GB2511030A

GB2511030A - Crash barrier bracket

Info

Publication number: GB2511030A
Application number: GB1223004.1A
Authority: GB
Inventors: Darren Copeland; Anthony Everitt
Original assignee: Varley and Gulliver Ltd
Current assignee: Varley and Gulliver Ltd
Priority date: 2012-12-20
Filing date: 2012-12-20
Publication date: 2014-08-27
Anticipated expiration: 2032-12-20
Also published as: NZ618979A; EP2746461A1; GB2511030B; DK2746461T3; AU2013270610B2; EP2746461B1; AU2013270610A1; GB201223004D0

Abstract

The bracket 28 is made from a continuous sheet of metal bent into a shape. In use, mounted to a post 12 and supporting a rail 24, has a uniform cross section across a horizontal plane. The bracket has parallel front 40 and rear 42 panels and interconnecting sides. The shape of the cross section provides two deformation modes which deform at different impact levels. Each side may include a pair of web portions the first web portion of each side extends inwardly towards the other from one respective end of the front panel and away from the rail at an angle of less than 45 degrees. The second web extends from the inward ends of the first webs and are longer than the first webs and each joins a respective end of the rear web at an acute angle of more than 45 degrees.

Description

Crash Barrier Bracket Reid of the Invention The present invention relates to a bracket for supporting a rail of a roadside crash barrier or parapet.

Sackqround Roadside crash barriers and parapets are designed to prevent vehicles from leaving the road along which they are travelling in accordance with certain design standards In recent years narticularly in the European Union, the standards have been revised requiring the barrier design to be proven in crash tests (as specified, for example in EN 1317) In the case nf parapet designs for use on bridges or steep hillside roads th crash tests require that both small vehicles (oats) and larger vehicles, such as trucks are preventeo from leaving the road In the case of a small vehicle or relatively low impact crash it is preterable for the parapet to have some flexibility to avoid bringing a vehicle to too sudden a stop However, for higher impacts. particularty with larger vehicles, the barrier needs to be stiffer to absorb more of the impact and prevent the vehicle passing too far over the edge of the road.

With this in mind Various designs have been proposed, based on a series of posts or uprights, anchored to the ground, usually in a concrete footing, at the roadside. A number of rails at varying heights are supported off the posts by brackets, When a vehicle impacts a rail, the impact is transmitted through the brackets to the posts. To provide the requked flexibility at low impact, and stiffness at higher impacts, brackets have been designed having two or more parts, 1 which a first bracket part collapses relatively easily under an impact, When the. first part has collaped by a certain amount, the mpact is then transmitted intd the second, stiffer part which will only collapse under a significantly higher impact. However, a problem with these désighs s in their relative cost and complexity, especially in the installation of the multi..part support brackets, The barriers and brackets disclosed herein have been conceived with the foregoing in mind.

Summary

According to one aspect, there is provided a bracket for supporting a rail of a roadside crash barrier from a support post. The bracket, has the form of a continuous sheet of metal bent into a shape., which, when mounted to a post and supporting a rail, has a uniform horizontI cross-section, including parallel front and rear panels for mounting to the rail and post respectively, and interconnecting sides. The shape of the cross-section provides a'first deformation mode of the bracket in the event Of' an irnpct to the rail exceeding a first impact level and a second mode of deformation of the bracket in the event of an impact exceeding a second, higher impact level.

The bracket may be formed from two or more sheet metal parts welded together.

In embodiments the horizontal cross-section is made up of straight web sections joined at bends.

In embodiments, the rear panel is adapted farattachrnent centrally to a front face of the support post and nas ends separated by a lateral width that is greater than the width of the front face of the post. Preferably, the rear panel has a width of between 1.75 and ?.25 times the width of the front face of the post.

In embodiments the front panel has ends. that are separated by a distance that is greater than the width of the front face of the post and the interconnecting sides of (tie bracket each extend trom one of the ends of the front pnel to a corresponding one of the ends of the rear panel. Each of the interconnecting sides may comprise a pair of web portions, wherein first of the web portions extend inwardly towards each other and away from the rail at an angle to the rail of less than 45 degrees, preferably between 20 degrees and 40 degrees Second of the web portions extend from the nward ends of the first web portions to the ends of the rØar panel, the second web portions being longer than the first web portions and adjoining the ends of the rear panel at acute angles of more than 45 degrees preferably between 50 degrees and 70 degrees According to another aspect there is provided a roadside parapet comprising a plurality of Øosts supporting.a rail, At least one of th.e posts upods th rail, by way of a.

bracket having the form Of a continuous theet of' metal bent into a shape, which, when mounted to the post and supporting I he rail, has a uniform horizohtal cross-section that includes paraflel front and rear panels for attaching to the rail and post respectively, and interconnecting sides The shape of the Gross-section provides a first deformation mode of the bracket iP the event ol an impact to the rail exceeding a first impact level, and a second mode of deformation of the bracket in the event of an impact exceeding a second, higher impact level.

The paapet may further comprise one or more additional rails mounted to the posts above the aforesaid rail The aforesaid rail supported on the bracket preferably extends a greater distance from the post towards the road than the additional rails

Brief Description of the Dra,jg

Figure 1 is an elevational cross-section through a post of parapet supporting three rails.

Figure 2 is a plan view in the direction of arrows A-A of Figure 1 showing a bracket supporting one at the raits, Figure 3 ra a plan view snowing the bracket of Figures 1 and 2 rn a first mode of deformation Figure 4 is a plan vrew showing the bracket of Figures 1 and 2 in a second mode of deformation, Detailed Desp4ption Refernnq to Figure 1 there is shown part of a parapet 10 having a post 12 with a base 14 The post 12 is secured at base 14 to a olinth 16 which is typically a concrete olinth farming the edge of a bndge or raised roadway The post 12 is one of a series of posts spaced at intervals of typically a few meters from each other iong the edge of the.

road As snown in Figure 1 tne road is to the nght of the parapet, which is designed to prevent stray vehicles from leaving the roadway and dropping over the edge to the left of the parapet The illustrated parapet has three rails, 20, 22, 24 supported by the post 12 Die upper two rails 20, 22 are secured directly to a front face 8 of the post by bolts 26.. The upper rails 20, 22 are formed of lengths a rectangular box-secfron (typically steel) oriented with their longer sides horizontal and sho#er sides vertical The lowest rail 24 is supported away from the post by a bracket 28.. The bradket 28 is secured by bolts.3Q to the front fact 18 of the post 12 and the lowest rail 24 is secured to the bracket 28 by bolts 3:2 Also shown in Figure 1 are connecting sleeves 34 surrounding each of the rails 20, 22, 24. These sleeves are niy positioned at locations at the ends of each length of a rail where it is connected to another length of red at the same height Vertical bolts 36 38, secure the ends of the length of rail to the sleeves 34.

The bracket 28, which supports the lowest rad 24 is designed to have a progressive or plural-mode dforrnation ri the everit of an impact from a vehicle on the lowest rail 24.

The lowest rail 24 extends kirther towards the road than the upper to rads 20 22 This mSn that it WHI be the lowest rail 24 that will be. struck first by an impacting vehicle. In the case of a car or other small Vehicle it may only be the lowest rail 24 that will be struck, especially it the vehicle impact is only a glancing blow To limit the chances of injuring the occupants. of the impacting vehicle, it is important that the lowest rail does riot present too stiff an object so that it does not bring the vehicle to too u'dden a stop and does not cause excessive damage. .to the vehicle. Therefore, in the first mode of deformation the bracket is relatively flexible, ailowing the rail 24 to move a significant distance under the impact.

However., if' the lowest rail 24 is struck by a larter vehicle, or is struck with a high impact by a sniaUer vehicle, then the deformation of the bracket in the first mode will not be sufficient to arrest or deflect the vehicle, or to absorb aD of the impact There.fØre, after the bracket, has been deformed by a certain amount in its first deformation mode, it is designed to undergo a second stitfei mode of deformation In this stifler mode, the rail 24 does not move far and most of the impact is transferred to the post 12. In addition a larger vehicle impacting the parapet 10 will contact the upper rails 20, 22 after the lowest rail 24 has deformed to its limit (i.e. collapsed) under the first mode of deformation.

A prefened embodiment of the bracket 28 is shown in Figure 2 Equivalent components have, the same reference numerals as used in Figure 1. The bracket 28 is hOwn mounted to post 12, and rail 24 is shown mounted to the bracket 28 For clarity the fasteners bolts) securing the bracket 26 to the post 12 and rail 24 have been omitted The. bracket 2 has a shape that provis the two modes of deformation as described above, and as wilf'be discussed further below with refc.rence to Figures 3 and.4. The bracket 28 is preferably has the form of a continuous sheet of metal bent into the shape shown. Although'the bracket may be formed from.a single sheet of metal, it may also conveniently be formed by weldn.g two or more sheet metal parts together to provide the continuous sheet metal form.:shown. As shown in plan View, mounted to:the post 12 and supporting*the rail 24, the bracket has a uniforth horizontal cross-section that includes parallel front.40 and rear 42. panels. Front panel 40 is mourted to the rail 24 and rear panel 42 to the post 12 The front and rear panels 40, 42 are interconnected by aide panels, 44,. 46 to be discussed further below.

The rear panel 42 includes means, suchas fking hoS for receiving bolts, for attaching it centrally to the front face 18 of the post 12 The rear panel 42 extends either side of the post l2to ends.48a, 48b. The rear panel 42 has a lateral width That is significantly greater than the width of the front face 18 of the post 12. Typically, the width of the rear panel.42 may be about twice, and is preferably between 1.75 and 225 times, the width of the front face 18 of the pcst 12 The front panel 40 may extend as a continuous panel (as Thown in Figure 2) along the side Of the rail 24 mounted to ii.. However, it is also possible or the front panel 40 not be ccnhinuous, but to have separate portions extending inwardly from its outer ends with a gap between the pontons The front panel 40 or the separate portions, include means such as fixing holes for receiVln bolts for attachment to the rail 24 The front panel has outer ends 50a, Sob thai. are separated by a distance similar to the width of the rear panel 42 and more than the width of the front face 18 of the post 12.

The interconnecting side panels 44, 46 are each formed as a pair of we sections 52a, 54a and 52b, 54b, interconnecting the front and rear panels 40, 42. The side panel44 extends from the end SOs of the front panel 40 to a corresponding end 48a of the rear panel 42 The side panel 46 extends from the end 50b of the front panel 40 to a corresponding end 48b of tha rear psnel 42. Each of the side panels 44. 48 includes a first shorter web Dodion 52a 52b, and a second, longer web portion 54a 54b The first shorter web oortions 52a, 52b extend inwardly trom the enos 50a SOb of the front ao panel 42 towards each other and away from the rail at an angle to the rail of less than degrees, preferably in tne range 20 to 40 degrees The second longer web portions 54a, Mb extend from the inward ends 58a, Sb of the first, shorter web.

pqdion 52a, 52b to the ends 48a, 48b of the rear panel 42. The second web portions 54a 54b join ihe respective ends 48a, 48b of the rear panel at acute internal angles of more than 45 degrees, preferably in the range 50 to 70 degrees. The angle of the bends between the first and second webs at the locations SBa, 58b are preferably in the range 80 to 100 degrees.

As shown in Figure 2, the term "end' is used to describe the locations of the bends between the connecting panels or webs Thus the "enas" 48a, 48b bOa, SOb 58a, 58b are in fact he locations of bends between one straight section (panel or web) and another In the embodiment shown because the bracket 28 is formed by bending from a sheet of metal of a certain thickness, these bends each have a radius of curvature FiQure 3 shows a first mode of deformation of the bracket 28 in the event of an impact to the rail 24. Equivalent components have the same reference numerals as used in Figures 1 and'2. Because the rear panel 42 is wider than the front face 18 of the post 12, the impact is transmitted through the bracket 28 to the post 12. The impact force applied to the rail 24 is transmitted into the front panel 40, along the side panels 44, 46 to the ends 48a, 48b of the rear panel 42. The reaction to the impact force by the post 12 occurs in the central portion of the rear panel 42. the rear panel 42 is therefore subiected to bending moments which are highest at the positions 60a 60b adjacent the edges of the front face 18 of The. post 12.

As shown in Figure 3. the hrack.t 28 starts' to deforrh at the positions eon, 60b where the bending moments are largest such that the ends 48a, 48b of the rear panel 42 are pushed backwards relative to the, front face 13 of the post 1. the effect of this deformation of the bracket 28 is fpr the angle btween' the secohd, longer web portions 54a,. 54b of the side paneLs 44, 46 and the deformed rear panel 42 to reduce.

eventually to a point where it resists further deformation (i.e. becomes stifler). In this first mode of deformatioh there is relative large degree of movement in the bracket 28, meaning that the rail 24 can be pushed a significant distance towards the post 12 if the impact forces are high enough (e g because the impact is from a larger vehicle) then further deformatinn of the rent panel 42 may continue but at a siower rate as the $tiffness increases, At a certain, point, the stiffness of the deforming rear panel 42 will equal or exceed that of other parts of the bracket 28 In these circumstances as showh in Figure 4, a second mode of deformation occurs. Equivalent components have the same reference nuterais as used in Figures 1 to 3. The. second mode of deformation involves a closing of the argies of' the bends at the locations SOa, 5Db, 58a. 58b between the front panel 40 the first, shorter web portions 52a, 52b. and the second, longer web portions 54a, 54b. In addition, in this second mode, there is a continued reduction of the angle of the bends at the locations 48a 48b between the ret panei42 and the longerweb portions 54a, 54b. The second mode of deformation results in a flattening of the bracket towards the front panel 40 as shown The second mode of deformation resufta in a relatively small movement of the rail towards the post (compared with the first mode) meaning that there is a grEater resistance to the impact of: the vehicle and larger forces are transiifted tQ the pøst. 12. It will be appreciated that th transdion between the fitst and second modes of deformalion riced not be a sudden or instantaneous, but that there may be a progressive transition.

Once the bracket 28 has been deformed to its full extent, as shown in Figure 4, any additional load is transferred directly to the post 12. The rail. 24 will then start to bend and deflect the post 12 with forces being transfened into the anchorage in the plinth 18 atthepostbasei4.

Fgure 5 illustrates the modes of deformation of the bracket 28 mounted to the post 12 (the rail and fixing bolts have been removed for clarity), with the shapes of the bracket after deformation in eaci mode superimposea Equidalent components have the same reference numerals as used. in Figures 1 to 4. The initial bracket shape 28a is shown in solid outline; the Chape 28b follows deformation.in the first mode; and the shape 28c follows deformation in the second mode.. The front panel 40 is shown as 40a in the undeformed bracket, 40b after the first mode deformation arid 4Cc after the second mode deformation. As can be seen, the front panel 40 moves further towards the post 12 during deformation in the first mode, and does not move as far during deformation in the second mode Also, it can be seen ui Figure 5 that the width of the front panel 40 is reauced as the bracket is deformed This is a consequence of the deformation of the side panels 44, 46 of the bracket and absorbs: some df the energy of the impact.

It is a particular advantage of the bracket arrangement described above tnat a single bracket component can be used to achieve plural modes of deformation and a progressive transition in the stiffness in the event of a impact The use of a single compoflept bracket not only reduces material and product costs compared with known multi-component bracket systems, but also simplifies the installation of a barrier or parapet. In addition, the use of a single bracket simplifies maintenance and repiacement after an impact.

Claims

CLAIMS: 1. A bracket for supportFn.g a rail of a roadside crash baffler from a support post.the bracket having the form of continuous sheet of metal bent into a shape, which, when mounted to a post and supporting a rail, has a uniform horizontal cro-secf ion including parallel front and rear panels for mounting to the rail and post respectively, and Interconnecting sides, wherein the shape of the cross-section provides a first deformation mode of the bracket in the event of an impact to the rail exceeding a first impact level, and a second mod of øeformtio,n of the bracket in the event, of an impact exceeding a secbnd, higher impact level.
2 The bracket of cLaim 1 wherein the horzontal cross-section is made up of straight web sections joined at bends. 1.5
3. The bracket of claim 1 *r claim 2 wherein the rear panel is adapted for attachment centrally to a front face of the support post and has Separafed by a lateral width that is greater than th.e width of the front face of the post.
4. The bracket of claim.3 wherein the rear panel has a width of between 1.75 and 225'tirnes the width of the front face. of the post.
5. The bracket of any preceding claim wherein each of the interconnecting sides corti'prises a plurality of straipht..web sections.
6. The bracket of any of claims 3 to 5. wherein, the front panel has ends that are separated by a distance that is greater than the width of the front face of the post and wherein the interconnecting sides of the bracket each extends from one of the ends of the front panel to a corresøonding one of the ends of the rear panel.
7, The bracket of claim 6 wherein each of the. interconnectinq sides comprises a pair of web portions, wherein the first web portions extend inwardly towards each other and away from the rail a an angle to the rail of less than 45 degrees, and wherein the second web portions extend from the inward ends of the first web portions to the ends of the rear panel, the second webs being longer than the first webs and adjoining the $nds of the rear panel at acute angles of more than 45 degrees.
8, The bracket of claim 7 wherein the first web portions extend inwardly towards each other and away from the rail at an angle to the rail of between 20 degrees and 40 degrees.
9. The bracket of claim 7 or claim 8. wherein the second acjoin* the ends of the rear panel at an angle of between 50 degrees and 70 degrees.
10. The bracket of any preceding claim wherein the bracket has a depth between the post and the rail that is between 50% and 75% of the lateral width of the rear panel of the bracket.
11. A bracket for supporting a rail of a roadside crash barrier from a support post, the bracket comprising; a rear panel adapted for attachment centrally to a front face of a post and having enos separated by a lateral idth that s greater than the width of the front face of the post; a front portion adapted for attachment to a raU, the front portion spaced from, and extending substantially parafli& to the rear panel and having ends that are separated by a distance tat is greater than the width of the front face of the post, and a pair of web sections interconnecting the front pprtiqh and the rear panel, one of the pair extending from each of the ends of the front portion to a corresponding one of the ends of the rear panel, each web section including a first web anda second web, wherein the first webs extend inwardly towards each other nd away from the rail at an angle to the rail of less than 45 degrees wherein the second webs extend from the inward ends of the first webs to the ends of the rear panel, tile second webs being longer than the first webs and adjoiling the ends of the rear panel at acute angles of more than 45 degrees.

12 A roadside parapot comprising a plurality of posts supporting a rail, wherein at least oe of the posts supports the rail by ay of a hr.ack& having the form of a continuous sh?et of metal bØnt into a hape, which, when rnouhted to the post and supporting the rail, has a uniform horizontal croas-ection including paiallel front and Ii rear paneJs for attaching to the rail and post respectively and interconnectEng &des, wherein the shape of the cmsssection provides a first deformation mode of the bracket in the event of an impact to the rail exceedng a first impact level, and a second mode of deformation of the bracket in the event of an impact exceeding a second, higher impact leveL 13 1 he parapet of claim 12 further comprIsing one or more addit'onaf rails mounteo to the posts abOve said raiL 14. The parapet of claim 13 wherein said rail, Supported oh said bracket extend.s a greater distance from, the post towards the road than the additional rails.15. A bracket substantially as hereinbefore described with refcrende to the accompanying drawings. 1.516. A parapet subtantaIly as. hereinbefore described with reference tb the accompanying drawings.