COMPOSITE GROUND BEAMS

This invention concerns the design of a ground beam.

Ground beams are elements of structure set at ground level. They are designed to support loads and usually span between foundations. Traditionally the beams would be cast in-situ or pre-cast from concrete. These are strong but are relatively heavy and difficult to construct. For lighter loads such as those found when supporting domestic property a more economical lighter solution is required.

Steel can be used but there are corrosion problems when set in the ground. Plastic can be extruded or bent into the required shape of a ground beam, is economical, easily worked and does not corrode. Plastic has a low modulus of elasticity which means that deflection of the supporting member can be excessive.

Where ground beams are prefabricated, the ends are generally cut to suit the profile of the finished beam and contain holes to allow for bolted connections. These can be difficult to construct and a more economical, simpler solution is required

In a first aspect of this invention a profile member has a core of filler material. The profile member may be plastic, typically reinforced plastic. The filler material may be concrete (or a grout) . The profile member would usually be of either a 'U' or a 'box' profile but may also be extended with one or more other external projections/additions depending on its function. Ina preferred embodiment, the in-filled profile member forms a ground beam.

Preferably, the inside of the 'U' or 'box' profile has one or more additional internal connecting projections/ribs to enhance the bond between the filler and the profile member.

The composite section can be further strengthened by adding one or more reinforcing bars of, for example, steel. In this case a thinner plastic (or other suitable material) could be used and the full load would be taken by the concrete/grout/reinforcing infill.

In a second aspect of the invention a ground beam comprises a hollow sleeve in-filled with a filler material. The filler material may be concrete or grout. The sleeve may be of U-section or box section.

The sleeve may be made of any suitable materials including plastics, optionally reinforced plastics or metals such as aluminium. The sleeve may be load bearing. Alternatively, the sleeve may be non load bearing.

In a third aspect of this invention members (connectors) are pre-fabricated so that straight interconnecting members can be connected together by joining them onto the prefabricated connectors. This allows corners/junctions to be constructed with a series of preformed connectors and straights so that complex plans/arrangements can be achieved in a simple manner.

The connectors would generally have a push (friction) fit with the straight members. The strength of the connection could however be increased with mechanical fixings such as bolts or pins.

Where the members are connected from hollow members, the strength of the joint could be increased by filling the member with concrete or grout.

The joint could be further strengthened by adding reinforcement to the concrete.

In one application the ground beam is supported on piles set into the ground. If the top of the pile is made from steel this can be subject to corrosion in the disturbed soil or void below the ground beam.

Thus, in a fourth aspect of this invention the top of the pile can be protected by providing a plastic or other non corrosive material around the pile head.

Suitable materials that can be used include, for example, glass reinforced plastic (GRP) or similar composite material.

The protective material may be provided in the form of a head tube that can be driven around the pile head section. The protective head tube may also increase the lateral resistance of the pile and increase its bending resistance.

Any gap between the pile head section and the protective head tube can be in-filled with grout or resin or another similar material to connect the pile head section and pile head tube together. Alternatively the pile head section and pile head tube could be mechanically fixed together.

The top of the protective head tube can be fitted with an adjustable head to allow for, vertical and/or horizontal and/or rotational adjustment. This allows the head tube to be set in the correct position before fixing the ground beam.

The invention in each of these aspects will now be described in more detail by way of example only with reference to the accompanying

drawings in which like reference numerals indicate corresponding parts and wherein:

Figure 1 shows a composite section of U profile in accordance with this invention

Figure 2 shows a composite section of box profile in accordance with this invention

Figure 3 shows a modification to the composite section of box profile of Figure 2 with additional projection

Figure 4 shows a modification to the composite section of box profile of Figure 2 with additional internal projections

Figure 5 shows a modification to the composite section of box profile of Figure 2 with steel reinforcing bars

Figure 6 shows a traditional welded connection.

Figure 7 shows a traditional bolted connection.

Figure 8 shows a connection in accordance with this invention.

Figure 9 shows a connection in accordance with this invention.

Figures 10 and 11 show a pile fitted with a protective head tube in accordance with the invention.

Referring to the drawings, Figure 1 shows a composite section consisting of a profile member 1 of U-section, preferably a plastic profile, and an

infill 2 of, for example, concrete or grout. The profile member 1 retains the infill 2 and generally provides the main tensile strength of the section. The infill 2 preferably fills the U-section forming a solid core that generally provides the main compressive strength and reduces the deflection of the section.

Figure 2 shows a composite section consisting of a profile member 3 of box section and an infill 2. The profile member 3 may be plastic and the infill 2 may be concrete or grout and preferably fills the box-section forming a solid core as in the previous embodiment.

Figure 3 shows the composite section of Figure 2 with the profile member 3 extended with external projection 5. The projection 5 provides support to elements of structure such as the external skin of brickwork, floor or secondary beams. More than one external projection may be provided.

Figure 4 shows the composite section of Figure 2 with internal projections 7. The internal projections 7 increase the bond between the infill 2 and the profile member 3 They also increase the tensile capacity of the profile. One or more internal projections may be employed. The internal projections could be large as shown or a larger number of small projections.

Figure 5 shows the composite section of Figure 2 with an additional reinforcing bar 8 constructed from either GRP or steel. The reinforcing bar increases the strength of the section. More than one reinforcing bar may be provided.

Figure 6 shows a traditional prior art welded connection for a section of box profile. Box members 9 and 10 are cut to profile and joined by a weld 11.

Figure 7 shows a traditional prior art bolted connection for an I-beam profile. I-beam members 12 and 13 are cut to form the joined profile and connected using an angle bracket 14 and bolts 15.

Figure 8 shows two members of box profile connected in accordance with the invention. Member 16 is a preformed corner piece constructed, for example, from GRP, plastic or aluminium. Straight members 17 and 18 are then connected onto this corner piece to form the junction. As shown, member 16 contains projections that are a push fit inside the box profile of straight members 17 and 18. The members could also be glued, bolted or screwed in position. Connector members may be configured to form a range of joints between profile members, for example straight joints, elbow joints, T-joints, allowing ground beams to be assembled to any desired pattern.

Figure 9 shows a similar connection to Figure 8 where the members to be connected are of an I-beam profile and have a thin vertical web. A preformed connector 19 constructed, for example, from GRP, plastic or aluminium connects straight members 20 and 21. Projections 22 and 23 on the connector 19 fit around the webs 24 and 25 of I beams 20 and 21. The connection could be a push fit, glued, screwed or bolted.

Figures 10 and 11 show a pile 27 provided with a protective head tube 26 in accordance with the invention. The head tube 26 which is made, for example, of non-corrosive material such as plastics is set around the head section of the pile 27 and the gap therebetween is infilled with filler 28, for example, grout. An adjustable head 29, 30 is fitted onto the top of the head tube 27. Top section 29 screws into the lower section 30 to give vertical adjustment. Any other means of providing vertical adjustment may be employed. In another embodiment (not shown) , the adjustable

head may provide for one or more of vertical, horizontal and angular adjustment.

Although the profiles shown in Figures 1-9 would usually be plastic, a glass reinforced plastic (GRP) or another similar composite profile consisting of a high performance fibre (glass, carob or aramid) in a polymer matrix (polyester, vinylester, epoxy or phenolic) could also be used. If a material that is stronger than plastic, such as GRP is used the section may have sufficient strength to work without the concrete/grout infill.