Installation method for half-precast member

Abstract

To provide an installing method for a half-precast member that can prevent the load from concentrating on a specific mounting point of a suspension material.SOLUTION: A process is carried out in which upper ends of suspension materials 5-1 to 5-8, whose lower ends are fixed to a half-precast member 1, are attached to a support material 4, and the half-precast member 1 is suspended and supported by the plurality of suspension materials 5-1 to 5-8 from the support material 4. In addition, as means to prevent rattling at attachment points of upper ends of the suspension materials 5-1 to 5-8 to the support material 4, the tension applied to each of the suspension materials 5-1 to 5-8 is set so that the tension of the suspension material to which tension has been applied previously does not become zero when tension is applied to another suspension material and the half-precast member 1 is lifted up.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for installing a half precast member. [Background technology]

[0002] When constructing RC (reinforced concrete) top plates for box culverts, water treatment facilities, etc., supports are placed closely on the underside of the top plate to suppress deformation of the formwork due to the load during construction.

[0003] Eliminating these supports is effective in streamlining construction, and for this reason, a half-precast member with steel embedded in a concrete precast slab that serves as the top slab's formwork is erected, and then the half-precast member is supported by being suspended from the suspension supports by multiple suspension members (for example, Patent Document 1, etc.). This method makes it possible to omit the formwork and supports on the underside of the top slab. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6252835 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above method, the load acting on the half precast member during construction is uniformly transmitted to the support material of the suspension shoring through each suspension member, ensuring a certain bending rigidity. Therefore, the issue is how to support the half precast member so that the load is not concentrated at a specific attachment point among the attachment points of these suspension members to the support material. In addition, since there are multiple suspension members, it is desirable for the method to be simple.

[0006] Furthermore, depending on the size of the top plate, the deflection of the half precast member that occurs when it is erected becomes large, and it becomes necessary to perform a lift to adjust the deflection before pouring concrete. In this case, it becomes necessary to attach the hanging material to the support material while ensuring the amount of lift, which increases the difficulty and complexity of the construction.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a method for installing half-precast members that can prevent loads from being concentrated at specific attachment points of the hanging material. [Means for solving the problem]

[0008] The first invention for solving the above-mentioned problems is a method for installing a half-precast member in which the half-precast member is supported by hanging it from a supporting material using a plurality of hanging members, the method comprising a step (a) of attaching the upper end of a first hanging member, the lower end of which is fixed to the half-precast member, to the supporting material, characterized in that in step (a), a specified measure is taken to prevent rattling at the attachment point of the upper end of the first hanging member to the supporting material.

[0009] In the present invention, when a half-precast member is suspended from a support material by multiple hanging members, measures are taken to prevent rattling at the attachment points of the first hanging member to the support material. This makes it possible to avoid the load from concentrating on a specific attachment point among the attachment points of the multiple hanging members to the support material. As a result, the load acting on the half-precast member during construction can be transmitted uniformly to the support material via each hanging member.

[0010] The specified measure is, for example, to set the tension applied to each of the first hanging materials in step (a) when tension is applied to a plurality of first hanging materials and the upper ends of each of the first hanging materials are attached to the support material so that the tension of the first hanging material to which tension has been applied does not become zero when tension is applied to another first hanging material as a result of the half-precast member being lifted. By controlling the tension in this manner, rattling can be easily and reliably prevented from occurring at the attachment point of the first hanging material to the support material.

[0011] In step (a), it is desirable that the upper end of the first hanging material is attached to the support material by tightening a nut on the upper side of the support material toward the support material. This makes it possible to control the tension of the first hanging material by the torque value when tightening the nut.

[0012] The specified measure may be, in step (a), tightening a nut on the upper end of a first hanging material toward the support material on the upper side of the support material, thereby placing a cushioning material between the nut and the support material when attaching the upper end of the first hanging material to the support material. In this way, by having the nut used to attach the first hanging material to the support material come into face contact with the cushioning material, it is possible to easily and reliably prevent rattling from occurring at the attachment point of the first hanging material to the support material.

[0013] It is desirable that the cushioning material be shared among a plurality of first hanging materials. This makes it easier to install the cushioning material.

[0014] Prior to step (a), it is also desirable to carry out step (b) of raising the half-precast member by applying tension to a second hanging material having its lower end fixed to the half-precast member and attaching its upper end to the support material. This makes it possible to ensure the amount of lift of the half precast member while avoiding the concentration of load at a specific attachment point of the hanging material. Effect of the Invention

[0015] The present invention makes it possible to provide a method for installing a half-precast member that can prevent load concentration at a specific attachment point of a hanging material. [Brief description of the drawings]

[0016] [Figure 1] A diagram showing the top plate 10. [Diagram 2] A diagram showing a method of installing half precast member 1. [Diagram 3] A diagram showing the fixing point of the lower end of the hanging material 5 to the half precast member 1 and the attachment point of the upper end of the hanging material 5 to the support material 4. [Figure 4] A diagram explaining the raising of the half precast member 1. [Diagram 5] 4A to 4C are diagrams for explaining tension setting of the hanging material 5. [Figure 6] Another example of the fixing point of the lower end of the hanging material 5 to the half precast member 1. [Figure 7] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0018] [First embodiment] (1. Half precast member 1 and top plate 10) 1 is a diagram showing a top slab 10 including a half precast member 1 installed by an installation method according to an embodiment of the present invention. The top slab 10 is a plate-like structure provided at the top of a box culvert or water treatment facility, and is bridged between a pair of side walls 20 (supports).

[0019] The top slab 10 is formed by pouring concrete Con on top of the half precast member 1. The half precast member 1 is a concrete precast member 2 to which steel members 3 are attached, and is suspended from support members 4 via suspension members 5.

[0020] The precast slab 2 is a plate-shaped embedded formwork that functions as a formwork when pouring the concrete Con, and is also used as part of the top slab 10 after the concrete Con is poured.

[0021] The steel material 3 is a reinforcing material for reinforcing the precast slab 2 (and the top slab 10), and is provided so as to extend like a beam along the span direction. The span direction is the direction connecting the side walls 20 on both sides of the top slab 10, and corresponds to the left-right direction in Figure 1. The lower part of the steel material 3 is embedded in the concrete of the precast slab 2.

[0022] The shoring material 4 is a member that is installed to extend along the span direction, and is disposed above the half precast member 1. The shoring material 4 is erected between the mounting bases 30 installed on each side wall 20. The shoring material 4 functions as a support for supporting the lower half precast member 1 by suspending it with the hanging members 5. The mounting bases 30 are embedded in the concrete Con of the top slab 10.

[0023] The hanging members 5 are used to suspend the half-precast members 1 from the support materials 4, and are made of rods such as threaded rebars, fully threaded rods, and PC steel rods. Multiple hanging members 5 are placed at intervals in the span direction. The upper end of each hanging member 5 is attached to the support materials 4, and the lower end is fixed to the half-precast members 1.

[0024] (2. Installation method of half precast member 1) Figure 2 is a diagram showing a method for installing the half precast member 1. In this embodiment, first, as shown in Figure 2(a), the half precast member 1 and the support material 4 are arranged. As described above, the half precast member 1 is erected between the two side walls 20, and the support material 4 is erected between the pedestals 30 provided on each side wall 20. After the half precast member 1 is erected, reinforcement of the top slab 10 is also performed.

[0025] Thereafter, the lower end of the hanging material 5 is fixed to the half precast member 1 as shown in FIG. 2(b).

[0026] 3(a) is a diagram showing a fixing point of the lower end of the hanging material 5. In this embodiment, the cross section of the steel material 3 (a cross section perpendicular to the longitudinal direction of the steel material 3) is U-shaped, and its upper part protrudes upward from the precast slab 2.

[0027] The lower end of the hanging material 5 is passed through a hole (not shown) provided in the folded-back portion at the top of the steel material 3. A screw is provided at the lower end of the hanging material 5, and nuts 51 are tightened onto the screws at the lower end of the hanging material 5 on both the upper and lower sides of the folded-back portion, and the folded-back portion is sandwiched between these nuts 51. This fixes the lower end of the hanging material 5 to the steel material 3 of the half precast member 1.

[0028] 3(b) is a diagram showing the upper end of the hanging material 5. The support material 4 in this embodiment has a pair of steel members 41 and an anchor plate 42. In this embodiment, the cross section of the steel members 41 is U-shaped, and the pair of steel members 41 are arranged back-to-back so that a gap is formed between the vertical portions. The anchor plate 42 is arranged between the folded-back portions of the upper portions of the steel members 41 so as to close the gap.

[0029] The hanging material 5 is passed through the gap between the steel materials 41, and its upper end passes through hole 421 in anchor plate 42 and protrudes upward from anchor plate 42. A screw is provided at the upper end of the hanging material 5, and in a later process, the upper end of the hanging material 5 is attached to the support material 4 by tightening nut 53 on the screw above the support material 4 (anchor plate 42). However, at this point, the upper end of the hanging material 5 has not yet been attached.

[0030] As shown in FIG. 3(a), nuts 51 are tightened on the upper and lower sides of the folded-back portion of the upper part of the steel material 3 at the lower end of the hanging material 5, so that when nut 53 is tightened on the upper end of the hanging material 5, the lower end of the hanging material 5 does not rotate together.

[0031] Returning to the description of Fig. 2, in this embodiment, next, tension is applied to the hanging member 5 (second hanging member) at the center of the span to lift up the half precast member 1, as shown in Fig. 2(c).

[0032] In this embodiment, as shown in Fig. 4(a), the nut 53 is tightened toward the support material 4 (anchor plate 42), thereby attaching the upper end of the hanging material 5 to the support material 4 and applying tension to the hanging material 5. As a configuration for preventing the nut 53 from loosening after tightening, it is also preferable to use a spring washer for the nut 53 or to use a double nut for the nut 53.

[0033] The above tension is managed by the torque value when the nut 53 is tightened, and by tightening the nut 53 with a torque wrench, tension is applied to the hanging material 5 to raise the half precast member 1. As a result, as shown diagrammatically in Figure 4(b), the half precast member 1 is raised and deflection during erection is eliminated. The amount of lift δ required in the above process can be calculated, for example, by the following formula (1), and the required torque value F can be calculated, for example, by the following formula (2). δ≧w1+w2-W…(1) F=k·φ·T=k·φ·δ·48E·I / L 3 …(2)

[0034] In formula (1), w1 is the deflection of the half precast member 1 during erection, and w2 is the deflection of the half precast member 1 due to the load (such as the load of concrete Con) during construction of the top plate 10. Also, W is the allowable deflection of the half precast member 1. The values ​​of w1 and w2 can be calculated by cross-sectional calculation or numerical analysis.

[0035] In formula (2), k is the torque coefficient, φ is the diameter of the hanging member 5, T is the tension of the hanging member 5, E is the elastic modulus of the precast slab 2, I is the converted second moment of area of ​​the half precast member 1, and L is the span length between the side walls 20.

[0036] In Fig. 4(b), for the sake of explanation, the deflection of the half precast member 1 is exaggerated. This is also the case in Fig. 5, which will be described later. In addition, as the half precast member 1 is raised, the support material 4 is deflected slightly downward compared to when the support material 4 was erected.

[0037] Returning to the explanation of Fig. 2, in this embodiment, thereafter, as shown in Fig. 2(d), tension is applied to the remaining hanging materials 5 (first hanging materials), and each hanging material 5 is attached to the support material 4 in the same manner as in Fig. 4(a). In this embodiment, tension is applied to each hanging material 5 while managing the tension of each hanging material 5.

[0038] FIG. 5 is a diagram for explaining the introduction of tension into the hanging material 5, and is a schematic diagram showing the half precast member 1, the support material 4, and the hanging material 5.

[0039] As shown in FIG. 5(a), in this embodiment, first, the hanging members 5-4, 5-5 on both sides of the hanging member 5-0 at the center of the span are tensioned, and then, as shown in FIG. 5(b), a tension T0' is applied to these hanging members 5-4, 5-5 and they are attached to the support material 4.

[0040] Next, as shown in Figure 5(c), the hanging members 5-3 and 5-6 on both sides are tensioned, and a tension T1' is applied to the hanging members 5-3 and 5-6 as shown in Figure 5(d) and they are attached to the support material 4. As the half-precast member 1 lifts up, the distance between the half-precast member 1 and the support material 4 shortens, and the tension T0' of the hanging members 5-4 and 5-5 to which tension T0' was previously applied decreases by t1.

[0041] After this, as shown in Figure 5(e), the hanging members 5-2 and 5-7 on both sides are further tensioned, and as shown in Figure 5(f), a tension T2' is applied to the hanging members 5-2 and 5-7 and they are attached to the support material 4, causing the half-precast member 1 to lift up again, reducing the tension T0'-t1 of the hanging members 5-4 and 5-5 and the tension T1' of the hanging members 5-3 and 5-6 by t2. The tension reductions t1 and t2 accumulate in the hanging members 5-4 and 5-5, and the reduction from the initial tension T0' becomes t1+t2.

[0042] In this way, the initial tension T' applied to each of the hanging materials 5-1 to 5-8 is subsequently reduced by applying tension T' to another hanging material 5-1 to 5-8. When the cumulative value Σt of the tension reduction amount t for a certain hanging material 5 reaches the value of the initial tension T', the tension T' acting on that hanging material 5 becomes 0, causing wobble at the attachment point to the support material 4. For this reason, the torque value F' for tightening the nuts 53 of each of the hanging materials 5-1 to 5-8 is set such that the cumulative value Σt for each of the hanging materials 5-1 to 5-8 does not reach the value of the initial tension T' (so that the tension T' of the hanging materials 5-1 to 5-8 does not become 0).

[0043] A numerical analysis that reproduces the actual construction procedure can be used to calculate the tension reduction amounts t1, t2, .... The order in which the hanging members 5-1 to 5-8 are tensioned can be arbitrary, but tensioning can be performed in sequence from the center of the span to the ends of the span, or in the opposite direction, as shown in Figure 5, making it easier to match the analysis conditions and less likely to cause errors. In this case, of the hanging members 5-1 to 5-8, the ones that will have the largest cumulative value Σt of tension reduction amount t are the hanging members 5-4 and 5-5 on both sides of the center of the span, which are tensioned first, or the hanging members 5-1 and 5-8 closest to the ends of the span.

[0044] The above numerical analysis may also be performed under the condition that the initial tension T' applied to each of the hanging materials 5-1 to 5-8 is the same. In this case, by applying tension T' to each of the hanging materials 5-1 to 5-8 using the torque value F' required for the hanging material 5 with the largest cumulative value Σt, it is possible to easily create a state in which the cumulative value Σt of the tension reduction amount t for each of the hanging materials 5-1 to 5-8 does not reach the value of the initial tension T' (a state in which the tension T' of the hanging materials 5-1 to 5-8 does not become 0).

[0045] Incidentally, even in the hanging member 5-0 at the center of the span, the initial tension T decreases due to the lifting of the half precast member 1 when each of the hanging members 5-1 to 5-8 is tensioned. Therefore, it is desirable to confirm that even in the hanging member 5-0 at the center of the span, the initial tension T exceeds the cumulative value Σt of the tension reduction amount t due to the tensioning of the hanging members 5-1 to 5-8.

[0046] In addition, when tension T' is applied to the hanging members 5-1 to 5-8, the half precast member 1 is lifted, so the half precast member 1 will not drop below the point at which tension T is applied to the hanging member 5-0 at the center of the span. Therefore, the amount of lift δ can be managed to be on the safe side.

[0047] After tensioning the hanging material 5 and attaching it to the support material 4 in this manner, the half-precast member 1 is used as a formwork and concrete Con is poured on top of it, thereby constructing the top slab 10 shown in Figure 1.

[0048] In this embodiment, tension is generated in all of the hanging materials 5, including the hanging material 5-0 in the center of the span, so there is no wobble at the attachment points of each hanging material 5 to the support material 4, and it is possible to prevent the load from concentrating on a specific attachment point. As a result, the load during construction acting on the half precast member 1 (such as the load of concrete Con) can be transmitted uniformly to the support material 4 via each hanging material 5.

[0049] As described above, according to this embodiment, when the half precast member 1 is suspended from the support material 4 by the multiple hanging members 5, tension is applied to the hanging member 5-0 to lift the half precast member 1, and then measures are taken to prevent rattling from occurring at the attachment points of the remaining hanging members 5-1 to 5-8 to the support material 4. This makes it possible to ensure the amount of lift of the half precast member 1 while avoiding the concentration of load at a specific attachment point among the attachment points of the hanging members 5-0 to 5-8 to the support material 4. As a result, the load acting on the half precast member 1 during construction can be uniformly transmitted to the support material 4 via the hanging members 5-0 to 5-8.

[0050] Particularly in this embodiment, by performing the above-mentioned tension management as the above-mentioned measure, it is possible to easily and reliably prevent rattling from occurring at the attachment points of the hanging materials 5-1 to 5-8 to the support material 4. Therefore, the construction period required for attaching the hanging materials 5 can be shortened, and the required performance can be easily ensured. Furthermore, since no special materials and equipment are required for attaching the hanging materials 5, the cost required for attachment can also be reduced. Also, in this embodiment, tension management of the hanging materials 5-1 to 5-8 can be easily performed by the torque value F' when the nut 53 is tightened.

[0051] However, the present invention is not limited to the above embodiment. For example, the configuration of the fixing portion of the hanging material 5 to the half precast member 1 is not limited to that described in Fig. 3(a), and may be configured so as not to rotate together with the half precast member 1 when the nut 53 is tightened.

[0052] For example, as shown in Fig. 6(a), a screw hole may be provided in the folded-back portion of the upper part of the steel material 3 of the half precast member 1, and the screw at the lower end of the hanging material 5 may be screwed into the screw hole and nut 51. Also, as shown in Fig. 6(b), an insert 21 may be embedded in the precast plate 2 of the half precast member 1, and the screw at the lower end of the hanging material 5 may be screwed into the screw on the inner surface and nut 51. Furthermore, as shown in Fig. 6(c), a notch 22 may be provided in the precast plate 2 of the half precast member 1, the lower end of the hanging material 5 may be inserted, and a filler 55 such as non-shrink mortar may be filled into the notch 22. It is also possible to use a combination of two or more of these joining methods.

[0053] Furthermore, management of the amount of lift caused by tensioning the hanging material 5-0 in the center of the span is not limited to being based on the torque value F when the nut 53 is tightened, and for example, the distance between the attachment point of the upper end of the hanging material 5 to the support material 4 and the fixing point of the lower end of the hanging material 5 to the half precast member 1 may be measured before and after tension is applied. In this case, tension can be applied to the hanging material 5-0 without using the nut 53, and for example, a turnbuckle may be used as the hanging material 5-0. Furthermore, lifting caused by tensioning the hanging material 5-0 may be omitted in some cases.

[0054] In this embodiment, in the process shown in Fig. 2(d), tension control is used to prevent rattling at the attachment point of the hanging material 5, but the predetermined measures for preventing rattling are not limited to tension control. Another example of the measures will be described below as the second embodiment. The second embodiment will be described in terms of the differences from the first embodiment, and similar points will be denoted by the same reference numerals in the drawings and will not be described again.

[0055] [Second embodiment] In the second embodiment, in the process shown in Figure 2(d) above, as shown in Figure 7(a), a cushioning material 54 is installed between the nut 53 and the support material 4, and the nut 53 is brought into face-to-face contact with the cushioning material 54, thereby preventing rattling at the attachment points of the hanging material 5 (5-1 to 5-8) to the support material 4.

[0056] The buffer material 54 is laid between the underside of the nut 53 at the upper end of the hanging material 5 and the upper surface of the anchoring plate 42, and by manually tightening the nut 53 to the extent that the buffer material 54 is crushed, it is possible to prevent rattling from occurring at the attachment point of the hanging material 5 to the support material 4. As the buffer material 54, gypsum or mortar mixed with water, resin, etc. can be used.

[0057] In this embodiment as well, the same effect as in the first embodiment can be obtained by taking measures to prevent rattling at the attachment points of the hanging materials 5 (5-1 to 5-8) to the support material 4 using the buffer materials 54. Furthermore, in the second embodiment, since almost no tension acts on the hanging materials 5 (5-1 to 5-8), measures to prevent loosening of the nuts 53, such as spring washers, are not required, and the order in which the hanging materials 5 (5-1 to 5-8) are tensioned does not matter.

[0058] Note that elastic bodies such as rubber plates or rubber washers can also be used as the buffer material 54, and there are no particular limitations on the method or material used as long as it can eliminate unevenness between the nuts 53 and the support material 4 (anchor plate 42). When using rubber plates as the buffer material 54, it is also possible to use a common buffer material 54 between multiple hanging materials 5 as shown in Figure 7(b), and construction becomes easier by eliminating unevenness at the mounting points of these hanging materials 5 with the same part. Also, when using rubber plates as the buffer material 54, it is also possible to easily check for unevenness by pulling the rubber plate, etc.

[0059] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to the above examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the technical ideas disclosed in this application, and it is understood that these also naturally belong to the technical scope of the present invention. [Explanation of symbols]

[0060] 1: Half precast members 4: Support materials 5, 5-0~5-8: Hanging material 10:Top version 20: Side wall 51, 53: Nut 54: Cushioning material

Claims

1. A method for installing a half-precast member, comprising: suspending and supporting the half-precast member from a support material using a plurality of hanging members; The method includes a step (a) of attaching an upper end of a first hanging material having a lower end fixed to the half precast member to the support material, A method for installing a half-precast member, characterized in that in the step (a), a specified measure is taken to prevent rattling at the attachment point of the upper end of the first hanging material to the support material.

2. The predetermined treatment is In the step (a), tension is applied to the plurality of first hanging materials, and when the upper end portions of the first hanging materials are attached to the support material, The tension applied to each of the first hanging members is set so that the tension of the first hanging member to which tension has been applied previously does not become 0 when tension is applied to another first hanging member due to the half precast member being lifted.

2. The method for installing a half precast member according to claim 1.

3. A method for installing a half-precast member as described in claim 2, characterized in that in step (a), the upper end of the first hanging material is attached to the support material by tightening a nut toward the support material on the upper side of the support material.

4. The predetermined treatment is In the step (a), when attaching the upper end of the first hanging material to the support material by tightening a nut on the upper end of the first hanging material toward the support material, A buffer material is placed between the nut and the support material.

2. The method for installing a half precast member according to claim 1.

5. The method for installing a half precast member according to claim 4, characterized in that a common cushioning material is provided between a plurality of first hanging members.

6. Prior to the step (a), A method for installing a half-precast member as described in claim 1, characterized in that a step (b) of raising the half-precast member is carried out by applying tension to a second hanging material having a lower end fixed to the half-precast member and attaching an upper end of the second hanging material to the support material.

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