Rod-reinforced cushion beam
A rod-reinforced cushion beam includes a rigid frame having a spaced of main rod members and a longitudinally paced plurality of connecting elements; and a plastic body encapsulating substantially solidly filling the frame. At least some of the transverse elements are shear panels. A preferred embodiment has least 90 percent by weight of the plastic body in a main polymeric component of linear low density polyethylene, and an additive component that does not contain filler material. Also disclosed is a method for forming a rod-reinforced cushion beam.
This application is a continuation of application Ser. No. 10/346,204, filed on Jan. 15, 2003, now U.S. Publication No. US-2004-0074202-A1, published Apr. 22, 2004, which was a continuation-in-part application of application Ser. No. 10/278,754, filed on Oct. 22, 2002, now U.S. Publication No. US-2004-0074180-A1, published Apr. 22, 2004.
BACKGROUNDThe present invention relates to elongated structural members such as pilings, columns, wales, planks, and beams, particularly for used in marine environments, and methods for making such members.
Concrete, steel, and wood are conventionally used for pilings, telephone poles, beams and the like. However, each of these materials has disadvantages. Concrete and steel pilings are heavy and awkward to maneuver. Neither concrete nor steel pilings make good fender pilings because neither is “forgiving” when impacted. Under impact steel bends and buckles and concrete shatters. Both concrete and steel pilings are expensive to repair. Furthermore, steel, either standing alone or as a reinforcement in porous concrete, is subject to corrosion.
Wood pilings, planks, and beams are plagued by wear and tear and, particularly in marine environments such as in piers and ship moorings, are attacked by wood-boring marine organisms. Wood pilings, wales and planks are typically treated with creosote, but even this material can be ineffective against modern marine borers. These marine borers can only be stopped by wrapping the wood pilings in plastic coverings. However, these plastic coverings cannot withstand much wear and tear, especially abrasion from normal vessel contact. So in addition to a thin plastic wrap, wooden fender piles and planks often require thick plastic wrappings, which are expensive to put in place, being also subject to separation.
Composite pilings are also known, being disclosed for example in U.S. Pat. No. 5,180,531 to Borzakian, that document being incorporated herein by this reference. The '531 patent discloses a plastic pipe having an inner pipe core or mandrel being 6 inches or less in diameter, and a substantially homogenous coating being at least two inches thick. The thick plastic coating provides the bulk of the mechanical strength, being formulated with a desired combination of flexibility, brittleness, and impact resistance for use as pilings including fender pilings of docks, telephone poles, light standards, etc.
U.S. Pat. No. 5,766,711 to Barmakian, which is incorporated herein by this reference, discloses a composite camel structure including a pipe mandrel and a thermally bonded plastic cushion surrounding the mandrel. A mold having the mandrel centered therein is filled with molten plastic, the plastic being cooled and solidified by feeding water into the mandrel for progressively solidifying the cushion member along mandrel for producing a thermal bond without excessive tensile strain in the plastic material, thereby to achieve a substantially unbroken outside surface.
U.S. Pat. No. 6,244,014 to Barmakian, which is incorporated herein by this reference, discloses a composite piling having a welded cage including a circular array of parallel spaced main rod members that are welded about a helically formed secondary rod member, the cage being encapsulated in a plastic body.
U.S. Pat. No. 6,412,431 to Barmakian et al., which is also incorporated herein by this reference, discloses a composite fender having a cage frame encapsulated in a plastic body, the cage frame having an attachment structure connected to plural spaced apart locations of the frame.
Notwithstanding the above, it is believed that there is a need for further improvements in structural components to be used as beams in moorings, piers, and the like that are contemplated to be used in marine environments, that such components have high bending strength and high resistance to impact loading, and that they have long life, are easily installed, environmentally sound, and durable in use.
SUMMARYThe present invention meets this need by providing a reinforced cushion beam of high bending strength, being particularly suitable for a variety of marine applications. In one aspect of the invention, an a composite beam includes a frame having plural longitudinal main rod members at least three of which are spaced in different directions relative to a longitudinal axis of the frame, and a plurality of transverse elements each rigidly connecting a spaced pair of the main rod members, at least three of the main rod members being connected to at least two others of the main rod members by at least some of the transverse elements; and a resilient plastic body encapsulating the frame and having a nominal cross-sectional area of at least 50 square inches. As used herein, the term “nominal cross-sectional area” means overall (inclusive of the frame) cross-sectional area when the cross-sectional area of the body member is uniform, and average cross-sectional area when the cross-sectional area of the body member is non-uniform, such as tapering. The plastic body can form an elongate cushion surface, the cage frame being spaced from the cushion surface by preferably not less than 10 percent of an overall thickness of the beam between the cushion surface and an opposite surface of the beam.
At least some of the transverse elements are shear panels. The shear panels can include respective laterally spaced first and second sets of longitudinally spaced shear panels, the panels of each set joining a pair of the main rod members. The sets of shear panels can be connected between respective first and second pairs of the main rod members. The main rod members can include respective third and fourth pairs of the main rod members, the first set of shear panels also being connected between the third pair of main rod members opposite the rod members of the first pair, the second set also being connected between the fourth pair of main rod members opposite the rod members of the second pair. Also, or alternatively, at least some of the shear panels can have openings and/or notches formed therein, the body having portions external to the cage frame being integrally joined through the openings and/or notches with portions of the body within the frame for enhanced structural integrity of the body.
Preferably, the main rod members and the transverse elements form a cage truss, wherein the term “cage-truss” means a rigid structure having a spaced array of elements in plural planes, the elements being strained primarily in tension and compression in response to bending and shear loading of the structure as a whole.
The main rod members and the transverse rod segments are each preferably spaced at least 0.5 inch within an outside contour of the plastic body for resistance to penetration by abrasion.
The main rod members are preferably selected from the group consisting of formed steel reinforcing bars, formed nickel alloy reinforcing bars, fiberglass reinforcing bars, and carbon fiber reinforcing bars, and at least some of the transverse elements can be selected from the group consisting of formed steel reinforcing bars, formed nickel alloy reinforcing bars, fiberglass reinforcing bars, carbon fiber reinforcing bars, plastic dowels, wooden dowels, steel plates, and fiberglass panels.
The main rod members can have a nominal diameter of between approximately 2 percent and approximately 6 percent of a nominal outside circumference of the plastic body. As used herein, the term “nominal outside circumference” of the plastic body means the overall circumference when the cross-sectional area of the body member is uniform, and average circumference when the cross-sectional area of the body member is non-uniform, such as tapering.
Preferably the plastic body sealingly surrounds the cage frame, having a thickness of not less than approximately 4 percent of the outside circumference of the plastic body over each of the main rod members and the transverse elements. The outside circumference of the plastic body can be approximately 48 inches, the diameter of the main rod members being approximately 1.25 inch. The plastic body can be rectangular or square in cross-section.
The plastic body preferably substantially fills the space occupied by the cage frame. The plastic body can consist of a main polymeric component and an additive component, the main polymeric component consisting of low-density polyethylene of which at least 60 percent is linear low density polyethylene, the additive component including an effective amount of an ultraviolet inhibitor.
Preferably the composite beam also includes an attachment structure defining attachment elements that are connected to plural spaced locations of the frame. Also, a plurality of the composite beams can be assembled to stationary structure to form an installed fender assembly.
In another aspect of the invention, a method for forming a composite beam includes:
-
- (a) providing a plurality of elongate main rod members;
- (b) providing a plurality of transverse elements;
- (c) rigidly securing opposite portions of each of the transverse elements between a laterally spaced pair of the main rod members such that each of at least three of the main rod members have pluralities of the transverse rod segments laterally projecting in at least two directions diverging from the main rod members to form a cage frame; and
- (d) encapsulating the cage frame in a plastic body.
The rigidly securing is preferably further such that at least some of the transverse elements are rod members oriented diagonally for loading the main rod members and the transverse elements that are in planes of the diagonally oriented rod segments primarily in tension and compression in response to bending and shear loading of the resulting cage truss. The securing can be by welding and/or by forming reinforced joints of epoxy resin. The rigidly securing can also, or in the alternative, be of shear panels forming at least some of the transverse elements, the main rod members being strained primarily in tension and compression in response to bending and shear loading of the resulting cage truss.
In a further aspect, a method for forming a composite beam includes:
-
- (a) rigidly securing a spaced plurality of main rod members to opposite edge regions of a first longitudinally spaced array of shear panels to form a first frame portion;
- (b) rigidly securing a spaced plurality of main rod members to opposite edge regions of a second longitudinally spaced array of shear panels to form a second truss;
- (c) locating the first and second trusses in laterally spaced relation;
- (d) rigidly securing a longitudinal array of lateral elements between the first and second trusses to form a cage frame; and
- (e) encapsulating the bonded cage frame in a plastic body.
The encapsulating can include:
-
- (a) providing an injection mold having an elongate cylindrical cavity;
- (b) loading the mold with the cage frame;
- (c) centering the welded cage frame within the mold;
- (d) injecting a polymeric composition into the mold thereby covering the cage frame; and
- (e) cooling the mold to form the structural plastic member.
Preferably the injecting includes formulating the polymeric composition to consist of low density polyethylene, at least 60 percent of the polymeric composition being linear low-density polyethylene for resisting cracking of the material. The method can also include bonding a plurality of fastener attachments to the cage frame.
DRAWINGSThese and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where:
The present invention provides a novel reinforced plastic cushion beam that is particularly effective as a sheathing plank, wale, or other structural element of a wharf facility. With reference to
The cage truss 12 includes a plurality of longitudinal main rod members 16 that are rigidly interconnected by transverse elements 17 that can include a multiplicity of transverse rod segments 18, opposite end portions of each segment 18 being connected between a pair of the main rod segments 16. As best shown in
In another aspect, the cage truss 12 includes a spaced pair of generally planar truss units 26 that are connected in generally parallel-spaced relation by the tie rod segments 24. In one preferred form, the cage truss 12 is a weldment of steel reinforcing bars having ribbed contours as indicated in
As shown in
An important feature of the present invention is a formulation of polymeric material that is suitable for encapsulating the cage truss 12 and that does not form voids and cracks due to tensile thermal strains being generated during solidification. This problem is exacerbated by the absence of a tubular mandrel that can receive cooling water as disclosed in the camel structure of the above-referenced '711 patent. It has been discovered that a particularly suitable composition for forming the plastic body 14 as an uninterrupted covering of the cage truss 12 is a main first quantity of low density polyethylene of which at least 60 percent and preferably 65 percent is linear low-density polyethylene (LLDPE), the balance being regular low-density polyethylene (LDPE), and a process additive second quantity including an effective amount of UV inhibitor, the composition not having any significant volume of filler material such as calcium carbonate. Preferably, the first quantity is at least 90 percent of the total volume of the plastic body 14, approximately 5 percent of the total volume being a mixture of coloring, foaming agent, and UV inhibitor. Preferably the composition is substantially free (not more than 5 percent) of high density polyethylene.
Thus the composition of the cushion member 14 has polymeric elements being preferably exclusively polyethylene as described above (substantially all being of low-density and mainly linear low-density), together with process additives as described below. As used herein, the term “process additive” means a substance for enhancing the properties of the polymeric elements, and does not include filler material such as calcium carbonate. The composition preferably contains a process additive which can be a foaming or blowing agent in an amount of up to about 0.9% by weight to insure than when the plastic body 14 is made by extruding the plastic composition into a mold, the mold is completely filled. The foaming agent can be a chemical blowing agent such as azodicarbonamide. A suitable chemical blowing agent is available from Uniroyal of Middlebury, Conn., under the trade name Celogen AZ 130.
Other process additives of the composition can include a coupling agent, preferably a silane, for improved bonding between the plastic body 14 and the cage truss 12.
The plastic composition can also include a fungicide, typically in an amount of about 0.25% by weight, and an emulsifier, in an amount of from about 0.1% to 0.3% by weight. The use of emulsifier improves surface appearance of the product.
The composition can also contain a carbon black, generally a furnace black, as a colorant, to improve the physical properties, and as a UV stabilizer. The amount of carbon black used is generally about 2.5% by weight.
A mold apparatus (not shown) for encapsulating the cage truss 12 to form the plastic body 14 of the cushion beam 10 includes a mold assembly and a conventional extruder press, including one or more flanged tubular mold segments as further described in the above-referenced '014 patent, but with the cross-sectional shape of the mold segments conforming to the cross-sectional shape of the body 14, with appropriate allowances for shrinkage as further described in the '014 patent.
As further described in the '014 patent, the cage truss 12 centered within a main cavity of the mold assembly, being supported by a plurality of projections 20, and/or by fasteners temporarily engaging one or more of the fastener attachments 30, or by centering screws as disclosed in the above-referenced '711 patent. Alternative mold construction is also described in the above-referenced '431 patent.
With further reference to
Next, the material of the plastic body 14 is fed into the main cavity in an inject body step 110. Then in a cooling step 112, the mold assembly with its contents is submerged in cooling water for solidifying the material of the plastic body 14, after which the assembly 42 is removed from the water (step 114), the mold is opened (step 116), and the substantially complete cushion beam 10 is withdrawn (step 118). Further details of this process are described in the above-referenced '014 and '431 patents.
With further reference to
With further reference to
With further reference to
In some military based naval applications, it is undesirable for a marine-exposed structure to be electro-magnetically sensitive. In such applications the cage truss 12 can be formed with non-magnetic materials, such as nickel reinforcing bar (formed of a corrosion-resistant steel alloy), which is available from MMFX Steel Corp. of America, Charlotte, N.C. Another suitable material is carbon-reinforced plastic bar, available from Aero Space Composite Products of San Leandro, Calif. The cage truss 12 can also be developed by using fiberglass reinforcing rods, with reinforced epoxy joints at points of contact between the main rods 12 and the various transverse rod segments 18 and/or diagonal rod segments 20. Additional suitable materials include Nylon Reinforcement, available from McMasters Co. of Los Angeles, Calif., plastic dowels, also available from McMasters, and wooden dowels, which are available from typical lumber yards.
With further reference to
With further reference to
In the exemplary configuration of
With particular reference to
The cushion beam 10 (as well as the alternatively configured beams 10′, 10″, 60, 60′, and 60″) of the present invention is immune to marine borer attack, and thus requires no further protection, such as creosote or plastic sheathing, being practically maintenance free. The cushion beam 10 is abrasion resistant, and thus has excellent effectiveness as a marine fender plank without any added protective covering.
The composite cushion beam 10 is chemically inert, so it can last indefinitely. It does not react with sea water, is corrosion free, is substantially immune to the effects of light, is not bothered by most petroleum products, and is not subject to dry rot. Because it can be made with recycled plastic, it is an environmentally sound investment.
Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, the main rods 16 can be formed having a flattened or elongate cross-section that is preferably oriented to facilitate forming the connections with the transverse rod elements 18. Therefore, the sprit and scope of the appended claims should not be necessarily be limited to the description of the preferred versions contained herein.
Claims
1. A composite beam comprising:
- (a) a frame comprising: (i) a plurality of longitudinal main rod members, at least three of the main rod members being spaced laterally in different corresponding directions relative to a longitudinal axis of the frame; and (ii) a plurality of transverse elements, each transverse element being rigidly connected between a spaced pair of the main rod members, at least three of the main rod members being connected to at least two others of the main rod members by at least some of the transverse elements, wherein at least some of the transverse elements are shear panels; and
- (b) a resilient plastic body member encapsulating the frame, the plastic body having a nominal cross-sectional area of at least 50 square inches.
2. The composite beam of claim 1, wherein the plastic body forms an elongate cushion surface, the beam having an overall thickness between the cushion surface and an opposite surface of the beam, the cushion surface being spaced from the frame by not less than 10 percent of the overall thickness.
3. The composite beam of claim 1, wherein the shear panels comprise laterally spaced first and second sets of longitudinally spaced shear panels, the panels of each set being bonded between a pair of the main rod members.
4. The composite beam of claim 3, wherein the first set of shear panels is connected between a first pair of the main rod members and the second set of shear panels is connected between a second pair of the main rod members.
5. The composite beam of claim 4, wherein the plurality of main rod members includes respective third and fourth pairs of the main rod members, the first set of shear panels being further connected between the third pair of main rod members opposite the rod members of the first pair, the second set of shear panels being further connected between the fourth pair of main rod members opposite the rod members of the second pair.
6. The composite beam of claim 1, wherein at least some of the shear panels have openings and/or notches formed therein, the body member having portions external to the cage frame integrally joined through the openings and/or notches with portions of the body member within the frame for enhanced structural integrity of the body member.
7. The composite beam of claim 1, wherein the main rod members and the transverse elements are each spaced at least 0.5 inch within an outside contour of the plastic body.
8. The composite beam of claim 1, wherein the main rod members are selected from the group consisting of formed steel reinforcing bars, formed nickel alloy reinforcing bars, fiberglass reinforcing bars, and carbon fiber reinforcing bars.
9. The composite beam of claim 8, wherein at least some of the transverse elements are selected from the group consisting of formed steel reinforcing bars, formed nickel alloy reinforcing bars, fiberglass reinforcing bars, carbon fiber reinforcing bars, plastic dowels, wooden dowels, steel plates, and fiberglass panels.
10. The composite beam of claim 1, wherein the main rod members have a nominal diameter of between approximately 2 percent and approximately 6 percent of a nominal outside circumference of the plastic body.
11. The composite beam of claim 10, wherein the plastic body sealingly surrounds the cage frame, having a thickness over each of the main rod members and the transverse elements being not less than approximately 4 percent of the nominal outside circumference of the plastic body.
12. The composite beam of claim 10, wherein the outside circumference of the plastic body is approximately 48 inches, and the diameter of the main rod members is approximately 1¼ inch.
13. The composite beam of claim 10, wherein the plastic body is rectangular in cross-section.
14. The composite beam of claim 13, wherein the plastic body is square in cross section.
15. The composite beam of claim 1, wherein the plastic body substantially fills the space occupied by the frame.
16. The composite beam of claim 1, wherein the plastic body consists of a main polymeric component and an additive component, the main polymeric component consisting of low-density polyethylene of which at least 60 percent is linear low density polyethylene, the additive component including an effective amount of an ultraviolet inhibitor.
17. The composite beam of claim 1, further comprising an attachment structure defining a spaced plurality of attachment elements connected to plural spaced apart locations of the frame.
18. An installed fender assembly comprising a plurality of composite beams according to claim 1.
19. A method for forming a composite beam, comprising the steps of:
- (a) providing a plurality of elongate main rod members;
- (b) providing a plurality of transverse elements;
- (c) rigidly securing opposite portions of each of the transverse elements between a laterally spaced pair of the main rod members such that at least three of the main rod members have pluralities of the transverse elements projecting therefrom in at least two directions having components perpendicular to the respective main rod members to form a cage frame,
- wherein the step of rigidly securing is such that at least some of the transverse elements are shear panels so that the main rod members are strained primarily in tension and compression in response to bending and shear loading of the resulting cage truss; and
- (d) encapsulating the cage frame in a plastic body.
20. The method of claim 19, wherein at least some of the securing is by welding.
21. The method of claim 19, wherein at least some of the securing is by forming joints of reinforced epoxy resin.
22. A method for forming a composite beam, comprising the steps of:
- (a) rigidly securing a spaced plurality of main rod members to opposite edge regions of a first longitudinally spaced array of shear panels to form a first frame portion;
- (b) rigidly securing a spaced plurality of main rod members to opposite edge regions of a second longitudinally spaced array of shear panels to form a second frame portion;
- (c) locating respective portions of the first and second frame portions in laterally spaced relation;
- (d) rigidly securing a longitudinal array of transverse elements between the first and second frame portions to form a cage frame; and
- (e) encapsulating the cage frame in a plastic body.
23. The method of claim 22, wherein the step of encapsulating comprises:
- (a) providing an injection mold having an elongate cylindrical cavity;
- (b) loading the mold with the welded cage frame;
- (c) centering the welded cage frame within the mold;
- (d) injecting a polymeric composition into the mold thereby covering the cage frame; and
- (e) cooling the mold to form the structural plastic member.
24. The method of claim 23, wherein the injecting comprises formulating the polymeric composition to consist of low density polyethylene, at least 60 percent of the polymeric composition being linear low-density polyethylene.
25. The method of claim 22, further comprising bonding a plurality of fastener attachments to the cage frame prior to the injecting.
26. The composite beam of claim 1, wherein the shear panels comprise laterally spaced first and second shear panels, each panel having an extended length, being bonded between a pair of the main rod members, and having notches and/or openings therein for clearing outer and inner portions of the plastic body.
27. The composite beam of claim 26, wherein the shear panels each extend substantially the full length of the cage frame.
28. The composite beam of claim 26, wherein the first shear panel is connected between a first pair of the main rod members and the second shear panel is connected between a second pair of the main rod members.
29. The composite beam of claim 28, wherein the plurality of main rod members includes respective third and fourth pairs of the main rod members, the first shear panel being further connected between the third pair of main rod members opposite the rod members of the first pair, the second shear panel being further connected between the fourth pair of main rod members opposite the rod members of the second pair.
30. A composite beam comprising:
- (a) a frame comprising: (i) a plurality of longitudinal main rod members, at least three of the main rod members being spaced laterally in different corresponding directions relative to a longitudinal axis of the frame; and (ii) a plurality of transverse elements, each transverse element being rigidly connected between a spaced pair of the main rod members, at least three of the main rod members being connected to at least two others of the main rod members by at least some of the transverse elements, wherein at least some of the transverse elements are shear panels; and
- (b) a resilient plastic body member encapsulating the frame.
32. The composite beam of claim 1, wherein at least some of the shear panels have openings and/or notches formed therein.
33. The composite beam of claim 34, wherein at least some of the shear panels have openings and/or notches formed therein.
34. The composite beam of claim 1, wherein the shear panels comprise laterally spaced first and second shear panels, each panel having an extended length, being bonded between a pair of the main rod members, and having notches and/or openings therein.
35. The composite beam of claim 35, wherein the shear panels comprise laterally spaced first and second shear panels, each panel having an extended length, being bonded between a pair of the main rod members, and having notches and/or openings therein.
Type: Application
Filed: Feb 16, 2005
Publication Date: Nov 17, 2005
Inventors: Andrew Barmakian (Alta Loma, CA), Bruce Barmakian (Upland, CA)
Application Number: 11/061,965