BACKGROUND OF THE INVENTION In general, it is conventionally known to resiliently mount a wall or ceiling in order to isolate sound or attenuate transmission therethrough.

U. S. Patent No. 3,445,975 to Nelsson discloses a partition in which first and second lath panels are held against a metallic stud, channel, or furring member by a clip fastener. One portion of the stud, channel, or furring member is cantilevered away from the portion at which the lath panels are clipped thereto. According to Nelsson, this permits the free portion of the stud, channel, or furring member to flex as the lath panels mechanically respond to sound waves incident thereon. The remainder of the structure dampens this surface movement, reducing sound transmission to the opposite surface of the partition.

U. S. Patent No. 3,324,615 to Zinn discloses a construction member having a plurality of laterally extending supporting tabs by which wallboard segments are resiliently mounted.

U. S. Patent No. 3,046,620 to Tvorik et al. discloses a ceiling hanger member whereby a furring strip (to which a ceiling member is attached) is resiliently attached to a joist, such that the weight of the furring strip and ceiling member resiliently separates the furring strip from the joist.

Another known method of sound attenuation is to build a wall frame in which studs are laterally staggered relative to a toe plate and head plate. Therefore, alternate studs are used to mount wall board on respective sides of the frame so that a given stud is spaced away from one of wall boards.

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Unfortunately, the foregoing conventional methods of noise attenuation are problematic in that they generally move away from basic construction methods and thereby increase complexity and cost. For example, they require additional parts (such as Tvorik et al. and Nelsson) or specially made parts (such as the channel member with specially formed support tabs, as in Zinn). The staggered stud arrangement necessarily results in a thicker wall partition which reduces the area of the room whose walls are framed in this manner, and increases the cost of the toe and head plates.

In addition, nail fasteners generally cannot be used with metal members, thereby undesirably restricting available construction methods.

In addition to the devices for sound attenuation described hereinabove, a wood I- beam is commercially available (for example, under the brand name"BCI Advantage" from Boise Cascade Corporation) that comprises a pair of wood members with a rigid wooden panel extending therebetween. However, because the wooden panel is essentially non-resilient, this I-beam offers little or no sound attenuation benefit.

SUMMARY OF THE INVENTION The present invention is therefore broadly directed to a structural system utilizing a combination of construction members and board members to define structural surfaces like walls, ceilings, floors, etc. while providing useful degrees of sound attenuation or sound transmission prevention.

In part, the present invention is directed to beam-type construction members that rely on resilient flexibility in order to attenuate sound transmission therethrough. The construction members according to the present invention advantageously closely conform to conventional building members (especially with respect to dimensional considerations) in order to minimize or eliminate the need for any special handling or the like in use. The present invention contemplates construction beam members sized comparably to conventional wood beams (for example, 2 in x 4 in or 2 in x 6 in (5.08 cm x 10.16 cm or 5.08 cm x 15.24 cm)). A beam member according to the present invention comprises a pair of spaced of lateral members having a resilient web extending therebetween. The web is preferably relatively stiff, but permits a slight flexure between the lateral members.

The lateral members are preferably made from an easily workable material such as wood.

In combination with the above-described beam members, the present invention contemplates a board member mounted on the beam members according to the present

invention. In particular, a board member is provided comprising first and second relatively rigid layers, the first and second layers having a visco-elastic material layer interposed therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in detail hereinbelow, with reference to the drawings appended hereto, in which: Figure 1 is a partial perspective view of an end of a construction beam according to the present invention; Figure 2 is an end view of a construction beam member according to the present invention; Figure 3 is a plan view of a construction beam member according to a different embodiment of the present invention; Figure 4 is a perspective view of an example of a linkage for linking lateral members in a construction beam member according to the present invention; Figure 5 is a partial perspective view of a framework for mounting board members (especially the aforementioned multilayer board members) or the like, utilizing construction beam members according to the present invention; Figure 6 is a partial perspective view of a construction beam member according to yet another embodiment of the present invention; Figure 7 is a plan view of a construction beam member according to the embodiment of the present invention shown in Figure 6; Figure 8 is a plan view of a variant of the construction beam member shown in Figure 7; Figure 9 is a partial cross-sectional view illustrating a constrained layer structure of a board member used with the present invention; Figure 10 is a cross-sectional view illustrating the formation of a lap joint between two board members having a constrained layer construction according to the present invention; and Figures 11 (a) and 11 (b) illustrate board members according to the present invention for forming a ship lap joint and a plain lap joint, respectively.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE PRESENT INVENTION The term"construction beam member"may be interchanged freely with"beam," "beam member,"and"construction member"herein and still be within the meaning and scope of the disclosure set forth.

Figures 1 and 2 illustrate a portion of a beam 100 according to the present invention. In general, beam 100 comprises lateral members 102 and 104 with a web 106 spanning therebetween.

Lateral members 102,104 are generally squared in cross-sectional profile and have at least the same thickness y (see Figure 2). Moreover, lateral beams 102,104 are preferably identical so that each has the same width, proportionately spaced with web 106 therebetween so as to present an overall beam width x. Lateral members 102,104 are preferably (but not necessarily) identical in shape so as to facilitate manufacture of beam 100 from one source of stock.

Accordingly, beam 100 presents a cross section having a major dimension x and minor dimension y corresponding to any standard beam size (for example, 2 in x 4 in or 2 in x 6 in (5.08 cm x 10.16 cm or 5.08 cm x 15.24 cm), and so on, without limitation).

According to the present invention, lateral members 102,104 are elongate rigid members. Accordingly, a variety of suitably rigid materials could be used. However, lateral members 102,104 are preferably (but not exclusively) made from wood, (in part, in keeping with an intent of the present invention to present a construction member very similar to those conventionally used in the art). Wood is also desirable because it can be worked, generally, in more ways than comparable metal members (for example, it can be easily cut, driven with nails or screws, etc.). Not only can continuous lumber be used, but composite materials, such as plywood or wood particle board can be used. In addition, finger jointed wood members can be used according to the present invention. A plastic material reinforced with glass fibers may also be used in accordance with the present invention.

Web 106 is made from a relatively rigid material that has some flexibility. If web 106 is relatively too flexible, lateral members 102,104 have too much relative freedom of movement and beam 100 is no longer, overall, a rigid member. If web 106 is relatively too stiff, then the benefits of sound isolation/attenuation are lost. Generally, web 106 may

be made from any suitably stiff and resilient material, including (without limitation) rubber, asphalt, plastic or other resilient polymeric material.

In one example of the present invention, web 106 is made from galvanized 22 gauge steel. As seen in Figure 4, web 106 includes edge portions 106a and an intermediate portion 106b. Edge portions 106a are embedded in lateral members 102, 104, and intermediate portion 106b extends obliquely between lateral members 102,104.

However, intermediate portion 106b may, most generally, extend between lateral members 102,104 in any orientation so long as flexure between lateral members 102,104 is relatively easy (compared to, for example, an intermediate portion extending straight across the gap between lateral members 102,104, which does not readily flex).

It is noted that the use of galvanized steel as described here may offer additional ancillary benefits, such as improved fire safety protection.

Edge portions 106a are embedded in lateral members 102,104 in any conventional manner. One possible method (not illustrated) is to form grooves in lateral members 102, 104 that are wider than the thickness of edge portions 106a. Once edge portions 106a are suitably disposed in the respective grooves, additional strips of material (such as wood) are pressed into the remaining space in the grooves, such that edge portions 106a are wedged into place and retained in the grooves.

Web 106 may extend continuously substantially the entire length of lateral members 102,104. However, when beams 100 are used in construction, it is useful to provide a plurality of spaced apart webs 106, such that piping, wiring and the like can be passed through the openings between webs 106 (see Figure 3).

Whether one or a plurality of webs 106 are provided, it is specifically contemplated that beams 100 are provided in standardized lengths (for example, 8 ft (2.44 meter) as seen in Figure 3 and can be cut down as required.

As mentioned above, it is an important feature of the present invention to provide a construction member that can be used like conventional construction beams.

Accordingly, Figure 5 is a partial perspective view of a frame (as might be used for walls in a building).

As seen in Figure 5, beams 100a, 100b are mounted as studs on a laterally extending beam (that is, a head plate or toe plate) 100c. (Another laterally extending beam (not shown) is provided at the other end of beams 100a, 100b.) The structure of each of beams 100a-100c is in accordance with the description of the present invention

hereinabove, and will not be repeated here. Attention is drawn to the manner in which lateral members 102a and 102b and 104a and 104b are mounted with respect to lateral members 102c and 104c, respectively, with nails, screws or any other conventional fasteners (not shown here). Accordingly, it can be appreciated that one side of the frame (that is, lateral members 102a-102c) are resiliently separated by way of respective webs 106', 106", and 106"'from the other side of the frame (that is, lateral members 104a- 104c). Accordingly, sound impinging on a board member mounted on one side of the frame is attenuated upon transmission to the other side of the frame because of the dissipative resilience of webs 106', 106", and 106"'.

Furthermore, it is possible to resiliently mount a wall so that it acts like a diaphragmatic sound absorber. In particular, only one"side"of the frame assembly (for example, lateral member 104c and/or lateral members 104a, 104b) is fixed to the surrounding structure, and the other side of the frame assembly has wall board or the like mounted thereon (that is, on lateral members 102a, 102b), without attachment to the surrounding structure. The wall is therefore mounted on the"free"or"floating"side of the studs.

In order to enhance the effect of decoupling the one side of the wall frame from the surrounding structure, it is desirable to provide a soft gasket (made from, for example, foam rubber) between the lateral beam 100c and the surrounding structure (that is, the ceiling and/or floor). This promotes relatively free movement of the one side of the frame that is not fixed to the surrounding building structure.

To further enhance the effect of decoupling the wall from the surrounding structure, it is preferable to provide flexible joint material at junctions between wall board segments, including at corners of rooms. Therefore the wall surface is visually continuous, but physically decoupled, in order to take advantage of the resultant sound attenuation effects.

Also, it is very desirable to provide additional sound and/or thermal insulation in the spaces defined by the studs and end plates. Such insulation can be of any conventional type, including blown, rolled or batting, foam board, etc. The addition of such insulation enhances sound attenuation effects resulting from the present invention.

To enhance the sound insulation effect of the frame illustrated in Figure 5 even further, it is desirable to use a board member having a multilayer structure as seen in Figure 9 (described further below).

Although a frame for a wall is illustrated in Figure 5 and correspondingly described hereinabove, the structural concepts used therein are applicable to ceiling and even floor surface construction.

Figures 6 and 7 are a partial perspective view and a partial plan view, respectively, of beam 200, in accordance with another embodiment of the present invention.

The design concept underlying beam 200 is fundamentally similar to that of beam 100. Like before, lateral members 202 and 204 are provided, and are resiliently spaced apart from each other by web 206. Unlike web 106 in beam 100, however, web 206 is not embedded in lateral members 202,204. Instead, web 206 is fixed (by any conventional means, such as nails, as shown in Figures 6 and 7) relative to opposite faces of lateral members 202,204 along the major dimension of the beam cross section.

As in the first embodiment, a plurality of spaced apart webs 206 may be provided along the length of beam 200 (see, for example, Figure 7).

Web 206 is preferably made from a material that is slightly more flexible than that used for web 106, such as 24 gauge galvanized steel.

Initial comparative testing has been undertaken comparing the sound attenuation characteristics of conventional construction members versus beam 100 and beam 200.

Initial results indicate that beam 100 has greater than expected attenuation characteristics, and that beam 200 should have even better attenuation performance than beam 100. This latter effect is thought to be caused by the shape and orientation of web 206, which more easily permits a normal compression between lateral members 202,204.

In addition, as a variation of the embodiment illustrated in Figure 7, the plurality of webs are alternately arranged so that the portion of the webs extending obliquely thereacross alternates (thereby crossing each other, as seen from an end of beam 200) (see Figure 8). In Figure 8, beam 300 comprises lateral beams 302 and 304, and includes a plurality of first webs 306a which are spaced from and alternate with a plurality of second webs 306b. Accordingly, respective intermediate portions of webs 306a and 306b criss- cross as seen from an end of beam 300.

Inasmuch as sound that one seeks to attenuate or isolate is typically physically unique relative to particular environments (for example, a home theater room, a movie theater, a machine shop, a recording studio, a concert hall), it is an important feature of the present invention to provide a construction member that can be"tuned"in order to tailor its sound attenuation properties for a specific environment. In other words, a beam

according to the present invention can be specifically manufactured so that its resilient properties (in terms of, for example, spring constant) are made to correspond to a particular kind of sound (especially in terms of its frequency) so that sound attenuation can be maximized.

Such"tuning"can be accomplished by varying the thickness of web 106,206, either uniformly or variably over the entire area of web 106,206. In addition, notches, slits, or other openings can be formed in web 106,206 to control the resilience of web 106,206 in accordance with known principles of physics. In addition, suitably sized perforations or openings in a continuous web can be formed so as to create a tunable Helmholtz resonator effect between adjacent cavities defined between studs in the framework illustrated in Figure 5. By altering the number and/or size of the perforations or openings, a resultant Helmholtz resonant frequency can be controlled, at which attenuation of sound at that frequency is maximized. It should be noted that this is different from reference to a plurality of webs as shown in Figures 3,7, and 8.

It can therefore be appreciated that adjoining rooms may be constructed (for example, adjoining musical studios) such that each room can be tuned in accordance with its respective mode of use. In particular, this may be accomplished by constructed "double wall"framework, where two frames of the structure illustrated in Figure 5 are constructed face-to-face, such that the respective opposing sides of the frames are fixed to the surrounding building structure and their respective opposite sides are left free floating in the manner discussed above.

Although construction members according to the present invention have been described hereinabove for wall frames and the like, they are also contemplated for use in mounting floating ceilings which are acoustically isolated from a building structure. In addition, construction members according to the present invention may also be used in floor construction.

In particular, a construction member for mounting a floating ceiling may be used by fixing one of the lateral members to the building structure and fixing a ceiling member to the free floating lateral member (that is, the lateral member not fixed to the building structure).

Although the use of substantially identical lateral members is contemplated according to the present invention, it is expressly within the scope of the present invention to use dissimilar lateral members. For example, one of the lateral members 102,104

shown in Figure 2 may be replaced by a conventional wood I-beam of the type described above. In particular, web 106 may be embedded in one of the flange portions of the wood I-beam, in the manner disclosed above.

Although the present invention is directed primarily to construction members made from non-metallic materials, the design concepts may be of interest in the manufacture of metal studs comprising a pair of metal members with a resilient web extending therebetween in accordance with the foregoing description. In particular, a metal stud using the inventive principles disclosed herein could be made from a single piece of sheet metal, formed into shape.

In general, the present invention is directed to the use of standard wall and ceiling materials, such as (without limitation) drywall and acoustical tiles, respectively, in conjunction with the resilient construction member (and various structural combinations thereof) described hereinabove.

However, sound attenuation effects are enhanced by the use of board members having a constrained layer (multilayer) constituent structure. In general, as seen in Figure 9, a board member 400 has a"sandwich"layer structure, including, for example, respective rigid layers 402, with a visco-elastic material layer 404 interposed therebetween, as seen in Figure 9. The rigid layers 402 are desirably conventional, such as layers of dry wall.

The use of the visco-elastic material layer 404 generally provides a sound energy loss mechanism between one side of the board member 400 from the other, thereby diminishing the structural sound transmission path therethrough. Visco-elastic material layer 404 essentially serves as a slip plane. In addition, the visco-elastic qualities of layer 404 provide a damping effect in accordance with the shear modulus and loss factor of the visco-elastic material used.

It is noted that other configurations also provide a loss mechanism having desirable sound attenuation effects. These include, without limitation, providing abutting rigid layers, such that energy is dissipated by dry friction between the facing surfaces of the rigid layers. This effect may be enhanced by increasing the surface roughness of one or both of the rigid layers.

Alternate multilayer board structures may be provided. For example, each rigid layer 402 may further comprise a plurality of rigid sublayers (not shown), such that first

and second pluralities of rigid sublayers have a visco-elastic material layer interposed therebetween.

Furthermore, a plurality of rigid sublayers may be alternated with a plurality of visco-elastic material layers (not shown here).

Moreover, it is desirable to provide such multilayer board members with dimensions (especially thickness) the same as or almost the same as corresponding "standard"board members. Accordingly, the board member 400 may comprise dry wall layers 402 which are each, for example, 0.25 in (0.76 cm) thick, and a visco-elastic material layer 304 which is very thin (for example, 0.10 in (0.254 cm) thick). The board member 400 therefore is comparable in thickness to a"standard"board member that is 0.625 inches thick (that is, 0.675 in (1.587 cm) thick). The board member 400 may instead have an overall thickness of, for example, 0.5 inches. Standard major dimensions are also contemplated, such as 4 ft x 8 ft, 4 ft x 10 ft, 4 ft x 12 ft (1.22 m x 2.44 m, 1.22 m x 3.05 m, 1.22 m x 3.66m), etc.

The visco-elastic material may be any material conforming to conventional construction requirements (for example, building and safety codes, etc.). The attenuating effect of the board member 400 may be varied, at least in part, in accordance with the shear modulus and loss factor of the visco-elastic material used. The visco-elastic material may include, without limitation, an asphalt material of suitable shear modulus and loss factor.

The attenuating effect of the board member 400 may additionally be varied in correspondence with respective thicknesses of rigid layers 402.

It is also recognized, within the scope of the present invention as described herein, that the manner in which a board member (both a conventional unilayer board member and the above-described multilayer board member using a visco-elastic material layer) is attached to the underlying framework must be considered so as to not detract from the sound attenuation benefits of the resilient construction members and/or the multilayer board members. In particular, it is currently believed that fastening/mounting methods which act to increase the rigidity or stiffness of the system will cause a deterioration in sound attenuation characteristics.

While it is generally contemplated that pre-fabricated board members 400 are provided (that is, board members in which the respective layers are all arranged), board members according to the present invention may be constructed on-site or"in the field."

For example, respective rigid layers 402 may be arranged and fixed together on-site by a layer of the visco-elastic material 404. In this regard, it is noted that the use of asphalt, for example, as the visco-elastic material offers certain adhesive characteristics that help hold together the respective rigid layers 402.

Further to this idea, it is within the scope of the present invention to provide rigid layers 402a (see Figures 10,11 (a), and ll (b)) which are offset from one another, so as to provide a lap joint (as is known in the art) interconnectable with other board members 400 with similarly offset rigid layers 402a. The arrow in Figure 10 illustrates this interconnection generally. It is noted that the offset creates one stepped region 406 having the visco-elastic material 404a formed thereon, and a corresponding stepped region 408 without the visco-elastic material formed thereon. The exposed region having the visco- elastic material 404a (especially asphalt) thereon serves to act as an adhesive relative to corresponding region 408 because of its inherent tackiness. It will be appreciated that it is usually not desirable to provide the visco-elastic material on both region 406 and 408 because the combined thicknesses of visco-elastic material can alter the overall thickness of the board members or cause loss of planarity.

In accordance with the foregoing, it may be convenient to provide a pelable release backing 410 (for example, silicone coated paper) over the exposed portion of visco-elastic material. Therefore, the backing can be peeled off when respective board members are assembled onsite.

Figure 11 (a) illustrates board members 402 (a) which are offset in two perpendicular dimensions, so as to provide what is commonly known as a ship lap joint.

Figure 11 (b) illustrates board members 402 (a) which are offset only in one direction.

It is particularly useful, according to the present invention, to use multilayer board members as described hereinabove with the"double wall"framework discussed above.

Experimental testing of a conventional wood stud wall (that is, not using the resilient construction member described hereinabove) with a constrained layer board member like board member 400 resulted in a sound damping rating (quantified by Sound Transmission Class (STC) numbers) of 48, which compares favorably with an STC of 38 for a standard 0.50 in (1.27 cm) dry wall board. Accordingly, the use of the constrained layer board member 400 with the resilient construction beam members described herein is expected to provide an even higher STC rating (that is, even greater sound attenuation).

The present invention being thusly described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.