Precast concrete member joint structure and precast concrete member joint method

Abstract

To provide a precast concrete member joint structure and a precast concrete member joint method which inhibit cracks from occurring under low tensile forces and enable efficient construction.SOLUTION: A joint structure 1 comprises a first-axial-direction reinforcement bars 31 protruding on the end surface of one precast slab 2, a second-axial-direction reinforcement bars 32 protruding on the end surface of the other precast slab 2, and a filled concrete 6 placed between the pair of precast slabs 2, 2. A total of the protrusion length of the first-axial-direction reinforcement bar 31 and the protrusion length of the second-axial-direction reinforcement bar 32 is less than the spacing between the pair of precast slabs 2, 2. The central axis of the first-axial-direction reinforcement bar 31 and the central axis of the second-axial-direction reinforcement bar 32 are eccentric and parallel. Joint reinforcement bars 4 are arranged between the first-axial-direction reinforcement bars 31 and the second-axial-direction reinforcement bars 32 in a direction either parallel to or oblique to the central axis of the first-axial-direction reinforcement bar 31 and the central axis of the second-axial-direction reinforcement bar 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint structure for precast concrete members and a method for joining precast concrete members. [Background technology]

[0002] Precast concrete members arranged side by side are often connected via filler concrete or filler mortar (hereinafter simply referred to as "filler") poured into the joints. At the joint portion, axial reinforcing bars are protruding from the end faces of both precast concrete pieces, and it is common for these axial reinforcing bars to serve as joint members. When connecting rebars, it is common to use lap joints, but to ensure the necessary joint length for the rebars, the width of the joint becomes larger. When the joint width becomes larger, the amount of filling material that needs to be poured increases, and the effort required for pouring it also increases.

[0003] In some cases, the width of the joint can be reduced by processing the reinforcing bar serving as the joint member in the joint into a loop shape. For example, Patent Document 1 discloses a deck joint structure in which the end faces of precast decks with protruding loop reinforcements are butted together with a specified gap between them, distribution bars are arranged to cross the loop reinforcements, and filler concrete is poured into the gap between the end faces. However, when loop reinforcements are used as joint members, the member height may increase depending on the diameter of the loop. In addition, in order to obtain a strength equivalent to the tensile strength of the rebar base material using a loop joint, it is necessary to arrange the horizontal reinforcement within the loop, but this arrangement is time-consuming. Furthermore, when PC steel is arranged, the loop reinforcement and horizontal reinforcement may interfere with the PC steel.

[0004] In addition, the width of the joint may be reduced by forming a widened portion (anchoring portion) at the end of the reinforcing bar as a joint member. For example, Patent Document 2 discloses a joint structure in which axial rebars protruding from the end faces of opposing precast concrete members are arranged on the same axis at the joint, anchors are formed at the ends, and further, joint rebars with anchors formed at both ends are arranged between adjacent axial rebars in parallel to the axial rebars. In the joint structure of Patent Document 2, cracks may occur and progress between the axial rebars arranged on the same axis even when the axial tensile force is small. Also, Patent Document 3 discloses a joint structure in which axial reinforcing bars, each having an anchor formed at an end protruding from the end face of an opposing precast member, are joined by a lap joint at the joint section. However, in the joint structure of Patent Document 3, when axial reinforcing bars are arranged up, down, left, and right, such as in a box culvert, it is necessary to position the precast concrete member by sliding it from the axial direction, which may make efficient construction difficult. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-236258 A [Patent Document 2] JP 2020-063617 A [Patent Document 3] Patent Publication No. 2021-055531 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to propose a joint structure for precast concrete members and a method for joining precast concrete members that suppress the occurrence of cracks at low tensile forces and enable efficient construction. [Means for solving the problem]

[0007] In order to solve such problems, the joint structure of the precast concrete member of the present invention is for joining a pair of precast concrete members arranged with a gap therebetween, and includes a first axial reinforcing bar protruding from an end face of one of the precast concrete members, a second axial reinforcing bar protruding from an end face of the other precast concrete member, and concrete filling between the pair of precast concrete members. An anchor having a width larger than the diameter of each reinforcing bar is formed at the end of the first axial reinforcing bar and the end of the second axial reinforcing bar. The sum of the protruding length of the first axial reinforcing bar from one of the precast concrete members and the protruding length of the second axial reinforcing bar from the other precast concrete member is smaller than the interval between the pair of precast concrete members. Furthermore, the central axis of the first axial reinforcing bar and the central axis of the second axial reinforcing bar are eccentric and parallel. Then, a joint reinforcing bar with an anchor formed at both ends is arranged between the first axial reinforcing bar and the second axial reinforcing bar, in a direction parallel or inclined to the central axis of the first axial reinforcing bar and the central axis of the second axial reinforcing bar.

[0008] The method for joining precast concrete members of the present invention is to join a pair of precast concrete members with axial reinforcing bars protruding from their end faces in a continuous manner. The method includes an arrangement step of arranging one of the precast concrete members at a distance from the other precast concrete member, an arrangement step of arranging a joining reinforcing bar between the precast concrete members, and a pouring step of pouring filler concrete between the precast concrete members. An anchor having an outer shape larger than the cross-sectional shape of the axial reinforcing bar is formed at the tip of the axial reinforcing bar, and an anchor having an outer shape larger than the cross-sectional shape of the joining reinforcing bar is formed at both ends of the joining reinforcing bar. The central axis of the axial reinforcing bar of one of the precast concrete members and the central axis of the axial reinforcing bar of the other precast concrete member are eccentric and parallel. In the disposing step, the other precast concrete member is disposed so that the distance between the precast concrete members is greater than the sum of the protruding length of the axial reinforcing bar of one of the precast concrete members and the protruding length of the axial reinforcing bar of the other precast concrete member. In the reinforcing bar arrangement step, the connecting reinforcing bar is arranged between the axial reinforcing bar of one of the precast concrete members and the axial reinforcing bar of the other precast concrete member, in a direction parallel to or inclined with respect to the central axes of both axial reinforcing bars.

[0009] According to this joint structure for precast concrete members and method for joining precast concrete members, the central axes of the axial reinforcing bars protruding from the end faces of the opposing precast concrete members are eccentric with respect to each other, and the length of both axial reinforcing bars does not overlap, so that the installation method for arranging the precast concrete members is not limited to sliding from the axial direction. In addition, the central axes of the axial reinforcing bars of opposing precast concrete members are not arranged coaxially but are offset from each other, which helps to prevent cracks from occurring even at low tensile forces. The axial rebars are joined together by lap joints via connecting rebars.

[0010] If the structure further includes a transverse reinforcing bar arranged in a direction intersecting the first axial reinforcing bar, the second axial reinforcing bar, and the joint reinforcing bar, the ultimate tensile strength in the axial direction can be improved by the transverse reinforcing bar anchored to the anchor. The transverse reinforcing bar also resists lateral tensile forces. In the thickness direction of the filler concrete, it is desirable that the cover of the joint reinforcing bars is equal to or greater than the cover of the axial reinforcing bars. In this way, the thickness of the member does not increase even when the joint reinforcing bars are arranged. It is desirable to place tension members through both precast concrete members at the middle of the thickness of the filler concrete. This will reduce the crack width at the service limit. In addition, by increasing the tension, the occurrence of cracks can be suppressed. Furthermore, the tension members function effectively as tensile steel against torsion. Effect of the Invention

[0011] According to the joint structure for precast concrete members and the method for joining precast concrete members of the present invention, the occurrence of cracks at low tensile forces can be suppressed and efficient construction can be achieved. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a plan view showing the joint structure of the first embodiment. [Diagram 2] FIG. 2 is a side view showing the joint structure of the first embodiment. [Diagram 3] 2 is a flowchart showing the steps of a precast deck joining method according to the present embodiment. [Figure 4] FIG. 6 is a plan view showing a joint structure of a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] First Embodiment In the first embodiment, a joint structure 1 for joining a plurality of precast decks 2 laid continuously in a bridge axis direction in bridge construction will be described. The joint structure 1 is shown in FIGS. As shown in Figures 1 and 2, the joint structure 1 joins a pair of precast deck slabs 2, 2 arranged with a gap 11 between them, and includes axial reinforcing bars 3, joining reinforcing bars 4, transverse reinforcing bars 5, filling concrete 6, and tendons 7.

[0014] The precast slab 2 is a precast concrete member made of reinforced concrete. As shown in Figures 1 and 2, inside the precast slab 2, two tiers of vertical slab reinforcements 21 are arranged along the bridge axis direction (left and right direction in the drawings), and horizontal slab reinforcements 22 are arranged to intersect with the vertical slab reinforcements 21. In addition, axial reinforcing bars 3 are provided to protrude from end faces 23 of the precast slab 2.

[0015] As shown in Fig. 2, the axial rebars 3 in this embodiment are the parts of the deck vertical bars 21 that protrude from the end faces 23 and are disposed in the gaps 11. The axial rebars 3 in this embodiment are SD345. The axial rebars 3 may be embedded in the end faces 23 of the precast deck 2 separately from the deck vertical bars 21. The standard of the rebars that constitute the axial rebars 3 is not limited. As shown in Figure 1, the central axis of the first axial reinforcing bar 31, which is the axial reinforcing bar 3 protruding from the end face 23 of one precast deck 2, and the central axis of the second axial reinforcing bar 32, which is the axial reinforcing bar 3 protruding from the end face 23 of the other precast deck 2, are eccentric and parallel.

[0016] At the end of the first axial reinforcing bar 31 and the end of the second axial reinforcing bar 32, an anchor 33 having a width larger than the diameter of each reinforcing bar (an outer shape larger than the cross-sectional shape of the reinforcing bar) is formed. The anchor 33 in this embodiment is formed by fixing a rectangular steel plate to the end of the axial reinforcing bar 3. The method of fixing the anchor 33 to the axial reinforcing bar 3 is not limited, and may be, for example, welding, friction welding, or gas pressure welding. In addition, when the axial reinforcing bar 3 is threaded, a nut that can be screwed onto the axial reinforcing bar 3 may be used as the anchor 33, or a steel plate with a female thread may be used. In addition, the anchor 33 is not limited to one formed by joining a separate member (steel plate) to the axial reinforcing bar 3, and may be, for example, an enlarged diameter portion (so-called a knob) formed by forging the end of the reinforcing bar. The sum of the protruding length of the first axial reinforcing bar 31 from one precast floor slab 2, including the member thickness of the anchoring body 33, and the protruding length of the second axial reinforcing bar 32 from the other precast floor slab 2, including the member thickness of the anchoring body 33, is smaller than the distance (width of the gap 11) between a pair of precast floor slabs 2, 2. That is, a gap is secured between the anchoring body 33 of the first axial reinforcing bar 31 and the anchoring body 33 of the second axial reinforcing bar 32. The sum of the protruding length of the first axial reinforcing bar 31 and the protruding length of the second axial reinforcing bar 32 may be equal to the distance between the pair of precast floor slabs 2, 2.

[0017] As shown in Fig. 1, the connecting rebars 4 are rebars arranged parallel to the axial rebars 3 (first axial rebars 31 and second axial rebars 32) in the gaps 11 between the precast floor slabs 2. The rebar diameter of the connecting rebars 4 in this embodiment is equal to or smaller than the rebar diameter of the axial rebars 3. The covering of the connecting rebars 4 in the thickness direction of the filling concrete 6 is equal to or larger than the covering of the axial rebars 3 (first axial rebars 31 and second axial rebars 32). In addition, when the reinforcement of the joint structure 1 is dense, it is preferable to make the reinforcing bar diameter of the joint reinforcing bars 4 smaller than the reinforcing bar diameter of the axial reinforcing bars 3. An anchor 41 having an outer shape larger than the cross-sectional shape of the joint rebar 4 is formed on both ends of the joint rebar 4. The anchor 41 of the joint rebar 4 is formed by fixing a rectangular steel plate to the end of the joint rebar 4. The method of fixing the anchor 41 to the joint rebar 4 is not limited, and may be, for example, welding, friction welding, or gas pressure welding. In addition, when the joint rebar 4 is threaded, a nut that can be screwed into the joint rebar 4 may be used as the anchor 41, or a steel plate with a female thread may be used. In addition, the anchor 41 is not limited to one formed by fixing a separate member (steel plate) to the joint rebar 4, and may be, for example, an enlarged diameter portion (so-called a knob) formed by forging the end of the rebar.

[0018] The transverse reinforcing bars 5 are reinforcing bars arranged in the gaps 11 between the precast floor slabs 2 in a direction intersecting the axial reinforcing bars 3 and the connecting reinforcing bars 4. The transverse reinforcing bars 5 are arranged close to the anchors 33 of the axial reinforcing bars 3 or the anchors 41 of the connecting reinforcing bars 4.

[0019] The filler concrete 6 is a hardened concrete body filled between the precast deck slabs 2 (gaps 11). For the filler concrete 6, a material having the same compressive strength as the precast deck slab 2 is used. Note that the material constituting the filler concrete 6 is not limited, and for example, mortar may be used. The mix proportions of the filler concrete 6 may be determined appropriately. The tendons 7 are inserted through both precast floor slabs 2, 2 and disposed at the middle in the thickness direction of the filling concrete 6. The tendons 7 are made of, for example, PC steel bars, PC steel wires, PC strands, or the like.

[0020] Next, a method for joining precast floor slabs 2 (precast concrete members) will be described. Figure 3 shows the steps of the method for joining precast floor slabs 2. As shown in Figure 3, the method for joining precast floor slabs 2 includes a placement process S1, a reinforcing bar arrangement process S2, a casting process S3, and a tensioning process S4. In the installation step S1, one precast slab 2 is installed at a distance (gap 11) from the other precast slab 2. In the installation step S1, the precast slab 2 is laid so that the first axial reinforcing bar 31 and the second axial reinforcing bar 32 are arranged alternately at a distance in the axial direction and in a direction intersecting the axial direction. That is, the central axis of the first axial reinforcing bar 31 and the central axis of the second axial reinforcing bar 32 of the other precast concrete member are eccentric. In addition, the other precast concrete member is installed so that the distance between the precast slabs 2 is larger than the sum of the protruding length of the first axial reinforcing bar 31 and the protruding length of the second axial reinforcing bar 32. The installation work of the precast slab 2 is performed by suspending the other precast slab 2 from above after placing one precast slab 2 at a predetermined position. After laying the precast slab 2, the tendons 7 are inserted through the precast slabs 2, 2. Once the precast deck 2 has been laid, the sides and bottom of the gap 11 are covered with formwork (not shown) as necessary. Note that in cases where there is no risk of the filling concrete 6 flowing out from below the gap 11, such as when a main girder is provided below the gap 11, the formwork on the bottom of the gap 11 may be omitted.

[0021] In the reinforcement arrangement process S2, joint rebars 4 and transverse rebars 5 are arranged between the precast floor slabs 2 (gaps 11). The joint rebars 4 are arranged between the first axial rebar 31 and the second axial rebar 32 so as to be parallel to both axial rebars 3, 3. In the reinforcement arrangement process S2, the transverse rebars 5 are arranged in a position close to the anchors 33 of the axial rebars 3 or the anchors 41 of the joint rebars 4. In the pouring process S3, filler concrete 6 is poured between the precast floor slabs 2 (in the gaps 11). The filler concrete 6 is poured into a formwork that covers the gaps 11. The filler concrete 6 is cured, and when it has developed a predetermined strength, the formwork is removed. In the tensioning process S4, the tensioning material 7 is tensioned to introduce prestress into the precast deck 2.

[0022] According to the joint structure 1 and the joining method for precast concrete members of this embodiment, the axial reinforcing bars 3 protruding from the end faces of the opposing precast floor slabs 2 are long enough not to overlap, so the installation method for installing the precast floor slabs 2 is not limited to sliding from the axial direction. Even when the precast floor slab 2 to be laid later is lowered from above, the axial reinforcing bars 3 will not come into contact with each other. In addition, the central axes of the axial reinforcing bars 3, 3 of the opposing precast decks 2, 2 are not arranged coaxially but are misaligned, which makes it possible to suppress the occurrence of cracks even at low tensile forces. The first axial reinforcing bar 31 and the second axial reinforcing bar 32 protruding from the opposing precast deck slabs 2, 2 are joined by a lap joint between the two axial reinforcing bars 3, 3 via a connecting reinforcing bar 4 arranged across both axial reinforcing bars 3, 3 after the precast deck 2 is laid.

[0023] In addition, the ultimate tensile strength in the axial direction can be improved by the transverse reinforcing bars 5 that are anchored to the anchors 33 of the axial reinforcing bars 3 or the anchors 41 of the joint reinforcing bars 4. The transverse reinforcing bars 5 also resist lateral tensile forces. Since the covering of the joining reinforcing bars 4 in the thickness direction of the inter-filled concrete 6 is equal to or greater than the covering of the axial reinforcing bars 3, the thickness of the member does not increase even when the joining reinforcing bars 4 are arranged. In addition, the tension material 7 inserted through both precast floor slabs 2, 2 is disposed in the middle of the thickness direction of the filling concrete 6, so that the crack width at the service limit state can be reduced. Furthermore, by increasing the tension of the tension material 7, the occurrence of cracks can be suppressed. Furthermore, the tension material 7 effectively functions as a tensile steel material against torsion.

[0024] Second Embodiment In the second embodiment, similarly to the first embodiment, a joint structure 1 for joining a plurality of precast decks 2 laid continuously in the bridge axis direction during bridge construction will be described. Fig. 4 shows the joint structure 1 of the second embodiment. As shown in Fig. 4, the joint structure 1 joins a pair of precast floor slabs 2, 2 arranged with a gap 11 between them, and includes axial reinforcing bars 3, joint reinforcing bars 4, horizontal reinforcing bars 5, interfacial concrete 6, and tendons 7. Note that the details of the precast floor slabs 2, axial reinforcing bars, horizontal reinforcing bars 5, interfacial concrete 6, and tendons 7 are similar to those described in the first embodiment, and therefore will not be described in detail.

[0025] As shown in FIG. 4, the joint reinforcing bars 4 are arranged between the first axial reinforcing bars 31 and the second axial reinforcing bars 32 in the gaps 11 between the precast floor slabs 2. In this embodiment, the first joint reinforcing bars 42 are arranged parallel to the central axis of the first axial reinforcing bars 31 and the central axis of the second axial reinforcing bars 32, and the second joint reinforcing bars are arranged in a direction inclined to the central axis of the first axial reinforcing bars 31 and the central axis of the second axial reinforcing bars 32. The first joint reinforcing bars 42 and the second joint reinforcing bars 43 are arranged alternately in a direction perpendicular to the axial direction. The first joint reinforcing bars 42 and the second joint reinforcing bars 43 are arranged parallel to a plane including the central axis of the first axial reinforcing bars 31 and the central axis of the second axial reinforcing bars 32. In this embodiment, the rebar diameter of the joint rebar 4 is equal to or smaller than the rebar diameter of the axial rebar 3. The cover of the joint rebar 4 in the thickness direction of the filling concrete is equal to or larger than the cover of the axial rebar 3 (first axial rebar 31 and second axial rebar 32).

[0026] An anchor 41 having an outer shape larger than the cross-sectional shape of the joint rebar 4 is formed on both ends of the joint rebar 4. The anchor 41 of the joint rebar 4 is formed by fixing a rectangular steel plate to the end of the joint rebar 4. The method of fixing the anchor 41 to the joint rebar 4 is not limited, and may be, for example, welding, friction welding, or gas pressure welding. In addition, when the joint rebar 4 is threaded, a nut that can be screwed into the joint rebar 4 may be used as the anchor 41, or a steel plate with a female thread may be used. In addition, the anchor 41 is not limited to one formed by fixing a separate member (steel plate) to the joint rebar 4, and may be, for example, an enlarged diameter portion (so-called a knob) formed by forging the end of the rebar.

[0027] According to the joint structure 1 of the present embodiment, by inclining the joint rebars 4, the interval between the axial rebars 3 in the direction perpendicular to the axial direction can be made smaller than that of the joint structure 1 of the first embodiment. That is, it is possible to make the reinforcing bar pitch of the axial rebars 3 smaller than that of the axial reinforcing bars 3 in the first embodiment. Therefore, even if the shape of the precast floor slab 2 is relatively small, the necessary amount of reinforcing bars can be arranged. In addition, by adjusting the inclination angle of the joint rebars 4, placement errors of the axial rebars 3 and placement errors of the precast deck 2 can be easily accommodated. Other functions and effects of the joint structure 1 of the second embodiment are similar to those of the first embodiment, so detailed description thereof will be omitted.

[0028] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and each component can be appropriately modified without departing from the spirit of the present invention. In the above embodiment, the joint structure 1 of the precast floor slab 2 has been described, but the precast concrete member is not limited to a floor slab and may be, for example, a box culvert. All of the joint rebars 4 may be inclined with respect to the central axis of the axial rebars 3 . The horizontal reinforcing bars 5 do not necessarily have to be in contact with the anchors 33, 41. Furthermore, the horizontal reinforcing bars 5 may be arranged as necessary. The tendons 7 may be disposed as required. Similarly, the tensioning step S4 may be performed as required. The shape of the fixing bodies 33 and 41 is not limited to a rectangle, but may be, for example, another polygon, circle, ellipse, or the like. [Explanation of symbols]

[0029] 1 Joint structure (joint structure of precast concrete members) 11. Gap 2 Precast floor slabs (precast concrete components) 21 Deck vertical reinforcement 22 Deck slab horizontal reinforcement 23 End face 3 Axial reinforcement 31 First axial reinforcing bar 32 Second axial reinforcement 33 Fixer 4. Jointed Reinforcement Bars 41 Fixer 42 First joint rebar 43 Secondary joint rebar 5 Transverse Reinforcement 6. Filling concrete 7 Tensors

Claims

1. A joint structure for precast concrete members for joining a pair of precast concrete members arranged with a gap therebetween, A first axial reinforcing bar protruding from an end surface of one of the precast concrete members; A second axial reinforcing bar protruding from an end face of the other precast concrete member; and filling concrete filled between the pair of precast concrete members, An anchor having a width larger than the diameter of each reinforcing bar is formed at the tip of the first axial reinforcing bar and the tip of the second axial reinforcing bar, The sum of the protruding length of the first axial reinforcing bar from one of the precast concrete members and the protruding length of the second axial reinforcing bar from the other of the precast concrete members is smaller than the distance between the pair of precast concrete members, The central axis of the first axial reinforcing bar and the central axis of the second axial reinforcing bar are eccentric and parallel, A joint structure of a precast concrete member, characterized in that a connecting bar with anchors formed at both ends is arranged between the first axial reinforcing bar and the second axial reinforcing bar, in an orientation parallel to or inclined to the central axis of the first axial reinforcing bar and the central axis of the second axial reinforcing bar.

2. The joint structure of a precast concrete member as described in claim 1, further comprising a transverse reinforcing bar arranged in a direction intersecting the first axial reinforcing bar, the second axial reinforcing bar and the joint reinforcing bar.

3. A joint structure of a precast concrete member as described in claim 1, characterized in that the cover of the joining reinforcing bars in the thickness direction of the filling concrete is equal to or greater than the cover of the first axial reinforcing bars and the cover of the second axial reinforcing bars.

4. 2. A joint structure for precast concrete members as described in claim 1, characterized in that a tension member inserted into both of the precast concrete members is arranged in the middle of the thickness direction of the filling concrete.

5. A method for joining precast concrete members, comprising the steps of: connecting a pair of precast concrete members each having an axial reinforcing bar protruding from an end face of the precast concrete member; a placement step of placing one of the precast concrete members at a distance from the other of the precast concrete members; A reinforcing bar arrangement process for arranging joint reinforcing bars between the precast concrete members; A pouring step of pouring filler concrete between the precast concrete members, An anchor having an outer shape larger than the cross-sectional shape of the axial reinforcing bar is formed at the tip of the axial reinforcing bar, An anchor having an outer shape larger than the cross-sectional shape of the joint rebar is formed on both ends of the joint rebar, the central axis of the axial reinforcing bar of one of the precast concrete members and the central axis of the axial reinforcing bar of the other of the precast concrete members are eccentric and parallel; In the disposing step, the other precast concrete member is disposed so that the distance between the precast concrete members is greater than the sum of the protruding length of the axial reinforcing bar of one of the precast concrete members and the protruding length of the axial reinforcing bar of the other precast concrete member; A method for joining precast concrete members, characterized in that in the reinforcement step, the joining reinforcement is arranged between the axial reinforcement of one of the precast concrete members and the axial reinforcement of the other precast concrete member, in a direction parallel to or inclined to the central axes of both axial reinforcement bars.

Images