BUILDING STRUCTURE AND METHOD OF MAKING IT

Abstract: A building structure comprises a hollow core (2), preferably made of a plastics material, on the outer surface of which is wound a fibre layer (3), an outer layer (4) of plastics material being provided outside the fibre layer (3). The structure may be used as the basis of a pile or as a retaining wall in which case the outer layer is preferably made rectangular and provided with clutches enabling the structure to be connected to other such structures, which, when in the ground, may have the hollow cores filled with concrete.

Description: BUILDING STRUCTURE AND METHOD OF MAKING IT This invention relates to improvements in building structures (including building components), particularly building structures such as piles, and to a method of making a building structure. Many different types of piles exist, but most suffer from one or more drawbacks. The traditional materials are wood, concrete or steel. Wood is expensive, rots and may be attacked by marine boring animals. Wood is not favoured ecologically for reasons of forest preservation, and chemical treatments such as creosote can harm the environment. Steel rusts over a period of time, particularly in marine environments. Steel and concrete are expensive and heavy and suffer from chemical attack and corrosion in contaminated or marine environments. It has been known to substitute wood and steel piles with other material such as solid piles formed from recycled plastic reinforced with GRP rods. These have good fendering qualities and a long life, but are heavy to transport, are flexible, and stress cracks can appear as a result of the manufacturing processes used. Steel pipes have been used, but these are expensive to produce due to the moulds required. Sheets piles are often used for creating walls, particularly in marine environments for building wharfs and the like. Such sheet piles are usually formed from elongate metal sheets with a clutch along each long edges which can engage with the clutch on the edge of adjacent sheet to create a wall of sheet piles. The sheet piles are often anchored into the adjacent ground, as they do not on their own provide a strong wall. Disadvantages with such sheet piles include corrosion, especially in marine or contaminated environments, that they can fall away if they are not well anchored to the ground behind, and the clutches holding two adjacent sheet piles together do not have much intrinsic strength and can break. The invention seeks to provide a building structure which may, inter alia, be in the form of a pile which obviates or mitigates the above problems. According to the present invention there is provided a building structure comprising a tubular core having a fibre layer as its outer surface, and an outer layer of plastics formed on the fibre layer. The tubular core may comprise the fibre layer supported internally by a number of rods. The building structure may be adapted to have its core filled with filler material such as concrete. The hollow tubular core may be circular or rectangular in cross section. The hollow tubular core may be formed from medium density polyethylene (MDPE) The fibre layer may be formed from fibres of glass, carbon, Kevlar, or polyester or mixtures thereof. The fibre layer may include a resin. The outer layer may be formed from resin plastics or recycled plastics. The outer layer may be reinforced. The building structure may be in the form of a pile. The pile may have a steel or concrete tip at one end to facilitate driving the pile into the ground. The pile may be adapted to receive a driving dolly through the hollow core which engages with the tip when the pile is being driven. The building structure may include connection means to interconnect two or more building structures together. The connection means may be in the form of a tongue and groove on each structure or clutches such as used on sheet piles. At least part of the outer layer may be UV stabilised. The outer layer may have a first inner body of plastics not UV stabilised and an outer body UV stabilised. The outer body may also be coloured. The present invention also provide a method of making a building structure as defined in any of the last ten preceding paragraphs, the method comprising forming the hollow core, winding the fibre layer on the core, and extruding the outer layer on the fibre layer. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 shows a part cut away side view of a first embodiment of a building structure according to the present invention filled with concrete; Fig. 2 shows a view of the building structure of Fig. 1 in the form of a pile; Fig. 3 is a perspective view of a second embodiment of the present invention; Figs. 4A to 4E show in schematic cross section how a number of the structures of Fig. 3 may be interconnected; and Fig. 5 illustrates the manufacture of a rod for use in the core of the second embodiment of the present invention. Referring to Figure 1 there is shown a first embodiment of a building structure 1 according to the present invention. The structure 1 has a hollow tubular core 2 of plastics material. The core 2 may be extruded using medium density polyethylene (MDPE) and, whilst shown circular in cross section, may be of any other shape such as rectangular. A fibre layer 3 is bonded to the outer surface of the core 2. The fibre layer 3 may be formed from fibres of glass, carbon, Kevlar, or polyester or mixtures thereof, and may include a resin. The fibre layer 3 may be spiral wound on the core 2. An outer layer 4 of plastics is formed on the fibre layer 3. The outer layer 4 may be formed from recycled plastics. The inner part 4B of the layer 4 may be of any suitable plastics but an outer part 4A of the layer 4 may be coloured and contain UV stabilisers. Alternatively the entire outer layer 4 could be coloured and/or UV stabilised. Furthermore, the outer layer may include additional reinforcement such as with glass fibre or metal bars or glass fibres or combinations thereof. The core 2 is filled with a filler material such as concrete or foamed concrete 5, and may include additional reinforcement such as steel bars. The building structure 1 may be made by extruding the tubular hollow core 2, winding and heat curing the fibre layer 3 on the core, and extruding the outer layer 4 on the fibre layer 3. The fibre layer 3 may be applied by moving the core through a fibre winding station, and then passing the core and fibre layer through a heat curing station. As shown in Figure 2, the building structure according to the present invention may be in the form of a pile 11. The pile 11 has a pile body having a plastics core 12, fibre layer 13, and an outer layer 14 of recycled plastics (optionally coloured and/or UV stabilised) similar to the structure 1 of Figure 1. The pile may have a steel tip 15 at one end to facilitate driving the pile into the ground. The pile may be adapted to receive a driving dolly 16 through the hollow core 12 which engages with the steel tip when the pile is being driven. After the pile has been driven onto the ground and the dolly 16 withdrawn, the hollow core 12 may be filled with filler material such as concrete or foamed concrete. The building structure may include connection means to interconnect two or more building structures together. For example, the building structure could be a "plank" and the connection means could be in the form of a tongue and groove so that two or more such planks could be joined together. Alternatively the building structure could be a sheet pile with clutches which can interlock with clutches on another sheet pile so that two or more sheet piles can be joined together and the sheet pile may have a number of cores of circular cross section, as will be described in more detail herein. It has been found that the fibre layer gives great strength to the core upon which it is wound, and when filled with concrete, the fibre layer prevents the core from expanding which may increase the ability of the concrete to accept compressive loads. The winding angle of the fibres relative to the core may be varied to create particular characteristics in the performance of the structure. For example with a structure filled with concrete it may be desirable to wind fibres substantially normal to the longitudinal axis of the core in order to restrict the expansion of the core. Alternatively it may be desirable to wind some of the fibres substantially parallel to the longitudinal axis of the core, e.g. to create particular characteristics in the performance of the structure, such as flexibility. Referring to Figs 3 and 4, there is shown a building structure in the form of a pile 31 having an elongate structure 32 of generally rectangular cross-section. Pile 31 has two opposing length sides 32A, 32C and two width sides 32B, 32D. The length sides 32A, 32C are twice the dimension of the width sides 32B, 32D. Two adjacent sides 32A, 32B of pile 31 each have first connection means in the form of T-shaped projections 33 of identical size running the length of the pile 31. Two projections 33 are provided on length side 32A and one projection 33 is provided on width side 32B. The other two adjacent sides 32C, 32D each have second connection means in the form of T-shaped recesses 34 running the length of the pile 31. Two recesses 34 are provided on length side 32C and one recess 34 is provided on width side 32D. The size of each projection on any pile is such that it can fit snugly into and be retained by a recess of another pile. The projections and recesses act as "clutches". Referring to Fig. 4A it will be seen that a wall can be created by joining a plurality of piles 31 together lengthways with a projection from each pile width side engaging with a recess in another pile width side. The width of the wall created is thus the width side dimension of a pile. Two piles 31 are joined by lowering one down the side of another, e.g. with a crane, with the projection of one sliding down the recess of another. Referring to Fig. 4B it will be seen that a wall can be created by joining a plurality of piles 31 together widthways with both projections from each pile length side engaging with recesses in another pile length side. The width of the wall created is thus the length side dimension of a pile. Referring to Fig. 4C it will be seen that a double wall can also be created, with overlapping joints. From Fig. 4D it will be seen that a wall can be created with joining a plurality of piles alternatively in the lengthways and widthways orientation, and in Fig. 4E it will be seen that a wall can be created which turns through 90 degrees. The T-shaped projections are preferably relatively substantial so as to provide them sufficient sheer strength so that two adjoining piles do not easily separate under load. Referring again to Fig. 3, the pile 31 is, in this embodiment, formed by taking a pair of hollow tubular cores 35 A, 35B of plastics material (such as plastic pipe) each with a fibre layer bonded to the outer surface, and forming an outer layer of plastics over the pipes 35A, 35B to create the structure with a generally rectangular cross-section. Alternatively the cores 35 A, 35B could be formed of one or more steel or glassfibre solid or hollow rods surrounded by the fibre layer. The outer layer of plastics need not have great strength and could be formed of recycled plastics, e.g. extruded. Solid metal or glassfibre rods would most conveniently be made by the pultrusion process. Typically, a number of rods, usually about 6, 8 or 12, are formed on a continuous basis, their centres being on a circle, and as they are formed they are wrapped in unidirectional glassfibres spiral wound in opposite directions at angles of between 75° and 90°. The tube thus formed is impregnated with resin and passed through a heat curing station in the form of an oven to cure the resin. As seen in Fig. 5, solid glassfibre rods are formed by taking a number of fibres 51, usually in the range 20-30, huddling them in a circular former 52, and then passing the fibre bundle into a resin bath 53 where they pass beneath a roller 54 to ensure that the bundle of fibres is impregnated with resin. A group, usually between 10 and 14, of the impregnated fibre bundles is located with the centres of the bundles on a circle and passes through a wrapping station 55 where the group is spiral wrapped with glassfibres, the bundle then passing to an oven 56 where the resin is cured. Instead of using glassfibres as the wrapping medium polyester or carbon fibres could be used as could mixtures of these fibres. The invention may take a form other than that specifically described above. For example the first and second connection means could be other than projections and recesses and different numbers of them could be provided. The structure of the invention could be square in cross section, or the length side may be other than twice the dimension of the width sides. If desired structures other than straight walls could be built. For example piles 1 could be joined together alternatively with triangular structures (with suitable first and second connections means) so as to change the direction of the wall through less than 90 degrees, e.g. to form multi-sided pillars such as hexagonal or octagonal pillars. The structure of the invention may be used for many different purposes, such as building walls like marine wharfs, foundations, or even creating buildings.

Claims: CLAIMS 1. A building structure comprising a tubular core having a fibre layer as its outer surface, and an outer layer of plastics formed on the fibre layer. 2. A building structure as claimed in claim 1 , in which the tubular core comprises the fibre layer on a plastics tube. 3. A building structure as claimed in claim 1, in which the tubular core comprises the fibre layer supported internally by a number of rods. 4. A building structure as claimed in claim 3, in which the rods are glassfibre rods. 5. A building structure as claimed in claim 3, in which the rods are made of metal.. 6. A building structure as claimed in any preceding claim, in which the outer layer has a generally rectangular cross-section. 7. A building structure as claimed in claim 6, in which he fibre layer is formed from fibres of glass, carbon, or polyester or mixtures thereof. 8. A building structure as claimed in claim 6 or claim 7, in which two adjacent sides of the structure each having a first connection means and the other two sides each having a second connection means, whereby a first connection means on one side of one structure can engage with a second connection means of another structure so that two or more tubes can be joined together to create a wall.. 9. A building structure as claimed in any of claims 6 to 8, in which the dimension of the length of the rectangular cross section of the structure is twice the width. 10. A building structure as claimed in any of claims 6 to 9, in which one length side has two first connection means and an adjacent width side has one first connection means, and the other length side has two second connection means and an adjacent width side has one second connection means. 11 A building structure as claimed in claim 10, in which the first connection means is a projection to engage in a second connection means in the form of a recess. 12. A building structure as claimed in claim 11, in which the projection is generally T- shaped and the recess a T-shaped recess to receive the T-shaped projection. 13. A building structure as claimed in any preceding claim, in which the core is filled with a filler material such as concrete. !4. A building structure as claimed in any of claims 1 to 12, in the form of a pile . having a steel or concrete tip at one end to facilitate driving the pile into the ground 15. A building structure as claimed in claim 14, in which the pile is adapted to receive a driving dolly through the hollow core which engages with the tip when the pile is being driven. 16 A method of making a building structure as claimed in any preceding claim, comprising forming the hollow core, winding the fibre layer on the core, and extruding the outer layer on the fibre layer. 17. A method as claimed in any claim 16, including impregnating the fibre layer with resin and then passing the core and fibre layer through a heat curing station.

Inventors: LANG DOMHNALL, LANG, DOMHNALL
Applicants: LANG DOMHNALL, LANG, DOMHNALL
Application year: 2000
Main classification: E02D5
IPC codes: E02D5