In-service steel bridge U rib and top plate crack double-face welding repairing method and application thereof

Abstract

The invention relates to the technical field of bridge engineering, in particular to an in-service steel bridge U rib and top plate crack double-face welding repairing method and application thereof. The method comprises the steps that the position of a crack is determined, a bridge deck pavement layer above the crack is removed, and the surface of a bridge deck slab in a crack area is cleaned; flattening the bridge deck slab on the two sides of the crack, and fixing the flattened bridge deck slab; u-rib internal welding construction process holes are formed; u rib inner welding reinforcing welding and weld leg increasing welding are carried out in an inner corner area where the U rib with the cracks is connected with the top plate; sealing and repairing the construction process hole; carrying out carbon arc air gouging on the crack above the bridge deck slab, and forming a gouging groove in the bridge deck slab; and polishing and multi-layer and multi-pass welding are carried out on the planed groove. The method is fused with an internal welding technology, is a comprehensive repair scheme with root treatment, double reinforcement, controllable deformation and reliable quality, thoroughly overcomes the technical defects of treatment of symptoms, no treatment of root causes, easy secondary damage, poor reliability and the like in the prior art, and remarkably prolongs the service life and the safety performance of the in-service steel bridge.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, and more specifically, to a method for repairing cracks in the U-ribs and top plate of in-service steel bridges by double-sided welding and its application. Background Technology

[0002] Orthotropic steel bridge decks are widely used in long-span bridge structures due to their advantages such as light weight and high load-bearing capacity. However, under long-term vehicle loads and environmental effects, fatigue cracks are prone to appear at the weld joints connecting the U-ribs and the top plate, seriously affecting the structural safety and durability. Currently, common repair methods for U-rib cracks mainly include external welding repair, welding to seal crack arresting holes, and bonding steel plate reinforcement, but these methods all have certain limitations.

[0003] Method 1 (External Welding of Top Plate Surface): This method involves air gouging out grooves at the corresponding crack locations on the outer side of the bridge deck top plate to expose the interior of the cracks, followed by multi-layer, multi-pass welding to fill the gouged grooves. Although this method is relatively straightforward, it has significant drawbacks: First, the repair is limited to the top plate surface, and residual defects often remain at the crack roots at the inner corners of the U-ribs, making complete elimination difficult; second, the heat-affected zone generated during welding may lead to new stress concentrations, easily causing secondary cracking; furthermore, the large-area welding heat input may also cause local deformation of the bridge deck, affecting the structural geometry and load-bearing performance.

[0004] Method 2 (Crack Arrest Hole + Sealing Weld): This method involves drilling a crack arrest hole at the tip of the crack to prevent further crack propagation, and then sealing the hole and the crack surface with welding. Its disadvantages are: the crack arrest hole can only temporarily delay crack propagation and cannot fundamentally eliminate internal defects; furthermore, this method is only suitable for non-penetrating cracks, and for penetrated cracks, it still needs to be combined with other repair methods, resulting in limited repair effectiveness and insufficient long-term reliability.

[0005] Method 3 (Reinforcement with bonded steel plates): This method involves bonding steel plates to the cracked areas of the roof slab, using structural adhesives and bolts for fixation to distribute the load. However, adhesives are prone to aging under long-term environmental conditions, leading to degradation of bonding performance and making long-term reliability difficult to guarantee. Furthermore, this method can only inhibit the propagation of surface cracks to a certain extent and cannot effectively repair internal cracks, thus only addressing the symptoms, not the root cause.

[0006] In summary, existing U-rib crack repair methods all have limitations in different aspects, such as being unable to completely eliminate internal defects, having the risk of secondary cracking, or lacking long-term reliability.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a method for repairing cracks in the U-ribs and top plate of in-service steel bridges by double-sided welding. This method addresses the root cause and has advantages such as dual strengthening, controllable deformation, and reliable quality.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: One aspect of the present invention relates to a method for repairing cracks in the U-rib and top plate of an in-service steel bridge by double-sided welding, comprising the following steps: (a) Determine the location of the crack, remove the bridge deck pavement layer above the crack, and clean the bridge deck surface in the crack area; (b) Level the bridge deck on both sides of the crack and fix the leveled bridge deck; open the U-rib internal welding construction process holes; (c) Perform U-rib internal welding reinforcement and weld leg addition in the inner corner area where the U-rib and the top plate connect to the crack; seal the construction process holes; (d) Above the bridge deck, carbon arc gouging is performed on the crack to form a groove on the bridge deck; the groove is then ground and welded to form a multi-layer, multi-pass weld.

[0010] The aforementioned double-sided welding repair method for cracks in the U-ribs and top plate of in-service steel bridges is a comprehensive repair solution that addresses the root cause, strengthens the structure, controls deformation, and ensures reliable quality. It completely overcomes the technical defects of existing technologies, such as treating the symptoms but not the root cause, being prone to secondary damage, and having poor reliability, and significantly extends the service life and safety performance of in-service steel bridges.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention uses U-rib internal welding reinforcement welding technology to directly fuse and repair the root of the crack from the inside of the structure, completely eliminating the initial defects that cause the crack to start, thereby fundamentally avoiding the re-starting and expansion of the crack in the original place, and the repair effect is long-lasting and reliable.

[0012] (2) This invention creatively integrates internal root cause repair with external structural repair. First, the crack source is eliminated from the inside and the weak connection fillet weld is strengthened. Then, the outside of the top plate is grooved and welded, ultimately forming a complete and high-strength new weld from the inside to the outside. This dual mechanism not only repairs the damage, but also significantly improves the overall structural strength and fatigue resistance of the repaired area.

[0013] (3) The present invention first flattens the bridge deck and fixes it with temporary positioning welding before internal welding reinforcement and external grooving, which effectively constrains the plate; at the same time, the first completed inner corner weld plays a strong internal support role, which greatly enhances the rigidity of the area in the subsequent external air gouging and welding process, thereby controlling the local deformation caused by hot working to a minimum, and effectively ensuring the straightness and flatness of the repaired bridge deck.

[0014] (4) The present invention defines a series of strict process parameters and control standards to ensure the quality of each step of the operation. This refined process control greatly improves the reliability and durability of the repair project. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram showing the bridge deck before and after leveling. Figure 2 A schematic diagram of the cross-section of the weld seam added to the weld leg; Figure 3 This is a schematic diagram showing the changes in cracks before and after polishing. The dimensions in the diagram are in mm. Figure 4 This is a schematic diagram showing the repaired crack. Figure 5 This is a schematic diagram showing the positional relationship between the internal weld and the crack. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0018] One aspect of the present invention relates to a method for repairing cracks in the U-rib and top plate of an in-service steel bridge by double-sided welding, comprising the following steps: (a) Determine the location of the crack, remove the bridge deck pavement layer above the crack, and clean the bridge deck surface in the crack area; (b) Level the bridge deck on both sides of the crack and fix the leveled bridge deck; open the U-rib internal welding construction process holes; (c) Perform U-rib internal welding reinforcement and weld leg addition in the inner corner area where the U-rib and the top plate connect to the crack; seal the construction process holes; (d) Above the bridge deck, carbon arc gouging is performed on the crack to form a groove on the bridge deck; the groove is then ground and welded to form a multi-layer, multi-pass weld.

[0019] The present invention provides a double-sided welding repair method for cracks in the U-ribs and top plate of in-service steel bridges, achieving fundamental repair at the source of the crack and effectively preventing secondary cracking. Existing technologies (such as welding and bonding steel plates to the top plate surface) can only treat surface cracks and cannot reach the origin of fatigue cracks at the inner corner of the U-rib. The present invention, through U-rib internal welding reinforcement technology, directly fuses and repairs the crack root from within the structure, completely eliminating the initial defects that cause crack initiation (such as incomplete penetration), thereby fundamentally preventing the re-initiation and propagation of cracks at the original location, and providing a long-lasting and reliable repair effect.

[0020] This invention is not a simple surface or internal repair, but rather a creative fusion of internal root cause repair and external structural repair. First, the crack source is eliminated from within, and the weak fillet welds are strengthened. Then, slotted welding is performed on the exterior of the top plate, ultimately forming a complete, high-strength new weld from the inside out. This dual mechanism not only repairs the damage but also significantly improves the overall structural strength and fatigue resistance of the repaired area.

[0021] Traditional direct external air gouging and welding releases structural stress and introduces a large amount of heat, which can easily cause local warping deformation of the bridge deck. This invention, by leveling the bridge deck and fixing it with temporary locating welds before internal welding reinforcement and external grooving, effectively constrains the plates. Simultaneously, the pre-completed inner fillet welds provide strong internal support, greatly enhancing the rigidity of this area during subsequent external air gouging and welding processes. This minimizes the local deformation caused by hot working (misalignment ≤ 0.5mm), effectively ensuring the straightness and flatness of the repaired bridge deck.

[0022] Further, in step (a), the area for removing the pavement layer is defined as follows: along the crack direction, the removal length extends no more than 300 mm beyond each end of the crack (for example, it can be, but is not limited to, a point value or a range between any two of 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm, or 700 mm). This setting ensures sufficient working space for subsequent leveling, welding, and non-destructive testing operations. Extending a sufficiently large area beyond both ends and sides of the crack fully exposes the potential bridge deck deformation area caused by the crack, ensuring thorough treatment while facilitating observation of the complete crack direction to avoid omissions.

[0023] Further, in step (a), the cleaning scope (complete cleaning of the ground portion) is as follows: along the crack direction, the cleaning length extends ≥150mm beyond both ends of the crack (for example, it can be, but is not limited to, any point value or a range between any two of 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, or 500mm); perpendicular to the crack direction, the cleaning width extends ≥30mm on each side of the crack (for example, it can be, but is not limited to, any point value or a range between any two of 30mm, 40mm, 50mm, 60mm, 80mm, 100mm, 120mm, or 150mm). This grinding and cleaning within this scope aims to thoroughly remove contaminants (such as oil, rust, and coatings) that affect welding quality. It provides a wide, clean metal surface for subsequent welding, ensuring weld fusion quality and preventing defects such as porosity and slag inclusions in the weld. Cleaning beyond a certain range of the crack ensures that the weld heat-affected zone is also in a clean environment.

[0024] Furthermore, the bridge deck panels on both sides of the crack are leveled until the misalignment is ≤0.5mm (for example, it can be a point value or a range between any two of 0.01mm, 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, or 0.5mm). Leveling to ultra-high precision can effectively eliminate local deformation caused by crack development and restore the flatness of the bridge deck. This is a key prerequisite for ensuring uniform stress on the repaired structure, which can greatly reduce secondary stress concentration caused by geometric abrupt changes in the repair area, thereby significantly improving fatigue resistance.

[0025] Furthermore, the leveling is performed using a leveling machine; the leveling machine includes, but is not limited to, at least one of: welding clips, jacks, or lead screws.

[0026] Furthermore, the leveled bridge deck is secured using mechanical fixing and / or temporary locating welds. The length of the temporary locating weld is ≥60mm (for example, it can be a point value or a range between any two of 60mm, 70mm, 80mm, 90mm, or 100mm). Using a sufficiently long temporary locating weld provides strong and stable temporary fixation for the leveled bridge deck, preventing springback or displacement during subsequent complex internal welding and external air gouging processes. This ensures that the entire repair process is performed under precise geometric alignment, guaranteeing the final repair quality.

[0027] Furthermore, before performing U-rib internal welding reinforcement, a working hole should be made in the U-rib. The length of the working hole should be 50mm longer than the robot length and the height should be 20mm higher than the robot height. The hole should be located at the patching section.

[0028] This repair method incorporates U-rib internal welding technology, employing a double-sided welding repair approach. First, a welding robot is used to perform weld leg reinforcement welding inside the U-rib. Further, the weld leg size after reinforcement welding is ≥8mm (for example, it can be, but is not limited to, any point value or a range between any two of 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm). Increasing the weld leg size at the inner corner of the U-rib to ≥8mm through reinforcement welding significantly increases the effective load-bearing area and section modulus of the weld in this critical weak area. This not only strengthens the connection but, more importantly, provides a solid "protective layer" for the inner corner weld below during subsequent carbon arc gouging of the top plate, effectively preventing the gouging from penetrating or damaging the main internal reinforcing weld.

[0029] Furthermore, the length of the weld seam in the U-rib internal welding reinforcement extends at least 300mm beyond both ends of the crack longitudinally, such as... Figure 5 As shown.

[0030] The length of the reinforcement weld is much longer than the visible crack, ensuring that the reinforcement effect covers the potential damaged area (plastic zone) beyond the crack tip, forming a sufficiently long reinforced section. This smoothly transfers stress, avoiding the formation of new stress peaks at both ends of the repaired section, and fundamentally preventing the crack from re-initiating and propagating at the ends of the repaired area.

[0031] Furthermore, after the welding of the welded legs is completed, the openings in the U-ribs must be sealed.

[0032] The purpose of adding weld legs is to increase the size of the weld legs inside the U-rib elevation angle, and to prevent the inner corner reinforcement weld from being gouged through when the crack is removed by air gouging.

[0033] Furthermore, carbon arc gouging is performed at the top plate along the direction of the crack.

[0034] Further, after step (c) is completed, a groove is cut from the road surface into the crack. The length of the groove extends no more than 50 mm beyond both ends of the crack (for example, it can be any point value or a range between 5 mm, 10 mm, 20 mm, 40 mm, or 50 mm, or any value between two of these), and the crack is located at the center of the groove. This ensures that the air gouging groove completely covers the entire crack (including its possible extended tips), ensuring that all crack material is completely removed, eliminating the possibility of any micro-crack residue, and preparing for subsequent high-quality, defect-free welding.

[0035] Furthermore, the depth of the carbon arc gouging (which needs to cover all cracks, with a depth not exceeding 3mm of the crack depth) must meet the following requirements: single gouging depth ≤ 3mm (for example, it can be, but is not limited to, any one of 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, or 3mm, or a range between any two), and total gouging depth ≤ 10mm (for example, it can be, but is not limited to, any one of 0.1mm, 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm, or a range between any two). The "shallow gouging, multi-pass" process control, with a single gouging depth ≤ 3mm, facilitates precise control of the gouging groove depth, avoiding over-gouging damage to the underlying base material or internal welds. The total depth ≤ 10mm limitation is a scientifically set setting based on the original bridge deck thickness and internal weld height, preventing excessive gouging from gouging through the deck or excessively weakening the cross-section, thus ensuring structural safety.

[0036] Furthermore, the upper opening width of the groove is 12-14 mm (for example, it can be any one of 12 mm, 12.5 mm, 13 mm, 13.5 mm, or 14 mm, or a range between any two). Controlling the upper opening width of the groove within this range provides a bevel with a suitable width for welding operations, facilitating welding torch movement and metal deposition. If the width is too small, operation becomes difficult, and incomplete fusion is likely to occur; if the width is too large, unnecessary welding material filling and heat input will be increased, increasing the risk of deformation.

[0037] Furthermore, the two ends of the groove are formed with a gentle slope of not less than 1:5. At the two ends of the groove (the beginning and end points), there cannot be a vertical "cliff-like" cutoff; instead, a gentle slope must be created. The steepness (gradient) of this slope cannot exceed 1:5. The gentle slope treatment at both ends of the groove (gradient not less than 1:5) effectively avoids the generation of new stress concentration points.

[0038] Furthermore, the cracks are removed by grinding. During grinding, air-gouging carbon deposits and surface oxide scale should be removed to expose the metal's natural color, preventing the inner corner weld from being ground through.

[0039] Furthermore, dye penetrant testing or magnetic particle testing is used to ensure that the cracks are completely removed.

[0040] Furthermore, the grinding process requires removing the covering material within a 30mm area on both sides of the planing groove until the metal surface of the substrate is exposed.

[0041] This invention does not impose specific limitations on the processes of U-rib internal welding reinforcement, weld leg addition welding, and carbon arc gouging, and can make adaptive adjustments according to different construction environments and conditions.

[0042] This invention does not specifically limit the process of multi-layer and multi-pass welding, and can be adapted to different construction environments and conditions.

[0043] Furthermore, the multi-layer, multi-pass welding process also includes: inspecting the repaired cracks, grinding the welds, applying a coating to the repaired welded area, and filling the paving layer.

[0044] Another aspect of the present invention relates to a bridge repair method, including the aforementioned double-sided welding repair method for cracks in the U-ribs and top plate of an in-service steel bridge.

[0045] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0046] Example 1 The method for repairing cracks in the U-ribs and top plate of in-service steel bridges using double-sided welding provided in this embodiment includes the following steps: 1. Determine the location of the crack: Based on the crack detection results and the damage to the bridge deck pavement, determine the location where the U-rib weld root penetrates the crack, and mark the corresponding U-rib and its longitudinal position. 2. Remove the pavement layer in the cracked area: Based on the location of the crack and the extent of damage to the pavement layer, remove the pavement layer in the cracked area and clean the surface of the bridge deck in the cracked area. The requirements for pavement layer removal and subsequent treatment are as follows: (1) The cracks and their direction can be observed; (2) The scope of the pavement layer to be removed is as follows: along the direction of the crack, the removal length extends 300mm beyond both ends of the crack; perpendicular to the direction of the crack, the removal width extends 300mm on both sides of the crack. (3) The cleaning scope is as follows: along the direction of the crack, the cleaning length extends 150 mm beyond both ends of the crack; perpendicular to the direction of the crack, the cleaning width is 30 mm on each side of the crack. 3. Leveling and securing the bridge deck panels on both sides of the crack: Use leveling equipment to level the collapsed bridge deck panels, such as... Figure 1 As shown, the misalignment after leveling is 0.5mm. After leveling, temporary locating welds are used for fixation, and the length of the temporary locating welds is 60mm. 4. U-rib inner corner overhead welding: A construction process hole for U-rib inner welding is opened; U-rib inner welding reinforcement and weld leg addition are performed in the inner corner area where the cracked U-rib connects to the top plate. The construction process hole is then sealed. After weld leg addition in the corresponding area of ​​the crack, the weld leg size is 8mm, and the length of the additional weld extends 300mm beyond the longitudinal beginning and end of the crack. See the schematic diagram of the additional weld cross-section. Figure 2 ; 5. Carbon Arc Gouging for Cracks: Above the bridge deck, carbon arc gouging is performed along the crack direction to create a groove in the bridge deck. Weld marks are removed using gouging, grinding, or other methods. Carbon arc gouging must not damage the bridge deck base material. Any missing material in the deck should be repaired by welding and then ground smooth, without any welding defects. Carbon arc gouging must meet the following conditions: 1) Carbon arc gouging direction and length: Perform carbon arc gouging along the direction of the crack, with the length extending 80mm beyond both ends of the crack. The crack should be located in the center of the gouging groove, and the gouging groove should be smooth. 2) Gouging depth: The depth of a single layer of gouging should not exceed 3mm, and the cumulative depth of multiple carbon arc gougings should not exceed 10mm. When gouging, pay attention to the vertical direction and depth of the crack to prevent excessive gouging from damaging the inner corner weld. 3) Groove width: The top width of the groove is 14mm; 4) Slope at both ends of the groove: The slope at both ends of the groove length shall not be less than 1:5; 6. Grooving and Crack Removal: Use an angle grinder to grind the grooves and crack roots to thoroughly remove the cracks. Use dye penetrant testing or magnetic particle testing to ensure the cracks are completely removed. Figure 3 During grinding, carbon deposits and surface oxide scale from the air gouging should be removed to expose the metal's natural color, and grinding should be done to prevent the inner corner welds from being worn through. Oil stains within 30mm on both sides of the gouging groove should be removed to expose the metal's natural color. 7. Welding Repair: Multiple layers and passes of welding are used to fill the groove, forming a repair weld. See the image below after repair. Figure 4 As shown.

[0047] Example 2 The method for repairing cracks in the U-ribs and top plate of in-service steel bridges using double-sided welding provided in this embodiment includes the following steps: 1. Same as Example 1; 2. Remove the pavement layer in the cracked area: Based on the location of the crack and the extent of damage to the pavement layer, remove the pavement layer in the cracked area and clean the surface of the bridge deck in the cracked area. The requirements for pavement layer removal and subsequent treatment are as follows: (1) The cracks and their direction can be observed; (2) The scope of the pavement layer to be removed is as follows: along the direction of the crack, the removal length extends 350 mm beyond both ends of the crack; perpendicular to the direction of the crack, the removal width extends 350 mm on both sides of the crack. (3) The scope of cleaning is as follows: along the direction of the crack, the length of cleaning extends ≥200mm beyond both ends of the crack; perpendicular to the direction of the crack, the width of cleaning is 50mm on each side of the crack. 3. Leveling and fixing the bridge deck on both sides of the crack: Use a leveling machine to level the collapsed bridge deck. After leveling, the misalignment is 0.2mm. After leveling, fix it with temporary positioning welds. The length of the temporary positioning welds is 70mm. 4. U-rib inner corner overhead welding: Open construction process holes for U-rib inner welding; perform U-rib inner welding reinforcement welding and weld leg addition welding in the inner corner area where the U-rib and the top plate are connected and cracked; seal the construction process holes; after the weld leg addition welding in the area corresponding to the crack, the weld leg size is 10mm, and the length of the additional weld exceeds the longitudinal start and end of the crack by 320mm respectively. 5. Carbon Arc Gouging for Cracks: Above the bridge deck, carbon arc gouging is performed along the crack direction to create a groove in the bridge deck. Weld marks are removed using gouging, grinding, or other methods. Carbon arc gouging must not damage the bridge deck base material. Any missing material in the deck should be repaired by welding and then ground smooth, without any welding defects. Carbon arc gouging must meet the following conditions: 1) Carbon arc gouging direction and length: Perform carbon arc gouging along the direction of the crack, with the length extending 100mm beyond both ends of the crack. The crack should be located in the center of the gouging groove, and the gouging groove should be smooth. 2) Gouging depth: The depth of a single layer of gouging should not exceed 2mm, and the cumulative depth of multiple carbon arc gougings should not exceed 9mm. When gouging, pay attention to the vertical direction and depth of the crack to prevent excessive gouging from damaging the inner corner weld. 3) Groove width: The top width of the groove is 12mm; 4) Slope at both ends of the groove: The slope at both ends of the groove length shall not be less than 1:5; 6. Same as Example 1; 7. Same as Example 1.

[0048] Example 3 The method for repairing cracks in the U-ribs and top plate of in-service steel bridges using double-sided welding provided in this embodiment includes the following steps: 1. Same as Example 1; 2. Remove the pavement layer in the cracked area: Based on the location of the crack and the extent of damage to the pavement layer, remove the pavement layer in the cracked area and clean the surface of the bridge deck in the cracked area. The requirements for pavement layer removal and subsequent treatment are as follows: (1) The cracks and their direction can be observed; (2) The scope of the pavement layer to be removed is as follows: along the direction of the crack, the removal length extends 400mm beyond both ends of the crack; perpendicular to the direction of the crack, the removal width extends 400mm on both sides of the crack. (3) The cleaning scope is as follows: along the direction of the crack, the length of the cleaning extends ≥250mm beyond both ends of the crack; perpendicular to the direction of the crack, the width of the cleaning is 80mm on each side of the crack. 3. Leveling and fixing the bridge deck on both sides of the crack: Use a leveling machine to level the collapsed bridge deck. After leveling, the misalignment is 0.1mm. After leveling, fix it with temporary positioning welds. The length of the temporary positioning welds is ≥80mm. 4. U-rib inner corner overhead welding: Open construction process holes for U-rib inner welding; perform U-rib inner welding reinforcement welding and weld leg addition welding in the inner corner area where the U-rib and the top plate are connected and cracked; seal the construction process holes; after the weld leg addition welding in the area corresponding to the crack, the weld leg size is 15mm, and the length of the additional weld exceeds the longitudinal start and end of the crack by 350mm respectively. 5. Carbon Arc Gouging for Cracks: Above the bridge deck, carbon arc gouging is performed along the crack direction to create a groove in the bridge deck. Weld marks are removed using gouging, grinding, or other methods. Carbon arc gouging must not damage the bridge deck base material. Any missing material in the deck should be repaired by welding and then ground smooth, without any welding defects. Carbon arc gouging must meet the following conditions: 1) Carbon arc gouging direction and length: Perform carbon arc gouging along the crack direction, with the length extending 120mm beyond both ends of the crack. The crack is located in the center of the gouging groove, and the gouging groove is smooth. 2) Gouging depth: The depth of a single layer of gouging should not exceed 1.5mm, and the cumulative depth of multiple carbon arc gougings should not exceed 8mm. When gouging, pay attention to the vertical direction and depth of the crack to prevent excessive gouging from damaging the inner corner weld. 3) Groove width: The top width of the groove is 13mm; 4) Slope at both ends of the groove: The slope at both ends of the groove length shall not be less than 1:5; 6. Same as Example 1; 7. Same as Example 1.

[0049] Comparative Example 1 The only difference between this comparative example and Example 1 is in step (4), after the weld foot in the area corresponding to the crack is welded, the weld foot size is 6mm.

[0050] Comparative Example 2 The only difference between this comparative example and Example 1 is in step (4), where the length of the additional weld extends 280mm beyond the longitudinal beginning and end of the crack.

[0051] Comparative Example 3 The only difference between this comparative example and Example 1 is step (5), in which the groove length extends 70 mm beyond both ends of the crack.

[0052] Experimental Example The secondary cracking rate and local deformation were statistically analyzed for each embodiment and comparative example. The test method was laser ranging, and the test results are shown in Table 1.

[0053] Table 1

[0054] As shown in Table 1, the repair method provided by this invention has a low secondary cracking rate and a low local deformation rate.

[0055] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for repairing cracks between the U-rib and the top plate of an in-service steel bridge using double-sided welding, characterized in that... Includes the following steps: (a) Determine the location of the crack, remove the bridge deck pavement layer above the crack, and clean the bridge deck surface in the crack area; (b) Level the bridge deck on both sides of the crack and fix the leveled bridge deck; open the U-rib internal welding construction process holes; (c) Perform U-rib internal welding reinforcement and weld leg addition in the inner corner area where the U-rib and the top plate connect to the crack; seal the construction process holes; (d) Above the bridge deck, the crack is carbon arc gouged to form a groove on the bridge deck; The grooves are ground and welded to form a multi-pass weld.

2. The method for repairing cracks in the U-rib and top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, The bridge decks on both sides of the crack are straightened until the misalignment is ≤0.5mm.

3. The method for repairing cracks between the U-rib and the top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, After leveling, mechanical fixing and / or temporary locating welding are used for fixation.

4. The method for repairing cracks between the U-rib and the top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, Before performing U-rib internal welding reinforcement, a working hole is made in the U-rib, and it is sealed after welding is completed. The working hole is located in the patching section.

5. The method for repairing cracks between the U-rib and the top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, The weld leg size after the additional welding is ≥8mm.

6. The method for repairing cracks between the U-rib and the top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, The length of the weld seam for U-rib internal reinforcement should extend at least 300 mm beyond the beginning and end of the crack in the longitudinal direction.

7. The method for repairing cracks between the U-rib and the top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, After step (c) is completed, grooves are excavated from the road surface to the crack. The length of the grooves extends no more than 50 mm beyond both ends of the crack. The width of the top of the grooves is 12-14 mm. The two ends of the grooves form a gentle slope with a gradient of not less than 1:

5.

8. The method for repairing cracks between the U-rib and the top plate of an in-service steel bridge by double-sided welding according to claim 1, characterized in that, The single-pass air gouging depth of the carbon arc air gouging is ≤3mm.

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