Patent Application
20250052052
According to the invention, there is provided a structural assembly. More particularly, the invention is directed to a structural assembly that is of a Fibre Reinforced Polymer (FRP).
Reinforced concrete has the necessary structural integrity for fabrication of components for use in structural assemblies, such as retaining walls. An example of a retaining wall is one that includes posts and sleepers. The posts have opposed, outwardly facing channels. The posts are positioned, in equally spaced orientation relative to each other, along a line along which the retaining wall is to be erected. Opposed ends of the sleepers are slid into respective channels of consecutive posts to be retained, one on top of each other, between the posts. With adequate foundations, such retaining walls have been found to be effective.
Reinforced concrete has a significantly higher mass per cubic metre than other materials such as FRP and similar. Furthermore, structural components of reinforced concrete are required to be cast. This is usually carried out by positioning the reinforcing in a mould, pouring the concrete into the mould, and allowing the concrete to set. This is much slower than industrialised processes such as extrusion and pultrusion.
The weight of the concrete sleepers requires that they be manipulated into position by two or more workers and/or specialised lifting equipment. This can result in high cost resulting from the time required to erect the retaining wall and the need for compliance with safety protocols.
According to an aspect of the invention, there is provided a structural assembly which comprises:
The, or each, panel, and the posts, may be pultruded products.
The front wall and the upper and lower walls of the, or each, panel may be substantially planar.
The rear wall of the, or each, panel may be shaped to define two or more outwardly curved portions.
The rear wall of the, or each, panel may define at least one corrugation.
The upper and lower walls of the, or each, panel may be oriented substantially orthogonally with respect to the front wall.
The internal corners defined by the front and upper and lower walls of the, or each, panel may have a minimum radius of between 2 mm and 5 mm.
A height of the upper and lower walls of the, or each, panel may be between 0.6 and 0.8 times an overall thickness of the, or each, panel.
The FRP may include at least one of glass fibre yarn and glass fibre mat. The FRP may include both glass fibre yarn and glass fibre mat. The FRP may be between 50 percent and 60 percent, by mass, glass fibre yarn, and between 10 percent and 15 percent, by mass, glass fibre mat.
The web of each post may be hollow and may include two, spaced web walls. At least one bracing wall may interconnect the web walls.
An overall width of each post may be between 0.4 and 0.6 times an overall depth of the, or each, post.
One of the flanges may be between 0.7 and 0.9 times the width of the other flange.
Corners defined by the web and the flanges of each post may have a radius of between 10 mm and 14 mm.
According to an aspect of the invention, there is proved a panel for a structural assembly, the panel comprising:
According to an aspect of the invention, there is provided a post for a structural assembly, the post comprising:
According to an aspect of the invention, there is provided a method of erecting a structural assembly, the method comprising the steps of:
In
The panel 10 is hollow and, operatively, has a front wall 12, a rear wall 14, an upper wall 15, and a lower wall 16.
The panel 10 is a pultruded product of FRP. The FRP is between 50 percent and 60 percent, by mass, glass fibre yarn, and between 10 percent and 15 percent, by mass, glass fibre mat. The FRP can also contain between 25 percent and 30 percent resin, between 3 percent and 5 percent calcium carbonate powder, between 0.05 percent and 0.1 percent anti-UV powder, between 0.4 percent and 0.5 percent pigment paste, and between 0.3 percent and 0.5 percent curing agent. These amounts can be varied depending on the required size of the panel 10 and its application.
The front wall 12 and the upper and lower walls 15, 16 are substantially planar. The rear wall 14 is shaped to define three outwardly curved portions in the form of an intermediate portion 18.1 interposed between operatively upper and lower portions 18.2, 18.3. The upper and lower portions 18.2, 18.3, are connected to the upper and lower walls 15, 16 with generally planar sections 20, 22, respectively.
The panel 10 can have any desired length, depending on the application. That length can be achieved simply by cutting the pultruded product at appropriate lengths.
As can be seen in
Conventionally, concrete panels, referred to as “sleepers” are used with concrete or steel posts to form retaining walls. The posts define opposed channels so that opposed sides of the sleepers can be received in facing channels of consecutive posts. The concrete panels are solid. They also have a flat block shape, with generally planar faces. As such they are heavy. For example, a 2 m long concrete sleeper for a retaining wall can weigh between 70 kg and 80 kg. It follows that specialised equipment is required to raise and lower the sleepers into position. Alternatively, it is necessary for two or more operators to manipulate the sleepers. Furthermore, any manual handling of the sleepers must be done with care, to avoid injury. As a result, it can be expensive to work with the concrete sleepers due to the added labour and the need to adhere to safety protocols. Such sleepers rely on the inherent structural integrity of reinforced concrete. As such, minimal effort is required to conceive of a shape of the concrete that is best suited for retaining walls.
FRP does not have the inherent structural integrity of reinforced concrete. It follows that the structural integrity of an FRP component lies largely in the shape of that component. Structural integrity can be achieved by making use of the architectural principles associated with arch structures. As is known, an arch provides the material with which the arch is fabricated with a mechanical advantage in respect of a force exerted downwardly on the arch. In various applications, a horizontal arch is used to support a pressure, such as the hydrostatic pressure exerted on an arch dam wall. Arches are effective because they resolve forces into compressive stresses, eliminating tensile stresses. As a “height” of an arch decreases, the outward thrust increases. This outward thrust must be restrained, either with internal ties or external bracing, such as abutments.
In this embodiment, pressure of the retained substrate is exerted generally evenly over the rear wall 14, between the upper and lower walls 15, 16. To address this, the three outwardly curved portions 18.1, 18.2, and 18.3 define three arches that span an area between upper edges of respective planar sections 20, 22. The pressure of the retained substrate is resolved into compressive stresses in the portions 18.1, 18.2, and 18.3. It will be appreciated that a different number of curved portions may be suitable. That may depend on the height of the panel, or on other factors such as overall size of the panel and the wall thickness of the panel.
In profile, as can be seen in the drawings, the planar sections 20, 22 and the upper and lower walls 15, 16 define an included angle of greater than 90 degrees. This allows the planar sections 20, 22 to absorb compressive stresses set up by the pressure of the retained substrate. This may tend to drive the upper and lower walls 15, 16 apart. However, the orientation of the curved portions 18.2, 18.3, and the respective planar sections 20, 22 relative to the retained substrate results in the pressure of the retained substrate tending to drive the upper and lower walls 15, 16 towards each other, thus countering the action of the compressive stresses being set up in the planar sections 20, 22.
It is to be appreciated that, as with any arched structure, the compressive stresses are borne by a central region of the arched structure. In arched structures that are comprised of discrete blocks, a keystone would absorb these stresses. This keystone is often larger than the other blocks because of the need to absorb the stresses. In this embodiment, a central zone 24 is enlarged so that it can absorb the stresses without damage or a breakdown in the structural integrity of the rear wall 14.
Typically, the panel has a length of 2000 mm. In
In such embodiments, a thickness of the front wall 12 is between 2 mm and 3.5 mm, for example, 2.8 mm. A thickness of the upper and lower walls 15, 16 is between 2.5 mm and 4 mm, for example 3.2 mm. A thickness of the rear wall 14, excluding the central zone 24, is between 3 mm and 4 mm, for example, 3.5 mm. A thickness of the central zone 24 is between 6 mm and 7 mm, for example, 6.5 mm.
More generally, a height of the upper and lower walls 15, 16 of the panel 10 is between 0.6 and 0.8 times an overall thickness of the, or each, panel 10.
Given that FRP does not have the structural integrity of concrete, it is undesirable that excessive stress concentration be set up in the FRP. As is known, stress concentration set up at an intersection of two walls is a function of a radius of curvature at that intersection. In this case, stress concentrations are set up at corners 26.1, 26.2 defined by the front wall 12, and the upper and lower walls 15, 16, respectively. This is exacerbated by the fact that the front wall 12 is oriented at about 90 degrees to the upper and lower walls 15, 16. To mitigate potential damage caused by such stress concentration, the radii of curvature at the corners 26.1, 26.2 is a minimum of between 3 mm and 5 mm, for example 4 mm. Stress concentration is less of a factor at corners 28.1, 28.2 defined by the rear wall 14, and the upper and lower walls 15, 16, respectively. The radii of curvature at the corners 28.1, 28.2 is a minimum of between 1 mm and 3 mm, for example, 2 mm.
The weight of the panel in
In
The panel 60 is hollow and has a front wall 62, a rear wall 64, an upper wall 66, and a lower wall 68.
The panel 60 is also a pultruded product of the FRP described above.
The front wall 62 and the upper and lower walls 66, 68 are substantially planar. The rear wall 64 defines a single outwardly curved portion 70. The curved portion 70 has a number of channels or longitudinal recesses, for example, three channels 72 that extend along a length of the panel 60. The curved portion 70 provides the mechanical advantage of an arch, as described above. The channels 72 enhance a structural integrity of the curved portion 70.
In
The post 30 is a pultruded product of the FRP from which the panel is pultruded.
The post 30 can have any desired length. This can be achieved simply by cutting the pultruded product at appropriate lengths.
The post 30 includes a web 32 and two opposed flanges 34.1, 34.2, the web 32 being interposed between the flanges 34. The web 32 and the flanges 34.1, 34.2 define opposed channels 33, such that opposed sides of the panel 10, 60 can be received in facing channels 33 of consecutive posts 30.
The web 32 is hollow and includes two, spaced web walls 36. A bracing wall 38 interconnects the web walls 36 to enhance the structural integrity of the post 30.
As set out above, conventionally steel, or concrete posts are used with the conventional concrete sleepers described above to form retaining walls. For walls that are to be over 1 m in height it is generally necessary to use specialised equipment to manipulate the posts. Any manual handling must be done with care, to avoid injury. As with the sleepers, such posts rely on the inherent structural rigidity of reinforced concrete or steel. As such, minimal effort is required to conceive of a shape that is best suited for retaining walls. For example, in the case of steel, a conventional, standard I-beam can be used.
FRP does not have the structural integrity of steel. It follows that the post 30 is required to have a shape that imparts the requisite structural integrity to the post 30.
The hollow web 32 with the bracing wall 38 can impart a structural integrity that would be equivalent to a solid web of like dimensions. However, such a web would not lend itself to pultrusion. Furthermore, such a web would result in a post that may be too heavy to be handled by a single operator.
As with the panel 10, it is necessary to avoid excessive stress concentration in the FRP of the post 30. These could occur at outer corners 40 defined by the flanges 34.1, 34.2, and the walls 36. The radii of curvature at the corners 40 is between 10 mm and 15 mm, for example 12 mm. It has been found that this can serve to keep stress concentrations at an acceptable level while maintaining the characteristic of providing the channels 33 for a required number of the panels 10 to be received between the posts 30.
The walls 36 and the flanges 34.1, 34.2 define internal corners 42 within the web 32. Given their position, the corners 42 are not as prone to the build-up of stress The radii of curvature at the corners 42 are a minimum of between 4 mm and 6 mm, for example 5 mm.
The cross section of the post 30 as shown in
More generally, an overall width of each post 30 is between 0.4 and 0.6 times an overall depth of the, or each, post 30. Also, generally, the flange 34.1 is between 0.7 and 0.9 times the width of the flange 34.2. The post 30 can be positioned, in use, so that the larger flange 34.2 can enhance a structural integrity of one side of the post, where necessary and without utilising additional material on a side where the strength is not required. It will be appreciated that this flexibility is not possible with steel posts that are usually standard I-beams. The fact that the post 30 is pultruded facilitates the use of posts that do not necessarily have a standard cross-section or profile, allowing customisation to suit different environments.
In
In
The post 80 is a pultruded product of the FRP described above.
The post 80 can have any desired length. This can be achieved simply by cutting the product at appropriate lengths.
The post 80 includes a web 82 and two opposed flanges 84.1, 84.2, the web 82 being interposed between the flanges. The web 82 and the flanges 84.1, 84.2 define opposed channels 86 such that opposed sides of the panel 10, 60 can be received in facing channels 86 of consecutive posts 80.
The retaining wall assembly 100 includes at least two of the posts 30 mounted in a concrete pier 104, in a conventional manner. The posts 30 can be replaced with posts 50 or 80. A number of the sleepers 10 are positioned, one on top of another between the posts 30, with opposed sides of each sleeper 10 positioned in facing channels 33. As can be seen in
The posts and sleeper covered by the appended claims were tested individually, that is, outside of their intended application in a retaining wall. The posts were provided in three different depths (100 mm, 125 mm, and 175 mm). Panels, or sleepers, were provided in three different heights (190 mm, 200 mm, and 205 mm). These articles were subjected to a 4-point loading test. A number of the posts were tested by applying the loads to bottom flanges (the post horizontal) to simulate realistic site conditions, using specialised brackets. The tests were conducted using a hydraulic actuator and recording deflections using a laser sensor. The actuator was set up to apply displacement control loading at a rate of 1 mm/min.
The posts and the sleepers described above and covered by the appended claims were also tested in the intended application in a retaining wall assembly, such as the assembly 100 shown in
The tests were carried out up to a maximum allowable deflection of (span length)/120, which is an Australian official standard. In this case, the span was 1600 mm, providing a maximum deflection of 13.3 mm. The sleepers failed at a lower displacement magnitude so only maximum capacity was used to check the safety of the sleepers.
The safety of a retaining wall assembly can be assessed by calculating a ratio of the peak test load to the design load in terms of uniform distributed load (UDL). For the sleepers, this was calculated to be between 1.6 to 3.1, which is considered safe. For the posts, with depths of 125 mm and 175 mm, the calculated ratio was 1.0 to 1.34, which is considered safe.
It follows that a retaining assembly erected in a conventional manner using the sleepers and posts described herein can have the necessary structural integrity, without the need for concrete sleepers and concrete or steel posts. As set out above, the FRP of the sleepers and posts, together with their shapes or profiles allows those components to be suitable for use in applications previously performed by concrete products. Thus, a retaining wall with the sleepers and posts described herein can be erected faster, safer and at a lower cost than an equivalent retaining wall using concrete sleeper and concrete or steel posts.
The appended claims are to be considered as incorporated into the above description.
Throughout this specification, reference to any advantages, promises, objects or the like should not be regarded as cumulative, composite, and/or collective and should be regarded as preferable or desirable rather than stated as a warranty.
Throughout this specification, unless otherwise indicated, “comprise,” “comprises,” and “comprising,” (and variants thereof) or related terms such as “includes” (and variants thereof),” are used inclusively rather than exclusively, so that a stated integer or group of integers may include one or more other non-stated integers or groups of integers.
When any number or range is described herein, unless clearly stated otherwise, that number or range is approximate. Recitation of ranges of values herein are intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value and each separate subrange defined by such separate values is incorporated into the specification as if it were individually recited herein.
Words indicating direction or orientation, such as “front”, “rear”, “back”, etc, are used for convenience. The inventor(s) envisages that various embodiments can be used in a non-operative configuration, such as when presented for sale. Thus, such words are to be regarded as illustrative in nature, and not as restrictive.
The term “and/or”, e.g., “A and/or B” shall be understood to mean either “A and B” or “A or B” and shall be taken to provide explicit support for both meanings or for either meaning.
Features which are described in the context of separate aspects and embodiments of the invention may be used together and/or be interchangeable. Similarly, features described in the context of a single embodiment may also be provided separately or in any suitable sub-combination.
It is to be understood that the terminology employed above is for the purpose of description and should not be regarded as limiting. The described embodiments are intended to be illustrative of the invention, without limiting the scope thereof. The invention is capable of being practised with various modifications and additions as will readily occur to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023214341 | Aug 2023 | AU | national |
