CA1143534A - Girder - Google Patents
GirderInfo
- Publication number
- CA1143534A CA1143534A CA000346618A CA346618A CA1143534A CA 1143534 A CA1143534 A CA 1143534A CA 000346618 A CA000346618 A CA 000346618A CA 346618 A CA346618 A CA 346618A CA 1143534 A CA1143534 A CA 1143534A
- Authority
- CA
- Canada
- Prior art keywords
- chords
- girder
- struts
- recesses
- binding substance
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Rod-Shaped Construction Members (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
- Conveying And Assembling Of Building Elements In Situ (AREA)
Abstract
Abstract A lattice type girder has upper and lower chords between which extend inclined struts. The struts may be of continuous zig-zag form with interconnected sections. The ends of the struts or strut sections are received in recesses in the chords and secured therein by a hardening and binding substance, such as urethane plastics or epoxy glue. This substance fills the recesses and preferably has the same compressive and tensile strength as the material of the chords.
Description
3~34 The present invention relates to a girder of lattice type, comprising an upper and a lower chord of wood and between the chords inclined metal struts Eastened to the chords in a zig-zag pattern.
In earlier girders of this type ~he struts are attached to the chords by clamping means or by other fastening means adapted to enter into the wood material, such as screws or nails.
These fastening means have certain disadvantages, one of which is that the joint between the struts and chords of wood becomes weakened when the wood dries and shrinks. In the case of varying loads, there is furthermore the risk of play arising in the joints.
These disadvantages are serious in that the strength of the girder may become substantially lower than calculated, the result being unexpected failures.
Tlle invention provides a girder of lattice type compris-ing an upper chord and a lower chord, said chords being of wood, and a web of metal consisting of a continuous bar, plate or the like bent to zig-zag form with alternating straight and bent por-tions, the straight portions forming struts between the chords and the bent portions being countersunk into recesses in the chords and fastened therein by a hardening and binding substance.
In this way the weakening of the chords by the recesses for connecting the struts is compensated for by the filling mater-ial. The arrangement also achieves fixing of the joint between the struts and the chords, so that the strength of the joint is not reduced in the course of time by drying of the wood and no play is allowed to develop because the joint is subjected only to resilient deformations.
,. ~
53~
A hardening material which also should adhere both to the wood in the chords and the metal in the struts can be used as the hardening and binding substance. The strength of the material itself and of the joints therebetween and the components must of course be sufficient to resist the forces - la -3~3L~
whicll occur. rhiS meaTls til.lt in ~ener;ll the joini.ng ~ateria]. must havc the s~ e compressive and tensile strength as the mater:i.al in the chords and in the stru~.s. As suitab1e adherillg materials can be mentioned polyurethane plastics and epoxy glue.
Details of the invention will appear from the following speci.fi-cation with appended drawings wherein:
Figure 1 is a side view of a girder accoruing to the invention;
Figure 2 is a perspective view of an individual chord of the girder;
Figure 3 shows a detail in perspective of a joint for the struts;
Figure 4 shows the same detail as in Figure 3 but with joining mat-erial in the joint;
Figure 5 is a side view of the joint;
Figure 6 shows a second embodiment of the joint;
Figure 7 is a side view of a girder with joints according to a third embodiment of the invention;
Figure 8 is a section on a larger scale on the line 8-8 in Figure 7 showing the chord without the struts;
Figure 9 is a section Oll the line 9-9 in Figure 8;
Figure 10 is the same section as in Figure 8 showing both the chord and the struts; and Figure 11 is a section on the line 11-11 in Figure 10.
. In Figure 1 is shown a side view of a girder 10 according to the invention comprisir.g chords or flanges 11 and 12 of wood and a web in the for,n . of inclined struts 13 of metal, suitably steel. The struts can be ~ubular or solid and they can form a continuous zig-zag sha-ped bar as shown in Figure 1.
Possible joints in this bar are placed at the places where the web is counter-sunk into the chords.
Figure 2 shows a separate chord 12 with recesses 15 for the struts 1~353~
13. ~igure :; shows in perspective a detail of how the bent portion 16 hetween two struts in a continuolls zig-zag bar 13 is inserted in a recess 15. Figure 4 sllo\Ys the same view as Figure 3 but with the joint filled with binding mat-erial 17.
Figure 5 shows in a side view how the curved intermediate portion 16 between ~wo struts in a continuous- zig-zag bar is placed at a certain depth below the upper surface of the upper chord 12, so that the binding material 17 covers the portion 16, which firstly improves the strength and secondly improves the heat insulation between the struts and the upper side of the girder. The same is of course also valid for the joints in the lower chord 11 in relation to the lower side thereof.
Figure 6 shows another embodiment of recess 20 where the top 21 of the recess lies below the upper surface of the chord 12. The recess 20 can suitably be machined with a shank-end mill, which can have a plane end or a rounded end depending on what shape the bottom of the recess 20 is supposed to have. The shape can suitably be the same as the shape of the strut, for instance a rounded bottom for a strut having a round section. The recess 15 can also be made with a shank-end mill or can alternatively be made with a straight saw.
Figures 7 to 11 show a further embodiment of the irlvention. The -view in Figure 7 is similar to the one in Figure 1 but the sections in Figures 8 to 11 are different. The reference numbers are also different. The girder 110 comprises a zig-zag bent bar 11 forming inclined struts 114 between two chords, one upper chord 112 and one lower chord 113. The bar 111 is bent in zig_zag form from a bar, a strip or similar and comprises straight portions 114, which form struts in the girder, and bent portions 115 which enter into recesses 116 in the chords.
Figure 8 shows the upper chord 112 in cross section on the line 9-9 S3~
in Figure 7 witll the bar lll re]novecl, and F:i.gure 9 shows the same po:rtion in longitlldillal secti.on on thc line 9-~ in Fi.gure 8. In ~igures 8 and 9 the bar lll has been removed in order to illustrate the recess 116 more clearly.
The web or strut bar 111 is attached to the chords 112 and 113 by inserting the cur~ed portions 115 into the recesses 116 and filling the space between the bar 111 and the recess 116 with a binding substance 117. The joint is illustrated in Figures 10 and ll with the recess 116 shown filled with the fastening substance which surrounds the curved portion and fills the recess 116 up to level with the inside 118 of the chord 112, and correspond-ingly for the lower chord 113. The fastening material in this case is also asuitable hardening and binding substance, for instance polyurethane plastics (resin) or epoxy glue.
In the embodiment in Figures 7 to il the recesses 116 are open only towards the inside of the chords and form a slit in the inside surface. The advantages of this are that as little as possible is removed from the wood in the chords, the pocket formed by the recess gives a firm fastening of the glue joint, and the pocket also forms a seat for the portion 115 which facilitates assembly of the components before applying the glue 117.
In earlier girders of this type ~he struts are attached to the chords by clamping means or by other fastening means adapted to enter into the wood material, such as screws or nails.
These fastening means have certain disadvantages, one of which is that the joint between the struts and chords of wood becomes weakened when the wood dries and shrinks. In the case of varying loads, there is furthermore the risk of play arising in the joints.
These disadvantages are serious in that the strength of the girder may become substantially lower than calculated, the result being unexpected failures.
Tlle invention provides a girder of lattice type compris-ing an upper chord and a lower chord, said chords being of wood, and a web of metal consisting of a continuous bar, plate or the like bent to zig-zag form with alternating straight and bent por-tions, the straight portions forming struts between the chords and the bent portions being countersunk into recesses in the chords and fastened therein by a hardening and binding substance.
In this way the weakening of the chords by the recesses for connecting the struts is compensated for by the filling mater-ial. The arrangement also achieves fixing of the joint between the struts and the chords, so that the strength of the joint is not reduced in the course of time by drying of the wood and no play is allowed to develop because the joint is subjected only to resilient deformations.
,. ~
53~
A hardening material which also should adhere both to the wood in the chords and the metal in the struts can be used as the hardening and binding substance. The strength of the material itself and of the joints therebetween and the components must of course be sufficient to resist the forces - la -3~3L~
whicll occur. rhiS meaTls til.lt in ~ener;ll the joini.ng ~ateria]. must havc the s~ e compressive and tensile strength as the mater:i.al in the chords and in the stru~.s. As suitab1e adherillg materials can be mentioned polyurethane plastics and epoxy glue.
Details of the invention will appear from the following speci.fi-cation with appended drawings wherein:
Figure 1 is a side view of a girder accoruing to the invention;
Figure 2 is a perspective view of an individual chord of the girder;
Figure 3 shows a detail in perspective of a joint for the struts;
Figure 4 shows the same detail as in Figure 3 but with joining mat-erial in the joint;
Figure 5 is a side view of the joint;
Figure 6 shows a second embodiment of the joint;
Figure 7 is a side view of a girder with joints according to a third embodiment of the invention;
Figure 8 is a section on a larger scale on the line 8-8 in Figure 7 showing the chord without the struts;
Figure 9 is a section Oll the line 9-9 in Figure 8;
Figure 10 is the same section as in Figure 8 showing both the chord and the struts; and Figure 11 is a section on the line 11-11 in Figure 10.
. In Figure 1 is shown a side view of a girder 10 according to the invention comprisir.g chords or flanges 11 and 12 of wood and a web in the for,n . of inclined struts 13 of metal, suitably steel. The struts can be ~ubular or solid and they can form a continuous zig-zag sha-ped bar as shown in Figure 1.
Possible joints in this bar are placed at the places where the web is counter-sunk into the chords.
Figure 2 shows a separate chord 12 with recesses 15 for the struts 1~353~
13. ~igure :; shows in perspective a detail of how the bent portion 16 hetween two struts in a continuolls zig-zag bar 13 is inserted in a recess 15. Figure 4 sllo\Ys the same view as Figure 3 but with the joint filled with binding mat-erial 17.
Figure 5 shows in a side view how the curved intermediate portion 16 between ~wo struts in a continuous- zig-zag bar is placed at a certain depth below the upper surface of the upper chord 12, so that the binding material 17 covers the portion 16, which firstly improves the strength and secondly improves the heat insulation between the struts and the upper side of the girder. The same is of course also valid for the joints in the lower chord 11 in relation to the lower side thereof.
Figure 6 shows another embodiment of recess 20 where the top 21 of the recess lies below the upper surface of the chord 12. The recess 20 can suitably be machined with a shank-end mill, which can have a plane end or a rounded end depending on what shape the bottom of the recess 20 is supposed to have. The shape can suitably be the same as the shape of the strut, for instance a rounded bottom for a strut having a round section. The recess 15 can also be made with a shank-end mill or can alternatively be made with a straight saw.
Figures 7 to 11 show a further embodiment of the irlvention. The -view in Figure 7 is similar to the one in Figure 1 but the sections in Figures 8 to 11 are different. The reference numbers are also different. The girder 110 comprises a zig-zag bent bar 11 forming inclined struts 114 between two chords, one upper chord 112 and one lower chord 113. The bar 111 is bent in zig_zag form from a bar, a strip or similar and comprises straight portions 114, which form struts in the girder, and bent portions 115 which enter into recesses 116 in the chords.
Figure 8 shows the upper chord 112 in cross section on the line 9-9 S3~
in Figure 7 witll the bar lll re]novecl, and F:i.gure 9 shows the same po:rtion in longitlldillal secti.on on thc line 9-~ in Fi.gure 8. In ~igures 8 and 9 the bar lll has been removed in order to illustrate the recess 116 more clearly.
The web or strut bar 111 is attached to the chords 112 and 113 by inserting the cur~ed portions 115 into the recesses 116 and filling the space between the bar 111 and the recess 116 with a binding substance 117. The joint is illustrated in Figures 10 and ll with the recess 116 shown filled with the fastening substance which surrounds the curved portion and fills the recess 116 up to level with the inside 118 of the chord 112, and correspond-ingly for the lower chord 113. The fastening material in this case is also asuitable hardening and binding substance, for instance polyurethane plastics (resin) or epoxy glue.
In the embodiment in Figures 7 to il the recesses 116 are open only towards the inside of the chords and form a slit in the inside surface. The advantages of this are that as little as possible is removed from the wood in the chords, the pocket formed by the recess gives a firm fastening of the glue joint, and the pocket also forms a seat for the portion 115 which facilitates assembly of the components before applying the glue 117.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A girder of lattice type comprising an upper chord and a lower chord, said chords being of wood, and a web of metal con-sisting of a continuous bar, plate or the like bent to zig-zag form with alternating straight and bent portions, the straight portions forming struts between the chords and the bent portions being countersunk into recesses in the chords and fastened therein by a hardening and binding substance.
2. A girder as defined in claim 1, wherein the recesses in the chords are open on a lateral side of the chords.
3. A girder as defined in claim 1, wherein the recesses in the chords are open only on the inside of the chords.
4. Girder as defined in claim 1, 2 or 3, wherein the harden-ing and binding substance is polyurethane.
5. Girder as defined in claim 1, 2 or 3, wherein the harden-ing and binding substance is epoxy glue.
6. Girder as defined in claim 1, 2 or 3, wherein the web is made of steel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7901795-0 | 1979-02-28 | ||
| SE7901795A SE440676B (en) | 1979-02-28 | 1979-02-28 | BEAM |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1143534A true CA1143534A (en) | 1983-03-29 |
Family
ID=20337417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000346618A Expired CA1143534A (en) | 1979-02-28 | 1980-02-28 | Girder |
Country Status (8)
| Country | Link |
|---|---|
| AU (1) | AU536967B2 (en) |
| BE (1) | BE881973A (en) |
| CA (1) | CA1143534A (en) |
| ES (1) | ES255503Y (en) |
| FI (1) | FI800594A (en) |
| IT (1) | IT1140709B (en) |
| NO (1) | NO160092C (en) |
| SE (1) | SE440676B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1989011011A1 (en) * | 1988-05-04 | 1989-11-16 | Morris Nankin | Composite building element |
-
1979
- 1979-02-28 SE SE7901795A patent/SE440676B/en not_active IP Right Cessation
-
1980
- 1980-02-26 NO NO800538A patent/NO160092C/en unknown
- 1980-02-27 ES ES1980255503U patent/ES255503Y/en not_active Expired
- 1980-02-27 FI FI800594A patent/FI800594A/en not_active Application Discontinuation
- 1980-02-28 AU AU55965/80A patent/AU536967B2/en not_active Ceased
- 1980-02-28 IT IT20233/80A patent/IT1140709B/en active
- 1980-02-28 BE BE0/199592A patent/BE881973A/en unknown
- 1980-02-28 CA CA000346618A patent/CA1143534A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NO800538L (en) | 1980-08-29 |
| ES255503U (en) | 1981-05-16 |
| SE7901795L (en) | 1980-08-29 |
| IT8020233A0 (en) | 1980-02-28 |
| NO160092B (en) | 1988-11-28 |
| AU5596580A (en) | 1980-09-04 |
| FI800594A (en) | 1980-08-29 |
| ES255503Y (en) | 1981-11-16 |
| AU536967B2 (en) | 1984-05-31 |
| BE881973A (en) | 1980-08-28 |
| IT1140709B (en) | 1986-10-01 |
| NO160092C (en) | 1989-03-08 |
| SE440676B (en) | 1985-08-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |