GB2482015A

GB2482015A - A support structure for a pylon

Info

Publication number: GB2482015A
Application number: GB1011925.3A
Authority: GB
Inventors: Justine Rhian Garbutt
Original assignee: Francis and Lewis International Ltd
Current assignee: Francis and Lewis International Ltd
Priority date: 2010-07-15
Filing date: 2010-07-15
Publication date: 2012-01-18
Also published as: GB201011925D0

Abstract

A support structure for a pylon 28, the structure including a grillage frame 10 incorporating a base plate 18 for the pylon and an upstanding retaining wall 24 attached to a side of the frame, the frame including means for securing in the ground to resist lateral loads, the securing means may be screw piles 27. One pile may be driven in at an angle to vertical. The grillage frame may have legs 15 with flanged feet 16, and have cladding 21. The grillage frame may include rolled steel I-beams or girders 13, 14.

Description

Support Structure This invention relates to a support structure typically for use in mounting roadside signs, especially of the type for supporting overhead signs on motorways, where the sign display panel is attached, cantilever-fashion, to a support pylon erected at the side of the motorway.

When structures of the type described are erected especially on sloping ground, the base plate, to which the pylon is attached, is according to current practice secured to a base assembly disposed in a suitably-excavated location, the location having a retaining wall at least at the side adjacent the higher ground level. Typically, the retaining wall is formed either from metal sheet piling or from concrete "L" section castings, where the horizontal part is either disposed facing rearwardly of the location and subsequently covered by back-filled earth for stability, or faces forwardly to prevent the vertical part from tipping forwards under the weight of back-filling. In any event, once the retaining wall has been placed in position and back-filling of earth has taken place, the base assembly may be constructed and the pylon erected, attached to its base plate, commonly formed as part of a grillage frame structure.

In one aspect, the present invention provides a support structure for a pylon, the structure comprising in combination a grillage frame incorporating a base plate for the pylon and an upstanding retaining wall attached to at least one side of the grillage frame, the grillage frame incorporating means for securing in the ground to resist lateral loads applied, in use, to the retaining wall.

Preferably, the means for securing the grillage frame to the ground comprise piles, more preferably screw piles, of which at least one may be driven in the ground substantially vertically and at least another may be inserted at an angle to the first, in order better to resist lateral forces applied to the retaining wall.

Especially when it is intended to erect the pylon on sloping ground, the grillage frame may be supported along one side by legs, to avoid the need for pre-excavation to provide a level sub-base.

The grillage frame preferably comprises longitudinal main beams supported by and bolted to crossbeams which may extend on either side of the main beams in order to support, at their ends, pile support beams for direct engagement with the heads of the piles or, along the side of the lower ground level, direct engagement with the upper ends of the legs which, in turn, are engaged at their feet with the piles. The base plate for the pylon is preferably supported by the central region of the main beams and by plate support beams spanning between and supported by the main beams. Suitable cross-braces or tie beams may be provided where required according to the circumstances of the site concerned, for example diagonally between adjacent pairs of legs or between the lower region of the legs and the pile support beam at the other side of the grillage frame.

The upstanding retaining wall comprises one or more wall panels preferably attached to upright girders which are attached to a suitable grillage frame beam at the rear or "uphill" (in use) side of the assembly. For convenience in attachment, the lower end of each girder may be formed with an end plate which is bolted direct to the flanges of the grillage frame beam, preferably in most situations the rearmost pile support beam.

To resist the beam flanges from deforming under lateral loadings from the back-filled earth behind the retaining wall, stiffening or bracing elements may be applied, for example as webs between the upper and lower flanges of the beam, Preferably, to prevent lateral loads accumulating and building up pressure behind the retaining wall, the wall panels are permeable to water.

The wall panels may be formed from a metal, for example steel, mesh, fitted between adjacent pairs of upright girders with optional intermediate horizontal girders separating upper and lower panels. The panels are preferably backed with a moisture-permeable material such as a geotextile fabric material.

Skirting cladding may be applied to the sides of the grillage frame following its installation, largely for aesthetic reasons, and suitable access steps and peripheral hand rails may be provided as required. Furthermore, the frame may subsequently be used to support control or instrument cabinets for the overhead sign, the pylon for which may be attached to a flanged collar bolted to the base plate of the grillage frame.

Support structures according to the invention may be assembled on site from suitable components according to the local ground conditions. Furthermore, pre-excavation is not necessarily required, as it is with existing structures, and in particular it is not necessary to provide a substantially level base for the structure, before assembly.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings of which: Figure 1 is a perspective view of a grillage frame for use with apparatus according to the present invention; Figure 2 is another perspective view of the grillage frame of Figure 1 with further components attached; Figure 3 is a side elevation of a grillage frame including supporting piles and attached retaining wall according to the invention; and Figure 4 is a side elevation of the assembly of Figure 3, engaged with the ground and carrying an overhead sign.

Figure 5 is a front elevation of the retaining wall of Figure 3; and Figure 6 is a cross sectional fragmentary view along the line VI -VI of Figure 5 showing the attachment of the retaining wall to the grillage frame.

With reference firstly to Figure 1, the apparatus 10 consists essentially of longitudinal main beams 11 in the form of rolled steel I girders supported on and bolted to similar crossbeams 12 which support, at their respective outer ends, pile support beams 13, 14. The pile support beams are also in the form of rolled steel I girders and the pile support beams 14, for use on the "downhill" side of the installation (that is, the lower ground level) are supported on tubular legs 15 with flanged feet 16. The "uphill" beams 13 and the feet 16 of the legs 15, attached to the "downhill" beams 14, are themselves attached to the heads of ground-engaging screw piles (see Figures 3 and 4).

Spanning between the main beams 11, equidistant from the centre thereof, are plate support beams 17 which, together with the upper flanges of the main beams 11, support a base plate 18 for the pylon. Tie bars 19 are provided in diagonal relationship between respective pairs of legs 15 and tie bars 20 are also provided between the feet 16 of the legs and the pile support beams 13.

Referring now to Figure 2, essentially the same apparatus as described with reference to Figure 1 is shown with cladding 21 applied to the periphery of the grillage frame, access stairs 22 and a flanged collar 23 bolted to the base plate 18, itself for attachment of the pylon.

In Figure 3, the grillage frame 10 has attached to the rear or "uphill" side thereof an upstanding retaining wall 24 and is provided with a hand rail 25. Cabinets 26 for electronic control equipment and the like are also provided on the grillage frame 10.

The grillage frame is supportd by ground-engaging screw piles 27.

Figure 4 shows the installation as described with reference to Figure 3 secured in place on sloping ground with minimal pre-excavation having been carried out to prepare the site. The grillage frame carries a pylon 28 and an overhead sign 29, supported cantilever-fashion from the upper end region of the pylon 28.

Figure 5 shows the retaining wall 24 of Figures 3 and 4 as a front elevation. The wall consists of rectangular steel mesh panels 30 supported between upright girders 31 bolted to a longitudinal beam, such as beam 13, of the grillage frame. Intermediate lateral brace girders 32 may be provided between adjacent pairs of upright girders 31.

The panels are backed by a geotextile fabric material (not shown).

Figure 6 shows the base portion of an upright girder 30 of the retaining wa1124, provided with a welded end plate 33 and bolted to the upper flanges of beam 13.

Stiffener plates 34 are welded between the upper and lower flanges of beam 13 to enable the beam to withstand buckling under pressure from behind the retaining wall.

Claims

Ctaims 1. A support structure for a pyion, the structure comprising in combination a grillage frame incorporating a base plate for the pylon and an upstanding retaining wall attached to at least one side of the grillage frame, the grillage frame incorporating means for securing in the ground to resist lateral loads applied, in use, to the retaining wall.
2. A support structure according to claim 1, in which the means for securing the grillage frame to the ground comprise piles, preferably screw piles.
3. A support structure according to claim 2, in which at least one of the piles is driven in the ground substantially vertically and at least another is inserted at an angle to the first.
4. A support structure according to any preceding claim, in which the grillage frame is supported along one side by legs.
5. A support structure according to any preceding claim, in which the grillage frame comprises longitudinal main beams supported by and bolted to crossbeams which optionally extend on either side of the main beams sand support, at their ends, pile support beams for direct engagement wit the heads of the piles or, along the side of a lower ground level, direct engagement with the upper ends of the legs which, in turn, are engaged at their feet with the piles.
6. A support structure according to claim 5, in which the base plate for the pylon is supported by the central region of the main beams and by plate support beams spanning between and supported by the main beams.
7. A support structure according to any preceding claim, in which the upstanding retaining wall comprises one or more wall panels which may be attached to upright girders attached to a grillage frame beam at the rear of the assembly.
8. A support structure according to claim 7, in which the wall panels are permeable to water.
9. A support structure according to claim 8, in which the wall panels include a moisture-permeable material such as a geotextile fabric material.
10. A support structure according to any preceding claim and including skirting cladding applied to the sides of the grillage frame, access steps and peripheral hand rails as required.
11. A support structure according to any preceding claim assembled on site from suitable components according to local ground conditions.
12. A support structure substantially as herein described with reference to and as illustrated in any of the accompanying drawings.