JPS63125758A - Truss structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention particularly relates to a truss structure constituting a long span structure.

``Prior Art'' Conventionally, in structures having a large span, a truss structure has been used, which is advantageous both structurally and economically, since it deforms less than the members subjected to the bending moment. However, even with these trusses that have been commonly used in the past, when the length (span) becomes extremely large (long span), not only does the deflection increase, but the overall weight of the structure increases. However, there is a problem that the weight of the truss increases, making it uneconomical.As a result of intensive research to solve this problem, the present applicant et al. I invented it and have already applied. Figure 5 shows an example.
The lower chord member 23 of the truss beam 21 assembled with the upper chord member 22, the lower chord member 23, and the lattice member 27 is composed of H-beam steel,
Ribs 25 are provided at predetermined intervals on both sides of the weave 24 of this H-beam steel, and a PC steel wire 26 is placed through the ribs 25 and extends over the entire length of the lower chord member 23, and by tensioning the wire, Prestress is introduced into the lower chord material 23.

"Problems to be Solved by the Invention" By the way, the truss to which prestress is introduced in this way is not only capable of reducing its deflection, but also reduces the tensile force applied to the lower chord member 23 due to the introduced prestress. This has the excellent effect of being able to bear part of the load and thereby reducing the weight of the truss, but since the cross section of the H-beam is determined by the fit of the prestressing steel 26, In addition to having to make the H-shaped steel unnecessarily large, in order to prevent deformation due to one-sided pulling,
Two pieces of PC steel are required for one lower chord piece, and the cost of the material itself and the tension required are time-consuming.
Furthermore, there were other points that should be improved, such as the need to use an expensive coated PC steel wire in consideration of the corrosion and rust prevention of the PC steel wire 26.

The present invention has been made in view of the above-mentioned circumstances, and is a truss structure that reduces deflection and realizes a truss with prestress introduced that also realizes weight reduction, and which is more economically advantageous. Its purpose is to provide the following.

"Means for Solving the Problems" A truss structure according to the present invention is a truss structure assembled in a truss shape by an upper chord member, a lower chord member, and a lattice member, in which at least one of the upper chord member and the lower chord member is It is characterized in that it is composed of a steel pipe, and a prestressed steel material is inserted into the steel pipe, and prestress is introduced by the tension of the prestressed steel material.

``Effect j The prestress introduced into the strings can reduce the stress generated in the strings, thereby suppressing the deflection of the truss structure and reducing its weight. By using a steel pipe as the chord material and positioning the prestressed steel material at the center of the string material, only one prestressing steel material can be used, which reduces the amount of prestressed steel material used and also simplifies tensioning work. Furthermore, since the steel pipe can serve as a form that protects the PC steel material, protective measures for the PC steel material are not required.

"Example" Hereinafter, an example of the present invention will be described with reference to the drawings. 1 to 4 show the present invention applied to a parallel chord truss beam, which is one of the truss structures. The truss beam according to the present invention is generally designated by the symbol l in FIG.

The truss beam 1 is assembled with an upper chord member 2, a lower chord member 3 made of a steel pipe and parallel to the upper chord member 2, and a lattice member 4 that connects the upper chord member 2 and the lower chord member 3. In this embodiment, the upper chord material 2 and the lattice material 4 are also
Like the lower chord member 3, it is made of steel pipe.

The connection between the lower chord member 3 made of a steel pipe and the lattice member 4 is achieved by providing a rib plate 6 horizontally protruding from the lower chord member 3 and connecting the lattice member 4 to the lower chord member 3, as shown in FIG. A connecting plate 7 is provided at the lower end of the connecting plate 7 so as to protrude therefrom, and this connecting plate 7 is joined to the rib plate 6 across the radius of the lower chord member 3.

Note that bearing pressure plates 8 are provided at the ends of the rib plates 6, respectively.

A PC steel material 5 is inserted through the entire length of the lower chord member 3 made of a steel pipe. PC steel material 5
As shown in FIG. 2, the end portion thereof is tightened by a nut 10 provided through the fixing plate 9a, so that it is fixed to the fixing plate 9a in a tensioned state. The PC steel material 5 may be either a PC steel bar or a PC steel wire, but even if a PC steel wire is used, only the fixing portion is made of a steel bar by using a crimp grip or the like. This allows tensioning by tightening the nut IO. In addition, the lower chord material 3 near the fixing part
As shown in FIG. 2 and the like, a trumpet-shaped guide pipe 11 is provided inside thereof with its tapered end facing toward the fixing section. This is so that when inserting the PC steel material 5 into the lower chord member 3, the tip thereof can smoothly pass through the fixing plate 9a, etc., and also to hold the PC steel material 5 at the centroid of the chord member. belongs to.

In the truss beam I configured in this way, prestress is introduced into the lower chord 3 by the prestressed PC steel material 5 which is inserted into the lower chord 3 and is tensioned, thereby reducing the load received by the lower chord 3, especially the tensile force. As a result, the deflection of the truss beam 1 can be suppressed, and the weight of the truss l can also be reduced. Moreover,
By using a steel pipe for the lower chord material 3, PCtf4 material 5
can be located at the center of the lower chord, so there is no unbalanced introduction force unlike when using H-shaped steel, so only one PC steel can be used.

This not only makes it possible to reduce the amount of PC steel material 5 used, but also requires only one tensioning operation, resulting in cost reductions in terms of both materials and operations. Furthermore, since the PC steel material 5 is inserted into the steel pipe and is not exposed to the outside, there is no need to use an expensive coated PC steel wire for corrosion and rust prevention.

FIG. 3 shows the PC steel material 5 fixed in the middle of the truss beam l, and is an enlarged view of the lower end joint 12a of the lattice material 4 in FIG. 1(a). . The tension of the PC steel material 5 is fixed to the fixing plate 9b, which also serves as the bearing pressure plate 8, by tightening the nut 0, similar to the fixation at the end of the lower chord member described above. Here, the lower chord member 3, that is, the nut 10 extending to the left side of the fixing plate 9b in the figure
The lower chord member 3 to which prestress has been introduced by the fastening of the lower chord member 3 and the lower chord member 3 extending to the right side of the fixing plate 9b are not the same, and the lower chord member 3 extending to the right side has a T They are connected via a shaped steel 13a. Reference numeral I4 is a reinforcing rib for the T-shaped steel 13a.

By doing this, a space is created between the T-beams 13a, which allows the nut IO to be tightened.

Since the stress generated in a member differs depending on the part of the lower chord member, it is necessary to provide a fixing part in the middle of one span as described above so that tension can be introduced separately into any section. This makes it possible to introduce prestress corresponding to the stress generated in each part.

Furthermore, when connecting the lower chord members 3 to each other, as shown in FIG. The T-beams 13b are attached by welding or the like, and the ends of these T-beams 13b are connected.

When inserting the prestressed steel material 5, the prestressed steel material 5 is guided by the tapered end shape of the lower chord material 3 and can pass smoothly through this connection, and the connection of the T-shaped steel 13b is
This can be accomplished by any conventional means generally used for connecting steel materials, such as bolting using splice plates 15.

Further, it is also possible to provide a guide sleeve 16 at the tip of the T-shaped steel 13b, and in this case, the guidance of the PC steel material 5 is performed more reliably, and the insertion work becomes smoother.

In addition, in this example, the present invention is applied to the - of the truss structure.
Although the truss beam has been described as an example, the truss structure of the present invention is not limited to this, and may be a triangular truss or a three-dimensional truss, for example. Furthermore, depending on the state of stress that occurs, prestress may be introduced into the upper chord member 2 in response to this.

"Effects of the Invention" As explained above, according to the present invention, in a truss structure constructed of an upper chord member, a lower chord member, and a lattice member assembled in a truss shape, at least one of the upper chord member and the lower chord member is made of a steel pipe. At the same time, a PC steel material is inserted into the steel pipe, and the PC
Since prestress is introduced by tensioning the steel material, it is possible to reduce the stress generated in the chord members as much as possible, thereby suppressing the deflection of the truss structure and reducing the weight of the truss structure. be able to. Moreover, these can be made by using steel pipe as the string material into which prestress is introduced.
By positioning the C steel material at the center of the chord material, only one PC steel material is used, which reduces the amount of PC steel material used and at the same time simplifies tensioning work.Furthermore, the steel pipe protects the PC steel material. Since it can be formed into various shapes, it has excellent effects such as eliminating the need for protection measures for PC steel materials such as antiseptic and rust prevention, and can be realized at low cost.

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention, FIG. 1(a') is a partial front view of the truss beam l, and FIG. 1(b) is a partial front view of the truss beam l.
is an I-1' sectional view in Figure 1(a), Figure 2 is a partial front view showing the lower end joint of the lattice and the anchoring end of the PC steel material, and Figure 3 is a partial front view showing the anchoring part in the middle of the span of the truss beam 1. Front view, FIG. 4 is a front view showing the connection means of the lower chord member 3. Fig. 5 shows a conventional example, Fig. 5 (a) is a partial front view of a truss beam, and Fig. 5 (b) is an n in Fig. 5 (a).
-n' sectional view. ■・・・Truss beam, 2・・・Top chord member,
3... Lower chord material, 4... Lattice material,
5...PC steel material.

Claims (1)

[Claims] In a truss structure assembled in a truss shape by an upper chord member, a lower chord member, and a lattice member, at least one of the upper chord member and the lower chord member is composed of a steel pipe, and a PC steel member is inserted into the steel pipe, and the PC steel member A truss structure characterized in that prestress is introduced by the tension of the truss structure.