Structure-foot reinforcement apparatus

Abstract

A structure-foot reinforcement apparatus 10 is provided for reinforcing damaged or weakened feet of structures. A plurality of reinforcement struts 14 is provided, each comprising a base portion 18 having a contact area 20 configured to in-use directly or indirectly contact a flange (22 fig 4) of a foot 12 of a structure to be reinforced. An upper portion 24 is spaced apart from the base portion 18 in an in-use vertical direction, and an anchor portion 26 is spaced from the contact area 20 in an in-use horizontal direction. This permits connection of the reinforcement strut 14 to a structure foundation 28. There is also a strut connector 36 engageable with the upper portions 24 of the plurality of reinforcement struts 14 in-use to interconnect them, the strut connector 36 having a multi-part body (38a, 38b fig 5) to be receivable around the foot 12 of the structure to be reinforced.

Description

The present invention relates to a structure-foot reinforcement apparatus particularly but not necessarily exclusively for reinforcing the feet of a tower or the base of a monopole. The invention further relates to a method of reinforcing a damaged or weakened foot of a structure having a base flange, preferably using the aforementioned apparatus. A problem with structures such as towers and monopoles is that, over time, existing anchors or embedment steel becomes corroded or degraded in some form. Additionally, some structures may require strengthening, for instance, where additional capacity is required. Any solution must provide a means of reinforcing a structure either in compression or in tension or against bending moments, depending on the structure type. It is an object of the present invention to reduce or substantially obviate the aforementioned problems. According to a first aspect of the invention, there is provided a structure-foot reinforcement apparatus comprising: a plurality of reinforcement struts, each of the reinforcement struts comprising a base portion having a contact area configured to in-use directly or indirectly contact a flange of a foot of a structure to be reinforced, an upper portion spaced apart from the base portion in an in-use vertical direction, and an anchor portion spaced from the contact area in an in-use horizontal direction and which permits connection of the reinforcement strut to a structure foundation; and a strut connector engagable with the upper portions of the plurality of reinforcement struts in-use to interconnect the plurality of reinforcement struts, the strut connector having a multi-part body to be receivable around the foot of the structure to be reinforced. The apparatus works by having reinforcement struts which can be spaced around the foot to be reinforced, with a balancing connector provided to better distribute the forces, either tension or compression, through the various struts and thereby strengthen the structure as a whole. For tower legs which are in tension, vertical and horizontal members of the reinforcement struts will be in compression, with a diagonal side strut being in tension. The strut connector then acts as a tension ring, balancing opposite sides of the apparatus. For a monopole, which experiences bending forces, anchors on one side will be in tension, and anchors on the other in compression. The strut connector again provides balance here. Overall, tension in the structure itself is transferred to the foundation via the apparatus, bypassing the degraded or corroded existing foot. Optionally, the strut connector may form an annulus when assembled. A complete ring around the foot of the structure allows the forces applied to the reinforcement struts to be more readily spread to the other of the plurality of reinforcement struts. Preferably, a plurality of said strut connectors may be provided, wherein joins of the multi-part bodies of the plurality of strut connectors are offset to one another. To provide an annulus which can be installed at ground level, it becomes necessary to have a multi-part body which can be secured together. The weakening of the connector can be mitigated by providing more than one such connector, stacked so that the joins do not align. The structure-foot reinforcement apparatus may further comprise a flange-contact plate configured to directly contact the flange of the foot of the structure to be reinforced in-use, the contact areas of the plurality of reinforcement struts being engagable with the flange-contact plate. A flange-contact plate has the advantage of spreading the forces applied to the apparatus across all of the reinforcement struts at the flange. This provides a more secure anchoring of the apparatus. Optionally, the flange-contact plate may have a multi-part body to be receivable around the foot of the structure to be reinforced. The flange-contact plate may form an annulus when assembled. Preferably, a plurality of said flange-contact plates may be provided, wherein joins of the multi-part bodies of the plurality of flange-contact plates are offset to one another. The flange-contact plate may comprise at least one flange-anchor connector for engagement with an existing anchor of the foot of the structure to be reinforced. Improved securing of the apparatus with respect to the foot can be achieved using the existing anchors, and the flange-contact plate can be dimensioned accordingly. Notably, if a multi-part body is provided, then the flange-contact plate(s) can be installed in part, so that the anchors can be disengaged in sequence, rather than all at once. Each of the plurality of reinforcement struts may comprise a flat base portion having the anchor portion thereon. A flat base portion allows for secure clamping onto the upper surface of an existing flange of the foot. Optionally, the anchor portion may comprise at least one fastener receiver aperture. The anchor portion is designed to engage with a ground anchor, such as a micropile or chemical anchor, and thus has a corresponding aperture for this purpose. Preferably, the upper portion may comprise at least one fastener receiver. The reinforcement struts are designed to be securely fastened to the strut connector, and this will typically be achieved using bolts. Each of the plurality of reinforcement struts may comprise a vertical reinforcement member. Vertical reinforcement members can withstand compressive forces without buckling. Preferably, the vertical reinforcement member may be or substantially be triangular. The provision of a triangular strut provides reinforcement against tension forces, which provides a strong and stable base when the forces are distributed by the strut connector across all of the reinforcement struts. Two said vertical reinforcement members may be provided either side of the base portion. Spacing the vertical reinforcement members apart from one another provides a region therebetween via which fasteners can be easily introduced and fixed into place, without blocking the access for tightening tools. Preferably, the strut connector may have a polygonal symmetry equal to a number of reinforcement struts provided. A highly rotationally and / or linearly symmetric apparatus provides the most uniform distribution of force across the various reinforcement struts, lowering the risk of catastrophic failure. Optionally, the upper portion may comprise a clamping plate. A clamping plate provides a clean flat surface onto which the strut connector can be placed to be supported whilst being fastened into position. The structure-foot reinforcement apparatus may further include an earthing lug. An earthing lug provides an easy means of grounding the apparatus, since it will typically be formed from a conductive material. According to a second aspect of the invention, there is provided a method of reinforcing a damaged or weakened foot of a structure having a base flange, the method comprising the steps of: a] positioning a plurality of reinforcement struts around the foot of the structure such that a contact area of a base portion of each reinforcement strut directly or indirectly contacts the flange; b] positioning a strut connector having a multi-part body around the foot of the structure so as to contact an upper portion of each of the plurality of reinforcement struts; c] securing the strut connector with each of the plurality of reinforcement struts so as to interconnect the plurality of reinforcement struts; and d] at an anchor portion of each of the plurality of reinforcement struts which is spaced from the contact area in an in-use radial direction, securing the plurality of reinforcement struts to a structure foundation. Using this method, weak anchor points of the original structure can be bypassed, reinforcing or strengthening the structure as a whole using the proposed apparatus. This method can also be used with base flange towers where the existing steel stubs in the ground have corroded or otherwise become damaged or weakened. The method may further comprise a step prior to step a] of contacting a flange-contact plate with the flange of the foot of the structure to be reinforced, the contact areas of the plurality of reinforcement struts being engagable with the flange-contact plate. Optionally, the plurality of reinforcement struts may be uniformly spaced around the foot of the structure to be reinforced. Uniform spacing of the struts allows for forces to be evenly distributed, reducing the effects of non-uniform compression or tension about the foot of the structure which might further weaken the original anchor. The method may further comprise a step subsequent to steps b], c], and d] of grouting around the foot of the structure. Grouting the void area between the structure and the apparatus prevents the collection of detritus and standing water, reducing the risk of corrosion or degradation of the apparatus overtime. For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a perspective representation of a first embodiment of a structurefoot reinforcement apparatus in accordance with the first aspect of the invention in an installed condition with a foot of a tower; Figure 2 shows a perspective representation of the structure-foot reinforcement apparatus of Figure 1 omitting the structure, foundation, and grouting; Figure 3 shows a plan view of the structure-foot reinforcement apparatus of Figure 2; Figure 4 shows a side view of the structure-foot reinforcement apparatus of Figure 1 omitting the grouting; Figure 5 shows an exploded perspective view of the structure-foot reinforcement apparatus of Figure 1; Figure 6 shows a side view of the structure-foot reinforcement apparatus of Figure 1, indicating the forces applied thereto; Figure 7 shows a perspective representation of a second embodiment of a structure-foot reinforcement apparatus in accordance with the first aspect of the invention in an installed condition with a monopole tower; and Figure 8 shows a side view of the structure-foot reinforcement apparatus of Figure 7, showing the force balancing relative to the monopole. Referring firstly to Figures 1 and 2 there is shown a structure-foot reinforcement apparatus, referenced globally at 10, and which is suitable for reinforcement of damaged or weakened feet of structures such as towers and pylons. Here, the structure-foot reinforcement apparatus 10 is installed around a foot 12 of a tower to be reinforced. The structure-foot reinforcement apparatus 10 comprises a plurality of reinforcement struts 14, here arranged in a pentagonal configuration, uniformly spaced about foot 12. One of the reinforcement struts 14 is shown engaged with an earthing lug 16 to allow for grounding of the structure-foot reinforcement apparatus 10. Each of the reinforcement struts 14 comprises a base portion 18 having a contact area 20, most readily visible in Figure 3, which is configured to in-use directly or indirectly contact a flange 22 of the foot 12 of a structure to be reinforced. Each of the reinforcement struts 14 also has an upper portion 24 spaced apart from the base portion 18 in an in-use vertical direction, and an anchor portion 26 spaced from the contact area 20 in an in-use horizontal direction and which permits connection of the reinforcement strut 14 to a structure foundation 28. The anchor portion 26 may be part of a unitary and / or flat base portion 18, or, as shown, a separate component spaced apart from the contact area 20 to collectively form the base portion 18. The anchor portion 26 comprises at least one fastener receiver aperture; in this case, the fastener receiver apertures engage with micropiles 30 embedded into the structure foundation 28. This is most evident in Figure 4. Said micropiles 30 will be anchors which fix the structure-foot reinforcement apparatus 10 in tension. Each of the plurality of reinforcement struts 14 comprises a vertical reinforcement member 32, which is provided here as two said vertical reinforcement members 32 provided either side of the base portion 18. The vertical reinforcement members 32 are substantially triangular, with a central void space to reduce the weight of the structurefoot reinforcement apparatus 10. The upper portion 20 may be provided as a clamping plate welded atop the vertical reinforcement members 32, thereby providing a space between the vertical reinforcement members 32 via which tool access is provided for fastening bolts or other fasteners. In the vertical reinforcement members 32, a central upright member 34a and the bottom member 34b will be in compression, whilst the diagonal member 34c thereof will be in tension. A strut connector 36 is also provided which is engagable with the upper portions 24 of the plurality of reinforcement struts 14 in-use to interconnect the plurality of reinforcement struts 14. The strut connector 36 is provided having a multi-part body 38a, 38b so as to be receivable around the foot 12 of the structure to be reinforced. This is a two-part body 38a, 38b which come together to form an annulus, and which are coupled together at one or more of the upper portions 24. The strut connector 36 ideally has a polygonal symmetry equal to a number of reinforcement struts 14 provided. Coupling between the strut connector 36 and the plurality of reinforcement struts 14 is provided by a plurality of fasteners, typically nuts and bolts. The upper portion 24 comprises at least one fastener receiver to accommodate this. The contact areas 20 may directly contact the flange 22 of the foot 12 thereby providing a plurality of circumferentially spaced retaining members on the flange 22. However, preferably there is provided a flange-contact plate 40 configured to directly contact the flange 22 of the foot 12 of the structure to be reinforced in-use, the contact areas 20 of the plurality of reinforcement struts 14 being engagable with the flange-contact plate 40. This allows for spreading of the applied force around the flange 22. Similar to the strut connector 36, the flange-contact plate 40 may have a multi-part body 42a, 42b so as to be receivable around the foot 12 of the structure to be reinforced. Together, the two parts 42a, 42b form an annulus when assembled. Figure 5 shows in detail how the apparatus 10 is assembled. Two strut connectors 36, 36’ are provided, stacked on top of one another, with the joins of the multi-part bodies 38a, 38b, 38a’, 38b’ of the plurality of strut connectors 36,36’ being offset to one another. This inhibits dislocation of the strut connectors 36, 36’ when under tension. Similarly, two flange-contact plates 40, 40’ are provided, also stacked. The joins of the multi-part bodies 42a, 42b, 42a’, 42b’ of the flange-contact plates 40, 40’ are offset to one another. This inhibits dislocation of the flange-contact plates 40, 40’ when in compression. Each reinforcement strut 14 is connected to the strut connectors 36, 36’ by four bolts, and to the flange-contact plates 40, 40’ by four bolts. The lower of the flange-contact plates 40’ here has a plurality of inwardly-extending land portions 44, on which is provided a flange-anchor connector for directly engaging with the existing flange anchors 46 of the flange 22 of the foot 12. This improves the engagement between the structure-foot reinforcement apparatus 10 and the flange 22. To reinforce a damaged or weakened foot of a structure having a base flange, the present invention can be implemented as follows. A plurality of reinforcement struts 14 are positioned around the foot 12 of the structure such that the contact area 20 of the base portion 18 of each reinforcement strut 14 directly or indirectly contacts the flange 12. The strut connectors 36, 36’ are then positioned around the foot 12 of the structure so as to collectively contact the upper portion 20 of each of the plurality of reinforcement struts 14. The strut connectors 36, 36’ are then engaged with each of the plurality of reinforcement struts 14 so as to interconnect the plurality of reinforcement struts 14. At the anchor portion 26, each of the plurality of reinforcement struts 14 is secured to a structure foundation 28. Note that the sequence of the fastening of the components to one another may not necessarily be performed in this order. The reinforcement struts 14 may be engaged with the structure foundation 28 prior to the engagement with the strut connectors 36, 36’ for instance. Where one or more flange-contact plates 40, 40’ are provided, these are contacted with, and preferably secured to, the flange 22 of the foot 12 of the structure to be reinforced, prior to the positioning of the contact areas 20 of the plurality of reinforcement struts 14 thereon. Preferably, the plurality of reinforcement struts 14 is uniformly spaced around the foot 12 of the structure to be reinforced, thereby providing uniform reinforcement around the circumference of the structure. Grout 48 can then be performed to fill any gaps between the structure-foot reinforcement apparatus 10 and the foot 12. In Figure 6, the forces on the structure-foot reinforcement apparatus 10 can be seen. The newly fixed anchors of the reinforcement struts 14 will be in tension, counteracting the tension on the leg of the structure. Figure 7 shows an alternative embodiment of a structure-foot reinforcement apparatus, referenced globally at 110, and which is suitable for use with a monopole, which will be subject to greater bending forces than tower legs. The structure-foot reinforcement apparatus 110 here has twelve-fold symmetry, having twelve reinforcement struts 114, each having a continuous flat base portion 118 which defines both the contact area 120 and the anchor portion 126. A dodecagonal strut connector 136 and flange-contact plate 140 are provided, and only one of each is illustrated. There is a plurality of secondary retaining members 150 positioned circumferentially around the foot 112 of the monopole and engaged therewith using fasteners 152. These secondary retaining members 150 centre the apparatus 110 relative to the monopole to increase rigidity and movement load to the monopole. This is shown in Figure 8; distances d1 and d2 on opposite sides of the foot are equal, due to this centring effect. Polygonal symmetry is provided for the structure-foot reinforcement apparatuses indicated; five-fold and twelve-fold symmetry, respectively. It will be appreciated that any polygonal arrangement could be provided, depending on the size of the structure to be reinforced. Indeed, a circular arrangement is entirely feasible. It is therefore possible to provide an apparatus which can be installed in a simple manner around the foot of a structure which requires strengthening or repair due to damage, corrosion, or similar. The reinforcement struts bypass the original anchors of the foot, whilst spreading the load thereacross using the strut connector. The words ‘comprises / comprising’ and the words ‘having / including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps, or components, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in 5 any suitable sub-combination. The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A structure-foot reinforcement apparatus comprising:a plurality of reinforcement struts, each of the reinforcement struts comprising a base portion having a contact area configured to in-use directly or indirectly contact a flange of a foot of a structure to be reinforced, an upper portion spaced apart from the base portion in an in-use vertical direction, and an anchor portion spaced from the contact area in an in-use horizontal direction and which permits connection of the reinforcement strut to a structure foundation; anda strut connector engagable with the upper portions of the plurality of reinforcement struts in-use to interconnect the plurality of reinforcement struts, the strut connector having a multi-part body to be receivable around the foot of the structure to be reinforced.

2. A structure-foot reinforcement apparatus as claimed in claim 1, wherein the strut connector forms an annulus when assembled.

3. A structure-foot reinforcement apparatus as claimed in claim 2, wherein a plurality of said strut connectors is provided, wherein joins of the multi-part bodies of the plurality of strut connectors are offset to one another.

4. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, further comprising a flange-contact plate configured to directly contact the flange of the foot of the structure to be reinforced in-use, the contact areas of the plurality of reinforcement struts being engagable with the flange-contact plate.

5. A structure-foot reinforcement apparatus as claimed in claim 4, wherein the flange-contact plate has a multi-part body to be receivable around the foot of the structure to be reinforced.

6. A structure-foot reinforcement apparatus as claimed in any one of claims 4 to 5, wherein the flange-contact plate forms an annulus when assembled.

7. A structure-foot reinforcement apparatus as claimed in any one of claims 3 to 6, wherein a plurality of said flange-contact plates is provided, wherein joins of the multi-part bodies of the plurality of flange-contact plates are offset to one another.

8. A structure-foot reinforcement apparatus as claimed in any one of claims 3 to 7, wherein the flange-contact plate comprises at least one flange-anchor connector for engagement with an existing anchor of the foot of the structure to be reinforced.

9. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, wherein each of the plurality of reinforcement struts comprises a flat base portion having the anchor portion thereon.

10. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, wherein the anchor portion comprises at least one fastener receiver aperture.

11. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, wherein the upper portion comprises at least one fastener receiver.

12. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, wherein each of the plurality of reinforcement struts comprises a vertical reinforcement member.

13. A structure-foot reinforcement apparatus as claimed in claim 12, wherein the vertical reinforcement member is or is substantially triangular.

14. A structure-foot reinforcement apparatus as claimed in claim 12 or claim 13, wherein two said vertical reinforcement members are provided either side of the base portion.

15. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, wherein the strut connector has a polygonal symmetry equal to a number of reinforcement struts provided.

16. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, wherein the upper portion comprises a clamping plate.

17. A structure-foot reinforcement apparatus as claimed in any one of the preceding claims, further including an earthing lug.

18. A method of reinforcing a damaged or weakened foot of a structure having a base flange, the method comprising the steps of:a] positioning a plurality of reinforcement struts around the foot of the structure such that a contact area of a base portion of each reinforcement strut directly or indirectly contacts the flange;b] positioning a strut connector having a multi-part body around the foot of the structure so as to contact an upper portion of each of the plurality of reinforcement struts;c] securing the strut connector with each of the plurality of reinforcement struts so as to interconnect the plurality of reinforcement struts; andd] at an anchor portion of each of the plurality of reinforcement struts which is spaced from the contact area in an in-use radial direction, securing the plurality of reinforcement struts to a structure foundation.

19. A method as claimed in claim 18, further comprising a step prior to step a] of contacting a flange-contact plate with the flange of the foot of the structure to be reinforced, the contact areas of the plurality of reinforcement struts being engagable with the flange-contact plate.

20. A method as claimed in claim 18 or claim 19, wherein the plurality of reinforcement struts is uniformly spaced around the foot of the structure to be reinforced.

21. A method as claimed in any one of claims 18 to 20, further comprising a step subsequent to steps b], c], and d] of grouting around the foot of the structure.14

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