CA1163774A - Iso-beam and process for its manufacture from nested hollow assemblies - Google Patents
Iso-beam and process for its manufacture from nested hollow assembliesInfo
- Publication number
- CA1163774A CA1163774A CA000375901A CA375901A CA1163774A CA 1163774 A CA1163774 A CA 1163774A CA 000375901 A CA000375901 A CA 000375901A CA 375901 A CA375901 A CA 375901A CA 1163774 A CA1163774 A CA 1163774A
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- Prior art keywords
- boards
- assemblies
- accordance
- hollow
- side walls
- Prior art date
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- 230000000712 assembly Effects 0.000 title claims abstract description 34
- 238000000429 assembly Methods 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- 238000005304 joining Methods 0.000 claims abstract description 3
- 238000010276 construction Methods 0.000 claims description 3
- 238000009826 distribution Methods 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims 1
- 238000005520 cutting process Methods 0.000 claims 1
- 230000007423 decrease Effects 0.000 claims 1
- 230000003247 decreasing effect Effects 0.000 claims 1
- 238000005755 formation reaction Methods 0.000 claims 1
- 239000000463 material Substances 0.000 description 18
- 239000002023 wood Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 238000000418 atomic force spectrum Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 241000370685 Arge Species 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- -1 i.e. Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000000284 resting effect Effects 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
- E04C3/14—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members with substantially solid, i.e. unapertured, web
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Rod-Shaped Construction Members (AREA)
Abstract
ABSTRACT
A process for manufacturing a beam includes simultaneously modulating the size of the cross-section of the beam in a plurality of transverse directions in order to adapt various portions of the beam to both shear and flexional forces to which the beam is subjected. The process includes forming the beam by successively nesting a plurality of hollow, different width assemblies. Each assembly is formed by joining framework portions of the beam to side walls so as to form the hollow assemblies which are successively nestable within the next larger assembly. The beam comprises a plurality of hollow assemblies, each of which includes at least two boards and side walls connecting the boards. Each portion of the cross-section of the beam has hollow assemblies nested within one another.
A process for manufacturing a beam includes simultaneously modulating the size of the cross-section of the beam in a plurality of transverse directions in order to adapt various portions of the beam to both shear and flexional forces to which the beam is subjected. The process includes forming the beam by successively nesting a plurality of hollow, different width assemblies. Each assembly is formed by joining framework portions of the beam to side walls so as to form the hollow assemblies which are successively nestable within the next larger assembly. The beam comprises a plurality of hollow assemblies, each of which includes at least two boards and side walls connecting the boards. Each portion of the cross-section of the beam has hollow assemblies nested within one another.
Description
`, ~ 63774 P27ll - 1 -BAC~GROUND OF THE INVENTION
1. Field of the Invention The present invention relates to the manufacture of wooden beams adapted particularly to form frames of great expanse. These frames are particularly useful for the construction of ~arge exhibit halls, gymnasiums, and all locations of vast dimensions, in general, in which the interior space must be free of all structural elements.
The extent of the frames which cover such structures necessitate the use of beams having the following characteristics:
a) minimum weight; and b) capable of supporting, obviously, at each cross-section, the forces to which the cross-section is subjected.
Furthermore, it is important that any such system allows for:
a) transmiscion of the weight of the beams over the dimensions of the support elements of the frame;
b) savings of raw materials made out of wood; and c) ease and speed of maintenance of porticos whose cost of assembly sometimes renders the cost of such an embodiment considerably more expensive.
The above structural requirements have`led to the manufacture of beams whose cross-section is adapted in a manner so as to support flexional as well as shear forces which are identical to those supported by a beam~
of solid square cross-section of greater weight.
1. Field of the Invention The present invention relates to the manufacture of wooden beams adapted particularly to form frames of great expanse. These frames are particularly useful for the construction of ~arge exhibit halls, gymnasiums, and all locations of vast dimensions, in general, in which the interior space must be free of all structural elements.
The extent of the frames which cover such structures necessitate the use of beams having the following characteristics:
a) minimum weight; and b) capable of supporting, obviously, at each cross-section, the forces to which the cross-section is subjected.
Furthermore, it is important that any such system allows for:
a) transmiscion of the weight of the beams over the dimensions of the support elements of the frame;
b) savings of raw materials made out of wood; and c) ease and speed of maintenance of porticos whose cost of assembly sometimes renders the cost of such an embodiment considerably more expensive.
The above structural requirements have`led to the manufacture of beams whose cross-section is adapted in a manner so as to support flexional as well as shear forces which are identical to those supported by a beam~
of solid square cross-section of greater weight.
2. Discussion of Prior Art In a general fashion, a traditional beam comprises a vertical core connecting two horizontal boards which are respectively attached to the upper and lower portions of this core.
~ 1 6~77 ~
1~2711 - 2 -In practice, these elements are made of various conf;gurations such that the beam has, at each of its cross-sections, a resistance which is at least equal to that necessary to support the forces to which the S section will be subjected. Thus, the core can be solid or more or less hollow, e.g., the beam can be trellisèd by virtue of simple cross-beam supports. On the other hand, the boards can be organized in very diverse fashions. The boards can either be symmetric or not, as desired, with a single ply or with a plurality of plies flattened on one another to constitute frameworks whose elementary plies are appropriately distributed in length and width in a fashion so as to correspond to the load to be supported in each section.
These various embodiments are exploited in the wood frame techniques, and particularly in using glued layered wood.
According to the terminology used in this art and for clarification of the description which follows, a "framework" is used to designatë the entire assembly of boards glued flat against one another, each of these boards generally having the same thickness to facilitate their use on construction sites where the frameworks are used at the upper and lower portions of a beam.
Generally, the quantity of material, i.e., wood, utilized for the manufacture of various types of beams is substantially greater than that required by the respective flexional moment and shear force diagrams obtained by conventional calculations relating to material resistance. In effect, since the beams are always subjected simultaneously to flexional and shear forces, each section of a standard type should be dimensioned such that it resists the more substantial of these two forces. As a result, there is a "waste"
of material because there are in practically all I ~ ~37~
sections quantities of excess materials provided for the purpose of withstanding one of the forces by virtue of the dimensions imposed by the other ~orce on a material of given cross-section.
It has long been well known to limit this waste by modulating the dimensions of the frameworks in each cross-section, i.e., by varying the length and width of the boards which form the framework as well as the number of boards so as to adapt them to the total thickness. However, this results in two disadvantages:
a) the "profile" or configuration of the beams is not better modulated in this fashion, i.e., is not better adapted, except with respect to flexional forces because the boards essentially contribute to the resistance of flexional forces; and b) it is difficult to simultaneously achieve a simple modulation of the core, whose function instead is to resist shear forces, since the difficulties of forming a beam whose core has a thickness or a height which is modulated along the length of the cross-section at the same time as the boards are modulated along their sides are relatively large.
As a result, one often compromises by simply modulating the framework boards and by preserving a simple beam structure by virtue of using a working core which is not modulated or only slightly modulated, which in effect amounts to accepting the usè of boards provided with an excess of material in order to resist the shear forces in zones in which the flexional forces are nevertheless weak.
- SUMMARY OF THE INVE~TION
The present invention has as a principal aim to completely overcome this disadvantage in a simple fashion, while permitting the beam constructor to simu]taneously exactly "proportion" his material in various cross-sections along a single beam along a 377~
plurality of transverse axes, and particularly along two perpendicular axes. This can be done without appreciable complication of the processes of constructing the beam.
For this purpose, the process of the invention provides for the manufacture of a beam which is unique in that one portion of the beam frameworks are joined by at least two working sides registered entirely on the interior of the framework group in a fashion so as to constitute a hollow assembly which may be integrated within another assembly formed in the same manner and mating exactly interiorly of the exterior shape and form of the first hollow assembly.
In order to carry out the invention, a hollow assembly is "nested" within another hollow assembly of larger dimensions as many times as necessary by adding as many boards in the horizontal framework each time as is necessary to provide the said cross-section with a flexional resistance corresponding to that required by the load requirements and as many sides in the lateral framework which connects the boards as is necessary to provide to the cross-section a resistance to shear forces which corresponds to that dictated by the load requirements.
Thus, in each transverse cross-section of the beam it is possible to utilize only the minimum of material necessary to assure the necessary flexional resistance as well as the necessary shear resistance.
According to another practical embodiment which is - 30 particularly advantageous, each homogenous portion of the board is given a predetermined height which is a function of the resistance which the beam must exhibit to flexional forces, thereby providing each framework along its entire length with a stepped configuration.
Thus, along each longitudinal cross-section of each framework, it is possible to utilize only the `i I 6377 4 minimum of material which is necessary for the "horizontal" framework.
According to another practical and particularly advantageous embodiment of the invention, when each framework has on both sides lateral grades along its entire length, one attaches each edge concerned with`a working side in a corresponding grade as many times as necessary in order to provide the cross-section of the beam with a shear resistance corresponding to that required by the load distribution.
Thus, along each longitudinal cross-section of the beam, it is possible to utilize only the minimum of material necessary for the "ve~tical" frameworks.
The value of this process of manufacture, which makes it possible to not only vary the thickness of the "horizontal" members as a function of the flexional forces, but also to similarly simultaneously and independently vary the thickness of the "vertical"
frameworks as a function of the shear forces, can be well understood.
In effect, it is possible to attach "working sides" along only a portion of the lateral grades constituted by the edges of the boards and to leave these graded edges free if the moderation of the shear forces allows the same.
According to another particularly advantageous embodiment of the invention, before fixing the working sides of the frameworks, they are cut out of boards in conformance with the profile to be given to the beam, particularly with respect to the lateral profile.
Thus, according to this embodiment, it is possible to form the beam in any-desired configuration because its lateral profile is predetermined by the geometrical configuration of these sides.
The invention relates, of course, to a beam such as may be formed by the above methods wXich is formed 1 ~ 63774 P~711 - 6 ~
from hollow assemblies nested within one another in "Russian-doll" fashion.
The nesting of one hollow~assembly within another (in the fashion of "Russian dolls") is only one way of clescribing the principal idea which is the basis of the invention, and which reflects the splitting of the core into two sides, such that modulation of number and height can thus be "married" to those of the boards.
The invention relates also, obviously, to each of the elemental parts comprising the beam to the extent that these parts are adapted to be used according to the invention.
The present invention is provided for in its first aspect by a process of manufacturing a beam by simultaneously controlling the size of its cross-section in a plurality of transverse directions in order to adapt various portions of the cross-section of the beam to shear forces and to flexional forces to which the beam will be subjected. The process comprises forming the beam by successively nesting a plurality of hollow, differently sized assemblies within one another. Each assembly is formed by joining framework portions of the beam by side walls, the framework comprising a plurality of differently sized boards to which the side walls are attached in order to form the plurality of differently sized hollow assemblies which are respectively nestablè within a larger assembly formed in similar fashion. Each assembly is formed with an exterior dimension suitable to precisely mate with the interior dimension of the next largest hollow assembly.
The present inventi-on is provided for in a second aspect thereof by a beam comprising a plurality of hollow assemblies. Each of the hollow assemblies comprises at least two boards and sides connecting the boards. Each portion o~ the beam cross-section has ~ ,.
i 1 6377~
P~711 - 7 -hollow assemblies nested within one another.
The present invention is provided for in a third aspect thereof by a generally hollow beam comprising a plurality of successively nested hollow assemblies having different widths, each of said assemblies comprising at least two spaced-apart boards attached to each other by opposed side walls, each assembly nested within the next larger width assembly.
BRIEF DESCRIPTION OF THE INVENTION
The invention will be better understood by virtue of the description which follows, given by way of illustration only with reference to the annexed drawings, in which a non-limiting embodiment is illustrated.
Fig. 1 illustrates a conventional flexional moment and shear force diagram for a beam on simple supports;
Fig. 2 is a lateral perspective view of a beam, formed from assemblies nested -wlthin one another according to the invention the working sides of the beam are shown as broken away on one side of this beam;
Fig. 3 is a lateral perspective view of an alternative embodiment of the beam of Fig. 2 with the working sides being shown in part on one side of the beam; and Fig. 4 is a general perspective view of a beam having a hexagonal cross-section and of which one of the sides is shown in broken-away fashion.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Fig. 1, a schematic of a beam 1 resting, at it ends, on two simple supports 2 is illustrated. This beam supports a uniformly distribute-d load, which is not shown for purposes of clarity in ~the drawing.
If an?abscissa 8 is assigned to the beam, each of the transverse and carrier sections can be identified on an ordinate axis 3 with the particular flexional 1 ~ ~37~'1 l~711 - n -force "F" and the shear force "T" which corresponds to this cross-section.
~ y varyin~ the abscissa of this cross-section, the flexional moment curve 4 and the shear force curve 5 can be conventionally plotted.
This process of manufacturing the beam 1 comprises distributing, at each cross-section, material 6 (i.e., wood~ only where necessary.
For example, with reference to Fig.l, it will be noted that where the shear force is "weak", the flexional moment is "strong", and that the reverse is also true. As a result, in the left-hand portion A of axis 8, the material 6 of beam 1 must "fill" zone 7a, which is situated between the curve of flexional moment 4 and that of shear force S.
For the right-hand portion B of axis 8, zone 7b, which is positioned between the horizontal axis 8 and the flexional moment curve 4, i8 similarly "filled"
with material 6 symmetrically with respect to this axis 8. One also "adds", if necessary, material 6 between the two curves 4 and 5 in the zone 7c for which the shear force curve 5 is positioned beneath that of the flexional moment.
For a beam formed according to the invention (Fig.
2), two frameworXs 9, identical to one another, are positioned in symmetrical fashion with respect to the longitudinal geometric axis of the beam. Each framework 9 comprises a plurality of wooden parallelepipedic boards 10a, 10b, and 10c, of various widths and appropriately piled up in the longitudinal direction.
Thus, by virtue of the difference8 in width of these boards, piling of boards 10a and 10b (or 10b and 10c) provid~s respective "grades" llab (or llbc).
35In each of the grades, longitudinal edges of working side walls 12b (or 12cj are-respectively `~ 1 63774 lodged, while the widest board 10a receives, on its lateral and longitudinal surfaces 13a, longitudinal edges of two working sides 1-2à; these surfaces 13a are accordingly entirely covered by the sides.
As a result, each pair of working sides 12a, 12b, or 12c and corresponding boards 10a, 10b, or 10c, on which they are attached by nails 16, forms a respective hollow assembly 14a, 14b, or 14c which, in this example, has the form of a rectangular parallelepiped;
the assemblies are nested within one another.
It will be noted, however, that it is possible to leave the last grades free on a portion of the beam along which the shear force to be supported is weak.
In the case where a supplemental grade would be unnecessary over the entire length of the board, one provides a board lOc whose thickness is double that shown.
One can thus independently marry resistance to the flexion force and the resistance to the shear forces without disturbing the cohesion of the beam assembly.
In the embodiment of Fig. 3, the boards 10a, lOb, and lOc have different lengths from one another, and are piled on one another in a fashion so as to form, in the direction of the length of the beam 1, gradations resulting from a procession of grades 15 which are different from one another.
The hollow assemblies 14a, 14b, and 14c, which are formed respectively by working sides 12a, 12b, and 12c and corresponding boards lOa, 10b, and 10c, have different lengths; the length of beam 1 being equal to that of the hollow assembly 14a, which is the longest.
Fig. 4 illustrates, in perspective, the height and width of beam 1, which, according to the above provisions, has a lateral profile which can take any shape and which is formed out of hollow assemblies 14 nested within one another in "Ru~sian-doll" fashion.
`i 1 63774 The breakaway in Fig. 4 illustrates, clearly, the possibility of forming each of these hollow assemblies out of frameworks 9, constituted by a pair ofboards 10 and working sides 12.
Thus, along all of the sections, one can "marry"
the modulation of the working sides 12 in number and in height with that of the frameworks 9 as a function of the flexional and shear forces.
Furthermore, while assuring a simple structure for the beam, the invention avoids the utilization of excessive material 6, i.e., wood.
Thus, in all of the sections, the quantity of material 6 which is necessary is minimized; and all excess material which does not serve a function is thus avoided. A beam results which is capable of responding to flexional as well as shear forces, and the beam can therefore be characterized as an "iso-beam".
Of course, all of the particular provisions adopted in the manufacture discussed above make it possible to achieve embodiments which are more or less appropriate, but one can, at will, forego certain advantages while nevertheless falling within the scope of the invention by reproduci~ng the essential characteristics of the invention.
Although the invention has been described with - respect to particular means, materials, and embodiments, it is to be understood that the invention is not limited to the particulars disclosed, and extends to all embodiments falling within the scope of the claims.
"
~ 1 6~77 ~
1~2711 - 2 -In practice, these elements are made of various conf;gurations such that the beam has, at each of its cross-sections, a resistance which is at least equal to that necessary to support the forces to which the S section will be subjected. Thus, the core can be solid or more or less hollow, e.g., the beam can be trellisèd by virtue of simple cross-beam supports. On the other hand, the boards can be organized in very diverse fashions. The boards can either be symmetric or not, as desired, with a single ply or with a plurality of plies flattened on one another to constitute frameworks whose elementary plies are appropriately distributed in length and width in a fashion so as to correspond to the load to be supported in each section.
These various embodiments are exploited in the wood frame techniques, and particularly in using glued layered wood.
According to the terminology used in this art and for clarification of the description which follows, a "framework" is used to designatë the entire assembly of boards glued flat against one another, each of these boards generally having the same thickness to facilitate their use on construction sites where the frameworks are used at the upper and lower portions of a beam.
Generally, the quantity of material, i.e., wood, utilized for the manufacture of various types of beams is substantially greater than that required by the respective flexional moment and shear force diagrams obtained by conventional calculations relating to material resistance. In effect, since the beams are always subjected simultaneously to flexional and shear forces, each section of a standard type should be dimensioned such that it resists the more substantial of these two forces. As a result, there is a "waste"
of material because there are in practically all I ~ ~37~
sections quantities of excess materials provided for the purpose of withstanding one of the forces by virtue of the dimensions imposed by the other ~orce on a material of given cross-section.
It has long been well known to limit this waste by modulating the dimensions of the frameworks in each cross-section, i.e., by varying the length and width of the boards which form the framework as well as the number of boards so as to adapt them to the total thickness. However, this results in two disadvantages:
a) the "profile" or configuration of the beams is not better modulated in this fashion, i.e., is not better adapted, except with respect to flexional forces because the boards essentially contribute to the resistance of flexional forces; and b) it is difficult to simultaneously achieve a simple modulation of the core, whose function instead is to resist shear forces, since the difficulties of forming a beam whose core has a thickness or a height which is modulated along the length of the cross-section at the same time as the boards are modulated along their sides are relatively large.
As a result, one often compromises by simply modulating the framework boards and by preserving a simple beam structure by virtue of using a working core which is not modulated or only slightly modulated, which in effect amounts to accepting the usè of boards provided with an excess of material in order to resist the shear forces in zones in which the flexional forces are nevertheless weak.
- SUMMARY OF THE INVE~TION
The present invention has as a principal aim to completely overcome this disadvantage in a simple fashion, while permitting the beam constructor to simu]taneously exactly "proportion" his material in various cross-sections along a single beam along a 377~
plurality of transverse axes, and particularly along two perpendicular axes. This can be done without appreciable complication of the processes of constructing the beam.
For this purpose, the process of the invention provides for the manufacture of a beam which is unique in that one portion of the beam frameworks are joined by at least two working sides registered entirely on the interior of the framework group in a fashion so as to constitute a hollow assembly which may be integrated within another assembly formed in the same manner and mating exactly interiorly of the exterior shape and form of the first hollow assembly.
In order to carry out the invention, a hollow assembly is "nested" within another hollow assembly of larger dimensions as many times as necessary by adding as many boards in the horizontal framework each time as is necessary to provide the said cross-section with a flexional resistance corresponding to that required by the load requirements and as many sides in the lateral framework which connects the boards as is necessary to provide to the cross-section a resistance to shear forces which corresponds to that dictated by the load requirements.
Thus, in each transverse cross-section of the beam it is possible to utilize only the minimum of material necessary to assure the necessary flexional resistance as well as the necessary shear resistance.
According to another practical embodiment which is - 30 particularly advantageous, each homogenous portion of the board is given a predetermined height which is a function of the resistance which the beam must exhibit to flexional forces, thereby providing each framework along its entire length with a stepped configuration.
Thus, along each longitudinal cross-section of each framework, it is possible to utilize only the `i I 6377 4 minimum of material which is necessary for the "horizontal" framework.
According to another practical and particularly advantageous embodiment of the invention, when each framework has on both sides lateral grades along its entire length, one attaches each edge concerned with`a working side in a corresponding grade as many times as necessary in order to provide the cross-section of the beam with a shear resistance corresponding to that required by the load distribution.
Thus, along each longitudinal cross-section of the beam, it is possible to utilize only the minimum of material necessary for the "ve~tical" frameworks.
The value of this process of manufacture, which makes it possible to not only vary the thickness of the "horizontal" members as a function of the flexional forces, but also to similarly simultaneously and independently vary the thickness of the "vertical"
frameworks as a function of the shear forces, can be well understood.
In effect, it is possible to attach "working sides" along only a portion of the lateral grades constituted by the edges of the boards and to leave these graded edges free if the moderation of the shear forces allows the same.
According to another particularly advantageous embodiment of the invention, before fixing the working sides of the frameworks, they are cut out of boards in conformance with the profile to be given to the beam, particularly with respect to the lateral profile.
Thus, according to this embodiment, it is possible to form the beam in any-desired configuration because its lateral profile is predetermined by the geometrical configuration of these sides.
The invention relates, of course, to a beam such as may be formed by the above methods wXich is formed 1 ~ 63774 P~711 - 6 ~
from hollow assemblies nested within one another in "Russian-doll" fashion.
The nesting of one hollow~assembly within another (in the fashion of "Russian dolls") is only one way of clescribing the principal idea which is the basis of the invention, and which reflects the splitting of the core into two sides, such that modulation of number and height can thus be "married" to those of the boards.
The invention relates also, obviously, to each of the elemental parts comprising the beam to the extent that these parts are adapted to be used according to the invention.
The present invention is provided for in its first aspect by a process of manufacturing a beam by simultaneously controlling the size of its cross-section in a plurality of transverse directions in order to adapt various portions of the cross-section of the beam to shear forces and to flexional forces to which the beam will be subjected. The process comprises forming the beam by successively nesting a plurality of hollow, differently sized assemblies within one another. Each assembly is formed by joining framework portions of the beam by side walls, the framework comprising a plurality of differently sized boards to which the side walls are attached in order to form the plurality of differently sized hollow assemblies which are respectively nestablè within a larger assembly formed in similar fashion. Each assembly is formed with an exterior dimension suitable to precisely mate with the interior dimension of the next largest hollow assembly.
The present inventi-on is provided for in a second aspect thereof by a beam comprising a plurality of hollow assemblies. Each of the hollow assemblies comprises at least two boards and sides connecting the boards. Each portion o~ the beam cross-section has ~ ,.
i 1 6377~
P~711 - 7 -hollow assemblies nested within one another.
The present invention is provided for in a third aspect thereof by a generally hollow beam comprising a plurality of successively nested hollow assemblies having different widths, each of said assemblies comprising at least two spaced-apart boards attached to each other by opposed side walls, each assembly nested within the next larger width assembly.
BRIEF DESCRIPTION OF THE INVENTION
The invention will be better understood by virtue of the description which follows, given by way of illustration only with reference to the annexed drawings, in which a non-limiting embodiment is illustrated.
Fig. 1 illustrates a conventional flexional moment and shear force diagram for a beam on simple supports;
Fig. 2 is a lateral perspective view of a beam, formed from assemblies nested -wlthin one another according to the invention the working sides of the beam are shown as broken away on one side of this beam;
Fig. 3 is a lateral perspective view of an alternative embodiment of the beam of Fig. 2 with the working sides being shown in part on one side of the beam; and Fig. 4 is a general perspective view of a beam having a hexagonal cross-section and of which one of the sides is shown in broken-away fashion.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Fig. 1, a schematic of a beam 1 resting, at it ends, on two simple supports 2 is illustrated. This beam supports a uniformly distribute-d load, which is not shown for purposes of clarity in ~the drawing.
If an?abscissa 8 is assigned to the beam, each of the transverse and carrier sections can be identified on an ordinate axis 3 with the particular flexional 1 ~ ~37~'1 l~711 - n -force "F" and the shear force "T" which corresponds to this cross-section.
~ y varyin~ the abscissa of this cross-section, the flexional moment curve 4 and the shear force curve 5 can be conventionally plotted.
This process of manufacturing the beam 1 comprises distributing, at each cross-section, material 6 (i.e., wood~ only where necessary.
For example, with reference to Fig.l, it will be noted that where the shear force is "weak", the flexional moment is "strong", and that the reverse is also true. As a result, in the left-hand portion A of axis 8, the material 6 of beam 1 must "fill" zone 7a, which is situated between the curve of flexional moment 4 and that of shear force S.
For the right-hand portion B of axis 8, zone 7b, which is positioned between the horizontal axis 8 and the flexional moment curve 4, i8 similarly "filled"
with material 6 symmetrically with respect to this axis 8. One also "adds", if necessary, material 6 between the two curves 4 and 5 in the zone 7c for which the shear force curve 5 is positioned beneath that of the flexional moment.
For a beam formed according to the invention (Fig.
2), two frameworXs 9, identical to one another, are positioned in symmetrical fashion with respect to the longitudinal geometric axis of the beam. Each framework 9 comprises a plurality of wooden parallelepipedic boards 10a, 10b, and 10c, of various widths and appropriately piled up in the longitudinal direction.
Thus, by virtue of the difference8 in width of these boards, piling of boards 10a and 10b (or 10b and 10c) provid~s respective "grades" llab (or llbc).
35In each of the grades, longitudinal edges of working side walls 12b (or 12cj are-respectively `~ 1 63774 lodged, while the widest board 10a receives, on its lateral and longitudinal surfaces 13a, longitudinal edges of two working sides 1-2à; these surfaces 13a are accordingly entirely covered by the sides.
As a result, each pair of working sides 12a, 12b, or 12c and corresponding boards 10a, 10b, or 10c, on which they are attached by nails 16, forms a respective hollow assembly 14a, 14b, or 14c which, in this example, has the form of a rectangular parallelepiped;
the assemblies are nested within one another.
It will be noted, however, that it is possible to leave the last grades free on a portion of the beam along which the shear force to be supported is weak.
In the case where a supplemental grade would be unnecessary over the entire length of the board, one provides a board lOc whose thickness is double that shown.
One can thus independently marry resistance to the flexion force and the resistance to the shear forces without disturbing the cohesion of the beam assembly.
In the embodiment of Fig. 3, the boards 10a, lOb, and lOc have different lengths from one another, and are piled on one another in a fashion so as to form, in the direction of the length of the beam 1, gradations resulting from a procession of grades 15 which are different from one another.
The hollow assemblies 14a, 14b, and 14c, which are formed respectively by working sides 12a, 12b, and 12c and corresponding boards lOa, 10b, and 10c, have different lengths; the length of beam 1 being equal to that of the hollow assembly 14a, which is the longest.
Fig. 4 illustrates, in perspective, the height and width of beam 1, which, according to the above provisions, has a lateral profile which can take any shape and which is formed out of hollow assemblies 14 nested within one another in "Ru~sian-doll" fashion.
`i 1 63774 The breakaway in Fig. 4 illustrates, clearly, the possibility of forming each of these hollow assemblies out of frameworks 9, constituted by a pair ofboards 10 and working sides 12.
Thus, along all of the sections, one can "marry"
the modulation of the working sides 12 in number and in height with that of the frameworks 9 as a function of the flexional and shear forces.
Furthermore, while assuring a simple structure for the beam, the invention avoids the utilization of excessive material 6, i.e., wood.
Thus, in all of the sections, the quantity of material 6 which is necessary is minimized; and all excess material which does not serve a function is thus avoided. A beam results which is capable of responding to flexional as well as shear forces, and the beam can therefore be characterized as an "iso-beam".
Of course, all of the particular provisions adopted in the manufacture discussed above make it possible to achieve embodiments which are more or less appropriate, but one can, at will, forego certain advantages while nevertheless falling within the scope of the invention by reproduci~ng the essential characteristics of the invention.
Although the invention has been described with - respect to particular means, materials, and embodiments, it is to be understood that the invention is not limited to the particulars disclosed, and extends to all embodiments falling within the scope of the claims.
"
Claims (18)
1. A process of manufacturing a beam by simultane-ously modulating the size of its cross-section in a plurality of transverse directions in order to adapt various portions of the beam to withstand shear and flexional forces to which the beam will be subjected, said process comprising forming the beam by nesting- a plurality of hollow assemblies of different size within one another, forming each of said assemblies by joining framework portions of said beam by sidewalls, a plu-rality of differently sized hollow assemblies thus being formed which are then nested within successively larger assemblies similarly formed, each assembly being formed with an exterior dimension suitable to precisely mate with the interior dimension of the next largest hollow assembly whereby modulation of said side walls in number and in height with that of the framework portions may be married as a function of the flexional and shear forces.
2. A process in accordance with claim 1 wherein the size of said cross-section is controlled in two perpendicular directions.
3. A process in accordance with claim 1 wherein the number of hollow assemblies utilized is selected as a function of the necessary flexional resistance for the beam as determined by the load distribution thereon.
4. A process in accordance with claim 3 wherein said framework portions comprise a plurality of boards to which said plurality of side walls are attached, the width of the boards of each successively nested assembly increasing towards the exterior of said beam, lateral edges of said boards thus providing a step-like for-mation including a graded surface positioned along the length of each board, the thickness of each board being selected as a function of the flexional resistance to which said beam is to be subjected.
5. A process in accordance with claim 4 wherein said boards form step-like configurations along both sides thereof and wherein borders of said side walls are attached to graded surfaces along both of said sides in order to provide a shear resistance which is determined by the load distribution imposed.
6. A process in accordance with claim 4 further comprising cutting said side walls prior to attachment to said boards in order to conform to the profile of said boards.
7. A process in accordance with claim 6 wherein said side walls are cut so as to conform to the lateral profile of said boards.
8. A construction beam comprising a plurality of hollow assemblies, each of said hollow assemblies com-prising at least two boards and side walls connecting said boards to each other, said assemblies having suc-cessively greater sizes and each assembly being succes-sively nested within the next larger assembly over the entire length of the beam whereby modulation of said side walls in number and in height with that of frameworks of said boards may be married as a function of flexional and shear forces to which the beam will be subjected.
9. A beam in accordance with claim 8 wherein a plurality of piled boards together comprising two frame-works result when said hollow assemblies are nested, said boards having different dimensions and piled over their entire lengths, the respective widths of said piled boards decreasing in a direction from the exterior of said beam towards the interior of said beam, each side wall having dimensions corresponding to the lateral profile of said at least two boards.
10. A beam formed in accordance with claim 9 wherein said side walls are nailed to said boards.
11. A beam in accordance with claim 10 wherein the length of said piled boards decreases in a direction taken from the exterior of the beam towards the interior of the beam.
12. A generally hollow structural beam comprising a plurality of successively nested hollow assemblies having successively increasing widths, as viewed in a direction from the interior of said beam to the exterior of said beam, each of said assemblies comprising at least two spaced apart boards attached by opposed side walls.
13. A generally hollow beam in accordance with claim 12 wherein the boards of said assemblies have different widths and are piled upon each other when said assemblies are nested so as to form a first step-like configuration providing a plurality of graded surfaces.
14. A generally hollow beam in accordance with claim 13 wherein said boards additionally have differing lengths to provide a step-like configuration in a trans-verse direction to said first step-like configuration, said assemblies also having different lengths.
15. A generally hollow beam in accordance with claim 12 wherein each of said assemblies comprises a rectangular parallelepiped.
16. A generally hollow beam in accordance with claim 12 further comprising a plurality of side walls attached to said at least two spaced apart boards.
17. A generally hollow beam in accordance with claim 12 wherein at least one of said assemblies com-prises two pairs of spaced apart boards.
18. A generally hollow beam in accordance with claim 17 wherein said at least one assembly comprises the innermost assembly.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8009231 | 1980-04-24 | ||
| FR8009231A FR2481343A1 (en) | 1980-04-24 | 1980-04-24 | PROCESS FOR THE MANUFACTURE OF A BEAM, FROM HOLLOW ASSEMBLIES FITTED INTO ONE ANOTHER, AND "ISO-BEAM" THUS OBTAINED |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1163774A true CA1163774A (en) | 1984-03-20 |
Family
ID=9241320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000375901A Expired CA1163774A (en) | 1980-04-24 | 1981-04-22 | Iso-beam and process for its manufacture from nested hollow assemblies |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS56163353A (en) |
| BE (1) | BE888420A (en) |
| CA (1) | CA1163774A (en) |
| DE (1) | DE3115473A1 (en) |
| FR (1) | FR2481343A1 (en) |
| GB (1) | GB2074628A (en) |
| NL (1) | NL8102029A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5809735A (en) * | 1996-08-19 | 1998-09-22 | Les Bois Laumar Inc. | Steel-wood system |
| US6167675B1 (en) | 1996-08-19 | 2001-01-02 | Les Bois Laumar, Inc. | Steel-wood system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0742759B2 (en) * | 1990-10-12 | 1995-05-10 | 川鉄建材工業株式会社 | Double steel pipe type structural member for truss |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL75638C (en) * | 1900-01-01 | |||
| FR852583A (en) * | 1939-04-04 | 1940-02-27 | Christoph & Unmack Ag | Wooden beam |
| GB782900A (en) * | 1954-06-16 | 1957-09-18 | Denis Winfield Cooper | Improvements relating to non-metallic structural work |
| FR1423278A (en) * | 1965-01-29 | 1966-01-03 | Wooden beam |
-
1980
- 1980-04-24 FR FR8009231A patent/FR2481343A1/en active Granted
-
1981
- 1981-04-14 BE BE0/204484A patent/BE888420A/en not_active IP Right Cessation
- 1981-04-16 DE DE19813115473 patent/DE3115473A1/en not_active Withdrawn
- 1981-04-21 JP JP6049381A patent/JPS56163353A/en active Pending
- 1981-04-22 CA CA000375901A patent/CA1163774A/en not_active Expired
- 1981-04-23 GB GB8112562A patent/GB2074628A/en not_active Withdrawn
- 1981-04-24 NL NL8102029A patent/NL8102029A/en not_active Application Discontinuation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5809735A (en) * | 1996-08-19 | 1998-09-22 | Les Bois Laumar Inc. | Steel-wood system |
| US6167675B1 (en) | 1996-08-19 | 2001-01-02 | Les Bois Laumar, Inc. | Steel-wood system |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3115473A1 (en) | 1982-02-11 |
| FR2481343A1 (en) | 1981-10-30 |
| JPS56163353A (en) | 1981-12-15 |
| NL8102029A (en) | 1981-11-16 |
| BE888420A (en) | 1981-07-31 |
| GB2074628A (en) | 1981-11-04 |
| FR2481343B1 (en) | 1983-08-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |