Intermediate anchoring device for new or existing prestressing steel members and intermediate anchoring method using the same

Abstract

To provide an intermediate anchorage assembly suitably used for PC steel in a strained state and excellent in workability with a small number of parts.SOLUTION: An intermediate anchorage assembly 30 comprises a sleeve 100 separated detachably on PC steel B in a strained state and a wedge 140, wherein the sleeve 100 is separated into a sleeve piece 110 of an inner cylindrical side in a hollow cylindrical shape with a taper combined with a taper of the wedge 140 and a sleeve piece 120 of an outer cylindrical side in a hollow cylindrical shape which is arranged outside of the sleeve piece 110 of the inner cylindrical side so as to function as a sleeve by integrally assembling the sleeve 100 with the wedge 140 through connection of the sleeve piece 110 and the sleeve piece 120.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an intermediate fixing device that is suitable for use with newly installed or existing prestressed concrete steel members in a tensioned state, and an intermediate fixing construction method using the same. In this invention, the terms "wedge," "crest," "button," "crest" and "wedge" may be used, but they all have the same structure. Furthermore, the prestressing steel members in the newly installed or existing prestressing steel members (sometimes referred to as prestressing steel members) covered by this invention include prestressing steel wires, prestressing steel rods, prestressing steel strands (PC steel strands), and prestressing steel members whose outer surfaces are coated with a resin (such as epoxy). [Background technology]

[0002] Some concrete structures are prestressed by the tension of embedded tendons. Such concrete structures may require partial removal for repair, reinforcement, or renovation. For example, a portion of a bridge girder may be removed across its width, and the remaining portion may be replaced with a new girder while maintaining traffic. Also, when a portion of a bridge girder's axial direction, such as the girder end, deteriorates and requires repair, the girder end may be removed and new concrete poured to repair it. In addition, part of the building may be demolished.

[0003] In such cases, if a continuous tendon is placed across the portion of the concrete structure to be removed and the remaining portion, and prestress is introduced, the middle portion of the tendon is exposed and an intermediate anchor is attached to fix it to the concrete in the remaining portion.The tendon is then maintained in a tensioned state in the remaining portion of the concrete structure, and the tendon in the portion to be removed is cut and the concrete structure is removed.

[0004] For example, Japanese Patent Application Laid-Open No. 2018-017029 (Patent Document 1) discloses an intermediate fixing structure that fixes the tension material in the intermediate portion while tensioning force is being applied to it. The intermediate anchoring structure disclosed in Patent Document 1 is characterized in that an anchoring block is formed by joining a pair of separable half blocks, a tensioning material is inserted into a hollow hole formed between the pair of half blocks, the anchoring block and the tensioning material are joined by a filler material that is filled between the tensioning material and the inner surface of the hollow hole and hardens, the anchoring block is anchored to the structure so as to transmit the tension force of the tensioning material, and multiple protrusions are formed on the outer surface of the part of the tensioning material inserted into the hollow hole, made of metal adhered by metal spraying. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-017029 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although it is possible to form a sleeve in the hollow hole in the intermediate fixing structure disclosed in the above-mentioned Patent Document 1 and combine this sleeve with a corresponding wedge to create an intermediate fixing device (an intermediate fixing device having a configuration in which the half sleeve is bolted together using a half sleeve and a half wedge), such an intermediate fixing device has a large number of parts, which makes it heavy and results in poor workability.

[0007] The present invention has been developed in consideration of the above-mentioned problems of the prior art, and its object is to provide an intermediate tensioner with excellent workability that can be suitably used for newly installed or existing prestressed concrete strands. To provide a fixing tool and an intermediate fixing method using the same. [Means for solving the problem]

[0008] In order to achieve the above object, the intermediate anchoring device for newly installed or existing PC steel members and the intermediate anchoring method using the same according to the present invention employ the following technical means. In other words, an intermediate fixing device for newly installed or existing PC steel strands according to one aspect of the present invention is an intermediate fixing device that is suitable for use with tensioned PC steel strands in the middle of a newly installed or existing concrete structure, and includes a wedge that is divided into two or more wedge pieces when viewed from a plane perpendicular to the longitudinal direction of the PC steel strand, and a sleeve that is divided into an inner tube side sleeve piece with a taper that can be combined with the wedge, and an outer tube side sleeve piece that is provided on the outside of the inner tube side sleeve piece, and is characterized in that with respect to the inner tube side sleeve piece and the outer tube side sleeve piece, at least the inner tube side sleeve piece has a notch portion into which the PC steel strand can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel strand, and the inner tube side sleeve piece and the outer tube side sleeve piece are joined together to form a sleeve that functions as a sleeve that can be combined with the wedge. The outer tube sleeve piece may be a sheet made of, for example, FRP (Fiber Reinforced Plastics), and the inner tube sleeve piece and the outer tube sleeve piece may be integrated as a sleeve by wrapping the sheet-like outer tube sleeve piece around the outer periphery of the inner tube sleeve piece. In this case, the notch in the sheet-like outer tube sleeve piece is not an essential component.

[0009] Preferably, a key is provided across the key groove provided on the outer peripheral surface of the sleeve piece on the inner tube side and the key groove provided on the inner peripheral surface of the sleeve piece on the outer tube side, and the sleeve piece on the inner tube side and the sleeve piece on the outer tube side are joined together to form an integrated sleeve. More preferably, the male thread provided on the outer peripheral surface of the sleeve piece on the inner tube side and the female thread provided on the inner peripheral surface of the sleeve piece on the outer tube side are screwed together, and the sleeve piece on the inner tube side and the sleeve piece on the outer tube side are joined together to form an integrated sleeve.

[0010] In addition, an intermediate fixing device for newly installed or existing PC steel members relating to another aspect of the present invention is an intermediate fixing device that is suitably used for PC steel members in a tensioned state in the middle of a newly installed or existing concrete structure, and includes a wedge divided into two or more wedge pieces when viewed from a plane perpendicular to the longitudinal direction of the PC steel member, and a sleeve having a taper that can be combined with the wedge and a slit portion through which the PC steel member can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel member, and is characterized in that the opposing wall surfaces in the slit portion are connected using a connecting member, thereby regulating the spacing of the slit portion when viewed from the perpendicular plane, and functioning as a sleeve that can be combined with the wedge.

[0011] Preferably, the connecting member includes a female threaded hole provided in at least one of the opposing wall surfaces and a male screw passed through a hole provided in the other wall surface, and the male screw is screwed into the female threaded hole to connect the wall surfaces, thereby regulating the spacing of the slit portions as viewed from the vertical plane. More preferably, the sleeve further includes a flat plate joined to the end face of the sleeve in the direction in which the taper widens and which is perpendicular to the longitudinal direction of the PC steel, the plate having a notch into which the PC steel can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel and through which a wedge protrusion provided at the end of the wedge in the direction in which the taper widens can protrude, and the plate can be configured so that by joining the plate to the end face of the sleeve, the wedge is positioned at a predetermined position on the sleeve and the wedge protrusion protrudes from the notch in the plate.

[0012] More preferably, the wire clip further includes a three-dimensional wire clip, the wire clip having at least a straight portion in the sleeve corresponding to the longitudinal length of the PC steel, an arc portion that is fitted into a wedge groove provided on the outer periphery of the end of the wedge in the direction in which the taper widens, on the side of the sleeve where the taper widens relative to the straight portion, and an insertion piece that is fitted into a sleeve hole provided on the end face of the sleeve in the direction in which the taper narrows, perpendicular to the longitudinal direction of the PC steel, on the side of the sleeve where the taper narrows relative to the straight portion.The arc portion of the wire clip is fitted into the wedge groove and the insertion piece of the wire clip is fitted into the sleeve hole, so that the wedge is positioned at a predetermined position in the sleeve and the straight portion of the wire clip is arranged along the outer periphery of the sleeve.

[0013] Furthermore, according to yet another aspect of the present invention, there is provided an intermediate anchoring method for new or existing prestressing tendons, which uses an intermediate anchor suitable for use with tensioned prestressing tendons in an intermediate portion of a new or existing concrete structure, and which includes: The method of fixing the prestressing tendons using an intermediate fixing device including a wedge divided into two or more wedge pieces when viewed from a plane perpendicular to the longitudinal direction of the prestressing tendon, and a sleeve having a taper that can be combined with the wedge and a structure that can be attached to the prestressing tendon in a tensioned state, includes a step of chipping the concrete to expose the prestressing tendon in a tensioned state when the prestressing tendon fixed by the intermediate fixing device is embedded in concrete, and a step of attaching the two or more divided wedge pieces to the prestressing tendon in a tensioned state so that the direction in which the taper of the wedge narrows is the direction in which the concrete is subjected to compressive force. a sleeve mounting step of mounting a sleeve having a structure that can be mounted on the prestressing steel member to the tensioned prestressing steel member so that the direction in which the taper of the sleeve narrows is the direction in which the compressive force is introduced into the concrete; a sleeve functioning step of making the sleeve function as a sleeve that can be combined with the wedge; and an insertion step of inserting two or more wedge pieces that have been mounted on the tensioned prestressing steel member in the divided state into the sleeve that has been made to function as a sleeve, with the taper direction of the wedge and the taper direction of the sleeve aligned.

[0014] Preferably, the inserting step can be configured to insert the wedge into the sleeve manually by an operator without using a jack. [Effects of the Invention]

[0015] The intermediate fixing device for newly installed or existing PC steel members and the intermediate fixing method using the same of the present invention make it possible to provide an intermediate fixing device with excellent workability that is suitable for use with newly installed or existing PC steel members in a tensioned state, and an intermediate fixing method using the same. [Brief explanation of the drawings]

[0016] [Figure 1]This is a diagram for explaining the application (division of work areas) of an intermediate fixing device (intermediate fixing device 30) of an embodiment of the present invention to a newly constructed concrete structure (prestressed concrete member) in which use is expected. [Figure 2] 1 is a diagram for explaining the application (repair) of an intermediate fixing device (intermediate fixing device 30) according to an embodiment of the present invention to an existing concrete structure (prestressed concrete member) in which use is expected. [Figure 3] 2A to 2C are diagrams for explaining a usage mode of an intermediate fixing tool (intermediate fixing tool 30) according to an embodiment of the present invention. [Figure 4] 1A is a plan view of a sleeve 100 (corresponding to sleeve S) and FIG. 1B is a plan view of a wedge 140 (corresponding to wedge W) that constitute the intermediate fixing tool 30. [Figure 5] 5A is a plan view showing the state in which sleeve 100 (corresponding to sleeve S) in FIG. 4 functions as a sleeve that can be combined with wedge 140 (corresponding to wedge W), and FIG. 5B is a diagram for explaining the function of the shear key. [Figure 6] 5 is a diagram for explaining a procedure for attaching intermediate fixing tool 30 using sleeve 100 (corresponding to sleeve S) and wedge 140 (corresponding to wedge W) in FIG. 4 to a PC steel member. [Figure 7] 10A is a plan view of a sleeve 200 (corresponding to sleeve S) (different from sleeve 100) and (B) a wedge 240 (corresponding to wedge W) (different from wedge 140) that constitute the intermediate fixing device 30. FIG. [Figure 8] 8 is a diagram for explaining a procedure for attaching intermediate fixing tool 30 using sleeve 200 (corresponding to sleeve S) and wedge 240 (corresponding to wedge W) in FIG. 7 to a PC steel member. [Figure 9] This is a plan view showing the state in which sleeve S10, sleeve S11 or sleeve S20 (corresponding to sleeve S) that constitutes intermediate fixing device 30 (separate from sleeve 100 and sleeve 200) functions as a sleeve that can be combined with wedge W (same as wedge 140). [Figure 10]10A and 10B are diagrams showing test results in which a test specimen was used to evaluate an intermediate fixing device 30 according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram illustrating an intermediate fixing device according to a first modified example of the embodiment of the present invention. [Figure 12] FIG. 10 is a view illustrating an intermediate fixing device according to a second modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Below, we will explain in detail an intermediate fixing device that is suitable for use with tensioned PC steel members that are applying compressive force to newly constructed or existing prestressed concrete members, and an intermediate fixing construction method that is suitable for use with newly constructed or existing prestressed concrete members using this intermediate fixing device, according to an embodiment of the present invention. In the drawings referred to in the following explanation, in order to facilitate understanding of the present invention, in some cases parts that should be represented by their external form rather than their internal form are represented as if they were seen through to the internal form, in some cases parts that should be represented by their cross section rather than their external form are represented by their external form, in some cases parts that should be represented by their external form rather than their cross section are represented by their cross section, in some cases cross sections are not hatched, in some cases parts that are not cross sections are hatched, in some cases detailed structures are omitted, and in some cases drawings of the same components do not match due to the omission of detailed structures.

[0018] <Structures where intermediate anchors are expected to be used> First, referring to Figure 1, we will explain an example of a newly constructed concrete structure (PC structure, prestressed concrete member, concrete body) in which the intermediate fixing device (intermediate fixing device 30) of an embodiment of the present invention is expected to be used. In new concrete structures, the construction section may be divided due to restrictions on the amount of concrete that can be poured at one time. In this case, the length of the prestressing tendons (PC steel bars) for the later construction section is prepared, but they may be temporarily stored in coil form due to storage space restrictions, etc. In this case, the anchoring device cannot be inserted from the end (the end of the coil). In such cases, it is envisioned that the intermediate anchoring device of the present invention, as shown in Figure 1, can be used as a method of introducing prestress into the concrete structure in the earlier construction section.

[0019] Next, referring to Figure 2, we will explain an example of an existing concrete structure (PC structure, prestressed concrete member, concrete body) in which the intermediate fixing device (intermediate fixing device 30) of an embodiment of the present invention is expected to be used. Existing concrete structures may require repairs due to deterioration over time, etc., and when such repairs are carried out, openings are often made (by chipping away at the concrete to expose the prestressing tendons) to fasten the existing prestressing tendons. In this case, since both ends of the tendons (existing prestressing tendons) are embedded in the concrete, anchors cannot be inserted from the ends. In such cases, the use of intermediate anchors according to the present invention, as shown in Figure 2, is envisioned as a method of introducing prestress.

[0020] Figure 3 shows an example of how the intermediate anchor (intermediate anchor 30) of the present invention is used in a new or existing concrete structure (PC structure, prestressed concrete member, concrete body). The intermediate anchor is attached to the existing prestressing tendon, which is in a tensioned state, to tension the existing prestressing tendon. We will now explain in detail the wedge W, which clamps the new or existing PC steel B on its inner surface and has a tapered outer surface, and the sleeve S, which has an inner surface that follows the tapered surface of the wedge W, that constitute the intermediate fixing device (intermediate fixing device 30) used in the construction method shown in Figures 1 to 3.

[0021] Furthermore, the materials used for these sleeves S and wedges W are not particularly limited and may include metals, resins, chemical fibers, etc., but in the following description they will be described as being the type of metal normally used as fixing devices for PC steel. In the intermediate fixing device according to the present embodiment, the sleeve S is roughly classified into two types (the inner-cylinder / outer-cylinder type shown in FIGS. 4 to 8 and the slit wall surface connecting type shown in FIG. 9), and there are two types of wedges W (the wedges W differ only in the number of divisions, while the sleeves S have a significantly different structure). 4 to 6, a sleeve 100 (inner cylinder outer cylinder type shear key joint type) will be described as the sleeve S, and a wedge 140 (three-part) will be described as the wedge W. 7 and 8, a sleeve 200 (an inner-cylinder, outer-cylinder type screw-fit type) will be described as the sleeve S, and a wedge 240 (split into two parts) will be described as the wedge W. 9, sleeves S10 and S20 (slit wall surface connection type) will be described as sleeves S (the wedge W in FIG. 9 is the same as the wedge 240 (divided into three)).

[0022] Furthermore, two modified examples that can be commonly used for these will be described with reference to FIGS. The following intermediate fixing devices are known that can be used as the intermediate fixing device according to the present invention. The prior art, described in the aforementioned Patent Document 1 (JP 2018-017029 A), is a fixing device attached to the intermediate portion of a tendon (PC steel member including a PC steel bar) whose ends have already been tensioned and which fixes the tendon to a surrounding structure while maintaining the tensioned state of the tendon. More specifically, the prior art described in the aforementioned Patent Document 1 (JP 2018-017029 A) is a fixing device in which a pair of separable half blocks are joined together to form a fixing block, a tensioned tendon is inserted into a hollow hole formed between the pair of half blocks, and the pair of half blocks are then joined together with multiple rows of bolts aligned in the axial direction of the tendon. An intermediate fixing device in which a sleeve is formed in this hollow hole and combined with a wedge corresponding to this sleeve (the configuration in which a wedge is combined with a sleeve in the intermediate fixing device described in JP 2018-017029 A is a configuration in which the half sleeve is bolted together using a half sleeve and a half wedge, and this configuration is approximately equivalent to the intermediate fixing device described in JP 57-084220 A filed by one of the applicants of the present application) may be described as prior art or comparative example in the following explanation.

[0023] <1: Inner and outer cylinder type: Shear key joint type> First, the sleeve 100 and the wedge 140 will be described. Figure 4(A) shows a plan view of the sleeve 100 that constitutes the intermediate fixing device 30, Figure 4(B) shows a plan view of the wedge 140, Figure 5(A) shows a plan view of the sleeve 100 (corresponding to sleeve S) shown in Figure 4 functioning as a sleeve that can be combined with wedge 140 (corresponding to wedge W), Figure 5(B) shows a diagram explaining the function of the shear key when functioning as a sleeve, and Figure 6 shows a diagram explaining the procedure for attaching the intermediate fixing device 30 to new or existing PC steel B exposed from a PC structure using the sleeve 100 and wedge 140 so that the sleeve 100 (corresponding to sleeve S) functions as a sleeve that can be combined with wedge 140 (corresponding to wedge W).

[0024] This intermediate fixing device 30 is composed of a sleeve 100 shown in Fig. 4(A) and a wedge 140 shown in Fig. 4(B) that is combined with the sleeve 100. Note that the side view (partial cross-sectional view) on the left side of Fig. 4(A) is a view seen from the direction of arrow X shown in the front view on the right side, and the side view on the left side and the front view on the right side of Fig. 4(B) are views of the wedge 140 formed by combining three divided wedge pieces. Here, the front view is a view seen from a plane perpendicular to the longitudinal direction of the new or existing prestressing steel B, and the side view is a view seen from a plane parallel to the longitudinal direction of the new or existing prestressing steel B (the same applies hereinafter).

[0025] As shown in Figure 4(B), the wedge 140 is divided into two or more wedge pieces (here, it is divided into three pieces, that is, wedge piece 142, wedge piece 144, and wedge piece 146) when viewed from a plane perpendicular to the longitudinal direction of the new or existing prestressing steel member B. Because it is divided in this way, it can be attached to the new or existing prestressing steel member B. Furthermore, the wedge 140 has a taper 140T by combining the three wedge pieces.

[0026] 4(A), the sleeve 100 is divided into a hollow cylindrical inner sleeve piece 110 having a taper 100T that can be combined with the taper 140T of the wedge 140, and a hollow cylindrical outer sleeve piece 120 that is joined to the inner sleeve piece 110 by a shear key K. An outer surface 116 of the inner sleeve piece 110 is provided with a key groove 118 that houses the shear key K, and an inner surface 126 of the outer sleeve piece 120 is provided with a key groove 128 that houses the shear key K. In addition, in order to prevent the shear key K from moving from the key groove in the longitudinal direction of the PC steel B, it is also preferable to, for example, provide a hole in the bottom of the key groove 118 of the sleeve piece 110 on the inner tube side to engage a protrusion provided on the shear key (furthermore, a female threaded hole is cut in the bottom of the groove and a female threaded hole that passes through the shear key K is cut, and the female threaded hole of the shear key K is screwed into the female threaded hole at the bottom of the groove using a fully threaded bolt (a bolt with a male thread cut along its entire length and a hexagonal socket on its end face, also known as a set screw)) (shown by a dotted line on the shear key K). The sleeve piece 110 on the inner tube side and the sleeve piece 120 on the outer tube side have cutout portions (cutout portion 114 formed by cutting out a portion of the main body 112 in the sleeve piece 110 on the inner tube side and cutout portion 124 formed by cutting out a portion of the main body 122 in the sleeve piece 120 on the outer tube side) into which the new or existing PC steel B can be inserted when viewed from a plane perpendicular to the longitudinal direction of the new or existing PC steel B.

[0027] Furthermore, the sleeve piece 110 on the inner tube side and the sleeve piece 120 on the outer tube side have shear keys K embedded in their respective key grooves 118 (sleeve piece 110 on the inner tube side) and key grooves 128 (sleeve piece 120 on the outer tube side), and by joining the sleeve piece 110 and the sleeve piece 120 together, they are integrated into the sleeve 100 and function as a sleeve that can be combined with the wedge 140.

[0028] More specifically, the sleeve piece 110 has a main body having a taper 100T at the center through which the new or existing prestressing steel member B is inserted (corresponding to the new or existing prestressing steel member B to be inserted). 112, and a part of the main body 112 is made into a notch portion 114, so the taper 100T does not exist over the entire circumference, and the taper 100T does not exist only at the part of the notch portion 114, but this does not affect the function of this intermediate fixing tool 30.

[0029] The function of the shear key K will now be described with reference to Fig. 5. Fig. 5(A) shows a side view (left side) and a front view (right side) of the intermediate fixing device 30, which is composed of the sleeve 100 and the wedge 140 (more specifically, the shear key K) in a state in which the sleeve piece 110 and the sleeve piece 120 are joined together to form the integrated sleeve 100, which functions as a sleeve to be combined with the wedge 140. In the intermediate fixing device 30 shown in Figure 5(A) which is composed of a sleeve 100 (more specifically, the sleeve piece 110 on the inner tube side and the sleeve piece 120 on the outer tube side) and a wedge 140 (more specifically, a shear key K), when the wedge 140 clamps the newly installed or existing PC steel B and tension is applied to the newly installed or existing PC steel B, the wedge 140 bites into the sleeve piece 110 on the inner tube side due to a wedge effect (indicated by the black arrow in Figure 5(B)), causing the cutout portion 114 to expand (the cutout width of the cutout portion 114 to widen) (indicated by the curved arrow in Figure 5(B)). At this time, because the inner sleeve piece 110 and the outer sleeve piece 120 are joined via the shear key K (contained within each other's key grooves 118 and 128), the deformation of the inner sleeve piece 110 (expansion of the notch 114) is transmitted to the outer sleeve piece 120 via the shear key K due to the engagement of the shear key K, and the deformation of the inner sleeve piece 110 (expansion of the notch 114) is borne by the outer sleeve piece 120. As a result, the deformation of the inner sleeve piece 110 is suppressed, the desired wedge effect is achieved, and the desired tension can be applied to the new or existing prestressing steel strand B.

[0030] The intermediate anchor 30 having such a structure is attached to a new or existing prestressing steel member B as follows: If the prestressing steel member B to be fixed by the intermediate anchor is embedded in concrete, an exposure step of chipping the concrete to expose the tensioned prestressing steel member B is required before the wedge attachment step described below. As shown in Figure 6(A), two or more divided wedge pieces (here, it is divided into three, so there are three wedge pieces 142, wedge piece 144 and wedge piece 146) are attached to the exposed new or existing PC steel B as a wedge attachment step so that the narrowing direction of the taper 140T of the wedge 140 is toward the surface (here, the direction shown in the side view of Figure 3) (see the black arrow on the wedge side).

[0031] In the sleeve installation step, the divided sleeve pieces (here, because it is divided into two, two inner-cylinder-side sleeve pieces 110 and an outer-cylinder-side sleeve piece 120) are installed on the exposed new or existing prestressing steel B so that the narrowing direction of the taper 100T of the sleeve 100 is toward the surface (here, the direction shown in the side view of FIG. 3) (see the black arrows on the sleeve side). More specifically, the two inner-cylinder-side sleeve pieces 110 and the outer-cylinder-side sleeve piece 120 are installed by approaching them to the new or existing prestressing steel B from the left and right directions in FIG. 6(A).

[0032] Next, as shown in FIG. 6(B), in order to integrate the divided sleeve pieces (here, since the sleeve pieces are divided into two, two inner-cylinder-side sleeve pieces 110 and an outer-cylinder-side sleeve piece 120) into a sleeve 100 and function as a sleeve to be combined with a wedge 140 (for the sleeve functioning step), the inner-cylinder-side sleeve piece 110 and the outer-cylinder-side sleeve piece 120 are aligned in the longitudinal direction of the new or existing PC steel B so that the shear key K accommodated in the key groove 118 provided on the outer circumferential surface 116 of the inner-cylinder-side sleeve piece 110 is accommodated in the key groove 128 provided on the inner circumferential surface 126 of the outer-cylinder-side sleeve piece 120 (conversely, the shear key K accommodated in the key groove 128 provided on the inner circumferential surface 126 of the outer-cylinder-side sleeve piece 120 may be accommodated in the key groove 118 provided on the outer circumferential surface 116 of the inner-cylinder-side sleeve piece 110). The inner sleeve piece 110 and the outer sleeve piece 120 are brought closer together (by sliding either one or both in the longitudinal direction of the new or existing PC steel B) to join the inner sleeve piece 110 and the outer sleeve piece 120. This allows the divided sleeve pieces (here divided into two, so the two inner sleeve pieces 110 and the outer sleeve piece 120) to be integrated as a sleeve and function as the sleeve 100 that can be combined with the wedge 140.

[0033] Finally, in an insertion step, two or more divided wedge pieces (in this case, three wedge pieces 142, 144, and 146, since the wedge is divided into three pieces) attached to the exposed new or existing PC steel B are inserted into sleeve 100 by aligning the direction of taper 140T of wedge 140 with the direction of taper 100T of sleeve 100, so that the pieces are integrated and can function as a sleeve that can be combined with wedge 140. In this way, the intermediate fixing device 30 is attached to the new or existing PC steel member B.

[0034] <2: Inner and outer cylinder type: screw-on type> Next, the sleeve 200 and the wedge 240 will be described. Figure 7(A) shows a plan view of the sleeve 200 that constitutes the intermediate fixing device 30, Figure 7(B) shows a plan view of the wedge 240, and Figure 8 shows a diagram illustrating the procedure for attaching the intermediate fixing device 30 to new or existing PC steel B exposed from a PC structure, using the sleeve 200 and wedge 240 so that the sleeve 200 (corresponding to sleeve S) functions as a sleeve that can be combined with the wedge 240 (corresponding to wedge W).

[0035] This intermediate fixing device 30 is composed of a sleeve 200 shown in Fig. 7(A) and a wedge 240 shown in Fig. 7(B) that is combined with the sleeve 200. Note that the side view (partial cross-sectional view) on the left side of Fig. 7(A) is a view seen from the direction of arrow X shown in the front view on the right side, and the side view on the left side and the front view on the right side of Fig. 7(B) are views of the wedge 240 formed by combining two divided wedge pieces.

[0036] As shown in Figure 7(B), the wedge 240 is divided into two or more wedge pieces (here, two wedge pieces 242 and 244 because it is divided into two) when viewed from a plane perpendicular to the longitudinal direction of the new or existing prestressing steel B. Because it is divided in this way, it can be attached to new or existing prestressing steel B. Furthermore, the wedge 240 has a taper 240T by combining the two wedge pieces.

[0037] 7(A), the sleeve 200 is divided into an inner-cylinder-side sleeve piece 210 having an outer thread (male thread) 216 and a taper 200T that mates with the taper 240T of the wedge 240, and an outer-cylinder-side sleeve piece 220 having an inner thread (female thread) 226 that screws into the outer thread (male thread) 216 of the inner-cylinder-side sleeve piece 210. The inner-cylinder-side sleeve piece 210 and the outer-cylinder-side sleeve piece 220 have cutouts (cutout 214 obtained by cutting out a part of the main body 212 of the inner-cylinder-side sleeve piece 210 and cutout 224 obtained by cutting out a part of the main body 222 of the outer-cylinder-side sleeve piece 220) into which the new or existing prestressing steel B can be inserted, as viewed from a plane perpendicular to the longitudinal direction of the new or existing prestressing steel B. It should be noted that the notch 224 into which the new or existing prestressing steel B can be inserted does not necessarily have to be provided as long as the structure allows the inner tube side sleeve piece 210 and the outer tube side sleeve piece 220 to be joined. For example, the outer tube side sleeve piece 220 may be a sheet made of FRP, and the inner tube side sleeve piece 210 and the outer tube side sleeve piece 220 may be integrated as a sleeve by wrapping the sheet-like outer tube side sleeve piece 220 around the outer periphery of the inner tube side sleeve piece 210, and function as a sleeve that can be combined with the wedge 240. In this case, the sheet-like outer tube side sleeve The notch 224 of the piece 220 is not an essential component. Furthermore, the sleeve piece 210 on the inner cylinder side and the sleeve piece 220 on the outer cylinder side are integrated as the sleeve 200 by threading the outer thread (male thread) 216 and the inner thread (female thread) 226 together, and function as a sleeve that can be combined with the wedge 240.

[0038] More specifically, the sleeve piece 210 has a main body 212 with a taper 200T (corresponding to the new or existing PC steel B to be inserted) in the center, through which the new or existing PC steel B is inserted, and since a portion of the main body 212 is made into a cutout portion 214, the taper 200T does not exist around the entire circumference; only the portion of the cutout portion 214 does not have the taper 200T, but this does not affect the function of this intermediate fixing device 30.

[0039] The intermediate anchor 30 having such a structure is attached to a new or existing prestressing steel member B as follows. As described above, if the prestressing steel member B to be fixed by the intermediate anchor is embedded in concrete, an exposure step of chipping the concrete to expose the tensioned prestressing steel member B is required before the wedge attachment step described below. As shown in Figure 8(A), two or more divided wedge pieces (here, two wedge pieces 242 and 244 because the wedge is divided into two) are attached to the exposed new or existing PC steel B as a wedge attachment step so that the narrowing direction of the taper 240T of the wedge 240 is toward the surface (here, the direction shown in the side view of Figure 3) (see the black arrow on the wedge side).

[0040] In the sleeve installation step, the divided sleeve pieces (here, because it is divided into two, two inner-cylinder-side sleeve pieces 210 and an outer-cylinder-side sleeve piece 220) are installed on the exposed new or existing prestressing steel B so that the narrowing direction of the taper 200T of the sleeve 200 is toward the surface (here, the direction shown in the side view of FIG. 3) (see the black arrow on the sleeve side). More specifically, the two inner-cylinder-side sleeve pieces 210 and the outer-cylinder-side sleeve piece 220 are installed by approaching them to the new or existing prestressing steel B from the left and right directions in FIG. 8(A).

[0041] 8(B), the divided sleeve pieces (here, because it is divided into two, two inner-cylinder-side sleeve pieces 210 and an outer-cylinder-side sleeve piece 220) are integrated as sleeve 200 to function as a sleeve that can be combined with wedge 240 (for the sleeve functioning step), and outer threads (male threads) 216 of inner-cylinder-side sleeve piece 210 and inner threads (female threads) 226 of outer-cylinder-side sleeve piece 220 are threaded together. This allows the divided sleeve pieces (here, because it is divided into two, two inner-cylinder-side sleeve pieces 210 and an outer-cylinder-side sleeve piece 220) to be integrated as sleeves and function as sleeve 200 that can be combined with wedge 240.

[0042] Finally, in an insertion step, two or more divided wedge pieces (in this case, two wedge pieces 242 and 244 because the wedge is divided into two pieces) attached to the exposed new or existing PC steel B are inserted into sleeve 200 by aligning the direction of taper 240T of wedge 240 with the direction of taper 200T of sleeve 200, so that the pieces are integrated and can function as a sleeve that can be combined with wedge 140. In this way, the intermediate fixing device 30 is attached to the new or existing PC steel member B.

[0043] <3: Slit wall connection type> Both the intermediate fixing device 30 composed of the sleeve 100 and the wedge 140 and the intermediate fixing device 30 composed of the sleeve 200 and the wedge 240 described above are of the inner-outer cylinder type. Next, intermediate fixing devices 30 including the slit wall surface connecting type sleeves S10, S11, and S20 will be described in detail below with reference to FIG. The wedge W shown in FIG. 9, which is combined with the sleeves S10, S11 and S20, is the same as the wedge 140 composed of the three divided wedge pieces described above, and therefore will not be described again here.

[0044] Fig. 9(A) shows a plan view of sleeve S10 that uses a headed hexagon socket head bolt (hereinafter referred to as a cap bolt) T10 as the connecting member, which constitutes intermediate fixing device 30. Fig. 9(B) shows a plan view of sleeve S11 that uses a headless hexagon socket head bolt (a fully threaded bolt, also known as a set screw, hereinafter referred to as a fully threaded bolt) T20 as the connecting member. Fig. 9(C) shows a plan view of sleeve S20 that is different from sleeve S10 and sleeve S11. Note that although sleeve S20 shown in Fig. 9(C) uses cap bolt T10 as the connecting member, a fully threaded bolt T20 may also be used as the connecting member.

[0045] These slit wall surface connection types shown in Figure 9 differ from the inner tube outer tube type (split type) described above in that they have a taper that can be combined with the wedge W, and a slit portion into which the new or existing PC steel B can be inserted when viewed from a plane perpendicular to the longitudinal direction of the new or existing PC steel B, and the opposing wall surfaces at this slit portion are connected using a connecting member, thereby regulating the spacing of the slit portion when viewed from a perpendicular plane, and they function as a sleeve that can be combined with the wedge W.

[0046] Although the sleeve S10 shown in FIG. 9(A) and the sleeve S11 shown in FIG. 9(B) use different connecting members (a cap bolt T10 in FIG. 9(A) and a fully threaded bolt T20 in FIG. 9(B)), the sleeve structure is the same except that the hole provided in section B10 is hole H10 (sleeve S10) and internally threaded hole H11 (sleeve S11). The sleeves S10 and S11 have a hollow cylindrical shape with an eccentric hollow portion (in which a wedge 140 and new or existing prestressing steel B are housed). Due to the eccentricity, the thicker side (the side where sections B10 and B12 are located) has a slit portion into which new or existing prestressing steel B can be inserted, and the opposing wall surfaces at the slit portion are connected using a connecting member.

[0047] When the connecting member is a cap bolt T10, as in the sleeve S10 shown in Figure 9(A), it has a female threaded hole H12 provided in at least one of the opposing wall surfaces (here, one of the wall surfaces) in the slit portion (here, the wall surface on the part B12 side), and a hole H10 provided in the other wall surface (here, the wall surface on the part B10 side), and the male thread of the cap bolt T10 passed through the hole H10 (not a threaded hole but a through hole) is screwed into the female threaded hole H12, connecting the opposing wall surfaces, thereby regulating the spacing of the slit portion when viewed from a vertical plane and functioning as a sleeve that can be combined with the wedge W.

[0048] In contrast, when the connecting member is a fully threaded bolt T20, as in the sleeve S11 shown in FIG. 9(B), the sleeve S11 has a female threaded hole H12 provided in at least one (here, both) of the opposing wall surfaces in the slit (here, the wall surface on the side of the portion B12), and a female threaded hole H11 provided in the other wall surface (here, the wall surface on the side of the portion B10). The male thread of the fully threaded bolt T20 threaded into the female threaded hole H11 is threaded into the female threaded hole H12, connecting the opposing wall surfaces, thereby restricting the spacing of the slits as viewed from a vertical plane, and functioning as a sleeve that can be combined with the wedge W. In the sleeve S11 shown in FIG. 9(B), not only is a female threaded hole H12 provided on the portion B12 side, but also a female threaded hole H11 is provided on the portion B10 side, and a fully threaded bolt T20 is used as a connecting member. Therefore, compared to the sleeve S10 shown in FIG. 9(A), in which a hole H10 is provided on the portion B10 side instead of a female threaded hole, and a cap bolt T10 is used as a connecting member. , the difference is that excessive tightening by the connecting member can be prevented.

[0049] Next, compared to the sleeve S10 shown in FIG. 9(A) and the sleeve S11 shown in FIG. 9(B), the sleeve S20 shown in FIG. 9(C) has a hollow prismatic shape with an eccentric hollow portion (in which the wedge 140 and the new or existing prestressing steel strand B are housed). That is, while the sleeve S10 shown in FIG. 9(A) and the sleeve S11 shown in FIG. 9(B) have a hollow cylindrical shape, the sleeve S20 shown in FIG. 9(C) has a hollow prismatic shape. Furthermore, the sleeve S20 is similar to the sleeves S10 and S11 in that, due to the eccentricity, the thicker-walled side (the side where the portions B10 and B12 are located) has a slit portion into which the new or existing prestressing steel strand B can be inserted, and the opposing wall surfaces of the slit portion are connected by a connecting member, thereby restricting the spacing of the slit portion as viewed from a vertical plane, and the sleeve S20 functions as a sleeve that can be combined with the wedge W.

[0050] 9(A), the sleeve S20 functions as a sleeve that can be combined with the wedge W by restricting the spacing between the slits as viewed from a vertical plane when the male thread of a cap bolt T10 passed through hole H10 (not a tapped hole but a through hole) is threaded into female threaded hole H12, connecting the opposing wall surfaces. As described above, the sleeve S20 shown in FIG. 9(C) uses cap bolt T10 as the connecting member, but a fully threaded bolt T20 may also be used as the connecting member. In this case, the sleeve S20 functions as a sleeve that can be combined with the wedge W by restricting the spacing between the slits as viewed from a vertical plane when the male thread of a fully threaded bolt T20 passed through female threaded hole H11 is threaded into female threaded hole H12, connecting the opposing wall surfaces.

[0051] An intermediate anchor 30 having such a structure is attached to a new or existing prestressing steel member B as follows. As described above, if the prestressing steel member B to be fixed by the intermediate anchor is embedded in concrete, an exposure step of chipping the concrete to expose the tensioned prestressing steel member B is required before the wedge attachment step described below. Below, we will explain the case where the intermediate anchor 30 shown in Figure 9(A) is used. Although not shown, in the wedge installation step, two or more divided wedge pieces (here, it is divided into three, so that there are three wedge pieces 142, wedge piece 144, and wedge piece 146) are installed on the exposed new or existing PC steel B so that the narrowing direction of the taper 140T of the wedge 140 is toward the surface (here, the direction shown in the side view of Figure 3).

[0052] In the sleeve mounting step, a sleeve S10 having a slit portion is mounted on the exposed new or existing prestressing steel B so that the narrowing direction of the taper 100T of the sleeve 100 is toward the surface (here, the direction shown in the side view of FIG. 3). More specifically, the new or existing prestressing steel B is inserted through the slit portion of the sleeve S10 and mounted. Next, the male thread of the cap bolt T10 is passed through a hole H10 (not a threaded hole but a through hole) provided in a portion constituting one of the opposing wall surfaces of the slit portion of the sleeve S10, and is screwed into the female threaded hole H12, connecting the opposing wall surfaces, thereby regulating the spacing of the slit portion as viewed from a vertical plane, and allowing the sleeve to function as a sleeve that can be combined with the wedge W (sleeve functioning step). In this way, in the sleeve S10 having a slit portion, connecting the opposing wall surfaces of the slit portion allows the spacing of the slit portion as viewed from a vertical plane to be regulated, allowing the sleeve to function as a sleeve (here, sleeve 100) that can be combined with the wedge W.

[0053] Finally, two or more split welds attached to the exposed new or existing prestressing tendon B are In an insertion step, the wedge piece (here, three wedge pieces 142, 144, and 146 because it is divided into three) is inserted into the sleeve 100 so that the direction of the taper 140T of the wedge 140 matches the direction of the taper 100T of the sleeve 100 and the sleeve 100 can function as a sleeve that can be combined with the wedge 140. In this way, the intermediate fixing device 30 is attached to the new or existing PC steel member B.

[0054] <Evaluation> The evaluation of such intermediate fixing device 30 and the construction method using this intermediate fixing device 30 (intermediate fixing construction method) will be explained with reference to Figure 10, along with the results of testing using test specimens and reference weights (including wedges). The prior art is the intermediate fixing device described in Patent Publication No. 2018-017029, which uses an intermediate fixing device 30 that has a configuration in which a wedge is combined with a sleeve and is tightened with four bolts, and Example 2 is the intermediate fixing device 30 shown in Figure 9(A), Example 3 is the intermediate fixing device 30 shown in Figure 9(B), Example 4 is the intermediate fixing device 30 shown in Figure 9(C), and Example 5 is the intermediate fixing device 30 shown in Figures 4 to 6.

[0055] As shown in Figure 10(A), compared to the prior art (two-piece sleeve, four fastening bolts, reference weight 8.8 kg), Example 2 (no split sleeve, two fastening bolts, reference weight 6.2 kg), Example 3 (no split sleeve, two fastening bolts, reference weight 6.1 kg), Example 4 (no split sleeve, two fastening bolts, reference weight 6.8 kg), and Example 5 (two-piece sleeve, two fastening bolts, reference weight 8.0 kg) showed a reduction in the number of parts, weight, and man-hours required for fastening, improving workability.

[0056] Next, the results of the performance confirmation test (static tensile test) are shown in FIG. 10(B). The test outline involves placing a 32mm prestressing steel rod (Type B, No. 2) (as an example of prestressing steel material) in a horizontal tensile testing machine, and conducting a tensile test with one end secured to a fixing nut commonly used for prestressing steel rods and the other end secured to the intermediate fixing device of the present invention. The maximum load during the test is recorded, and the anchoring efficiency, which indicates the ratio of the maximum load to the standard maximum tensile load (949kN) of the prestressing steel rod, is calculated.

[0057] The results of such tests are shown in Figure 10(B). In Examples 2 to 4, the anchoring efficiency was 100% or more, and the fracture location was at the anchoring nut, not at the location of the intermediate anchor according to the present invention, confirming sufficient performance as a fastener. Note that, for Example 3, similar performance can be expected by using the same shape and bolt diameter as Example 2. Furthermore, for Example 5, although the anchoring efficiency is lower than the other Examples, this is because the maximum load is determined by the fracture of the shear key K. Therefore, by reviewing the cross-sectional shape of the shear key K, etc., it is expected that the anchoring efficiency will increase. As described above, it is possible to provide an intermediate fixing device with excellent workability that can be suitably used for newly installed or existing prestressed concrete steel members in a tensioned state, and an intermediate fixing construction method using the same.

[0058] <Modification> Below, we will explain intermediate fixing devices (suitably used for tensioned prestressing steel members in the middle of a new or existing concrete structure) according to modified embodiments of the present invention. The intermediate fixing devices according to the first modified embodiment and the second modified embodiment described below are intended to make it easy to check and judge the construction status when setting wedges (screws, pins) in a small, dark space, and more specifically, are provided with a structure for facilitating confirmation of the presence of the wedge itself and confirmation that the wedge has been maintained in its set position (prevention of falling off). Note that other than confirmation of the presence of the wedge itself and confirmation that the wedge has been maintained in its set position (prevention of falling off), intermediate fixing devices are suitable for use on tensioned prestressing steel members in the middle of a new or existing concrete structure. The intermediate fixing method preferably used is the same as that described above, and therefore will not be repeated here. In the following, the same symbols are used for components (such as wedges) having the same structure as that described above, and since the structure and effects are the same, they will not be described again here.

[0059] Furthermore, the intermediate fixing devices according to the two modifications described below are based on the intermediate fixing device shown in Figure 7. However, the sleeve is not limited to the one shown in Figure 7, in which the sleeve is divided into an inner sleeve piece with an external thread and an outer sleeve piece with an internal thread that threads onto the external thread of the inner sleeve piece. The inner sleeve piece and the outer sleeve piece are integrated into a sleeve by threading the internal and external threads together. For example, the inner sleeve piece and the outer sleeve piece may be integrated into a sleeve by threading a set screw inserted through a set screw mounting hole into a set screw tap. Note that, for ease of understanding of these modifications, some cross sections are not hatched, and new or existing prestressing steel strands B are only shown in some of the drawings. Also, Figure 11(G) shows the AA cross section of Figure 11(F), and Figure 12(G) shows the AA cross section of Figure 12(F).

[0060] <<First Modification>> As shown in Figure 11, the intermediate fixing device of this modified example is a pressure plate type, and the presence of the wedge itself can be confirmed by providing a protrusion at the rear end of the wedge that protrudes from the rear end of the sleeve to make it visible, and the wedge's set position is maintained (prevented from falling off) by providing a pressure plate that can be connected to the sleeve with bolts, and pressing this pressure plate to a specified position with bolts.

[0061] More specifically, as shown in Figure 11(E) and Figure 11(A) showing the AA cross section of Figure 11(E), the pressure plate 300 is a flat plate made of, for example, metal, having a cutout portion 324 into which the new or existing PC steel B can be inserted when viewed from a plane perpendicular to the longitudinal direction of the new or existing PC steel B, and has a bolt hole 302 for connecting this pressure plate 300 to the sleeve 2100 described later with a bolt 310 (more specifically, by screwing together the female threaded hole 2222 provided in the sleeve piece 2220 on the outer tube side and the bolt 310).

[0062] As shown in FIG. 11(B), the wedge 340 is the three-piece wedge 140 described above, and is provided with a protrusion 342 at the rear end of the wedge 340 that protrudes from the rear end of the sleeve 2100. As shown in Figure 11(C), the sleeve piece 2220 on the outer tube side is provided with an internally threaded hole 2222 having an internal thread for threading onto the bolt 310 in the sleeve piece 220 on the outer tube side. As shown in Figure 11(D), the sleeve piece 210 on the inner tube side is the same as the sleeve piece 210 on the inner tube side described above, and is therefore given the same reference numeral. The sleeve 2100 in the intermediate fixing device according to this modified example is composed of the sleeve piece 2220 on the outer tube side shown in Figure 11(C) and the sleeve piece 210 on the inner tube side shown in Figure 11(D).

[0063] In the intermediate fixing device of this modified example having such a structure, the method of confirming the presence of the wedge itself and the maintenance of the wedge's set position (preventing it from falling off) will be described below with reference to Figures 11(E) to 11(G). When everything other than the pressure plate 300 and the bolt 310 shown in Figure 11(A) is assembled to the newly installed or existing PC steel B as shown in Figure 11(F), the pressure plate 300 is set in the direction of the black arrow shown in Figure 11(E) to the intermediate fixing device to which everything other than the pressure plate 300 and the bolt 310 has been assembled to the newly installed or existing PC steel B so that the positions of the bolt hole 302 and the female thread hole 2222 match.

[0064] Bolt 310 is passed through bolt hole 302 of presser plate 300, and bolt 310 is screwed (here fully at two locations, top and bottom) into female threaded hole 2222. During this operation process, the presence of wedge 340 itself can be easily confirmed visually by checking protrusion 342 that protrudes from the rear end of sleeve 2100 at the rear end of wedge 340. Furthermore, because presser plate 300 can be securely connected by screwing together sleeve 2100 and bolt 310, presser plate 300 can be pressed down by bolt 310 to a predetermined position (a position where bolt 310 is fully screwed into female threaded hole 2222), which makes it easy to ensure the set position and prevent it from falling off.

[0065] <<Second Modification>> As shown in Figure 12, the intermediate fixing device of this modified example is a wire clip type, and the presence of the wedge itself is confirmed by visually checking that the wire clip is in the specified position, as the position of the wire clip would not be determined without the wedge being present.The set position of the wedge is maintained (prevented from falling off) by restraining the end of the wedge with the wire clip and fixing the end of the wire clip to the sleeve, thereby determining the positional relationship between the wedge and the sleeve.

[0066] 12(A), the wire clip 400 is a metal wire having a predetermined shape that is symmetrical in the vertical direction of the paper of Fig. 12(A). The wire clip 400 comprises an insertion piece 402 that is inserted into an insertion hole 2212 provided on the end face of a sleeve 2200 (more specifically, of the sleeve piece 2210 on the inner cylinder side) described later, the end face piece 404 that is bent at a substantially right angle from the insertion piece 402 (in the plan view shown in Fig. 12(A)) and positioned on the end face of the sleeve 2200 in the direction where the taper narrows; 12(F))。 Constraining end surface piece 408 is bent at a right angle from the outer peripheral surface piece 406 (in the plan view shown in Figure 12 (A)) and is positioned at the end surface of the sleeve 2200 in the direction in which the taper widens, and is an arc-shaped constraining arc piece 410 (seen from the direction shown in Figure 12 (F)) that is fitted into a constraining groove 148 provided on the end surface of the wedge 140 in the direction in which the taper widens.

[0067] The characteristic structure of this wire clip 400 is that it has an insertion piece 402 that fits into an insertion hole 2212 provided on the end face of the sleeve 2200 in the direction where the taper narrows, and an arc-shaped restraining arc piece 410 that fits into the restraining groove 148 of the wedge 140. Note that the dimension L in Figure 12(A) corresponds to the longitudinal length of the new or existing PC steel B in the sleeve 2200. As shown in Fig. 12(B), the wedge 140 is the same as the three-piece wedge 140 described above, and is therefore given the same reference numeral. Note that in Fig. 4(B), the reference numeral of the restraining groove 148 is not given to the wedge 140.

[0068] As shown in Fig. 12(C), the inner tube side sleeve piece 2210 is provided with a fitting hole 2212 into which the fitting piece 402 of the wire clip 400 fits into the inner tube side sleeve piece 210 described above. Note that as shown in Fig. 12(C), the outer tube side sleeve piece 220 is the same as the outer tube side sleeve piece 220 described above, and is therefore given the same reference numeral. The outer tube side sleeve piece 220 shown in Fig. 12(C) and the inner tube side sleeve piece 2210 shown in Fig. 12(D) constitute the sleeve 2200 in the intermediate fixing device according to this modified example. In the intermediate fixing device of this modified example having such a structure, the method of confirming the presence of the wedge itself and the maintenance of the wedge's set position (preventing it from falling off) will be described below with reference to Figures 12(F) to 12(G).

[0069] When a wire clip other than the wire clip 400 shown in FIG. 12(A) is assembled to a new or existing prestressing steel beam B, as shown in FIGS. 12(E) and 12(G), the wire clip 400 is set by fitting the insertion piece 402 of the wire clip 400 into the insertion hole 2212 provided on the end face of the sleeve 2200 in the direction in which the taper narrows, and fitting the restraining arc piece 410 of the wire clip 400 into the restraining groove 148 of the wedge 140. During this work process, the presence of the wedge 140 itself can be easily confirmed by visually confirming that the wire clip 400 is in a predetermined position. Furthermore, by using the wire clip 400 to restrain the restraining groove 148 at the end of the wedge 140 and fixing the end of the wire clip 400 (the insertion piece 402) to the sleeve (the insertion hole 2212), the relative positions of the wedge and the sleeve are determined, which easily ensures the set position and prevents it from falling off.

[0070] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. For example, the following changes are possible: The intermediate fixing device for existing PC steel bars (intermediate fixing device 30) is composed of a wedge that grips the new or existing PC steel material B and a sleeve that stores the wedge, and it is preferable that the wedge and sleeve are made of metal or resin. The wedge and sleeve may have any structure as long as they can be attached to the existing PC steel rods, and the structure described above is merely one example. The wedge may be divided into two or more parts, and the sleeve may be one in which the halves can be fastened together with a bolt, or may have a slit (cutout) through which the PC steel rod passes, and may be in the shape of a cylinder, hollow cylinder, solid cylinder, square pillar, or polygonal pillar.

[0071] The sleeve may be tapered in one direction (intermediate fixing device 30) or in two opposing directions (intermediate fixing device 32) relative to the longitudinal direction (material axis) of the PC steel bar. The taper angle of the sleeve and wedge is optional, but is preferably between 5 and 15 degrees. The longitudinal length of the PC steel rods for the sleeve and wedge can be any length, but it is preferable that it be approximately 20 mm to 200 mm. The material used for the sleeve and wedge may be metal, resin, or synthetic fiber. [Industrial Applicability]

[0072] The present invention is preferable for an intermediate fixing device that can be suitably used for newly installed or existing prestressed PC steel members in a tensioned state, and an intermediate fixing construction method using the same, and is particularly preferable in terms of its excellent workability. [Explanation of symbols]

[0073] 100 sleeves 110, 120 sleeve pieces 140 Wedge 142, 144, 146 Wedge pieces 200 sleeves 210, 220 sleeve pieces 240 Wedge 242, 244 Wedge pieces S sleeve W Wedge B New or existing prestressing tendons

Claims

1. An intermediate anchor suitable for use with tensioned PC steel members in the middle of a new or existing concrete structure, a wedge divided into two or more wedge pieces when viewed from a plane perpendicular to the longitudinal direction of the PC steel; a sleeve having a taper that can be combined with the wedge and a slit into which the PC steel member can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel member, The opposing wall surfaces of the slit portion are connected using a connecting member, thereby restricting the spacing of the slit portion as viewed from the vertical plane, and the slit portion functions as a sleeve that can be combined with the wedge, The connecting member includes a female screw hole provided in at least one of the opposing wall surfaces and a male screw passed through a hole provided in the other wall surface, An intermediate fixing device for PC steel, characterized in that the spacing of the slit portions as viewed from the vertical surface is regulated by threading the male screw into the female threaded hole to connect the wall surfaces.

2. An intermediate fixing device suitable for use with tensioned PC steel members in the middle of a new or existing concrete structure, a wedge divided into two or more wedge pieces when viewed from a plane perpendicular to the longitudinal direction of the PC steel; a sleeve divided into an inner sleeve piece having a taper that is combined with the wedge and an outer sleeve piece that is provided on the outside of the inner sleeve piece, With respect to the inner sleeve piece and the outer sleeve piece, at least the inner sleeve piece has a notch into which the PC steel can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel, The sleeve piece on the inner cylinder side and the sleeve piece on the outer cylinder side are joined together to form an integrated sleeve that functions as a sleeve to be combined with the wedge, a male thread provided on the outer peripheral surface of the sleeve piece on the inner tube side and a female thread provided on the inner peripheral surface of the sleeve piece on the outer tube side are threadedly engaged with each other, and the sleeve piece on the inner tube side and the sleeve piece on the outer tube side are joined together to form an integrated sleeve, The sleeve further includes a flat plate joined to the sleeve at an end surface in the direction in which the taper widens and that is perpendicular to the longitudinal direction of the PC steel member, The plate has a notch portion into which the PC steel can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel, and into which a wedge protrusion provided at an end of the wedge in a direction in which the taper widens can protrude, This intermediate fixing device for PC steel is characterized in that by joining the plate to a predetermined position on the end face of the sleeve, the wedge is ensured to be positioned at the set position of the sleeve, the wedge is prevented from falling off, and the presence of the wedge can be confirmed by visually checking the wedge protrusion protruding from the cutout portion of the plate.

3. An intermediate fixing device suitable for use with tensioned PC steel members in the middle of a new or existing concrete structure, a wedge divided into two or more wedge pieces when viewed from a plane perpendicular to the longitudinal direction of the PC steel; a sleeve divided into an inner sleeve piece having a taper that is combined with the wedge and an outer sleeve piece that is provided on the outside of the inner sleeve piece, With respect to the inner sleeve piece and the outer sleeve piece, at least the inner sleeve piece has a notch into which the PC steel can be inserted when viewed from a plane perpendicular to the longitudinal direction of the PC steel, The sleeve piece on the inner cylinder side and the sleeve piece on the outer cylinder side are joined together to form an integrated sleeve that functions as a sleeve to be combined with the wedge, a male thread provided on the outer peripheral surface of the sleeve piece on the inner tube side and a female thread provided on the inner peripheral surface of the sleeve piece on the outer tube side are threadedly engaged with each other, and the sleeve piece on the inner tube side and the sleeve piece on the outer tube side are joined together to form an integrated sleeve, Further comprising a three-dimensionally shaped wire clip; The wire clip is A straight portion of the sleeve corresponding to the length of the PC steel member in the longitudinal direction; an arc portion that is fitted into a wedge groove that is provided on the outer periphery of the end of the wedge in the direction in which the taper widens, on the side of the sleeve where the taper widens relative to the linear portion; and an insertion piece that is inserted into a sleeve hole provided on an end face of the sleeve in the direction in which the taper narrows, the end face being perpendicular to the longitudinal direction of the PC steel, on the side of the sleeve where the taper narrows from the linear portion, An intermediate fixing device for PC steel, characterized in that the arc portion of the wire clip is fitted into the wedge groove portion and the fitting piece of the wire clip is fitted into the sleeve hole portion, thereby ensuring that the wedge is positioned at the set position of the sleeve and preventing the wedge from falling off, and allowing the presence of the wedge to be confirmed by visually checking the wire clip arranged along the outer circumference of the sleeve.

4. An intermediate fixing method using the intermediate fixing tool according to any one of claims 1 to 3, an exposure step of chipping the concrete when the PC steel member fixed by the intermediate fixing device is embedded in concrete to expose the PC steel member in a tensioned state; a wedge installation step of installing two or more divided wedge pieces on the tensioned PC steel member so that the direction in which the taper of the wedge narrows is the direction in which compressive force is introduced into the concrete; a sleeve attachment step of attaching a sleeve having a structure that can be attached to the PC steel member to the tensioned PC steel member so that the direction in which the taper of the sleeve narrows is the direction in which the compressive force is introduced into the concrete; a sleeve functionalization step of causing the sleeve to function as a sleeve that can be combined with the wedge; An intermediate anchoring method for PC steel members, comprising an insertion step of inserting two or more wedge pieces attached to the PC steel members in the tensioned state in the divided state into the sleeve functioning as a sleeve by aligning the taper direction of the wedges with the taper direction of the sleeve.

5. The PC steel intermediate anchoring method according to claim 4, wherein the inserting step includes a step of manually inserting the wedge into the sleeve by a worker without using a jack.

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