EP1077446A2

EP1077446A2 - Modular-type noise-insulating acoustic barrier and related manufacturing method

Info

Publication number: EP1077446A2
Application number: EP00115389A
Authority: EP
Inventors: Francesco Baroglio
Original assignee: SISTEMA BARRIERE STRADALI Srl
Current assignee: SISTEMA BARRIERE STRADALI S.R.L.
Priority date: 1999-08-16
Filing date: 2000-07-17
Publication date: 2001-02-21
Also published as: ITPN990068A1; IT1311708B1; ITPN990068A0; EP1077446A3

Abstract

Noise-insulating acoustic barrier formed by panels (10) comprising a mass of sound-absorbing material (17) arranged between two C-shaped profile sections (16) that are inserted between the flanges of I-shaped risers (11).

Pairs of fretted plates (14) enclose said panels on their front and rear sides and have their edges joined to each other by means of an alternate overlapping pattern.

The barrier is easy to manufacture directly on the site of installation.

Description

The present invention relates to a metal, modular-type noise-insulating or noise-insulating/sound-absorbing acoustic barrier, which is particularly suitable for use in applications aimed at opposing noise pollution effects generated by road and railway traffic, as well as the manufacturing method thereof.
The physiological damages imparted to human beings by the exposure to noise-polluted environments , in particular to the noise generated by road and railway traffic, are generally well-known.
In order to attenuate both these dangerous noise levels and the effects thereof, various systems are currently used, which range from proper actions taken as far as the road pavement itself is concerned (draining pavements) through to the most diffused system consisting in installing sound-deadening, ie. acoustic shields along the side edges of the traffic ways. These sound-deadening shields, by acting as an obstacle to the diffusion of the sound waves, carry a sustainable acoustic climate over to the receiving environment. In fact, each time that a sound wave meets with a solid obstacle, a part of the energy thereof is reflected by the obstacle, a part penetrates into the obstacle itself, where it is converted into mechanical vibrations that may possibly generate new sound waves, while the remaining energy passes around the obstacle, thereby perturbing the acoustic field to some extent. Finally, behind the obstacle there is a zone in which the sound pressure is reduced (acoustic shadow zone). This is the effect that is actually used for designing acoustic shields.
These noise-deadening shields are generally made up by panels manufactured out of either traditional materials, such as wood, cement, clay, glass, metal, or materials having special sound-absorbing properties, such as rock wool, polyurethane, polypropylene or polyester fibres and the like, which are associated to appropriate containment and support structures.
Panels of the latter type are generally preferable from both a technical and an economic point of view. The modules that are currently used to build up the sound-deadening barriers are essentially in the form of boxes formed by two parallel sheet-metal plates, which are spaced from and joined to each other in such a manner as to create a hollow space therebetween that is then filled with sound-absorbing material.
In order to form the acoustic shield, the upper and lower ends of the panels are shaped with a conjugate male-female profile, respectively, so as to allow for a heightwise coupling by means of a mechanical fitting-in joints. Furthermore, the panels are inserted in the bearing structure of the acoustic shield, which is generally comprised of risers of the HE type, or the like, that are anchored in appropriate foundations at a constant centre-to-centre distance (usually 3 meters).
These solutions, however, are such as to favour the passage of sound energy through the coupling zones of the panels, as well as in correspondence of the panel-support riser joints. This brings about a reduction in the sound-deadening or noise-insulating effectiveness of the acoustic shields, to the detriment of the sound-dampening performance thereof.
It therefore is a main purpose of the present invention to provide a modular-type noise-insulating or noise-insulating/sound-absorbing barrier, particularly suited for use in applications aimed at opposing noise pollution effects generated by road and railway traffic, which ensures a maximum extent of insulation and absorption of sound energy thanks to the uninterrupted and sealed construction of the shield.
According to the present invention, the acoustic barrier shall further enable any possible expansion of the materials, as they may be possibly caused by abrupt or large ambient-temperature variations that may occur under practical use conditions, to be effectively compensated for.
The method for manufacturing the innovatory acoustic barrier of the above cited kind is much simpler and, above all, it can be carried out directly on the installation site of the same barrier.
According to the present invention, these aims are reached in a modular-type noise-insulating or noise-insulating/sound-deadening acoustic barrier formed substantially by panels constituted by a mass of sound-deadening material arranged between two substantially C-shaped profile sections that are inserted between the flanges of two successive risers. Each panel is enclosed on both its front and rear sides by pairs of parallel longitudinal plates, which are attached to the free ends of the corresponding C-shaped profile sections, whereas the side, upper and lower edges of the same plates overlap each other, thereby fully covering the risers externally, in such a manner as to create a continuous structure also heightwise.
The features and advantages of the present invention will anyway be more readily and clearly understood from the description that is given below by way of non-limiting example with reference to the accompanying drawings, in which

Figure 1 is a front elevational view of a portion of acoustic barrier according to the present invention;
Figure 2 is a cross-sectional elevational view of the acoustic barrier shown in Figure 1;
Figure 3 is a longitudinal-section plan view of the acoustic barrier shown in Figure 1; and
Figure 4 is a longitudinal-section plan view of a detail of the acoustic barrier shown in Figure 1.

A road barrier according to the present invention is shown in the accompanying drawings, and in particular in Figure 1, to be formed essentially of a plurality of panels 10 that are in an aligned arrangement relative to each other and supported by risers 11. These risers 11 are normally constituted by profile bars having a cross-section in the shape of an I or double T. Each such riser 11 is connected, for instance by a welded joint, to a base plate 12 (Figure 2), which is fastened to the ground by means of stay-bolts 13 constituted by steel rods.
The barrier features outwardly two parallel and continuous surfaces, ie. a front one and a rear one, which are formed by pairs of plates 14 that have in an advantageous manner a cross-section shaped to a fret-like pattern. These plates 14 extend longitudinally between two successive risers and the side edges 15 of contiguous plates overlap each other in correspondence of the same risers (Figures 3 and 4). The plates 14 may extend vertically over the whole height of each panel, but in a preferred manner they are made according to a configuration in which they are subdivided into a plurality of metal sheets that are aligned vertically with their edges mutually overlapping in an alternate manner. Usually, the metal sheets constituting the front surface (noise generation side) of the panel are provided with perforations, whereas the rear ones have a solid surface.
Profile bars having substantially a C-shaped section are inserted vertically between the flanges of each riser 11. The concavity of each such C-shaped profile section is arranged to oppose the concavity of the corresponding C-shaped profile section inserted in the next riser 11. This arrangement makes it possible for a mass of sound-absorbing material 17, such as glass wool or the like, to be inserted between two such successive and mutually opposing profile sections 16.
In an advantageous manner, the profile sections 16 are inserted between the flanges of the risers 11, while leaving a certain distance with respect to the central rib of the same risers.
The plates 14 are then fastened to the free ends of the corresponding profile sections 16, for instance by means of self-threading screws.
The panels are completed by closing them on top by the application of profile sections 18 in the shape of a C or a reverse U.
The solution consisting in overlapping both the side vertical edges and the longitudinal horizontal edges of the plates 14 enables the main aim of the present invention to be reached, which in fact calls for a continuous and sealed acoustic shield to be created, ie. an acoustic shield that is free of undesired acoustic bridges, voids or gaps (seams, joints) that would impair the performance of the shield itself by lowering the noise insulating and sound absorbing efficiency thereof.
The assembly of the profile sections 16 with a certain clearance or slack with respect to the risers 11 furthermore enables the barrier to compensate for any thermal expansion or shrinkage that may occur under practical use conditions, which thing obviously represents an additional advantage of the described solution. The plates 14, which enclose the panels 10 externally, are in fact solely fastened to the respective profile sections 16 that are capable of moving longitudinally between the flanges of the risers 11. As already set forth earlier in this description, the plates 14 of contiguous panels have on the contrary their edges overlapping respectively, with the possibility of a relative displacement thereof.
In an improved variant of the barrier according to the present invention, when the distance between two successive risers 11 is of a considerable extent, for example 3 meters or even more, the arrangement of an additional C-shaped profile section 20 is provided, which is inserted in an intermediate position between the two risers 11 in view of stiffening the plates 14 to which it is fastened (see Figures 1 and 3).
As far as the manufacturing method is concerned, the barrier according to the present invention offers the practical advantage of it being capable of being directly assembled on the site of installation, ie. without any need arising for the panels to be pre-assembled at the factory in view of a subsequent final assembly thereof at the building yard. In fact, all structural component parts (risers, plates, profile sections, etc.) are of the elementary type and can be assembled with the use of extremely simple means in an extremely simple manner. Upon having fixed the risers 11 to the ground, the profile sections 16 are inserted between the flanges of the same risers. The rear plates 14 are then applied against the risers 11, while overlapping the side end portions of contiguous plates and fastening them to the free ends of the corresponding profile sections 16.
Thereafter, the masses of sound-absorbing material are 17 are inserted between the C-shaped profile sections 16, and the panels 10 are then sealed by the application of the front plates 14 against the risers 11, wherein the side end portions of contiguous plates are allowed to mutually overlap, under attachment thereof to the free ends of the corresponding C-shaped profile sections 16. The panels are finally closed on their top side through the application of the profile sections 18.
The described solution refers to a sound-absorbing barrier that is built directly on a road embankment. It is however appreciated that the same barrier may also be added to an already existing and installed road barrier, for example such a barrier of the New Jersey type. In this case, the sound-absorbing barrier will be installed by attaching it to the upper edge of the existing barrier under utilization of common-type fastening means, such as screws or bolts.
It will of course be further appreciated that the above described barrier may be the subject of a number of further modifications or variants without departing from the scope of the present invention.

Claims

Method for manufacturing modular-type noise-insulating barriers, which are formed of metal panels (10) filled with sound-absorbing material (17), such as glass wool or the like, and are sustained and connected by means of risers (11) that have a cross-section in the shape of an I, or a double T, and are fixed to the ground, characterized in that the barrier is manufactured by building the panels (10) through following operational phases: insertion of a vertical profile section (16) having a cross-section in the shape of substantially a C between the flanges of each such riser (11) in such a manner as to ensure that the concavity of a C-shaped profile section opposes, ie. faces the concavity of the C-shaped profile section inserted in the preceding or the successive riser; application of parallel plates (14) on to the rear sides of the risers (11) by letting the side end portions (15) of contiguous plates lap over each other, and fastening of the plates (14) to the free ends of the corresponding C-shaped profile sections; insertion of a mass of sound-absorbing material (17) in the concavities of the mutually facing C-shaped profile sections; application of parallel plates (14) on to the front sides of the risers (11) by letting the side end portions (15) of contiguous plates lap over each other, and fastening of the plates (14) to the free ends of the corresponding C-shaped profile sections; sealing of the panels (10) on top by means of profile sections (18) generally in the shape of a C or a reverse U.
Method according to claim 1, characterized in that the plates (14) applied on to the risers (11) are formed by a plurality of longitudinal metal sheets having a section in the shape of a Greek fret, which are aligned vertically by mutually overlapping and attaching the edges of successive metal sheets according to an alternate pattern.
Method according to claim 1 or 2, characterized in that the concave portion of the C-shaped profile sections (16) is inserted between the flanges of the respective riser (11) at a distance from the central rib of the same riser.
Method according to any of the claims 1 to 3, characterized in that a further C-shaped profile section (20) is inserted in an intermediate position between two successive risers (11) as a stiffening means for the metal sheets forming a panel (10).
Modular-type noise-insulating barrier, formed of metal panels (10) that are filled with sound-absorbing material (17), such as glass wool or the like, are sustained and connected by means of risers (11) having a cross-section in the shape of an I, or a double T, and are fixed to the ground characterized in that each such panel (10) is constituted by a mass of sound-absorbing material (17) arranged between two profile sections (16) having a section in the shape of substantially a C, which are inserted between the flanges of two successive risers (11), the panel being closed on the front and the rear side by pairs of longitudinal parallel plates (14) that are fastened to the free ends of the corresponding C-shaped profile sections, while the side, upper and lower edges of the plates are mutually overlapping, thereby fully covering the risers externally, so as to create a continuous structure also heightwise.
Noise-insulating barrier according to claim 5, characterized in that the plates (14) applied on to the risers are formed by a plurality of metal sheets with a fret-like section, which are aligned vertically, with the edges thereof overlapping alternately.
Noise-insulating barrier according to claim 5 or 6, characterized in that the C-shaped profile sections (16) are inserted in the corresponding cavities of the risers (11) with a clearance or slack in the longitudinal direction.
Noise-insulating barrier according to any of the preceding claims 5 to 7, characterized in that the plates (14) enclosing each panel are stiffened by the insertion of a further C-shaped profile section (20) in an intermediate position between the two respective risers (11).