CA2026929A1 - Chord truss roof structure - Google Patents
Chord truss roof structureInfo
- Publication number
- CA2026929A1 CA2026929A1 CA 2026929 CA2026929A CA2026929A1 CA 2026929 A1 CA2026929 A1 CA 2026929A1 CA 2026929 CA2026929 CA 2026929 CA 2026929 A CA2026929 A CA 2026929A CA 2026929 A1 CA2026929 A1 CA 2026929A1
- Authority
- CA
- Canada
- Prior art keywords
- ring
- chord
- tension
- members
- roof
- 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.)
- Abandoned
Links
Abstract
ABSTRACT OF THE DISCLOSURE
A chord truss roof includes a ring-girder, crossbeams arranged radially around the ring-girder, chord members stretched between the respective crossbeams and the ring-girder. The roof supports itself by tensioning the chord members. The ring-girder has an upper compression ring, a lower lension ring, and plural struts connecting the two rings. The chord members arranged opposite one another with both end portions of the tension ring interposed therebetween are connected to the corresponding end portions of the tension ring, and are joined to one another via connection members which are disposed between both end portions of the tension ring. Further, each strut is provided along a line which bisects the angle made by a corresponding chord member and the plane defined by the tension ring.
A chord truss roof includes a ring-girder, crossbeams arranged radially around the ring-girder, chord members stretched between the respective crossbeams and the ring-girder. The roof supports itself by tensioning the chord members. The ring-girder has an upper compression ring, a lower lension ring, and plural struts connecting the two rings. The chord members arranged opposite one another with both end portions of the tension ring interposed therebetween are connected to the corresponding end portions of the tension ring, and are joined to one another via connection members which are disposed between both end portions of the tension ring. Further, each strut is provided along a line which bisects the angle made by a corresponding chord member and the plane defined by the tension ring.
Description
202~29 C~-IORD TRUSS ROOF STRUCTURE
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a chord truss roof which is adapted to be stressed in a predetermined rnanner by tensioning its string or chord members to support itself with no strut provided in the center.
As one of the construction types of long span structure roofs, there is a chord truss roof structure.
Shown in Figs. 5 and 6 is an example of the structure of the chord truss roof as discussed in the above applications.
A roof 8 of the structure shown in Figs. 5 and 6 has an annular ring-girder which is generally denoted by reference numeral 1 in the figures. The ring girder 1 is composed of a compression ring 2 and a tension ring 3 which are respectively located at upper and lower positions in the ring-girder and joined to each other by struts 7.
Installed on the compression ring 2 is a roof light window 9.
Crossbeams 4 are radially arranged around the ring-girder 1 and respectively joined to the outer periphery thereof. Plural beams and braces are provided between and joined to adjacent crossbeams 4 and 4 to form a trussed roof. Furthermore, string or chord members 6 are stretched between outer ends 4a of the respective crossbeams 4 and the tension ring 3 at the bottom of the ring-girder 1. The chord members are tensioned to stress the roof structure. More particularly, the tensions acting on the respective chord members 6 cause forces f .... : ~, ~ ; .
.
~Q2~329 for pushing up the crossl)ealns 4; the forces are transmitted through the struts 7 to the crossbeams 4, so that the roof 8 can support itself.
Side wall sections 5 are separately constructed, and the roof 8 is laid on the side wall sections 5 with its outer ends 4a supported by upper end portions of tlle side wall sections. Incidentally, reference numeral 10 In Fig. 5 ~enotes seal portions which are provided inside the side wall sections.
The building having the roof 8 of this structure is constructed, for instance, in the procedure shown in Figs. 7 to 9.
First of all, as shown in Fig. 7, steel frames of the side wall sections 5 of the building are erected with cranes, and a working platform 11 for the ring-girder is assembled in approximately the center of the building. Then, the ring-girder 1 is assembled with the support by the working platform 11 as shown in Fig. 8. The ring-girder 1 is, for instance, of a circular shape as viewed from above, and the tension ring 3 is formed at the bottom of the ring-girder.
Subsequently, a skeleton or structural body work is executed on the steel frames with reinforced concrete. The crossbeams 4 are laid one after another with the cranes between the upper end portions of the side wall sections 5 and the ring-girder to be assembled in an arcuate shape as viewed from the side and in a circular shape as viewed from above. The beams, braces and so forth are installed to form the chord truss roof.
After the above work, the chord members 6 are installed between the respective outer ends 4a of the crossbeams 4 and the tension ring 3 at the bottom of the ring-girder 1, as shown in Fig. 9.
.
- - -~02~2~
Subsequently, the cllord members 6 are tensioned to exert a required stress on the trussed roof thus assembled, so that the trussed roof can support itself. The cllord truss roof 8 is thus completed, and the working platform 11 is removed.
In addiUon, arter the tensioning, roofing materials, etc. are installed by a(:lhesion over tlle chord truss roof 8, and finish works, such as a waterproofing worl~ and so on, are performed to complete the whole work.
However, in the chord truss roof 8 of the above structure, the chord members 6 on the both sides of the ring-girder 1 are continuous so that each extends across the ring-girder 1 from the outer end 4a of one crossbeam 4 to the outer end 4a of an opposite crossbeam 4. In the case of the chord truss roof 8 of a large size, therefore, each chord member 6 also becomes long accordingly and, when tensioning the chord member 6, a jack which is a means for tensioning has to have a surficiently long stroke. For this reason, it is necessary when tensioning the chord members 6 to provide jacks of large sizes. Improvement of the structure in this respect has been desired. Additionally, since the tension ring 3 at the bottom of the ring-girder 1 is subjected to forces for inwardly thrusting the same due to the tensioning of the chord members 6, the tension ring 3 needs reinforcing.
SUMMA~Y OF THE INVENTION
It is an object of the invention to provide a chord truss roof structure which can readily be stressed with,jacks of relatively short 2 ~ 2 9 stroke.
It is another object of the invention to provide a chord truss roof ~,vhich is reinforced in its tension ring while involving less increase in weight.
Still another object of Lhe invention is to provide a chord truss roof structure wherein tension applied to each chord member thereof is effectively transmitted to a corresponding crossbeam so that the tension to be applied to the chord member per se can be reduced.
For the above ends, according to one aspect of the invention, there is provided a chord truss roof structure which comprises a pair of girders which extend in parallel respectively, plural crossbeams arranged outwardly around the girders and ~oined thereto, plural beams and braces arranged between and Joined to adjacent crossbeams to form a trussed roof, and chord members stretched between outer ends of the respective crossbeams and the respective girders to apply required stress to the trussed roof. The chord members are disposed between outer ends of the respective crossbeams and one of the girders~oined thereto, and ends of the chord members arranged oppsitely on the girder side are ~oined to one another by connection members.
With the above structure of the chord truss roof, the length of each chord member can be reduced to less than half as cornpared with the continuous chord member which has been used hitherto.
Accordingly, the required stroke of a jack for tensioning each chord mernber may be short, and a large jack is unnecessary. Further, by respectively disposing the chord members on both sides of the ~ . , ' ~
- 2~2~2~
girders, or as a result of the chord members being divided by the girders, it becomes easy to apply stress to the roof in a balanced manner by means of the chord members. ~urthermore, as the ends of the chord members on the girder side are connected to one another by the connection mcmbers, the girders are, so to speak. in a state of being connected to each other by the connection members.
Therefore, the stress applied to the chord members is smoothly and effectively transmitted to the girders, and it becomes possible to rationally design the roof.
According to another aspect of the invention, there is provided a chord truss roof comprising a ring-girder which has compression and tension rings respectively located at upper and lower positions of the ring-girder and ~oined to each other by struts, crossbeams radially provided around the compression ring of the ring-girder, and chord members each stretched under predetermined tension between the crossbeams and the tension ring, wherein each strut of the rlng-girder is provided to stand substanLially along a segment of a line which bisects an angle made by a corresponding chord member and a plane in which the tension ring is provided.
Herein, the plane in which the tension ring is provided means a plane including an imaginary ring which is deflned by connecting joints of the respective chord lllembers and the tension ring.
With the roof structure according to the second aspect of the invention, as each strut of the ring-girder is provided along the line segment which bisects the angle made by a corresponding chord member and the plane in which the tension ring is provided, the direction of a resultant l`orce rrolll the tensions respectively acting on the tension ring ancl the chor(l melllber coincides with the direction in which the strut is provided. As a result, according to the chord truss roof structure of this aspect, the tension applied to each chord member is erfectively transmilted as a force for pushing up the roof to a corresponding crossbeam. Accordingly, the tension to be applied to each chord l~ember for allowing the roof to support itself can be lessened.
Moreover, as the direc~ion of the resultant force from the tensions respectively acting on the tension ring and each chord member coincides with the direction in which a corresponding strut is provided, the load on the strut acts in the axial direction thereof.
Accordingly, no lateral load due to the tension applied to the chord member acts on the strut, and the load on the strut can be reduced.
BRIEF DESCRIPI'ION OF THE DRAWINGS
Fig. 1 is a sectional view of a chord truss roof according to an embodiment of the invention and shows an enlargement of a chord member and a connection member thereof.
Fig. 2 is a schematic perspective view of the chord truss roof shown in Fig. 1.
Fig. 3 is a sectional side view showing an essential portion of a chord truss roof structure according to another embodiment of the invention.
Fig. 4 is a view showing the direction of a force caused in the roof shown in Fig. 3 under a condition that chord members thereof are - 2~929 tensioned .
Figs. 5 and 6 sho~v a conventional chord truss roof structure, Fig. 5 is a sectional side view of the structure and Fig. 6 is a schematic perspective view thereof as vie~,ved from above.
Fig. 7 is a schematic vie~,v showing a state of a working platform assernbled when constructing a string beam roof.
Fig. 8 is a schemal:ic view showing a state of installation of a ring-girder and crossbeams during the construction of the roof shown in Fig. 7.
Fig. 9 is a schematic view showing a completed state of the roof shown in Fig. 7.
DETAILED DESCRIPI'ION OF THE PREFERRED EMBODIMENTS
Descriptions ~,vill now be of embodiments of the invention with reference to the accompanying drawings, In the following description, identical reference numerals denote corresponding or the sa~ne constituent elements as those of the roof described above with reference to Figs. 5 to 9, and description on them will be omitted for brevity.
Fig. 1 is a vie~,v showing a chord truss roof structure according to the flrst embodiment of the invention. As shown in Fig. 2, a ring-girder 1 of this embodiment is formed in an elliptical shape as viewed from above, and the roof 8 as a whole is also formed in an elliptical shape.
The roof of this embodiment is reatured in that each chord member, which has been one continuous element hitherto, is divided into two, wilh a tension ring 3 interposed therebetweell and the thus divided chord members 16 are joined to the tension ring 3, respectively. Further, the ends of the divided chord members 16, which lie opposite one anotller at straight portions or girders of the tension ring 3 are connected to one anther by connecting members 20 of H-seciiol1 steel.
An arbitrary method may be used for connecting the chord members 16 to the tension rillg 3. For instancc, when the chord member 16 is made of a linear material such as a wire and so forth, the chord member 16 can be connected at its one end to the tension ring 3 by a bolt fastening means, or the like.
According to this embodiment, the length of each chord member 16 can be reduced to less than half in comparison with the case where a continuous chord member is used as is in the conventional roof structure. Therefore, the required stroke of a Jack for tensioning each chord member 16 may be relatively short, and a large ~ack is unnecessary. Furthermore, when using the continuous chord members 6 as in the case of the conventional roof structure, saddle portions are provided on the tension ring 3 to allow the chord members 6 to bend ancl pass over the tension ring. In this case, there is a possibility that the friction at the saddle portions will unbalance the tension applied to each chord member on both sides of the tension ring 3. In contrast to this conventional roof structure, thanks to the chord members 16 divided on both sides of the tension ring 3, the above embodiment of the invention makes it possible to readily apply stress to the roof structure in a well balanced manner by means . .
.
~ . .
~2~923 g of the chord melllbels 16.
Moreover, in the described embodin1ent, the ends of the chord members 16 011 Lhe tcnsiol1 ring 3 side are connected to one another by the H-secl:ion ste~l melllbers 20; in other words, the straight portions of the tension ring 3 are in a state of being connected to each other by the lI-section steel members 20. Accordingly, even when the straight portions of the tension ring 3 are subjected to the forces for inwardly thrusting lhelll due to the tensioning of the chord members 16, the H- section steel members 20 selve for reinforcement of the tension ring 3 and for allowing the forces acting on one of the straight portions to be smoothly transmitted to the other straight portion, As a result, the stress applied to the chord members 16 is smoothly and effectively transmitted to the tension ring 3, and a rational design of the roof structure becomes possible.
Fig. 3 shows an essential portion of a string beam roof according to another embodiment of the invention. The chord truss roof of the second embodiment is designed in view of another problem in the conventional chord truss roof.
Namely, in the conventional chord truss roof structure, as shown in Fig. 5, each strut 7 of the ring- girder 1 is provided to stand vertically with respect to a plane A which is defined by the tension ring 3. This structure, however, requires a large tension to be applied to each chord men1ber to allow the roof 8 to support itself, and is unsatisfactoly in that the chord members are subjected to the large load.
The roof structure shown in Fig. 3 is in a state in which it is ~2~2~
supporting itself. ~n the figure, reference n~lmeral 21 generally denotes a ring-girder. The ring-girder 21, as in the ring-girder 1 of the first embodimcnt, is composed of a compression ring 22 and a tension ring 23 which are respectively located at upper and lower positions in the ring-girder and joined to each other by means of struts 27, The tension ring 23 of the ring-girder 21 of this embodiment, however, is formed slightly larger in si~e than the compression ring 22. Each strut 27 of the ring-girder 21 is provided along a segment D of a line which bisects an angle C made by a corresponding chord member 16 and the plane A. The plane A
includes an imaginary ring whicll is defined by connecting joints 24 of the tension ring 23 and the respective chord members 16, and will be ~eferred to in the following description as the plane in which the tension ring 23 is provided.
Around the compression ring 22 of the ring-girder 21, crossbeams 4 are radially provided. Each crossbeam 4 is a latticed beam structure which is composed of an upper chord member 25, a lower chord member 26 and lattice members 28. Adjacent crossbeams 4 and 4 are joined to each other by means of braces and beams (not shown). One end of each chord member 16 is connected to a corresponding crossbeam 4 at an outer end 4a thereof through a bracket 29. The other end of the chord member 16 is connected to the tension ring 23.
In the chord truss roof structure of this embodiment, each strut 27 of the ring-girder 21 is provided along the line segment D which bisects the angle C made by a corresponding chord member 16 and .
, . :
. , .
: .
2 ~ 2 ~
the plane A in which the tension ring 23 is provided. Therefore, as shown in Fig. 4, the direction of a resultant force F from the tensions Pl and P2 respectively acting on the tension ring 23 and the chord member 16 coincides ~,vith the clireclion in which the strut 27 is provided. Ii`or this reason, according to the chord truss roof structure, the tension applie(i Lo eacll chord melllber is effectively transmitted as the pushing up force F to a corresponding crossbeam 4. With this chord truss roof structure. thererore, the tension to be applïed to each chord member for letting the roof support itself can be reduced.
Moreover, in the chord truss roof structure of this embodiment, as described above, the direction of the resultant force F from the tensions Pl and P2 respectively acting on the tension ring 23 and each chord member 16 coincides with the direction in which a corresponding sh-ut 27 is provided. This means that the load on the strut 27 acts in the axial direction thereof. According to this chord truss roof structure, therefore, no lateral load caused by the tension applied to each chord member acts on a corresponding strut 27, and the load on the strut 27 can be lessened.
Although the chord truss roof of the invention has been described on the basis of the specific forms of the embodiments, the details of the roof structure of the invention are not limited solely to the described embodiments, and various modifications way be made.
For example, although the trussed roof has been described in the embodiments to be formed in an arcuate shape as viewed from the side, it may also be formed as a gable roof. Further, the description of the first embodiment has been made that the H-section steel members join the ends of the chord members to one another, which face one another at the straight portions of the tension ring 3.
However, it is a mat~er of course that the H-section steel members 20 may be arranged obliquely, like braces, with respect to the straight portions of the tension ring. Iiurthermore, although these H-section steel members 20 are used as connection members in the above embodiment, other kllo~,vll members also may suitably be used to this end. Moreover, although In the embodiments the trussed roof has been described to be formed in an elliptical shape, the chor;i truss roof of the invention is applicable to any shape of roof, e.g., a rectangular shape, etc.
, ~
' ~ "
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a chord truss roof which is adapted to be stressed in a predetermined rnanner by tensioning its string or chord members to support itself with no strut provided in the center.
As one of the construction types of long span structure roofs, there is a chord truss roof structure.
Shown in Figs. 5 and 6 is an example of the structure of the chord truss roof as discussed in the above applications.
A roof 8 of the structure shown in Figs. 5 and 6 has an annular ring-girder which is generally denoted by reference numeral 1 in the figures. The ring girder 1 is composed of a compression ring 2 and a tension ring 3 which are respectively located at upper and lower positions in the ring-girder and joined to each other by struts 7.
Installed on the compression ring 2 is a roof light window 9.
Crossbeams 4 are radially arranged around the ring-girder 1 and respectively joined to the outer periphery thereof. Plural beams and braces are provided between and joined to adjacent crossbeams 4 and 4 to form a trussed roof. Furthermore, string or chord members 6 are stretched between outer ends 4a of the respective crossbeams 4 and the tension ring 3 at the bottom of the ring-girder 1. The chord members are tensioned to stress the roof structure. More particularly, the tensions acting on the respective chord members 6 cause forces f .... : ~, ~ ; .
.
~Q2~329 for pushing up the crossl)ealns 4; the forces are transmitted through the struts 7 to the crossbeams 4, so that the roof 8 can support itself.
Side wall sections 5 are separately constructed, and the roof 8 is laid on the side wall sections 5 with its outer ends 4a supported by upper end portions of tlle side wall sections. Incidentally, reference numeral 10 In Fig. 5 ~enotes seal portions which are provided inside the side wall sections.
The building having the roof 8 of this structure is constructed, for instance, in the procedure shown in Figs. 7 to 9.
First of all, as shown in Fig. 7, steel frames of the side wall sections 5 of the building are erected with cranes, and a working platform 11 for the ring-girder is assembled in approximately the center of the building. Then, the ring-girder 1 is assembled with the support by the working platform 11 as shown in Fig. 8. The ring-girder 1 is, for instance, of a circular shape as viewed from above, and the tension ring 3 is formed at the bottom of the ring-girder.
Subsequently, a skeleton or structural body work is executed on the steel frames with reinforced concrete. The crossbeams 4 are laid one after another with the cranes between the upper end portions of the side wall sections 5 and the ring-girder to be assembled in an arcuate shape as viewed from the side and in a circular shape as viewed from above. The beams, braces and so forth are installed to form the chord truss roof.
After the above work, the chord members 6 are installed between the respective outer ends 4a of the crossbeams 4 and the tension ring 3 at the bottom of the ring-girder 1, as shown in Fig. 9.
.
- - -~02~2~
Subsequently, the cllord members 6 are tensioned to exert a required stress on the trussed roof thus assembled, so that the trussed roof can support itself. The cllord truss roof 8 is thus completed, and the working platform 11 is removed.
In addiUon, arter the tensioning, roofing materials, etc. are installed by a(:lhesion over tlle chord truss roof 8, and finish works, such as a waterproofing worl~ and so on, are performed to complete the whole work.
However, in the chord truss roof 8 of the above structure, the chord members 6 on the both sides of the ring-girder 1 are continuous so that each extends across the ring-girder 1 from the outer end 4a of one crossbeam 4 to the outer end 4a of an opposite crossbeam 4. In the case of the chord truss roof 8 of a large size, therefore, each chord member 6 also becomes long accordingly and, when tensioning the chord member 6, a jack which is a means for tensioning has to have a surficiently long stroke. For this reason, it is necessary when tensioning the chord members 6 to provide jacks of large sizes. Improvement of the structure in this respect has been desired. Additionally, since the tension ring 3 at the bottom of the ring-girder 1 is subjected to forces for inwardly thrusting the same due to the tensioning of the chord members 6, the tension ring 3 needs reinforcing.
SUMMA~Y OF THE INVENTION
It is an object of the invention to provide a chord truss roof structure which can readily be stressed with,jacks of relatively short 2 ~ 2 9 stroke.
It is another object of the invention to provide a chord truss roof ~,vhich is reinforced in its tension ring while involving less increase in weight.
Still another object of Lhe invention is to provide a chord truss roof structure wherein tension applied to each chord member thereof is effectively transmitted to a corresponding crossbeam so that the tension to be applied to the chord member per se can be reduced.
For the above ends, according to one aspect of the invention, there is provided a chord truss roof structure which comprises a pair of girders which extend in parallel respectively, plural crossbeams arranged outwardly around the girders and ~oined thereto, plural beams and braces arranged between and Joined to adjacent crossbeams to form a trussed roof, and chord members stretched between outer ends of the respective crossbeams and the respective girders to apply required stress to the trussed roof. The chord members are disposed between outer ends of the respective crossbeams and one of the girders~oined thereto, and ends of the chord members arranged oppsitely on the girder side are ~oined to one another by connection members.
With the above structure of the chord truss roof, the length of each chord member can be reduced to less than half as cornpared with the continuous chord member which has been used hitherto.
Accordingly, the required stroke of a jack for tensioning each chord mernber may be short, and a large jack is unnecessary. Further, by respectively disposing the chord members on both sides of the ~ . , ' ~
- 2~2~2~
girders, or as a result of the chord members being divided by the girders, it becomes easy to apply stress to the roof in a balanced manner by means of the chord members. ~urthermore, as the ends of the chord members on the girder side are connected to one another by the connection mcmbers, the girders are, so to speak. in a state of being connected to each other by the connection members.
Therefore, the stress applied to the chord members is smoothly and effectively transmitted to the girders, and it becomes possible to rationally design the roof.
According to another aspect of the invention, there is provided a chord truss roof comprising a ring-girder which has compression and tension rings respectively located at upper and lower positions of the ring-girder and ~oined to each other by struts, crossbeams radially provided around the compression ring of the ring-girder, and chord members each stretched under predetermined tension between the crossbeams and the tension ring, wherein each strut of the rlng-girder is provided to stand substanLially along a segment of a line which bisects an angle made by a corresponding chord member and a plane in which the tension ring is provided.
Herein, the plane in which the tension ring is provided means a plane including an imaginary ring which is deflned by connecting joints of the respective chord lllembers and the tension ring.
With the roof structure according to the second aspect of the invention, as each strut of the ring-girder is provided along the line segment which bisects the angle made by a corresponding chord member and the plane in which the tension ring is provided, the direction of a resultant l`orce rrolll the tensions respectively acting on the tension ring ancl the chor(l melllber coincides with the direction in which the strut is provided. As a result, according to the chord truss roof structure of this aspect, the tension applied to each chord member is erfectively transmilted as a force for pushing up the roof to a corresponding crossbeam. Accordingly, the tension to be applied to each chord l~ember for allowing the roof to support itself can be lessened.
Moreover, as the direc~ion of the resultant force from the tensions respectively acting on the tension ring and each chord member coincides with the direction in which a corresponding strut is provided, the load on the strut acts in the axial direction thereof.
Accordingly, no lateral load due to the tension applied to the chord member acts on the strut, and the load on the strut can be reduced.
BRIEF DESCRIPI'ION OF THE DRAWINGS
Fig. 1 is a sectional view of a chord truss roof according to an embodiment of the invention and shows an enlargement of a chord member and a connection member thereof.
Fig. 2 is a schematic perspective view of the chord truss roof shown in Fig. 1.
Fig. 3 is a sectional side view showing an essential portion of a chord truss roof structure according to another embodiment of the invention.
Fig. 4 is a view showing the direction of a force caused in the roof shown in Fig. 3 under a condition that chord members thereof are - 2~929 tensioned .
Figs. 5 and 6 sho~v a conventional chord truss roof structure, Fig. 5 is a sectional side view of the structure and Fig. 6 is a schematic perspective view thereof as vie~,ved from above.
Fig. 7 is a schematic vie~,v showing a state of a working platform assernbled when constructing a string beam roof.
Fig. 8 is a schemal:ic view showing a state of installation of a ring-girder and crossbeams during the construction of the roof shown in Fig. 7.
Fig. 9 is a schematic view showing a completed state of the roof shown in Fig. 7.
DETAILED DESCRIPI'ION OF THE PREFERRED EMBODIMENTS
Descriptions ~,vill now be of embodiments of the invention with reference to the accompanying drawings, In the following description, identical reference numerals denote corresponding or the sa~ne constituent elements as those of the roof described above with reference to Figs. 5 to 9, and description on them will be omitted for brevity.
Fig. 1 is a vie~,v showing a chord truss roof structure according to the flrst embodiment of the invention. As shown in Fig. 2, a ring-girder 1 of this embodiment is formed in an elliptical shape as viewed from above, and the roof 8 as a whole is also formed in an elliptical shape.
The roof of this embodiment is reatured in that each chord member, which has been one continuous element hitherto, is divided into two, wilh a tension ring 3 interposed therebetweell and the thus divided chord members 16 are joined to the tension ring 3, respectively. Further, the ends of the divided chord members 16, which lie opposite one anotller at straight portions or girders of the tension ring 3 are connected to one anther by connecting members 20 of H-seciiol1 steel.
An arbitrary method may be used for connecting the chord members 16 to the tension rillg 3. For instancc, when the chord member 16 is made of a linear material such as a wire and so forth, the chord member 16 can be connected at its one end to the tension ring 3 by a bolt fastening means, or the like.
According to this embodiment, the length of each chord member 16 can be reduced to less than half in comparison with the case where a continuous chord member is used as is in the conventional roof structure. Therefore, the required stroke of a Jack for tensioning each chord member 16 may be relatively short, and a large ~ack is unnecessary. Furthermore, when using the continuous chord members 6 as in the case of the conventional roof structure, saddle portions are provided on the tension ring 3 to allow the chord members 6 to bend ancl pass over the tension ring. In this case, there is a possibility that the friction at the saddle portions will unbalance the tension applied to each chord member on both sides of the tension ring 3. In contrast to this conventional roof structure, thanks to the chord members 16 divided on both sides of the tension ring 3, the above embodiment of the invention makes it possible to readily apply stress to the roof structure in a well balanced manner by means . .
.
~ . .
~2~923 g of the chord melllbels 16.
Moreover, in the described embodin1ent, the ends of the chord members 16 011 Lhe tcnsiol1 ring 3 side are connected to one another by the H-secl:ion ste~l melllbers 20; in other words, the straight portions of the tension ring 3 are in a state of being connected to each other by the lI-section steel members 20. Accordingly, even when the straight portions of the tension ring 3 are subjected to the forces for inwardly thrusting lhelll due to the tensioning of the chord members 16, the H- section steel members 20 selve for reinforcement of the tension ring 3 and for allowing the forces acting on one of the straight portions to be smoothly transmitted to the other straight portion, As a result, the stress applied to the chord members 16 is smoothly and effectively transmitted to the tension ring 3, and a rational design of the roof structure becomes possible.
Fig. 3 shows an essential portion of a string beam roof according to another embodiment of the invention. The chord truss roof of the second embodiment is designed in view of another problem in the conventional chord truss roof.
Namely, in the conventional chord truss roof structure, as shown in Fig. 5, each strut 7 of the ring- girder 1 is provided to stand vertically with respect to a plane A which is defined by the tension ring 3. This structure, however, requires a large tension to be applied to each chord men1ber to allow the roof 8 to support itself, and is unsatisfactoly in that the chord members are subjected to the large load.
The roof structure shown in Fig. 3 is in a state in which it is ~2~2~
supporting itself. ~n the figure, reference n~lmeral 21 generally denotes a ring-girder. The ring-girder 21, as in the ring-girder 1 of the first embodimcnt, is composed of a compression ring 22 and a tension ring 23 which are respectively located at upper and lower positions in the ring-girder and joined to each other by means of struts 27, The tension ring 23 of the ring-girder 21 of this embodiment, however, is formed slightly larger in si~e than the compression ring 22. Each strut 27 of the ring-girder 21 is provided along a segment D of a line which bisects an angle C made by a corresponding chord member 16 and the plane A. The plane A
includes an imaginary ring whicll is defined by connecting joints 24 of the tension ring 23 and the respective chord members 16, and will be ~eferred to in the following description as the plane in which the tension ring 23 is provided.
Around the compression ring 22 of the ring-girder 21, crossbeams 4 are radially provided. Each crossbeam 4 is a latticed beam structure which is composed of an upper chord member 25, a lower chord member 26 and lattice members 28. Adjacent crossbeams 4 and 4 are joined to each other by means of braces and beams (not shown). One end of each chord member 16 is connected to a corresponding crossbeam 4 at an outer end 4a thereof through a bracket 29. The other end of the chord member 16 is connected to the tension ring 23.
In the chord truss roof structure of this embodiment, each strut 27 of the ring-girder 21 is provided along the line segment D which bisects the angle C made by a corresponding chord member 16 and .
, . :
. , .
: .
2 ~ 2 ~
the plane A in which the tension ring 23 is provided. Therefore, as shown in Fig. 4, the direction of a resultant force F from the tensions Pl and P2 respectively acting on the tension ring 23 and the chord member 16 coincides ~,vith the clireclion in which the strut 27 is provided. Ii`or this reason, according to the chord truss roof structure, the tension applie(i Lo eacll chord melllber is effectively transmitted as the pushing up force F to a corresponding crossbeam 4. With this chord truss roof structure. thererore, the tension to be applïed to each chord member for letting the roof support itself can be reduced.
Moreover, in the chord truss roof structure of this embodiment, as described above, the direction of the resultant force F from the tensions Pl and P2 respectively acting on the tension ring 23 and each chord member 16 coincides with the direction in which a corresponding sh-ut 27 is provided. This means that the load on the strut 27 acts in the axial direction thereof. According to this chord truss roof structure, therefore, no lateral load caused by the tension applied to each chord member acts on a corresponding strut 27, and the load on the strut 27 can be lessened.
Although the chord truss roof of the invention has been described on the basis of the specific forms of the embodiments, the details of the roof structure of the invention are not limited solely to the described embodiments, and various modifications way be made.
For example, although the trussed roof has been described in the embodiments to be formed in an arcuate shape as viewed from the side, it may also be formed as a gable roof. Further, the description of the first embodiment has been made that the H-section steel members join the ends of the chord members to one another, which face one another at the straight portions of the tension ring 3.
However, it is a mat~er of course that the H-section steel members 20 may be arranged obliquely, like braces, with respect to the straight portions of the tension ring. Iiurthermore, although these H-section steel members 20 are used as connection members in the above embodiment, other kllo~,vll members also may suitably be used to this end. Moreover, although In the embodiments the trussed roof has been described to be formed in an elliptical shape, the chor;i truss roof of the invention is applicable to any shape of roof, e.g., a rectangular shape, etc.
, ~
' ~ "
Claims (6)
1. A chord truss roof structure comprising a pair of girders which extend in parallel respectively, plural crossbeams arranged outwardly from said girders and joined thereto, plural beams and braces arranged between and joined to adjacent crossbeams to form a trussed roof, and chord members stretched between outer ends of the respective crossbeams and the respective girders to apply required stress to said trussed roof, wherein said chord members are disposed between outer ends of the respective crossbeams and one of the girders joined thereto, and ends of said chord members arranged oppositely on the girder side are joined to one another by connection members.
2. The structure according to claim 1, wherein each of said connection members is made of H-beam.
3. The structure according to claim 1, wherein each of said girders comprises of a upper compression member joined to said crossbeams thereto, and a lower tension member joined to said chord members thereto, and wherein said compression member and said tension member are joined to each other by struts.
4. The structure according to claim 1, wherein said pair of girders are connected by forming members so as to be assembled in an elliptical shape as viewed from above, and the roof structure as a whole is also of a substantially elliptical shape as viewed from above.
5. The structure according to claim 3, wherein each of said girders comprises of a upper compression member joined to said crossbeams thereto, and a lower tension member joined to said chord members thereto, and wherein said compression member and said tension member are joined to each other by struts.
6. The structure according to claim 3, wherein each of said struts is provided to stand substantially along a segment of a line which bisects an angle made by a corresponding chord member and a plane in which said tension members is provided. 7. A chord truss roof comprising a ring-girder, said ring-girder having compression and tension rings respectively located at upper and lower position in said ring-girder and joined to each other by struts, crossbeams radially provided around said compression ring of the ring-girder, and chord members each stretched under predetermined tension between said crossbeams and said tension ring, wherein each of said struts is provided to stand substantially along a segment of a line which bisects an angle made by a corresponding chord member and a plane in which said tension ring is provided.
8. The roof according to claim 7, wherein said tension ring are formed larger in size than said compression ring so that said struts are respectively inclined with respect to the plane in which said tension ring is provided.
9. The roof according to claim 7, wherein said ring-girders is formed in an elliptical shape as viewed from above, and the roof structure as a whole is also of a substantially elliptical shape as viewed from above.
10. The roof according to claim 9, further comprising connecting members which are disposed between straight portion of said tension ring of the elliptical shape. said connection members joining opposite chord members connecting to the respective straight portions of said tension ring.
11. The roof according to claim 10, wherein each of said connection member is made of H-section steel.
8. The roof according to claim 7, wherein said tension ring are formed larger in size than said compression ring so that said struts are respectively inclined with respect to the plane in which said tension ring is provided.
9. The roof according to claim 7, wherein said ring-girders is formed in an elliptical shape as viewed from above, and the roof structure as a whole is also of a substantially elliptical shape as viewed from above.
10. The roof according to claim 9, further comprising connecting members which are disposed between straight portion of said tension ring of the elliptical shape. said connection members joining opposite chord members connecting to the respective straight portions of said tension ring.
11. The roof according to claim 10, wherein each of said connection member is made of H-section steel.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-261523 | 1989-10-06 | ||
| JP1-261622 | 1989-10-06 | ||
| JP26152389A JP2901284B2 (en) | 1989-10-06 | 1989-10-06 | Overcurrent protection circuit |
| JP1261622A JPH0811900B2 (en) | 1989-10-06 | 1989-10-06 | Structure of beam string roof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2026929A1 true CA2026929A1 (en) | 1991-04-07 |
Family
ID=26545114
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2026929 Abandoned CA2026929A1 (en) | 1989-10-06 | 1990-10-04 | Chord truss roof structure |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2026929A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102587497A (en) * | 2012-03-21 | 2012-07-18 | 中国民航大学 | String truss structure with load-relieving effect and implementation method |
-
1990
- 1990-10-04 CA CA 2026929 patent/CA2026929A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102587497A (en) * | 2012-03-21 | 2012-07-18 | 中国民航大学 | String truss structure with load-relieving effect and implementation method |
| CN102587497B (en) * | 2012-03-21 | 2014-02-26 | 中国民航大学 | String truss structure with load-relieving effect and implementation method |
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