JPH01290857A - Composite beam of steel material and concrete - Google Patents

Abstract

PURPOSE:To improve fire-proof performance in a beam using H-steels as chief members by placing concrete in recessed grooves on both sides between a web and flanges to form a composite beam. CONSTITUTION:Concrete 2 is placed in recessed grooves on both sides between the web 11 and flanges 12 of an H-steel 1, being formed in a body by using connecting members 20 of a steel material. In a composite beam B of a steel material and concrete thus formed, the whole surface except the outer faces of the flanges 12 is covered with concrete, having a large heat capacity of the concrete. Hence, the temperature rise of the flange portion can be also restrained improving heat-proof performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the fireproof structure of beams, and particularly relates to a precast concrete composite beam with a fireproof structure composed of H-shaped steel and concrete.

[Prior art] In a general building, columns and beams are the main structural members, and they need to be fireproof, and when the main material is steel, it is necessary to cover them with fireproof coating. For some reason, the seventh
As shown in the figure, they were constructed of steel-framed reinforced concrete, or they were covered with fireproof material as shown in Figures 8 and 9. In the diagram, 1 is steel frame, 2 is concrete, and 3
is the reinforcing steel, 4 is the mortar, and 5 is the precast concrete plate.

However, this fireproof coating is difficult to prevent when the temperature of the steel frame is, for example, 45
As the idea that it is sufficient to maintain its role as a structure even when the temperature exceeds 0°C has become established, it is now possible to effectively design steel frames such as columns and beams by placing superior materials on the outside of the cross section. became.

In foreign countries, there are cases where concrete blocks have been certified to be fire resistant for 30 minutes by simply installing concrete blocks in the grooves on both sides of the steel frame 1, and a structure in which the bottom surface of the deck plate is left uncovered even if it is a slab is now in practical use. It's coming in.

[Problem to be solved by the invention] Since columns and beams of conventional steel structures must be fireproof, it is necessary to use steel-framed reinforced concrete construction from the viewpoint of materials and labor during construction. It was said that there was not much difference in construction costs from pure steel construction. Fireproof coating increases the dimensions of the structure, determines the ceiling height, increases the floor height, and therefore, when subject to building height restrictions, the number of floors is small and uneconomical, and the building plan itself was affecting. The present invention aims to rationalize the fireproof structure of steel frames, improve cross-sectional performance, especially in beam structures, and make it possible to provide them as members.

[Means for Solving the Problems] In view of the above-mentioned current situation, the present invention improves fire resistance by making the beam structure mainly made of H-shaped steel, but by making it a composite beam with concrete. The aim was to create a precast concrete composite beam with advantageous cross-sectional performance by combining it with concrete without using a covering material, and in order to achieve this. The method of this method is to pour concrete into the grooves on both sides between the web of the H-shaped steel and the flange in a beam whose main material is H-shaped steel, and to integrate it using a steel connecting member. It is characterized by forming a composite beam with concrete to create a fire-resistant beam member.

As a result, the composite beam of the present invention not only allows the steel frame portion to have a fireproof structure, but also has significantly improved fireproof performance when combined with concrete, achieving the result of eliminating all the deficiencies of conventional fireproof structures. It is something.

[Example 1] An example of a composite beam of steel and concrete according to the present invention will be described in detail based on the drawings. FIG. 1a is a side view of a composite beam shown in a standard structure, FIG. 1 is a sectional view thereof, and FIGS. 2 to 4 are sectional views of other embodiments. Reference numbers in FIGS. 7 to 9 are common to corresponding parts. In FIGS. 1a and 1b, B is a part of the composite beam of the present invention, which is made up of a steel frame 1 and concrete 2. The steel frame 1 is an H-shaped steel, and both sides of the web 11 have
As a connecting member 20 between the steel frame 1 and the concrete 2, stud bolts 21 are welded and installed laterally at predetermined intervals. A reinforcing bar 3 may be strung across the tips of these stud bolts 21 in the axial direction of the H-shaped steel.

Other examples of the connection member 20 are shown in FIG. 2 and below, and in FIG.
are welded and fixed, and axial reinforcing bars 3 are strung across these reinforcing bars 22 to connect the H-shaped fil and concrete 2.
This is to further strengthen the bond between Japan and Japan. Figure 3 shows the iron example 1)
? This is an example in which the i22 is welded to the web 11 side to form stirrup-shaped reinforcing bars 23, and in this example, there are two reinforcing bars 3 in the axial direction, one above the other. FIG. 4 shows an example in which the steel frame 1 is made into an H-shape by connecting two channel steels 1a, 1a back to back, and a normal bolt 24 is used in place of the stud bolt 21 in FIG. Double-groove type 11a by the nut,
This is an example in which it is also used for bonding 1a.

FIG. 5 shows a further embodiment in a perspective view. In this example, the ribs 25 of the entire cross-section are fixed, leaving the connection part with the column 6 at the end of the H-shaped steel 1, and the concrete 2 is filled inside where they face each other. Then, the prestress cable 30 is routed using these ribs 25 as fixing plates at both ends, and prestress is introduced into the H-shaped steel 1 and the concrete 2 integrally, and the composite beam B is prestressed.
It forms a concrete beam. Of course, any type of connection member described above can be used in combination so that the H-shaped steel 1 and the concrete 2 act together.

[Function] The function of the steel and concrete composite beam of the present invention having the above-mentioned configuration will be explained based on its manufacturing method. FIGS. 6A, 6B, and 6B are process diagrams. First, stud bolts 21 are implanted into the H-shaped steel 1 as an example of the connection member 20 on both sides of the web 11 at appropriate intervals. Next, as shown in figure a, the flanges 12 are vertically placed in parallel on the surface plate 7, and concrete 2 is placed between the web 11 and the flange 12.
to be poured. As a result, the concrete 2 is filled integrally with the H-shaped steel 1, and the H-shaped steel 1 and the concrete 2 are connected. Next, as shown in figure b, the H-shaped steel 1 is turned upside down, and concrete 2 is placed on the other side of the web 11 in the same way to complete the composite beam B of steel and concrete, and the composite zB is This will be a beam member with precast concrete. At this time, the H-shaped steel 1 and the concrete 2 are integrated by the connecting member 20.

It is preferable to mix a shrinkage compensating agent into the concrete 2 to prevent the two from peeling off.

The other examples of composite beams shown in FIGS. 2 to 4 are manufactured in the same manner. In the example of using prestressed concrete shown in Fig. 5, an unbonded cable is used as the prestressed cable 30, and it is wired before concrete 2 is poured, and prestressing is introduced after it hardens and cures. . In the composite beam B, stress is applied to the H-shaped steel 1 and the concrete 2 at the same time, and it is possible to give "swelling", so even if the composite beam B has the same shape as the previous example, it is very advantageous in terms of structural design.

The composite beam B made of steel and concrete formed in this way is covered entirely with concrete except for the outer surface of the flange, and since the concrete has a large heat capacity, the temperature rise at the flange part is also eligible under regulations. be able to.

Furthermore, it goes without saying that the composite material of steel and concrete of the present invention is not limited to beams, but can also be used as columns.

[Effect of the invention] As mentioned above, the composite beam of steel and concrete of the present invention is a beam whose main material is H-shaped steel, and in which concrete is poured into the grooves on both sides between the web of the H-shaped steel etc. and the flange. It is an exceptional material as a connection member between steel and concrete because it is poured and integrated using a steel connection member to form a composite beam of steel and concrete to create a fire-resistant beam member. It is possible to construct a fire-resistant structure with simple processing without requiring any additional work, eliminating the need for troublesome fire-resistant coatings, and concrete can be poured continuously by using the parallel steel materials themselves as formwork. Therefore, the cost of constructing a fireproof structure is low.

Furthermore, by synthesizing and integrating the steel frame and concrete, buckling, which is the weak point of steel materials at high temperatures, is prevented, and a fire-resistant structure that maintains the performance of the structure is obtained. The cross-sectional properties can be significantly improved, and the performance against bending and deflection is improved. Therefore, it has a direct effect on the overall height of the building,
Building planning, as it increases the efficiency of building space usage.
Enables significant cost savings to the design. Moreover,
Since it can be manufactured as a precast beam member, it also makes it possible to shorten the construction period and reduce labor costs, producing novel effects that greatly contribute to the construction industry.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, FIG. 1 shows a composite beam of the present invention, FIG. a is a side view, FIG. b is a sectional view, and FIGS. Example, FIG. 5 is a perspective view of still another example in which prestress is applied, FIG. 6a,
b is a manufacturing process diagram, and FIGS. 7 to 9 are cross-sectional views illustrating a conventional fireproof structure. 1... Steel frame, H-type steel, 1a... Channel steel, 2... Concrete, 3... Rebar, 6... Column, 7... Surface plate, 11... Web, 12...・Flange, 20...
Connection member, 21... Stud bolt, 22.23...
・Reinforcing bar, 24... bolt, 25... rib, fixing plate,
30... Prestress cable, B... Composite beam. Figure 1 (G) (b) I H type #I
21 Stud bolt 2 ]″/Q
Re/Q REET 22 Side U leak 3 Rebar
23 Reinforcing bar 20 Connection member 24
Bolt B @Seiyo Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) For beams whose main material is H-shaped steel, concrete is poured into the grooves on both sides between the web of the H-shaped steel and the flange, and the steel and concrete are integrated using steel connecting members. A composite beam made of steel and concrete, characterized in that it is made into a fire-resistant beam member by forming a composite beam with steel and concrete. (2) The composite beam of steel and concrete according to claim 1, wherein the concrete is prestressed.