JPH0453226B2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention constructs a truss structure, especially a long span structure, in which the lower chord is made of a prestressed steel material and prestress is introduced by the prestressed steel material. This relates to truss structures.

``Prior Art'' Traditionally, parallel chord trusses, three-dimensional truss, etc. have been provided as truss structures.These truss structures can make the structure strong and can easily accommodate extensions. has advantages,
Widely used.

"Problems to be Solved by the Invention" However, in the conventionally commonly used truss, when the structure that it constitutes becomes long and large, the truss deflects greatly. Then, there was a problem that the ratio of the truss's own weight to the total weight of the structure became large, making it uneconomical.

The present invention was made in view of the above circumstances, and
The object of the present invention is to provide a truss structure that can reduce deflection and can be constructed economically.

"Means for Solving the Problems" Therefore, in order to achieve the above object, the present invention has the following features:
In a truss structure constructed of a top chord, a bottom chord, and a lattice material assembled into a truss shape, the bottom chord itself is made of prestressed steel material, and the prestressed steel material constituting the bottom chord is in a state of tension when it is connected to the lattice material. It was fixed to the lower end joint of the.

``Operation'' The PC steel material is fixed to the lattice joint at the bottom end of the truss under tension and generates tensile stress.
Prestress is introduced between the lattice material joints,
This makes it possible to suppress elongation between these lattice material joints.

"Example" Hereinafter, the first embodiment of the present invention will be described in Figures 1 to 5.
This will be explained with reference to the figures.

1 to 5 show the present invention applied to an inverted triangular truss beam, which is one of the truss structures.

In the figure, numeral 1 indicates an inverted triangular truss beam (hereinafter referred to as
(abbreviated as triangular truss beam). A triangular truss beam 1 is connected in parallel with a connecting member 2.
The upper chord member 3 of the book, the lower chord member 4 installed at a position forming an inverted isosceles triangle having the upper chord member 3 as the apex of the base angle, the two upper chord members 3 and the lower chord member 4. and a lattice material 5 that connects the two. The upper chord member 3, the joining member 2, and the lattice member 5 are made of steel pipes. The lattice material 5 also has an angle in the longitudinal direction of the triangular truss beam 1, and as shown in FIG.
A triangle is formed between the two.

The lower end of the lattice material 5, that is, the lattice material 5,
The ends that are not joined to the upper chord member 3 are joined to each other at the vertices of a triangle. These joints are equipped with a PC, which will be described later.
Fixing parts 6 for fixing the steel rods are provided respectively.

As shown in FIG. 3, the fixed part 6 has a cylindrical shape with an axis in the longitudinal direction of the triangular truss beam 1, and pressure receiving plates 7 are provided at both ends of the cylinder to close the openings. It is being A through hole 8 is bored in the pressure receiving plate 7, and a plurality of (four in the embodiment) PC steel rods 9 pass through the through hole 8. The PC steel bar 9 spans the entire length of the triangular truss beam 1, and a screw thread is provided at a portion of the PC steel bar 9 that corresponds to the fixing portion 6. A nut 10 that is screwed into the thread is provided on the outside of the pressure receiving plate 7. and,
The PC steel bar 9 has one end fixed to one end side of the last beam 1, and then the other end is fixed to the fixing part 6 in a tensioned state using a tension jack or the like (not shown). In other words, the PC steel bar 9 is fixed in a state where tensile stress is generated. That is, prestress is introduced by the PC steel rod 9 to the lower end of the lattice material joint. The PC steel bar 9 is fixed to the fixing portion 6 by screwing the nut 10 provided on the PC steel bar 9 into pressure contact with the pressure receiving plate 7. this is,
A fixing part is provided for each joint, and by fixing each fixing part 6 and the PC steel bar 9 in this way, prestress is introduced in accordance with the stress generated between the lower end joints of each lattice. This makes it possible to demonstrate rationality that leads to the most effective efficiency of force. Note that the means employed for this fixing is not limited to screw fixing, but any means that can be effectively adopted as a fixing means may be used. In addition, in this embodiment, there are multiple PC steel bars 9, which means that even if one of the PC steel bars 9 breaks, the load can be supported by other PC steel bars. In some cases, a plurality of design sheets are required in order to achieve this, and in cases where one design is sufficient, a plurality of design sheets is of course not required. Also, this
In this embodiment, the PC steel rod 9 is arranged in the third position.
As shown in the diagram, in a cross section perpendicular to the longitudinal direction, the lines connecting the four PC steel bars 9 form a square, and the diagonal lines that intersect perpendicularly to each other are oriented vertically and horizontally. , this can be made into an inverted T-shape, or by increasing the number of I
Of course, it is also possible to arrange the PC steel bar 9 so that its cross-sectional rigidity is increased so as to resist compression buckling even slightly, such as by using a mold. Furthermore, in the embodiment, each of the truss beams 1 over the entire length
Although the PC steel bar 9 is made into one piece, it can also be configured to connect a plurality of pieces using, for example, a coupling.
Moreover, in the plurality of PC steel bars 9 installed in parallel, for example, when reinforcing a beam or column in a reinforced concrete structure, the main reinforcement extending parallel to the longitudinal direction of the beam or column is approximately equal. These PC steel bars 9 are connected to each other as if adding stirrups at intervals.
As shown in the figure, they may be bound using a binding material 11. In this way, the PC steel rod 9 as the lower chord material can be made stronger.

Further, when a similar triangular truss beam 1a is orthogonal to the triangular truss beam 1, as shown in FIG. This can be achieved by creating a structure in which the holder is joined to the lower part of the holder.

Next, the operation of the triangular truss beam 1 configured in this way will be explained.

By the way, as can be said of all beams, a compressive force is applied to the top chord of the truss, and a strong tensile force is applied to the bottom chord. For this reason, the bottom chord stretches and the beam bends downwards, but this stretching of the bottom chord means that the lower joint of the chillas material that connects the bottom chord with the top chord This means that the space between departments will expand. In other words, if it were assumed that there were no lower chord members, the lower joints of the lattice members would be infinitely wide. The present invention is based on the idea that by suppressing the elongation between the lattice material joints, the deflection of the beam can also be reduced. Specifically, compressive force is exerted between the lattice joints by the PC steel rod 9 as a reaction force against the tensile force that causes elongation between the joints of the lattice material 5. Since the tensile force is canceled out by this compressive force, the bending deformation of the truss beam 1 becomes extremely small.

Furthermore, as shown in this example, the truss structure according to the present invention is a triangular truss.
In addition to not causing horizontal buckling (buckling) that may occur when tensioning the PC steel bar 9, when compared with a parallel chord truss, Furthermore, since the triangular truss is made by combining the two lower chord members of the parallel chord truss into one, it is extremely effective in streamlining processes such as tensioning and fixing the PC steel rods 9.

In addition, in this embodiment, the truss material, that is, the upper limit member 3, the joining member 2, which constitutes the triangular truss beam 1,
Although the lattice material 5 is made of a steel pipe, it is not limited to these steel pipes, and may also be a shaped steel such as an H-shaped steel.

Here, the method for constructing a truss structure composed of the above triangular truss beams 1 will be briefly explained using a roof as an example. First, the above triangular truss beams 1 are assembled into the ground, and Place it on top. The gantry is provided adjacent to the structure on which the roof, which is a truss structure, is to be erected. In addition, when the ground-assembled triangular truss beam 1 is placed on this gantry, the gap between the lower end joints of the lattice members 5 that are not yet restrained by the unstringing members 4, that is, the interval between the fixed parts 6, opens due to its own weight. To avoid this,
These fixed portions 6 are temporarily fixed using a connecting material or the like.
Once the triangular truss beam 1 is placed on the gantry, the triangular truss beam 1 is then set at a level that corresponds to the deflection when prestressing is introduced. At this point, the triangular truss 1 is supported by a stand or the like, and prestress by the lower chord member 4, that is, the PC steel bar 9, has not yet been introduced. After installing roof finishing materials, various equipment such as lighting, ceiling finishing, etc. on this triangular truss beam 1, prestressing is introduced by tensioning the PC steel rods 9. The prestress is introduced by sequentially fixing the PC steel rod 9 under tension to the fixing portion 6 provided at the lower end of the lattice material 5 to be joined using the nut 10. In this way, after constructing all the equipment, that is, triangular truss beam 1
Introducing prestress after setting the total load to , it is possible to introduce an accurate prestress commensurate with the load, and the effect of the present invention can be maximized. Once the prestress has been introduced into the triangular truss beam 1, it is slid on a guide rail attached to the girder of the structure and delivered by one truss onto the structure. After that, a new triangular truss beam 1 assembled on the ground is connected to this triangular truss beam 1 on the gantry using the connecting member 2, and the process of sending out two spans onto the structure is repeated, or the above-mentioned triangular truss beam By connecting the joining member 2, the upper limit member 3, and the lattice member 5 to the truss beam 1, and assembling the next adjacent triangular truss beam, the completed part is sequentially sent out onto the structure one span at a time. All you have to do is build a roof. Alternatively, an alternate triangular truss structure can be created by creating every other triangular truss beam 1 and connecting them with a connecting material.

In addition, if the roof has a structure having orthogonal triangular truss beams 1a as shown in Fig. 5, when sliding the triangular truss beam 1 onto the structure, the PC Pass the steel material (PC steel bar 9a in the example) through the fixed part 6a and bring it along with the triangular truss beams 1, and when all the triangular truss beams 1 have been moved, that is, the roof has been completely erected. , on the gantry, tension the prestressing steel material in one direction to introduce plastic stress, or install a gantry on the opposite side of the structure,
There is also a way to create tension from both sides. Regarding the triangular truss 1a that is orthogonal to the triangular truss 1, in principle, the fixing part 6a and the PC steel bar 9a are not fixed, but when using prestressing steel bars at regular intervals in the orthogonal direction, they are slid one after another and fed out. once in a while
There is a method of tensioning the PC steel rods 9a and fixing them to the fixing parts 6a.

Although the present invention has been described with respect to an inverted triangular truss using the above embodiments, the truss structure according to the present invention is not limited to the above-mentioned structures, and may have other characteristics such as a three-dimensional truss other than the lower chord member. It can also be used as a truss.

"Effects of the Invention" As explained above, according to the present invention, in a truss structure assembled in a truss shape by an upper chord member, a lower chord member, and a lattice member, the lower chord member itself is
Constructed of PC steel material, and this lower chord material
Since the PC steel material was fixed to the lower end joint of the lattice material under tension, the PC steel material
Not only does the tensile force generated by the load exert a resistance force on the lower end joints of the lattice materials, which attempt to open the gap, but the compressive force introduced by the prestressing steel material on the lower end joints of the lattice materials causes a tensile force due to the load. Deflection and deformation can be minimized by offsetting this.

Furthermore, during construction, we use the sliding method, in which the beams that make up the truss structure are successively sent out to the top of the structure at a predetermined location, and the split structure that makes up the parts of the truss structure. It has excellent effects, such as being able to use the unit construction method in which a truss structure is constructed by pre-assembling and connecting the truss structures.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is a partial front sectional view, FIG. 2 is a sectional view taken along line A-A' in FIG. 1, and FIG. 3b is a side view, FIG. 3b is a front sectional view of the fixing part 6,
Figure 4 is a side sectional view showing the bundled state of the PC steel rods 9;
FIG. 5 is a perspective view showing the orthogonal state of the triangular truss beams. 1...triangular truss beam, 2...joining member, 3...
Upper chord material, 4... Lower chord material, 5... Lattice material, 6...
Fixed part, 9...PC steel bar.

Claims (1)

[Claims] 1. In a truss structure constructed of a top chord, a bottom chord, and a lattice material assembled into a truss shape, the bottom chord itself is made of prestressing steel, and the prestressed steel making up the bottom chord is in a tensed state. A truss structure characterized by being fixed to a lower end fitting part of a lattice material.