AU712499B2 - Acoustic barrier module - Google Patents

Description

I f Regulation 32

AUSTRALIA

Patents Act 1952 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

r r Name of Applicant: BHP STEEL (JLA) PTY. LTD.

ACN: 000 011 058 600 Bourke Street Melbourne 3000 Victoria, Australia Actual Inventor(s): Address for Service: Invention Title: DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

Acoustic Barrier Module Details of Associated Provisional Application No.: PN2192/95 Filed 5 April, 1995 The following statement is a full description of this invention, including the best method of performing it known to us: -1- Q:\OPER\GCP\50547.C 13/9/99 -2- ACOUSTIC BARRIER MODULE This invention relates generally to acoustic barriers and is of particular but not exclusive interest in relation to modular outdoor acoustic barriers for main roads, freeways and the like.

Various approaches are currently used in efforts to reduce the sound carried from freeways, arterial roads and the like to adjacent residential areas and nearby buildings. Apart from earth mounds and the long-term approach of mass tree planting, it is known to erect extended structural barriers close to the edge of the freeway or road. It is desirable to use materials which are sound-absorbent as well as sound-reflective. Existing systems tend to be heavy and •..cumbersome, requiring the assistance of cranes to place them in position. Larger scale barriers can only be built by stacking the individual modules. Somewhat lighter modules defined by a hollow shell are susceptible to damage by impact or the weather.

It is an object of the invention to provide an acoustic barrier module which is effective yet robust, and readily adaptable to interlocking with similar modules to form larger scale barrier structures. It is a further object of the invention, at least in preferred embodiments, to provide an acoustic barrier module which is able to be manipulated and positioned without the assistance of cranes.

a *0 The invention provides, in one aspect, an acoustic barrier module which includes a shell formed of two or more layers of sheet metal, one or both of which are ribbed to provide sufficient structural strength to resist deformation by wind forces on the module without additional frame members and wherein the ribs are of substantial extent laterally of the sheet so as to define cavities in which sound-reflective and/or sound absorbent media are located.

In another aspect, the invention provides an acoustic barrier module which includes a shell of sheet metal which is substantially less wide than it is long and/or high, and which shell defines complementary upper and lower rims for respectively engaging the lower and upper rims of similar acoustic barrier modules wherein the shell is formed of two or more layers of sheet metal, one or both of which is ribbed to provide sufficient structure strength to resist 13/9/99 Xi-i-i-~ Q:\OPER\GCP\50547.C 13/9/99 -3deformation by wind forces, and wherein the ribs are of substantial extent laterally of the sheet so as to define cavities in which sound-reflective and/or sound absorbent media are located.

Preferably, the module further includes a sound-reflective or sound-barrier medium such as, for example, fibreboard, especially a fibre cement board. A suitable sound-absorbent medium would be sound-absorbent fibrous material, for example retained in bags within the chamber.

The aforementioned ribs may be of substantial extent laterally of the sheet so as to define cavities for housing the sound-absorbent material. In a preferred construction, only one of the layers of sheet metal has such ribs and exhibits a broad W cross-section at the side which is intended in use to face the source of the sound.

°o.0 In either aspect, the sheet metal is preferably shallow ribbed for additional strength. The 15 sheet metal may be perforated in some way at the side which is intended in use to face the source of the sound, for example by an array of slots or other apertures. With such apertures sound-absorbent medium, a barrier formed of several of the modules can serve as a sound *ooe *absorbing barrier for little additional cost relative to the simple reflective array.

The upper and lower rims of the module preferably carry complementary interengaging to means, for example, a rib structure at one longitudinal edge and a complementary groove "structure at the other. These structures are conveniently formed in sheet metal which may be integral with or separate from but attached to sheet metal defining front and rear faces of the module.

The module is preferably of panel configuration in which the shell is defined by separate shallow ribbed metal sheets at front and rear.

Multiple similar acoustic barrier modules in accordance with the invention may be assembled into an acoustic barrier, in the vertical direction by interengaging the complementary upper and lower rims of respective modules and horizontally by engaging the ends of the modules with M0 P:\OPER\GaFPN2192.CAJ' 4/4,96 -4two or more spaced posts. These posts are preferably themselves formed in sheet metal, for example C-section channels with return lips. In one arrangement, the C-section channels are arranged in back-to-back pairs to form double C-posts. In another arrangement, used to stagger adjacent segments of the barrier, a post of generally Z-section might be utilised.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a partially exploded view of an acoustic barrier formed from acoustic barrier modules in accordance with the invention, and viewed towards the side which would be facing the source of noise, for example a freeway or other main road; 0* Figures 2 and 3 are enlarged fragmentary views of portions of the barrier shown in Figure 1; 15 Figure 4 is a view of a similar modular barrier from the other or rear side, but differing from Figures 1 to 3 in the configuration of the supporting posts; Figure 5 is an enlarged fragmentary view of a portion of the barrier shown in Figure 4; Figure 6 is a cross-section of one of the acoustic barrier modules in Figures 1 and 4; Figure 7 depicts the profiles of the male and female joints forming the complementary upper and lower rims of each module; and Figure 8 is a sketch of a modified form of acoustic barrier module.

The acoustic barrier 10 in part illustrated in Figures 1 to 4 might typically be located along the edge of a freeway or other main road to reduce the traffic noise heard by adjacent buildings and residential areas. The barrier is formed in successive segments 12 each comprising a vertical stack of acoustic barrier modules 20 and each supported at its vertical end edges by ii P:\OPER\Ga<jN92.CAP 414,6 respective posts 14 of a generally Z cross-section configuration. Typically, these posts 14 would be set in concrete footings 16 and the underlying space between the protruding portions of the footings filled by fibre cement boards 18.

Each acoustic barrier module 20 (Figure 6) comprises a shell 21 of sheet metal defining a chamber 22. Shell 21 is made up of a rear panel 24 with strengthening longitudinal shallow ribs 24a, and a front W-section panel 26 defining a pair of parallel large trapezoidal section ribs 28 whose flat tops are in turn provided with longitudinal shallow ribs 26a similar to ribs 24a. Shell 21 is substantially less wide than it is long and indeed the shell is substantially elongate end-to-end and parallel to ribs 24a,26a,28.

Sheet metal panels 24,26 include uppermost and lowermost flat opposed lips 24b,26b which .o are separated by a solid sound-barrier panel 30, which may suitably be of a bitumen filled fibrous material, for example bitumen-filled caneite. The troughs of panel 24 between ribs 15 24a abut the rear face of panel 30, thereby strengthening the assembly, and the top and bottom edges of the assembly are capped by respective complementary male and female joint strips 34,36. The profiles of these strips, which are also formed in sheet metal, are detailed in Figure eoo 7.

The male joint strip 34 defines an upstanding continuous tapered rib 38 with a smoothly curved tip 39 and spaced depending flanges 40a,40b which are offset outwardly from rib 38 by shoulders 42 and are periodically spot-welded, pop-riveted or clinched onto the outer faces of lips 24b,26b. The longitudinal interface is preferably silicone bonded or otherwise sealed to minimise or prevent ingress of rain or other contaminants.

Female joint strip 36 is of curved W cross-section defining a longitudinally extending tapered centre groove 45 and outer flanges 47a,47b which are similarly spot-welded, pop-riveted or clinched onto the outer faces of bottom lips 24b,26b.

I

P:\OPER\Ga'\PN2192.cAJ -4(4,96 -6- Joint strips 34,36 are complementary so that adjacent similar modules may be firmly vertically interengaged in a tongue and groove joint. It will be appreciated that joint strips 34,36 complete the shell 21 and define complementary upper and lower rims of the module for respectively engaging the lower and upper rims of similar modules.

Caneite panel 30 serves as a sound-reflective medium retained within chamber 22. The cavities within large ribs 28 form further portions of chamber 22 and these may house a sound-absorbent material such as extended masses 47 of rockwool encased in polyethylene bags 48.

The module 20 is completed by end caps 50 (Figures 1 to 3) comprising shallow rectangular sheet metal channels which snugly receive the ends of the module so that, in each case, one 52 of the flanges of the channel engages the ribs 24a of panel 24, and is secured to some of them, while the other flange 53 engages and is fixed to the ribs 26a of W-section panel 26.

The configuration of Z posts 14 is best seen in Figure 2. The posts are formed by overlapping and securing together (eg by screws) a pair of oppositely facing similar lengths 54 of sheet metal of lipped L cross-section. The barrier segments 12 are positioned in a staggered arrangement so that the return lips 55 of the posts 14 respectively engage the large ribs 28 at the front of one segment and the shallow ribs 24a at the rear of the next adjacent segment. The structure is stabilised by abutting the web portions of end cap strips 50 against the main web of the post and welding or clinching the two together.

It will be understood that the W-section panels 26 normally face towards the source of the noise and it is preferred that the sound-absorbent media be disposed in front of the sound reflecting media with respect to the source.

Figure 4 is a view of a portion of a sound barrier from the rear but also exhibits a different form of posts 14'. This form of post (best seen in Figure 5) is formed from two similar Csection sheet metal channels 54' fastened together back-to-back and may be used for either P:\OPER\0CPPN2192CAP 4/496 -7aligned (as illustrated) or staggered barrier segments.

Figure 8 is a sketch of a modified form of acoustic barrier module 20" in which the soundabsorbent properties of the module are enhanced by forming openings along the top and underneath sections of each of the trapezoidal section ribs 28". These openings may be discontinuous staggered arrays of slots 60 formed by simply pressing in longitudinal tabs 62 of the metal. It is thought that the area occupied by the slots in the areas where they are provided might be of the order of 10 to 30% of the total area, for example about The sheet metal utilised in the modules 20 is preferably of a gauge in the range 0.42 to 0.6 millimetres. The steel gauge and the size of the module is preferably chosen so that the •module is of sufficient strength and stability but is also of such a weight that it is capable of being readily carried and manhandled into position by no more than two persons. It will be appreciated that the barrier of the form shown in Figure 1 or 4 can then be erected without the 15 assistance of cranes or other heavy equipment but indeed may be constructed by two people 0000 working together. A satisfactory and typical module might be of four metres in length and 600 millimetres in height so that the illustrated barrier segment 12 is three metres in height. It is preferred that the weight of the module does not exceed 0. 20 The described arrangement has been advanced merely by way of explanation and many 0 modifications may be made thereto without departing from the spirit and scope of the invention which includes every novel feature and combination of novel features herein disclosed.

Claims (18)

1. An acoustic barrier module which includes a shell formed of two or more layers of sheet metal, one or both of which are ribbed to provide sufficient structural strength to resist deformation by wind forces on the module without additional frame members and wherein the ribs are of substantial extent laterally of the sheet so as to define cavities in which sound- reflective and/or sound absorbent media are located.

2. An acoustic barrier module which includes a shell of sheet metal which is substantially less wide than it is long and/or high, and which shell defines complementary upper and lower •rims for respectively engaging the lower and upper rims of similar acoustic barrier modules and wherein the shell is formed of two or more layers of sheet metal, one or both of which is ribbed to provide sufficient structure strength to resist deformation by wind forces, and :wherein the ribs are of substantial extent laterally of the sheet so as to define cavities in which sound-reflective and/or sound absorbent media are located. ,1

3. A module as claimed in claim 1 or 2 wherein the media comprises fibre cement board, ••fibrous material, rockwool and/or bitumen-filled caneite.

4. A module as claimed in claim 3 wherein the media comprises elongate masses of sound absorbent material located in respective cavities.

A module as claimed in claim 4 wherein one of the layers of sheet metal has a W- shaped cross-section.

6. A module as claimed in claim 5 wherein the other layer is generally planar.

7. A module as claimed in claim 6 including a panel of sound reflective material is within the shell and is located adjacent to said other layer. Q:\OPER\GCP\50547C 5/3/99 -9-

8. A module as claimed in claim 7, wherein bags of rock wool are located in said cavities.

9. A module as claimed in any preceding claim wherein said layers of sheet material include shallow ribs.

A module as claimed in any preceding claim wherein at least one of the layers of sheet material is perforated or slotted.

11. A module as claimed in any preceding claim including interlocking means for interlocking modules together.

12. A module as claimed in claim 11 wherein the interlocking means comprises a rib structure at one longitudinal edge and a complementary groove structure at the other.

13. A module as claimed in claim 12 wherein the rib structure is connected to upper longitudinal edges of the layers of sheet metal and the groove structure is connected to lower °longitudinal edges of the layers of sheet metal.

14. A module as claimed in any preceding claim including side end strips connected to side edges of the layers of sheet metal. U. Ut An acoustic barrier comprising: a plurality of posts; and a plurality of modules as claimed in any one of claims 1 to 14 mounted between the ports.

Ur S b

16. A barrier as claimed in claim 15 wherein a plurality of modules are vertically stacked between adjacent posts. Q:\OPER\GCP\50547.C 5/3/99

17. A barrier as claimed in claim 16 as limited to claim 12 or 13 wherein the rib structures of lower modules are received within the groove structures of the module above and adjacent thereto.

18. A barrier as claimed in any one of claims 15 to 17 as limited to claim 14 wherein the posts have channels and the side end strips are received within said channels. Dated this 5th day of March, 1999 BHP STEEL (JLA) PTY. LTD. By its Patent Attorneys DAVIES COLLISON CAVE a. *r S e, 9. *r S w 0@0 0*0