GB2568537A

GB2568537A - Support for a structure

Info

Publication number: GB2568537A
Application number: GB1719242.8A
Authority: GB
Inventors: Ahmed Abubaker Kiari Mohamed
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-11-20
Filing date: 2017-11-20
Publication date: 2019-05-22
Anticipated expiration: 2037-11-20
Also published as: GB2568537B; GB201719242D0

Abstract

An assembly of a support (10) and an anchor arrangement (14A) for reinforcing a structure (12), comprises a first portion (10A), a second portion (10B) and at least a first connecting portion (10C) connecting the first and second portions (10A,10B) at a first end (10E) of the support (10). The first connecting portion (10C) is integral with the first and second portions (10A,10B). The first and second portions (10A,10B) and the first connecting portion (10C) are formed of fibres and a polymer. The anchor arrangement (14A) is configured to fix the first connecting portion (10C) to the structure (12) at a surface (13) such that the support (10) provides reinforcement for the structure (12). In an embodiment the support is a loop comprising straight first and second portions and two curved connecting portions, and is received in a channel in the structure.

Description

Support for a Structure

Field

A support and method for reinforcing a structure.

Background

Composite materials are used in a vast array of applications. In structural applications, for example, fibre reinforced polymer (FRP) composite materials can be used in the reinforcement of structures (e.g. made from concrete), including as an internal reinforcement for new structures and/or externally to strengthen existing structures.

As with any composite, the constituent materials are combined to achieve properties superior to individual components alone. FRP is a composite of two main components: high strength fibres (commonly carbon or glass), and a polymer. The polymer is called a resin in its wet state and the matrix after hardening. Fibres have high strength and provide the tensile capacity and stiffness of the composites. The polymer matrix on the other hand, provides load sharing between individual fibres through shear stress developed at the interface with the fibres. The polymer matrix can itself also be used as an adhesive to adhere the FRP composite to structural elements that are intended to be strengthened.

In strengthening applications FRP reinforcement is generally used in two forms. In the first form, FRP reinforcements (such as strips or sheets) are fixed to a structural element by a polymer adhesive, such as epoxy. In the second form, FRP bars are placed in shallow channels cut or otherwise formed into the structure, the bars fixed in place by a polymer or cementitious adhesive.

While conventional arrangements provide an effective reinforcement in many instances, there are drawbacks. For example, conventional arrangements are vulnerable to loss of integrity in the event of fire.

Summary

According to a first aspect, there is provided an assembly of a support and an anchor arrangement for reinforcing a structure, the support comprising:

a first portion;

a second portion;

at least a first connecting portion connecting the first and second portions at a first end of the support, wherein the first connecting portion is integral with the first and second portions, the first and second portions and the first connecting portion are formed of fibres and a polymer, the anchor arrangement being configured to fix the first connecting portion to the structure at a surface such that the support provides reinforcement for the structure.

The first connecting portion being fixed to the surface by the anchor arrangement means that interaction with the structure at elevated temperatures can still be provided through bearing at the first connecting portion. This means that the support can maintain its reinforcement or strengthening of the structure at elevated temperatures.

At a surface may be considered to be on the surface or in a channel in the surface of the structure.

The first connecting portion may be curved. The support may be a loop, e.g. the first and second portions extend longitudinally. The fibres may be carbon or glass. The support may comprise a continuous fibre filament.

This has an advantage of increased load sharing between fibres and increased strength.

The assembly may be configured to fix the first connecting portion to the structure after a temporary support has reduced deflection of the structure.

This has an advantage of maintaining the reduction in deflection of the structure.

The anchor arrangement may be configured to be biased by a biasing mechanism to cause tension in the support.

This has an advantage of reducing deflection in the structure and reducing existing cracks openings.

The anchor arrangement may comprise a first anchor for mechanically fixing the first connecting portion to the structure.

This has an advantage of providing a strengthening support with higher fire endurance.

The first anchor may comprise the biasing mechanism. The biasing mechanism may be a pulling or pushing mechanism.

This has an advantage that the fixing to the structure and the provision of the tensioning can be performed with a single component.

The anchor arrangement may comprise adhesive for fixing the first connecting portion and/or the first portion and/or the second portion to the structure. The adhesive may comprise a polymer adhesive or cementitious adhesive.

This has an advantage of providing increased adhesion of the support to the structure.

The assembly may comprise the structure.

The anchor arrangement may comprise a channel in the surface of the structure. At least part of the first connecting portion may be configured to be inserted in the channel in the surface of the structure. That is, the support may be configured to be near surface mounted (NSM).

This has an advantage that an existing structure can provide the anchor arrangement.

The first anchor may be located in the channel.

This has an advantage that the fixing to the structure and/or the provision of the tensioning can be performed in combination with the channel of the structure.

The support may have a second connecting portion connecting the first portion and the second portion at a second end of the support. The second connecting portion may be integral with the first and second portions. The assembly may comprise a second anchor arrangement. The second anchor arrangement may be configured to fix the second connecting portion to the structure at the surface.

This has an advantage that interaction with the structure at elevated temperatures can still be provided through bearing at the second connecting portion which provides increased strength or reinforcement at elevated temperatures.

The second anchor arrangement may be configured to be biased away from the anchor arrangement to cause tension in the support.

The second anchor arrangement may comprise a second anchor for mechanically fixing the second connecting portion to the structure.

According to a second aspect of the present disclosure there is provided a method of using an assembly according to the first aspect comprising:

fixing the first connecting portion to the structure at the surface of the structure using the anchor arrangement such that the support provides reinforcement for the structure.

This has an advantage that the reinforcement or strength provided by the support can be maintained at elevated temperatures by interaction between the support and the structure through bearing at the first connecting portion.

The method may comprise reducing deflection of the structure using a temporary support, fixing the first connecting portion to the structure using the anchor arrangement, and then removing the temporary support.

The method may comprise biasing the anchor arrangement using a biasing mechanism to cause tension in the support.

The method may comprise mechanically fixing the first connecting portion to the structure using a first anchor.

The first anchor may comprise the biasing mechanism.

The method may comprise fixing the first connecting portion to the structure using adhesive.

The method may comprise inserting at least a part of the first connecting portion in a channel in the surface of the structure such that the channel fixes the first connecting portion at the surface.

The method may comprise inserting the first anchor in the channel.

The method may comprise inserting the biasing mechanism in the channel.

The support may have a second connecting portion connecting the first portion and the second portion at a second end of the support. The second connecting portion may be integral with the first and second portions. The assembly may comprise a second anchor arrangement. The method may comprise fixing the second connecting portion to the structure at the surface using the second anchor arrangement.

The method may comprise biasing the second anchor arrangement away from the anchor arrangement to cause tension in the support.

The method of fixing the second connecting portion to the structure may comprise mechanically fixing the second connecting portion to the structure using a second anchor.

It should be understood that the individual features and/or combinations of features defined above in accordance with any aspect of the present invention or below in relation to any specific embodiment of the invention may be utilised, either separately and individually, alone or in combination with any other defined feature, in any other aspect or embodiment of the invention.

Brief Description of the Figures

These and other aspects will now be described with reference to the accompanying drawings.

Figure 1 shows a perspective view of a support fixed to a structure at a surface of the structure.

Figure 2A shows a perspective view of a mould for forming a support.

Figure 2B shows an exploded perspective view of the mould for forming a support.

Figure 3 shows a perspective view of a support fixed to a structure in a channel in a surface of the structure.

Figure 4A shows a side view of traditional FRP strips fixed to a structure at ambient temperature.

Figure 4B shows a bottom view of traditional FRP strips fixed to a structure at ambient temperature.

Figure 5A shows a side view of the support fixed to a structure at ambient temperature.

Figure 5B shows a bottom view of the support fixed to a structure at ambient temperature.

Figure 6A shows a side view of traditional FRP strips fixed to a structure at an elevated temperature.

Figure 6B shows a bottom view of traditional FRP strips fixed to a structure at elevated temperature.

Figure 7A shows a side view of the support fixed to a structure at elevated temperature.

Figure 7B shows a bottom view of the support fixed to a structure at elevated temperature.

Figure 8A shows a side view of the support fixed to a structure at a surface of the structure with the active system before the active system is used.

Figure 8B shows a side view of the support fixed to a structure at a surface of the structure with the active system in use.

Figure 9A shows a side view of the support fixed to a structure in a channel in the surface of the structure with the active system including a biasing mechanism.

Figure 9B shows a bottom view of the support fixed to a structure in a channel in the surface of the structure with the active system including a pushing mechanism.

Figure 9C shows a bottom view of the pushing mechanism.

Detailed Description

Figure 1 shows a support 10 fixed to a structure 12. The support 10 is fixed to a surface 13 of the structure 12 by an anchor arrangement including a first anchor 14A and a second anchor 14B. The support 10 shown in Figure 1 is made of Fibre Reinforced Polymer (FRP). The structure 12 is made from concrete. In other examples, the structure may be made from other materials, such as steel, timber, stone and masonry.

The support 10 is fixed at the surface 13 of the structure 12, or more specifically, to the surface 13 of the structure 12 (c.f. strips of FRP reinforcement fixed to a structural element). In this example, the surface 13 of the structure 12 extends horizontally with respect to the ground with the support 10 orientated longitudinally in the horizontal direction. That is, the surface 13 is the lowest most surface of the structure 12 and faces the ground. In the rest of the description we will use this convention but, in other examples, the support may be orientated in a different direction.

The support 10 is in a loop shape and has a first portion 10A and a second portion 10B which form the longitudinally extending sections of the loop. The support 10 has a first connecting portion 10C which connects the first portion 10A and the second portion 10B together at a first end 10E of the support 10. The support 10 has a second connecting portion 10D which connects the first portion 10A and the second portion 10B together at a second end 10F of the support 10. That is, the first and second connecting portions 10C, 10D form opposing end sections of the loop.

The first and second connecting portions 10C, 10D are both curved and are substantially the same shape and size. In other examples, the first and second connecting portions may be a different size and shape, e.g. forming a curve with a smaller or larger radius. In other examples, the support may be a different shape, e.g. the first portion and the second portion of the support may be smaller in length or the support may form a circular shape. The loop shape is an important feature and the loop doesn’t need to have a relatively long length compared to its width. In other examples, the support may have only a single connecting portion, e.g. the support having only the first connecting portion at the first end of the support, the first and second portions of the support extending away from the first end and not being connected together at the second end of the support. Although the support may have a single connecting portion, which provides advantages in the performance of the support that will become apparent, the rest of the description is restricted to the preferred example of the support having two connecting portions.

Having the first and second connecting portions 10C, 10D connecting the first and second portions 10A, 10B means that the support 10 is closed at each end 10E, 10F. The first connecting portion 10C is integral with both the first and second portions 10A, 10B. The second connecting portion 10D is integral with both the first and second portions 10A, 10B. This is achieved by forming the support 10 from at least one continuous fibre filament which is mixed with resin to form the polymer. It is preferred that the support is made from a single continuous fibre filament but in other examples a plurality of continuous fibre filaments could be used.

The first and second anchors 14A, 14B include bolts which attach to the surface 13 of the structure 12. The anchor 14A has a perpendicularly extending stop 15A which is curved to match the shape of the first connecting portion 10C. That is, the stop 15A extends downwards towards the ground in use. In use, the connecting portion 10C is located around the curved stop 15A and the curved stop 15A prevents movement in the horizontal direction from the first end 10E towards the second end 10F. The stop 15A also has three protrusions 15C which prevent the support 10 from falling towards the ground when in position. The anchor 14B has a corresponding stop 15B and corresponding protrusions 15D. In other examples, the anchors may be of another form as long as they act to restrict movement of the connecting portions.

An example method of forming the integral support 10 will now be described with reference to Figures 2A and 2B. The support 10 is formed using a continuous fibre tow to form the closed loop. The support 10 of FRP is produced by winding fibres around a mould 16 shown in Figure 2A. The mould 16 is rotated around the lateral axis X (shown in dotted line in figure 2A) and functions as a mandrel.

The mould 16 has four grooves 18 which extend around the longitudinal circumference of the mould 16. The support 10 is made by winding a continuous fibre filament within one of the grooves 18 in the mould 16. For example, a single continuous filament mixed with resin may be wound around the mould 25 times to make the support 10. As another example, a single filament may be wound 12 times, then cut, and the winding then carried on to reach 25 times. As long as the continuous filaments are wound enough times then the support 10 will work as intended. In other examples, the mould can have more or less grooves. The shape of the groove 18 controls the cross sectional shape of the produced support 10.

Polymer resin is applied between the layers of fibres tows, e.g. by using a brush. The mould 16 is rotated around the axis X and the fibres are wound around the mould 16 until the support 10 is at the desired size.

Once the fibre winding process around the mould 16 is completed, the supports 10 are left in the mould 16 to cure. After hardening, the polymer resin becomes the polymer matrix. Up to four supports 10 can be made in the mould 16, one for each groove 18. After the supports 10 have cured, the mould 16 is disassembled by removing nuts 20A and bolts 20B as shown in Figure 2B. Once the mould is disassembled, the hardened supports 10 can then be removed.

Straight FRP bars are not suitable for bending into a loop shape as this causes high strains and damages the reinforcement bars. Also, it is not possible to join the two ends of a FRP bar to form a closed loop without relying upon polymer matrix at the connection, which is likely to fail under elevated temperatures.

Referring to Figure 3, the support 10 is shown fixed to a structure 21. The support 10 is the same as the support 10 shown in Figure 1. The structure 21 is similar to the structure 12 shown in Figure 1 but, in this example, the structure 21 has a channel 22 cut into a surface 23 of the structure 21. The channel 22 has a shape corresponding to the support 10 which allows the support 10 to be inserted into the structure 21. That is, the channel 22 is a loop shape which is cut to a depth in the surface 23 of the structure 21 such that the support 10 can be inserted below the surface 23 of the structure 21.

The support 10 is fixed at the surface 23 of the structure 21, or more specifically, fixed in the channel 22 in the surface 23 of the structure 21 (c.f. bars of FRP reinforcement fixed to a surface of a structure). At a surface 23 includes being in a channel 22 in the surface 23 of the structure 21. In this configuration, the support 10 is considered to be near the surface 23 of the structure 21. This method of cutting a channel in the surface and inserting the reinforcement is called Near Surface Mounted (NSM). As long as the support 10 is inserted into a channel 22 in the surface 23 of the structure 21, then it can be considered to be in the channel 22 in the surface 23 of the structure 21, i.e. at the surface 23. The support 10 does not need to be flush with the surface 23. Preferably, the support 10 is inserted in a relatively shallow channel 22 but could be positioned in deeper channels as required.

In a similar way that the stop 15A shown in Figure 1 prevents movement of the first connecting portion 10C in the horizontal direction from the first end 10E towards the second end 10F of the support 10, the inner wall of the channel 22 prevents horizontal movement of the first connecting portion 10C of the support 10. That is, the channel 22 wall of the curved section which has the smaller radius (the inner wall), corresponding to the first connecting portion 10C, holds the first connecting portion 10C from being pulled in the horizontal direction towards the second connection portion 10D. The inner wall, corresponding to the second connecting portion 10D, does likewise for the second connecting portion 10D.

The channel 22 effectively provides an anchor at the first and second ends 10E, 10F of the support 10 to fix the support 10 to the structure 21. Thus, the channel 22 is an anchor arrangement. In addition to this anchor, adhesive (polymer or cementitious adhesive) can be added to bond all or part of the support to the structure 21. For example, the adhesive can be added to the part of the support 10 not held by the anchor (e.g. the first and second portions 10A, 10B of the support 10) or to the anchor zone (e.g. the first and second connecting portions 10C, 10D).

As mentioned above, previously FRP reinforcement for existing structures have been in the form of straight strips or straight bars. Figure 4A shows a side view of straight strips 24 affixed to a structure 26 at ambient temperature and Figure 4B shows a bottom view. In this example, the strips 24 are shown on the surface 28 of the structure 26 but this is not important as they could equally be located in a channel cut into the surface. Further, it is not relevant that it is the strips that are shown here as the discussion is equally applicable to bars.

The strips 24 are fixed to the structure 26 with adhesive, the adhesive being located along the full length of the strips 24. The adhesive is polymer adhesive or cementitious adhesive. The structure 26 is at ambient temperature and is subjected to a four point bending test at the points and direction shown with arrows P.

During the test, the forces applied act to cause a deflection in the structure 26, i.e. the central portion of the structure 26 is pushed downwards towards the ground. In practice, this will be a structure under loads, such as the weight from people, cars, furniture, or the structure itself etc. Horizontally extending arrows 30 show the interfacial forces which the strips 24 are subjected to during the test as the strips 24 take the strain from the forces which act to cause a deflection in the structure 26. The interfacial forces act horizontally outwards from the centre of the strips 24 towards the ends of the strips 24.

As can be seen from Figure 4A, at ambient temperature, the adhesive is capable of transferring the load from the structure 26 to the strips 24 and there is a reduced deflection caused in the structure 26. That is, the surface 28 of the structure 26 is still relatively straight. In practice, even new structures will have some deflection. Figures

4A-7B illustrate the difference in deflection that occurs using the support 10 when compared to traditional methods.

Figure 5A shows a side view of the support 10 affixed to the structure 12 at ambient temperature and Figure 5B shows a bottom view. The first and second anchors 14A, 14B which mechanically fix the support 10 to the structure 12 are shown at the first and second ends 10E, 10F of the support 10. Horizontally extending arrows 32 show the interfacial forces which indicate force transfer between the structure 12 and the support 10 under loading. Additional force transfer between structure 12 and the support 10 occur at the first and second ends 10E, 10F, of the support 10 in the form of bearing forces, shown by arrows 34, due to the connecting portions 10C, 10D being held by, and exerting a force on, the anchors 14A, 14B.

In addition to the anchors 14A, 14B fixing the support 10 to the structure 12, the support 10 is also fixed to the structure 12 with adhesive, the adhesive being located on the first and second portions 10A, 10B of the support 10.

As can be seen from Figure 5A, at ambient temperature, the anchors 14A, 14B and the adhesive are capable of transferring the load between the structure 12 and the support 10 and there is reduced deflection caused in the structure 12. That is, the surface 13 of the structure 12 is still relatively straight. In other examples, the adhesive could be located on all of the support 10, including at the first and second connecting portions 10C, 10D. In other examples, the support 10 may be used without adhesive on the support 10. That is, the support 10 is only fixed to the structure 21 through the first and second anchors 14A, 14B at the first and second ends 10E, 10F.

Turning now to Figures 6A (side view) and 6B (bottom view), the structure 26 and the strips 24 are shown being subjected to heat H at a horizontally central position from below the surface 28 of the structure 26. That is, the structure 26 and the strips 24 are subjected to an elevated temperature above the ambient temperature of the example shown in Figures 4A and 4B.

Interfacial forces are still acting on the strips 24 but, as illustrated by the smaller size of the arrows 36, the forces are reduced along the length of the strips 24. This is because, under heating, the polymer matrix (whether as a component in the FRP strips or as the adhesive holding the strips 24 to the structure 26) softens. This causes bond degrading between the strips 24 and the structure 26 which, in turn, causes failure of the strengthening mechanism. Softening of a polymer matrix typically occurs at temperatures in range of 100 - 200 °C.

In a central portion of the structure 26, the bond between the strips 24 and the surface 28 of the structure 26 has been lost, as illustrated by the absence of arrows 30 indicating no interfacial forces present. This means that the strips 24 cannot help support the weight on the structure 26 from the downward pressure P caused by the four point bending test. Thus, a relatively large deflection occurs in the structure 26. Furthermore, relatively large cracks 38 appear in the surface 28 of the structure 26 which are undesirable. In practice, this will be a structure under loads, such as the weight from people, cars, furniture, or the structure itself etc.

Referring now to Figures 7 A (side view) and 7B (bottom view), the structure 12 and the support 10 are similarly shown being subjected to heat H at a horizontally central position from below the surface 13 of the structure 12. That is, the structure 12 and the support 10 are subjected to an elevated temperature above the ambient temperature of the example in Figures 5A and 5B.

In the example shown in Figures 7A and 7B, the surface bond degrades between the support 10 and the structure 12 along the first and second portions 10A, 10B of the support 10. That is, the interfacial forces due to the load transfer through the adhesive are removed in the central portion and reduced along the length of the support 10. This is illustrated by the smaller arrows 40 and the absence of the arrows 40 in the central portion. However, the interaction between the support 10 and the structure 12 is still provided through bearing at the first and second ends 10E, 10F of the support 10. That is, the connecting portions 10C, 10D being attached to the structure 12 through the anchors 14A, 14B provides increased bearing forces which strengthen the structure 12. This is illustrated by the larger arrows 42 acting at the first and second ends 10E, 10F.

Although a deflection occurs in the structure 12, this is less than occurs with the strips 24 of Figures 6A and 6B. This means that only relatively small cracks 44 appear in the surface 13 of the structure 12 when compared with the cracks 38 in the structure 26 of Figures 6A and 6B.

The polymer matrix softening of FRP strips under elevated temperature causes bond degradation between FRP strips and a structure which causes slipping of the strips with respect to the structure and leads to failure. Widespread use of FRP reinforcement for strengthening structures has been being hindered due to their relatively weak performance at elevated temperatures, such as in the event of fire. The first and second connecting portions 10C, 10D being fixed to the structure 12 provides reinforcement for the structure 12 even at elevated temperatures. Thus, they at least partially overcome the sensitivity of FRP reinforcement to elevated temperatures.

Both the two traditional methods of using FRP in structural strengthening applications have performance issues when subjected to elevated temperatures. Both of these systems, FRP strips fixed to outer surface of structure using adhesive 3 and FRP bars inserted into grooves in structure filled with adhesive, are very sensitive to elevated temperatures because the strengthening mechanism integrity is hinged on polymer matrix and adhesive.

The usage of the support 10 having the connecting portions 10C, 10D provides an addition interaction mechanism between the FRP reinforcement and the structure 12. When the surface bond degrades at elevated temperatures, interaction with the structure 12 is still provided through bearing at the first and second ends 10E, 10F of the support 10. This will reduce the structure deflection, reduce size of cracks opening and increase the structure stiffness under loads. That is, the performance of the reinforcing support is improved when compared with straight strips or bars.

Although the above examples describe anchors for fixing the connecting portions at the ends of the support to the structure, in other examples, other fixing means could be used. For example, adhesive could be used to fix the connecting potions to the structure and could still produce an increase in performance as bearing at the ends of the support would be provided. This can lead to increased strengthening as the connecting portions are held to the structure at their ends, especially when the source of the increase in temperature is a substantial distance away from the first and second ends of the support.

Although the examples shown in Figures 5A, 5B, 7A and 7B have the support 10 fixed at the surface 13 of the structure 12, the same benefits are also found when using the support 10 fixed in the channel in the surface of the structure. For example, as shown in Figure 3, when the support 10 has been inserted into a channel 22 in the surface 23 of the structure 21 and fixed to the structure 21.

The support 10 described above in relation to Figures 1, 3, 5A, 5B, 7A and 7B are a passive system. In the passive technique, the support 10 is fixed to the surface 13 of the structure 12 and fastened at the first and second ends 10E, 10F of the support 10 with anchors 14A, 14B. In the passive configuration, the support 10 will only engage if more forces are applied on the structure (e.g. as in the four point bending test). However, the support 10 can also be used in a different configuration such as an active system.

One way that an active system can be achieved is by pushing apart (or pulling toward the outside) the anchors which cause tension forces in the support 10. That is, the first anchor is biased to cause tension in the support. This pre-stressing may be achieved in the flowing way: First, the anchor 14A at the first end 10E of the support 10 is fixed to the structure 12 while the other anchor 14B is kept unfixed. A hydraulic jack is then clamped to the structure 12 near the un-fixed anchor 14B. The jack is then used to stretch the anchor 14B at the un-fixed end (this creates tension stresses in the support 10). This anchor 14B is then fixed to the structure 12 (e.g. by bolts). The pressure from the hydraulic jack can be released and the jack is removed. The support 10 is then pre-stressed before being put into use.

Figure 8A shows a structure 46 with a deflection and three cracks 48. The support 10 is fixed to surface 50 of the structure 46 with anchors 14A, 14B at the first end second ends 10E, 10F of the support 10. However, since the support 10 was affixed to the structure 46 after deflection occurred then the support 10 is not able to reduce the structure 46 deflection. The support 10 will only engage if more deflection of the structure occurs.

Figure 8B shows the active system in action. Forces have been applied to the anchors 14A, 14B in an outwards direction (see arrows 52) to increase the stiffness of the structure 46. This is possible because the support 10 is anchored to the structure 46 through the anchors 14A, 14B. As shown in Figure 8B, this in turn reduces the deflection of the structure 46 and the size of the cracks 48 under loading.

Another way the active system is achieved is by using a temporary adjustable support (not shown) to reduce the deflection of the structure 46. One end of the temporary support is located on a rigid structure, such as a strong ground, while the other end is placed into contact with the surface 50 of the structure 46. The temporary support is then adjusted to move it in an upwards direction to reduce the deflection. The support 10 is then fixed onto the structure 46 to take the load and the temporary support is removed. In this way, the stiffness of the structure 46 can be increased and the size of the cracks can be reduced. In other examples, the two active system methods described above can be combined to produce even further improved performance of the support 10.

Although the examples have described the structure deformation as downward deflection, this may not always be the case. In other examples, deformation (e.g. deflection) may occur in different directions, such as upwards and sideways. The support 10 can also be used to reduce or prevent deflections in all directions.

The active system can also be used with the support 10 in the Near Surface Mounted (NSM) configuration. The support 10 in NSM is shown in passive configuration in Figure 3 with the support 10 located in the channel 22 in a surface 23 of the structure 21. In this passive configuration, the support 10 will only engage if further loading is applied on the structure 21.

Figure 9A shows the support 10 with an active system. The support 10 is inserted into a channel 54 in a surface 56 of a structure 58. The channel 54 at both the first and second ends 10E, 10F of the support 10 is wider than the channel 22 of the structure 21 shown in Figure 3. This is so a biasing mechanism 60 can be inserted into the channel 54 between the inner wall of the channel 54 and the support 10. In this example, the biasing mechanism 60 is an anchor for mechanically fixing the first connecting portion 10C to the structure 58. That is, the biasing mechanism 60, in combination with the channel 54, is an anchor arrangement. In other examples, there may be a wider channel at one end of the support only such that there is only one biasing mechanism. The other end of the support may just be located in the (normal sized) channel and supported by the structure.

In other examples, an anchor can be inserted into the channel 22 to provide the anchor arrangement without the associated biasing. That is, the anchor in the channel 22 is similar to the first and second anchors 14A, 14B except that it is located in the channel 22 rather than on the surface of the structure.

When the biasing mechanism 60 is activated, it puts the support 10 under tension forces. This introduces forces in the structure 58 that can reduce the structure 60 deflection and reduce the existing cracks openings. The active system of the NSM support 10 can be used with or without polymer adhesive/cementitious grout. If adhesive/grout is used this means the interaction between the support 10 and the structure 58 relies on the anchor (i.e. the inner walls of the channel 54 and the biasing mechanism 60) at the first and second ends 10E, 10F of the support 10 and adhesive/grout bond along the length of the support 10. In this case, tension forces on the support 10 should be applied before the hardening of the adhesive/grout. Adjustable temporary supports can also be used with NSM to reduction deflection of the structure 58 before installing the support 10 into the channel 54.

The biasing mechanism 60 for the support 10 can take different forms as long it provides an anchor for the support 10 and can also can be pushed or pulled to introduce stress in the support 10 in the active configuration.

A corresponding biasing mechanism 61 is also located in the channel 54 at the second end 10F of the support and works in the same way. Thus, the corresponding biasing mechanism 61 is likewise an anchor arrangement. In some, examples the biasing mechanism 60 and corresponding biasing mechanism 61 work in combination with each other to increase the tension and in other examples, one or other of the biasing mechanisms 60, 61 work independently. In other examples, there may be a biasing mechanism at one end of the support only. The other end of the support may just be located in the channel and supported by the structure.

Figure 9B shows an example pushing mechanism 62 that has been inserted into the channel 54. The pushing mechanism 62 comprises a first part 64 shaped to correspond to the straight inner wall of the wider channel 54 and a second part 66 shaped to correspond to the first connecting part 10C.

Figure 9C shows the pushing mechanism 62 with a hydraulic jack 68 which can be used to push apart the first and second parts 64, 66 which are connected by threaded screws 70. Once the first and second parts 64, 66 have been separated by the desired distance, nuts 72 are tightened on the screws 70 to hold the first and second parts 62, 64 of the pushing mechanism 62 in position. The hydraulic jack 68 can then be released and removed. In other examples, a pulling mechanism could be used instead.

In use, the support 10 is fixed to the structure using one of the methods described above. For example, the support 10 may be fixed mechanically or by adhesive to the structure at a surface of the structure, i.e. on the surface or in a channel in the surface of the structure. Further, the support 10 may be fixed to the structure before or after a deflection has occurred in the structure. The support 10 may be used in a passive and/or active configuration. Thus, the support 10 can provide reinforcement to existing structures with the connecting portions 10C, 10D being fixed at the surface of the structures. The support 10 can be retro-fitted to existing structures, concrete or otherwise. There is great scope for using the supports 10 in place of traditional FRP bars or strips as they are less susceptible to elevated temperatures and provide stiffness and strengthening at higher temperatures for longer periods than the traditional FRP bars or strips.

Claims

1. An assembly of a support and an anchor arrangement for reinforcing a structure, the support comprising:

a first portion;

a second portion;

2. The assembly according to claim 1, wherein the first connecting portion is curved.

3. The assembly according to any preceding claim, wherein the support comprises a continuous fibre filament.

4. The assembly according to any preceding claim, wherein the assembly is configured to fix the first connecting portion to the structure after a temporary support has reduced deflection of the structure.

5. The assembly according to any preceding claim, wherein the anchor arrangement is configured to be biased by a biasing mechanism to cause tension in the support.

6. The assembly according to any preceding claim, wherein the anchor arrangement comprises a first anchor for mechanically fixing the first connecting portion to the structure.

7. The assembly according to claim 6 when dependent on claim 5, wherein the first anchor comprises the biasing mechanism.

8. The assembly according to any preceding claim, wherein the anchor arrangement comprises adhesive for fixing the first connecting portion and/or the first portion and/or the second portion to the structure.

9. The assembly according to any preceding claim, wherein the assembly comprises the structure.

10. The assembly according to claim 9, wherein the anchor arrangement comprises a channel in the surface of the structure and wherein at least part of the first connecting portion is configured to be inserted in the channel in the surface of the structure.

11. The assembly according to claim 10 when dependent on claim 6, wherein the first anchor is located in the channel.

12. The assembly according to any preceding claim, the assembly comprising a second anchor arrangement, the support comprising a second connecting portion connecting the first portion and the second portion at a second end of the support, the second connecting portion is integral with the first and second portions, and the second anchor arrangement is configured to fix the second connecting portion to the structure at the surface.

13. The assembly according to claim 12, wherein the second anchor arrangement is configured to be biased away from the anchor arrangement to cause tension in the support.

14. The assembly according to either or claims 12 or 13, wherein the second anchor arrangement comprises a second anchor for mechanically fixing the second connecting portion to the structure.

15. A method of using an assembly according to any of claims 1 to 14 comprising: fixing the first connecting portion to the structure at the surface of the structure using the anchor arrangement such that the support provides reinforcement for the structure.

16. The method according to claim 15, further comprising reducing deflection of the structure using a temporary support, fixing the first connecting portion to the structure using the anchor arrangement, and then removing the temporary support.

17. The method according to either or claims 15 or 16, further comprising biasing the anchor arrangement using a biasing mechanism to cause tension in the support.

18. The method according to claims 15 to 17, further comprising mechanically fixing the first connecting portion to the structure using a first anchor.

19. The method according to claim 18 when dependent on claim 17, wherein the first anchor comprises the biasing mechanism.

20. The method according to claims 15 to 19, further comprising fixing the first connecting portion to the structure using adhesive.

21. The method according to claims 15 to 20, further comprising inserting at least a part of the first connecting portion in a channel in the surface of the structure such that the channel fixes the first connecting portion at the surface.

22. The method according to claim 21 when dependent on claim 18, further comprising inserting the first anchor in the channel.

23. The method according to claim 21 when dependent on claim 17, further comprising inserting the biasing mechanism in the channel.

24. The method according to any of claims 15 to 23, the assembly comprising a second anchor arrangement, the support comprising a second connecting portion connecting the first portion and the second portion at a second end of the support, the second connecting portion is integral with the first and second portions, and the method comprising fixing the second connecting portion to the structure at 5 the surface using the second anchor arrangement.

25. The method according to claim 24, further comprising biasing the second anchor arrangement away from the anchor arrangement to cause tension in the support.

26. The method according to either or claims 24 or 25, further comprising mechanically fixing the second connecting portion to the structure using a second anchor.