STRUCTURAL MEMBER HAVING A METAL SHELL REINFORCED BY A REINFORCING PLATE

Abstract: A structural member comprises an elongated hollow case including at least two thin metal shells, each side end of the shells having a flange along its entire length and the flanges facing each other to form the hollow case, at least one of reinforcing end piece to be engaged with an end portion of the case, and a filler moulded into the case. A reinforcing plate is attached by using an adhesive such as epoxy resin to an inner surface of each of the thin metal shells to improve a tensile strength of the structural member. In addition, the reinforcing plate is provided with at least one cut-out portion and an appropriate number of projections formed on a side of the cut-out portion. The adhesive filling the cut-out portions functions as an additional means for improving the tensile strength of the structural member.

Description: STRUCTURAL MEMBER HAVING A METAL SHELL REINFORCED BY A REINFORCING PLATE TECHNICAL FIELD OF THE INVENTION The present invention relates to a structural member with an elongated hollow thin metal shell filled with a filler; and, more particularly, to a novel structural member provided with a reinforcing plate attached to an inner wall of the elongated hollow thin metal shell to improve the tensile strength thereof. BACKGROUND ART In general, a structural member such as a pillar, column, post, pole, beam and the like is made of lumber, concrete, metal or their composites according to its intended use . In particular, a structural member made of concrete has been widely used in the construction field because of its high compressive strength and economy. Also, it has a further advantage that it can be easily made in various shapes by designing diverse molds. However, such concrete columns and posts are not normally suitable for use in decorative articles due to their rough surface characteristics and non-aesthetic appearance. Accordingly, additional finishing elements made of lumber and/or metal plates are required to refurbish the crude surfaces of the concrete members in order to employ them for sophisticated purposes. Consequently, hollow metal structural members made of, e.g., aluminum, aluminum alloys, stainless steel, zinc plated steel, special steel, copper or copper alloys are increasingly employed in various structural members such as supporting columns, connecting bars, ornamental poles and the like because of their appealing appearance, high corrosive resistance and easy workability. In such hollow metal members, a relatively greater thickness is required to withstand a given load, thereby entailing a high material/manufacturing cost. Therefore, there have been attempts made to reduce the thickness of such a hollow metal structure by way of forming a section of the structure in a bent or inwardly grooved shape, to thereby increase the bending strength and the moment of inertia of the metal structure. However, the manufacturing cost of such metal member still remains relatively high because the formation of a particular shape in the metal member adds further manufacturing steps. In addition, reducing the thickness of the metal member in an effort to reduce the cost can backfire as it makes the structure vulnerable to an external impact . Accordingly, various structural members have been developed with the specific purpose of improving their tensile and compressive strength. There is disclosed in U.S. Patent Nos . 5,263,297 and 5,457,929 issued to the present applicant, a structural member adapted to be used in combination with a base, the structural member comprising an elongated hollow thin metal shell, a reinforcing end piece engaged in an end portion of the shell, the reinforcing end piece having a through-hole, and a filler moulded into the hollow thin shell and the through-hole of the reinforcing end piece. The reinforcing end pieces disclosed in the above patents may be embedded in the concrete filler, thereby preventing both ends of the shell from being deformed in the process of injecting concrete mortar into the shell and preventing both end portions of the structural member from rupturing or breaking during the transportation or construction thereof. One of the major shortcomings of the prior structural members is that they are essentially capable of supporting small to medium loads only. In other words, in situations where they are required to support large loads, especially large tensile loads such as bridge balustrades, building, erection and the like, they cannot be used. DISCLOSURE OF THE INVENTION It is, therefore, a primary object of the present invention to provide a structural member with a thin metal shell capable of supporting even a large tensile load. The above and other objects of the present invention are accomplished by providing a structural member comprising : an elongated hollow case including at least two thin metal shells, each side end of the metal shells having an inwardly bent flange along its entire length and the bent flanges facing each other to form the elongated hollow case ; a reinforcing plate attached to an inner surface of each of the metal shells; and a filler moulded into the hollow case. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings, in which: Fig. 1 shows an exploded perspective view, with a filler of concrete removed for the sake of clarity, of a structural member having a reinforcing plate in accordance with a preferred embodiment of the present invention; Fig. 2 exemplifies a perspective view for explaining stresses applied to the structural member of Fig. 1 ; Figs. 3A to 3E are perspective views for illustrating various variations of the reinforcing plate and for showing directions of the applied stresses; Fig. 4 presents a sectional view taken along I-I line in Fig. 3D; Fig. 5 demonstrates a perspective view of the reinforcing plate with cut-out portions only; Fig. 6 indicates an exploded perspective view, with a filler of concrete removed for the sake of clarity, of a structural member incorporating therein a connecting means with a reinforcing plate and a thin metal shell in accordance with a second preferred embodiment of the present invention; Fig. 7 provides a sectional view showing how the structural member shown in Fig. 6 is assembled; Fig. 8 depicts a view similar to that of Fig. 6 with a connecting means slightly different from that shown in Fig. 6; Fig. 9 represents a sectional view showing how the structural member shown in Fig. 8 is assembled; Fig. 10 offers an exploded perspective view of another reinforcing end piece of Fig. 1; Fig. 11 describes a sectional view showing the details of the structural member of Fig. 10; Fig. 12 illustrates a partially cut out perspective view of the structural member, with concrete moulded into the hollow shell of Fig. 10, employing the reinforcing end piece of Fig. 10; Fig. 13 sets forth a sectional view taken along line II-II of Fig. 12; Fig. 14 displays an exploded perspective view showing a further embodiment of the reinforcing end piece of Fig. 1; Fig. 15 gives an exploded perspective view showing a still another embodiment of the reinforcing end piece of Fig . 1 ; and Fig. 16 employs an exploded perspective, with a filler of concrete removed for the sake of clarity, of a circular structural member having a circular reinforcing plate in accordance with a third preferred embodiment of the present invention. MODES OF CARRYING OUT THE INVENTION Referring to Fig. 1, there is shown a structural member 100 in accordance with a preferred embodiment of the present invention. As shown, the structural member 100 comprises an elongated hollow case 110 having a pair of thin shells 112, a pair of reinforcing end pieces 120 inserted into both ends of the case 110, and a pair of reinforcing plates 130 attached to an inner wall of each of the elongated shells 112, respectively. The case 110 is filled with a filler 140 (Fig. 2), e.g., concrete mortar. In the structural member in accordance with an embodiment of the invention, the thin shell 112 may be made of metal such as stainless steel, aluminum, copper or their respective alloys. Each side end of the metal shells 112 along its entire length is provided with an inwardly bent flange 114 to allow the hollow case 110 to be formed by facing the flanges 114. As a result of the flanges facing each other in forming the case, ribs are formed in the case along its entire length, the ribs further increasing the contact areas between the filler 140 and the case 110. The ribs will function as the anchors for the filler 140. The reinforcing end pieces 120 are provided with a through-hole 122 through which the filler 140 is injected into the case 110, a stepped portion 124 formed around an upper portion thereof for preventing the reinforcing end pieces 120 from being excessively inserted into the case 110 and a pair of slit portions 126 formed at both sides thereof, respectively, to thereby allow the ribs of the case 110 to be slid therealong, allowing the reinforcing end pieces 120 to be tightly engaged with the case 110. The reinforcing plate 130 is made of a metal, layers of fibrous material selected from the group consisting of carbon fiber, aramid fiber and glass fiber, or a combination thereof, i.e., a combination of the metal and fiber layers. The reinforcing plate 130 is attached to the inner wall of the metal shell 112 by means of an adhesive such as epoxy resin, soldering or spot welding to improve the tensile strength of the structural member 100. Further, the reinforcing plate 130 may be further provided with a pair of projections 132 formed by inwardly bending each side end thereof along its entire length in order to increase the contact area between the reinforcing plate 130 and the filler 140. The projections 132 function as the anchor for the filler 140. When a load W is applied, as shown in Fig. 2, on the inventive structural member, the structural member is subjected to three types of stresses; a compressive stress on upper portion of the structural member as indicated by arrows A, a tensile stress on a lower portion thereof as indicated by arrows B and a shear stress on a side portion thereof as indicated by arrows C. The strength of the structural member is associated with its ability to withstand, i.e., absorb or relieve, the stresses applied thereon. The reinforcing plate 130 attached on the inner walls of the case 110 absorbs or relieves the tensile stress built in the structural member as shown in Fig. 3A. The projection 132 on each end of the reinforcing plate 130 along its length enhances the tensile and the shear strengths of the structural member 100 by functioning as the additional anchoring means for the filler as shown in Fig. 3B. Unlike the reinforcing plate 130 of Fig. 3B provided with the projections 132 on both side ends thereof along their entire length, the reinforcing plate 130 may be provided with at least one cut-out portion 131 and an appropriate number of projections 133 formed on a side of the cut-out portions 131 of the reinforcing plate 130 as shown in Figs. 3C to 3E. As best shown in Fig. 4, when the reinforcing plate 130 with cut-out portions 131 and projections 133 is attached to the metal shell 112 by means of an adhesive 138 such as epoxy resin, the cut-out portions 131 get filled with the adhesive 138, the adhesive filling the cut-out portions 131 functioning as an additional means for absorbing the tensile stress and the shear stress. The number and the location of cut-out portions 131 and the projections 133 are determined by the tensile strength desired. In addition, the reinforcing plate 130 may be simply provided with a plurality of cut-out portions 134 having any particular shape, as shown in Fig. 5, the adhesive filling the cut-out portions 134 serving to absorb the tensile stress, thereby increasing the tensile strength of the structural member 100. Referring now to Figs. 6 and 7, there is shown a structural member capable of connecting other objects thereto in accordance with a second preferred embodiment of the present invention. As shown, the structural member 200 includes an elongated hollow case 210 including at least two thin metal shells 212, each of the metal shells 212 having an aperture 216, and a reinforcing plate 230 attached to an inner surface of each of the metal shells 212 and having an aperture 234 corresponding to the aperture 216 of the each of the thin metal shells 212. Other structural members (not shown) can be connected to the inventive structural member 200 by way of an appropriate connection means 250 through the apertures 216 and 234. Each side end of the metal shells 212 along its entire length is also provided with an inwardly bent flange 214 to allow the hollow case 210 to be formed by forcing the flanges 214 to face each other. The connecting means 250 may include, for example, a threaded bolt 252 having a threaded groove 253 and fastened through the apertures 216 and 234, a nut 256 fastened to the threaded bolt 252, and a bolt 254 fastened to the threaded groove 253 to be used to connect the structural member to other objects. An end portion of the threaded bolt projecting inwardly from the reinforcing plate may further function as the anchor of the filler 140. There is shown in Figs. 8 and 9 a structural member employing another connecting means in which a connecting member 258 is provided with a threaded groove 259 to be adapted to fasten the threaded bolt 252 instead of the nut 256 as shown in Figs. 6 and 7. On the other hand, there is shown in Figs. 10 and 11 another reinforcing end piece which is similar to that of Fig. 1. As shown, the reinforcing end piece 220 includes not only the through-hole 122, the stepped portion 124 and the slit portions 126 of the reinforcing end piece 120 as shown in Fig. 1, but also includes two pairs of parallel ribs 224 inwardly extended along the respective slit portions 126, a pair of inserting holes 226, each of the holes being located at an end of each of the ribs 224, and a coupling member 170 having a cylindrical portion 172 at one end thereof to be inserted into the inserting hole 226 and a stopper portion 174 at the other end for preventing the coupling member 170 from being completely inserted into the inserting hole 226. The cylindrical portion 172 and the stopper portion 174 are provided with a threaded groove 176, respectively. A cylindrical bolt 262 is threaded into the stopper portion 174 to thereby anchor the filler 140 as shown in Fig. 13 and a bolt 260 is threaded through a bracket (not shown) mounted in a base (not shown) into the cylindrical portion 172 to thereby prevent the threaded groove 176 from being plugged during the filling of the filler 140 as shown in Fig. 12. After filling of the filler 140, the bolt 260 is removed and the threaded groove 176 can be used in connecting the structural member to other objects by using a suitable connecting means. Referring now to Figs. 14 and 15, there is shown another modified reinforcing end piece of the present invention. The reinforcing end piece 320 as shown in Fig. 14 is similar to that of Fig. 1 except that a pair of threaded- holes 326 are integrally provided at side walls of the reinforcing end piece 120 of Fig. 1, respectively, the side wall being away from a slit portion 126. The cylindrical bolt 262 and the bolt 260 of Figs. 10 and 11 are threaded to the threaded-holes 326. The reinforcing end piece 420 as shown in Fig. 15 is a combination of the same shown in Figs. 10 and 11 with the same shown in Fig. 14 except that a pair of threaded-holes 326, instead of the pair of the inserting holes 226 into which the coupling member 170 is inserted, are employed. Fig. 16 illustrates a structural member in accordance with a third embodiment of the present invention. As illustrated, this structural member 300 comprises a circular elongated hollow case 400 including three circular thin metal shells 430, a circular reinforcing plate 410 attached to an inner surface of each of the metal shells 430 by using an adhesive such as epoxy resin, soldering, and spot welding, and a pair of circular reinforcing end pieces 440 engaged with an end portion of the case 400. Each side end of the metal shells 430 along its entire length is provided with an inwardly bent flange 420 to allow the hollow case 400 to be formed by facing the flanges 420. The circular reinforcing end piece 440 is provided with three slit portions 442 to allow the bent flanges 420 of each of the metal shells 430 facing each other to be slid therealong. As described above, although the structural member of the present invention is of a rectangular shape or a circular shape, it is not limited to these shapes and may have various configurations, e.g., a pentagonal shape, a hexagonal shape, etc. Although the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that certain changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims: what is claimed is: 1. A structural member comprising: an elongated hollow case including at least two thin metal shells, each side end of the metal shells having an inwardly bent flange along its entire length and the bent flanges facing each other to form the elongated hollow case; a reinforcing plate attached to an inner surface of each of the metal shells; and a filler moulded into the hollow case. 2. The structural member according to claim 1, wherein the reinforcing plate is made of a metal, layers of a fibrous material selected from the group consisting of carbon fiber, aramid fiber and glass fiber, or a combination of the metal and the fiber layers. 3. The structural member according to claim 1, wherein the reinforcing plate is attached to the inner surface of each of the metal shells by using an adhesive such as epoxy resin, soldering, or spot welding. 4. The structural member according to claim 1, wherein the reinforcing plate is provided with a projection formed by inwardly bending each side end thereof along its entire length. 5. The structural member according to claim 1, wherein the reinforcing plate is provided with at least one cut-out portions and an appropriate number of projections formed on a side of the cut-out portions. 6. The structural member according to claim 1, wherein the reinforcing plate is provided with at least one cut-out portions. 7. The structural member according to claims 5 or 6 , wherein an adhesive fills the cut-out portions of the reinforcing plate during the process of attaching the reinforcing plate to the inner surface of the metal shells. 8. A structural member comprising: an elongate hollow case including at least two thin metal shells, each of the metal shells having at least one aperture, each side end of the metal shells having an inwardly bent flange along its entire length and the bent flanges facing each other to form the elongated hollow case; a reinforcing plate attached to an inner surface of each of the metal shells and having at least one aperture corresponding to the aperture of each of the metal shells; means for connecting the structural member to other objects through the apertures on the hollow case and the reinforcing plate; and a filler moulded into the hollow case. 9. The structural member according to claim 8, wherein the connecting means includes a threaded bolt fastened through the apertures of the hollow case and the reinforcing plate, and a nut fastened to the threaded bolt . 10. The structural member according to claim 8, wherein the connecting means includes a threaded bolt fastened through the apertures of the metal shells and the reinforcing plate, and a connecting member having a threaded groove fastened to the threaded bolt . 11. The structural member according to claims 9 or 10, wherein the connecting means further includes a threaded groove formed at the threaded bolt and a bolt fastened to the threaded groove of the threaded blot . 12. The structural member according to claim 1, further comprising at least one reinforcing end piece to be engaged with an end portion of the hollow case, the end piece having a through-hole through which the filler is moulded into the hollow case, and a pair of slit portions formed at both sides thereof to allow the bent flanges facing each other to be slid therealong. 13. The structural member according to claim 12, wherein each of the reinforcing end pieces further includes at least one pair of parallel ribs inwardly extending along the respective slit portions, a pair of inserting holes provided at ends of the ribs, and a coupling member having a cylindrical portion at one end thereof to be inserted into the inserting hole and a stopper portion at the other end thereof, the cylindrical portion and the stopper portion being provided with a threaded groove, wherein an anchoring member is threaded into the stopper portion to thereby anchor the filler. 14. The structural member according to claim 12, wherein each of the reinforcing end pieces further includes a pair of threaded-holes integrally provided at a side wall thereof, the side wall being away from the slit portion, wherein an anchoring member is threaded into each of the threaded-holes to thereby anchor the filler. 15. The structural member according to claim 12, wherein each of the reinforcing end pieces further includes two pairs of parallel ribs inwardly extended along the respective slit portions, a pair of threaded-holes provided at ends of the ribs, and a pair of threaded-holes integrally provided at side walls thereof, the side walls being away from the slit portion. 16. The structural member according to any one of claims 12 -15, further comprising a stepped portion formed around an upper periphery of the reinforcing end piece to thereby prevent the end piece form being excessively inserted into the case.

Inventors: KIM JOONG SHIK, KIM, JOONG, SHIK
Applicants: KIM JOONG SHIK, KIM, JOONG, SHIK
Application year: 1998
Main classification: E06B
IPC codes: E04B1, E04C3