JP2617856B2 - Composite lattice beam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite lattice beam, and more particularly to a composite lattice beam prestressed by a tension cable.

[0002]

2. Description of the Related Art Conventionally, a truss beam is generally used as a structural beam because it is composed of a connection body of a large number of triangular frame members and has high rigidity and is advantageous in terms of stress. Recently, however, composite truss beams incorporating a tension cable for applying prestress to truss beams are being put to practical use (see, for example, JP-A-62-182343 and JP-A-1-190845). On the other hand, a lattice beam composed of a connected body of quadrangular frame elements is low in rigidity because it has no lattice material, is easily deformed, and is disadvantageous in terms of stress. Therefore, it is practically used as a beam for an actual structure. However, no technique for applying prestress to the lattice beam has been proposed at all. by the way,
For beams of large span structures such as recent movable hangars, movable roofs of sports facilities, factory buildings, event facilities, etc., it is important to reduce the amount of flexure. Is being requested.

[0003]

In a truss beam having a large span, stress and flexural deformation due to its own weight are large.
It is necessary to increase the height of the beam, a large number of lattice members are required, and the number of members increases. For the purpose of solving this, a composite truss beam in which a prestress is added to the truss beam is being put into practical use,
Because truss beams are rigid and difficult to deform, it is not very advantageous to apply prestress to the truss beams to control the stress and deformation, and it is not very advantageous in terms of cost-effectiveness of introducing prestress.

[0004] In the composite truss beam to which the prestress has been added, although the beam height can be reduced somewhat, the above-mentioned drawbacks still remain basically. The ratio of the bending stiffness of the
There is a problem that the required tension is increased and the stress is not severe, so that there is little room for applying high-tensile steel, and there is a lack of design freedom to reduce the weight of the steel material in order to reduce the manufacturing cost. Since the lattice beam has low rigidity and large bending deformation, it is almost impossible to apply a conventionally known simple lattice beam to a large span structure. SUMMARY OF THE INVENTION It is an object of the present invention to provide a composite grid beam incorporating a tension cable that prestresses the grid beam.

[0005]

According to a first aspect of the present invention, a composite lattice beam includes one or more upper chords, one or more lower chords, and a plurality of bundles connecting the upper and lower chords. It is a lattice beam configured as the main body, and the part near both ends is
A lattice beam formed by providing a lattice material, its rating to the grid beam
And a tension cable for applying a prestress to suppress downward flexural deformation of the subsidiary beam . A composite lattice beam according to a second aspect is the composite lattice beam according to the first aspect, wherein the lattice beam is a plane lattice beam having one upper chord member and one lower chord member. The composite lattice beam of claim 3 is claim 1.
In the composite lattice beam of the above, the lattice beam comprises two upper chord members and 2
It is a three-dimensional lattice beam having two lower chord members.

The composite lattice beam of claim 4 is the composite lattice beam of claim 2 or 3 , wherein the tension is applied to the lattice beam.
Which was provided <br/> sub tension cable which is disposed so as compared to the prestressing of the cables to a small enough prestress adding suppress prestress the bending deformation of the upper lattice girder is there.

[0007]

In the composite lattice beam according to the first aspect, one or more upper chords, one or more lower chords, and a plurality of bundles connecting the upper chords and the lower chord are mainly constituted. Lattice material is provided at the part near both ends of the lattice beam
And a downward bending of the lattice beam to the lattice beam
Since it has a tension cable that adds pre-stress to suppress deformation, the tension cable does not compensate the weakness of the lattice beam that the amount of downward bending increases, and a rational composite lattice that utilizes the advantages of the lattice beam. A beam is obtained. That is, since the rigidity ratio of the lattice beam is small, the prestress introduction efficiency is high, and the bending deformation of the lattice beam can be effectively suppressed with a significantly smaller tension force than in the case of the truss beam. In other words, the tension cable achieves a prestress introduction function and a suspension function for suspending and supporting the lattice beam.

Deflection deformation of a lattice beam in the downward direction by a tension cable
By adding the inhibiting prestress the lower grid beam
Since the bending deformation can be suppressed, the design based on the stress can be performed instead of the design based on the rigidity. Therefore, it is possible to reduce the weight of the steel material by applying the high-tensile steel. Lattice beams have a lower rigidity than truss beams, so by appropriately setting the prestress added with tension cables and the material of the lattice beams, even a beam with a large span will have a relatively small beam profile. It can be a lattice beam. Since a large number of lattice materials can be omitted in the lattice beam, the manufacturing cost associated with processing and welding of a large number of lattice materials can be significantly reduced. However, a lattice material is used near the both ends of the lattice beam.
Is provided, so that the relative size generated near the both ends is large.
A large bending moment can be reduced.

A composite lattice beam according to claim 2 is the plane lattice beam according to claim 1, wherein the lattice beam has one upper chord member and one lower chord member, which is suitable for a beam having a relatively small span. It is also applicable to large span beams. Claim 3
The composite lattice beam according to claim 1, wherein the lattice beam is a three-dimensional lattice beam having two upper chord members and two lower chord members, which is suitable for a beam having a relatively large span, but a beam having a small span. Is also applicable.

According to a fourth aspect of the present invention, there is provided a composite lattice beam according to the second or third aspect , wherein the tension beam is attached to the lattice beam.
It is provided with the sub-tension cable that a sufficient small prestress compared to prestressing Bull adding suppress prestress the bending deformation of the upper lattice girder, deformed by the main tensioning cable down the lattice girder It is possible to suppress the displacement and to suppress the displacement of the lattice beam to the upper side due to the wind load due to the auxiliary tension cable.

[0011]

As described in the section of the operation, according to the composite lattice beam of the present invention, the following effects can be obtained. According to the composite lattice beam of claim 1, the lattice beam and the lattice beam are provided below the composite lattice beam.
Since it is equipped with a tension cable that applies prestress that suppresses bending deformation to the bottom, the tension cable does not compensate for the weakness of the lattice beam that the amount of downward bending becomes large, and it is rational utilizing the advantages of the lattice beam. A complex composite lattice beam can be obtained. That is, the flexural deformation of the lattice beam can be effectively suppressed with a significantly smaller tension than in the case of the truss beam, and the prestress introduction function and the suspension function of suspending and supporting the lattice beam can be achieved by the tension cable. Tension cables can suppress the bending deformation of the lattice beam, enabling a stress-based design instead of a rigid-based design, making it possible to use high-tensile steel effectively and reducing the weight of steel materials. Become.
Lattice beams have lower rigidity than truss beams, so by setting the prestress added with tension cables and the material of the lattice beams appropriately, even if the beams have a large span, a composite of relatively small beams is used. It can be a lattice beam. Since a large number of lattice materials can be omitted from the lattice beam, the production cost associated with processing, welding, and the like of many lattice materials can be significantly reduced.
Lattice material is installed near the both ends of the lattice beam.
Since it is a digit, a relatively large song that occurs near both ends
Setting moment can be reduced.

According to the composite lattice beam of the second aspect, the first aspect is provided.
The same effect as described above is obtained , but the lattice beam is a plane lattice beam having one upper chord member and one lower chord member, and is suitable for a beam having a relatively small span, but is also applicable to a beam having a large span. According to the composite lattice beam of the third aspect, the same effect as the first aspect is obtained.
The lattice beam is a three-dimensional lattice beam having two upper chord members and two lower chord members, and is suitable for a beam having a relatively large span, but is also applicable to a beam having a small span. According to the composite lattice beam of claim 4 , in claim 2 or claim 3 , the main tension cable can suppress the downward bending deformation of the lattice beam, and the auxiliary tension cable can upwardly move the lattice beam by wind load or the like. It is possible to suppress the bending deformation of the.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an example of the case in which the present invention is applied to a composite lattice beam having a roof structure for a hangar such as an aircraft. And beam structures of various large span structures such as event facilities. As shown in FIG. 1, the hangar 1 is a large span structure having a width of about 100 m or more, and the hangar 1 is basically a roof structure 2
And a pair of left and right side wall structures 3 that support both left and right ends of the roof structure 2. The roof structure 2 is provided with, for example, four composite lattice beams 10 extending in the left-right direction, and each side wall structure 3 has a column member 4 included in the same plane as the composite lattice beam 10.
The left and right ends of each composite lattice beam 10 are connected to the upper end of the corresponding column member 4 and are supported by the column member 4.

The composite lattice beam 10 will be described. As shown in FIG. 2, the composite grid beam 10 basically includes a gentle-graded mountain-shaped grid beam 20 and a plurality of continuous tension cables 40 that prestress the grid beam 20. . The lattice beam 20 includes an upper chord member 21 and a lower chord member 2
2 and a plurality of bundles 23 connecting the upper chord 21 and the lower chord 22 with a plurality of bundles 23 arranged at predetermined intervals in the span direction. However, in this lattice beam 20, there are a plurality of pressure plates 24 welded to the upper chord member 21 and the lower chord member 22 at an intermediate position between the bundle members 23 and 23, and the tension cable 40 is projected downward. A plurality of pressure plates 24 having a function of regulating the position in a parabola curve are provided, and reinforcing lattice members 25 are also provided at portions near both ends of the lattice beam 20, but the lattice member 25 is necessary. It is provided in accordance with it and can be omitted.

The lattice beams 20 are each composed of a single upper chord material 21.
And the lower chord member 22, the upper chord member 21 and the two lower chord members 22.
And a three-dimensional lattice beam having one lower chord member 22 or a three-dimensional lattice beam having two upper chord members 21 and two lower chord members 22, respectively. Also, the grid beam 2
0 is not limited to a chevron lattice beam, and various lattice beams such as a parallel chord lattice beam and a parallel chord lattice beam with a gradient (see FIG. 6) can be applied.

As the steel material for the upper chord material 21, lower chord material 22 and bundle material 23, various materials such as pipe material, rectangular pipe material, H-shaped steel material, angle material, channel material and the like can be applied.
The tension cable 40 has a structure in which a large-diameter wire obtained by combining a large number of thin steel wires is covered with a synthetic resin coating material as required, and each end portion of the tension cable 40 is an end portion of the lattice beam 20. Alternatively, the tension cable 40 is connected to the vicinity of the end via a fixing plate member so that the tension of the tension cable 40 does not act on the column member 4, that is, the tension cable 40 is balanced inside the lattice beam 20. is disposed convex para Bo La curved downward as the lowest in midspan portion of the lattice girder 20, tensioning cable 40 movement limit in the vertical direction Bearing plate 23 in the span direction predetermined intervals The tension cable 40 is appropriately set according to the own weight of the lattice beam 20, the own weight of the portion of the roof structure 2 shared by the lattice beam 20, the external load due to snow, the span of the lattice beam 20, and the like. Tension (eg If, several hundred tons) is given,
The tension cable 40 is configured to apply a prestress to the lattice beam 20 for suppressing the downward deformation of the lattice beam 20. It is desirable to provide a plurality of tension cables 40, but it is also possible to provide one tension cable 40.

A tension cable 40 provided on the lattice beam 20.
The extension mode of No. will be described. As shown in FIG. 2, it may be a plurality of tension cables 40 of the convex downwardly para Bo <br/> La curved continuous over the entire span of the lattice girder 20 is provided,
As shown in FIG. 3, a plurality of first tension cables 41 that apply a prestress that suppresses downward flexural deformation to about half the span on the center side of the lattice beam 20, and the lattice beam 2.
A pair of left and right second tension cables 42 for applying a pre-stress that suppresses downward bending deformation may be provided on each end side portion of about 0/4 span.

In the case where an upward wind load acts on the roof structure 2, as shown in FIG.
In, provided with a convex para ball <br/> La curved plurality of main tensioning cable 40 downwardly continuous over its entire span, upwardly successive over the entire span convex para a plurality of sub-tension cable 43 of Bo La curved provided to set the tension of the auxiliary tensioning cable 43, for example in the order of about 0-20% of the tension of the main tension cable 40. As described above, when the sub-tension cable 43 is provided, when an upward wind load acts on the lattice beam 20, the sub-tension cable 43 causes the lattice beam 20 to move.
Upward bending deformation is suppressed. When the sub-tension cable 43 is provided, the tension of the main tension cable 40 needs to be set to be large by the tension of the sub-tension cable 43. The tension cable 43 functions effectively.

As shown in FIG. 5, a plurality of first main tension cables 4 for applying a pre-stress for suppressing a downward bending deformation to about a half of the span at the center of the span of the lattice beam 20.
1 and a pair of left and right second main tension cables 42 that apply a prestress that suppresses downward bending deformation to each end side portion of the lattice beam 20 and a lattice. A plurality of first auxiliary tensioning cables 44 for applying a prestress that suppresses upward deformation to approximately half of the span at the center of the span of the beam 20, and approximately one-fourth of each end side portion of the lattice beam 20 A pair of left and right second auxiliary tension cables 45 that apply prestress that suppresses upward bending deformation may be provided in the portion.

As shown in FIG. 6, in a composite lattice beam 10A comprising a parallel string lattice beam 20A with a gradient and tension cables 46a and 46b, a tension cable 46a extending from the top to one end of the lattice beam 20A is provided. A tension cable 46b extending from the top to the other end of the lattice beam 20A may be provided. The ends of the tension cables 46a and 46b are supported by being connected to the fixing plate member 26. However, as shown in FIG. 7, a tension cable 46 in which the end of the tension cable 46a and the end of the tension cable 46b are continuous may be provided.
Reference numeral 27 denotes a fixing plate member.

Next, a description will be given of a plurality of examples of the tension cable extension form and the supporting plate. 8, FIG. 10, FIG. 12, and FIG. 14, which are plan views of the composite lattice beam, the lattice beam is shown in a state in which the span is reduced as compared with the width in the direction orthogonal to the span. As shown in FIGS. 8 and 9,
In the case of the three-dimensional composite lattice beam 10B provided with two upper chord members 21 and two lower chord members 22, a plurality of tension cables 40 are arranged in parallel in a straight line in plan view, and both ends of the plurality of tension cables 40. The parts are fixed to the fixing plate member 28, respectively.
The shapes of the pressure bearing plates 24a, 24b, 24c and the structure for supporting the tension cable 40 in this case are shown in FIGS.
As shown in FIG.

As shown in FIGS. 10 and 11, a three-dimensional composite lattice beam 1 having one upper chord member 21 and two lower chord members 22 is provided.
In the case of 0C, the plurality of tension cables 40 are arranged such that the distance between the tension cables 40 increases toward the center of the span in plan view,
Both ends of these tension cables 40 are fixed to the fixing plate member 28, respectively. Bearing plates 24d, 2 in this case
The shapes of 4e and 24f and the structure for supporting the tension cable 40 are as shown in FIGS.

As shown in FIGS. 12 and 13, a three-dimensional composite lattice beam 1 having two upper chord members 21 and one lower chord member 22 is provided.
In the case of 0D, the plurality of tension cables 40 are arranged such that the distance between them becomes smaller toward the center of the span in a plan view, and both ends of these tension cables 40 are fixed to the fixing plate member 28, respectively. ing. Bearing plate 24 in this case
The shapes of g, 24h and 24i and the structure for supporting the tension cable 40 are as shown in FIGS. 13 (a) to 13 (c).

As shown in FIGS. 14 and 15, a plane composite lattice beam 1 having one upper chord member 21 and one lower chord member 22 is provided.
In the case of 0E, the plurality of tension cables 40 are arranged in parallel on both sides of the lattice beam in a plan view, and the two tension cables 40
Both end portions of are fixed to the fixing plate member 28, respectively. In this case, the shapes of the support plates 24j, 24k, and 24m and the structure for supporting the tension cable 40 are as shown in FIGS. As shown in the above multiple examples, the upper chord material 2
In order to restrict the position of the tension cable 40 in the vertical direction via the supporting plates 24a to 24m joined to the first and lower chord members 22, the component force of the tension of the tension cable 40 is reliably applied to the upper chord member 21 and the lower chord member 22. Can be communicated to.

The operation of the composite lattice beam 10 described above will be described. A tension cable 40 for applying a prestress is provided on the lattice beam 20 mainly composed of the upper chord member 21, the lower chord member 22, and a plurality of bundle members 23 connecting the upper chord member 21 and the lower chord member 22. Therefore, a rational composite lattice beam can be obtained in which the weakness of the lattice beam, in which the amount of deflection is increased, is compensated for by the tension cable 40 and the advantages of the lattice beam 20 are utilized. That is, since the rigidity ratio of the lattice beam (the ratio of the bending stiffness of the lattice beam 20 to the extension stiffness of the tension cable 40) is small, the prestress introduction efficiency is high, and the tension force is much smaller than that of the composite truss beam. The bending deformation of the lattice beam 20 can be effectively suppressed. In other words, since the bending amount of the lattice beam 20 is large, the tension cable 40 achieves the prestress introduction function and the suspension function of suspending and supporting the lattice beam 20. In the composite truss beam, the ratio of the tension cable exerting the suspension function is very small.

By applying pre-stress with the tension cable 40, the deformation of the lattice beam 20 can be suppressed, so that a stress-based design can be performed instead of a rigid-based design. Therefore, high-tensile steel is applied. As a result, the weight of the steel material can be reduced. Further, since the lattice beam 20 is lighter than the truss beam, by appropriately setting the prestress applied by the tension cable 40 and the material of the lattice beam 20, even a beam with a large span is relatively small. It can be a composite lattice beam with a beam back. Particularly, in the composite lattice beam 10,
Since a large number of lattice materials can be omitted, the production cost associated with processing, welding, and the like of a large number of lattice materials can be significantly reduced.

When the lattice members 25 are provided in the vicinity of both ends of the lattice beam 20, the rigidity of the parts near both ends where a relatively large bending moment is generated can be increased. In addition, since the tension cable 40 is configured to apply a prestress for displacing the lattice beam 20 upward, it is possible to suppress the lattice beam 20 from bending downward due to its own weight or the like. As shown in FIGS. 4 and 5, main tension cables 40 to 42 for applying a prestress for displacing the grid beam 20 upward, and the prestress is sufficiently small compared to the prestress, and the grid beam 20 is moved downward. When the auxiliary tension cables 43 to 45 for applying the pre-stress for displacing the lattice beams 20 are provided, the main tension cables 40 to 42 can suppress the lattice beam 20 from being bent downward and deformed.
Lattice beam 20 due to wind load or the like by sub-tension cables 43 to 45
Can be suppressed from bending and deforming upward.

Hereinafter, regarding the composite truss beam in which the tension cable is provided in the truss beam, the simple lattice beam without the tension cable, and the complex lattice beam in which the tension cable is provided in the lattice beam, the weight of steel material and the required tension force of the tension cable ( In order to quantitatively compare and examine the required tension, etc.
The analysis result of the structural analysis of the beam will be described. The prerequisites for this structural analysis are as follows. 1) Actual span of beam x Beam back ... 120m x 6m 2) Uniformly distributed load acting on beam ... 2.5t / m 3) Limit value of deflection amount ... 25cm 4) Introduction Tension (introduced tension) ······ Introduced until the amount of deflection reaches the limit value 5) Buckling length of upper chord material and lower chord material ··· 10 m 6) Thickness according to width / thickness ratio of upper chord material and lower chord material Restrictions (H-50
0x500) is as shown in Table 1, and the member symbol is shown in FIG.
And H indicates an H-section steel.

[0029]

[Table 1] The results of the structural analysis are as shown in Tables 2 and 3, and FIGS.

As can be seen from Tables 2 and 3, in the composite truss beam, the introduction efficiency of the tension force is 0.023 cm / t, the total weight is 63 t, the introduction tension force is 463 t, and the total tension acting on the tension cable is 520 t. On the other hand, in the composite lattice beam, the tension introduction efficiency is 0.382 cm / t, the total weight is 60 t, the introduction tension is 238 t, and the total tension acting on the tension cable is 724 t. Therefore, compared with the composite truss beam, in the composite lattice beam, the introduction efficiency of the tension force is high, the total weight of the steel materials is small, and the introduction tension force is significantly reduced. However, in the composite lattice beam, the total tension of the tension cables increases due to the suspension action of suspending the lattice beams with the tension cables, so that the cable diameter itself increases. In Tables 2 and 3, the PC cable is a tension cable.

As a result of the analysis, the distributions of the displacement, axial force and moment of the composite truss beam are shown in FIGS. 17, 18 and 19, respectively.
The distribution of the displacement, axial force and moment of the simple lattice beam without the tension cable is shown in FIGS.
As shown in FIG. 22, the distribution, axial force, and moment distribution of the composite lattice beam are as shown in FIGS. 23, 24, and 25, respectively. The lattice beam may be partially or entirely made of a high-tensile steel material, and the tension cable does not necessarily need to be provided over the entire span of the lattice beam. A tension cable may be provided only in the 1/3 span portion. Further, the composite lattice beam of the present invention can be applied not only to large span beams but also to small and medium span beams, and can also be applied to road bridges and bridge beams in addition to the beams of various structures described above.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hangar according to an embodiment.

FIG. 2 is a configuration diagram of a composite lattice beam of the hangar of FIG. 1;

FIG. 3 is a diagram corresponding to FIG. 2 showing an example in which the form of the tension cable is changed.

FIG. 4 is a diagram corresponding to FIG. 2 in which an additional tension cable is added.

FIG. 5 is a diagram corresponding to FIG. 3 of an example in which an auxiliary tension cable is added.

FIG. 6 is a partial configuration diagram of another embodiment of the composite lattice beam.

7 is a partial configuration diagram of a composite lattice beam in which a part of the composite lattice beam of FIG. 6 is modified.

FIG. 8 is a plan view of an example of a composite lattice beam.

9 is a configuration diagram of a plurality of bearing plates and the like at different positions of the composite lattice beam of FIG.

FIG. 10 is a plan view of an example of a composite lattice beam.

11 is a configuration diagram of a plurality of support plates and the like at different positions of the composite lattice beam of FIG.

FIG. 12 is a plan view of an example of a composite lattice beam.

13 is a configuration diagram of a plurality of bearing plates and the like at different positions of the composite lattice beam of FIG.

FIG. 14 is a plan view of an example of a composite lattice beam.

15 is a configuration diagram of a plurality of bearing plates and the like at different positions of the composite lattice beam of FIG.

FIG. 16 is an explanatory diagram of member symbols of a composite truss beam and a composite lattice beam subjected to a structural analysis.

FIG. 17 is a displacement distribution diagram of a composite truss beam obtained by structural analysis.

FIG. 18 is an axial force distribution diagram of the composite truss beam obtained by structural analysis.

FIG. 19 is a moment distribution diagram of a composite truss beam obtained by structural analysis.

FIG. 20 is a displacement distribution diagram of a simple lattice beam obtained by structural analysis.

FIG. 21 is an axial force distribution diagram of a simple lattice beam obtained by structural analysis.

FIG. 22 is a moment distribution diagram of a simple lattice beam obtained by structural analysis.

FIG. 23 is a displacement distribution diagram of a composite lattice beam obtained by structural analysis.

FIG. 24 is an axial force distribution diagram of a composite lattice beam obtained by structural analysis.

FIG. 25 is a moment distribution diagram of a composite lattice beam obtained by structural analysis.

[Explanation of symbols]

10, 10A to 10E Composite lattice beam 21 Upper chord 22 Lower chord 23 Bundle 25 Lattice 40 Tension cable (main tension cable) 41, 42 Main tension cable 43, 44, 45 Secondary tension cable

[Table 2]

[Table 3]

Claims (4)

(57) [Claims] 1. A lattice beam mainly composed of one or a plurality of upper chords, one or a plurality of lower chords, and a plurality of bundles connecting the upper chords and the lower chord , wherein both ends thereof are provided. With
A lattice beam provided with a lattice member in the vicinity of the lattice beam, and a tension cable for applying prestress to the lattice beam to suppress downward bending deformation of the lattice beam. And composite lattice beams. 2. The composite lattice beam according to claim 1, wherein the lattice beam is a plane lattice beam having one upper chord member and one lower chord member. 3. The composite lattice beam according to claim 1, wherein the lattice beam is a three-dimensional lattice beam having two upper chord members and two lower chord members. 4. A sub-stress provided to the lattice beam so as to apply a pre-stress that is sufficiently smaller than the pre-stress of the tension cable and that suppresses upward bending deformation of the lattice beam. composite lattice girder according to claim 2 or claim 3, characterized in that a tension cable.