Positioning device and method for steel box girder array steel bar reinforcement

Abstract

The present invention discloses a positioning device and method for array-type steel bar reinforcement of steel box girders. The positioning device includes a magnetic positioning connection chain and a transverse positioning piece. The magnetic positioning connection chain includes a magnetic positioning bolt and a longitudinal connecting rod; the number of magnetic positioning bolts and longitudinal connecting rods is matched according to the length of the crack, and two adjacent magnetic positioning bolts are connected by a longitudinal connecting rod, and the connection between the magnetic positioning bolt and the longitudinal connecting rod is an anchor connection; each magnetic positioning bolt is adsorbed and installed on the crack at intervals by magnetic attraction. A transverse positioning piece is provided relative to the position of each magnetic positioning bolt; each transverse positioning piece is arranged across the crack, and the middle part of the transverse positioning piece can be locked with the magnetic positioning bolt at the corresponding position by a nut, and at the same time, two annular positioning structures are symmetrically provided at both ends of the transverse positioning piece. Therefore, the present invention improves the reinforcement efficiency while positioning the drilling.

Description

Technical Field

[0001] The present invention relates to the field of fatigue crack reinforcement of steel box girder bridges, and more particularly to a positioning device and method for array-type steel bar reinforcement of steel box girders. Background Art

[0002] Steel box girders are a common form of long-span bridge construction, known for their light weight, high strength, and ease of construction. However, under complex operating environments and long-term alternating loads, steel box girders can suffer from serious defects, particularly fatigue cracking. Because the top plate of the steel box girder directly bears vehicle wheel loads, the U-ribs welded to the underside of the top plate are often the most susceptible to fatigue cracking. Fatigue issues in steel box girder bridges have become prominent in recent years, and the occurrence of fatigue cracks has a significant impact on the safety and durability of the structure.

[0003] Chinese patent application CN202111166093.1 discloses a steel bar reinforcement structure and its construction method for repairing fatigue cracks in U-rib butt welds. As a new reinforcement method, it has outstanding reinforcement effects among existing fatigue crack repair and reinforcement methods, while avoiding the introduction of new fatigue-prone details such as opening hand holes.

[0004] However, maintenance of steel box girders requires entry into the interior of the girder, which has a narrow working environment, a very limited operating range, and a poor working environment, making it unsuitable for extended periods of time. The development trend of fatigue cracks in steel box girders is difficult to predict, resulting in cracks of varying lengths and directions, making it difficult for technicians to locate them. Furthermore, under the dual influence of harsh working conditions and changing work requirements, it is difficult to maintain the accuracy of drilling positioning, making it difficult for technicians to improve their efficiency. These factors have greatly restricted the development of fatigue crack repair and reinforcement work in steel box girders.

[0005] Therefore, in response to current technical problems, a positioning device is needed that can meet positioning requirements, while taking into account portability, accuracy, and variability while drilling positioning, greatly reducing the difficulty of reinforcement operations and improving reinforcement efficiency. Summary of the Invention

[0006] The patent of this invention provides a positioning device and method for array steel bar reinforcement of steel box girders, which can achieve variable overall length and angle of the device, have high precision, be detachable, recyclable, and replaceable, and is simple to use, lightweight and portable, thereby improving reinforcement efficiency.

[0007] In order to achieve the above technical objectives, the present invention will adopt the following technical solutions:

[0008] A positioning device for array steel bar reinforcement of a steel box girder, used for locating cracks on the steel box girder, comprising a magnetic positioning connecting chain and a transverse positioning piece, wherein:

[0009] The magnetic positioning connection chain is arranged along the direction of extension of the crack length and includes magnetic positioning bolts and longitudinal connecting rods; the number of magnetic positioning bolts is M, and the number of longitudinal connecting rods is M-1, where M ≥ 1; the number of magnetic positioning bolts and longitudinal connecting rods is matched according to the length of the crack, and two adjacent magnetic positioning bolts are connected by a longitudinal connecting rod, and the connection between the magnetic positioning bolts and the longitudinal connecting rod is an anchor connection; each magnetic positioning bolt is magnetically adsorbed and installed on the crack one by one at intervals;

[0010] The described transverse positioning piece is provided with a transverse positioning piece relative to the position of each magnetic positioning bolt; each transverse positioning piece is arranged across the crack, and the middle part of the transverse positioning piece can be locked with the magnetic positioning bolt at the corresponding position through a nut, and at the same time, two annular positioning structures for locating the drilling position are symmetrically provided at both ends of the transverse positioning piece.

[0011] Preferably, the magnetic positioning bolt includes a positioning bolt and an annular magnet installed at the bottom of the positioning bolt.

[0012] Preferably, the positioning bolt includes a bolt body; the bolt body is divided into an upper and lower part, and the lower part of the bolt body is provided with two staggered position-limiting mounting grooves, while the upper part of the bolt body is provided with a threaded rod-shaped portion that cooperates with the nut; the two position-limiting mounting grooves correspond to the first and second position-limiting mounting grooves;

[0013] One end of the longitudinal connecting rod is provided with a first clamping tube structure that can be embedded in the first limiting installation groove, and the other end is provided with a second clamping tube structure that can be embedded in the second limiting installation groove; both the first and second clamping tube structures can rotate around the magnetic positioning bolt at the installation position.

[0014] Preferably, the transverse positioning piece comprises a U-shaped piece; both side arms of the U-shaped piece extend outward to form connecting end ears to respectively connect with the two annular positioning structures, and a reserved hole is provided at the middle position of the closed end of the U-shaped piece;

[0015] The reserved hole of the U-shaped piece is sleeved on the periphery of the threaded rod-shaped portion and is locked with a corresponding positioning bolt through a nut.

[0016] Preferably, the lower portion of the bolt body is provided with an annular groove structure, and the annular groove structure has two raised baffles provided on both sides of the locating bolt, and the two raised baffles are respectively referred to as the first and second raised baffles;

[0017] Two position-limiting mounting grooves that are staggered in height are formed in the annular groove structure by the first and second raised baffles.

[0018] Preferably, the upper surface of the first raised baffle is directly connected to the upper groove wall of the annular groove structure as a whole, and there is a gap between the lower surface of the first raised baffle and the lower groove wall of the annular groove structure suitable for embedding the second clamping tube structure;

[0019] The lower surface of the second raised baffle is directly connected to the lower groove wall of the annular groove structure as a whole, and there is a gap between the upper surface of the second raised baffle and the upper groove wall of the annular groove structure suitable for embedding the first clamping tube structure.

[0020] Preferably, the magnetic positioning bolt is provided with a central through hole along the axis.

[0021] Preferably, the diameter of the annular positioning structure is the same as the diameter of the drill hole to be positioned.

[0022] Preferably, the longitudinal connecting rod is made of plastic POM polyacetaldehyde material.

[0023] Another technical object of the present invention is to provide a positioning method for steel box girder array steel bar reinforcement, which is implemented based on the above-mentioned positioning device for steel box girder array steel bar reinforcement and includes the following steps:

[0024] Step A: Determine the crack length and prepare the required parts

[0025] Determine the matching number of positioning bolts, annular magnets, longitudinal connecting rods, transverse positioning pieces, and nuts based on the length of the crack to be reinforced;

[0026] Step B: Assemble the magnetic positioning connection chain

[0027] First, the annular magnets are glued one by one to the bottom of the corresponding positioning bolts to form magnetic positioning bolts; then the magnetic positioning bolts are sequentially connected with the longitudinal connecting rods to form a chain-like structure to obtain a magnetic positioning connection chain;

[0028] Step C: Linear positioning

[0029] According to the direction of the crack to be reinforced, adjust the linear shape of the magnetic positioning connection chain to match the crack to be reinforced to complete the preliminary positioning; then observe the relative position of the magnetic positioning bolt and the crack to be reinforced through the central through-hole set on the magnetic positioning bolt, and continuously adjust it until the center of the magnetic positioning bolt can coincide with the crack to be reinforced;

[0030] Step D: Install the lateral positioning piece

[0031] After the linear positioning is completed, install the transverse positioning pieces and rotate them to adjust their relationship with the overall linear shape of the magnetic positioning connection chain. The transverse positioning pieces installed at the beginning and end of the magnetic positioning connection chain are perpendicular to the overall linear shape of the magnetic positioning connection chain, and the remaining transverse positioning pieces are kept near the angle bisector of the overall linear angle of the magnetic positioning connection chain. After the position adjustment is completed, screw in the nuts and tighten them.

[0032] Step E: Drilling Positioning

[0033] Use the transverse positioning piece to mark the surface of the steel box girder to complete the positioning;

[0034] Step F: Device disassembly

[0035] Loosen the nut, remove the lateral positioning piece, and finally remove the magnetic positioning connecting chain.

[0036] Based on the above technical objectives, the present invention has the following advantages over the prior art:

[0037] 1. In the magnetic positioning connection chain, the connection between the magnetic positioning bolts and the longitudinal connecting rods is an anchor connection. Therefore, by matching an appropriate number of magnetic positioning bolts, longitudinal connecting rods and transverse positioning pieces, the present invention can achieve drilling positioning of cracks of any length.

[0038] 2. The connection between the magnetic positioning bolt and the longitudinal connecting rod is an anchor connection, which can achieve rotation within a certain range, so that the present invention can achieve drilling positioning of arc-shaped cracks.

[0039] 3. Detachable structure design, easy to carry.

[0040] 4. The rods are made of plastic POM polyacetaldehyde material, which is light in weight, suitable in hardness and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a parts diagram of the positioning device for array-type steel bar reinforcement of a steel box girder according to the present invention;

[0042] Figure 2 yes Figure 1 Schematic diagram of the structure of the positioning bolt, in which: (a) is a schematic diagram of the three-dimensional structure of the positioning bolt, and (b) is a cross-sectional view of the positioning bolt;

[0043] Figure 3 yes Figure 1 Schematic diagram of the structure of the longitudinal connecting rod, in which: (a) is a schematic diagram of the three-dimensional structure of the longitudinal connecting rod, (b) is a front view of the longitudinal connecting rod, and (c) is a top view of the longitudinal connecting rod;

[0044] Figure 4 yes Figure 1 Schematic diagram of the structure of the horizontal positioning piece, in which: (a) is a top view of the horizontal positioning piece, (b) is a front view of the horizontal positioning piece, and (c) is a schematic diagram of the three-dimensional structure of the horizontal positioning piece;

[0045] Figure 5 This is a schematic diagram of the assembly process of a positioning device for array steel bar reinforcement of a steel box girder;

[0046] Figure 6 This is a schematic structural diagram of a positioning device for array steel bar reinforcement of a steel box girder for the first type of crack;

[0047] Figure 7 This is a schematic structural diagram of a positioning device for array steel bar reinforcement of a steel box girder for the second type of crack;

[0048] Figure 8 This is a schematic diagram of the application of the steel box girder array steel bar reinforcement method described in the present invention on a real bridge;

[0049] In the accompanying drawings: a positioning bolt 1; a cylindrical structure 1-1; a baffle 1-2; a nut 2; a longitudinal connecting rod 3; a clamping tube structure 3-1; a transverse positioning piece 4; an annular positioning structure 4-1; a U-shaped piece 4-2; a reserved hole 4-3; and an annular magnet 5. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way serves as any limitation on the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention. Unless otherwise specified, the relative arrangement of components and steps, expressions and numerical values described in these embodiments do not limit the scope of the present invention. Technologies, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods and equipment should be considered part of the specification. In all examples shown and discussed here, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values.

[0051] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations).

[0052] like Figure 1 、 6 -7, the positioning device for steel box beam array steel bar reinforcement of the present invention includes a magnetic positioning connection chain and a transverse positioning piece 4, wherein: the magnetic positioning connection chain is arranged along the extension direction of the crack length, including magnetic positioning bolts and longitudinal connecting rods 3; the number of magnetic positioning bolts is M, the number of longitudinal connecting rods 3 is M-1, M ≥ 1. The number of magnetic positioning bolts and longitudinal connecting rods 3 is matched according to the length of the crack, Figure 6 In the embodiment, the number of magnetic positioning bolts is 5, and the number of longitudinal connecting rods 3 is 4; Figure 7 In the embodiment, there are three magnetic positioning bolts and two longitudinal connecting rods 3. Two adjacent magnetic positioning bolts are connected by a longitudinal connecting rod 3, and the connection between the magnetic positioning bolts and the longitudinal connecting rod 3 is an anchor connection, so that the longitudinal connecting rod 3 can rotate around the magnetic positioning bolts, so that the magnetic positioning connection chain formed in series can be suitable for different crack lengths and different crack line shapes; each magnetic positioning bolt is magnetically adsorbed and installed on the crack one by one at intervals; the transverse positioning piece is provided with a transverse positioning piece 4 relative to the position of each magnetic positioning bolt; each transverse positioning piece 4 is arranged across the crack, and the middle part of the transverse positioning piece 4 can be locked with the magnetic positioning bolt at the corresponding position by a nut 2. At the same time, two annular positioning structures 4-1 for locating the drilling position are symmetrically provided at both ends of the transverse positioning piece 4.

[0053] The magnetic positioning bolt comprises a positioning bolt 1 and an annular magnet 5 installed at the bottom of the positioning bolt.

[0054] like Figure 2As shown, the positioning bolt 1 is made of plastic POM polyacetaldehyde material, including a bolt body 1-1. The bolt body 1-1 is divided into an upper and lower parts. The lower part of the bolt body 1-1 is configured as an annular groove structure so that the lower part of the bolt body 1-1 forms a cylindrical connecting neck with end plates on both sides, which is used to connect the longitudinal connecting rods into a string and enable the longitudinal connecting rods to have the ability to rotate. The upper part is configured as a threaded rod-shaped part, which is an extension of the lower annular groove structure and is used to insert and fix the transverse positioning piece; the overall height of the positioning bolt is 11mm, the maximum diameter is 8mm, the inner diameter of the bolt body 1-1 is 3mm, and the threaded part is 6mm long. The annular groove structure is provided with two raised baffles 1-2, which are relatively small, 1.4mm long and 1.5mm wide, and are used to constrain the rotation range of the longitudinal connecting rod. Among the two raised baffles 1-2, one of the raised baffles 1-2 is a first raised baffle, the upper surface of which is directly connected to the upper groove wall of the annular groove structure as a whole, and there is an appropriate gap between the lower surface of the first raised baffle and the lower groove wall of the annular groove structure, while the other raised baffle 1-2 is a second raised baffle, the lower surface of which is directly connected to the lower groove wall of the annular groove structure as a whole, and there is an appropriate gap between the upper surface of the second raised baffle and the upper groove wall of the annular groove structure. It can be seen that the present invention arranges the first and second raised baffles in the annular groove structure so that the annular groove structure is in a horizontal position ( Figure 2 On both sides of the left and right directions, there are two limit installation grooves for embedding the left and right longitudinal connecting rods, and the two limit installation grooves correspond to the first and second limit installation grooves, which are staggered in height with each other.

[0055] like Figure 3 As shown, the longitudinal connecting rod 3 is a strip-shaped rod with clamping tube structures 3-1 at each end. The clamping tube structures 3-1 are staggered in height, with a center-to-center distance of 40 mm. The clamping tube structures 3-1 are designed to fit within the annular groove structure below the positioning bolt and engage the cylindrical connecting neck of the annular groove structure. The longitudinal connecting rod 3 is 44 mm long, 8 mm wide, and 5 mm thick. The clamping tube structures 3-1 correspond to first and second clamping tube structures. The height and shape of the first clamping tube structure match the first position-limiting mounting groove, while the height and shape of the second clamping tube structure match the second position-limiting mounting groove. During assembly, the first clamping tube structure fits within the first position-limiting mounting groove, and the second clamping tube structure fits within the second position-limiting mounting groove.

[0056] like Figure 4As shown, the transverse positioning piece 4 is a sheet-like rod with an overall thickness of 2 mm. It includes a U-shaped piece 4-2 positioned in the central region. Ring-shaped positioning structures 4-1 are positioned at both ends of the U-shaped piece 4-2. The ring-shaped positioning structures 4-1 have an outer diameter of 24 mm and an inner diameter of 18 mm. The inner diameter is the same as the diameter of the hole to be drilled and is used to mark the drilling location. A reserved hole 4-2 with a diameter of 6 mm is provided in the center of the U-shaped piece 4-2 for connecting the positioning bolt 1.

[0057] like Figure 5 As shown, the annular magnet 5 and the positioning bolt 1 are bonded together with strong glue, which is the first step. The second step is to connect the positioning bolt 1 and the longitudinal connecting rod 3 in sequence to form a chain-like structure, and then adsorb it to the surface of the steel box girder according to the crack. The third step is to install the transverse positioning piece 4 on the upper part of the positioning bolt 1, adjust the angle, and then secure it with the nut 2. The installation is completed.

[0058] The longitudinal connecting rod 3 is connected to the positioning bolt 1 through the clamping tube structure 3-1, which can realize the drilling positioning of cracks of any length. Figure 6 As shown; the longitudinal connecting rod 3 and the transverse positioning piece 4 are connected by a positioning bolt 1, which can achieve rotation within a certain range and can realize the drilling positioning of the arc-shaped crack. The structure is as shown Figure 7 shown.

[0059] like Figure 8 As shown: The installation steps of the above drilling positioning device are as follows:

[0060] Step A: Determine the crack length and prepare the required parts: Purchase the annular magnet 5 according to the designed size; Make steel molds for the remaining parts according to the designed size and shape, and use the plastic injection molding method to make them; Determine the number of parts required based on the crack length.

[0061] Step B, preliminary assembly: prepare the parts, stick the annular magnet 5 to the bottom of the positioning bolt 1, and connect the positioning bolt 1 and the longitudinal connecting rod 3 in sequence to form a chain-like structure.

[0062] Step C, linear positioning: According to the direction of the crack to be reinforced, adjust the linear shape of the chain structure to match the crack to complete the preliminary positioning; observe the relative position of the positioning bolt 1 and the crack through the cylindrical structure set on the positioning bolt 1, and continuously adjust it to make the positioning bolt 1 coincide with the crack.

[0063] Step D, installation of transverse positioning pieces: After the linear positioning is completed, install the transverse positioning pieces 4 and rotate them to adjust their relationship with the linear shape. The transverse positioning pieces 4 at the beginning and end are perpendicular to the linear shape, and the rest are kept near the angle bisector of the linear angle. After the position adjustment is completed, screw in the nut 2 to tighten it. The operation of each transverse positioning piece 4 is the same.

[0064] Step E, drilling positioning: Use a marker pen to mark the surface of the steel box girder through the transverse positioning piece 4 to complete the positioning.

[0065] Step F, device disassembly: Loosen nut 2 and remove the horizontal positioning piece; use a little force to remove the chain-like structure. The chain-like structure does not need to be removed and can be left for the next place to be reinforced. Continue to use after adjustment.

Claims

1. A positioning device for steel box girder array steel bar reinforcement, used for locating cracks on steel box girders, characterized in that: It includes a magnetic positioning connecting chain and a transverse positioning piece, wherein: The magnetic positioning connection chain is arranged along the direction of extension of the crack length and includes magnetic positioning bolts and longitudinal connecting rods; the number of magnetic positioning bolts is M, and the number of longitudinal connecting rods is M-1, where M ≥ 1; the number of magnetic positioning bolts and longitudinal connecting rods is matched according to the length of the crack, and two adjacent magnetic positioning bolts are connected by a longitudinal connecting rod, and the connection between the magnetic positioning bolts and the longitudinal connecting rod is an anchor connection; each magnetic positioning bolt is magnetically adsorbed and installed on the crack one by one at intervals; The described transverse positioning piece is provided with a transverse positioning piece relative to the position of each magnetic positioning bolt; each transverse positioning piece is arranged across the crack, and the middle part of the transverse positioning piece can be locked with the magnetic positioning bolt at the corresponding position through a nut, and at the same time, two annular positioning structures for locating the drilling position are symmetrically provided at both ends of the transverse positioning piece.

2. The positioning device for array steel bar reinforcement of steel box beams according to claim 1, characterized in that: The magnetic positioning bolt comprises a positioning bolt and an annular magnet installed at the bottom of the positioning bolt.

3. The positioning device for array steel bar reinforcement of steel box beams according to claim 2, characterized in that: The positioning bolt includes a bolt body; the bolt body is divided into an upper and lower part, and the lower part of the bolt body is provided with two staggered limiting mounting grooves, while the upper part of the bolt body is provided with a threaded rod-shaped portion that cooperates with the nut; the two limiting mounting grooves correspond to the first and second limiting mounting grooves; One end of the longitudinal connecting rod is provided with a first clamping tube structure that can be embedded in the first limiting installation groove, and the other end is provided with a second clamping tube structure that can be embedded in the second limiting installation groove; both the first and second clamping tube structures can rotate around the magnetic positioning bolt at the installation position.

4. The positioning device for array steel bar reinforcement of steel box beams according to claim 3, characterized in that: The transverse positioning piece includes a U-shaped piece; both side arms of the U-shaped piece extend outward to form connecting end ears to respectively connect with the two annular positioning structures, and the closed end of the U-shaped piece is provided with a reserved hole at the middle position; The reserved hole of the U-shaped piece is sleeved on the periphery of the threaded rod-shaped portion and is locked with a corresponding positioning bolt through a nut.

5. The positioning device for array steel bar reinforcement of steel box beams according to claim 3, characterized in that: The lower part of the bolt body is provided with an annular groove structure, and the annular groove structure has two raised baffles provided on both sides of the positioning bolt, and the two raised baffles are respectively referred to as the first and second raised baffles; Two position-limiting mounting grooves that are staggered in height are formed in the annular groove structure by the first and second raised baffles.

6. The positioning device for array steel bar reinforcement of steel box beams according to claim 5, characterized in that: The upper surface of the first raised baffle is directly connected to the upper groove wall of the annular groove structure as a whole, and there is a gap between the lower surface of the first raised baffle and the lower groove wall of the annular groove structure suitable for embedding the second clamping tube structure; The lower surface of the second raised baffle is directly connected to the lower groove wall of the annular groove structure as a whole, and there is a gap between the upper surface of the second raised baffle and the upper groove wall of the annular groove structure suitable for embedding the first clamping tube structure.

7. The positioning device for array steel bar reinforcement of steel box beams according to claim 1, characterized in that: The magnetic positioning bolt is provided with a central through hole along the axis.

8. The positioning device for array steel bar reinforcement of steel box beams according to claim 1, characterized in that: The diameter of the annular positioning structure is the same as the diameter of the drill hole to be positioned.

9. The positioning device for array steel bar reinforcement of steel box beams according to claim 1, characterized in that: The longitudinal connecting rod is made of plastic POM polyacetaldehyde material.

10. A positioning method for steel box girder array steel bar reinforcement, based on the positioning device for steel box girder array steel bar reinforcement according to claim 2, characterized in that: The steps include: Step A: Determine the crack length and prepare the required parts Determine the matching number of positioning bolts, annular magnets, longitudinal connecting rods, transverse positioning pieces, and nuts based on the length of the crack to be reinforced; Step B: Assemble the magnetic positioning connection chain First, the annular magnets are glued one by one to the bottom of the corresponding positioning bolts to form magnetic positioning bolts; then the magnetic positioning bolts are sequentially connected with the longitudinal connecting rods to form a chain-like structure to obtain a magnetic positioning connection chain; Step C: Linear positioning According to the direction of the crack to be reinforced, adjust the linear shape of the magnetic positioning connection chain to match the crack to be reinforced to complete the preliminary positioning; then observe the relative position of the magnetic positioning bolt and the crack to be reinforced through the central through-hole set on the magnetic positioning bolt, and continuously adjust it until the center of the magnetic positioning bolt can coincide with the crack to be reinforced; Step D: Install the lateral positioning piece After the linear positioning is completed, install the transverse positioning pieces and rotate them to adjust their relationship with the overall linear shape of the magnetic positioning connection chain. The transverse positioning pieces installed at the beginning and end of the magnetic positioning connection chain are perpendicular to the overall linear shape of the magnetic positioning connection chain, and the remaining transverse positioning pieces are kept near the angle bisector of the overall linear angle of the magnetic positioning connection chain. After the position adjustment is completed, screw in the nuts and tighten them. Step E: Drilling Positioning Use the transverse positioning piece to mark the surface of the steel box girder to complete the positioning; Step F: Device disassembly Loosen the nut, remove the lateral positioning piece, and finally remove the magnetic positioning connecting chain.

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