SHEET METAL BEAM

Abstract: A panel of thin sheet metal is roll-formed into a beam (175) having upper and lower first edge or flange portions (181) integrally connected by a web portion (176). The first edge or flange portions (181) are reinforced by corresponding second flange portions (182) which may be separate or formed from the panel and folded back onto the corresponding first flange portion. The upper and lower flange portions may project in opposite directions from the web portion providing the beam with a Z-shaped cross-sectional configuration to facilitate close nesting of the beams in a stack, or the web portion may be disposed in the center of the flange portions to provide an "I" cross-sectional configuration. A plurality of parallel spaced stiffening ribs (177) are formed in the web portion (176), and a series of longitudinally spaced strut members (190) extend vertically between the flange portions and conform to the configuration of the web portion. The second flange portions (182) may comprise separate heavier sheet metal strips which are attached to the first flange portions (181), and the strut members (190) may be molded or cast from a flowable material.

Description: SHEET METAL BEAM Background of the Invention In the construction of a metal building, it is common to use a frame which supports parallel spaced steel beams or purlins to which corrugated sheet metal roof panels are attached. The purlins have a Z-shaped cross-sectional configuration, for example, as illus¬ trated in U. S. Patents No. 2,871 ,997, No. 3,290,845, No. 3,982,373 and No. 3.513,614. Similar Z-shaped beams are attached to the sides of the frames and a re commonly referred to as wall girts for support¬ ing the roll -formed sheet metal side wall panels. The most commonly used purlins are roll -formed from a relatively heavy gauge steel strip, such as fourteen gauge (.07 ") » an have a height of approxi¬ mately eight inches. Thus the flange portions of a purl in are integrally connected by the flat web portion, and all of the portions have a common uniform,thickness which results in a weight of approx?- mately 3.67 pounds per linear foot for an eight inch purlin. While eight inch purlins are most commonly used because of its strength/weight ratio, purlins having a greater height, such as twelve inches, are also used in view of the fact that the strength of the purlin increases as the square of the height. However, as the. flat web portion of a conventional purl in increases to provide the. purlin with a greater height, the additional- thickness of steel needed in the web portion adds little to the increased strength but substantially increases the weight of the purlin. It has also been found desirable for the flange portions - of a purlin to have a. substan ially flat outer surface to provide proper attachment of the purl ins to the metal frame and of the roof panels to the purlins by suitable fasteners. While a one-piece con- vential Z-shaped purlin may be efficiently manufactured by roll- forming, it does not provide maximum utilization of the strength of the steel and thus does not obtain the maximum streng h/weight ratio. While there have been many other types of sheet metal beams either proposed or made, none of these beams have been found satis- 5 factory for replacing the above described purlins commonly used in the construction of a metal building. Summary of the Invention The present invention is directed to an improved sheet metal beam which obtains maximum utilization of the strength of the 0 sheet metal in order to minimize the thickness or gauge of the sheet metal and to obtain a maximum strength/weight -ratio. While the beam of the invention is ideally suited for use as a purlin in the con¬ struction of a metal building, the beam of the invention may also be used in the construction of other building structures. 5 A beam constructed In accordance with the invention is also adapted to be efficiently manufactured at a significantly lower cost than the cost of manufacturing conventional metal beams or purlins, and further provides a significantly lower weight per linear foot of beam so that the cost of handling and transporting the beam Is 0 significantly reduced. While a number of desirable features and advantages of a beam constructed in accordance with the invention are apparent from the drawings, other features and advantages of the invention will be apparent from the following description and claims In reference to the drawings. 25 Brief Description of the Drawings FIG. 1 is an end view of a beam constructed In accordance with the invention and showing the assembly of conforming strut members; FIG. 2 is a fragmentary section taken generally on the 30. line 2-2 of FIG. 1; FIG. 3 is a perspective view of a strut member used in the embodiment shown in FIGS. 1 and 2; FIG. 4 is an end view of another beam embodiment forming a modification of the beam shown in FIGS. 1-3; FIG. 5 is an end view of a modified beam constructed in accordance with another embodiment of the invention; FIG. 6 is an end view of another embodiment of a purlin- type beam constructed in accordance with the invention; FIG. 7 is a fragmentary section taken generally along the 1 ine 7-7 of FIG. 6; and FIG. 8 i s an end view of another modified purlin-type beam similar to the beam shown in FIG. 6 and also constructed In accor¬ dance with the invention. Description of the Preferred Embodiments An I-beam construction is illustrated In FIGS. 1-3. In this embodiment, an elongated beam 175 includes a web portion 17 which is roll-formed from a sheet metal panel and Includes longi¬ tudinally, extending ribs 177- The panel also forms inner flange portions I78 each having a V-shaped rib. The beam 175 also includes outer flange portions or flange members 181 which are roll-formed from a heavier gauge sheet metal. Each of the outer flange members 181 includes longitudinally extending and Inwardly projecting para¬ llel edge sections or portions 182 and an intermediate rib I83 which Is secured to the adjacent inner flange portion 178 by a series of longitudinally spaced spot welds or fasteners 184. The beam 175 also includes a series of sheet metal strut members 190 (FIG. 3) which are arranged at longitudinally spaced Intervals along each side of the web portion 176 and extend vertically between the upper and lower outer flange portions or members 181. Each of the strut members 190 has a main portion with a Z-shaped cross-sectional configuration and a set of verti¬ cally spaced ear portions 192 which are trapezoid in configuration and project into and between the ribs 177 of the web portion I76 in conforming relation. The ear portions 192 have right angle tabs 194 which are secured by spot welds or fasteners 196 and 197 (FIG. 2) to the web portion 176 and to the strut members 190 on the opposite side of the web portion. Fasteners 198 secure the strut members 190 to the edge sections or portions 182 of the flange members 181. - - The use of the double strut members 190 on opposite sides of the web portion I76 enables the beam 175 to be produced with relatively wide upper and lower outer flange members 181, and it Is apparent that the strut members maintain the corrugated vertical cross-sectional configuration of the web portion 176 In addition to carrying the vertical loads between the upper and lower outer flange portions. The construction of the beam 175 also provides for flexibility in that the vertical height of the beam may be changed without requiring substantial changes in the tooling for roll-forming the sheet metal panel forming the web portion I76 and before the inner flange portions I78 are formed. FIG. 4 illustrates another I-beam 205 which Is constructed In a manner similar to the beam 175 described above in reference to FIGS. 1-3. The beam 205 Includes upper and lower outer flange portions or members 181 which are identical to the outer flange portions or members 18] shown in FIG. 1. A substantially thinner sheet metal panel is roll-formed to form a web portion 208 having longitudinally extending ribs forming a vertical corrugated cross- sectional configuration. The sheet metal panel extends to form upper and lower inner flange portions 210 each of which has two V-shaped ribs forming a trapezoid cross-sectional configuration. The inner flange portions 210 are connected by longitudinally spaced fasteners 212 to the ribs 183 within the outer flange portions 181.. ' In the embodiment shown in FIG. 4, the beam 205 includes longitudinally spaced sheet metal strut members 215 each of which has a main portion with a Z-shaped cross-sectional configuration. The outer flange of each strut member 215 Is secured by spot welds or fasteners 198 to the edges 182 of the outer flange portions 181 , * and the inner flange of eac -strut member 215 Is* secured by fasten¬ ers 217 to a web conforming member 222 having a vertical -cross- sectional configuration mating with the corrugated cross-sectional configuration of the web portion 208. As shown in FIG. 4, prefer¬ ably each-of the web conforming strut members 222 is molded from OMP metal as a die casting or from an injected plastics material so that the web conforming member 222 may be economically produced In high volume. Identical strut members 222 are used on opposite sides of the corrugated web portion 208, and fasteners 224 secure the upper and lower flange portions 210 to the inner flanges of the sheet metal strut members 215- The construction of the beam 205 also provides for producing beams of different heights withou re¬ quiring substantial additional tooling for producing each component of the beam. For example, the length or height of the Z-shaped sheet metal strut members 215 may be easily changed for changing the height of the beam 205, the outer flange portions 181 remain the same, and the height of the web portion 208 may be changed by adding or deleting another rib before the upper and lower flange portions 210 are formed, for example, on a press brake. .FIG. 5 shows a beam 235 which is constructed similar to the beam 175 described above in connection with FIG. 1. The beam 235 includes a sheet metal panel which forms a web portion 236 having longitudinally extending and vertically spaced ribs 238 forming a vertical corrugated cross-sectional configuration. The sheet metal panel extends to form upper and lower Inner flange portions 241, and upper and lower outer flange portions of members 181 are connected to the inner flange portions 241 by spot welds or fasteners 184 which extend through the ribs 183 of the flange members 181. In place of the sheet metal strut member 190, the beam 235 Includes a series of longitudinally spaced strut members 246 which are molded from a metal or plastics material. As. used herein, mold¬ ing includes die casting of a metal as well as injection molding of a plastics material. Each of the strut members 246 extends verti- ' cally between the outer flange portions or members 181 and includes portions 248 which project into the ribs 238 of the corrugated web " portion 236. Each strut member 246 is also provided with holes for receiving self-threading fasteners 251 which secure the strut, member to the web portion 236 and to the flange portions 181. While the bea 235 is Illustrated with a series of strut members 246 on only one side of the web portion 236, molded strut members may be used on both sides of the web portion 23"6 in longitudinally offset or alternating relation so that there is always convenient access for Inserting the fasteners 251 which secure the strut members to the web portion 236. Another Z-shaped purlin or beam 255 ϊs shown in FIG. 6 and Includes a thin sheet metal panel which forms a web portion 256 and upper and lower inner flange portions 258. The web portion 256 is corrugated to form vertically spaced and longitudinally extending ribs 261 each having a trapezoid cross-sectional configuration. Each of the inner flange portions 258 also has V-shaped ribs forming a trapezoid cross-sectional configuration. The beam 255 also in¬ cludes upper and lower outer flange portions or members 264 which have a thickness substantially greater than the thickness of the web portion 256. For example, the web portion 256 may be formed from 24-gauge sheet steel , and the flange portions 264 may be formed from 17-gauge sheet steel. The opposite edge portions 266 of each flange member 264 are formed or bent inwardly to provide the flange member with two V-shaped ribs forming a trapezoid cross-sectional configuration con¬ forming to the shape of the adjacent Inner flange portion 258. A series of longitudinally spaced bolts or fasteners 267 secure the corresponding upper and lower adjacent flange portions 258 and 264; Each fastener 267 may be provided with a countersunk flat head, or the flange portions may be attached by longitudinally spaced spot welds. The purlin or beam 255 also includes longitudinally spaced pairs of strut members 272 each of which is molded of a metal or plastics material and has portions 274 which project Into or between the ribs 261 of the web portion 256. Each pair of strut members 272 are secured together by self threading screws or fasteners 276 (FIG. 7) and clamp the web portion 256 between the strut members for positively maintaining' the corrugated cross-sectional configur- ation of the web portion. Another series of longitudinally spaced fasteners 276 also secure the strut members 272 to the over-lapping edge portions 266 of the outer flange members 264. While the fasteners 276 are shown with projecting head portions, the fasteners may have countersunk flat heads so that they do not project from the outer surfaces of the strut members 272. The strut members 272 may then serve as bumpers when a plurality , of beams 255 a re stacked In nesting relation. FIG. 8 Illustrates another Z-shaped purlin, or beam 285 which is constructed in a manner similar to the beam 255- The beam 285 includes a sheet metal panel which forms a web portion 286 having longI tudinal ly extending and vertically spaced ribs 288 each having a V-shaped cross-sectional configuration and thus provide the web portion 286 with another form of generally vertical corrugated cross-sectional configuration.. The sheet metal, panel also extends to form upper and lower inner flange portions 291 which are secured to outer flange portions or members 264 by longi udinally spaced fasteners 292 in the form of rivets or bolts or spot welds. In reference to the beam 255 shown in FIG. 6, the upper outer flange portion or member 264 overlaps the lower outer flange portion or member 264, whereas in the beam member 285 shown in FIG. 8, both of the upper flange portions 291 and 264 overlap both of the lower flange portions. In a manner similar to the beam 255, the beam 285 includes a series of longitudinally spaced pairs of strut members -294 which are also molded of a metal or plastics material and include portions which project * lateral ly into and be¬ t-ween the ribs 288. Each pair of strut members 294 are clamped together by fasteners (not shown) which extend through aligned holes within the strut members and the web portion 286 so that the strut members 294 positively maintain the corrugated cross-sectional con¬ figuration of the web portion. Longitudinally spaced fasteners 297 also secure each pair of strut members 294 to both of the inner and outer flange portions 291 and 2.64. From the drawings and the above description, it Is apparent that a sheet metal beam constructed in accordance wi h the present invention provides desirable features and advantages. For example, each of the beam constructions is initially formed of a relatively light gauge sheet'metal panel having a thickness less than .040 Inch and preferably about .024 inch. The sheet - metal panel Is formed in a manner which provides for utilizing the Inherent strength of the sheet metal and to obtain a maximum strength/weight ratio. As a result, a beam constructed in accor- dance with the invention significantly reduces the cost for con¬ structing a beam having a predetermined strength and thus makes more efficient use of the metal. The substantially higher strength/weight ratio of the beam also results in significantly reducing the weight of each linear foot of the beam ' from the weight of a conventional beam so that the beam of the invention may be more easily handled and more economically shipped than a conventional beam. A beam constructed in accordance with the invention also provides for flexibility in design in that the height of the web portion of the beam may be selected or Increased without sub¬ stantially increasing the weight of the beam, thereby taking advantage of the fact that the strength of the beam increases as the square of the web height. Each of the beam embodiments also provides flange portions having large flat outer surfaces which are highly desirable for attaching the beams to a frame and for attaching overlying corrugated sheet metal panels to the beams with threaded fasteners. The beam embodiments described In connection with FIGS. 1-8 provide especially desirable features. For example, the strut members used in these embodiments include portions which project laterally Into and between the ribs of the corrugated web portion and in conforming relation to the corrugations so that the corrugated shape o£.the web portion is positively maintained when the beam is loaded. As a result, the conforming strut members provide for ~ 2θ minimϊzing the ςhickness of the sheet metal panel forming the cor¬ rugated web portion. The separate upper and lower outer flange portions in these beam embodiments also provide for selecting the gauge for the outer flange portions according to the design loading on the beams. The outer flange portions- are also positively secured f to the corresponding inner flange portions and to the strut members to provide a substantially rigid beam construc ion. In the embodiments shown in FIGS. 6 and 8, the overlap of the flange portions is effective to reduce the roll -over moment and thereby improve the load carrying ability of a Z-shaped beam with only a small decrease in the nesting compactness of the beams in a stack. It Is also apparent that each of the beams may be joined end-to-end with adjacent end portions in overlapping relation. In addition, the longi udinally spacing between adjacent strut members » may be selected according to the design loads on the beam. As also disclosed in connection with FIGS. 1-8, the conforming strut members may be formed of sheet metal, die cast metal or injection molded plastics material , according to the particular use and load bearing requirements for the beam. The sheet metal strut member 190 also provides complete access for spot welding each strut member to the web portion and to the outer flange portions or for attaching rivets or other fast¬ eners. While an " I-beam is illustrated in FIG. 5, It is apparent that the construction could be used for producing C-beams, for example, .to replace conventional C-beams used In the construction of metal buildings. As another feature, the longitudinally spaced pairs of double strut members in opposing relation not only function to clamp the corrugated web portion therebetween, but also function to carry the column loading between the upper and lower flange por- ' tions. While the forms of beams herein described constitute pre¬ ferred embodiments of the invention, it Is to be understood that the invention is not limited to these precise forms of beams, and that changes may be made therein without departing from the scope and spirit of the invention, as defined In the appended claims.

Claims: The invention having been described, the following Is c1aImed: 1. An improved elongated beam adapted for use In constructing a building and having a substan ially high strength/weight ratio, said beam comprising a sheet metal panel having an upper edge k portion integrally connected to a lower edge portion by a web portion, said web portion having a plurality of vertically spaced " and longitudinally extending Integrally formed stiffening ribs providing said web portion with a " generally corrugated vertical cross-sectional con iguration, an upper flange portion and a lower flange portion adjacent the corresponding said upper and lower edge portions, means rigidly connecting said upper and lower flange portions to the corresponding said upper and lower edge portions, a plurality of longitudinally spaced strut members extending generally vertically adjacent said web portion, said strut members including means projecting laterally into said ribs, and means rigidly con¬ necting,said strut members to said web portion for positively maintaining said corrugated configuration of said web portion. 2. A beam as defined in claim 1 wherein said web portion is confined between opposing pairs of said strut members, and fasteners extending through holes within said web portion to secure each pair of strut members. 3. A beam as defined in claim 1 wherein each of said strut members Is formed of a flowable material and conforms substantially to said corrugated cross-sectional configuration of said web portion. 4. A beam as defined in claim 1 wherein said first.and second upper flange portions project laterally from said web.portion In a direction opposite to said first and second lower flange portions to provide said beam with a generally Z-shaped cross-sectional configuration. ft " άi - I 1 - 5. A beam as defined in claim 1 wherein each of said flange portions comprise longitudinally extending edge* sections Integrally connected by an intermediate section, said edge sections projecting at an angle relative to said intermediate section, and fastener means securing said upper and lower edge portions to said Inter¬ mediate sections of the corresponding said flange portions. 6. A beam as defined in claim 1 wherein each said rib within said web portion includes converging longitudinally extending wall sections,* and said laterally projecting means on said strut members conform to the shape of said converging wall sections. 7. A beam ' as defined in claim 1 wherein each said strut member comprises a main portion having a. Z-shaped cross-sectional configura¬ tion, and vertically spaced ea r portions projecting from said main portion into said ribs. 8. A beam as defined in claim 1 wherein each said strut member comprises a body of molded plastics material , and said body includes means defining holes for receiving self-threading fasteners to secure said strut members to said web portion. 9. , A beam as defined In claim 1 wherein said upper flange portion and said lower flange portion project from said web portion in opposite directions to provide said beam with a generally Z- shaped cross-sectional configuration, and said upper flange portion overlaps said lower flange portions in relation to a vertical plane extending between said flange portions. 10. A beam as defined in claim 9 wherein said upper and lower flange portions comprise formed strips of sheet metal having a thickness greater than the thickness of said panel, and said strut members a re arranged in opposing pairs with said web portion confined therebetween. 11. A beam- as defined in claim 1 wherein said strut members are arranged in longitudinally spaced opposing pairs with said web portion confined therebetween. 12. A beam as defined In cla-im 1 wherein each said strut member comprises a body of molded material. 13. A beam as defined in claim 1 wherein each of said second flange portions comprise a strip of sheet metal having a thickness greater than the thickness of said panel, each said strip includes a longitudinally extending rib spaced between generally parallel edge portions, and means securing said strut- members to said edge portions of said strip. 14. A beam as defined in claim 1 wherein each of said upper and lower edge portions has a generally trapezoid cross-sectional configuration. 15. A beam as defined In claim 1 wherein each of said strut members projects between said edge portions and said flange portions. 16. A beam as defined In claim 1 wherein said upper flange and edge portions and said lower flange and edge portions project laterally from said web portion in opposite directions to provide said beam with a generally Z-shaped cross-sectional configuration. 17- A beam as defined in claim 1 wherein each of said strut members tapers in a vertical direction, and said upper flange portion overlaps said lower flange portion.

Inventors: LOWE COLIN F, LOWE, COLIN, F.
Applicants: LOWE COLIN F, LOWE, COLIN, F.
Application year: 1983
Main classification: E04C3
IPC codes: E04C3