Thermal repair method for fatigue cracks of steel bridge diaphragm plate

Abstract

The invention relates to a thermal repair method for fatigue cracks of a steel bridge diaphragm plate. The method comprises the following steps: detecting a fatigue crack in the diaphragm plate of the steel bridge, and determining the extension trend of the fatigue crack; applying pretension to the two sides of the fatigue crack, wherein the pretension is used for enabling the opening gap of the fatigue crack to reach a preset size; grooves are formed in the metal, located on the two sides of the fatigue crack, in the steel bridge diaphragm plate in the extending direction of the fatigue crack; according to the steel strength grade and the quality grade of the steel bridge diaphragm plate, a corresponding welding material is obtained through matching; and carrying out thermal repair on the fatigue crack by adopting the welding material. By means of the method, the possibility that the steel bridge diaphragm plate is subjected to fatigue cracking again from the arc-shaped notch can be fundamentally eliminated, and the purpose of repairing fatigue cracks is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of steel bridge maintenance and reinforcement, and in particular to a method for thermally repairing fatigue cracks of a steel bridge diaphragm. Background Art

[0002] my country introduced steel bridge deck technology in the early 1970s, and began to build steel bridges with steel bridge decks on a large scale in the 1990s. So far, a large number of steel bridges with steel bridge decks have been built in China. However, due to the overall level of cognition and design of steel bridge decks at that time, some steel bridges developed a large number of fatigue cracks soon after they were put into use. Among them, the number of fatigue cracks generated at the arc-shaped notch of the diaphragm was relatively large, accounting for more than 30%, which directly affected the safety of bridge structures and driving safety.

[0003] At present, fatigue cracks at the arc-shaped notch of the diaphragm are generally repaired by welding, bolting steel plates or pasting carbon fiber composite materials. However, after the welding method is used for repair, fatigue cracks often reappear on or near the repaired weld; the bolting steel plate method has high requirements for the treatment of the bolted surface, and the construction site often cannot meet the treatment conditions, which affects the repair effect; pasting carbon fiber composite materials to repair fatigue cracks has high requirements for the performance of structural adhesives, and the pasting process is relatively harsh, which makes the construction difficult. Summary of the invention

[0004] Based on this, it is necessary to provide a thermal repair method for fatigue cracks in the cross diaphragm of a steel bridge, which is quick and convenient to construct and not prone to fatigue cracks occurring again, in order to address the above technical problems.

[0005] In a first aspect, the present application provides a method for thermally repairing fatigue cracks of a steel bridge diaphragm, comprising:

[0006] Detect fatigue cracks in steel bridge diaphragms and determine the propagation direction of the fatigue cracks;

[0007] Applying pre-tension on both sides of the fatigue crack, wherein the pre-tension is used to make the gap opened by the fatigue crack reach a preset size;

[0008] Beveling the metal on both sides of the fatigue crack in the steel bridge diaphragm along the extension direction of the fatigue crack;

[0009] According to the steel strength grade and quality grade of the steel bridge diaphragm, corresponding welding materials are matched;

[0010] The fatigue cracks are thermally repaired using the welding material.

[0011] In one of the embodiments, the pre-tension is used to make the gap opened at the heel of the fatigue crack larger than 2 mm, and the pre-tension does not exceed the metal yield strength of the steel bridge diaphragm.

[0012] In one embodiment, the thermal repair of the fatigue crack using the welding material includes:

[0013] The welding material is welded at the fatigue crack using a preset line energy.

[0014] In one embodiment, the energy threshold of the preset line energy does not exceed 15 kJ / cm.

[0015] In one embodiment, after the fatigue crack is thermally repaired by the welding material, the method further comprises:

[0016] The welds formed by heat repair in the steel bridge diaphragm are polished and smoothed.

[0017] In one embodiment, before the welding seam formed by thermal repair in the steel bridge diaphragm is polished and smoothed, the method further comprises:

[0018] Performing ultrasonic flaw detection on the weld to obtain defect detection results of the weld;

[0019] Determine that the defect detection result is no defect.

[0020] In one embodiment, after detecting fatigue cracks in the diaphragm of the steel bridge and determining the extension direction of the fatigue cracks, the method further includes:

[0021] A crack-stop hole is drilled at the tip position of the fatigue crack, and the crack-stop hole covers the tip position.

[0022] In one embodiment, the diameter of the crack-stop hole is 25 mm.

[0023] In one of the embodiments, the groove is a 40°-50° single-sided double-sided symmetrical groove, and the gap of the groove is 4-8 mm.

[0024] In one embodiment, after the fatigue crack is thermally repaired by the welding material, the method further comprises:

[0025] The pre-tensioning force is released.

[0026] The above-mentioned method for thermal repair of fatigue cracks in the steel bridge diaphragm determines the expansion direction of the fatigue cracks by detecting the fatigue cracks in the steel bridge diaphragm; applies pre-tension on both sides of the fatigue crack, and the pre-tension is used to make the gap of the fatigue crack reach a preset size; along the expansion direction of the fatigue crack, the metal on both sides of the fatigue crack in the steel bridge diaphragm is beveled; the corresponding welding material is matched according to the steel strength grade and quality grade of the steel bridge diaphragm; the fatigue cracks are thermally repaired with welding materials, which is not only quick and convenient in construction, but also greatly reduces the fatigue stress amplitude of the repaired steel bridge diaphragm at the arc-shaped notch in the service state, fundamentally eliminating the possibility of fatigue cracking of the steel bridge diaphragm from the arc-shaped notch again, thereby achieving the purpose of repairing fatigue cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] FIG1 is an application environment diagram of a method for thermally repairing fatigue cracks in a steel bridge diaphragm according to an embodiment;

[0029] Figure 2 A schematic flow chart of a method for thermally repairing fatigue cracks of a steel bridge diaphragm in one embodiment;

[0030] Figure 3 A schematic diagram of a step of drilling a crack-stop hole in an embodiment;

[0031] Figure 4 A schematic diagram of a pre-tensioning step in one embodiment;

[0032] Figure 5 A schematic diagram of a groove opening step in an embodiment;

[0033] Figure 6 A schematic flow chart of a method for thermally repairing fatigue cracks of a steel bridge diaphragm in another embodiment;

[0034] Figure 7 A schematic diagram of a steel bridge diaphragm after thermal repair in one embodiment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0037] It should be understood that spatial relationship terms such as "on both sides", "on both sides", "at the heel", "at the tip", "under", "below", "below", "below", "above", "above", etc., can be used here to describe the relationship between an element or feature shown in the figures and other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, the elements or features described as "below other elements" or "below" or "below" will be oriented as "above" other elements or features. Therefore, the exemplary terms "below" and "below" can include both upper and lower orientations. In addition, the device can also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0038] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, in this specification, the term "and / or" includes any and all combinations of the relevant listed items.

[0039] The thermal repair method for fatigue cracks of steel bridge diaphragms provided in the embodiment of the present application can be applied to the application environment shown in FIG1 , including: a bridge deck 102, a U-shaped rib 104, and a diaphragm 106. Among them, there is a crack 110 at the arc-shaped notch 100 at the intersection of the U-shaped rib 104 and the diaphragm 106.

[0040] The bridge deck 102 may be used to represent a load-bearing structure that directly bears vehicle wheel pressure and is usually made of reinforced concrete.

[0041] The U-rib 104 may be used to characterize a steel reinforcement skeleton used to strengthen the stability of a plate-beam structure in bridge construction. It is a component composed of steel bars and steel plates, usually in a "U" shaped cross section, hence the name "U-rib".

[0042] The diaphragm 106 may be used to represent a member disposed between beams to maintain a cross-sectional shape and enhance lateral stiffness.

[0043] In order to reduce welding stress, an arc-shaped notch 100 that does not need to be welded is usually provided between the U-shaped rib 104 and the diaphragm 106 .

[0044] There is usually an alternating effect of tension and compression cyclic stress at the arc notch 100, and the difference between the maximum positive stress and the minimum negative stress (positive stress and negative stress are determined according to the direction of the force, for example, when the tensile stress is positive stress, the compressive stress opposite to the tensile stress is negative stress, and vice versa) will constitute the fatigue stress amplitude at the arc notch 100. Fatigue stress amplitude is an important parameter in material fatigue analysis and can be used to evaluate the fatigue limit of materials or structures. In material fatigue life testing, fatigue stress amplitude can be used to evaluate the fatigue resistance of materials.

[0045] When the fatigue stress amplitude at the arc-shaped notch 100 exceeds the material fatigue strength of the diaphragm 106 , a crack 110 will appear. The crack 110 will gradually expand and become a fatigue crack on the surface of the diaphragm 106 .

[0046] In an exemplary embodiment, Figure 2 As shown, a method for thermally repairing fatigue cracks of a steel bridge diaphragm is provided, and the method is applied to the crack 110 in FIG. 1 as an example for explanation, including the following steps S202 to S210. Among them:

[0047] Step S202, detecting fatigue cracks in the diaphragm of the steel bridge and determining the propagation direction of the fatigue cracks.

[0048] Optionally, in some embodiments, image information of the steel bridge diaphragm may be collected and an image detection algorithm may be used to identify fatigue cracks in the steel bridge diaphragm and their propagation directions.

[0049] Alternatively, in some other embodiments, the penetrant can be applied or sprayed on the surface of the steel bridge diaphragm. The wetting ability and capillary phenomenon of the liquid are used to make the penetrant penetrate into the open defects on the surface of the steel bridge diaphragm. Then, the steel bridge diaphragm is applied with a developer, and an image of the steel bridge diaphragm after the developer is applied is collected. Image recognition processing is performed based on the collected image of the steel bridge diaphragm to determine the fatigue cracks in the steel bridge diaphragm and their extension direction. In this way, penetrant flaw detection for fatigue cracks is achieved.

[0050] Alternatively, in other embodiments, ultrasonic waves may be emitted to the steel bridge diaphragm, and the fatigue crack position and its propagation direction in the steel bridge diaphragm may be calculated based on the ultrasonic data received and returned from the steel bridge diaphragm.

[0051] Step S204: applying pre-tension on both sides of the fatigue crack, wherein the pre-tension is used to make the gap opened by the fatigue crack reach a preset size.

[0052] Among them, pre-tension can be used to characterize the external force applied to open the crack before crack repair.

[0053] For example, the working parameters of the special force-applying tool can be initialized and configured in advance according to the preset size required by the user. According to the location of the fatigue crack and its extension direction, the area on both sides of the fatigue crack that can be used to apply pre-tension is determined. The special force-applying tool after initialization is used to apply pre-tension on both sides of the fatigue crack so that the gap opened at the fatigue crack reaches a preset size. Since the pre-tension can change the stress state of the diaphragm structure of the steel bridge, the tensile stress amplitude at the fatigue crack can be reduced or even eliminated.

[0054] Step S206, along the extension direction of the fatigue crack, grooves are cut on the metal on both sides of the fatigue crack in the cross diaphragm of the steel bridge.

[0055] The groove can be used to refer to a groove of a certain geometric shape that is processed and assembled at the welded part (the metal part on both sides of the fatigue crack) in the cross diaphragm of a steel bridge. In the embodiment provided in the present application, the main purpose of opening the groove is to ensure the welding quality.

[0056] For example, mechanical cutting, flame cutting, cold stamping and other methods can be used to groove the metal on both sides of the fatigue crack in the cross diaphragm of the steel bridge along the extension direction of the fatigue crack, so as to increase the depth and width of the fatigue crack and facilitate the welding material to flow and fill the weld better in the subsequent welding process. At the same time, by groove the metal on both sides of the fatigue crack, the welding stress in the subsequent welding process can be reduced, and the risk of deformation and cracking in the welding process can be reduced.

[0057] Step S208, matching corresponding welding materials according to the steel strength grade and quality grade of the steel bridge diaphragm.

[0058] Among them, the steel strength grade can be used to reflect the tensile strength and bearing capacity of the steel bridge diaphragm.

[0059] The quality grade can be used to reflect the impact toughness and cold bending performance of steel bridge diaphragms at different temperatures, which is an important indicator to measure the performance of steel bridge diaphragms in harsh environments or stress conditions.

[0060] For example, the steel strength grade and quality grade of the steel bridge diaphragm and the metal material that can be used for welding can be queried from the material data stored in the local database or the Internet. When the steel strength grade and quality grade of the metal material and the steel strength grade and quality grade of the steel bridge diaphragm meet the following conditions: the steel strength grade and quality grade of the two are equal or the difference between the steel strength grade and quality grade of the two does not exceed a preset threshold, the currently compared metal material can be used as a welding material matching the steel bridge diaphragm.

[0061] Step S210: thermally repair fatigue cracks using welding materials.

[0062] Exemplarily, the thermal repair of the fatigue crack can be achieved by welding the welding material to the metal areas on both sides of the fatigue crack according to a thermal repair method such as a heating repair method, a stretching repair method, a repair agent repair method, and a welding repair method.

[0063] In the above-mentioned thermal repair method for fatigue cracks in the steel bridge diaphragm, the fatigue cracks in the steel bridge diaphragm are detected to determine the expansion direction of the fatigue cracks; pre-tension is applied on both sides of the fatigue crack, and the pre-tension is used to make the gap of the fatigue crack reach a preset size; along the expansion direction of the fatigue crack, the metal on both sides of the fatigue crack in the steel bridge diaphragm is beveled; the corresponding welding materials are matched according to the steel strength grade and quality grade of the steel bridge diaphragm; the fatigue cracks are thermally repaired with welding materials, which is not only quick and convenient in construction, but also greatly reduces the fatigue stress amplitude of the service state at the arc-shaped notch of the repaired steel bridge diaphragm, fundamentally eliminating the possibility of fatigue cracking of the steel bridge diaphragm from the arc-shaped notch again, thereby achieving the purpose of repairing fatigue cracks.

[0064] In an exemplary embodiment, the preset size may be 2 mm (millimeter).

[0065] Exemplarily, in this embodiment, pre-tension can be applied on both sides of the fatigue crack so that the gap at the heel of the fatigue crack is greater than 2 mm, and the pre-tension applied at this time needs to meet the condition of not exceeding the metal yield strength of the steel bridge diaphragm.

[0066] In this embodiment, by applying a pre-tension that does not exceed the metal yield strength of the steel bridge diaphragm, cracking or plastic deformation of the steel bridge diaphragm due to the application of pre-tension can be avoided. By applying pre-tension, the gap at the heel end of the fatigue crack is made larger than 2 mm, which is beneficial to improving the welding quality during the subsequent thermal repair of the fatigue crack.

[0067] In an exemplary embodiment, the above step S210 may also be implemented in the following manner:

[0068] The welding material is welded at the fatigue crack using a preset line energy.

[0069] Among them, line energy can refer to the energy input by the welding heat source to the weld per unit length during the welding process, usually in joules / cm (J / cm) or joules / millimeter (J / mm), also known as heat input. It is an important welding process parameter because it directly affects the quality and mechanical properties of the welded joint.

[0070] The calculation formula for line energy is: Q=IU / V, where Q represents line energy (kJ / cm), I is welding current (A), U is arc voltage (V), and V is welding speed (cm / min).

[0071] In this embodiment, by using a thermal repair method in which a preset line energy is used to weld the welding material at the fatigue crack, the advantage of the welding temperature and time that can be precisely controlled by the line energy can be utilized to improve the operational safety and welding quality of the thermal repair method.

[0072] In an exemplary embodiment, the energy threshold of the preset linear energy does not exceed 15 kJ / cm.

[0073] For example, in this embodiment, the welding material may be welded at the fatigue crack using a line energy with an energy threshold not exceeding 15 kJ / cm (kilojoules / cm).

[0074] In this embodiment, since the energy threshold of the preset energy does not exceed 15 kJ / cm, the effect of reducing the residual tensile stress generated by welding can be achieved.

[0075] In an exemplary embodiment, after executing step S210, the following steps may also be included:

[0076] Grinding smooth welds from heat repair in steel bridge diaphragms.

[0077] For example, when welding materials are welded at fatigue cracks, welds will be produced on the steel bridge diaphragm. After the fatigue crack thermal repair is completed, the welds formed by thermal repair in the steel bridge diaphragm can be polished to make the two ends of the welds smoothly transition and reduce stress concentration.

[0078] In this embodiment, by grinding the weld formed by thermal repair smoothly after the fatigue crack is repaired, the stress at the weld can be reduced and fatigue cracks can be prevented from occurring again in subsequent steel bridge diaphragms.

[0079] In an exemplary embodiment, before grinding the weld to be smooth, the following steps may also be included:

[0080] The weld is subjected to ultrasonic flaw detection to obtain the defect detection result of the weld; and the defect detection result is determined to be free of defects.

[0081] Among them, the defect detection results can be used to indicate whether there are cracks in the weld, whether there are areas where the welding material and the steel bridge diaphragm are not fused, whether there are slag inclusions and other defects.

[0082] For example, ultrasonic waves can be emitted to the weld obtained after the fatigue crack is thermally repaired, and ultrasonic echo data reflected from the weld can be received. The ultrasonic echo data can be processed using a preset defect detection algorithm to obtain a defect detection result of the weld. When it is determined that the defect detection result of the weld is defect-free, the weld can be polished and smoothed.

[0083] Optionally, in other embodiments, when the defect detection result of the weld shows that there are defects, such as cracks, lack of fusion or slag inclusions, the operation steps of thermally repairing the cracks with welding materials can be repeated.

[0084] In this embodiment, by performing ultrasonic flaw detection on the weld before grinding the weld, the welding quality of the thermal repair can be guaranteed, thereby avoiding the subsequent cracks in the steel bridge diaphragm.

[0085] In an exemplary embodiment, after the above step S202, the following may also be included:

[0086] A crack stop hole is drilled at the tip of the fatigue crack, and the crack stop hole covers the tip.

[0087] Among them, the crack stop hole can be used to characterize a hole drilled at its tip (that is, the end) to block the expansion of fatigue cracks. After subsequent repair, the hole is retained and not blocked.

[0088] For example, Figure 3 As shown, after determining the position of the fatigue crack 310 in the diaphragm 106 and its extension direction, the tip position of the end of the fatigue crack 310 can be located. A crack stop hole 320 can be drilled at the tip position of the fatigue crack 310. The crack stop hole 320 covers the tip position of the fatigue crack 310.

[0089] Alternatively, if Figure 4 As shown, after the crack-stop hole 320 is drilled, a pre-tension F may be applied on both sides of the fatigue crack 310 so that the gap opened by the fatigue crack 310 is greater than 2 mm.

[0090] In this embodiment, by drilling a crack-stop hole at the tip of the fatigue crack, the effect of blocking the expansion of the fatigue crack can be achieved.

[0091] In an exemplary embodiment, the diameter of the crack-stop hole may be 25 mm (millimeter).

[0092] In this embodiment, by using a crack stop hole with a hole diameter of 25 mm, the stress concentration at the crack tip can be eliminated, the stress level in the non-crack area of ​​the steel bridge diaphragm is increased, and the overall stress condition of the steel bridge diaphragm is improved.

[0093] In an exemplary embodiment, the groove is a 40°-50° single-sided double-sided symmetrical groove, and the gap of the groove is 4-8 mm.

[0094] For example, Figure 5 As shown, in the process of beveling the metal area on both sides of the fatigue crack in the steel bridge diaphragm 106, a single-sided and double-sided symmetrical bevel of 40°-50° (the angle between the two sides of the bevel) can be obtained, and the gap between the two sides of the bevel is 4-8mm. The planed groove 530 is connected to the crack stop hole 320. The stress on both sides of the planed groove 530 points to the direction of the crack stop hole 320.

[0095] In this embodiment, by adopting a groove opening method in which the groove is a 40°-50° single-sided double-sided symmetrical groove and the groove gap is 4-8 mm, it is helpful to eliminate the stress concentration at the fatigue crack.

[0096] In an exemplary embodiment, after step S210, the following operations may also be performed:

[0097] Release the pre-tension.

[0098] For example, after the fatigue crack is thermally repaired, the pre-tension applied on both sides of the fatigue crack may be released.

[0099] Optionally, in some embodiments, after the fatigue crack thermal repair is completed, ultrasonic testing can be performed on the weld produced by the fatigue crack thermal repair. When the defect detection result obtained by the ultrasonic testing is defect-free, the weld is polished to be smooth. After the weld is polished to be smooth, the pretension on both sides of the fatigue crack is released.

[0100] In this embodiment, by releasing the pre-tension on both sides of the fatigue crack after thermal repair, fatigue cracks can be avoided from occurring again in the subsequent steel bridge diaphragm.

[0101] In an exemplary embodiment, Figure 6 As shown, a method for thermally repairing fatigue cracks of a steel bridge diaphragm is also provided, comprising the following steps S602 to S616. Among them:

[0102] Step S602, detecting fatigue cracks in the diaphragm of the steel bridge and determining the propagation direction of the fatigue cracks.

[0103] For example, fatigue cracks in the diaphragm of a steel bridge and their propagation direction and the position of the propagation tip can be determined by directly capturing images of the diaphragm of the steel bridge, or by applying or spraying penetrant and developer on the diaphragm of the steel bridge and then capturing images, or by emitting ultrasonic waves to the steel bridge.

[0104] Step S604, drilling a crack-stopping hole at the tip position of the fatigue crack, wherein the crack-stopping hole covers the tip position.

[0105] For example, a crack-stop hole with a diameter of 25 mm may be drilled at the tip of the fatigue crack, and the crack-stop hole needs to completely cover the propagation tip of the fatigue crack.

[0106] Step S606: applying pre-tension on both sides of the fatigue crack, wherein the pre-tension is used to make the gap opened by the fatigue crack reach a preset size.

[0107] For example, pre-tension can be applied on both sides of the fatigue crack so that the gap between the heel and end of the fatigue crack is greater than 2 mm. The pre-tension does not exceed the metal yield strength of the steel bridge diaphragm to avoid plastic deformation of the steel bridge diaphragm.

[0108] Step S608, along the extension direction of the fatigue crack, grooves are cut on the metal on both sides of the fatigue crack in the cross diaphragm of the steel bridge.

[0109] For example, under the operating condition of maintaining the pre-tension applied in step S606, the metal on both sides of the fatigue crack in the cross diaphragm of the steel bridge can be grooved along the extension direction of the fatigue crack. The angle of the groove is 40°-50°, and it is a single-sided and double-sided symmetrical groove, and the gap on both sides of the groove is 4-8 mm.

[0110] Step S610, according to the steel strength grade and quality grade of the steel bridge diaphragm, the corresponding welding material is matched and the welding material is welded at the fatigue crack using a preset line energy.

[0111] Exemplarily, under the operating condition of maintaining the pre-tension applied in step S606, a preset line energy of no more than 15 kJ / cm can be used to weld welding materials that match the steel strength grade and quality grade of the steel bridge diaphragm at the fatigue crack to minimize the residual tensile stress generated by welding.

[0112] Step S612, performing ultrasonic flaw detection on the weld to obtain a defect detection result of the weld.

[0113] Exemplarily, under the operating condition of maintaining the pre-tension applied in step S606, ultrasonic waves can be emitted to the weld formed after fatigue crack thermal repair, and ultrasonic flaw detection can be performed on the weld based on the ultrasonic echo data returned from the weld to detect whether there are defects such as incomplete fusion, cracks or slag inclusions in the weld.

[0114] Step S614, when it is determined that the defect detection result is defect-free, the weld formed by thermal repair in the steel bridge diaphragm is polished to be smooth.

[0115] Exemplarily, under the operating condition of maintaining the pretension applied in step S606, when the defect detection result is determined to be defect-free, the welds formed by thermal repair in the cross diaphragm of the steel bridge can be polished smooth to achieve a smooth transition at both ends of the weld to reduce stress concentration.

[0116] Step S616, releasing the pre-tension.

[0117] Exemplarily, after the above steps S606 to S614 are executed, the pre-tension applied on both sides of the fatigue crack may be released.

[0118] like Figure 7 As shown, by adopting the thermal repair method provided in this embodiment, since the weld is polished smooth after repair, the structural stress concentration effect of the diaphragm 106 is equivalent to that before repair, so the fatigue strength of the diaphragm 106 at this time only depends on the strength grade and quality grade of the steel material, that is, only depends on the strength grade and quality grade of the steel material of the welding material. The strength grade and quality grade of the steel material of the welding material match the diaphragm 106. Therefore, it is possible to avoid the generation of fatigue cracks between the diaphragm 106 and the U-shaped rib 104 again.

[0119] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0120] Those skilled in the art will understand that the structures shown in the drawings of the present application are merely block diagrams of partial structures related to the scheme of the present application, and do not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device may include more or fewer components than those shown in the drawings, or combine certain components, or have a different arrangement of components.

[0121] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0122] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for thermally repairing fatigue cracks in a steel bridge diaphragm, characterized in that: The method comprises: Detect fatigue cracks in steel bridge diaphragms and determine the propagation direction of the fatigue cracks; Applying pre-tension on both sides of the fatigue crack, wherein the pre-tension is used to make the gap opened by the fatigue crack reach a preset size; Beveling the metal on both sides of the fatigue crack in the steel bridge diaphragm along the extension direction of the fatigue crack; According to the steel strength grade and quality grade of the steel bridge diaphragm, corresponding welding materials are matched; The fatigue cracks are thermally repaired using the welding material.

2. The method according to claim 1, characterized in that The pre-tensioning force is used to make the gap opened at the heel end of the fatigue crack larger than 2 mm, and the pre-tensioning force does not exceed the metal yield strength of the steel bridge diaphragm.

3. The method according to claim 1, characterized in that The method of using the welding material to thermally repair the fatigue crack comprises: The welding material is welded at the fatigue crack using a preset line energy.

4. The method according to claim 3, characterized in that: The energy threshold of the preset linear energy does not exceed 15 kJ / cm.

5. The method according to claim 1, characterized in that After the fatigue crack is thermally repaired by the welding material, the method further comprises: The welds formed by heat repair in the steel bridge diaphragm are polished and smoothed.

6. The method according to claim 5, characterized in that Before the weld seam formed by thermal repair in the steel bridge diaphragm is polished and smoothed, the method further comprises: Performing ultrasonic flaw detection on the weld to obtain defect detection results of the weld; Determine that the defect detection result is no defect.

7. The method according to claim 1, characterized in that After detecting the fatigue cracks in the diaphragm of the steel bridge and determining the extension direction of the fatigue cracks, the method further includes: A crack-stop hole is drilled at the tip position of the fatigue crack, and the crack-stop hole covers the tip position.

8. The method according to claim 7, characterized in that The aperture of the crack-stop hole is 25 mm.

9. The method according to claim 1, characterized in that: The groove is a 40°-50° single-sided double-sided symmetrical groove, and the gap of the groove is 4-8mm.

10. The method according to any one of claims 1 to 9, characterized in that After the fatigue crack is thermally repaired by the welding material, the method further comprises: The pre-tensioning force is released.

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