GB2379963A

GB2379963A - Jointing element for tubular rails

Info

Publication number: GB2379963A
Application number: GB0122877A
Authority: GB
Inventors: Donald Mackay
Original assignee: BRIDGE PARAPETS Ltd
Current assignee: BRIDGE PARAPETS Ltd
Priority date: 2001-09-22
Filing date: 2001-09-22
Publication date: 2003-03-26
Anticipated expiration: 2021-09-22
Also published as: GB2379963B; GB0122877D0

Abstract

A jointing element (11) for end to end connection of tubular rails comprises an elongate body (19) adapted to fit closely with juxtaposed ends of two rails (12, 13). The jointing element (11) includes extensions (18) of gradually reducing width (i.e. tapered) at each end of the body (19).

Description

Title-Improvements relating to vehicle parapets This invention relates to improvements in vehicle parapets, and in particular to improvements In the connection of rails forming part of such parapets.

Vehicle parapets are very commonly installed on bridges of all sorts, in particular road bridges. The parapets are present to increase safety, in that they act as a barrier to restrain an impacting vehicle to prevent it from falling from the bridge and to deflect the vehicle back onto the road.

A vehicle parapet typically comprises vertical support posts spaced along the edge of the bridge carrying one or more rails which are aligned parallel to the ground.

Each rail typically comprises rail sections that are connected by means of an internal jointing element (commonly referred to as a jointing sleeve) to which the two connecting rails are attached, commonly using bolts. Such a jointing sleeve normally takes the form of an extruded component that fits closely within the ends of the abutting rails.

It has recently been established that, contrary to established belief, two rails connected with a conventional jointing sleeve may show a substantial reduction In bending strength and deflection strength, when compared with a similar rail without a joint. This is obviously a major disadvantage, increasing the likelihood of the failure of the vehicle parapet.

There has now been devised an improved form of jointing element that overcomes or substantially mitigates the above-mentioned and/or other disadvantages of the prior art.

According to a first aspect of the invention, there is provided a jointing element for the end-to-end connection of tubular rails, said jointing element comprising an elongate body that is dimensioned and configured to fit closely within the

juxtaposed ends of two rails, wherein the body is provided with extensions of gradually reducing width at each end thereof.

The jointing element according to the invention is advantageous primarily in that it eliminates the sharp edge at the end of the conventional jointing element that fits closely within the rail and at which the rail can shear. A rail connected with a jointing element according to the invention as part of a vehicle parapet is therefore less likely to shear on the impact of a vehicle.

The extensions may gradually reduce In width by virtue of having straight sides that are disposed at an angle to the longitudinal axis of the jointing element, or curved sides. In general, the extensions may take any form provided that a relatively sharp edge does not exist close to the rail.

The extensions are most preferably tapered. The angle of taper is preferably between 50 and 300 to the longitudinal axis of the jointing sleeve, more preferably between 5 and 20 , and especially between 5 and 10 , eg 6 to 8 .

For ease of manufacture, the extensions are preferably formed by cutting away the central sections of the extensions, most preferably of generally rectangular shape, and controlled pressing of the limbs of each extension that are so formed towards each other, in order to gradually reduce the width of the extensions.

The jointing element is preferably of tubular or hollow construction. Preferably, the body is provided with longitudinal grooves or recesses along its side surfaces.

Such grooves or recesses can accommodate rivets or other fasteners fixed to the rail.

According to a second aspect of the invention, there is provided a railing or parapet structure suitable for a bridge or the like, which parapet structure comprises one or more rails supported by a plurality of upright support elements,

said rails comprising rail elements connected end-to-end by means of jointing elements according to the first aspect of the invention.

The rails may be made of any suitable material, however it is common that the rails are made of metal. The rails are most commonly formed by extrusion in aluminium. The rails are commonly tubular and can have any suitably shaped cross-section such as square, rectangular, trapezoidal, circular or elliptical. The rails are commonly cut to manageable lengths, aiding the manufacture and transportation of the rails. Such a length might typically be of the order of 10m, eg 12m.

The jointing element may range widely in size, the size of the jointing element being commensurate with the size of the rails that are to be connected together.

Typically, however, the body of the jointing element may have a length of from about 200mm to about 800mm, eg 300mm or 600mm. The lengths of each extension may range from about 10% of the length of the body to about 40%. The overall length of the jointing element (the length of the body and the two extensions combined) may typically range from about 250mm to about 1 m.

The width, depth and cross-sectional form of the body of the jointing element will be such as to provide for a close fit of the body within the ends of the rails.

Typically, these dimensions will be in the range of a few tens of millimetres to a few hundred millimetres, eg the cross-sectional dimensions (width, depth or diameter) of the body may be in the range 50mm to 300mm.

According to a third aspect of the invention, there is provided a method of assembly of a railing for use in a parapet structure, which method comprises the steps of (a) inserting a first end of a jointing element according to the first aspect of the invention into one end of a first rail, (b) fastening the first rail to the jointing element, (c) fitting a second rail over the other end of the jointing element, and

(d) fastening the second rail to the jointing element The jointing element is preferably provided with means for fastening the rails to the jointing element. Such means may take the form of fixing holes. The jointing element may be secured to the rails using bolts or the like which pass through the fixing holes and corresponding fixing holes provided in the rails. The fixing holes In the jointing element are preferably elongated to accommodate thermal expansion and contraction of the rails during use. Bolts or other fasteners may pass vertically or horizontally through the rails. Another fastening method involves the use of setscrews passing through the rails into engagement with the jointing element The jointing element may be made of any suitable material having the necessary strength and durability. However, it is preferred that the jointing sleeve is made of metal, and most preferably aluminium. The jointing element may be formed by extrusion in aluminium. The fixing holes and the cut out sections can be punched out of the extrusion, either before or, more preferably, after cutting of the extruded profile to the required length. The limbs of each extension may then be pressed towards each other to form the desired reduction in width.

The invention will now be described in grater detail, by way of illustration only, with reference to the accompanying drawings, in which Figure 1 is a plan view, partly In section and showing hidden detail, of a prior art form of joint between two rails forming part of a horizontal vehicle parapet rail ; Figure 2 IS a sectional view on the line ll-ll in Figure 1; Figure 3 is a view similar to Figure 1 of a joint in accordance with the present invention,

Figure 4 is an end view of a jointing sleeve according to the invention forming part of the joint of Figure 3 ; Figure 5 is a perspective view of the jointing sleeve ; Figure 6 is a longitudinal section on the line VI-VI in Figure 5 ; Figure 7 IS a perspective view showing an intermediate stage in the assembly of the joint of Figure 3 ; and Figure 8 is a perspective view of the assembled joint.

Referring first to Figures 1 and 2, a conventional (prior art) joint connecting the juxtaposed ends of two tubular rails (2,3) that form part of a vehicle parapet is made using a jointing sleeve (1). The jointing sleeve (1) is typically 600mm in length and is dimensioned and configured to fit closely within the ends of the two rails (2,3), as shown most clearly in Figure 2.

The jointing sleeve (1) is formed with two series of five fixing holes (4a, 4b), aligned centrally along the longitudinal axis of the upper (as viewed in Figure 1) surface of the jointing sleeve (1). Similar fixing holes (not visible) are provided in the lower surface of the jointing sleeve (1), in registration with the holes (4a, 4b) in the upper surface, so that bolts (not shown in Figures 1 and 2) can be passed directly through the jointing sleeve (1). The jointing sleeve (1) may alternatively be drilled and tapped with corresponding expansion slots being punched in the rail ends.

In assembling the joint, the jointing sleeve (1) is inserted into the end of one of the rails (2,3) and bolts or the like are passed through holes in the rail (2,3), those holes being either drilled on site or preformed in the rail (2,3), and through the fixing holes (4a) in the jointing sleeve (1). Nuts (not shown) are applied to the ends of the bolts that project through the underside of the rail (2,3), or in the case

of a jointing sleeve (1) which is drilled and tapped setscrews are fitted through slots in the rails (2,3). The second of the rails (2,3) is then fitted over the other end of the jointing sleeve (1) and secured by bolts in a similar manner to the first of the rails (2, 3).

The fixing holes (4a, 4b) are sufficiently elongated to accommodate thermal expansion and contraction of the rails (1,2) during use For the same reason, a small gap (5), of approximately 10mm, is present between the juxtaposed ends of the rails (2,3) in the completed joint-see Figure 1. The gap (5) may be larger, e. g 16mm or more, depending on the likely degree of thermal expansion The illustrated jointing sleeve (1) is of uniform cross-section throughout its length and is most commonly formed by extrusion in aluminium. Longitudinal grooves (6) (shown as hidden detail in Figure 1) are formed along the side walls of the jointing sleeve (1). The grooves (6) are positioned centrally on the side surfaces of the jointing sleeve (1), as shown in Figure 2. After extrusion, the extruded profile is cut to length and the fixing holes (4a, 4b) in the upper surface, and also those in the lower surface, are punched out or drilled and tapped. It can be seen from Figure 1 that the ends of the jointing sleeve (1) are cut square, such that the ends have relatively sharp edges.

Turning now to Figure 3, a jointing sleeve (11) in accordance with the invention is of broadly similar construction to the prior art jointing sleeve (1) described above, save that the jointing sleeve (11) has tapered end sections (18). The jointing sleeve (11) thus comprises a main body (19) that is similar in shape and dimensions to the prior art joining sleeve (1) and two end sections (18) that are formed integrally with the main body (19). Two series of fixing holes in the upper surface (14a, 14b) and the two corresponding series of fixing holes in the lower surface (not visible) are positioned similarly with respect to the centre of these surfaces as in the prior art jointing sleeve (1). As in the prior art described above, the fixing holes (14a, 14b) are elongated to accommodate thermal expansion and

contraction of the rails (12,13) in use. A gap (15) is provided between the juxtaposed ends of the rails (12,13) for the same purpose. As in the prior art, the fixing holes may alternatively be drilled or tapped.

The jointing sleeve (11) is formed with a generally rectangular section of the upper and lower surfaces at each end of the jointing sleeve (11) having been cut away These cut-away sections of the jointing sleeve (11) extend from each end of the main body (19) of the jointing sleeve (11) along the longitudinal axis of the jointing sleeve (11) to the ends of the jointing sleeve (11). When viewed in plan (as in Figure 3) the end sections (18) are thus generally of C-section, the limbs of each end section (18) being pressed together somewhat in order to create the desired tapered form of the end section (18). In order to facilitate the pressing together of the two limbs in this way, and to maximise the ability of the assembled joint to withstand bending of the rails (12,13), the innermost corners of each cut-out in the end section (18) are radiussed.

The main body (19) of the jointing sleeve (11) typically has a width of 120mm. The end-sections (18) gradually reduce in width as they extend longitudinally away from the main body (19) of the jointing sleeve (11) so that the extreme ends of the end sections (18) are approximately 100mm in width. The side surfaces of the jointing sleeve (11) retain a similar form to the prior art jointing sleeve (1) along the entire length including the end sections (18), the side surfaces incorporating longitudinal grooves (16).

The jointing sleeve (11) is formed by extrusion in aluminium. After extrusion, the extruded profile is cut to length and the fixing holes (14a, 14b) and the corresponding holes in the lower surface, and also the cut-outs in each end section (18) are punched out. The limbs of each end section (18) are pressed towards each other to form the desired taper.

In use, the Jointing sleeve (11) is used to form a joint between two rails (12,13) as follows First, the jointing sleeve (11) is inserted into one end of one of the rails (13) and bolts or the like are passed through holes in the rail (13) and through the fixing holes (14a) In the jointing sleeve (11), as shown in Figure 7. Nuts (not shown) are applied to the ends of the bolts that project through the underside of the rail (13). The second of the rails (12) is then fitted over the other end of the jointing sleeve (11) and secured by bolts in a similar manner to the first of the rails (13) creating a fully assembled joint as shown in Figure 8. As in the prior art, the rails (12,13) may alternatively be secured by means of setscrews locating in drilled and tapped holes In the jointing sleeve (11).

A vehicle parapet consisting of tubular rails (2,3) connected by the pnor art jointing sleeve (1) has been found to have a reduced strength in bending of typically 40% and a reduced deflection strength of typically 60% compared to a single rail with no jointing sleeves. The jointing sleeve (11) in accordance with the invention Improves this by eliminating the sharp edge at the end of the part of the jointing sleeve that fits closely within the rail and at which the rail can shear, and moves the end of the jointing sleeve further away from the fixing holes (14a, 14b). The jointing sleeve (11) in accordance with the invention may increase the capacity of a parapet rail considerably in load capacity and deflection capacity, compared with a rail formed with conventional jointing sleeves.

Claims

Claims 1. A jointing element for the end-to-end connection of tubular rails, said jointing element comprising an elongate body that is dimensioned and configured to fit closely within the juxtaposed ends of two rails, wherein the body is provided with extensions of gradually reducing width at each end thereof.
2. A jointing element as claimed in Claim 1, wherein the extensions are formed by cutting away the central sections of the extensions and by pressing the limbs of each extension that are so formed towards each other.
3 A jointing element as claimed in Claim 2, wherein the cut away central sections are of generally rectangular shape.
4. A jointing element as claimed in any preceding claim, wherein the jointing element is of tubular or hollow construction.
5. A jointing element as claimed In any preceding claim, wherein the body of the jointing element has a length of from 200mm to 800mm
6 A jointing element as claimed in any preceding claim, wherein the jointing element is made of aluminium.
7. A jointing element as claimed in Claim 6, wherein the jointing element is formed by extrusion in aluminium.
8. A jointing element as claimed in any preceding claim, wherein the jointing element is provided with means for fastening the rails to the jointing element.
9. A jointing element as claimed in Claim 8, wherein the means for fastening the rails to the jointing element take the form of fixing holes.

<Desc/Clms Page number 10>

10 A railing or parapet structure suitable for a bndge or the like, which parapet structure comprises one or more rails supported by a plurality of upright support elements, said rails comprising rail elements connected end-to-end by means of jointing elements according to any preceding claim.

11 A method of assembly of a railing for use in a parapet structure, which method comprises the steps of (a) inserting a first end of a jointing element according to any one of Claims 1 to 9, into one end of a first rail, (b) fastening the first rail to the jointing element, (c) fitting a second rail over the other end of the jointing element, and (d) fastening the second rail to the jointing element.