JP7526418B2 - Joint Structure - Google Patents

Description

The present invention relates to a joint device and joint structure used to connect components used in constructing a structure, for example, to connect precast concrete components.

In modern cities, when constructing structures such as buildings and various underground structures, a known technique is to transport prefabricated concrete components from a factory to the site and construct columns and beams by combining the components together or by assembling them with existing components. It is also known that tunnels are constructed by connecting multiple segments adjacent to each other in the circumferential direction.

Various connecting means are used to connect various components together. For example, Patent Document 1 discloses a technique for using a joint as a connector for connecting segments by combining a fitting member and a fitted member. Also, for example, Patent Document 2 discloses a cotter-type joint device for fastening segments and various concrete members. These connecting means have the effect of maintaining a strong connection state as well as facilitating workability (removal).

Patent No. 4344551 Patent No. 3787576

As typified by the connector described in Patent Document 1, it is known to mold the anchor member and the fitting body or fitted body as one piece and produce them as a casting. However, when the structure to be constructed becomes larger, it becomes necessary to increase the length of the entire part, which may make it difficult to mold them as one piece as a casting. In addition, when the connecting member is to be lengthened, it is possible to integrate the anchor member and fitting member, which are manufactured as separate parts, with screws or the like, but there are concerns about an increase in the number of parts and rising costs.

In addition, in the joint device described in Patent Document 2, in order to avoid lengthening the anchor member, a grip portion (support portion) is formed at the tip of the anchor member to increase the anchoring force. However, in such a configuration in which a grip portion is formed on the anchor member, there is a problem in that when a large anchor pull-out force is applied to the joint device, stress is concentrated in the grip portion, causing cracks in the structure (concrete, etc.).

In view of the above, the object of the present invention is to provide a joint device that can be integrally molded as a casting by suppressing the length of the component, and that ensures the anchoring force of the connecting component.

In order to achieve the above-mentioned object, according to the present invention, there is provided a joint structure formed by connecting a pair of coupling devices, the coupling device comprising : a connecting member that is embedded in precast members and is used to connect a pair of the precast members together, and that connects the pair of coupling devices together when the pair of coupling devices are butt-jointed; and an anchor member that is fixed inside the precast members and prevents the coupling device from being pulled out of the precast members, the precast members being segments or decks, and the anchor member being a rod-shaped member having a shape that does not expand in the thickness direction of the segment or deck, but gradually expands in diameter in the width direction as it moves from one end, which is a connection portion with the connecting member, to the other end, the coupling structure being formed by connecting a pair of coupling devices, the one coupling device comprising a male member as the connecting member, and the other coupling device comprising a female member as the connecting member, the pair of precast members being connected together by fitting the male member into the female member .

The connecting member and the anchor member may be integrally formed cast or forged members.

The present invention provides a joint device that can be molded as a single piece by suppressing the length of the component, and that ensures the anchoring force of the connecting member.

FIG. 1 is a schematic explanatory diagram showing an example of a conventional joint device used to join precast members together. FIG. 13 is a schematic explanatory view of a single member of a conventional joint device. FIG. 11 is a schematic explanatory diagram showing another form of a conventional joint device used to join precast members together. FIG. 13 is a schematic explanatory view of a single member of a conventional joint device. FIG. 2 is a schematic explanatory view of a single member of a joint device according to an embodiment of the present invention. FIG. 4 is a schematic explanatory diagram of a pull-out resistance force F of the anchor member according to the present embodiment. FIG. 2 is a schematic explanatory diagram of a first connection form. FIG. 11 is a schematic explanatory diagram of a second connection form.

The following describes an embodiment of the present invention with reference to the drawings. Note that in this specification and the drawings, components that have substantially the same functional configuration may be denoted by the same reference numerals to avoid redundant description.

(Conventional coupling device)
When constructing general concrete structures such as buildings and tunnels, construction is carried out by connecting multiple precast concrete members (hereinafter also simply referred to as precast members). In addition, in flat structures used for paving large areas such as airport parking areas and taxiways, construction is carried out by connecting multiple flat precast members laid on the roadbed.

Figure 1 is a schematic diagram showing an example of a conventional joint device 1 (hereinafter, joint device 1) used to connect precast members, showing a pair of butted joint devices 1 (1a, 1b) constructed and connected using an H-shaped member 5. Figure 2 is a schematic diagram of a single member of the joint device 1, (a) being a schematic plan view and (b) being a schematic side view. As shown in Figures 1 and 2, the joint device 1 is composed of C-shaped parts 10 (10a, 10b) as mated bodies and cylindrical members 11 (11a, 11b) as anchor members. The C-shaped parts 10 and cylindrical members 11 are integrated by a connecting means such as a screw mechanism to form the joint device 1.

As shown in FIG. 1, when connecting adjacent precast members P1 and P2 using a pair of joint devices 1a and 1b, the joint devices 1a and 1b are embedded inside the precast members P1 and P2 with the C-shaped parts 10 exposed. At this time, the cylindrical members 11 are embedded inside the precast members P1 and P2 so as to be fixed (fixed) to the concrete constituting the precast members P1 and P2. Then, the H-shaped member 5 is inserted into the fitting space S formed by butting the pair of C-shaped parts 10a and 10b, and the bolts 14 (14a, 14b) are inserted into the bolt holes 13 (13a, 13b) formed in the H-shaped member 5 and engaged with the bottom of the C-shaped part 10. Then, a time-hardening material such as mortar or a cover member (not shown) is applied to the connecting portion including the fitting space S as necessary. This fixes the H-shaped member 5 in a fitted state to the C-shaped components 10a and 10b, joining the precast members P1 and P2.

Figure 3 is a schematic explanatory diagram showing another form of a conventional joint device 1 (hereinafter, joint device 1') used to join precast members. Figure 4 is a schematic explanatory diagram of a single member of joint device 1', (a) being a schematic plan view and (b) being a schematic side view. In the joint device 1' shown in Figures 3 and 4, the common components such as the C-shaped part 10 are the same as those shown in Figures 1 and 2 above, so they are shown with the same reference numerals and their description is omitted.

As shown in Figures 3 and 4, the joint device 1' is provided with an anchor member 20 that is molded integrally with the C-shaped part 10, with the C-shaped part 10 at one end in the longitudinal direction of the anchor member 20 and a grip part 21 at the other end. Ribs 24 are provided on the surface of the anchor member 20. Here, the anchor member 20 is approximately cylindrical in shape, and the grip part 21 has an approximately disk shape with a larger diameter than the anchor member 20, and has a predetermined thickness in the longitudinal direction of the member.

(Issues with conventional joint devices)
In the conventional joint device 1 configured as described above with reference to Figures 1 and 2, the cylindrical member 11 needs to have a certain length in terms of design considerations regarding the reaction force against pulling out of concrete (so-called anchor force), and the member becomes long. The anchor force due to adhesion to concrete is calculated as the product of the circumferential area and the length of the anchor part (here, the cylindrical member 11). It is known that the adhesion force of concrete is small, less than 1/10 of the compressive force of concrete, and there is also a design limit to the diameter (i.e., circumferential area) of the anchor part, so that the anchor part needs to be long.

For this reason, it is difficult to manufacture the entire joint device 1 as a single piece using one-piece casting, which has manufacturing dimensional constraints. Therefore, the C-shaped part 10 and the cylindrical member 11 are manufactured as separate parts as castings. As shown in Figure 2, the longitudinal length L1 of the cylindrical member 11 is designed to be, for example, about 450 mm.

In the joint device 1, if the C-shaped part 10 and the cylindrical member 11 are manufactured as separate members, there is a concern that the increased number of parts will lead to a decrease in workability and an increase in costs. In response to these concerns, the joint device 1' configured as described above with reference to Figures 3 and 4 was devised. According to the joint device 1', the grip portion 21 is provided at the end of the anchor member 20, thereby increasing the anchoring force and making it possible to shorten the entire member. As shown in Figure 3, the longitudinal length L2 of the anchor member 20 in the joint device 1' is designed to be, for example, approximately 200 mm. In addition, the overall length of the members of the joint device 1' is designed to be, for example, approximately 300 mm.

However, by providing the grip portion 21, when a force is applied to pull the concrete out, stress is concentrated locally around the grip portion 21 (see the dashed line in Figure 3), which may cause cracks in the concrete around the grip portion 21, resulting in concerns that the connecting function may not be fully realized.

(Coupling device according to an embodiment of the present invention)
Therefore, the present inventors have conducted extensive research into a coupling device that can be integrally molded as a casting by suppressing the length of the component, and that ensures the anchoring force of the connecting component, and have devised a coupling device 30 according to an embodiment of the present invention described below (hereinafter, also referred to as coupling device 30). Figure 5 is a schematic explanatory diagram of a single component of the coupling device 30 according to an embodiment of the present invention, where (a) is a schematic plan view, and (b) is a schematic side view.

As shown in FIG. 5, the joint device 30 is composed of a connecting member 35 for connecting precast members (concrete members) to each other, and an anchor member 36 that protrudes from the connecting member 35 toward the precast members (concrete members) and is embedded inside the precast members so as to be fixed (anchored) to the precast members. The connecting member 35 and the anchor member 36 may be manufactured integrally as cast or forged members.

The shape of the connecting member 35 may be designed arbitrarily, but for example, when a pair of coupling devices 30 is used to form an insertion type coupling structure, it may be composed of a male member as the fitting body and a female member as the fitted body. Alternatively, when a pair of coupling devices 30 is used to form a so-called cotter type coupling structure, it may be composed of only a female member as the fitted body, and a cotter member, which is a separate member, may be used as the fitting body. Figure 5 illustrates a configuration using a C-shaped part as the fitted body (female member) as an example of the connecting member 35. Note that the configuration of the C-shaped part is the same as that of the conventional C-shaped part 10 shown in Figures 1 to 4, so a description will be omitted.

The anchor member 36 is a rod-shaped member having a conical shape that gradually expands in diameter from one end 38, which is the connecting portion with the connecting member 35, to the other end 39. The taper angle of the conical shape of the anchor member 36 can be designed arbitrarily, but it is preferable to design it so that the anchor member 36, which is fixed inside the precast member, can fully exert a reaction force against pulling out. The longitudinal length L3 of the anchor member 36 is configured to be shorter than the length L1 of the cylindrical member 11 described above.

Figure 6 is a schematic diagram of the pull-out resistance force F of the anchor member 36 according to this embodiment, and shows the relationship between the shape of the anchor member 36 (length L3, taper angle θ, radius r, R, etc.) and the concrete compressive stress (proof stress) fck. In Figure 6, the same reference numerals are used for the components shown in Figure 5, and their explanations are omitted.

As shown in Fig. 6, the cone angle (taper angle) of the anchor member 36 is θ, the radius (minimum diameter) of the anchor start point is r, the radius (maximum diameter) of the anchor end point is R, and a friction angle is δ. Consider the case where the anchor member 36 is embedded in concrete and an attempt is made to pull it out. The wedge force W shown in the figure satisfies the relationship of the following formula (1).
W=F/(sin(θ+δ))...(1)
Since the horizontal component Wh of the wedge force W becomes the bearing reaction force of the concrete, the relationship between the anchor length L3, the pull-out resistance force F, the cone angle θ, and the concrete compressive stress fck is expressed by the following equation (2).
L3=α・F・cot(θ+δ)/(π・fck・(r+R)) ...(2)
Here, α is a predetermined safety factor.

From the above formula (2), it can be seen that the pull-out resistance force F of the anchor member 36 according to this embodiment is proportional to the product of fck, tan(θ+δ), and the anchor surface area. In other words, it can be said that the concrete compressive stress fck contributes greatly to the pull-out resistance force F. This concrete compressive stress fck is, for example, 40 N/ ^mm2 for general precast concrete.
On the other hand, when the anchor member has a conventional cylindrical shape as described above with reference to Figures 1 and 2, the only resistance that can be expected is the product of the friction force between the member and the concrete (e.g., about 4 N/mm2) and the surface area of the anchor.
Therefore, it is understood that the pull-out resistance force F of the anchor member 36 according to this embodiment is an extremely large value compared to the conventional resistance force.

The following describes the configuration for constructing a joint structure 40 using a pair of joint devices 30 according to an embodiment of the present invention to connect adjacent precast members.

(First connection form of the coupling device)
First, as a first connection form, we will explain the case where adjacent precast members P1 and P2 are connected using a first coupling device 30a having a male member as a mating body and a second coupling device 30b having a female member as a mated body.

Figure 7 is a schematic diagram of the first connection form. The anchor member 36a of the first coupling device 30a is embedded inside the precast member P1. Here, the connecting member (male member) 35a of the first coupling device 30a is embedded in a state where it protrudes (exposed) from the precast member P1. Furthermore, the anchor member 36b of the second coupling device 30b is embedded inside the precast member P2. Here, the connecting member (female member) 35b of the second coupling device 30b is embedded inside the precast member P2.

As shown in FIG. 7, with the precast members P1 and P2 adjacent to each other, the connecting members 35a and 35b are butted together, and the connecting member (male member) 35a of the first coupling device 30a is fitted into the connecting member (female member) 35b of the second coupling device 30b. The connecting member 35b may be of any shape as long as it has a space inside into which the connecting member 35a can be fitted. If necessary, a time-hardening material such as mortar or a cover member (not shown) is applied to the joint portion, completing the connection between the precast members P1 and P2. The connecting member 35b may have the same configuration as the C-shaped part 10 described above.

(Second Connection Form of Joint Device)
Next, as a second connection form, we will explain the case where a so-called cotter-type joint structure is formed using a pair of joint devices 30, and adjacent precast members P1 and P2 are connected using a pair of joint devices 30 having the same configuration.

Figure 8 is a schematic diagram of the second connection form. In this connection form, a pair of joint devices 30c of the same configuration are used. An anchor member 36 of the joint device 30c is embedded inside the precast member P1. A similar anchor member 36 of the joint device 30c is also embedded inside the precast member P2. At this time, the connecting members 35 of each joint device 30c, 30c are exposed. The connecting member 35 here is a female member that serves as a mated body, and may have the same configuration as the C-shaped part 10 described above, for example.

As shown in Fig. 8, a pair of connecting members 35, 35 are butted together with precast members P1 and P2 adjacent to each other. A cotter member 50 having an H-shaped cross section as a fitting body is inserted into the fitting space S thus formed, and bolts 54 (54a, 54b) are inserted into bolt holes 53 (53a, 53b) formed in the cotter member 50 and engaged with the bottoms of the connecting members 35, 35 to connect them together. If necessary, a time-hardening material such as mortar or a cover member (not shown) is applied to the connecting portion, completing the connection between the precast members P1 and P2.
It should be noted that the shape and configuration of the cotter member 50 illustrated here are merely examples, and in the joint device 30c of this embodiment, the shape and configuration of the cotter member 50 are arbitrary as long as they suitably connect a pair of connecting members 35, 35.

When precast members P1 and P2 are connected using the configurations related to the first and second connection forms described above, a tensile force acts between adjacent precast members P1 and P2 to separate them, and even if a pull-out force is applied to anchor members 36a and 36b, sufficient anchoring force is ensured by the action of the bearing reaction force in addition to the adhesion force between anchor members 36a and 36b and the surrounding concrete. In addition, by making the anchor members 36a and 36b into a cone shape that gradually expands in diameter from one end 38 to the other end 39, there is no risk of localized stress concentration even if a pull-out force is applied.

(Action and Effect)
According to the joint device 30 of this embodiment and the joint structure 50 composed of a pair of joint devices 30a, 30b or 30c, 30c, whether the first or second connection form described above is adopted, a sufficient anchoring force is ensured between the cone-shaped anchor member 36 and the surrounding concrete by the action of the bearing reaction force in addition to the adhesion force between the cone-shaped anchor member 36 and the surrounding concrete. In particular, compared with the conventional cylindrical member 11, while only the adhesion force acts between the cylindrical member 11 and the surrounding concrete, the bearing reaction force acts between the cone-shaped anchor member 36 and the concrete in addition to the adhesion force. In other words, the pull-out force on the anchor member 36 is resolved into the adhesion force to the concrete and the bearing reaction force, and the pull-out resistance force (so-called anchoring force) is improved.

The bearing reaction force acts on the entire anchor member 36 in the same way as the adhesion force. Therefore, there is no risk of localized stress concentration in the anchor member 36, and the anchoring force can be ensured without lengthening the anchor member 36. For example, as described above with reference to FIG. 6, it is clear that the pull-out resistance F when the anchor member 36 according to the present invention is embedded in concrete and pulled out is significantly greater than in the past, and the anchoring force (pull-out resistance) is improved. This allows the overall length of the joint device 30 to be kept short, and it can be manufactured as a cast or forged member by integral molding, reducing the number of parts and costs.

Although one embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

For example, in the above embodiment, a joint structure is formed by fitting a male member and a female member as a joint device (see first connection form), and a joint structure is formed by using a pair of female members and a cotter member, which is a separate member, as the fitting body (see second connection form). However, the scope of application of the technology of the present invention is not limited to this. In other words, the joint device of the present invention only requires that the anchor member has a predetermined shape, and the other components can be designed as desired.

In the above embodiment, the anchor member is illustrated and described as being conical, but the present invention is not limited to this. That is, the shape of the anchor member in the present invention may be any shape as long as its cross section gradually expands in diameter, and the cross section may be rectangular or elliptical. Various segments and decks are considered as precast concrete members to which the joint device of the present invention is applied, and the cross section of these segments and decks is characterized by being narrow in the thickness direction and wide in the width direction. When applying the joint device to such precast concrete members, the cross section of the anchor member may also be rectangular or elliptical, which does not expand in the thickness direction but expands in the width direction. This is expected to have the effect of narrowing the remaining thickness of the concrete in the thickness direction and preventing cracks due to stress concentration.

The present invention is used to connect components used in constructing structures, and can be applied to joint devices and joint structures used to connect precast concrete components, for example.

Reference Signs List 1, 1'... (conventional) joint device 5... H-shaped member 10... C-shaped part 11... Cylindrical member 13... Bolt hole 14... Bolt 20... Anchor member (of conventional joint device) 21... Grip portion 30... (Joint device according to an embodiment of the present invention) 35... Connection member 36... Anchor member 40... Joint structure 41... Bolt hole 42... Bolt 50... Cotter member 53... Bolt hole 54... Bolt P1, P2... (pair of) precast members

Claims (2)

It is embedded in a pair of precast members and is used to connect the pair of precast members ,
a connecting member for connecting the pair of coupling devices in a state in which the coupling devices are butted against each other;
an anchor member fixed within the precast member to prevent the coupling device from being pulled out of the precast member;
The precast member is a segment or a deck slab;
The anchor member is a rod-shaped member having a shape that does not expand in the thickness direction of the segment or deck slab but gradually expands in diameter in the width direction from one end , which is a connecting portion with the connecting member, to the other end, and is a joint structure formed by connecting a pair of joint devices,
One of the coupling devices has a male member as the connecting member,
The other coupling device has a female member as the connecting member,
A joint structure characterized in that a pair of the precast members are connected together by fitting the male member into the female member. 2. The joint structure according to claim 1, wherein the connecting member and the anchor member are integrally formed cast or forged members.

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