3 prior to casting of concrete as described hereunder.The beam frame member 1 3 is bolted to the column 10 in a conventional manner.

Both the column and beam corner members, 11 and 14 respectively, are provided with a regular series of fasteners one of which is shown in detail in Fig. 4. Thus, a screwthreaded female element in the form of a nut 1 7 is welded to the inside face of a corner member 11 in alignment with a drilled hole 11A. This provides a means of mounting shutters 1 8 in position around the column or beam frame member using a bolt fastener 1 9.

The shutters 1 8 are spaced from the corner members 11 by means of a spacer 20 in order to provide the proposed concrete encasement with an outer skin portion represented in Fig. 4 by reference numeral 21.

In Fig. 2, the beam frame member 1 3 has shuttering 1 8 mounted thereon by an alternative fixing arrangement utilising a pre-cast concrete locator 22 having the configuration illustrated in Fig. 3. Thus, several locators 22 are positioned along the beam between the lower-most corner members 14 and the shuttering 1 8 is clamped in position by means of a clamping bolt 23 which extends through the locator 22. The top edges of the shutters 1 8 are located by means of spreaders 24.

The column and beam members are prefabricated under workshop conditions and each is made to precise dimensions. The sizes, spacing and shape of each frame member are determined by the requirements to support the loads of shuttering and wet concrete within permissable stresses and deformations.

After setting of the concrete, the composite action will support superimposed loads, and if necessary the strength of the structure may be enhanced by the inclusion of additional reinforcement elements as mentioned above. The entire structural frame produced by site assembly of such frame members is relatively rigid and its components beams and columns and other members are assembled by bolting the frame members together at connections such as are used in conventional structural steelwork. However, it is not always necessary that such connections should have in themselves the strength to withstand normal working loads since the strength of connections will be enhanced by the concrete which is cast around the joint.

The shuttering 1 8 may be attached to the frame members either before or after site assembly. In order to prevent grout seepage into the threads of the fasteners, the open ends of the nuts 1 7 are preferably blanked off. The provision of the fastening arrangements as a regular series on the frame members permits the use of standard shutters having fixing holes at appropriate centres.

The concrete skin portion 21 or cover of concrete externally of the frame members has a thickness dimension determined by the spacers 20. These spacers may either be left in position when the shutters 1 8 are removed, or the spacers may be removed and the remaining cavity filled with mortar. If the cavity is left unfilled, then the screw-threaded female fastening means may be used as an anchor point for the fixing of other building components.

In the case of relatively long slender beams, deflections of frame members under the load of wet concrete may present certain limitations on the method unless specific precautions are taken. Such precautions may take the form either of pre-cambering the frame members to cancel or compensate subsequent deflection; or the provision of temporary support either by means of propping from below, or by the use of diagonal hangers attached to columns at a level above the beam to be cast.The provision of temporary support may be used to impart a reverse deflection to beams thereby pre-stressing them in such a way that the effects of subsequent imposed loads are wholly or partially compensated. In Fig. 5, a temporary support in the form of an adjustable prop is indicated by reference numeral 25; and an alternative temporary support in the form of diagonal hangers is indicated by reference numeral 26. The upper ends of the hangers 26 are attached to as yet unencased points on the columns 10 at the level of unencased beams above the beam to be cast.

It will be appreciated that the shuttering may take different forms and serve also to produce moulded shapes for architectural and/or structural purposes.

Claims

1. A method of construction in reinforced concrete comprising the steps of prefabricating reinforcement metalwork as frame members, assembling the frame members on site to form a structural frame strong enough to support its own weight and also the weight of wet concrete when the latter is poured to encase the frame members.

2. The method claimed in Claim 1 including the step of mounting moulds or shutters on the frame members so that the latter both locate and support the shutters when they bear forces imposed by the weight of wet concrete encasing the frame members.

3. The method claimed in Claim 1 or 2, wherein principal ones of said frame members are of open-web construction.

4. The method claimed in Claim 3, wherein the principal frame members are of generally rectangular section.

5. The method claimed in any one of Claims 2 to 4, wherein the moulds or shutters are associated with the frame members by means of screw-threaded fasteners of which threaded female elements are on the frame members.

6. The method claimed in any one of Claims 2 to 4, wherein the moulds or shutters are mounted on the frame members by means of clamp bolts extending through pre-cast concrete locators placed on the frame members.

7. The method claimed in any one of Claims 2 to 6, wherein the moulds or shutters are spaced from the frame members by spacing means so that concrete encasing the frame members includes an outer skin portion of depth determined by said spacing means.

8. A method of construction in reinforced concrete, substantially as hereinbefore described with reference to and as shown in the accompanying diagrammatic drawings.

9. A structure comprising reinforced concrete produced by the method claimed in any one of Claims 1 to 8.