GB2053308A

GB2053308A - Beam; floor or roof construction

Info

Publication number: GB2053308A
Application number: GB7923606A
Authority: GB
Original assignee: Conder International Ltd
Current assignee: Conder International Ltd
Priority date: 1979-07-06
Filing date: 1979-07-06
Publication date: 1981-02-04
Also published as: GB2053308B

Abstract

A beam 1 has a spine plate 2 fixed along the length of its top, intermediate its sides. The spine plate 2 has holes 3 passing therethrough. A floor or roof is formed by placing reinforcement 5 in position, the reinforcement passing through the holes in the spine plate, and pouring a forming material, with suitable shuttering 4. The cooperation of the spine plate 2, reinforcement 5 and material 6 forms shear connections between the material 6 and the beams 1. <IMAGE>

Description

SPECIFICATION Floor or roof construction BACKGROUND OF THE INVENTION The present invention relates to a method of constructing a floor or roof, to a floor or roof construction constructed by the method, and to a beam for the floor or roof construction.

It is well known to make floors or roofs by erecting support bearns and pouring a floor or roof forming material, with suitable shuttering, to form the floor or roof, supported by the beams.

It is now considered that the beams and the forming material (which would normally be concrete) should be tied together so that there is horizontal shear transfer and so that vertical separation is impossible. This causes the beams and the forming material to work compositely, and can improve structural efficiency and enable the structural depth to be reduced. In order to achieve such composite action, discrete projections are fixed to the upper surface of the beam, normally by welding them onto the beam, and these projections are so shaped that when the forming material sets, the projections provide a suitable interlock.

THE INVENTION The invention providers the method of Claim 1, the floor or roof construction of Claim 7 and the beam of Claim 9. Claims 2 to 5 and 10 claim preferred features of the invention.

Using the invention the reinforcement is connected to the upstanding part and is thereby connected to the beam, and the reinforcement is anchored in the floor or roof material. This provides a shear connection between the floor or -roof material and the beam, preventing relative movement in the vertical or horizontal directions.

Substantial movement between the pieces of reinforcement and the upstanding part could be prevented by grouting, i.e. filling the spaces between the pieces and the sides of the holes with the floor or roof material, but the preferred method is as in Claim 3.

The invention can have the following advantages: (a) The upstanding part forms, together with the beam itself, a composite beam; this enables the cross-section of the beam to be reduced or the depth of concrete to be reduced; alternatively, the greater stiffness of the composite beam during erection can reduce the requirernent for propping.

(b) Standard reinforcing rods can be used as a reinforcement, and these can easily be adapted to suit variable site conditions, and can for instance be bent.

(c) The number of shear connections per unit length can be varied simply by altering the number of holes, for example when punching the holes; for instance, more holes can be provided at the ends of the beams than in the centres of the beams.

(d) As well as providing shear connectors, the reinforcement provides a tie between the moulding material, on either side of the beam.

(e) The composite beam does not have projecting parts which can tangle with other composite beams, leading to easier transport and handling.

If the method is in accordance with Claim 2, the upstanding part of the composite beam can be relatively thin, leaving support surfaces on either side which are sufficiently large to support the permanent shutters without notching or cutting the shutters.

In theory, the upstanding part could be formed integrally with the remainder of the beam, but it is preferably initially separate from the beam. If it is welded in position, the assembly of the composite beam can be fully automated, and the weld size and the spacings between welds can be adjusted as appropriate.

If desired, when the holes are formed in the upstanding part, tabs can be bent out of the plane of the upstanding part to increase the shear connection; these tabs can run up the sides of the holes or can be bent out from the top or the bottom of the holes, i.e. being vertical or horizontal.

DESCRIPTION OF PREFERRED EMBODIMENT The invention will be further described, by way of example, with reference to the accompanying drawing, which is an isometric projection, mainly cut-away, of a floor or roof construction in accordance with the invention.

The floor or roof construction has a number of spaced, parallel beams, one of which is shown.

The beams are hot rolled in steel, and a spine plate 2 is welded as an upstanding part along the whole length of the centre of the top flange of the beam 1. The spine plate 2 has spaced holes 3 which pass right through from one side to the other. The specific shape of the hole 3 is described below.

The ends of permanent shutters in the form of concrete slabs 4 are rested on the support surfaces on either side of the spine plate 2, each slab spanning two adjacent beams 1. It will be appreciated that a different construction could be used at the edge of the floor or roof.

Conventional reinforcing bars 5 are passed through the holes 3, above the level of the slabs 4. The bars 5 are then anchored in the spine plate 2 in any suitable manner. One way is to form circular holes or long-shaped holes 3 in the spine plate 2, and drive home alongside the bar 5 a tapered wedge of a material which is softer than the spine plate 2 and the bar 5. A preferred way however is to have the holes 3 of wedge shape with a larger end which is wider than the bar 5 and a smaller end which is narrower than the bar 5, and then driving the bar 5 home towards the smaller end to anchor the bar 5 to the spine plate 2. To give an example, if the diameter of the bar 5 is d, the holes 3 can have an overall length of 3d, the larger end a diameter of 1 .5d and the smaller end a diameter of 0.85-0.9d.

In any case, by anchoring the bar 5 to the spine plate 2, it is not essential that the moulding material 6 should pass into the hole to lock the bar 5 into the hole.

Claims

1. A method of constructing a floor or roof, comprising: erecting support beams, each of which has an upstanding part running along substantially the whole length of its top, intermediate the sides of the beam, so as to leave a support surface on each side of the upstanding part, the upstanding part having holes passing therethrough from one side to the other; placing reinforcement in position, the reinforcement including pieces passing through the holes in the upstanding parts; and pouring a floor or roof forming material, with suitable shuttering, to form the floor or roof, supported by the beams, substantial movement being prevented between the upstanding part and the pieces of reinforcement passing therethrough.

2. The method of Claim 1, comprising placing permanent shutters on the support surfaces of the beams, each shutter spanning two adjacent beams with its respective end portions resting on the support surfaces, the holes being above the level of the tops of the permanent shutters.

3. The method of Claim 1 or 2, wherein the reinforcement is anchored to the upstanding part before pouring the forming material.

4. The method of Claim 3, wherein each of the holes is generally of wedge shape having a larger part which is wider than the respective piece of reinforcement and a smaller part which is narrower than the respective piece of reinforcement, the piece of reinforcement being passed through the hole and then forced towards the smaller part to anchor the piece to the upstanding part.

5. The method of any one of the preceding Claims, wherein each respective beam is a hotrolled steel beam, the upstanding part being initially separate from the beam and being secured to the top surface of the beam.

6. A method of constructing a floor or roof, substantially as herein described with reference to, and as shown in, the accompanying drawing.

7. A floor or roof construction, constructed by the method of any one of Claims 1 to 6.

8. A floor or roof construction, substantially as herein described with reference to, and as shown in, the accompanying drawing.

9. A beam for use in the method of Claim 1, for supporting a floor or roof, the beam having an upstanding part running along substantially the whole length of its top, intermediate the sides of the beam, so as to leave a support surface on each side of the upstanding part, the upstanding part having holes passing therethrough from one side to the other.

10. The beam of Claim 9, and being as defined in Claim 4 or 5.

11. A beam, substantially as herein described with reference to, and as shown in, the accompanying drawing.