Clamps for suspended scaffolding and support structures for suspended scaffolding

Abstract

This invention provides a clamp for suspended scaffolding made of concrete girders and a support structure for suspended scaffolding that can be installed safely and quickly without the use of post-construction anchors, eliminating the risk of falling or damaging PC steel materials. [Solution] In a clamp for suspended scaffolding installed on the flange of a concrete girder, a jack 3 is installed in the center below the flange G1a and capable of pushing up the concrete girder (main girder G1), and a pair of left and right clamp bodies 2a, 2b are slidably connected to both sides of the jack 3. The clamp bodies 2a, 2b are equipped with an arm portion 20a (20b) that hooks onto the inclined surface of the flange G1a, and a connecting plate portion 21a (21b) joined to the lower part of the arm portion 20a (20b). Multiple bolt holes h1a to h6b are drilled in the connecting plate portion 21a (21b) at predetermined intervals, and the left and right clamp bodies 2a, 2b are bolted together by connecting the connecting plate portions to each other using the bolt holes h1a to h6b, thereby allowing the length to be freely adjusted according to the width of the concrete girder (main girder G1).

Description

[Technical Field]

[0001] The present invention relates to a clamp for a suspended scaffolding and a support structure for a suspended scaffolding, and more specifically, to a clamp for a suspended scaffolding installed on a concrete girder and a support structure for a suspended scaffolding provided with the clamp for a suspended scaffolding. [Background Art]

[0002] Conventionally, a suspending base that supports a suspended scaffolding used for work such as inspection, repair and reinforcement of bridges made of concrete girders such as PCT girder bridges has been fixed by drilling a hole in the side surface of the concrete girder with a drilling machine and driving a post-installed anchor such as a metal expansion anchor into the hole. Then, by obtaining reaction force from the side surface of the concrete girder fixed by the post-installed anchor, a working floor assembled from single pipes and scaffolding planks is suspended and supported by chains or the like.

[0003] However, in the conventional support structure for a suspended scaffolding in which post-installed anchors are driven into the side surface of such a concrete girder, thorough construction management such as concrete drilling position and drilling depth is required for driving and fixing the post-installed anchors. That is, there has been a problem that insufficient construction management may lead to serious accidents such as falling accidents of the suspended scaffolding.

[0004] In addition, when the concrete girder is a PC girder (prestressed concrete girder), there is a risk of damaging the PC steel material during concrete drilling. Even when prestress is not introduced into the concrete girder, there is a problem that drilling may interfere with internal reinforcing bars and cause damage during drilling.

[0005] As a support structure for suspended scaffolding that does not use post-installed anchors, Patent Document 1 discloses a support structure for suspended scaffolding of a concrete girder bridge, in which a pressing device is attached to the end of the horizontal member to press against the web portion of the girder or beam in the axial direction of the horizontal member in order to restrain the horizontal member and restrain the position of the horizontal member by the reaction force of the girder or beam acting in the axial direction of the horizontal member (see Claim 1 of the claims, paragraphs

[0030] to

[0071] of the specification, and Figures 1 to 13 of the drawings of Patent Document 1).

[0006] Furthermore, as a clamp for a suspended scaffolding of a concrete girder that grips the flange portion of the concrete girder, Patent Document 2 discloses a suspended scaffolding support fitting comprising a horizontal member positioned substantially horizontally and substantially perpendicular to the axial direction of the concrete girder, and two locking members joined to the horizontal member and raised upward along both sides of the concrete girder, which are locked into an enlarged section of the cross-section where the cross-section of the girder is widened in the width direction near the lower edge, wherein the upper part of the locking members is locked so as to rest on the inclined upper side of the enlarged section, and both locking members are joined in such a way that changes in the joining angle with the horizontal member are constrained, and at least one of them is movable in the axial direction of the horizontal member, and is fixed in a position corresponding to the width dimension of the cross-section of the girder (see Claim 1 of the claims, paragraphs

[0020] to

[0044] of the specification, and Figures 1 to 7 of the drawings of Patent Document 2).

[0007] Furthermore, support brackets for PC girder suspended scaffolding, such as "Movie Clamp" manufactured by Nissho Sangyo Co., Ltd. and "Tsurubei" (registered trademark) manufactured by SMC Tech Co., Ltd., are commercially available. These commercially available PC girder suspended scaffolding support brackets have a structure that obtains the reaction force to support the weight of the suspended scaffolding from the flange portion of the concrete girder by gripping the flange portion of the concrete girder from both sides with the support bracket.

[0008] However, the pressing device for the support structure of the suspended scaffolding described in Patent Document 1, the suspended scaffolding support fitting described in Patent Document 2, and commercially available suspended scaffolding support fittings for PC girders are heavy, weighing 28.0 kgf or more, which presents a problem in that it is difficult to easily and safely install suspended scaffolding in a short time under concrete girder bridges where it is difficult to install lifting facilities. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2018-48450 [Patent Document 2] Japanese Patent Publication No. 2012-122266 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Therefore, the present invention was devised in view of the aforementioned problems, and its objective is to provide a clamp for suspended scaffolding for concrete girders and a support structure for suspended scaffolding that can be installed safely and quickly without the use of post-installed anchors, without the risk of falling or damaging PC steel materials. [Means for solving the problem]

[0011] The clamp for suspended scaffolding according to the first invention is a clamp for suspended scaffolding installed on the flange of a concrete girder, comprising a jack installed in the center below the flange and capable of pushing up the concrete girder, and a pair of left and right clamp bodies slidably connected to both sides of the jack, the clamp body comprising an arm portion that is hooked onto the inclined surface of the flange, and a connecting plate portion joined to the lower part of the arm portion, the connecting plate portion having a plurality of bolt holes drilled at predetermined intervals, and the pair of left and right clamp bodies are connected to each other via the bolt holes, the connecting plate portions are connected to each other superimposed Because they are bolted together, the length can be freely adjusted according to the width of the concrete girder. At the same time, the jack pushes up the central part below the flange of the concrete girder, causing the pair of left and right clamp bodies to be pulled towards the concrete girder via the arms and tightened.It is characterized by the following:

[0012] The clamp for suspended scaffolding according to the second invention is characterized in that, in the first invention, the jack is a pantograph jack in which a plurality of arm plates are pin-joined, and the pin-joined connection points move up and down to freely push up the concrete girder.

[0013] The clamp for suspended scaffolding according to the third invention is characterized in that, in the second invention, an elongated hole is formed in the joining plate portion, and the pantograph jack is fixed by being bolted to the elongated hole so as to be slidable.

[0014] The clamp for suspended scaffolding according to the fourth invention is a clamp for suspended scaffolding installed on the flange of a concrete girder, comprising a jack installed in the center below the flange and capable of pushing up the concrete girder, and a pair of left and right clamp bodies slidably connected to both sides of the jack, wherein the clamp body comprises an arm portion that is hooked onto the inclined surface of the flange and a joining plate portion joined to the lower part of the arm portion, the joining plate portion has a plurality of bolt holes drilled at predetermined intervals, and the pair of left and right clamp bodies are bolted together by overlapping the joining plate portions through the bolt holes, thereby being configured to be able to adjust the length according to the width of the concrete girder, the jack is a pantograph jack in which a plurality of arm plates are pin-connected, and the pin-connected connection points move up and down to be able to push up the concrete girder, an elongated hole is formed in the joining plate portion, and the pantograph jack is fixed by being bolted to the elongated hole so as to be able to slide, and a suspension ring fitting for attaching suspended scaffolding is provided on the pin at the lower end of the pantograph jack. The 5 In the first invention, the clamp for suspended scaffolding has the following features: The tip of the arm is pivotally supported relative to the arm so as to be swingable The device is characterized by having a oscillating member that contacts the inclined surface of the flange to obtain a reaction force.

[0015] The 6 The clamp for suspended scaffolding according to the invention is characterized in that, in the first invention, at least one of the left and right clamp bodies is configured such that the arm portion and the connecting plate portion can swing freely relative to each other.

[0016] The 7 The support structure for a suspended scaffold according to the invention is a support structure for a suspended scaffold that supports a suspended scaffold installed under a bridge made of concrete girders, and claims 1 to 6 The suspended scaffolding clamp described in any of the above is installed on the concrete girder, and the suspended scaffolding, on which scaffolding boards are laid out, is suspended and supported by the suspended scaffolding clamp. [Effects of the Invention]

[0017] First Invention ~ 7 According to the invention, the clamp for suspended scaffolding can be made light enough to be lifted by one person, and can be attached to the flange of a concrete girder by hand without using a lifting machine. Furthermore, the first invention to the second invention7 According to the invention, the jack can generate a jacking force to jack up the concrete girder, and can also generate a clamping force for drawing a pair of left and right clamp bodies toward the concrete girder side for clamping. Therefore, without using post-installed anchors that would damage prestressed concrete steel, the flange of the concrete girder can be reliably embraced and gripped from both sides by the pair of left and right clamp bodies, and the suspended scaffolding can be suspended and supported by being jacked up with the jack, so the suspended scaffolding can be safely installed in a short time without risk of damaging the PC steel material.

[0018] In particular, according to the third invention, the slide bolt of the pantograph jack can be slid against the elongated hole formed in the joining plate portion to be fixed by bolt joining. Therefore, the length adjustment of the pantograph jack can be completed only by sliding and tightening the slide bolt, and the jacking operation of the jack can be completed in a short time.

[0019] In particular, the 5 According to the invention, a swingable rocking member that abuts against the inclined surface of the flange to obtain a reaction force is provided, so even if the inclined angle of the slope on the upper part of the flange of the concrete girder differs due to manufacturing errors, angle adjustment can be performed to achieve accurate support. In addition, according to the 5 According to the invention, even slight size differences of concrete girders can be handled with one type of clamp for suspended scaffolding, and the manufacturing cost can be reduced.

[0020] In particular, according to the 6 According to the invention, it is no longer necessary to perform on-site length adjustment work by tightening bolts according to the width of the concrete girder for each clamp for suspended scaffolding, and the length of the joining plate portion can be adjusted according to the width of the concrete girder before being carried into the site. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] [Figure 1] Figure 1 is a front view of the clamp for suspended scaffolding according to the first embodiment of the present invention, as viewed in the bridge axis direction X in a state where the clamp is mounted on a concrete girder. [Figure 2] Figure 2 is a front view showing the clamp body of the same clamp for suspended scaffolding. [Figure 3] Figure 3 is a front view showing the jack of the clamp for the suspended scaffolding shown above. [Figure 4] Figure 4 shows the procedure for attaching the clamp for the suspended scaffolding shown above. [Figure 5] Figure 5 shows the bolt connection positions at the connecting plate section for each width of the main girder in the clamp for the suspended scaffolding described above, where (a) is when the width of the main girder is 700 mm, (b) is when the width of the main girder is 650 mm, (c) is when the width of the main girder is 600 mm, (d) is when the width of the main girder is 550 mm, and (e) is when the width of the main girder is 500 mm. [Figure 6] Figure 6 is a front view of the suspension scaffolding clamp according to the second embodiment of the present invention, as seen in the bridge axis direction X, with the clamp attached to the concrete girder. [Figure 7] Figure 7 is a front view showing the clamp body of the suspended scaffolding clamp shown above, where (a) shows the first clamp body on the left side when viewed in the bridge axis direction X, and (b) shows the second clamp body on the right side when viewed in the bridge axis direction X. [Figure 8] Figure 8 is a front view mainly showing the jack of the clamp for the suspended scaffolding shown above. [Figure 9] Figure 9 shows the procedure for attaching the above-mentioned clamp for suspended scaffolding to the main beam. [Modes for carrying out the invention]

[0022] Hereinafter, one embodiment of the clamp for suspended scaffolding and the support structure for suspended scaffolding of concrete girders according to the present invention will be described in detail with reference to the drawings.

[0023] <Clamps for suspended scaffolding on concrete girders and support structure for suspended scaffolding> [First Embodiment] Using Figures 1 to 5, the clamp 1 for suspended scaffolding of a concrete girder (hereinafter also simply referred to as "clamp 1 for suspended scaffolding") and the support structure of the suspended scaffolding according to the first embodiment of the present invention will be described. As an example of the concrete girder bridge to be reinforced, a PCT girder bridge (T-type prestressed concrete girder bridge) equipped with a post-tensioned T-type prestressed concrete girder (main girder G1) will be described.

[0024] Figure 1 is a front view of the suspension scaffolding clamp 1 according to the first embodiment, as seen in the bridge axis direction X, with the clamp attached to the main girder G1. Figure 2 is a front view showing the clamp body 2a (2b) of the suspension scaffolding clamp 1, where (a) shows the first clamp body 2a on the left side as seen in the bridge axis direction X, and (b) shows the second clamp body 2b on the right side as seen in the bridge axis direction X. Figure 3 is a front view showing the jack 3 alone. The symbols X, Y, and Z in the figures represent the bridge axis direction X, the direction perpendicular to the bridge axis Y, and the vertical direction Z, respectively.

[0025] As shown in Figure 1, the suspended scaffolding clamp 1 comprises a pair of symmetrical clamp bodies 2a and 2b that grip the flange of the main girder G1, which is a concrete girder, and a jack 3 that is installed directly below the flange G1a of the main girder G1 between these clamp bodies 2a and 2b to connect them. Furthermore, as a support structure for the suspended scaffolding equipped with the suspended scaffolding clamp 1, a chain 5 is connected to the jack 3 of the suspended scaffolding clamp 1 via a suspension ring fitting 4. In other words, the suspended scaffolding clamp 1 suspends and supports the suspended scaffolding (not shown), which consists of scaffolding planks laid out, by this chain 5.

[0026] (Clamp body) As shown in Figures 1 and 2, the clamp body 2a (2b) comprises an arm portion 20a (20b) made of steel material such as angle steel, and a joining plate portion 21a (21b) made of steel material such as steel plate that is joined perpendicularly to the lower end of the arm portion 20a (20b).

[0027] Furthermore, a pivoting member 22a (22b) is provided at the upper end (tip) of the arm portion 20a (20b), pivotally supported on the arm portion 20a (20b). This pivoting member 22a (22b) follows and contacts the inclined surface G1b (haunch) of the flange G1a of the main girder G1, which may be of different sizes, and has the function of obtaining a reaction force from the inclined surface G1b against the weight of the suspended scaffolding. Therefore, even if the size of the main girder G1 is different or the inclination angle differs due to manufacturing tolerances, the pivoting member 22a (22b) can be angle-adjustable and attached to and supported by the main girder G1 according to the inclination angle of the inclined surface G1b of the main girder G1. Thus, even with slight differences in the size of the main girder G1, one type of suspended scaffolding clamp 1 can be used.

[0028] The joining plate portion 21a (21b) is a plate for joining the jack 3, and for overlapping and bolting together the first clamp body 2a on the left and the second clamp body 2b on the right. As shown in Figure 2, the joining plate portion 21a (21b) has a plurality of independent bolt holes h1a (h1b) to h6a (h6b) for joining the first clamp body 2a on the left and the second clamp body 2b on the right.

[0029] These bolt holes h1a(h1b) to h6a(h6b) are provided in a set of six at predetermined intervals (for example, 50 mm pitch) from the base end side that connects to the clamp body 2a(2b). Note that there is a 150 mm center-to-center distance between bolt holes h4a(h4b) and h5a(h5b). As described later, when using the clamp 1 for suspended scaffolding on main girders with a width of 500 mm to 700 mm, the bolt hole between bolt hole h4a(h4b) and bolt hole h5a(h5b) can be covered without being used.

[0030] As shown in Figure 1, the first clamp body 2a on the left and the second clamp body 2b on the right are bolted together at two of the six bolt holes h1a (h1b) to h6a (h6b), with the connecting plate portion 21a and connecting plate portion 21b being bolted together. This connection is then attached to the flange G1a of the main girder G1.

[0031] Furthermore, the connecting plate portion 21a (21b) has elongated holes h7a (h7b) formed therein for adjusting and securing the slide bolts 38 of the jack 3. These elongated holes h7a (h7b) are for adjusting the length to which the jack 3 pushes up according to the size of the main girder G1.

[0032] (jack) As shown in Figure 3, Jack 3 is a pantograph jack with a diamond-shaped link mechanism in which four strip-shaped steel arm plates 30-33 are pin-jointed with two rivet pins 36 and two slide bolts 38, and the pin-jointed connection points move up and down to freely push up the main girder G1. Thus, Jack 3 is a link mechanism in which four strip-shaped arm plates 30-33 are pin-jointed to each other, and the slide bolts 38 are slidable along the aforementioned elongated holes h7a (h7b).

[0033] Therefore, by bolting the slide bolt 38 to any position in the elongated holes h7a (h7b) indicated by the dashed-dotted line, which are overhead lines, the arm plates 30-33 of the jack 3 extend vertically while maintaining a symmetrical rhombus shape, allowing them to be adjusted to any height. As a result, the jack 3 can generate an upward thrust force by pushing up the lower surface of the flange G1a of the main girder G1 in the direction of the arrow in Figure 3 using the base plate 39 joined to the upper rivet pin 36.

[0034] Furthermore, the jack according to the present invention may also be a pantograph jack with a worm gear structure that has a worm gear nut and a core bolt, and by rotating the worm gear nut, the core bolt is rotated, which extends vertically and generates an upward thrusting force.

[0035] (Suspension ring fittings and chain) The suspension ring fitting 4 is an annular fitting formed by welding the ends of steel bars together to create an elongated hole when viewed from the side. The chain 5 is a member consisting of continuously connected elliptical or circular metal rings, and is used to suspend and support a suspended scaffolding (not shown). A turnbuckle with adjustable length may be inserted between the suspension ring fitting 4 and the jack 3, or between the suspension ring fitting 4 and the chain 5, as this makes it easier to adjust the height of the suspended scaffolding.

[0036] <Installation Procedure> Next, the procedure for attaching the suspension scaffolding clamp 1 to the main girder G1 according to this embodiment will be briefly explained using Figures 4 and 5. Figure 4(a) shows the procedure for attaching the clamp body 2a(2b) of the suspension scaffolding clamp 1 to the main girder G1, and Figure 4(b) shows the procedure for attaching the jack 3 to the clamp body 2a(2b) of the suspension scaffolding clamp 1 and pushing up the main girder G1 with the jack 3.

[0037] As shown in Figure 4(a), the procedure for attaching the suspension scaffolding clamp 1 to the main girder G1 involves overlapping the first clamp body 2a on the left and the second clamp body 2b on the right and bolting them together. At this time, two bolt holes are selected from the six bolt holes h1a(h1b) to h6a(h6b) according to the width of the main girder G1. In the illustrated configuration, as will be described later, the width of the main girder G1 is 600 mm, so a bolt is inserted into one of the bolt holes (h2a(h6b) in the illustrated configuration) (h2a(h6b)) and joined together.

[0038] In the illustrated configuration, the case where the width of the main girder G1 is 600 mm is shown as an example. In this case, the first clamp body 2a on the left and the second clamp body 2b on the right are overlapped and joined by inserting a bolt into h2a (h6b). Then, the second clamp body 2b is swung around the bolt inserted into h2a (h6b), and the swinging member 22b of the second clamp body 2b is brought into contact with the inclined surface G1b (haunch) of the main girder G1 and secured. After that, a bolt is inserted into the remaining h6a (h2b) to bolt it in place.

[0039] Then, as shown in Figure 4(b), the slide bolt 38 of the jack 3 is slid along the elongated hole h7a (h7b) to extend the arm plates 30-33 vertically, pressing the base plate 39 against the lower surface of the flange G1a of the main girder G1, and fixing it in place by bolting it with the slide bolt 38 at the position of the elongated hole h7a (h7b).

[0040] <Bolt connection location> Figure 5 shows the bolt connection positions at the connecting plate section 21a (21b) for each width of the main girder G1. Figure 5(a) shows the case when the main girder G1 is 700 mm wide, and Figure 5(b) shows the case when the main girder G1 is 650 mm wide. Furthermore, Figure 5(c) shows the case when the main girder G1 is 600 mm wide, Figure 5(d) shows the case when the main girder G1 is 550 mm wide, and Figure 5(e) shows the case when the main girder G1 is 500 mm wide.

[0041] For the main girder G1, when the width of the main girder G1 is 700 mm, the bolt connection positions at the connecting plate sections 21a (21b) are as shown in Figure 5(a), by inserting bolts into the 4th bolt hole h4a (h6b) and the 6th bolt hole h6a (h4b) from the base end.

[0042] Furthermore, if the width of the main girder G1 is 650 mm, the joint is made by inserting bolts into the third bolt hole h3a (h6b) and the sixth bolt hole h6a (h3b) from the base side, as shown in Figure 5(b).

[0043] When the width of the main girder G1 is 600 mm, the joint is made by inserting bolts into the second bolt hole h2a (h6b) and the sixth bolt hole h6a (h2b) from the base side, as shown in Figure 5(c).

[0044] When the width of the main girder G1 is 550 mm, the joint is made by inserting bolts into the first bolt hole h1a (h6b) and the sixth bolt hole h6a (h1b) from the base side, as shown in Figure 5(d).

[0045] Then, if the width of the main girder G1 is 500 mm, the joint is made by inserting bolts into the first bolt hole h1a (h5b) and the fifth bolt hole h5a (h1b) from the base side, as shown in Figure 5(e).

[0046] As described above, the suspended scaffolding clamp 1 has a simple and basic structure, and each clamp has a lifting capacity of 19 kgf (≒186.3 N) or less, which is a weight that can be lifted by one person. For this reason, it can be attached to the flange of the main girder G1 by hand without using lifting equipment such as chain blocks or electric hoists.

[0047] Furthermore, as shown in Figure 4, the suspended scaffolding clamp 1 allows the slide bolt 38 of the jack 3 to slide along the elongated hole h7a (h7b), extending the arm plates 30-33 vertically and pressing the base plate 39 against the lower surface of the flange G1a of the main girder G1. This allows the suspended scaffolding clamp 1 to generate an upward force that pushes the main girder G1 upward with the jack 3. Moreover, as the jack 3 pushes upward, the pair of left and right clamp bodies 2a and 2b generate a tightening force that pulls the main girder G1 towards it via the oscillating members 22a (22b).

[0048] Therefore, with the suspended scaffolding clamp 1, the flange of the main girder G1, which is a concrete girder, can be securely held and gripped from both sides by a pair of clamp bodies 2a and 2b, without using post-installed anchors that may damage the PC steel material. The suspended scaffolding can then be pushed up by the jack 3 and supported via the chain 5. For this reason, the suspended scaffolding clamp 1 can be installed safely and quickly without the risk of damaging the PC steel material.

[0049] Furthermore, as shown in Figures 5(a) to 5(e), the suspended scaffolding clamp 1 can accommodate slight size differences in the main girder G1 as long as the width is within the range of 500mm to 700mm. In addition, the inclination angle of the flange top surface can be accommodated from 46.2° to 57.4°. Therefore, even with slight size differences in the main girder G1, one type of suspended scaffolding clamp 1 can be used, which can reduce manufacturing costs.

[0050] Furthermore, in the suspended scaffolding clamp 1, a swinging member 22a (22b) is provided at the tip of the upper part of the arm 20a (20b) on the main girder G1 side. Therefore, even if the slope of the upper part of the flange of the main girder G1 has a different inclination angle due to manufacturing tolerances, the angle can be adjusted by the swinging member 22a (22b) to provide accurate support.

[0051] [Second Embodiment] Next, using Figures 6 to 9, a concrete girder suspension scaffolding clamp 1' (hereinafter also simply referred to as "suspension scaffolding clamp 1'") according to the second embodiment of the present invention will be described. The concrete girder bridge to be reinforced is assumed to be a PCT girder bridge equipped with the aforementioned post-tensioned T-type prestressed concrete girder (main girder G1).

[0052] Figure 6 is a front view of the suspension scaffolding clamp 1' according to the second embodiment, as seen in the bridge axis direction X, with the clamp attached to the main girder G1. Figure 7 is a front view showing the clamp body 2a (2b) of the suspension scaffolding clamp 1', where (a) shows the first clamp body 2a on the left side as seen in the bridge axis direction X, and (b) shows the second clamp body 2b on the right side as seen in the bridge axis direction X. Figure 8 is a front view mainly showing the jack 3'. The symbols X, Y, and Z in the figures represent the bridge axis direction X, the direction perpendicular to the bridge axis Y, and the vertical direction Z, respectively.

[0053] As shown in Figure 6, the suspended scaffolding clamp 1' comprises a pair of left and right clamp bodies 2a', 2b' that grip the flange of the main girder G1, which is a concrete girder, and a jack 3' that is installed directly below the flange G1a of the main girder G1 between these clamp bodies 2a', 2b' to connect them. Furthermore, as a support structure for the suspended scaffolding equipped with the suspended scaffolding clamp 1', a chain 5 is connected to the jack 3' of the suspended scaffolding clamp 1' via a suspension ring fitting 4'. In other words, the suspended scaffolding clamp 1' suspends and supports the suspended scaffolding (not shown) with scaffolding boards laid out by this chain 5.

[0054] (Clamp body) As shown in Figures 6 and 7, the clamp body 2a'(2b') includes an arm portion 20a'(20b') made of steel materials such as angle steel that are combined to hook onto the inclined surface G1b of the flange G1a, and a joining plate portion 21a'(21b') made of steel material such as a steel plate that is joined perpendicularly to the lower end of the arm portion 20a'(20b').

[0055] This arm portion 20a'(20b') consists of a straight portion 24a'(24b') extending in the vertical direction and a protruding portion 23a'(23b') that extends laterally (horizontally) from the upper end (tip) of the straight portion 24a'(24b' and is attached perpendicular to the straight portion 24a'(24b').

[0056] Furthermore, a pivoting member 22a'(22b') is provided at the tip of the protruding portion 23a'(23b'), pivotally supported on the protruding portion 23a'(23b'). This pivoting member 22a'(22b') follows and contacts the inclined surface G1b (haunch) of the flange G1a of the main girder G1, which may be of different sizes, and has the function of obtaining a reaction force from the inclined surface G1b against the weight of the suspended scaffolding. Therefore, even if the size of the main girder G1 is different or the inclination angle differs due to manufacturing tolerances, the pivoting member 22a'(22b') can be angle-adjustable and attached to and supported by the main girder G1 according to the inclination angle of the inclined surface G1b of the main girder G1. Thus, even with slight differences in the size of the main girder G1, one type of suspended scaffolding clamp 1' can be used.

[0057] The joining plate portion 21a'(21b') is a plate for joining the jack 3', and for overlapping and bolting the first clamp body 2a' on the left and the second clamp body 2b' on the right. As shown in Figure 7, the joining plate portion 21a'(21b') has a plurality of independent bolt holes h1a'(h1b') to h6a'(h6b') drilled into it for joining the first clamp body 2a' on the left and the second clamp body 2b' on the right.

[0058] These bolt holes h1a'(h1b') to h6a'(h6b') are provided in a set of six at predetermined intervals (for example, 50 mm pitch) from the base end side that connects to the clamp body 2a'(2b'). However, there is a 150 mm center-to-center distance between bolt holes h4a'(h4b') and bolt holes h5a'(h5b'). This is because, similar to the suspended scaffolding clamp 1 of the first embodiment, when used on main girders with a width of 500 mm to 700 mm, which is the assumed range of application for the suspended scaffolding clamp 1', the bolt hole between bolt hole h4a'(h4b') and bolt hole h5a'(h5b') can be covered without being used.

[0059] As shown in Figure 6, the first clamp body 2a' on the left and the second clamp body 2b' on the right are bolted together using two of the six bolt holes h1a'(h1b') to h6a'(h6b') at the joint plate portion 21a' and the joint plate portion 21b', respectively, and are attached to the flange G1a of the main girder G1.

[0060] Furthermore, the connecting plate portion 21a'(21b') has elongated holes h7a'(h7b') formed therein for adjusting and securing the slide bolts 38' of the jack 3'. These elongated holes h7a'(h7b') are for adjusting the length to which the jack 3' pushes up according to the size of the main girder G1.

[0061] Unlike the clamp body 2a according to the first embodiment, the first clamp body 2a' according to this embodiment is configured such that the lower end of the straight portion 24a' of the arm portion 20a' and the connecting plate portion 21a' are bolted together via a swinging plate 25a', allowing the arm portion 20a' and the connecting plate portion 21a' to swing freely relative to each other. Therefore, it is no longer necessary to perform the work of tightening bolts to adjust the length according to the width of the main girder G1 on-site for each suspended scaffolding clamp 1'. In short, before transporting the clamp 1' directly beneath the main girder G1 on-site, all the bolts of the connecting plate portion 21a' and the connecting plate portion 21b' can be bolted together according to the width of the main girder G1 in a location where the length adjustment work can be easily performed without bending down, and the suspended scaffolding clamp 1' can be transported directly beneath the main girder G1 with the length adjustment completed and then hooked onto the flange G1a of the main girder G1.

[0062] (jack) As shown in Figure 8, jack 3' is a pantograph jack consisting of a double rhombic link mechanism in which six strip-shaped steel arm plates 30'~35' are pin-jointed with multiple connecting bolts 37' and two sliding bolts 38', and the pin-jointed connection points move up and down to freely push up the main girder G1. Thus, jack 3' is a link mechanism in which six strip-shaped arm plates 30'~35' are pin-jointed to each other, and the sliding bolts 38' are slidable along the aforementioned elongated holes h7a' (h7b').

[0063] Therefore, by bolting the slide bolt 38' to any position in the elongated hole h7a' (h7b'), the arm plates 30'~35' of the jack 3 extend vertically while maintaining a symmetrical, connected rhombus shape, allowing for adjustment to any desired height (see also Figure 6). As a result, the jack 3' can generate an upward thrust force by pushing up the lower surface of the flange G1a of the main girder G1 in the direction of the arrow in Figure 8 using the base plate 39' joined to the upper connecting bolt 37'.

[0064] (Suspension ring fittings and chain) The suspension ring fitting 4' is a commercially available U-shaped fitting made by joining the upper end of a U-shaped steel material with a bolt to form a ring. The chain 5 is a member in which elliptical or circular metal rings are continuously connected, and is the aforementioned chain 5 that suspends and supports the suspended scaffolding (not shown) (see Figure 6). A turnbuckle with adjustable length may be inserted between the suspension ring fitting 4' and the jack 3', or between the suspension ring fitting 4' and the chain 5, as this makes it easier to adjust the height of the suspended scaffolding.

[0065] <Installation Procedure> Next, the procedure for attaching the suspension scaffolding clamp 1' to the main girder G1 according to the second embodiment will be briefly explained using Figures 6, 7, and 9. Figure 9 is a diagram showing the procedure for attaching the suspension scaffolding clamp 1' to the main girder G1.

[0066] As shown in Figures 7 and 9, the procedure for attaching the suspension scaffolding clamp 1' to the main girder G1 involves overlapping the first clamp body 2a' on the left and the second clamp body 2b' on the right, and bolting the joining plate portions 21a'(21b') together. At this time, two bolt holes are selected from the six bolt holes h1a'(h1b') to h6a'(h6b') of the first clamp body 2a' and the second clamp body 2b', according to the width of the main girder G1. In the illustrated configuration, the width of the main girder G1 is 650 mm, so bolts are inserted into h3a'(h6b') and h6a'(h3b') respectively to join them.

[0067] In the illustrated configuration, the first clamp body 2a' on the left and the second clamp body 2b' on the right are superimposed and joined by inserting a bolt into h3a' (h6b'). Then, the first clamp body 2a' is swung around a bolt inserted through the swing plate 25a', causing the swing member 22a' of the first clamp body 2a' to contact and hook onto the inclined surface G1b (haunch) of the main girder G1. After that, bolts are inserted into the straight section 24a' and the joining plate section 21a' to bolt the straight section 24a' and the joining plate section 21a' together.

[0068] Then, as shown in Figures 6 and 9, the slide bolt 38' of the jack 3' is slid along the elongated hole h7a' (h7b') to extend the arm plates 30'~35' (see Figure 8) vertically, pressing the base plate 39' against the lower surface of the flange G1a of the main girder G1, and the slide bolt 38' is bolted in place at the position of the elongated hole h7a' (h7b') to fix it in place.

[0069] As described above, the suspended scaffolding clamp 1' has a simple and basic structure, and each clamp can lift a weight of 19 kgf (≒186.3 N) or less, which can be done by one person. Therefore, it can be attached to the flange of the main girder G1 by hand without using lifting equipment such as chain blocks or electric hoists.

[0070] Furthermore, as shown in Figures 6 and 9, the suspended scaffolding clamp 1' allows the slide bolt 38' of the jack 3' to slide along the elongated hole h7a' (h7b'), extending the arm plates 30' to 35' vertically, and pressing the base plate 39' against the lower surface of the flange G1a of the main girder G1. This allows the suspended scaffolding clamp 1' to generate an upward force that pushes the main girder G1 upward with the jack 3'. Moreover, as the jack 3' pushes upward, the pair of left and right clamp bodies 2a', 2b' can generate a tightening force that pulls the main girder G1 towards it via the oscillating members 22a' (22b').

[0071] Therefore, with the suspended scaffolding clamp 1', the flange of the main girder G1, which is a concrete girder, can be securely gripped from both sides by a pair of clamp bodies 2a' and 2b' without using post-installed anchors that may damage the PC steel material, and the suspended scaffolding can be pushed up by the jack 3' and supported via the chain 5 (see Figure 6). For this reason, the suspended scaffolding clamp 1' can be installed safely and quickly without the risk of damaging the PC steel material.

[0072] Furthermore, similar to the aforementioned suspended scaffolding clamp 1, the suspended scaffolding clamp 1' can accommodate slight size differences as long as the width of the main girder G1 is within the range of 500mm to 700mm. In addition, the suspended scaffolding clamp 1' can accommodate inclination angles of the flange top surface from 46.2° to 57.4°. Therefore, even with slight size differences in the main girder G1, one type of suspended scaffolding clamp 1' can be used, which can reduce manufacturing costs.

[0073] Furthermore, the clamp 1' for suspended scaffolding is provided with a swinging member 22a'(22b') on the arm portion 20a'(20b') that can swing according to the inclination angle of the inclined surface G1b. Therefore, even if the inclination angle of the inclined surface G1b of the flange G1a of the main girder G1 differs due to manufacturing tolerances, the angle can be adjusted by the swinging member 22a'(22b') to accurately suspend and support it.

[0074] Furthermore, with the suspended scaffolding clamp 1', it becomes unnecessary to perform the work of tightening bolts to adjust the length according to the width of the main girder G1 on-site for each suspended scaffolding clamp 1'. Specifically, with the suspended scaffolding clamp 1', before transporting it to the site directly beneath the main girder G1, all the bolts of the connecting plate section 21a' and connecting plate section 21b' can be bolted together according to the width of the main girder G1 in a location where the length adjustment work can be easily performed without bending down. With the length adjustment completed, the suspended scaffolding clamp 1' can be transported directly beneath the main girder G1 and hooked onto the flange G1a of the main girder G1.

[0075] The clamps 1,1' for suspended scaffolding and the support structure for suspended scaffolding equipped with these clamps 1,1' have been described in detail above according to the first and second embodiments of the present invention. However, the dimensions and materials of the embodiments described above or illustrated are merely examples of embodiments that have been materialized in carrying out the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these. [Explanation of Symbols]

[0076] 1,1': Clamp for suspended scaffolding 2a, 2a': First clamp body 2b, 2b': Second clamp body 20a,20b,20a',20b': Arm 21a, 21b, 21a', 21b': Joint plate section 22a, 22b, 22a', 22b': Oscillating members 23a', 23b': Projection part (arm part) 24a', 24b': Straight line part (arm part) 25a': Oscillating plate h1a~h6a, h1b~h6b, h1a'~h6a', h1b'~h6b': Bolt holes h7a, h7b, h7a', h7b': elongated pores 3,3': Jack 30~33, 30'~35': Arm plate 36: Rivet pin 37': Connecting bolts 38,38': Slide bolt 39,39': Base plate 4,4': Hanging ring fittings 5: Chain G1: Main girder (concrete girder) G1a: Flange G1b: Inclined surface (haunch)

Claims

1. A clamp for suspended scaffolding that is installed on the flange of a concrete girder, The system includes a jack installed in the center below the flange and capable of pushing up the concrete girder, and a pair of left and right clamp bodies slidably connected to both sides of the jack. The clamp body comprises an arm portion that is hooked onto the inclined surface of the flange, and a connecting plate portion joined to the lower part of the arm portion. Multiple bolt holes are drilled in the aforementioned connecting plate portion at predetermined intervals. The left and right clamp bodies are bolted together by overlapping the connecting plate portions through the bolt holes, thereby allowing their length to be adjusted according to the width of the concrete girder. The jack pushes up against the central part below the flange of the concrete girder, causing the pair of left and right clamp bodies to be pulled towards the concrete girder via their arms and tightened. A clamp for suspended scaffolding, featuring the following characteristics.

2. The jack is a pantograph jack in which multiple arm plates are pin-connected, and the pin-connected joints move up and down to freely push up the concrete girder. A clamp for suspended scaffolding according to claim 1, characterized by the above.

3. The connecting plate portion has an elongated hole, and the pantograph jack is fixed by being bolted to the elongated hole so as to be slidable. A clamp for suspended scaffolding according to claim 2, characterized by the above.

4. A clamp for suspended scaffolding that is installed on the flange of a concrete girder, The system includes a jack installed in the center below the flange and capable of pushing up the concrete girder, and a pair of left and right clamp bodies slidably connected to both sides of the jack. The clamp body comprises an arm portion that is hooked onto the inclined surface of the flange, and a connecting plate portion joined to the lower part of the arm portion. Multiple bolt holes are drilled in the aforementioned connecting plate portion at predetermined intervals. The left and right clamp bodies are bolted together by overlapping the connecting plate portions through the bolt holes, thereby allowing their length to be freely adjusted according to the width of the concrete girder. The aforementioned jack is a pantograph jack in which multiple arm plates are pin-connected, and the pin-connected joints move up and down to freely push up the concrete girder. The connecting plate portion has an elongated hole, and the pantograph jack is fixed by being bolted to the elongated hole so as to be slidable. The lower end pin of the pantograph jack is provided with a suspension ring fitting for attaching a suspended scaffolding. A clamp for suspended scaffolding, featuring the following characteristics.

5. The clamp body is provided with a pivoting member that is pivotably supported at the tip of the arm and contacts the inclined surface of the flange to obtain a reaction force. A clamp for suspended scaffolding according to claim 1, characterized by the above.

6. At least one of the pair of left and right clamp bodies is configured such that the arm portion and the connecting plate portion can swing relative to each other. A clamp for suspended scaffolding according to claim 1, characterized by the above.

7. A support structure for a suspended scaffolding that supports a suspended scaffolding installed beneath a bridge made of concrete girders, A clamp for suspended scaffolding according to any one of claims 1 to 6 is installed on the concrete girder, The suspended scaffolding, with scaffolding planks laid out, is suspended and supported by the aforementioned clamps for suspended scaffolding. A support structure for suspended scaffolding characterized by the following.

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