JP2009516108A - Abdomen fixing tool - Google Patents

Abstract

The present invention provides a steel wire fixture for raising a stomach. In an embodiment, the present invention may fix a pre-stress erection steel wire at a position spaced from one end of the erection during a vertical hole (pit) excavation operation for constructing an underground structure. Has an improved structure that can. The fixture prevents an acute angle from being formed in the steel wire, and instead allows the steel wire to extend in an arc shape, thereby ensuring a sufficient moment. The fixture strongly reinforces a portion to which a high compression force and high tension are applied. In another embodiment, the present invention has an improved structure capable of supporting the brace beam and fixing the steel wire in the brace beam at a corner during a vertical hole (pit) drilling operation. . In the corner, the fixture can stably support the brace beam and form a triangular structure that can fix the steel wire and simultaneously apply tension, thereby improving work efficiency. Furthermore, since the fixture has a simple structure, it reduces material consumption and construction costs.
[Selection] Figure 1

Description

  The present invention relates generally to an upset steel wire fixture and, in particular, has a simple structure and secures the steel wire during vertical hole (pit) excavation work for constructing underground structures. The present invention relates to a steel wire fixing tool for a flank that is capable of fixing a steel wire for a pre-stress flank so that it can be reliably reinforced.

  During conventional drilling of pits to build a subway or building basement, the ground is dug to drill the pits at a predetermined depth and with a predetermined area. Vertical piles are installed in the vertical holes (pits).

  After installing a vertical pile in the vertical hole (pit), a part of the vertical hole (pit) is further dug, and then an H beam and a lining plate are installed in the vertical hole (pit).

  After the lining plate is installed in the vertical hole (pit), the construction work of the subway or the basement of the building proceeds through continuous excavation, and repeated installation of brace beams is accompanied by repeated excavation.

  Therefore, in order to construct such a temporary facility, it is necessary to repeatedly calculate both the earth pressure and the load that may be applied to the brace beam in every excavation process, and the brace beam is the maximum soil from which the beam is calculated. It is installed in the vertical hole (pit) so as to effectively withstand both the pressure and the calculated maximum load.

  However, in the above-mentioned conventional design and construction techniques for making underground structures, the brace beams must be densely installed in the vertical holes (pits) with a narrow interval of about 2-3 meters, so an excessive number of Requires brace beams. The brace beams so densely installed prevent the construction material from moving in the vertical hole (pit) undesirably and prevent the construction vehicle from entering the vertical hole (pit). Interfere with work. Further, the densely installed brace beams prevent both formwork and reinforcement work in the construction process of the underground structure, and undesirably form a plurality of holes in the completed underground structure. Remarkably reduces the waterproofness of objects.

  As a technique for forming a temporary facility without using the brace beam while constructing an underground structure, a construction technique for supporting a steel pile using an earth anchor has been proposed. In this technique, an inclined hole is formed in the ground behind each steel pipe, and a steel wire or a steel bar is inserted into the inclined hole. Thereafter, the end portion of the steel wire or the steel bar inserted into the inclined hole is fixed using an epoxy or cement grout through a mechanical method or a chemical method. The fixed steel wire or bar is tensioned to fix the steel pile.

  The temporary installation constructed with earth anchors through the aforementioned techniques can provide sufficient internal space therein, thereby solving the problems experienced in the prior art.

  However, in the technology using the earth anchor, when the technology is used in an active city, the area affected by the construction work may include private land around the construction site. There is a problem in inviting. Another problem with the technology lurks in increasing construction costs.

  In patent document 1, the technique for constructing the temporary installation which uses a truss system is disclosed, without using the brace beam which crosses the center of an excavation part conventionally. The technique can be effectively used when constructing a shallow facility. In order to construct a temporary facility using the above technique, a lattice structure is formed by doublely arranging H beams at positions adjacent to the ground surface. Since the lattice structure is reinforced using vertical beams and diagonal beams, the lattice structure can withstand earth pressure by using a two-layer upper truss.

  The technology using the truss system during the construction of temporary equipment to support the ground overcomes the problems associated with the prior art of using brace beams during the construction of pit excavations and underground structures. Proposed to be. The technique can also be used effectively when a wide structure is installed in the lower part of the vertical hole (pit) and a narrow structure is installed in the upper part of the vertical hole (pit). is there.

  Patent Document 2, Patent Document 3 and Patent Document 4 disclose a technique for reinforcing pretension by applying prestress. Each of the above techniques increases the spacing between the brace beams by installing a belly over a previously installed belly and applying tension to the steel wire. One of the aforementioned techniques uses an additional wake, while the other technique reinforces a conventional H-beam flange.

  The technique described above has the advantage that the spacing between the brace beams can be increased. However, in the above technique, since the steel wire is arranged linearly, a negative moment is generated in the steel wire due to earth pressure, unlike the parabolic distribution of the moment generated in the wake. . In other words, since the distribution of moments generated in the wake is different from the distribution of load induced moments, the length of the reinforced wake is undesirably limited.

  In the above-described conventional technique, since the steel wire is fixed at the end portion of the prestress erection, the curved portion of the steel wire cannot be extended long. Therefore, the steel wire may be cornered (bent), and the cornered portion becomes weak. Furthermore, the arc-shaped curve of the tensile moment, which varies variously at different positions along the steel wire, is shortened and therefore cannot provide sufficient force.

  Furthermore, when a load is applied to the erection, not all portions of the erection where both the compressive force and the tension are applied have sufficient strength. The erection may be structurally fragile and therefore bend easily. Furthermore, the fixed state of the steel wire may be broken.

In the prior art, brace beams or struts are installed in the excavation plane structure so as to fix both the bracing wall and the corners around the bracing wall. Furthermore, since various steel materials are used at the corner to withstand earth pressure, a lot of materials are wasted and the construction cost is increased. The space in the excavation plane structure is reduced by the steel material, and therefore the work efficiency after fixing the prestressed steel wire is lowered.
Korean Utility Model Registration No. 20-258949 Korean Patent No. 10-188465 Korean utility model registration number 20-247053 Japanese Patent No. 837994

  Therefore, the present invention has been made with the problems that occur in the prior art in mind, and the object of the present invention is during vertical hole (pit) excavation work for constructing underground structures, It has a simple structure, can fix pre-stressed steel wires, and can be installed with long steel wires because of the simple structure of the device, so that it can sufficiently withstand earth pressure. It is possible to provide an abdominal steel wire fixture in which the high compressive force and high tension parts are highly reinforced.

  In order to achieve the above object, an aspect of the present invention provides a steel wire fixture for raising an abdomen including the following. A fixed body having a cross beam shape, wherein the fixed body is integrated with the end portion of the pre-stress erection at the first end, and a connection hole is formed in the fixed body, and the end of the erection steel wire And a leading block that is provided at a second end portion of the fixed body and fixes an end portion of the steel wire erected.

  In another aspect, the present invention provides a flank steel wire fixture comprising: A transverse beam integrated with a prestress ridge, a compressed beam obliquely attached to one end of the transverse beam, the compressed beam having at least one corner brace beam obliquely attached to the compressed beam, and the transverse beam And an end of a triangle formed by an oblique cut beam installed obliquely to connect the end of the compression beam and the end of the compression beam, and the compression beam, the oblique cut beam, and the transverse beam. The first and second leading blocks, wherein the first and second leading blocks are fixed at a distance from each other and can separately apply tension to the steel wire passing through the triangle. The first block characterized by

  A fixing tool according to an embodiment of the present invention fixes a pre-stress erection steel wire at a position spaced from one end of the erection during vertical hole (pit) excavation work for constructing an underground structure. With an improved structure that can be. The fixture prevents an acute angle from being formed in the steel wire, and instead allows the steel wire to extend in an arc shape, thereby ensuring a sufficient moment. Further, the fixture strongly reinforces a portion where high compression force and high tension are applied.

  A fixture according to another embodiment of the present invention supports a brace beam in the brace beam at a corner during a vertical hole (pit) excavation work for constructing an underground structure, and fixes a steel wire to tension. With an improved structure that can give In the corner, the fixture can stably support the brace beam, fix the steel wire, and at the same time form a triangular structure capable of giving tension, so that the vertical hole (pit) excavation Improve work efficiency during work. Furthermore, since the fixture has a simple structure, it reduces material consumption and construction costs. Furthermore, in order to prevent close placement of the brace beams at the corners and to prevent the space from being reduced, the fixing device withstands earth pressure using the tension of the steel wire, so that the work space is expanded and the space is increased. Improve usage efficiency.

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

[Embodiment 1]
Referring to FIGS. 1 to 3, the steel wire fixture for raising a stomach according to the first embodiment of the present invention is integrally formed in front of the brazed wall 10, and is attached to the steel wire 22. A pre-stress erection 20 having a tension for applying tension, and a first end portion of which is bolted to the end of the erection 20 and has a connection hole 202, and the steel wire 22 is connected to the connection hole 202 A fixed body 200 that is allowed to pass through, and a leading block 400, which is provided at a second end of the stationary body 200 and that fixes the end of the steel wire 22 inserted into the leading block 400 And a copper wire support 300 that protrudes from the front surface of the fixed body 200 and supports the steel wire 22 at an angle.

  The fixed body 200 described in detail is constructed in the form of a beam that is integrated with and extends from the end of the erection 20 and preferably uses a conventional H beam.

  When the H beam is used as the fixed body 200, it is necessary to reinforce the flange of the beam having the connection hole 202, so the reinforcing plate 206 is attached to the inner surface of the flange by welding or bolting.

  Further, the stopper 250 protrudes from the front surface of the fixed body 200 in order to ensure reinforcement against the shear stress generated in the fixed body 200 during the fixing process of the steel wire 22.

  The stopper 250 may be formed in any of various shapes as long as it can provide reinforcement against shearing force. For example, the stopper 250 may be configured as a horizontal structure that is parallel to the fixed body 200 and provides a wide reinforcing surface on the front surface of the fixed body 200.

  Furthermore, in order to ensure reinforcement of the inner surface of the fixed body 200, at least one stiffener 260 is integrally provided on the inner surface by welding. Since the end plate 270 is provided by welding at the first end portion of the fixed body 200 combined with the end portion of the erection 20, the fixed body 200 can be effectively combined and coupled with the erection 20. .

  Further, a guide plate 220 having a predetermined curvature is integrated on the inner surface of the fixed body 200 to guide the insertion of the steel wire 22 into the fixed body 200.

  The steel wire support portion 300 is attached to the front surface of the fixed body 200 at a first end portion thereof using a bolt, and the second end portion can support the steel wire 22 and is in contact with the steel wire 22. As such, the second end may be configured as a single unit that is rounded. Alternatively, the steel wire support portion 300 may be configured as a plurality of bodies including a first body integrated with the fixed body 200 and a second body for supporting the steel wire 22.

  More preferably, the second end portion of the steel wire support portion 300 prevents the steel wire 22 from being entangled or twisted, while forming a slit end portion capable of supporting a plurality of steel wires 22. It is comprised so that the steel wire contact part of a 2nd end part may be divided | segmented into several parts.

  A box-shaped protective cap 450 having an open end is preferably provided on the fixture. The protective cap 450 is combined with the second end of the fixed body 200 and covers both the leading block 400 and the fixed steel wire 22. Accordingly, the protective cap 450 protects the steel wire fixing leading block 400 from external impacts.

  The fixture having the above-described structure according to the first embodiment of the present invention functions as follows.

  In the fixture according to the first embodiment of the present invention, the first end of the fixed body 200 is formed so that the fixed body 200 extends in the horizontal direction from the end of the belly 20. Combined with the end. Therefore, since the said fixing tool can fix the edge part of the steel wire 22 of the said prestress erection 20 to the said fixing body 200 instead of the edge part of the said erection 20, the said stationary steel wire 22 is an arc. A shape curve can be maintained.

  Thus, the fixture prevents the steel wire 22 from forming an acute angle and increases the length of the steel wire 22, thereby increasing the prestress moment of the steel wire 22.

  After the fixed body 200 is combined with the end of the erection 20, the steel wire 22 is guided over the rounded second end of the steel wire support 300 and passes through it.

  Thereafter, the steel wire 22 guided by the steel wire support part 300 enters the fixed body 200 through the connection hole and contacts the guide plate 220 having a predetermined curvature. The steel wire 22 enters the leading block 400 and is tensioned by a separate tension device before the steel wire 22 is fixed to the leading block 400.

  Thereafter, the second end of the fixed body 200 is covered with the protective cap 450 to lock the steel wire 22 fixed to the leading block 400, so that the leading block 400 is protected from external impacts. Is possible.

  In the present invention, the stiffener 260, the guide plate 220, and the stopper 250 of the fixed body 200 can be incorporated into the single body by welding. However, when designing the H beam, the stiffener 260 of the fixed body 200 The guide plate 220 and the stopper 250 can be designed as a single structure, and may be integrally formed as a single structure during the H-beam forming process.

  Since the steel wire 22 fixed to the leading block 400 applies tension to both the erection 20 and the fixed body 200, both the erection 20 and the fixed body 200 sufficiently withstand earth pressure. be able to.

  In other words, the present invention fixes the steel wire 22 of the erection 20 to a position beyond the end of the erection 20, thereby preventing an acute angle from being formed in the steel wire 22, and A sufficient tensile moment is given to 22.

  4 and 5 show another shape (plate shape or H beam shape) of the stopper 250 of the present invention. In the drawing, when a stopper 250 having one of various shapes is provided on the front surface of the fixed body 200 so as to protrude from the front surface, the stopper 250 may be the fixed body regardless of the shape. Illustrates that the desired durability of 200 can be ensured and that the fixing body 200 can withstand the shear stress generated therein when the steel wire 22 is fixed.

[Embodiment 2]
Hereinafter, a steel wire fixture for raising a stomach according to a second embodiment of the present invention will be described with reference to FIGS. The fixture includes a cross beam 610 coupled to the end of the flank 520 for supporting a brace wall 510. The compression beam 620 is obliquely connected to one end of the transverse beam 610 and is integrated with at least one brace beam 550. Since the oblique beam 630 is obliquely connected to both one end of the compression beam 620 and one end of the transverse beam 610, the beams 610 and 620 are connected to each other. A connecting hole 632 is formed in the oblique beam 630 at a position adjacent to the flank 520 to allow the steel wire 522 of the flank 520 to enter the hole 632. The first and second leading blocks 710 and 720 include the compression beam 620, the oblique beam 630, and the first and second leading blocks 710 and 720 so that the steel wires 522 are separately fixed and tensioned. Separately provided in a triangle formed by the cross beam 610.

  The transverse beam 610, the compression beam 620, and the oblique beam 630 described in detail are connected to each other to form a triangular support structure. Each of the transverse beam 610, the compression beam 620, and the oblique beam 630 includes at least one stiffener 650 in which the H beam having a flange and a web is integrated with the inner surface of the H beam by welding for reinforcement. May be used together.

  The transverse beam 610, the compression beam 620, and the diagonally cut beam 630 connect the brace beam 550 to the erection 520 and are stable to the compressive force applied by both the brace beam 550 and the erection 520. Form a triangular support structure that is resistant to damage.

  The ends of both the compressed beam 620 and the oblique beam 630 are preferably connected at right angles to each other, but it should be understood that the compressed beam 620 and the oblique beam 630 are at an acute angle or an obtuse angle with each other. Connected.

  The compression beam 620 is connected to the brace beam 550 so as to transmit the compression force thereof, but the transverse beam 610 is integrally connected to the erection 520. Therefore, the reinforcing plate 810 is preferably provided at a corner joint between the transverse beam 610 and the compression beam 620.

  Further, a preloading jack (not shown) having a cylinder actuator and transmitting a compressive force is preferably provided at the center of the brace beam 550. Since the triangular fixture is provided at the end of the flank 520 at each corner, the fixture allows the flank to withstand its earth pressure using the tension of the steel wire. The brace beam 550 is preferably connected to the compression beam 620 of the opposite fixture so that the compression force exerted by the preceding loading jack can be transmitted to the bracing wall.

  Further, since the end plate 614 is combined with the first end of the transverse beam 610 which is preferably connected to the end of the erection 520 by welding, the transverse beam 610 is connected to the erection 520 more securely and reliably. Is possible.

  A guide plate 900 having a predetermined curvature is integrated with the inner surface of the oblique beam 630 and guides the entrance of the steel wire 522 to the oblique beam 630. The guide plate 900 has a structure that is slid along the inner surface of the oblique beam 630 by a lifting jack 950.

  The lifting jack 950 preferably incorporates a screw jack. When a screw jack is used as the lifting jack 950, the first end of the lifting jack 950 is integrated with one end of the guide plate 900, so that the guide plate 900 can be interlocked with the lifting jack 950. The second end of the lifting jack 950 is attached to the mounting plate 955 using a nut unit 952 such that the second end is moved through the mounting plate during rotation.

  Therefore, the lifting jack 950 controls the upper and lower widths of the guide plate 900 and finely controls the angle of the steel wire 522.

  The functions of the first and second head blocks 710 and 720 may be designed as follows. The first leading block 710 disposed at the upper position has a fixing function, and the second leading block 720 disposed at the lower position has a tension function. In that case, the first leading block 710 of another fixing tool provided at the opposite end of the erection 520 has a tension function, whereas the second leading block 720 has a fixing function.

  More preferably, the shear key 615 extends from the lower part of the cross beam 610 so that the shear key 615 interferes with the end of the erection 520 along a horizontal line. Since the end portion of the anti-raising 520 that receives the compressive force is located in the direction opposite to the direction in which the force is transmitted from the compressed beam 620, the compressive force is generated by the force transmitted from the compressed beam 620. Is offset.

  In order to support the shear key 615, the connecting member 1000 is preferably combined with the erection 520 such that the linking member 1000 is located between the erection 520 and the fixture. The connection member 1000 is integrated with the shear key 615 of the fixture using a bolt.

  Since the connecting member 1000 is preferably provided with an upper shearing key 1010 protruding forward, the force transmitted from the upper shearing key 1010 cancels the compressive force transmitted to the end of the cross beam 610 and is offset. To do.

  Further, the first and second wire guide members 715 and 725 having a tube shape are preferably disposed on the inner side of the reinforcing plate 810 at a position between the first and second leading blocks 710 and 720 and the oblique beam 630. The steel wire 522 is separately guided to the first and second leading blocks 710 and 720.

  The fixture having the above-described structure according to the second embodiment of the present invention functions as follows.

  During the vertical hole (pit) excavation work for constructing the underground structure, the fixture according to the present invention is connected to it at each corner, and the first and second leading blocks 710 and 720 are used to The brace beam 550 that fixes the end of the steel wire 522 and applies tension is provided.

  In the above state, the end of the steel wire 522 enters the connecting member and is guided to the first and second leading blocks 710 and 720 by the first and second steel wire guide members 715 and 725.

  Thereafter, the first leading block 710 fixes the end of the steel wire 522, while the second leading block 720 applies tension to the end of the steel wire 522. The lifting jack 950 is then operated to curve the steel wire 522 as desired, thus controlling the upper and lower widths of the guide plate 900.

  In other words, when the second end of the lifting jack 950 bolted to the mounting plate is rotated in one direction, the guide plate 900 moves upward or downward depending on the direction in which the lifting jack 950 is rotated. Therefore, the upper and lower widths of the guide plate 900 can be controlled, and the curvature of the steel wire 522 entering the guide plate 900 is changed.

  In the fixture, the brace beam 550 disposed at a corner is connected to the compression beam 620 having the triangular support structure. Further, the steel wire 522 of the erection 520 is tensioned and fixed by the first and second leading blocks 710 and 720. Therefore, the fixture performs the function of connecting the brace beam 550 and the function of applying tension to the steel wire 522 and fixing it at one place.

  Therefore, each corner of the vertical hole (pit) has a simple structure, and the work space is expanded to provide an empty space except for the area occupied by the fixture. Furthermore, the present invention can variably perform an operation of fixing and applying tension to the steel wire 522 which is erected, and an operation of applying tension and fixing the steel wire 522 disposed on the opposite side of the erection 520. Can be managed.

  At each corner of the vertical hole (pit), the brace beam 550 is fixed and connected to the compression beam 620, so that the compressive force transmitted from the brace beam 550 passes through the compression beam 620, and the diagonal beam It is transmitted to both the cutting beam 630 and the transverse beam 610. After that, the compressive force is transmitted to the erection 520 through the connecting member 1000, so that the erection 520 can effectively withstand earth pressure.

  In the above state, the shear key 615 of the fixture and the upper shear key 1010 of the connecting member 1000 are connected to the end of the connecting member 1000 and the end of the cross beam 610, respectively, and thus the members interfere with each other. To do. Therefore, since the direction of the compressive force transmitted from the brace beam 550 is opposite to the direction of the earth pressure transmitted from the bellow 520, the compressive force offsets the earth pressure.

  The fixture according to the second embodiment of the present invention is preferably used together with the connecting member at a corner during a vertical hole (pit) excavation operation, but it should be understood that the fixture does not have the connecting member. It is also possible to use it.

FIG. 1 is a plan view illustrating a steel wire fixture for raising a stomach according to a first embodiment of the present invention. FIG. 2 is a plan sectional view illustrating an important part of the present invention. FIG. 3 is a front view illustrating a state in which the copper wire support is used in the fixture of the present invention. FIG. 4 is a front view illustrating stoppers having various shapes used in a fixture according to another embodiment of the present invention. FIG. 5 is a front view illustrating stoppers having various shapes used in a fixture according to another embodiment of the present invention. FIG. 6 is a plan view illustrating a steel wire fixture for raising a stomach according to a second embodiment of the present invention. FIG. 7 is an enlarged plan view illustrating a portion “A” of FIG. 6. FIG. 8 is a plan sectional view illustrating an important part of FIG. FIG. 9 is a plan view illustrating a state in which the wire guide member is used in the fixture of FIG. FIG. 10 is a diagram illustrating the function of the lifting jack used in the fixture of FIG.

Claims (14)

  A fixed body having a cross beam shape, wherein the fixed body is integrated with the end portion of the pre-stress erection at the first end, and a connection hole is formed in the fixed body, and the end of the erection steel wire A fixed body characterized in that a portion can pass through the connecting hole, and a leading block that is provided at a second end of the fixed body and fixes the end of the steel wire of the abdomen A steel wire fixture for raising the stomach.   The steel wire fixture according to claim 1, further comprising a stopper protruding from the front surface of the fixed body so as to increase a shearing force of the fixed body.   The steel wire fixture for erection according to claim 1, further comprising a guide plate having a predetermined curvature so as to guide insertion of the steel wire into the fixed body and integrated with an inner surface of the fixed body.   The steel wire fixture for erection according to claim 1, further comprising: A protective cap that is combined with the second end of the fixed body and covers the leading block.   The steel wire fixture for an abdomen according to claim 1, further comprising at least one stiffener integrally provided on an inner surface of the fixed body.   The steel wire fixture for erection according to claim 1, further comprising a copper wire support portion that protrudes from the front surface of the fixed body and guides the steel wire obliquely.   A transverse beam integrated with a prestress ridge, a compressed beam obliquely attached to one end of the transverse beam, the compressed beam having at least one corner brace beam obliquely attached to the compressed beam, and the transverse beam And an end of a triangle formed by an oblique cut beam installed obliquely to connect the end of the compression beam and the end of the compression beam, and the compression beam, the oblique cut beam, and the transverse beam. The first and second leading blocks, wherein the first and second leading blocks are fixed at a distance from each other and can separately apply tension to the steel wire passing through the triangle. A steel wire fixture for abdomen including a head block characterized by being attached.   A steel wire fixture for raising a stomach according to claim 7, wherein each of the transverse beam, the compression beam, and the oblique cutting beam has an H beam having a flange and a web so as to increase the compression force of the web. An abdominal steel wire fixture for use with at least one stiffener integrally combined with the beam.   8. A steel wire fixture for erection according to claim 7, further comprising a guide plate having a predetermined curvature and provided inside the oblique beam so as to guide insertion of the steel wire into the oblique beam. .   The steel wire fixture for erection according to claim 7, further comprising a reinforcing plate integrated with both the inner surface of the transverse beam and the inner surface of the compression beam.   First and second wires having a tube shape provided at a position between the first and second leading blocks and the oblique beam, and thus guiding the steel wire separately to the first and second leading blocks. The steel wire fixture for erection according to claim 7, further comprising a guide member.   10. The urging steel wire fixture according to claim 9, further comprising an elevating jack, wherein the elevating jack is integrally combined with the guide plate so that the elevating jack is movable in the oblique beam.   8. A steel key for erection according to claim 7, further comprising a shear key extending from the lower part of the transverse beam so as to interfere with the end of the erection on a horizontal line. Fixture.   A connecting member provided between the cross beam and the bellows so as to support the shearing key, wherein the upper shearing key protrudes forward from the end of the connecting member and is integrated with the bellows 14. The erected steel wire fixture according to claim 13, further comprising a connecting member, wherein the upper shearing key interferes with an end of the cross beam in a direction in which a compressive force is transmitted.

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