JPH01207549A - Synthesized structure - Google Patents

Abstract

PURPOSE:To enhance resistance against crack initiation by using a shape steel having a straight web to a shape steel welded to one side of a steel plate as shear connector, and by consolidating the concrete on both sides of the shape steel. CONSTITUTION:A tee shape steel 2a having straight web provided with a semicircular hole 6 in the lower part of the web 4 is welded on a steel plate 1 as shear connector, and it is embedded in concrete 3. Because the concrete 3 on both sides of the web 4 is consolidated through the hole 6, a force due to dislocation willing to crack the concrete 3 will reduce greatly, which increases the resistance against crack initiation at the tip of flange 5 to a great extent.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a composite structure of steel plates and concrete, and is used for deck slabs in building structures, bridges, and other port structures such as caissons and immersed tunnels. be able to.

[Conventional technology]

In the composite structure of steel plate and concrete, the steel plate acts as a formwork before the concrete hardens, and after hardening, the concrete and steel plate are integrated to obtain a composite structure. In order to obtain this structure, it is necessary to ensure the inter-plate properties to absorb the pressure of the concrete during concrete pouring, and to ensure that the steel plates and concrete have a slip-preventing effect so that they become one piece after the concrete hardens. It is necessary to add it.

As a conventional technique, as shown in FIG. 14, there is a technique in which a section steel 2 such as an angle or T section is welded onto a steel plate 1.

Before the concrete 3 hardens, the shaped steel 2 has the function of a reinforcing rib to ensure the out-of-plane rigidity of the steel plate 1, and after the concrete 3 hardens, it is buried in the concrete 3 and forms a shear between the steel plate 1 and the concrete 3. Has the function of a connector.

[Problem to be solved by the invention]

However, the conventional synthetic structure described above has the following drawbacks.

■ Shape steel 2 causes a continuous and large internal defect (discontinuous part of concrete 3) from the steel plate 1 side surface of concrete 3 toward the inside of concrete 3, and when shearing force acts, shape steel 1 in concrete 3 'i12 is deformed so as to push out the defect from the surface. As a result, a large stress concentration occurs in the concrete 3 at the tip of the flange 5 of the section steel 2, and even under low stress, a rack 8 occurs as shown in Fig. 15, and sufficient proof strength may not be obtained. (See Kiyomiya et al., "Basic Mechanical Properties of Shear Connectors in Composite Structures," Proceedings of the 8th Annual Conference on Concrete Engineering, pp. 609-612, 1986).

■ From the viewpoint of interpolation efficiency, it is better to increase the number of supplementary ribs based on the shape m2 as much as possible and increase the interpolation interval. However, since it increases the defects in the concrete mentioned above, it is not possible to make the rib depth large (at most about 174 mm, which is the total thickness of the slab), and small steel sections 2 are often used, which is uneconomical. .

■ In order to receive the anti-slip force intensively on the section steel 2 as a shear connector, the web 4 root of the section steel 2 and the steel plate 1
A large stress concentration occurs in the weld.

Among these, the stress concentration (2) does not pose much of a problem if the anti-slip force is small. Therefore, this invention
The first objective is to eliminate the defects (2) and (2), and the second objective is to simultaneously solve the problem (2) when the anti-slip force is large.

[Means to solve the problem]

Hereinafter, an overview of the present invention will be explained with reference to drawings corresponding to embodiments.

As shown in FIGS. 1(a) and (b), this invention
Fi, shape m2 as a shear connector on one side of 1?
In this composite structure, the section steel 2 is embedded in concrete 3 by welding and welding, and the section steel 2 is a TF12a having a non-filled web.

Here, the shape Q2a having a non-filled web is an angle,
Shape t of channel steel, T-beam steel, H-beam steel, etc. This means that the web 4 of fA2 is made into a lattice shape, or the web 4 is formed with sixes.

Concrete 3 wraps around the non-light part of the web 4, and the concrete 3 on both sides of the web 4 is integrated into the shaped steel 2a.
Wrap around the flange 5 of. Therefore, the force that breaks the concrete 3 is significantly reduced, and the bearing strength generated by the crank from the tip of the flange 5 is significantly improved. Further, the larger the unfilled area of the web 4 is, the better from the viewpoint of integration. However, since the effect of eliminating dendritic defects in the concrete 3 is large, a sufficient practical effect can be obtained if the width is approximately 1/4 of the total cross section of the web 4 and has a size that allows coarse aggregate to pass through.

Furthermore, as shown in FIGS. 2(al) and (bl), by using a steel plate 1' with protrusions formed with a large number of protrusions 7 on the side in contact with the concrete 3, the shear force between the concrete 3 and the steel plate l' can be reduced. is transmitted by the bearing pressure of the abdomen of the protrusion 7. In this case, the shear deformation between the two becomes small, and the shear force borne by the shape ml" as a shear connector is greatly reduced, so the shape steel 1° Stress concentration at the root is alleviated.

〔Example〕

Next, the illustrated embodiment will be described.

In the embodiment shown in FIGS. 1(a) and 1(b), a non-filling shear connector M2a is welded onto a steel plate and embedded in concrete 3, and the shape E2a is a semicircular connector at the bottom of the web 4. A shaped hole 6 is provided, and the web 4 is inserted through this hole 6 through iTl.
The concrete 3 on both sides of is integrated.

In the embodiment fbl shown in FIG. 3(a), a shape m2b obtained by cutting a channel steel web into a honeycomb shape is used as a shear connector. As the base material, H-beam steel may be used instead of channel steel. The shaped steel 2b is required to have an out-of-plane bending interpolation effect of the steel plate 1 before the concrete 3 hardens, but this requires increasing the cross-sectional area of the flange 5;
It is efficient to increase the height of the rib as the auxiliary rib, that is, the height of the section steel 2b. Therefore, the original material is a section steel having a flange 5 and a web 4, and may be not only a rolled section steel but also a cold bent plate such as a C-chan or Z-section steel. When the web is cut into a honeycomb shape as in this example,
Since the rib thickness is larger than when simply dividing it in half, the interpolation effect also increases.

FIG. 4 shows an embodiment in which the present invention is applied to a so-called sand inch plate in which steel plates 1 are arranged on both sides. In the case of a filled material, the shape steel forms a surface notch in the concrete 3, so it cannot be taken very far (at most about 174 mm of the thickness of the plate), but in the case of a non-light filled material, the web of the shape steel 2a Since the concrete 3 covers the area 4 and confines defects caused by the shaped steel 2a inside, the fault of the shaped steel 2a can be increased without reducing the load-bearing capacity of the concrete 3. In this embodiment, the section steel 2a from the top
The shape m2a is arranged in such a way that the flange 5 of the section steel 2a from below is inserted between the flanges 5 of the shape steel 2a. In this case, the concrete 3 between both flanges 5 will be surrounded by steel material, resulting in a strong cell-reinforced composite structure.

Moreover, by making the shaped steel 2a non-filling, the effect of improving workability in terms of the surroundings of the concrete 3 (fillability) can also be obtained.

In the above embodiments, the holes 6 in the unfilled webs 4 of the steel sections 2a and 2b were open on the steel plate l side, but the holes 6 may be closed within the webs 4 at an angle of 6 degrees, as in the shape 1J2c in FIG. . By doing so, welding to the steel plate 1 can be continuous and linear, and workability can be improved.

Further, the section steel to be welded to the steel plate 1 may have upper and lower flanges 5, 5'', as in the section steel 2d shown in FIG. 6, and the web 4 may be made of a non-optical material.

The embodiment shown in Fig. 2 (al) is different from the embodiment shown in Fig. 1 (al, (bl) in that it uses a steel plate with protrusions 1° having a large number of small protrusions 7 formed on the surface in contact with the concrete 3. As shown in Figure 2(b), concrete 3 and steel plate 1
The protrusion 7 of the steel plate 1'' bears a part p of the shear force P between the steel plate 1'' and the stress concentration at the root of the shaped steel 2a, that is, at the welding position to the steel plate 1.degree.

If the shape steel 2a of the non-filled web is used, the spacing between the shapes m2a can be increased from the viewpoint of the bending rigidity of the steel plate. However, on the other hand, if the interval is increased, the shear preventing force applied to each section steel 2a increases, which is disadvantageous in terms of the shear preventing effect. If the plate has a small effect on the spread of the plate of the composite plate, that is, if the shear force is small with respect to the bending stress of the plate, and only a small force acts as a shearing force, then even if the spacing between the sections 2a is large, Sufficient anti-slip force can be ensured and it can be put to practical use.

However, when the anti-slip force, that is, the shear force that must be withstood becomes large, the spacing between the shapes 142a cannot be set too large in terms of securing the anti-slip strength, and the effect of using the non-optical material is reduced. Figure 2(a), (blO
In this example, a steel plate 1 with protrusions is used to compensate for this point.

Figure 7 shows the deformation state of the section steel 2 when the anti-slip force is applied to the shape i42 in the case where the steel plate l'' with projections is not used.
The base is subjected to more bearing pressure and the bending shear force, but deformation is concentrated at the base. The upper part of the shaped steel 2 plays the role of an anchor, and this part bears almost no force.

That is, the shear force P received from the concrete 3 is transmitted to the steel plate as a bearing force acting on the bending and shearing deformation portion of the web. The bearing pressure range is mainly determined by the strength ratio of the concrete 3 and the web, and decreases as the concrete strength increases, but is usually around hs = 2.5t, where t is the web thickness. The range is narrow.

The protrusion 7 of 1° on the steel plate plays the role of increasing this bearing pressure area, but for example, the protrusion 7 of 1.25t is
By arranging them in rows, the bearing area of two sections of steel will be newly added, and the effect will be great. However, unlike the case of the shape steel 2, the protrusion 7 does not have the anchoring effect of the flange, so it cannot flexibly bear the anti-slip force while undergoing large bending and shear deformation like the shape m2. It is not possible to increase the height of the protrusion unnecessarily. The concrete bearing force acting on the protrusion 7 must be elastically transmitted to each part of the steel plate, and the following restrictions are imposed on the protrusion shape.

Referring to Fig. 8 and considering the concrete maximum compressive stress FC as the bearing force, the bending moment MA and shear force QA per unit length at the root point A of the protrusion are hb MA=FC--2Q A= F c h b・”
”・(1) (However, hb is the height of the protrusion) Let the yield point of 1° of the steel plate be σ, and in order to make each proof stress less than the elastic proof stress, (however, b is the width of the protrusion) Therefore, since Fc is usually σ7, the above equation becomes one, and becomes:

Points B and B in Fig. 8 are subjected to shearing force and bending force in opposite directions, but considering that the protrusion interval is larger than the steel plate thickness t and the shearing force is smaller than the bending stress, If this is ignored, the bending stress M per unit length will be as follows. Similarly, in order to keep this stress under the elastic proof stress, it becomes: (5).

In a normal synthetic structure, Fc/σv = 0.1, so by substituting this, b≧0 from equations (3) and (5).
．． 55h h, ≦2.13t...
...(6) is obtained.

In addition, the distance between the protrusions must be wide enough to allow the concrete coarse aggregate to enter between the protrusions.

If the maximum diameter of the coarse aggregate is D and the distance between the tops of the protrusions is B (see Figure 9), then B≧2J "]] It is sufficient to set the seal = 3 pieces.

The shape or pattern of the protrusion 7 may be any shape or pattern as long as it falls within the above dimension range.

10 to 13 show various examples of patterns of the projections 7.

〔Effect of the invention〕

■ Concrete wraps around the non-light side of the web of the section steel as a shear connector, and the concrete on both sides of the web unite and wrap around the flange of the section steel, eliminating internal defects in the concrete, so that the section steel Crank generation from the flange tip is suppressed.

■ By using a steel plate with protrusions that has a large number of protrusions formed on the side that contacts the concrete, the shear force between the concrete and the steel plate is transmitted by the bearing pressure of the protrusion abdomen, reducing shear deformation. Therefore, the shear force borne by the shaped steel as a shear connector is significantly reduced, and stress concentration at the root of the shaped steel is alleviated.

[Brief explanation of the drawing]

Figures 1 (al) and (b) are a cross-sectional view in the right angle direction and a cross-sectional view in the longitudinal direction of the shaped steel, respectively, showing an embodiment of the present invention, and Figures 2 (al) and (b) show a steel plate with protrusions. Figures 3(a) and 3(b) are cross-sectional views in the longitudinal direction of the shaped steel and enlarged views showing its effects in the case where the shaped steel is used, respectively. A cross-sectional view of
Figure 4 is a sectional view taken in the direction perpendicular to the steel section, showing an example where both sides of the concrete are sandwiched between steel plates;
fbl indicates other embodiments. A cross-sectional view in the longitudinal direction of the steel and a cross-sectional view in the direction perpendicular to the shaped steel, FIG. 7th
The figure is a sectional view taken in a direction perpendicular to the shaped steel to explain the action of the anti-slip force on the shaped steel, Figures 8 and 9 are sectional views to explain the action of the steel plate with protrusions, and Figures 10 to 10 are Figure 13 shows an example of the shape of a protrusion on a steel plate with protrusions, and Figure 10 (a)
1) Figure 1 (al) Figures 12 and 13 are plan views, Figure 1O (bl, 1) Figure (b) is a cross-sectional view in the direction perpendicular to the section steel, Figures 14 and 15 1 is a vertical cross-sectional view showing a conventional example. 1... Steel plate, 1... Steel plate with protrusions, 2... Shaped steel,
3... Concrete, 4... Web, 5... Flange, 6... Hole, 7... Protrusion, 8... Crack Patent applicant Agent Sumitomo Metal Industries, Ltd.
Patent Attorney Satoshi Takemon Figure 1 Figure 2 Figure 3 (a) (b) Figure 4 Figure 14 Figure 15

Claims (2)

[Claims] (1) In a composite structure in which a plurality of section steels as shear connectors are welded to one side of a steel plate and the section steels are buried in concrete, the composite structure uses a section steel having a non-filled web as the section steel. . (2) The composite structure according to claim 1, wherein the steel plate is a protruded steel plate with a large number of protrusions formed on one side, and a shaped steel is welded to the protrusion-forming surface.