Precast concrete slab

Abstract

To prevent damages to shear keys due to shear loads and prevent the shear keys from falling off in a damaged state for precast concrete slabs with ridges and grooves on the sides that are shear keys.SOLUTION: In a precast concrete slab 1, which has protruding parts 121, 122 on its sides that sandwich from above and below convex ribs 11 and concave grooves 12 that are shear keys, the convex ribs 11 and the protruding parts 121, 122 have built-in reinforcing materials 14, 15, 16 that extend in the protruding direction of the convex ribs 11 and the protruding parts 121, 122.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a precast concrete deck having shear keys on its sides. [Background technology]

[0002] Precast concrete deck slabs, which are road construction materials, are provided with shear keys (for example, convex and concave parts in a transferable relationship) on the sides that engage in the thickness direction of the slab for the purpose of simplifying alignment during installation and preventing unevenness and steps, as shown in Patent Document 1, for example. The shear keys disclosed in Patent Document 1 are ridges and engagement grooves that continue in the extension direction of the side surface (Patent Document 1

[0026] ). The shear keys are formed as stripes and grooves that continue in the extension direction of the side surface (Patent Document 1), or are formed intermittently in the extension direction of the side surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-062713 A Summary of the Invention [Problem to be solved by the invention]

[0004] When heavy vehicles pass over a road constructed with precast concrete decks, a large shear load is applied to the shear keys on the sides, which can cause the shear keys to break. If the damaged shear keys are lost, the purpose of preventing unevenness and steps is lost, and unevenness and steps will occur on the road, making it necessary to restrict or stop using the road. Therefore, we investigated how to prevent damage to shear keys due to shear loads in precast concrete decks with shear keys on the sides, and how to prevent the shear keys from falling off if they are damaged. [Means for solving the problem]

[0005] As a result of the study, we developed a precast concrete slab with a shear key on the side, characterized in that the shear key incorporates a reinforcing material extending in the protruding direction of the shear key. The shear key is a convex portion or a convex strip provided on the side of the precast concrete slab, or a protruding portion located above or below a concave portion or a concave groove into which the convex portion or the convex strip fits. The precast concrete slab of the present invention does not matter whether reinforcement is arranged within the slab body. The reinforcing material is a rod material with a length extending from the slab body of the precast concrete slab to near the tip of the shear key in the protruding direction, or a surface material that extends from the slab body of the precast concrete slab to near the tip of the shear key in the protruding direction.

[0006] The reinforcing rods are either an extension of the reinforcement built into the slab body, a separate body connected to the reinforcement, or a separate body independent of the reinforcement. The reinforcing surface material is either a separate body connected to the reinforcement, or a separate body independent of the reinforcement. Reinforcing surface material includes flat plates, perforated plates, mesh plates, as well as corrugated or curved plates and frames. The reinforcing rods or surface material may be used singly or in combination. When there are multiple reinforcing rods or surface material, they may extend in the same direction, but they are built in with spaces between them in the extension direction of the side surface.

[0007] Reinforcement materials used are metals, resins, and ceramics that have the structural strength to withstand shear loads. Metal reinforcement materials are an extension of the reinforcement built into the slab body, a separate body that connects to the reinforcement, or a separate body independent of the reinforcement. Resin or ceramic reinforcement materials are separate bodies that connect to the reinforcement, or a separate body independent of the reinforcement. When multiple reinforcement materials are used, the materials of each reinforcement material may be the same or different. When combining reinforcement materials that are rod materials or surface materials, the materials of each reinforcement material may be the same or different.

[0008] Shear keys with built-in reinforcing material can be reinforced with the reinforcing material up to the tip of the shear key in the protruding direction by having the reinforcing material built in while being exposed from the tip. The reinforcing material only needs to extend to the tip of the shear key in the protruding direction, so it is sufficient to expose the reinforcing material from the tip of the convex part with its end face flush with the tip of the convex part. For reinforcing materials made of metal that rust easily and with the reinforcing material exposed from the tip of the shear key in the protruding direction, at least the exposed part and the tip of the convex part where the reinforcing material is exposed are subjected to rust prevention treatment. For reinforcing materials made of resin or ceramics and with the reinforcing material exposed from the tip of the shear key in the protruding direction, rust prevention treatment is not required for the exposed part.

[0009] When a reinforcing material having a hook portion is built into a shear key having a built-in reinforcing material, the portion of the convex portion split by shearing is caught by the hook portion and does not separate from the main body of the convex portion. The hook portion may have a shape or size that allows the split portion of the convex portion to be caught. For a reinforcing material that is a bar material, the hook portion is a protrusion protruding from the surface of the bar material or a portion of the bar material with a thickened outer diameter. For a reinforcing material that is a bar material having a hook portion, for example, a deformed reinforcing bar can be used. For a reinforcing material that is a face material, the hook portion is not only a protrusion protruding from the surface of the face material or a portion of the face material with a thickened outer diameter, but also an opening or a number of holes provided in the face material. The hook portion may be formed by deforming a part of the reinforcing material, or may be attached to the reinforcing material as a separate body. Effect of the Invention

[0010] In the precast concrete deck of the present invention, the reinforcement built into the shear key does not shear the shear key against the shear load, thereby preventing damage to the shear key due to shear load and preventing the shear key from missing if it is damaged. If the reinforcement has a length or size from the tip of the shear key in the protruding direction to the exposed end, the shear key is prevented from being damaged by shear load up to the tip, and the shear key is prevented from missing if it is damaged. Furthermore, if the reinforcement is provided with a hook portion, it is possible to better prevent the shear key from missing if it is damaged. The hook portion also serves to increase the fixing effect of the reinforcement at the convex portion. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view of the precast concrete floor slab of this example, viewed from the front side. [Diagram 2] FIG. 2 is a perspective view of the precast concrete floor slab of this example, viewed from the rear side. [Diagram 3] FIG. 2 is a perspective view equivalent to FIG. 1, showing the slab body of the precast concrete floor slab of this example with virtual lines and showing the reinforcement. [Figure 4] FIG. 3 is a perspective view equivalent to FIG. 2, showing the slab body of the precast concrete floor slab of this example with virtual lines and showing the reinforcement. [Diagram 5] FIG. 4 is an enlarged view of the portion indicated by the arrow A in FIG. [Figure 6] FIG. 5 is an enlarged view of the portion indicated by the arrow B in FIG. [Figure 7] FIG. 5 is an enlarged view of the portion indicated by the arrow C in FIG. [Figure 8] FIG. 2 is a partial cross-sectional view showing two precast concrete floor slabs of this example connected together. [Figure 9] 8 and shows a first modified example in which a hook portion is formed by processing a part of a reinforcing material. FIG. [Figure 10] 8 and shows a second modified example in which the reinforcing material is an extended truncated cone or a cylindrical body fitted onto the reinforcing material is used as the hook portion. FIG. [Figure 11] FIG. 10 is a view equivalent to FIG. 8 of Modified Example 3 in which a flat plate provided at the end of a reinforcing material serves as a hook portion. [Figure 12] This is an oblique view from the front side of a precast concrete floor slab of Alternative Example 4, in which convex portions and concave portions that are in a transferable relationship are arranged in the same row. [Figure 13] FIG. 13 is a perspective view equivalent to FIG. 12, showing the slab body of the precast concrete floor slab of Alternative Example 4 with imaginary lines and showing the arrangement of reinforcement. [Figure 14] FIG. 14 is an enlarged view of the portion indicated by the arrow D in FIG. [Figure 15] FIG. 14 is an enlarged view of the portion indicated by the arrow E in FIG. [Figure 16] A partial cross-sectional view showing the state in which two precast concrete floor slabs of Alternative Example 4 are connected. [Figure 17] FIG. 15 is a view equivalent to FIG. 14 of Modified Example 5 in which the reinforcing material is formed into two oblique frame bodies. [Figure 18] FIG. 14 corresponds to FIG. 14 but shows a sixth modified example in which the reinforcing material is a corrugated plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiment of the present invention will be described with reference to the drawings. The present invention is applied to a precast concrete slab 1, which is generally rectangular in plan view and connected in the short side direction, as shown in Figs. 1 to 4. The precast concrete slab 1 of this example is configured such that the convex strips 11 and the concave grooves 12 constituting the shear key are assigned to the side surfaces in the longitudinal direction of the slab body 13, which incorporates short reinforcing bars 133, which are steel bars wound in the short side direction, and long reinforcing bars 134, which are extended in the longitudinal direction along the inner periphery of the short reinforcing bars 133. For convenience of explanation, the side surface on which the convex strips 11 are provided will be called the "front surface" and the side surface on which the concave grooves 12 are provided will be called the "back surface."

[0013] The slab body 13 has three connecting parts 132 at equal intervals in the longitudinal direction at each of the upper front corners and the upper rear corners. The connecting parts 132 are formed by closing the openings on the front or rear side of the cutouts that straddle the upper front corners or the upper rear corners with metal connecting plates with oblique holes. Adjacent precast concrete slabs 1 are connected by tightening connecting bolts passed through the oblique holes of the corresponding connecting parts 132 on the opposing front and rear sides with connecting nuts. In the precast concrete slab 1 of this example, angle members 131 are fixed to the upper front corners and the upper rear corners between the connecting parts 132 to prevent damage to the upper front corners or the upper rear corners.

[0014] The convex rib 11 is a portion in which a convex portion with a trapezoidal cross section protruding in the short direction of the plate body 13 extends in the longitudinal direction, located in the middle portion of the front surface divided into approximately three equal parts in the vertical direction (see FIG. 8 below). The concave groove 12 is a portion in which a concave portion with a trapezoidal cross section extends in the longitudinal direction, located in the middle portion of the back surface divided into approximately three equal parts in the vertical direction and sandwiched between upper and lower protruding portions 121, 122 protruding in the short direction of the plate body 13 (see FIG. 8 below). The concave groove 12 has a transferred shape of the cross-sectional shape of the convex rib 11, and is provided at a height where the convex rib 11 fits in just right. The convex rib 11 and the concave groove 12 in this example are each continuous in the long direction of the plate body 13, but they may be provided intermittently to avoid the connecting portion 132.

[0015] In this example, the protrusions 121 and 122 sandwiching the convex bar 11 and the concave groove 12 are shear keys. The reinforcement 14 built into the protrusion 11 is a separate steel bar attached in parallel to the horizontal part of the short reinforcement 133 in the middle of the vertical part on the front side of the short reinforcement 133, as shown in Figure 5. The reinforcement 15 built into the protrusion 121 or the protrusion 122 is a separate steel bar attached to the extension of the horizontal part of the short reinforcement 133, as shown in Figures 6 and 7, and the reinforcement 16 built into the protrusion 121 or the protrusion 122 is a separate steel bar attached to the bend between the horizontal and vertical parts of the short reinforcement 133 in the extension direction of the horizontal part. The protrusions 121 and 122 alternate the reinforcements 15 and 16 assigned to adjacent short reinforcements 133.

[0016] As shown in FIG. 8, the precast concrete deck 1 of this example is connected by fitting the convex strip 11 provided on the front of the deck body 13 into the concave groove 12 provided on the back of the deck body 13. The gap between the front and back faces may be left as it is or may be filled with grout material (joint material). In either case, the convex strip 11 and the protrusions 121, 122, which serve as shear keys, overlap in the vertical direction, and a shear load is applied, for example, every time a vehicle passes over the top. At this time, the reinforcing members 14, 15, 16 built into the convex strip 11 and the protrusions 121, 122 resist the shear load, preventing damage to the convex strip 11 and the protrusions 121, 122 and preventing the damaged convex strip 11 and the protrusions 121, 122 from falling off.

[0017] As shown in FIG. 9, the precast concrete floor slab 1 of the modified example 1 is provided with a fin-shaped hook 141 formed by crushing a part of the reinforcement 14, and the reinforcement 15, 16 is provided with hooks 151, 161 made of annular grooves, thereby preventing the missing ridge 11 and protrusions 121, 122 from being separated from the main body. The fin-shaped hook 141 is a structure that protrudes from the reinforcement 14. The hooks 151, 161 made of annular grooves are a structure that is recessed from the reinforcement 15, 16. The hooks 141, 151, 161 also serve to enhance the fixing effect of the reinforcement 14, 15, 16 at the ridge 11 and protrusions 121, 122. The hooks 141, 151, 161 of the reinforcement 14, 15, 16 may be assigned differently, or all of them may be the same hooks 141, 151, 161.

[0018] As shown in FIG. 10, the precast concrete floor slab 1 of the modified example 2 prevents the missing ridges 11 and protrusions 121 and 122 from being separated from the main body by using a cylindrical body fitted on the outside of the reinforcing material 14 as the hook 142 and a truncated cone block attached to the tip of the reinforcing material 15 and 16 as the hook 152 and 162. The reinforcing material 14 of the modified example 2 is subjected to rust prevention treatment and has a length that is exposed on the surface of the reinforcing material 11, reinforcing the reinforcing material 11 to the tip. The hook 142, which is a cylindrical body, is a member that uniformly expands the outer diameter of the reinforcing material 14. The hook 152 and 162, which are truncated cone blocks, are members that gradually expand the outer diameter of the reinforcing material 15 and 16. The hook 142, 152 and 162 also serve to enhance the fixing effect of the reinforcing material 14, 15 and 16 at the reinforcing material 11 and the protrusions 121 and 122. The allocation of the hook portions 142, 152, 162 of the reinforcing members 14, 15, 16 may be changed, or all of the hook portions 142, 152, 162 may be the same.

[0019] As shown in Fig. 11, the precast concrete slab 1 of the modified example 3 uses flat steel plates attached to the ends of the reinforcing members 14, 15, 16 as the hooks 143, 153, 163 to prevent the missing ridges 11 and protrusions 121, 122 from being separated from the main body. The hooks 143 attached to the ends of the reinforcing members 14 are exposed to the surface of the reinforcing members 11 after being subjected to an anti-rust treatment, and the reinforcing members 14 that reach the surface of the reinforcing members 11 reinforce the reinforcing members 11. The hooks 143, 153, 163 use the reinforcing members 14, 15, 16 as anchor members. The hooks 143, 153, 163 also serve to enhance the fixing effect of the reinforcing members 14, 15, 16 at the reinforcing members 11 and protrusions 121, 122. The reinforcing members 14, 15, and 16 may have the exposed hook portion 142 changed to hook portions 152 and 162, or may be entirely exposed or not exposed at all.

[0020] The present invention is also applicable to a modified example 4 in which the convex parts 21 and the concave parts 22 constituting the shear keys are arranged alternately in the same row on the longitudinal side of the slab body 23 in a precast concrete slab 4 in which the short reinforcements 233, which are steel bars wound in the transverse direction and have a rectangular shape in plan view connected in the transverse direction, and the long reinforcements 234, which are steel bars extended in the longitudinal direction along the inner periphery of the short reinforcements 233, are built into the slab body 23 as seen in Figures 12 and 13. For convenience of explanation, the longitudinal side of the slab body 23 visible in Figure 12 is called the "front side," and the longitudinal side of the slab body 23 hidden in Figure 12 is called the "back side."

[0021] The slab body 23 has three connecting parts 232 at equal intervals in the longitudinal direction at each of the upper front corners and the upper rear corners. The connecting parts 232 are formed by closing the openings on the front or rear side of the cutouts that straddle the upper front corners or the upper rear corners with metal connecting plates with oblique holes. Adjacent precast concrete slabs 1 are connected by tightening connecting nuts to connecting bolts passed through the oblique holes of the corresponding connecting parts 232 on the opposing front and rear sides. The precast concrete slab 2 of Alternative Example 4 has angle bars 231 fixed to the upper front corners and upper rear corners between the connecting parts 232 to prevent damage to the upper front corners or upper rear corners.

[0022] The convex portion 21 is a trapezoidal portion in plan view that protrudes in the short direction of the plate body 23 from the lower portion that divides the front or back surface approximately in half in the vertical direction. The concave portion 22 is a trapezoidal portion in plan view that is recessed in the short direction of the plate body 23 from the lower portion that divides the front or back surface approximately in half in the vertical direction. The convex portions 21 and the concave portions 22 have a transferable shape in plan view, and are alternately arranged in the same row so that the convex portions 21 fit exactly into the concave portions 22. For this reason, the arrangement of the convex portions 21 and the concave portions 22 on the front surface is reversed to the arrangement of the convex portions 21 and the concave portions 22 on the back surface.

[0023] In the fourth modification, the convex portion 21 and the overhanging portion 221 above the concave portion 22 are shear keys. The reinforcement 24 built into the overhanging portion 221 is a steel frame of a separate member attached parallel to the horizontal portion of the short reinforcement 133 so as to surround the middle of the vertical portion of the short reinforcement 133 as shown in FIG. 14, and the entire structure functions as a hooking portion as concrete is embedded in the frame. The reinforcement 26 built into the convex portion 21 is a punching metal of a separate member arranged parallel to the horizontal portion of the short reinforcement 133 and parallel to each other so as to sandwich the vertical portion of the short reinforcement 133 as shown in FIG. 15, and the entire structure functions as a hooking portion as concrete is embedded in a large number of holes. The reinforcement 24, 26 may be interchangeable with the built-in convex portion 21 and overhanging portion 221. The reinforcement 24, 26 may also be built into the convex portion 21 and overhanging portion 221 with the same configuration.

[0024] As shown in FIG. 16, the precast concrete floor slab 2 of the modified example 4 is connected by fitting a convex portion 21 provided on the front of the slab body 23 with a concave portion 22 provided on the back of the slab body 23. The gap between the opposing front and back faces may be left as a gap or may be filled with grout material (joint material). In either case, the convex portion 21 and the overhang portion 221, which serve as shear keys, overlap in the vertical direction, and a shear load is applied, for example, every time a vehicle passes over the top surface. At this time, the reinforcing members 24, 26 built into the convex portion 21 and the overhang portion 221 resist the shear load, preventing damage to the convex portion 21 and the overhang portion 221 and preventing the damaged convex portion 21 and the overhang portion 221 from falling off.

[0025] As shown in Fig. 17, the precast concrete floor slab 2 of Alternative Example 5 has two steel frames that are mirror-symmetrically positioned across the middle section of the vertical section of the short reinforcement 133, each of which serves as a reinforcement 25. The reinforcement 25 is a frame that is oblique to the horizontal section of the short reinforcement 233, and the entire frame acts as a retaining member as concrete is bitten into the frame, preventing the missing section of the overhang 221 from separating from the main body. When multiple reinforcements 25, which are oblique frames, are arranged on the same overhang 221, they may each have a different oblique angle, and may each be curved rather than linear.

[0026] As shown in Fig. 18, the precast concrete slab 2 of Alternative Example 6 has two corrugated steel plates arranged in a mirror-symmetrical relationship across the middle of the vertical part of the short reinforcement bars 133, each of which serves as a reinforcement 27. The reinforcement 27 is a plate material with a curved cross section in the longitudinal direction of the slab body 23 along which the long reinforcement bars 234 extend, and the concrete bites into the plate in accordance with the curve, so that the entire reinforcement acts as a retaining part, preventing the missing protrusion 21 from separating from the body. When multiple reinforcement members 25, which are corrugated plates, are arranged on the same overhanging part 221, the size of the corrugations may be different for each reinforcement member, and multiple holes may be provided in consideration of the flow of concrete around the plate. [Explanation of symbols]

[0027] 1 Precast concrete deck 11 Convex strip 12 Groove 121 Upper protrusion 122 Lower protrusion 13 Edition main body 131 Angle iron 132 Connecting part 133 Short-Term Arrests 134 Long-Term Arrests 14 Reinforcement material on the front side 141 A fastening part formed by crushing the side of a reinforcement material 142 A hook consisting of a cylindrical body fitted to a reinforcing material 143 A flat plate-shaped fastening portion at the end of the reinforcement 15 Reinforcement material extended from short reinforcement bars on the rear side 151 A retaining portion consisting of an annular groove provided in a reinforcing material 152 A hanging part consisting of a truncated cone with an extended reinforcement 153 A flat plate-shaped fastening part at the end of the reinforcement 16 Reinforcement material on the rear side 161 A retaining portion consisting of an annular groove provided in a reinforcing material 162 A hanging part consisting of a truncated cone with an extended reinforcement 163 A flat plate-shaped fastening portion at the end of the reinforcement 2 Precast concrete deck 21 Convex 22 Recess 221 Protruding part above the recess 23 Edition main body 231 Angle iron 232 Connecting part 233 Short-Arrested 234 Long-Term Arrests 24 Reinforcement for overhanging sections 25 Reinforcement for overhanging sections 26 Reinforcement for convex parts 27 Reinforcement for convex parts

Claims

1. In a precast concrete deck with shear keys on the sides, A precast concrete deck slab characterized in that the shear key has built-in reinforcing material extending in the protruding direction of the shear key.

2. 2. A precast concrete deck according to claim 1, wherein the shear key is built-in with the reinforcing material exposed at its tip.

3. 2. A precast concrete deck according to claim 1, wherein the shear key incorporates a reinforcing member having a hook portion.

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