JP7731538B2 - Precast member connection structure - Google Patents

Description

The present invention relates to a precast member connection structure used to connect members used in constructing a structure, for example, to connect precast concrete members.

In modern cities, when constructing structures such as buildings and various underground structures, a known technique is to transport pre-fabricated concrete components from factories to the construction site and then construct columns and beams by combining the components or assembling them with existing components. It is also known that tunnel construction is carried out by connecting multiple segments adjacent to each other in the circumferential direction.

A variety of connecting means are used to connect various components together. For example, Patent Document 1 discloses a technology that uses a joint as a segment connector by combining a mating member and a mated member. Furthermore, Patent Document 2, for example, discloses a cotter-type joint device for fastening segments and various concrete members. These connecting means not only maintain a strong connection, but also have the advantage of facilitating workability (removal).

Patent No. 4344551 Patent No. 3787576

As exemplified by the connector described in Patent Document 1, it is known to integrally mold the anchor member, fitting body, and fitted body into a casting. However, as the structure to be constructed increases in size, it becomes necessary to increase the overall length of the components, which can make it difficult to mold them into a single casting. Furthermore, when lengthening the connecting member, it is possible to integrate the anchor member and fitting body, which are manufactured as separate components, using screws or other fasteners, but this raises concerns about an increase in the number of components and rising costs.

Furthermore, in the joint device described in Patent Document 2, a grip portion (bearing portion) is formed at the tip of the anchor member to increase anchoring strength and avoid increasing the length of the anchor member. However, with a configuration in which a grip portion is formed on the anchor member in this way, 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 and other problems in the structure (concrete, etc.).

In light of the above, the object of the present invention is to provide a coupling device that can be molded as a single casting by minimizing the length of the component, while still ensuring the anchoring force of the connecting component.

In order to achieve the above-mentioned object, according to the present invention, there is provided a connection structure for precast members in which a pair of coupling devices are embedded in the precast members to connect the pair of coupling devices, the coupling devices having a connecting member for connecting the pair of coupling devices when the pair of coupling devices are butt-jointed, and an anchor member that is fixed inside the precast members to prevent the coupling device from being pulled out of the precast members, the precast members being segments or deck slabs, and the anchor member being a rod-shaped member that does not expand in the thickness direction of the segment or deck slab over the entire length of the anchor member but gradually expands in diameter in the width direction as it moves from one end, which is the connection part with the connecting member , to the other end.

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

In addition, according to the present invention, there is provided a connecting structure for precast members as described above, characterized in that a pair of coupling devices each have female members of the same configuration as the connecting members, and the pair of female members are butted together, a cotter member as a fitting body is inserted into the fitting space of the female members, and the cotter member is connected to the female members with a bolt , thereby connecting the pair of precast members .

The present invention provides a coupling device that can be molded as a single casting by minimizing the length of the component, while still ensuring the anchoring force of the connecting component.

FIG. 1 is a schematic explanatory diagram showing an example of a conventional joint device used to join precast members together. FIG. 10 is a schematic explanatory view of a single member of a conventional coupling device. FIG. 10 is a schematic explanatory diagram showing another form of a conventional joint device used to join precast members together. FIG. 10 is a schematic explanatory view of a single member of a conventional coupling device. 1 is a schematic explanatory view of a single member of a coupling device according to an embodiment of the present invention. FIG. 10 is a schematic explanatory diagram of the pull-out resistance force F of the anchor member according to the present embodiment. FIG. FIG. 10 is a schematic explanatory diagram of a first connection configuration. FIG. 10 is a schematic explanatory diagram of a second connection configuration.

Embodiments of the present invention will be described below with reference to the drawings. Note that in this specification and drawings, components having substantially the same functional configuration may be assigned 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 simply referred to as precast members).In addition, when constructing flat structures such as those used to pave large areas such as airport parking lots 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 referred to as joint device 1) used to join precast members, showing a pair of butt-jointed joint devices 1 (1a, 1b) constructed and joined using an H-shaped member 5. Figure 2 is a schematic diagram of each individual member of joint device 1, with (a) being a schematic plan view and (b) being a schematic side view. As shown in Figures 1 and 2, joint device 1 is composed of C-shaped parts 10 (10a, 10b) as mated members and cylindrical members 11 (11a, 11b) as anchor members. These C-shaped parts 10 and cylindrical members 11 are integrated by a connecting means such as a screw mechanism to form joint device 1.

As shown in Figure 1, when connecting adjacent precast members P1 and P2 using a pair of coupling devices 1a and 1b, the coupling devices 1a and 1b are embedded inside each precast member P1 and P2 with the C-shaped component 10 exposed. At this time, the cylindrical component 11 is embedded inside the precast members P1 and P2 so that it is fixed (anchored) in the concrete that constitutes them. Then, the H-shaped component 5 is inserted into the mating space S formed by butting together the pair of C-shaped components 10a and 10b, and bolts 14 (14a, 14b) are inserted into the bolt holes 13 (13a, 13b) formed in the H-shaped component 5 to engage with the bottom of the C-shaped component 10. Then, a time-hardening material such as mortar or a cover component (not shown) is applied to the joint portion, including the mating space S, as needed. 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 conventional joint device 1 (hereinafter referred to as joint device 1') used to join precast members. Figure 4 is a schematic explanatory diagram of a single member of joint device 1', with (a) being a schematic plan view and (b) being a schematic side view. In the joint device 1' shown in Figures 3 and 4, 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 will be 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 longitudinal end of the anchor member 20 and a grip portion 21 at the other end. Ribs 24 are provided on the surface of the anchor member 20. Here, the anchor member 20 is generally cylindrical, and the grip portion 21 has a generally disk shape with a larger diameter than the anchor member 20 and a predetermined thickness in the longitudinal direction of the member.

(Issues with conventional coupling devices)
In the conventional joint device 1 configured as described above with reference to Figures 1 and 2, the cylindrical member 11 must have a certain length in order to design the joint to take into account factors such as the reaction force (so-called anchor force) against pullout from the concrete, resulting in a long member. The anchor force due to adhesion to concrete is calculated as the product of the circumferential area and length of the anchor part (here, the cylindrical member 11). It is known that the adhesion force of concrete is small, less than one-tenth 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 a long anchor part is required.

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

In the coupling device 1, if the C-shaped part 10 and the cylindrical member 11 were manufactured as separate components, there would be concerns that the increased number of components would reduce workability and increase costs. In response to these concerns, the coupling device 1' configured as described above with reference to Figures 3 and 4 was devised. According to the coupling device 1', the provision of a grip portion 21 at the end of the anchor member 20 increases anchoring force and allows the entire member to be shortened. As shown in Figure 3, the longitudinal length L2 of the anchor member 20 in the coupling device 1' is designed to be, for example, approximately 200 mm. Furthermore, the overall length of the coupling device 1' members 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, potentially preventing the concrete from fully functioning as a connection.

(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 anchoring force as a connecting component, and have devised a coupling device 30 (hereinafter also referred to as coupling device 30) according to an embodiment of the present invention, which will be described below. 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 Figure 5, the joint device 30 is composed of a connecting member 35 for connecting precast members (concrete members) together, and an anchor member 36 that protrudes from the connecting member 35 toward the precast members (concrete members) and is embedded within the precast members so as to be fixed (anchored) to the precast members. The connecting member 35 and anchor member 36 may be manufactured integrally as cast or forged members.

The shape of the connecting member 35 can be designed arbitrarily. For example, when a pair of coupling devices 30 form an insertion-type coupling structure, it may be composed of a male member as the mating member and a female member as the mated member. Alternatively, when a pair of coupling devices 30 form a so-called cotter-type coupling structure, it may be composed of only a female member as the mated member, with a separate cotter member as the mating member. Figure 5 illustrates a configuration using a C-shaped component as the mated member (female component) as an example of a connecting member 35. Note that the configuration of the C-shaped component is similar to that of the conventional C-shaped component 10 shown in Figures 1 to 4, and therefore will not be described here.

The anchor member 36 is a rod-shaped member with a conical shape that gradually widens in diameter from one end 38, where it connects to 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, once fixed inside the precast member, exerts a sufficient reaction force against pull-out. The longitudinal length L3 of the anchor member 36 is also configured to be shorter than the length L1 of the cylindrical member 11 described above.

Figure 6 is a schematic diagram illustrating 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, radii r and R, etc.) and the concrete compressive stress (proof stress) fck. Note that in Figure 6, the same reference numerals are used for the components shown in Figure 5, and their description will be omitted.

As shown in Figure 6, let the cone angle (taper angle) of the anchor member 36 be θ, the radius (minimum diameter) of the anchor start point be r, and the radius (maximum diameter) of the anchor end point be R. Let us consider a case in which the anchor member 36 is embedded in concrete with a friction angle of δ, and an attempt is made to pull out the anchor member 36. The wedge force W shown in the figure satisfies the relationship of the following equation (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, pull-out resistance force F, cone angle θ, and 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 coefficient.

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, if the anchor member has a conventional cylindrical shape as described above with reference to Figures 1 and 2, the resistance that can be expected is only approximately the product of the friction force between the member and the concrete (for example, about 4 N/mm2) and the surface area of the anchor.
Therefore, it can be seen 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 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 the mating body and a second coupling device 30b having a female member as the mated body.

Figure 7 is a schematic diagram illustrating the first connection configuration. The anchor member 36a of the first coupling device 30a is embedded inside 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 precast member P2. Here, the connecting member (female member) 35b of the second coupling device 30b is embedded inside precast member P2.

As shown in Figure 7, with precast members P1 and P2 adjacent to each other, 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 that can fit the connecting member 35a. If necessary, a time-hardening material such as mortar or a cover member (not shown) is applied to the joint, completing the connection between 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 coupling device)
Next, as a second connection form, we will explain the case where a pair of joint devices 30 are used to form a so-called cotter-type joint structure, 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 illustrating the second connection configuration. In this connection configuration, a pair of identical coupling devices 30c are used. The anchor member 36 of the coupling device 30c is embedded inside precast member P1. A similar anchor member 36 of the coupling device 30c is also embedded inside precast member P2. At this time, the connecting members 35 of each coupling 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 Figure 8, a pair of connecting members 35, 35 are butted together while precast members P1 and P2 are adjacent to each other. A cotter member 50, which serves as a fitting body with an H-shaped cross section, 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 complete the connection. 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.
It should be noted that the shape and configuration of the cotter member 50 illustrated here are merely examples, and in the coupling device 30c according to this embodiment, the shape and configuration of the cotter member 50 are arbitrary as long as they suitably connect the 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, separating them. 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 adhesive force between anchor members 36a and 36b and the surrounding concrete. Furthermore, by giving anchor members 36a and 36b a conical shape that gradually widens 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)
With the joint device 30 according to this embodiment and the joint structure 40 formed by a pair of joint devices 30a, 30b or 30c, 30c, whether the first or second connection configuration described above is adopted, sufficient anchoring force is ensured between the conical anchor member 36 and the surrounding concrete by the action of the bearing reaction force in addition to the adhesion force between the conical anchor member 36 and the surrounding concrete. In particular, compared to the conventional cylindrical member 11, while only adhesion force acts between the cylindrical member 11 and the surrounding concrete, the bearing reaction force acts in addition to the adhesion force between the conical anchor member 36 and the concrete. In other words, the pull-out force on the anchor member 36 is resolved into the adhesion force with the concrete and the bearing reaction force, thereby improving the pull-out resistance (so-called anchoring force).

Furthermore, the bearing reaction force acts on the entire anchor member 36, just like the adhesion force. Therefore, there is no risk of localized stress concentration in the anchor member 36, and anchoring force can be ensured without increasing the length of the anchor member 36. For example, as described above with reference to Figure 6, it is clear that the pull-out resistance force F when the anchor member 36 of the present invention is embedded in concrete and pulled out is significantly greater than conventional anchor members, thereby improving anchoring force (pull-out resistance force). This allows the overall length of the coupling device 30 to be kept short and can be manufactured as a single cast or forged member, reducing the number of parts and costs.

The above describes one example of an embodiment of the present invention, but the present invention is not limited to the illustrated form. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the ideas set forth in the claims, and it is understood that these naturally fall within the technical scope of the present invention.

For example, in the above embodiments, we have described a case in which a male member and a female member are used as a coupling device and are fitted together to form a coupling structure (see first connection configuration), and a case in which the coupling device is made up of a pair of female members and a separate cotter member is used as the fitting body to form a coupling structure (see second connection configuration). However, the scope of application of the technology of the present invention is not limited to this. In other words, the coupling device of the present invention only requires that the anchor member have a predetermined shape, and the other components can be designed as desired.

In addition, while the above embodiment illustrates and describes a conical anchor member, 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. Precast concrete components to which the joint device of the present invention can be applied include various segments and deck slabs, and the cross section of these segments and deck slabs is characterized by being narrow in the thickness direction and wide in the width direction. When applying a joint device to such precast concrete components, the cross section of the anchor member may also be rectangular or elliptical, expanding in the width direction rather than in the thickness direction. This is expected to have the effects of narrowing the remaining concrete thickness in the thickness direction and preventing cracks due to stress concentration.

The present invention is used to connect members used in constructing a structure, and can be applied to a precast member connection structure used to connect precast concrete members, for example.

DESCRIPTION OF SYMBOLS 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... Connecting 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 (3)

A connection structure in which a pair of precast members are connected to each other by a pair of joint devices embedded in the precast members,
The coupling device includes a coupling member for coupling the pair of coupling devices together when the coupling devices are butted against each other;
an anchor member fixed to the interior of 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;
A connecting structure for precast members, characterized in that 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 as it moves from one end, which is the connecting part with the connecting member, to the other end, over the entire length of the anchor member . 2. The precast member connection structure according to claim 1, wherein the connecting member and the anchor member are integrally formed cast or forged members. The precast member connection structure according to claim 1 or 2,
Each of the pair of coupling devices has a female member having the same configuration as the connecting member,
A connecting structure for precast members, characterized in that a pair of female members are butted together, a cotter member as a fitting body is inserted into the fitting space of the female members, and the cotter member is connected to the female members with a bolt, thereby connecting the pair of precast members to each other.