JPH0568581B2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a method of constructing a truss structure,
The present invention mainly relates to a method for constructing a truss structure suitable for use in constructing extremely large span structures (approximately 50 m or more).

"Prior Art" In general, a so-called truss structure, in which a triangular shape is formed by upper chord members, lower chord members, and lattice members, is known as a structure for building lightweight and strong architectural and civil engineering structures. however,
In the case of such a truss structure, when the architectural/civil engineering structure becomes large-scale, especially when the span becomes extremely long, such as 100 m or more,
There were problems in that not only did the columns and beams that make up the structure undergo large deflections, but the weight of the truss structure increased as a proportion of the overall weight of the structure, making it uneconomical. Therefore, in view of the above-mentioned problems, the present applicant et al. tensioned the prestressing steel members that are integrally arranged along at least one of the chord members and lattice members of the truss structure. We have proposed a truss structure in which prestress is introduced into the truss structure to counteract the stress state occurring in the structure (Japanese Patent Application No. 61-21501).
issue). According to this truss structure, the stress of the member in which the prestressing steel material is arranged is reduced by introducing prestress, and the deflection of the structure is reduced, and the weight of the member is reduced by reducing the cross section of the member at the design stage. reduction is possible.

"Problems to be Solved by the Invention" By the way, the truss structure proposed by the applicant et al. has a prestressing steel material integrated with the chord or lattice material of a conventional truss structure, and the structure is However, in this truss structure, a means of introducing prestress such as prestressing steel is permanently required for each structure.
There was a possibility that this could be a factor in increasing costs.

This invention was made in view of the above circumstances,
The purpose of this study is to provide a method for constructing truss structures that can realize ultra-large span structures without permanently using prestress introducing means such as prestressing steel.

``Means for Solving the Problems'' Therefore, the present invention aims to provide a beam member of a truss structure assembled in a truss shape using an upper chord member, a lower chord member, and a lattice member, between a pair of column members erected facing each other. When constructing a truss structure by erection, the beam member is made into a trapezoidal truss structure by forming both left and right ends of the lower chord member shorter than the upper chord member, and the upper chord member of such a beam member is made into a trapezoidal truss structure. After this beam member is erected between the column members by pin-joining the top end of the column member and the upper end of the column member, a compressive force is applied to the lower chord member of the beam member to introduce prestress into the beam member and the lower chord The material is shrunk, and then the lower chord of the beam member and the tip of the connecting member protruding from the column member so as to form both left and right ends of the lower chord when the beam member is erected on the column member. The above problem is solved by configuring a method for constructing a truss structure in which the prestress is released after the parts are connected.

"Operation" In this invention, prestress in the compression direction is introduced into the lower chord of the beam member, and then the prestress is released after connecting both ends of the lower chord to the column member via the connecting member. As the prestress is released, the lower chord material that has shrunk due to the prestress attempts to return to its original state, and a horizontally outward stretching force is applied to the column member. As a result, the column member applies a force that counteracts the stretching force to the lower chord member as a reaction force, and the beam member is lifted upward by the action of the reaction force, causing a bulge in the beam member.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 4 are diagrams showing a steel truss structure constructed by a method for constructing a truss structure according to an embodiment of the present invention. In these figures, what is denoted by reference numerals 1 and 1 are columns (column members) made of steel frames, and these pair of columns 1 and 1 are erected on the ground G in a state where they face each other. Pillar 1,
At the upper end of 1 is a steel truss structure beam (beam member) 2
has been erected.

As shown in FIGS. 2 to 4, this beam 2 includes an upper chord member 3 made of a steel pipe, a lower chord member 4 made of H-beam steel, and a lattice member 5 that connects these upper chord members 3 and lower chord members 4. It is assembled into a truss structure. Ribs 6, 6, . A sheath tube 7 in the form of a hollow tube is provided. A PC steel wire 8 is inserted into the sheath pipe 7 during construction of a truss structure, which will be described later. Moreover, the beam 2 is
As shown in FIG. 2, both left and right ends of the lower chord member 4 are formed to be shorter than the upper chord member 3, that is, it has a trapezoidal truss structure with a short turn.

The beam 2 having such a configuration is constructed between the columns 1, 1 by pin-joining both ends of the upper chord member 3 to the upper ends of the columns 1, 1, respectively. Further, on the pillar 1, a connecting member 9 in an H shape with a length corresponding to the shortened portion of the lower chord 4 of the beam 2 is installed so that it is in line with the lower chord 4 when the beam 2 is erected. It is rigidly protruded at a certain position by means such as welding. The tips of these connecting members 9, 9 are welded and connected to both left and right ends of the lower chord member 4.

Next, a method for constructing a truss structure, which is an embodiment of the present invention, will be described with reference to FIGS. 5 and 6.

First, pillars 1 and 1 are installed on the ground G with an interval corresponding to the span interval of the beams 2. and,
Each opposing surface of these pair of pillars 1, 1 will have a beam 2 later.
Connecting members 9, 9 are provided in a protruding manner by welding or the like, respectively, at positions that will be in line with the lower chord member 4 when the lower chord member 4 is erected. Or instead of welding,
Means such as bolt tightening may also be used. Next, the beam 2 assembled in advance into a trapezoidal truss structure as shown in FIG. By doing so, this beam 2 is constructed between the columns 1 and 1 (Fig. 5). At this time, at the same time as the beam 2 is assembled, a
The PC steel wire 8 is inserted over its entire length.
Alternatively, if the columns 1, 1 have a structure that has a certain width in the column direction (the direction perpendicular to the page in FIG. 5), one end of the columns 1, 1 in the direction perpendicular to the column direction ( That is, a temporary gantry extending in the direction in which the beam 2 extends is provided, and after assembling the beam 2 on this temporary gantry, the beam 2 is slid in the column direction to a predetermined position,
Thereafter, both ends of the upper chord member 3 of the beam 2 and the upper ends of the columns 1, 1 may be joined with pins, respectively.

In this state, a movable scaffold (not shown) with a height reaching both ends of the lower chord member 4 of the beam 2 is placed on the side of the columns 1, 1, and a well-known firming force introduction means such as a jack is used to
After stretching the PC steel wire 8 from both ends, the both ends are fixed to both ends of the lower chord member 4.
By applying a compressive force (arrows P, P in FIG. 5) to the lower chord member 4, prestress is introduced into the lower chord member 4. Accordingly, as the prestress is introduced, the beam 2 is brought into a state in which it is contracted in its longitudinal direction from the shape shown by the imaginary line in FIG. 5 to the shape shown by the solid line.

Next, with prestress introduced to the lower chord member 4, the tips of the connecting members 9, 9 are connected to the lower chord member 4.
Connect by welding to both left and right ends (Figure 6). Alternatively, the connection may be made by tightening high-tensile bolts or the like, but the connection means must be strong enough to withstand the stretching force of the lower chord member 4, which will be described later. Furthermore, when the fixation of the PC steel wire 8 to the lower chord member 4 is released and the prestress on the lower chord member 4 is released by pulling out the PC steel wire 8 from the sheath pipe 7, the lower chord member 4 returns to its original state. In an attempt to return to the shape (see imaginary line in Figure 5), a horizontally outward stretching force (arrows P', P' in Figure 6) is applied to the columns 1,1. The pillars 1, 1 apply a force counteracting the extension force to the lower chord member 4 as a reaction force, and the upper part of the beam 2 is lifted by the reaction force acting on the lower chord member 4, as shown by the solid line in Fig. 6. As shown in the figure, a swelling occurs.

In other words, in such a steel truss structure, when beam 2 is built into columns 1 and 1, a uniform overload acts on the top surface of beam 2, resulting in a moment distribution as shown by the dotted line in Figure 7. . However, at the stage when the prestress introduced to the lower chord member 4 of the beam 2 is released, a horizontal extension force acts on the columns 1, 1, and the columns 1, 1 counteract the extension force as a reaction force. Apply the force to the lower chord member 4. Therefore, the moment distribution in this state is as shown by the solid line in FIG. Therefore, prestress in the compression direction is introduced into the apparent beam 2 and the lower chord member 4,
As a force that cancels out the overload load acts on most of the beam 2, the stress generated in the lower chord member 4 is reduced and the deflection of the beam 2 is reduced, and the weight of the lower chord member 4 can be reduced at the design stage. It becomes possible.

In other words, according to the construction method of the truss structure of this embodiment, prestress is introduced by the PC steel wire 8 only when connecting the lower chord member 4 of the beam 2 to the columns 1, 1 via the connecting members 9, 9. If this is done, the apparent prestress will act on the lower chord 4 even if the PC steel wire 8 is pulled out after connecting the lower chord 4 to the columns 1, 1, so the PC steel wire 8 will not need to be used permanently. Not only can the deflection of the beam 2 be reduced, but also the weight of the lower chord member 4 can be reduced, making it possible to realize a structure with an extremely large span (approximately 50 m or more). By the way, PC
The steel wire 8 can be repurposed, and an extremely large span structure can be constructed economically and efficiently.

Note that the method for constructing a truss structure of this invention is as follows:
The details and the shape of the truss structure to be constructed are not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. As an example, the above embodiment was a so-called one-layer rigid-frame truss structure, but this could be connected in the height direction to form a multi-layer rigid-frame structure, or connected in the length direction to form a multi-span truss structure. Of course, a rigid frame structure may also be used. Further, the method of introducing prestress is not limited to the method using the PC steel wire 8 as in the above embodiment, but may also be introduced using a PC steel bar or a PC steel stranded wire. Also, PC steel wire 8
Regardless of the method described above, it is also possible to introduce prestress by interposing an elongating means such as a jack between the column 1 and the lower chord member 4 of the beam and widening the elongating means. Furthermore, the shape and assembly method of the truss may be any known shape and assembly method, and it goes without saying that the material of each chord member and lattice member is not limited to steel, but may also be wood or the like.

Here, in the truss structure of the above embodiment, as shown in FIG. 7, moments are concentrated at the upper ends of the columns 1 and 1 and at both ends of the upper chord member 3 of the beam 2, and a relatively large stress is applied to the members in these parts. There is a risk that the product may be bent or bent. Therefore, if members to which prestress in the compressive direction has been introduced are attached in advance to both ends of the above-mentioned column upper ends 1, 1 and upper chord member 3, moment concentration on each member can be avoided.

"Effects of the Invention" As explained in detail above, according to the present invention, if prestress is introduced into the lower chord of a beam when it is connected to a column via a connecting member, the lower chord of the beam can be After connecting to the column, even if the prestress is released, the apparent prestress acts on the lower chord, so it is possible to reduce the deflection of the beam without permanently using prestress introducing means such as PC steel wire, and The weight of the lower chord members can be reduced, which makes it possible to realize super-large span structures.
Therefore, it becomes possible to reuse prestress introducing means such as PC steel wire, and it is possible to realize economical and efficient construction of super-large span structures.

[Brief explanation of drawings]

FIG. 1 is a front view showing a steel truss structure constructed by a truss structure construction method that is an embodiment of the present invention, and FIG. 2 is a front view showing only the beams of the truss structure. Figure 3 is an enlarged front view of the same beam, and Figure 4 is -' of Figure 3.
5 and 6 are diagrams for explaining a method for constructing a truss structure according to an embodiment of the present invention, and FIG. 7 is a truss structure constructed by the same method. FIG. 3 is a diagram showing the moment distribution acting on the 1... Column (column member), 2... Beam (beam member), 3...
...Top chord material, 4...Lower chord material, 5...Lattice material, 8...
...PC steel wire, 9...Connection member.

Claims (1)

[Claims] 1. A method of constructing a truss structure by constructing beam members of a truss structure assembled into a truss shape using upper chord members, lower chord members, and lattice members between a pair of column members that are erected facing each other. , the beam member is formed into a trapezoidal truss structure by forming both left and right ends of the lower chord member shorter than the upper chord member, and the upper chord member of the beam member and the upper end portion of the column member are joined with pins. After this beam member is installed between the column members, prestress is introduced into the beam member by applying a compressive force to the lower chord member of the beam member, and further, the lower chord member of the beam member and the beam member The truss structure is characterized in that the prestress is released after connecting the tip of the connecting member protruding from the column member so as to form both left and right ends of the lower chord member when the truss structure is erected. How things are built.