AU684643B2 - Prefabricated masonry fencing system - Google Patents

Description

WO 96100338 PCTAU95100365 1 PREFABRICATED MASONRY FENCING SYSTEM Masonry fencing is by far the oldest and most sought after type of fencing since the beginning of walled structures. Most fencing is installed for security or privacy and masonry is the best type for these purposes, it is also the most difficult to build and expensive of all the types available.

All designs and types of fencing must resist wind forces for stability, this is accomplished in two ways, firstly by sheer weight and mass which results in a very thick and expensive wall, secondly by having piers or posts at appropriate intervals along the fence length anchored securely into the ground. The second method is obviously the easiest and most economical.

The usual method of constructing masonry fencing commences with the foundation consisting of a horizontal reinforced concrete beam formed by excavating a trench in the earth and after reinforcement is installed, the trench is filled with concrete.

The next step is to construct a wall from bricks or blocks up to the desired height, thickness of the wall can be varied to suit structural requirements for stability under wind conditions. Alternatively piers or buttresses may be constructed at appropriate intervals to create increased stability and strength, saving on wall thickness, sometimes these piers are reinforced to improve their performance.

This process is slow and very costly and requires considerable on site skill to achieve a satisfactory result.

The invention described herein will produce a masonry fence at less than half the cost of conventional masonry fencing and will also allow these types of fences to be assembled by unskilled labour. It can be built with a minimum of disruption to existing ground as it does not ST/AU 9 b U O 3 b RECEIVED 2 2 MAY 1996 2 require a large excavation for foundation members. As it is prefabricated it can also be taken down if needed at a later date and reassembled in the same position or at a new location.

The present invention consists in a fence post, the post being made of lightweight steel and when seen in section consists of two channel section members, the open faces of the channel section members facing each other and the inner edge of one side of one channel member being joined to the inner edge'of the corresponding side of the other channel member by a transverse member forming the web of the post whereby a channel is formed at one side of the post for the reception of an end of a masonry panel member, means being provided in or on the web to receive at the other side of the post another masonry panel member, there being provided within the post at least one stabilising torsion sleeve member constructed and arranged to prevent the buckling of the web under wind loading transmitted from the masonry panels.

The present invention also consists in a fence made up of a series of fence posts as defined above.

The term "masonry" as used in this specification means all types of brick, concrete block, stone, reconstructed stone, dense and lightweight concrete and fence members made from cement and lime based materials.

In order that the nature of the invention may be better understood preferred forms thereof are hereinafter described by way of example with reference to the accompanying drawings in which: Fig. 1 is an elevation of a typical masonry fence built using this method where a light gauge steel post i, standing and held rigidly in a post hole 2 by insitu concrete 3.

Fig. 2 is a plan drawing showing the intersection of the masonry fence panels 4 and the light steel post 1. Also shown is the method of fixing and holding the fence panels U AMENDED SHEET

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WO 96/00338 PCTIAU95/00365 3 to the post 1 by means of a fixing plate 5 and angle bracket 6. The torsion sleeve 9 is omitted for clarity.

Fig. 3 is a drawing showing in plan a masonry pier system 7 and how it assembles and attaches to the post 1 and fence panels 4.

Fig. 4 is a plan drawing of the post 1 lightweight steel section.

Fig. 5 is a plan drawing of the post section 1 and the stabilising torsion sleeve 9.

The construction procedure commences with the boring of the post foundations, the post 1 is stood in the hole 2 and inco ~khe h#e, Ch pse concrete 3 is poured xn= z securing^ in it's final position, after an adequate curing period, usually overnight, the wall panels 4 are delivered and positioned between the posts i. The steel post is made from thin gauge steel, rolled into a sectional shape that has two enlarged flange ends, offset from the web section.

Prior to the installation of the wall panels the heights and ground levels are determined, when this is done an angle bracket is fixed to the web of the lightweight steel post on the open side flush with the position of the top of each fence panel.

Next the torsion sleeves 9 are fixed in at the prescribed position (their purpose will be explained later).

The post section is designed and shaped so as to cover discrepancies in the setting out of the distances between posts and hiding the end of the prefabricated fence panel at the same time. This is achieved by using an open sided steel section for the post on one side and a recess formed into the web section on the other side. One end of a fence wall panel is then introduced into the open side of the first post, the panel is then pivoted about a vertical axis passing through the end in the post and pushed along into the recess on the web of the next post that will support it WO 96/00338 PCT/AU95/00365 4 at it's other end. In this way The wall panel does not have to be lifted higher and Lowered down to fit into the recesses. The panel is now captive and is fixed in position at any suitable time by a fixing plate 5 that is attached to the top of the wall panels and the angle bracket 6 fixed to the web installed earlier.

The bottom of the panel is resting on packing on the surface of the concrete ground pier and normally will not require any further treatment, relying on it's own weight for stability. These wall fence panels are structural elements and will span from pier to pier without any other foundation.

The post system is relatively flexible being of light gauge steel (between 1 mm and 5 mm thick), the reinforced masonry panels however are very stiff and rigid causing the deformation under load characteristics of the two elements to be quite different.

By fixing the panel at the top and the provision of the gap between the panel and the enlarged post flange sides, the two elements can freely deform individually under wind force loadings without causing friction and any stress concentrations that could crack the wall panel or buckle the steel post. This effect varies depending on the gap between the flange edges and the wall panel, the post will continue to bend under the wind loading conditions until the wall panel and post flange edges bear against one another or the post buckles.

It is possible that a beneficial effect could be obtained by having the gap small so that a stiffened designed wall panel, in fact stiffens the post by distributing the load more evenly in a flat plane over the wall height.

This effect would then concentrate more of the post buckling forces in the area between the concrete pier and WO 96/00338 PCT/AU95/00365 5 the bottom of the wall panel as the post would want to hinge at that point. This very highly stressed region could then be easily strengthened up by the use of a suitable torsion sleeve.

As previously stated the post has an open side to facilitate assembly and lower the post cost, the disadvantage of this is that when the post is under wind load conditions, transmitted via the fence panels, it will be susceptible to buckling action as the flange edges of the section can freely rotate.

The post, anchored rigidly in the concrete base resists the cumulative wind forces by it's stiffness cantilevering from it's rigid base, the buckling forces are concentrated immediately above the concrete ground pier causing the post to fail around where the flanges can rotate around the web.

This will be in the lower one third of the overall height of the post above the concrete in ground pier.

It is a feature of this invention that solves this problem without having to increase significantly the sectional thickness of the post material. This is accomplished by installing a torsion sleeve 9 at the appropriate height from the concrete pier to prevent the free flange post edges from rotating or moving around the eccentric loading that is transmitted from the web.

This sleeve as shown in Fig. 5 is approximately 50 mm wide and manufactured from relatively thin gauge steel, it is fixed onto the web of the post and also through where it engages the flanges at both it's edges. It simply restrains the flange edges from movement, keeping them in their correct position for maximum strength and rigidity.

The buckling stresses placed on the post are the most severe immediately above the point of embedment of the post in the concrete, it is this area in which the torsion sleeve is to be installed additional torsional sleeves can be WO 96/00338 PCT/AU95/00365 6 installed at any other position in the post that may become necessary. It can in extreme situations be installed after the installation of the fence panels, however in this case it can not be fixed to the web of the post which will slightly diminish it's performance.

The torsion sleeve can be as short as 30 mm or if required up to 800 mm long, in this longer instance it would also act like a reinforcing sleeve in the areas of highly concentrated stress that occur in the lower third of the post, it could also, as a longer sleeve be partly embedded in the concrete pier to assist the post immediately adjacent to and above the concrete pier.

In Fig. 5 the sleeve edges are shown to follow the contour of the post flange so as to make a snug fit and this is preferred, however a similar effect could be obtained through a suitable means of fixing the bracket edges to the flange. For example, this fixing method could be by rivets, screws or welding as it's purpose is to reinforce and prevent the flange from rotating.

In effect the torsion sleeve stabilises and stiffens the post only where it is required and increases the efficiency of the post section using less material and therefore lowering cost.

If a masonry brick pier is required for aesthetic reasons Fig. 3 indicates how that can be achieved, in the case shown a thin steel channel 8 is cast into the brick pier 7 when manufactured and fits around the projecting flange of the post, the pier can be fixed by screwing to the post at any point if a hole is either left or drilled in the brick joints for access. Alternatively the brick pier may be fixed at the top by a fixing plate and bottom if it can span the full height of the fence.

The masonry pier could be made of any thickness and almost any composition of materials using sand, cement or WO 96/00338 PCT/AU95/00365 7 lime eg., resin bonded artificial stone, brick facings or aerated concrete.

The prefabricated fence capping 10 which like the vertical pier 7 is similarly made with a longitudinal fixing channel shaped steel insert is then fixed on top of the wall fence panels, finally a cap is fixed on top of the post and the fence is complete. By necessity neither the masonry pier or the masonry capping require a metal channel insert to become workable, however they would require a recess to be able to fit over the projecting post, but could be fixed to either the post or the fence panels by a variety of different methods.

Other than the post hole and concrete the entire masonry fence can be constructed and fixed in position with a simple screwdriver by unskilled labour.

The size of the wall fence panels can vary, in thickness from 50 mm to 100 mm, in height up to 3 metres and in length up to eight metres. The optimum size wall fence panel would be 50-70 mm thick, 1.5-2 metres high and 3-4 metres long.

Panels of this size require a crane or similar lifting and transport system to place them in final position, this is sometimes difficult due to access problems and the panels have to be reduced accordingly down to a weight that allows them to be more easily handled. Sometimes there is only access for manual installation and in this case the panel size or the weight must come down significantly, this is achieved by both shortening the length and decreasing the height so that the panels will sit on top of one another, slotted into the same post configuration and still assembled and fixed in the same way.

Alternatively the size can be affected by the weight of the material which could be significantly reduced, eg., by using aerated concrete panels with a density down to 600 kgs per m3. Further, lightweight concrete bricks or blocks WO 96/00338 PCT/AU95/00365 8 could be used to simulate the finished masonry appearance.

These could be specially shaped to facilitate the use of specially designed reinforcing in the horizontal bed joints as well as the vertical core holes and perpendicular joints.

Obviously if the length of the panels is shortened then the number of posts increases so that the panel length is always kept as long as possible. The costs associated with the posts are a critical item as the post installation cost remains fairly constant even though increasing the number decreases the wind loadings on each one, therefore reducing the number and cost of the post system is critical to reducing overall costs.

When panel weight becomes a critical issue panels can be made lighter without decreasing the length by decreasing the height and stacking them on top of one another so that making up of one large fence panel 4 metres long and 2 metres high could consist of four panels 4 metres long and metre high. When stacked on top of each other this way each panel would have to be fixed to the web at it's top so that this configuration would require four separate fixings, in this way under wind load conditions the panels could articulate and deflect in a similar manner to the post.

Another way would be to bond or structurally join the panels together so that they would act as one, the only fixing required would be at the top as originally described.

The fence panels require horizontal reinforcing to be able to span economical distances of over three metres, this in turn will vary with the type and thickness of the material used. Special shaped masonry units or bricks may be required to facilitate enough space in the bed joint for that reinforcing, alternatively special reinforcing may be required.

In it's preferred form and the panel 4 were to be manufactured from clay or concrete brick elements, any WO 96/00338 PCTIAU95100365 9 suitable method of manufacture may be used provided that the panels so manufactured have sufficient strength to perform the structural requirements necessary to function as a suitable fence panel 4.

If the fence panel 4 was required to be double sided or have a face brick finish on both sides the mortar application procedure as described in the above patent would need to be modified as follows, all excess mortar would have to be screeded off as clean, next a retardant chemical is applied by spray or within a manual applicator.

The following day the back surface of the panel 4 so treated above is hosed down with a high pressure water spray which removes the excess and retarded mortar material, leaving the back side of the panel clean with the bricks exposed. The panel 4 after curing is then suitable for transport and installation.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

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Claims (4)

1. 2. A fence post as claimed in claim 1 wherein each channel section member has an inwardly directed flange along each of its longitudinal edges the said means being constituted by the inner edge of one flange of one channel member being joined to the inner edge of the corresponding flange of the other channel member by the web to form a channel to receive the said other masonry panel member.
2. 3. A fence post as claimed in claim 1 or claim 2 wherein the stabilising torsion sleeve consists of a sheet metal member the ends of which are shaped to bear on the said channel section members and having a portion at the centre thereof bearing against the web of the post.
3. 4. A fence made up of a series of fence posts as claimed in claim 1 or claim 2 adjacent posts being joined by a masonry panel member or members. fy) L AMENOED SHEET IPF /AU
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