JPS63171947A - Three-dimensional truss beam having prestress introduced thereinto - 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 (Industrial Field of Application) The present invention relates to a three-dimensional truss beam into which prestress is introduced.

(Prior Art) In general, three-dimensional truss beams are extremely excellent beams for large-span buildings such as factory hangars, and are actually widely used in many large-span buildings.

(Problems to be Solved by the Invention) However, this type of three-dimensional truss beam is assembled by attaching many diagonal members between the upper and lower chord members, so the number of members and joints are large, and assembly is generally troublesome. Ta.

In addition, when bending materials such as beams, steel resists tensile force to the full allowable tensile stress, but when it comes to compressive force, it will buckle laterally before reaching the allowable compressive stress, so the cross section must be increased. However, the same is true for three-dimensional truss beams, and the larger the span, the more important is the cross-sectional design that emphasizes buckling.

Therefore, in consideration of these points, conventional three-dimensional truss beams have been constructed vertically symmetrically with the neutral axis as a boundary and mainly have a rectangular cross-section.

However, with such a configuration, tensile stress is generated at the inner lower end and outer upper end of the bending point at both ends where the bending stress is reversed, so the amount of steel used in these parts is considerably large, so the cross-sectional design may be wasted. I can't escape it.

Moreover, since there is a large amount of steel, assembly is complicated and material costs are high.

This invention was proposed in order to solve the above-mentioned conventional problems, and the purpose is to provide a three-dimensional truss beam that reduces the amount of steel material as much as possible and introduces prestress that allows for a significantly economical design. That is.

(Means for Solving the Problems) This invention provides a substantially triangular cross-section for the portion outside the both-end recursion points at which the bending stress of the three-dimensional truss beam at both end supports is reversed, and the cross-section for the inner portion from the both-end recursion points to be approximately an inverted triangle. Each section is composed of
The above object is achieved by installing tension members in a suspended manner between the supporting points at both ends.

(Embodiment) Hereinafter, the present invention will be described with reference to an illustrated embodiment. A three-dimensional truss beam 1 is constructed by attaching a plurality of diagonal members 4 between an upper chord member 2 and a lower chord member 3, and ,5
It is built in between.

The upper chord seat 2 is composed of two chord members 2a, 2a, and the chord members 2 inward from the recursion points C and C at both ends where the bending stress is reversed.
The chord members 2a and 2a are horizontally spaced apart from each other by a predetermined distance and extend parallel to each other, and the chord members 2a and 2a on the outside of the curved points at both ends are formed so as to gradually taper toward the tip, and have a predetermined length at the tip. The parts are completely integral.

A plurality of connecting members 7 are connected between the string members 2a, 2a,
They are attached at regular intervals in the longitudinal direction of 2a.

In addition, the lower chord material 3 has two chord materials 3a, like the upper chord material 2,
3a, the chord members 3a, 3a on the inside from the recursion point C9C at both ends are formed completely integrally as a single piece, and the chord members 3a, 3a on the outside from the recursion points C, C at both ends are formed in the tip direction. It is formed into two forks that gradually spread out. A plurality of connecting members 7 are connected between the string members 3a, 3a.
They are installed at regular intervals in the longitudinal direction.

The diagonal member 4 is attached between the upper chord member 2 and the lower chord member 3 between the chord members 2a and 3a.

The three-dimensional truss beam 1 configured in this way has curved points C at both ends.
, C has a substantially triangular cross-sectional shape, and both end inversion points C and C have a substantially inverted triangular cross-sectional shape.

In addition, tension members 6 such as PC&l wires are suspended between the left and right columns 5, 5 of the three-dimensional truss beam 1 along the lower chord 3 of the three-dimensional truss beam 1, and both ends of the tension members 6 are firmly fixed to the ground A. ing.

In such a configuration, the lower end of the inner beam and the upper end of the outer beam at both end curve points C and C of the three-dimensional truss beam 1 can resist tensile stress caused by external force to the full allowable stress level, so the tensile stress It is sufficient if there is a cross-sectional area that can resist. Furthermore, the tension member 6 bears the tensile stress exceeding the allowable stress.

On the other hand, the upper end portion of the inner beam at both end recursion points C and C and the lower end portion of the outer beam at both end recursion points C and C are upper chord member 2 and lower chord member 3.
Since the horizontal rigidity is increased by forming the string double from two chord members, it is difficult to apply lateral pressure, and the compressive strength is significantly increased.

Note that the diameter and number of chord members 2a+3a of the upper chord members 2 and lower chord members 3, and the installation interval of the diagonal members 4 are appropriately determined according to the size of the beam span.

(Effects of the Invention) Since the present invention has the above configuration, it has the following effects.

In consideration of the parts that require consideration of horizontal seating and the parts that do not, the outer part of the recursion points at both ends is configured to have an approximately triangular cross section, and the inner part of the recursion points at both ends is configured to have an approximately inverted triangular cross section. Therefore, there is no waste of materials, and it is possible to save a lot of steel and reduce the number of joints, making it possible to design economically.

Also, assembly work is extremely easy.

Furthermore, since tension members are installed in a suspended manner between the supporting points at both ends of the three-dimensional truss beam, the cross section of the lower chord member inside the recursion points at both ends can be reduced as much as possible, which is also an economical design. is possible.

[Brief Description of the Drawings] Figures 1 to 9 show an embodiment of the present invention, in which Figure 1 is a perspective view of a three-dimensional truss beam, Figure 2 is a side view thereof, and Figure 3 is a perspective view of a three-dimensional truss beam. is its top view, Figure 4 is its bottom view, and Figure 5 is its second view.
6 is a sectional view taken along line bb in FIG. 2, FIG. 7 is a sectional view taken along line cc in FIG. 2, and FIG. Figure 9 is a bending stress diagram of the beam material with supporting points at both ends. 1. Three-dimensional truss beam, 2. Upper chord member, 3. Lower chord member, 4
... Diagonal material, 5.. Column, 6.. Tension material, 7.. Connecting member. Fold 5 Fig. 6 Lock No. 7 River Fig. 8 Fig. 9

Claims (1)

[Claims] In a three-dimensional truss beam with fulcrums at both ends, the part outside the recursion point at both ends where the bending stress is reversed has a substantially triangular cross-section, and the part inside from the recursion point at both ends has a substantially inverted triangular cross-section, and tendons are placed between the supports at both ends. A three-dimensional truss beam that incorporates prestressing and is characterized by being installed in a suspended configuration.