CA1219721A - Beam for shoring structure - Google Patents
Beam for shoring structureInfo
- Publication number
- CA1219721A CA1219721A CA000442193A CA442193A CA1219721A CA 1219721 A CA1219721 A CA 1219721A CA 000442193 A CA000442193 A CA 000442193A CA 442193 A CA442193 A CA 442193A CA 1219721 A CA1219721 A CA 1219721A
- Authority
- CA
- Canada
- Prior art keywords
- web
- flange
- bottom flange
- plies
- tails
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- E04C3/29—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures
- E04C3/292—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures the materials being wood and metal
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G11/00—Forms, shutterings, or falsework for making walls, floors, ceilings, or roofs
- E04G11/36—Forms, shutterings, or falsework for making walls, floors, ceilings, or roofs for floors, ceilings, or roofs of plane or curved surfaces end formpanels for floor shutterings
- E04G11/48—Supporting structures for shutterings or frames for floors or roofs
- E04G11/50—Girders, beams, or the like as supporting members for forms
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Mechanical Engineering (AREA)
- Rod-Shaped Construction Members (AREA)
Abstract
BEAM FOR SHORING STRUCTURE
ABSTRACT OF THE DISCLOSURE
The beam disclosed has a bulky wooden top flange, an extruded aluminum bottom flange, and a plywood web.
The web is tailed-in to the two flanges to form a unitary whole. The structure takes advantage of the rigidity of wood under compression and the strength of a slim extruded section of aluminum under tension.
ABSTRACT OF THE DISCLOSURE
The beam disclosed has a bulky wooden top flange, an extruded aluminum bottom flange, and a plywood web.
The web is tailed-in to the two flanges to form a unitary whole. The structure takes advantage of the rigidity of wood under compression and the strength of a slim extruded section of aluminum under tension.
Description
- ~2~L~72~
..vKGROUND TO TH~ INVENTIO~
This invention relates to beams for sh~ring structures, ~he main use of such structures being to serve as a temporary support during the formation of collcrete slabs.
The beams ior shoring structures must first of all be strong enough, so that they will not fail under the weight of the concrete even under abusive conditions. Apar~ from that paramount requirement, the beams should be light iTl weight ior easy assembly and removal of the shoring structure as the building progresses: and since many beams are needed to support a large concrete slab, each beam also should be inexpensive in itself, and should be easily manufactured in production quantities.
PRIOK AR~
An examplc of a typical stringer that has ~een use~d hitherto is tllat shown in Canadian ~atent l~o. 1,1~,127 (JOHN~rr~, 4 August 1~81). The beam is forme-l as an aluminum extrusion. ~`lle cross-sectional shape of the extrusion inclucles a boLtolrl flange having a wide, flat, tllin base; a comparaLively slender we~; and a challnel-shaped top section in the form ol an inverted top hat. A
strip of wood Lits in~o the upper top hat channel and is provided for the purpose of receiving nails or screws so tha~ a declcing board may be nailed do~.7rl to the top oL the beam. ~`he~ scrip of ~ood is secured in the top hat channel by screws which pass through the si~es of the channel. This JO~ TOi~' stringer is, itself, an improved and more robust design compared with those sho~n in AV~Y U.~. ~atents 27 4,144,690 (i~larch 2~, 1479), 3,89~,152 (August 12, 1975) an~ 3,787,~2 ~23L~2~
(January 22, 1974).
In U.S. Patent 4,159,604 (BURRELL, 3 July 1979) the wooden strip is secured by barbs formed in the sides of the trough. It is plain that in such arrangements the capacity of the wood to contribute to the structural strength and stiffness of the beam is quite limited: when the beam deflects under load, there is some relative movement between the wood and the metal permitted by such jointing means as those illustrated.
It is a]so known from U.S. 4,191,000 (HENDERSON, 04 March 1980) to provide a composite beam for shoring structures in which the beam is made entirely of wood. The top and bottom flanges are rectangular sections of wood in which the grain runs along the length of the beam. The flanges are joined by a web of wood that is "tailed'in" to both flanges, i.e., slots are cut in the flanges and complementary tails on the web are a tight fit in the slots, and are glued into the slots. In this case, the joint between the web and the flange is a very strong one: now, the wood of a flange cannot deflect or flex independently of a corresponding flexure in the web. the strength of the web therefore complements that of the flange, and vice versa.
BRIEF DESCRIPTION OF THE INVENTION
It is recognized by the present invention that the performance of a beam as a shoring support can be enchanced by a combination of features from the two types of previous construction as described above. It is recognized that wood is well-suited for taking compressive forces: its bulk ensures that it resists buckling under 72~
., .
~ pression, and the disruptive induced shear sLresses which woul~ ~e incurred during such buckling.
ln a beam, it is bad practice on the other hand to employ wood in tension: wood can have knots in it which seriously reduce its tensile strength (though they hardly afLect its rigidity under cornpression.) ~ince the beam cannot be allowed to fail, the designer must allow a huge factor of safety, which is not neecled when the woo~i is only in compression.
~ ther materials have other characteristics: aluminum, or other extruded materials, cannot have a thick and bulky section as that would be too expensive. lt is uneconolnical for extruded shapes to be anything but thin, though, of course, the shapes can be intricate.
These shape characterisLics mean that whilst an extruded shape is MUCh superior Lo WoO(I in supporting tensile forces, wood is the one that is l-nore suiLt(l ~o takirlg coml~ressive rorces, at leas~ with the type of loadiTlg and the n-lanller of use enco-lllLered in ~eams for shoring strucLu1-e~s.
In ~he inve~Tltiorl~ the top flange of the beanl (whicll is uTlder coml)ressioll wherl lhe beam is loaded) is wood, ancl the bottonl flange (which is under Lension) is extruclecd. l`he flanges are joined by a web t~lat renders ~I-le beam a unitary whole. ~ucll a beam ccln be used in the same rnanner as the knowl- beanls with ~he all-extruded secLion an(l a wood insert, since a wooclen surface is preseTlted on top for the nailirlg down of boal-(ls, and the extruded shape of the bottor;l flange can include Lhe c~lstomary T-s]ots for retaining bolts.
Preferably, the ~wo flanges are joined to the web by tailing-in 27 the web, which is conveniently of a lamil-lated or sandwich construction. The tails can be provided on the bottom flange by 12~97Z~
,., ~. ., ~ropriate shaping of the extruded sectin.
DETAILE~ SC~IPTI~N ()l THE PR~F~K~D ~i~lB~Dl~ T
An exemplary embodiment of the invention will now be described with reference to the accompanying drawing, in which:
Figure 1 is a cross-section oc a beam that emboclies the invention.
The beam of Figure 1 includes a top flange 4, a ~ottom flange 5 and a web 6. The top flan~e 4 is of wood, arranged with its grain disposecl along the length of the beam, i.e., perpenclicular to the plane of the ligure. The bot~om flange 5 is of aluminum and the cross-section shown in the Figure has the shape in whicl-l ~he aluminum was extrude(l.
The extruded shape oi- the bottom flange S inclucles a wi~e base 50 comprised by the two lirnbs 51, 5~. I.ach linlb has a respective beacl 53, 57 at its extremity. The extrucled shape inclucles a T-shaped slot 5~ that runs the length of the beam. t'rotrudillg upwarus from the material on top of the slot 5~ are two tails 5~.
The top flange 4 is made of woocl of a rectangular section. Four slots 4~ are cut in the undersurface of the flan~e 4. The slots 4 are slightly tapered.
The web 6 has seven plies, in the plics ~() the grain runs vertically, whereas in t-he plies 61, 62, ~3 the grain runs along the length of the beam. The lengthwise-grained plies ~1, 62, 63 are cut away at the top of the web, so as to leave tails ~4 that extend from 27 the plies 6~. Par~ of the vertically-grained plies 6~ are also cut away to leave the tails slightly tapered. The two outer `` ~2~7Z~
~ gthwise-grainecl plies 61,63 are cut away at the bottom of the beam, to leave slots 67.
To assemble the beam, the tails 64 on top of the wer~ 6 are inserted into the slots 40 in the top flange 4. The tails 54 on the bottom flange 5 are inserted into the slots 67 in the bottom of the web 6. Each tail is made a goocl tight fit in its respective slot so that the components of the beam have to be pressed together to bed down the tails fully into the slots. The tails and slots are glued during assembly. This manner of joining components oc beams togetl,er is ~nown as "~ailing-in". It produces a joint of generally greater strength than ~he materials of the components (i.e., if the beam fails, it very rarely does so at the joints). The slots and tails shoulc] be accura~ely made to ensure a good fit, but there is little problern in Lhis regard once a production set up has been made: the woo(3en cooponents can be milled to shape using suitable jigs and Eixtures whilst the extrucled component is precise enough as extruded.
I~hen made properly, the joint permits absolutely no relative rnovement ~etwcerl its components: any flexure of the one must be accornpaniecl by a commensurate flexure of the other.
It is recognizecl in ttle invention that tailing-in an extrudcd component to a wooden coponerlt produces a joint between the two of tlle require(3 strerlgtll and reliability, yet with no great expense.
In use, quantities of beams are assembled in such a way that flat l)oards may be laid on top, and nailed down to tne beams. The top-f]ange 4, being of wood, readily accepts nails or screws. lf desired, cross-braces can be installed between beams and nailed to 27 the exposecl sides of the rectangular shape of the top flange 4. (ln tne all-extruded beam of the prior art, even with the wood insert, ~2~L~37~
assembly had to be carried out on the basi.s that cross-braces could not be attached between the beams, because the sides of the wood insert were not exposed.) l`he beams of the invention are light enough for them to ta~e their place in shoring structures of the flying variety. Iierè, the beams are assembled to provide a shoring structure on whici-l a concrete floor is poured, in the usual way; but when the concrete has set, the shoring structure is not dismantled but is caused ~o slide bodily horizontally until clear of the floor on top of it. It is then lifted by crane, and laid upon an upper floor so as to be ready to shore another concrete floor without dèlay.
Since ~he flying shoring structure has to be lifted substantially at thè limit of the crane's reach, it is very important that the structure should be light; and the strength-to-weight ratio o the beam o the invention is very good as compared with prior art beanls. The stress i.n a shoring structure whilst it is being flown from the crane can cause the structure to distort: thc ability of the beam of the invention to receive cross-braces or bridging-braces between the beanls means that the structure can easily be given the required stiflness that i.t needs to survive the flying operation without damage.
0ther refinements oL the beam of the inventiorl include the provision of the beads 53,57 at ~he extremities of the base 5~. These beads receivc clamping clips to hold the beam down onto another beam acting as a stringer running cross-wise below, or on~o other suitable supports; or for securing otller parts such as pan-forms to the beam.
27 The beads 53, 57 also act to concentra~e the mass of the base at the edges, for good strength and stability.
231~7~
The undersur~ace of the base 50 may be slightly concave to ensure good stability of the base.
The T~slot 5~ is provided to receive tlle head of a bolt, also for holding the beam down onto its support, or for mounting and hanging other parts from the beam.
With the invention, some degreee of versatility is providecl.
The extruded shape of the bottom flange 5, being extruded might be difficult to change, but the top flange and the web can be readily changed. Similarly, if the wooden parts deteriorate, the extruded part can be fitted with new wooden parts. The web 6 itself has a good deal of bulkiness as compared with the slender web of the all-extrucled beam, which means that the web can be taller, without the web being liable to a buckling failure.
The beam has been described when used horizontally and wilh the wood flange upmost. In shoring structures, sometimes the beams need to be clisposecl vertically or horizontally witl- the flanges at the sides. This can be appropriate when shorirlg walls or columns for instance. I`he beam of the invention can still be used in such circumstances, though it should of course be arranged that tl~e properties of the beam are used to the best advantage in that the bulky wooclen flange is the one that is preclorninantly in com~ression and the comparatively slim-sectioned extrudecl flange is the one that is predominantly in tension.
The material of the extrusion may be other than aluminum. It could be titanium, or it could be a glass-filled plastic resin. The matcrial of the web may be other than plywood, in that the plies that 27 cornprise the tails could be of metal or plastic. There may be more or fewer plies than seven. Likewise, instead of the two tails 5~, a
..vKGROUND TO TH~ INVENTIO~
This invention relates to beams for sh~ring structures, ~he main use of such structures being to serve as a temporary support during the formation of collcrete slabs.
The beams ior shoring structures must first of all be strong enough, so that they will not fail under the weight of the concrete even under abusive conditions. Apar~ from that paramount requirement, the beams should be light iTl weight ior easy assembly and removal of the shoring structure as the building progresses: and since many beams are needed to support a large concrete slab, each beam also should be inexpensive in itself, and should be easily manufactured in production quantities.
PRIOK AR~
An examplc of a typical stringer that has ~een use~d hitherto is tllat shown in Canadian ~atent l~o. 1,1~,127 (JOHN~rr~, 4 August 1~81). The beam is forme-l as an aluminum extrusion. ~`lle cross-sectional shape of the extrusion inclucles a boLtolrl flange having a wide, flat, tllin base; a comparaLively slender we~; and a challnel-shaped top section in the form ol an inverted top hat. A
strip of wood Lits in~o the upper top hat channel and is provided for the purpose of receiving nails or screws so tha~ a declcing board may be nailed do~.7rl to the top oL the beam. ~`he~ scrip of ~ood is secured in the top hat channel by screws which pass through the si~es of the channel. This JO~ TOi~' stringer is, itself, an improved and more robust design compared with those sho~n in AV~Y U.~. ~atents 27 4,144,690 (i~larch 2~, 1479), 3,89~,152 (August 12, 1975) an~ 3,787,~2 ~23L~2~
(January 22, 1974).
In U.S. Patent 4,159,604 (BURRELL, 3 July 1979) the wooden strip is secured by barbs formed in the sides of the trough. It is plain that in such arrangements the capacity of the wood to contribute to the structural strength and stiffness of the beam is quite limited: when the beam deflects under load, there is some relative movement between the wood and the metal permitted by such jointing means as those illustrated.
It is a]so known from U.S. 4,191,000 (HENDERSON, 04 March 1980) to provide a composite beam for shoring structures in which the beam is made entirely of wood. The top and bottom flanges are rectangular sections of wood in which the grain runs along the length of the beam. The flanges are joined by a web of wood that is "tailed'in" to both flanges, i.e., slots are cut in the flanges and complementary tails on the web are a tight fit in the slots, and are glued into the slots. In this case, the joint between the web and the flange is a very strong one: now, the wood of a flange cannot deflect or flex independently of a corresponding flexure in the web. the strength of the web therefore complements that of the flange, and vice versa.
BRIEF DESCRIPTION OF THE INVENTION
It is recognized by the present invention that the performance of a beam as a shoring support can be enchanced by a combination of features from the two types of previous construction as described above. It is recognized that wood is well-suited for taking compressive forces: its bulk ensures that it resists buckling under 72~
., .
~ pression, and the disruptive induced shear sLresses which woul~ ~e incurred during such buckling.
ln a beam, it is bad practice on the other hand to employ wood in tension: wood can have knots in it which seriously reduce its tensile strength (though they hardly afLect its rigidity under cornpression.) ~ince the beam cannot be allowed to fail, the designer must allow a huge factor of safety, which is not neecled when the woo~i is only in compression.
~ ther materials have other characteristics: aluminum, or other extruded materials, cannot have a thick and bulky section as that would be too expensive. lt is uneconolnical for extruded shapes to be anything but thin, though, of course, the shapes can be intricate.
These shape characterisLics mean that whilst an extruded shape is MUCh superior Lo WoO(I in supporting tensile forces, wood is the one that is l-nore suiLt(l ~o takirlg coml~ressive rorces, at leas~ with the type of loadiTlg and the n-lanller of use enco-lllLered in ~eams for shoring strucLu1-e~s.
In ~he inve~Tltiorl~ the top flange of the beanl (whicll is uTlder coml)ressioll wherl lhe beam is loaded) is wood, ancl the bottonl flange (which is under Lension) is extruclecd. l`he flanges are joined by a web t~lat renders ~I-le beam a unitary whole. ~ucll a beam ccln be used in the same rnanner as the knowl- beanls with ~he all-extruded secLion an(l a wood insert, since a wooclen surface is preseTlted on top for the nailirlg down of boal-(ls, and the extruded shape of the bottor;l flange can include Lhe c~lstomary T-s]ots for retaining bolts.
Preferably, the ~wo flanges are joined to the web by tailing-in 27 the web, which is conveniently of a lamil-lated or sandwich construction. The tails can be provided on the bottom flange by 12~97Z~
,., ~. ., ~ropriate shaping of the extruded sectin.
DETAILE~ SC~IPTI~N ()l THE PR~F~K~D ~i~lB~Dl~ T
An exemplary embodiment of the invention will now be described with reference to the accompanying drawing, in which:
Figure 1 is a cross-section oc a beam that emboclies the invention.
The beam of Figure 1 includes a top flange 4, a ~ottom flange 5 and a web 6. The top flan~e 4 is of wood, arranged with its grain disposecl along the length of the beam, i.e., perpenclicular to the plane of the ligure. The bot~om flange 5 is of aluminum and the cross-section shown in the Figure has the shape in whicl-l ~he aluminum was extrude(l.
The extruded shape oi- the bottom flange S inclucles a wi~e base 50 comprised by the two lirnbs 51, 5~. I.ach linlb has a respective beacl 53, 57 at its extremity. The extrucled shape inclucles a T-shaped slot 5~ that runs the length of the beam. t'rotrudillg upwarus from the material on top of the slot 5~ are two tails 5~.
The top flange 4 is made of woocl of a rectangular section. Four slots 4~ are cut in the undersurface of the flan~e 4. The slots 4 are slightly tapered.
The web 6 has seven plies, in the plics ~() the grain runs vertically, whereas in t-he plies 61, 62, ~3 the grain runs along the length of the beam. The lengthwise-grained plies ~1, 62, 63 are cut away at the top of the web, so as to leave tails ~4 that extend from 27 the plies 6~. Par~ of the vertically-grained plies 6~ are also cut away to leave the tails slightly tapered. The two outer `` ~2~7Z~
~ gthwise-grainecl plies 61,63 are cut away at the bottom of the beam, to leave slots 67.
To assemble the beam, the tails 64 on top of the wer~ 6 are inserted into the slots 40 in the top flange 4. The tails 54 on the bottom flange 5 are inserted into the slots 67 in the bottom of the web 6. Each tail is made a goocl tight fit in its respective slot so that the components of the beam have to be pressed together to bed down the tails fully into the slots. The tails and slots are glued during assembly. This manner of joining components oc beams togetl,er is ~nown as "~ailing-in". It produces a joint of generally greater strength than ~he materials of the components (i.e., if the beam fails, it very rarely does so at the joints). The slots and tails shoulc] be accura~ely made to ensure a good fit, but there is little problern in Lhis regard once a production set up has been made: the woo(3en cooponents can be milled to shape using suitable jigs and Eixtures whilst the extrucled component is precise enough as extruded.
I~hen made properly, the joint permits absolutely no relative rnovement ~etwcerl its components: any flexure of the one must be accornpaniecl by a commensurate flexure of the other.
It is recognizecl in ttle invention that tailing-in an extrudcd component to a wooden coponerlt produces a joint between the two of tlle require(3 strerlgtll and reliability, yet with no great expense.
In use, quantities of beams are assembled in such a way that flat l)oards may be laid on top, and nailed down to tne beams. The top-f]ange 4, being of wood, readily accepts nails or screws. lf desired, cross-braces can be installed between beams and nailed to 27 the exposecl sides of the rectangular shape of the top flange 4. (ln tne all-extruded beam of the prior art, even with the wood insert, ~2~L~37~
assembly had to be carried out on the basi.s that cross-braces could not be attached between the beams, because the sides of the wood insert were not exposed.) l`he beams of the invention are light enough for them to ta~e their place in shoring structures of the flying variety. Iierè, the beams are assembled to provide a shoring structure on whici-l a concrete floor is poured, in the usual way; but when the concrete has set, the shoring structure is not dismantled but is caused ~o slide bodily horizontally until clear of the floor on top of it. It is then lifted by crane, and laid upon an upper floor so as to be ready to shore another concrete floor without dèlay.
Since ~he flying shoring structure has to be lifted substantially at thè limit of the crane's reach, it is very important that the structure should be light; and the strength-to-weight ratio o the beam o the invention is very good as compared with prior art beanls. The stress i.n a shoring structure whilst it is being flown from the crane can cause the structure to distort: thc ability of the beam of the invention to receive cross-braces or bridging-braces between the beanls means that the structure can easily be given the required stiflness that i.t needs to survive the flying operation without damage.
0ther refinements oL the beam of the inventiorl include the provision of the beads 53,57 at ~he extremities of the base 5~. These beads receivc clamping clips to hold the beam down onto another beam acting as a stringer running cross-wise below, or on~o other suitable supports; or for securing otller parts such as pan-forms to the beam.
27 The beads 53, 57 also act to concentra~e the mass of the base at the edges, for good strength and stability.
231~7~
The undersur~ace of the base 50 may be slightly concave to ensure good stability of the base.
The T~slot 5~ is provided to receive tlle head of a bolt, also for holding the beam down onto its support, or for mounting and hanging other parts from the beam.
With the invention, some degreee of versatility is providecl.
The extruded shape of the bottom flange 5, being extruded might be difficult to change, but the top flange and the web can be readily changed. Similarly, if the wooden parts deteriorate, the extruded part can be fitted with new wooden parts. The web 6 itself has a good deal of bulkiness as compared with the slender web of the all-extrucled beam, which means that the web can be taller, without the web being liable to a buckling failure.
The beam has been described when used horizontally and wilh the wood flange upmost. In shoring structures, sometimes the beams need to be clisposecl vertically or horizontally witl- the flanges at the sides. This can be appropriate when shorirlg walls or columns for instance. I`he beam of the invention can still be used in such circumstances, though it should of course be arranged that tl~e properties of the beam are used to the best advantage in that the bulky wooclen flange is the one that is preclorninantly in com~ression and the comparatively slim-sectioned extrudecl flange is the one that is predominantly in tension.
The material of the extrusion may be other than aluminum. It could be titanium, or it could be a glass-filled plastic resin. The matcrial of the web may be other than plywood, in that the plies that 27 cornprise the tails could be of metal or plastic. There may be more or fewer plies than seven. Likewise, instead of the two tails 5~, a
2~Z~
~ .lgle extruded tail coulc~ be accommodated in a single machined slot at the lower end of the web.
.,
~ .lgle extruded tail coulc~ be accommodated in a single machined slot at the lower end of the web.
.,
Claims (17)
1. Beam, having a top flange, a bottom flange, and a web;
wherein the top flange has a cross-sectional shape that is characterized as bulky, having a substantial height and width, and is made of wood;
wherein the bottom flange has a cross-sectional shape that is characterized as non-bulky being in comparatively slim portions and includes a wide, base portion, and wherein the bottom flange is formed by the extrusion of an homogeneous material; and wherein the flanges are joined to the web in such a manner that the two flanges and the web are as one, and together comprise a unitary force-transmitting structure, in that the joint between each flange and the web is so firm and rigid that flexure or strain of the flanges cannot take place independently of a commensurate flexure or strain of the web;
wherein tile web is tailed-in to the top flange, in that at least one slot is formed in the top flange and complementary tails or a tail are formed on the web, and the web is joined to the top flange by glueing the complementary tail or tails into the slot or slots.
wherein the top flange has a cross-sectional shape that is characterized as bulky, having a substantial height and width, and is made of wood;
wherein the bottom flange has a cross-sectional shape that is characterized as non-bulky being in comparatively slim portions and includes a wide, base portion, and wherein the bottom flange is formed by the extrusion of an homogeneous material; and wherein the flanges are joined to the web in such a manner that the two flanges and the web are as one, and together comprise a unitary force-transmitting structure, in that the joint between each flange and the web is so firm and rigid that flexure or strain of the flanges cannot take place independently of a commensurate flexure or strain of the web;
wherein tile web is tailed-in to the top flange, in that at least one slot is formed in the top flange and complementary tails or a tail are formed on the web, and the web is joined to the top flange by glueing the complementary tail or tails into the slot or slots.
2. Beam of claim 1, wherein the material of the top flange is wood of a rectangular cross-section, the top and the two side surfaces of the material of the top flange being exposed.
3. Beam of claim 2, wherein a bolt slot is formed lengthwise of the beam in the bottom surface of the bottom flange, and is centrally located therein.
4. Beam of claim 1, wherein the web comprises plies of material in sandwich or laminate form, disposed so that plies extend between the two flanges, and wherein the tails comprise alternate plies.
5. seam of claim 4, wherein the tails for joining the web to the top flange are comprised by alternating plies of wood in which the grain runs from flange to flange.
6. Beam of claim 1, wherein the web is tailed-in to the bottom flange, in that at least one slot is formed in the web and complementary tails or a tail are formed as part of the extruded cross-sectional shape of the bottom flange, and the web is joined to the bottom flange by glueing the tail or tails into the slot or slots.
7. Beam of claim 6, wherein a bolt slot is formed lengthwise of the beam in the bottom surface of the bottom flange, and is centrally located in the bottom flange.
8. Beam of claim 7, wherein the bottom flange has two tails.
9. Beam of claim 7, wherein the material of the bottom flange is extruded aluminum.
10. Beam of claim 7, wherein the web comprises plies of material in sandwich or laminate form, disposed so that plies extend between the flanges, and wherein the slots comprise cut-outs in non-adjacent plies.
11. Beam of claim 10, wherein the slots for joining the web to the bottom flange are cut from alternating plies of wood in which the grain runs along the length of the beam.
12. Beam of claim 10, wherein the joint between the web and the bottom flange further comprises means for clamping the plies of the web firmly to the tails on the bottom flange.
13. Beam of claim 1, wherein the material of the bottom flange is extruded aluminum.
14. Beam of claim 2, wherein the web comprises plywood.
15. Beam of claim 2, wherein the web comprises a sandwich or laminate of alternating layers of wood and metal.
16. Beam of claim 1, wherein the material of the bottom flange is extruded plastic containing fillers or inclusions to improve the tensile strength of the plastic.
17. Beam of claim 1, wherein the material of the bottom flange is extruded titanium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000442193A CA1219721A (en) | 1983-11-29 | 1983-11-29 | Beam for shoring structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000442193A CA1219721A (en) | 1983-11-29 | 1983-11-29 | Beam for shoring structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219721A true CA1219721A (en) | 1987-03-31 |
Family
ID=4126630
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000442193A Expired CA1219721A (en) | 1983-11-29 | 1983-11-29 | Beam for shoring structure |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1219721A (en) |
-
1983
- 1983-11-29 CA CA000442193A patent/CA1219721A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |