GB2070098A

GB2070098A - Panel Structure

Info

Publication number: GB2070098A
Application number: GB8101209A
Authority: GB
Original assignee: BROCKHOUSE Ltd
Current assignee: BROCKHOUSE Ltd
Priority date: 1980-01-15
Filing date: 1981-01-15
Publication date: 1981-09-03
Also published as: GB2070098B

Abstract

A panel structure, more particularly a flooring panel in the form of a grid or grating is made from a mouldable synthetic resin reinforced by preformed elements 14a, 14d, themselves comprising a composite fibre/synthetic resin, preferably of the kind known as "pultrusions". Such pultruded elements 14a, 14d, are assembled into a grid and placed in an appropriate mould in which they are embedded in the mouldable synthetic resin. <IMAGE>

Description

SPECIFICATION Panel Structure This invention relates to a panel structure for use in building and civil engineering, and more particuiarly a flooring panel which may be of a grid-type.

Flooring grids have been made of metal for very many years, but recently a requirement has arisen for comparable grids to be made from corrosion resistant non-metallic, i.e. plastics, materials. However, special reinforcement of such plastics materials is necessary if gratings made therefrom are to have similar load bearing characteristics as their metal counterparts, more particularly with regard to rigidity.

One prior proposal concerns a non-metallic grating made of glass fibre reinforced moulded synthetic resins with an upper layer of the resin containing densely packed hard particles which are in contact with each other to provide a superficial zone resistant to compressive forces.

The glass fibres throughout the moulded resin, and in particular at the lower side of the grating, provide resistance to tensile forces so that longitudinal elements in the grating made in this way afford a rigid beam which will withstand loads imposed on the upper face thereof without excessive deflection.

However, in this prior construction it is necessary to lay the strands of glass fibre within a mould, and this is a time consuming and tedious process. Moreover, if such panels are inadvertently positioned the wrong way up, the load bearing capacity is greatly reduced.

According to the invention a panel structure is formed by embedding in a mouldable synthetic resin a grid of preformed elongated elements comprising a composite fibre/synthetic resin material whereof fibres are orientated lengthwise of the element and are closely packed together.

Such elongated elements are preferably formed by the process known as "pultrusion" in which the fibres are wetted with the appropriate resin and drawn through a die so as to pack them tightly together whilst the resin is cured. The resulting composite fibre/synthetic resin product contains between 65% and 70% by weight of fibre, e.g. glass fibre, and is much stronger than mouldings obtained by simply laying fibres in a mould because the pultruded elements are formed by fibres which are essentially straight and pretensioned in the longitudinal direction. We have found that by embedding such preformed elements in a resin we can obtain the requisite load carrying and flexural properties required for flooring panels or gratings and the like without it being necessary to lay additional reinforcement in that resin, so that the manufacturing process is greatly simplified.Nevertheless, it will be appreciated that additional reinforcement could be incorporated into such resin together with the pultruded elements should this be desirable in any particular case.

The individual elements can be cut to predetermined lengths from pultruded stock and simply laid in the appropriate manner in a mould, for example with the elements arranged in two mutually transverse sets, the elements being interleaved at the points where they cross.

The pultruded material may utilise glass fibre or any other suitable fibre, including vegetable fibres such as jute, and metal filaments or carbon fibres, and any suitable synthetic resin.

Conveniently, all the elements necessary for a single panel may be assembled together into said grid externally of the mould, so that all the elements can simultaneously be deposited in the mould in a single operation, but the elements may be arranged singly into the mould if desired.

Where the panel is to be in the form of a grid or grating, the mould may simply consist of a flat base member with rectangular blocks thereon defining between them intersecting mutually transverse channels in which the grid of elements is received, the channels then being filled with an appropriate synthetic resin. If desired, the height -of at least some of such blocks could be less than the overall depth of the mould, so that by filling the mould completely with synthetic resin the panel would have a deck layer over at least part of its area, the reinforcing elements preferably being provided throughout the full depth of the panel.

Alternatively, in a similar manner the grid could be incorporated in a solid panel simply by utilising a mould without such blocks, or in an analogous manner a grating could be formed with one or more solid areas as required simply by omitting appropriate blocks from the mould.

The invention will now be described by way of example with reference to the accompanying drawings wherein Figure 1 shows a fragmentary isometric view of one corner part of a grating in accordance with the invention; Figure 2 shows a fragmentary side elevation of the grating in the direction of arrow II of Figure 1; Figure 3 shows a fragmentary view in end elevation in the direction of arrow lil; Figure 4 shows on an enlarged scale a fragmentary transverse section on the line IV--IV of Figure 3; and Figure 5 shows a similar section on the line V-V of Figure 2.

The grating illustrated in the accompanying drawings is of rectangular form and may typically be some 3.6 metres in length and 1.2 metres in width. The grating includes longitudinal side bars 10, (only one of which is seen in Figure 3), and transverse end bars 11, (only one of which is seen in Figure 2). The width of the bars 10 and 11 tapers downwardly somewhat at their inner faces.

A plurality of parallel longitudinal bars 12 extend between the transverse end bars 11 and a plurality of transverse bearing bars 13 extend between the longitudinal side bars 10 so as to intersect and define a grating.

The longitudinal bars 12 and bearing bars 13 taper downwardly at both sides, as can be seen most clearly in Figures 4 and 5. Typically, the width of the end bars 11 and bearing bars 13 at their upper faces may be 7 millimetres and the bearing bars 1 3 may be arranged at centre-tocentre spacings of about 25 millimetres, whilst the side bars 10 and the longitudinal bars 12 may typically have a width at their upper faces of 12 millimetres and be arranged at centre-to-centre spacings of about 100 millimetres.

The bars 10 to 13 are each defined by a plurality of pultruded strips of rectangular crosssection embedded in a synthetic resin which unites said strips to form said bars, which are themselves integrally united to form the grating.

In the illustrated embodiment, the side bars 10 and longitudinal bars 12 each include four such strips, 1 4a to 1 4d, all of equal width. The end bars 11 and bearing bars 13 each include five strips 1 5a to 1 5e, the uppermost two being somewhat wider than the remaining three. The thickness of the strips may typically be between 1 millimetre and 5 millimetres, preferably about 2 millimetres, and the width of the strips is chosen so as to be slightly less than the intended width of the bars themselves so that the strips are wholly embedded when the grating is cast.

The grating illustrated can be manufactured in a mould comprising a tray having a flat bed with upturned edges. Rows of rectangular blocks secured to the flat bed form the rectangular openings of the grating and collectively define mutually transverse intersecting channels for the reception of the pultruded strips.

The strips 1 4a-1 4d and 1 5a-1 5d may simply be cut from stock lengths of pultruded material and laid directly into such channels in the mould and laid directly into such channels in the mould in alternate layers to build up a lattice of inverleaved strips, but preferably, for ease of handling, the strips are assembled together into such a lattice before they are placed in the mould.

For this purpose, the strips are preferably secured together by means which does not involve drilling or penetrating the pultruded material, so as to avoid cutting through the internal fibres and thereby reducing the strength of each strip. Most simply, the strips may be tied together by loops of glass fibre or any other suitable material, or alternatively they may be secured together by spots of an appropriate adhesive at the cross-over points.

When the lattice of strips is arranged in the mould, the latter is filled with a suitable synthetic resin which is then caused or allowed to cure.

It will be understood that the resin rich areas between the pultruded strips will be liable to cracking due to shrinkage during cure. It is therefore preferable to incorporate a suitable filler to reduce exotherm and shrinkage. Such filler should be corrosion resistant and should not unduly increase viscosity. By applying a vacuum to the resin in the mould, entrapped air will be released to ensure a void free moulding in known manner. Whilst such a filler may be desirable it is not necessary to include any additional reinforcing fibres, although, as previously mentioned, such fibres could be incorporated if desired in special circumstances.

Gratings produced in this manner using pultrusions of glass fibre rovings and thermosetting polyester resin embedded in a polyester resin/silica sand mix, have been tested and shown to withstand a limited imposed load of 368 kgs. per square metre, with a maximum downward deflection of 10 mm. over a span of one metre. Further, if such a grating is loaded until failure occurs (as shown by the breakdown in integrity of the resin in which the pultruded strips are embedded) in the compression zone the gratings are sufficiently resilient substantially to recover from such a loading without acquiring any significant permanent deflection.

Since the grating is reinforced in the same manner throughout its entire depth, it may safely be used either way up.

Whilst in the specific example described above, the grating is of relatively large size and of entirely rectangular openwork form, it will be appreciated that the overall size of such a grating may be varied within wide limits, and that the spacing and dimensions of the longitudinal bars 12 and bearing bars 13 may be varied within wide limits.

In particular, the depth and width of the longitudinal bars 12 need not be equal to that of the bearing bars 13, and likewise the depth and width of the side and end bars 10 and 11 need not be the same as those of the bars 12 and 13.

Also, the bars need not be arranged in a rectangular pattern, but could intersect at an acute angle. Likewise, three such sets of bars could be provided in a grating defining triangular or hexagonal apertures, with the outer edge of the grating preferably, but not necessarily, being correspondingly shaped. Again in some instances the end and side bars could be omitted entirely.

In an alternative arrangement, a panel could be formed as a grid including a plurality of spaced parallel bars extending in only one direction and interconnected at or near their ends by respective transverse bars. In such a case, the pultruded strips would be arranged in such bars, and if necessary appropriate distance pieces may be introduced between the pultruded strips in the parallel bars intermediate the transverse bar.

As mentioned previously, the mould in which such a grating is made most conveniently includes a flat base plate and a plurality of appropriately shaped blocks mounted thereon so as to leave channels which define the bars constituting the grating By omitting certain of such blocks, the grating may be formed with one or more solid areas at appropriate locations, or by omitting such blocks entirely, a solid slab could be formed.

Also, a continuous facing deck could be formed above the bars by filling the mould above the tops of the blocks, and in this case the lattice of pultruded strips preferably also extends above the tops of the blocks so as to reinforce the upper layer itself, possibly with additional pultruded strips in the continuous layer arranged between those stacked up in the channels defining the bars, so as further to reinforce that layer. Where such a facing deck is required to extend over only a part, or certain parts, of the whole panel, this may be achieved by incorporating in the mould blocks of reduced height at the appropriate locations so that such blocks are covered with the resin when the mould is filled to the level of the tops of the other blocks.

Any suitable non-slip facing material may be applied to the upper face of the bars or deck afforded by the panel. For example, suitable material may be partially embedded in the resin or adhesively secured thereto. If desired, both upper and lower faces could be so treated to enable a grating to be used either way up.

Whilst the pultruded strips illustrated are of rectangular shape in section, it will be appreciated that other sectional shapes could be employed, such as square or round where appropriate.

Claims

1. A panel structure including a grid of preformed elongated elements each comprising composite fibre/synthetic resin material whereof the fibres are orientated lengthwise of the element and are closely packed together, said grid being embedded in a mouldable synthetic resin.

2. A panel structure according to Claim 1 wherein said mouldable synthetic resin is devoid of other internal reinforcement.

3. A panel structure according to Claim 2 wherein said mouldable synthetic resin includes filler material.

4. A panel structure according to any one of the preceding claims wherein a non-slip facing material is applied to at least one face of the panel structure.

5. A panel structure according to any one of the preceding claims wherein the elongated elements comprise strips of pultruded material formed by wetting the fibres with the relevant resin and drawing them through a die to pack them together and form said composite material.

6. A panel structure according to any one of the preceding claims wherein the fibres comprise glass fibre.

7. A panel structure according to any one of Claims 1 to 5 wherein the fibres comprise carbon fibre.

8. A panel structure according to any one of Claims 1 to 5 wherein the fibres comprise a metal filament.

9. A panel structure according to any one of Claims 1 to 5 wherein the fibres comprise vegetable fibre.

10. A panel structure according to Claim 5 comprising pultruded strips of glass fibre rovings and a thermosetting polyester resin which are themselves embedded in a polyester/silica sand mix.

11. A panel structure according to any one of the preceding claims wherein said elements are arranged in vertically aligned stacks with each element spaced from adjacent elements in the same stack.

12. A panel structure according to Claim 11 wherein said elements are arranged into a lattice comprising a plurality of layers each including spaced parallel elements with the elements in successive layers extending mutually transversely.

13. A panel structure according to Claim 12 comprising a plurality of intersecting mutually transverse bars wherein each bar has one of said stacks of said elements embedded therein.

14. A panel structure according to Claim 11 comprising a grid of parallel bars interconnected at or near their ends by respective transverse bars, wherein each of the bars has one of said stacks of said elements embedded therein.

15. A panel structure according to Claim 13 or Claim 14 wherein the spaces between said bars are open and the panel is in the form of a grid or grating.

1 6. A panel structure according to Claim 13 or Claim 14 comprising at least in part a flat deck portion with said bars at one side thereof.

1 7. A panel structure according to Claim 1 6 wherein the stacks of said elements extend into the thickness of the flat deck portion.

18. A panel structure according to Claim 13 or Claim 14 comprising at least in part of a solid portion wherein the spaces between the stacks of said strips are filled with said mouldable synthetic resin.

19. A panel structure substantially as hereinbefore described with reference to and as shown n the accompanying drawings.