Method for calculating corrosion fatigue life of arch bridge suspender under axle coupling effect

Abstract

The invention relates to the technical field of arch bridge suspender fatigue life prediction, and belongs to an arch bridge suspender corrosion fatigue life calculation method under the axle coupling effect. Comprising the steps of establishing an arch bridge three-dimensional finite element model; calculating a train load; performing simulation analysis on the train passing through the arch bridge; after the train passes through the arch bridge, analyzing and outputting a stress time travel curve of the suspender when the single train passes through the arch bridge; converting the stress time history curve of the suspender when a single train passes through the arch bridge into a fatigue stress histogram to obtain the variable amplitude stress amplitude and the variable amplitude stress amplitude cycle index of the arch bridge suspender; calculating equivalent stress of the arch bridge suspender; measuring the initial corrosion pit size of the suspender, and calculating a suspender crack shape factor; calculating an initial crack size of the suspender, an adjacent crack size of the suspender and a suspender crack propagation corrosion acceleration factor; and establishing an arch bridge suspender corrosion fatigue life calculation formula under the axle coupling effect, and calculating the corrosion fatigue life of the arch bridge suspender. According to the method, the corrosion fatigue life of the arch bridge suspender can be accurately solved.

Description

Technical Field

[0001] The invention relates to the technical field of fatigue life prediction of arch bridge hangers, and in particular to a method for calculating the corrosion fatigue life of arch bridge hangers under vehicle-bridge coupling. Background Art

[0002] With the rapid development of high-speed railway construction in my country, long-span bridges have become the preferred option for overcoming terrain obstacles such as valleys, rivers, and oceans. In this context, arch bridges, due to their simple structure, clear load distribution, cost-effectiveness, aesthetic appeal, and reduced construction risks, have become a popular choice for long-span bridge design and construction. Furthermore, to embody the concept of sustainable development and the requirements of cost savings and environmental protection, more and more arch bridges are being used in our daily lives. During their operational life, the suspenders of arch bridges are subjected to tensile stresses and environmental corrosion from various cyclic loads. Suspenders are designed using high-strength steel wire with excellent fatigue performance and employ anti-corrosion measures such as galvanizing, heat shrink tubing, and cement slurry to prevent environmental corrosion. However, suspender damage includes heat shrink tubing failure, internal steel wire corrosion, and cracking. Long-term studies have shown that corrosion and fatigue are the main causes of suspender failure during their service life. Therefore, in addition to strengthening management measures such as design, construction, and maintenance, improving the service reliability of suspenders, conducting accurate safety risk analysis, and assessing the corrosion fatigue life of suspenders are essential considerations to ensure the safe operation of arch bridges.

[0003] Invention patent CN117610138A discloses a method for predicting the fatigue life of arch bridge hangers under the action of real-time traffic flow. Although a local standard fatigue model representing vehicles passing through the arch bridge and a bridge model of the hanger arch bridge are established, and the stress spectrum of each hanger of the arch bridge is obtained after loading the vehicle load, and the fatigue life of the hanger is calculated, the influence of corrosion factors on the hanger is not considered in the calculation of the hanger life. The high-strength steel wire used in the hanger of the arch bridge is a material that is very sensitive to corrosion. During the use of the hanger, long-term erosion by rain and humid air can easily cause corrosion damage to the hanger. Under normal traffic conditions, the hanger will produce a coupling effect of corrosion and fatigue, thereby accelerating the degradation of the hanger performance. The calculation method proposed in this invention patent does not consider the influence of corrosion factors on the hanger, which obviously has certain inaccuracies in the study of the hanger life.

[0004] Invention patent CN116562004A discloses a method for calculating the fatigue life of a suspender under a corrosion fatigue coupling state. The method takes into account the relationship between the fatigue load stress amplitude, the critical rust pit depth for the initiation of suspender cracks, the critical size of failure fracture, the environmental corrosion factors of chloride ion concentration, pH value, temperature, rust pit depth, and the critical size of failure fracture, and the number of fatigue cycles under the corrosion fatigue coupling state. The relationship is corrected through corrosion experiments, and the fatigue life of the suspender from pitting initiation to crack propagation is obtained. The life of the suspender from crack propagation to fracture is then obtained through the Paris law and the addition of corrosion influence. Although the calculation method takes into account the influence of corrosion factors on the suspender life, it does not take into account the actual operation of the arch bridge suspender, and does not reflect the stress amplitude of the suspender under the vehicle-bridge coupling. The calculation method proposed in this invention patent needs to be combined with the actual operation of the arch bridge to accurately calculate the life of the suspender. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for calculating the corrosion fatigue life of the suspenders of an arch bridge under the action of vehicle-bridge coupling, which accurately calculates according to the actual operating conditions of the arch bridge and solves the problem of calculation deviation of the corrosion fatigue life of the suspenders during the service of the arch bridge, so as to achieve more accurate safety risk analysis and evaluation of the corrosion fatigue life of the suspenders.

[0006] The present invention provides a method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling, comprising the following steps: Step 1: Establish a three-dimensional finite element model of the arch bridge based on the arch bridge structure information; Step 2: Determine the train speed and the parameters that affect the train load, calculate the train load, and form a train load spectrum; Step 3: Load the train load spectrum into the three-dimensional finite element model of the arch bridge and perform simulation analysis on the train passing through the arch bridge; Step 4: After the train passes the bridge, the stress time history curve of the suspender when a single train passes through the arch bridge is analyzed and output using general finite element software; Step 5: Convert the stress-time history curve of the suspender rod when a single train passes through the arch bridge into a fatigue stress histogram by using the rain flow counting method, and obtain the variable amplitude stress amplitude and the number of variable amplitude stress amplitude cycles of the suspender rod of the arch bridge; Step 6: Using the variable amplitude stress amplitude and the number of variable amplitude stress amplitude cycles of the arch bridge suspender through the equivalent stress calculation formula to obtain the equivalent stress of the arch bridge suspender; Step 7: Perform microscopic inspection on the boom, measure the initial pit size of the boom, and calculate the boom crack shape factor; Step 8, calculating the initial crack size of the suspender rod based on the material properties of the suspender rod; Step 9: Calculate the size of the adjacent cracks of the boom and the corrosion acceleration factor of the boom crack propagation based on the equivalent stress of the boom; Step 10: Based on the equivalent stress of the suspender, the initial pit size, the initial crack size, the adjacent crack size, and the crack propagation corrosion acceleration factor, a calculation formula for the corrosion fatigue life of the arch bridge suspender under vehicle-bridge coupling is established to calculate the corrosion fatigue life of the arch bridge suspender.

[0007] Furthermore, in step 1, a three-dimensional finite element model of the arch bridge is determined according to the structural dimension information of the arch bridge, and the grid size is divided according to the accuracy of the numerical calculation analysis results.

[0008] Furthermore, in step 2, the train load is calculated as follows:

[0009]

[0010]

[0011] In the formula is the train load, is the wheel static load, 、 is the vibration load under different conditions, is the unsprung mass of the train, For Yadaka, is the circular frequency, is the train speed, is the wavelength, T The time it takes for a train to cross the bridge.

[0012] Furthermore, in step 3, the train load is loaded into the three-dimensional finite element model of the arch bridge, the train load information is read in the order of time steps, and the train load moves on the arch bridge to simulate the train crossing the bridge.

[0013] Furthermore, in step 4, after the last carriage of the train goes down the bridge, the stress data of the suspenders in the arch bridge are analyzed by general finite element software, and the stress time history curve of the suspenders when a single train passes through the arch bridge is generated through time history post-processing.

[0014] Furthermore, in step 6, the calculation formula for the equivalent stress of the arch bridge suspender is:

[0015] Where, is the equivalent stress of the boom, is the variable amplitude stress amplitude, is the number of cycles of variable amplitude stress, is the material constant of the arch bridge hanger.

[0016] Furthermore, in step 7, the calculation formula of the hanger rod crack shape factor is:

[0017] In the formula is the shape factor of the hanger crack, is the diameter of the arch bridge hanger wire, is the initial pit size of the boom.

[0018] Furthermore, in step 8, the initial crack size of the hanger is calculated by the following formula:

[0019] Where: is the initial crack size of the suspender, is the fatigue crack growth threshold of the suspender rod, is the fatigue limit, is the shape factor of the hanger crack; Fatigue crack growth threshold of suspender rod and the yield strength of the suspender rod There is a corresponding relationship between the two:

[0020] In the formula is the boom fatigue crack growth threshold, is the yield strength of the suspender rod, It is the ratio of the maximum stress to the minimum stress in the stress-time curve of the hanger when a single train passes through the arch bridge.

[0021] Furthermore, in step 9, the size of the adjacent crack of the suspender rod is calculated by the following formula:

[0022] Where, is the size of the crack near the suspender, is the equivalent stress of the boom, Y is the shape factor of the hanger crack, is the average fracture toughness value of the suspender wire.

[0023] The corrosion acceleration factor of the boom crack growth is calculated by the following formula:

[0024]

[0025]

[0026]

[0027] In the formula is the crack growth corrosion acceleration factor, represents the pitting depth function, kThe depth of corrosion pits on the arch bridge suspenders after one year of service. The service life of the arch bridge suspenders. is the corrosion rate; 、 is the material constant of the arch bridge hanger, is the fatigue reduction factor, is the short crack fatigue index, is the short crack fatigue coefficient, is the equivalent stress of the boom, Y is the shape factor of the hanger crack, is the initial pit size of the boom, is the initial crack size of the suspender.

[0028] Furthermore, in step 10, the corrosion fatigue life calculation of the arch bridge hanger under vehicle-bridge coupling is divided into two stages. The first stage is the stage in which the initial corrosion pit of the hanger develops into the initial crack, and the second stage is the ductile-brittle expansion stage of the hanger crack. The calculation formulas are:

[0029]

[0030]

[0031] In the formula The life span of the boom from the initial corrosion pit to the initial crack stage, is the life of the ductile-brittle expansion stage of the suspender crack, is the corrosion fatigue life of the arch bridge hanger, is the initial pit size of the boom, is the initial crack size of the suspender, is the critical crack size of the suspender, 、 is the material constant of the arch bridge hanger, is the long crack fatigue coefficient, is the long crack fatigue index, is the equivalent stress of the boom, is the shape factor of the hanger crack.

[0032] The present invention provides a method for calculating the corrosion fatigue life of arch bridge hangers under vehicle-bridge coupling, which has the following technical effects: 1. The present invention can simulate the vehicle-bridge coupling effect of a bridge and more accurately calculate the equivalent stress of the arch bridge suspender under the vehicle-bridge coupling effect.

[0033] 2. The present invention can quickly and accurately calculate the corrosion fatigue life of arch bridge hangers under the coupling of vehicle and bridge, improve the service reliability of arch bridge hangers, accurately analyze safety risks, evaluate the corrosion fatigue life of hangers, and ensure the safety of arch bridge operation.

[0034] 3. The present invention uses general finite element software to perform vehicle-bridge coupling simulation analysis on arch bridges, which can reduce the high cost of on-site experiments while not affecting the normal traffic on the bridge, ensuring that railway operations are not disturbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the implementation principle of the present invention; Figure 2 A three-dimensional finite element model diagram of an arch bridge in an embodiment of the present invention; Figure 3 is an elevation view of an arch bridge according to an embodiment of the present invention; Figure 4 This is a diagram of a train load model in an embodiment of the present invention; Figure 5 The train load spectrum of a CRH3A train with a speed of 350 km / h in an embodiment of the present invention is shown in FIG. Figure 6 This is a fatigue stress histogram of the D1 and D18 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 7 This is a fatigue stress histogram of the D2 and D17 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 8 This is a fatigue stress histogram of the D3 and D16 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 9 This is a fatigue stress histogram of the D4 and D15 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 10 This is a fatigue stress histogram of the D5 and D14 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 11 This is a fatigue stress histogram of the D6 and D13 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 12 This is a fatigue stress histogram of the D7 and D12 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 13 This is a fatigue stress histogram of the D8 and D11 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 14 This is a fatigue stress histogram of the D9 and D10 suspenders when a single train passes through the bridge in an embodiment of the present invention; Figure 151 is the equivalent stress diagram of the arch bridge hanger in the embodiment of the present invention. DETAILED DESCRIPTION

[0036] like Figure 1 As shown, the present invention provides a method for calculating the corrosion fatigue life of arch bridge hangers under vehicle-bridge coupling, and the specific implementation process is as follows.

[0037] Step 1: Determine the three-dimensional finite element model of the arch bridge based on the structural size information of the arch bridge, and divide the grid size according to the accuracy of the numerical calculation analysis results.

[0038] Step 2: Determine the train speed and the parameters that affect the train load, and calculate the train load using the following formula: (1) (2) (3) In the formula is the train load, is the wheel static load, 、 is the vibration load under different conditions, is the unsprung mass of the train, For Yadaka, is the circular frequency, is the train speed, is the wavelength, T The time it takes for a train to cross the bridge.

[0039] Step 3: Load the train load into the three-dimensional finite element model of the arch bridge, read the train load information in the order of time steps, and move the train load on the arch bridge to simulate the train crossing the bridge, and perform simulation analysis on the train passing through the arch bridge.

[0040] Step 4: After the train passes the bridge, general finite element software is used to analyze and output the stress time history curve of the hanger when a single train passes through the arch bridge.

[0041] In this step, after the last carriage of the train goes down the bridge, the stress data of the arch bridge suspenders are analyzed using general finite element analysis software, and the stress time history curve of the suspenders when a single train passes through the arch bridge is generated through time history post-processing.

[0042] Step 5: The stress-time history curve of the suspender when a single train passes through the arch bridge is converted into a fatigue stress histogram by using the rain flow counting method to obtain the variable amplitude stress amplitude and the number of variable amplitude stress amplitude cycles of the arch bridge suspender.

[0043] Step 6: Using the variable amplitude stress amplitude and the number of variable amplitude stress amplitude cycles of the arch bridge hanger through the equivalent stress calculation formula to obtain the equivalent stress of the arch bridge hanger, wherein the equivalent stress calculation formula of the arch bridge hanger is: (4) Where, is the equivalent stress of the boom, is the variable amplitude stress amplitude, is the number of cycles of variable amplitude stress, is the material constant of the arch bridge hanger.

[0044] Step 7: Perform microscopic inspection on the boom, measure the initial pit size of the boom, and calculate the boom crack shape factor. The calculation formula of the boom crack shape factor is:

[0045] In the formula is the shape factor of the hanger crack, is the diameter of the arch bridge hanger wire, is the initial pit size of the boom.

[0046] Step 8: Calculate the initial crack size of the suspender rod according to the material properties of the suspender rod. The initial crack size of the suspender rod is calculated by the following formula: (6) Where: is the initial crack size of the suspender, is the boom fatigue crack growth threshold, is the fatigue limit, is the crack shape factor.

[0047] Fatigue crack growth threshold of suspender rod and the yield strength of the suspender rod There is a corresponding relationship between the two: (7) In the formula is the boom fatigue crack growth threshold, is the yield strength of the suspender rod, It is the ratio of the maximum stress to the minimum stress in the stress-time curve of the hanger when a single train passes through the arch bridge.

[0048] Step 9: Calculate the size of the adjacent crack of the suspender rod and the corrosion acceleration factor of the crack propagation of the suspender rod according to the equivalent stress of the suspender rod. The size of the adjacent crack of the suspender rod is calculated by the following formula: (8) Where, is the size of the crack near the suspender, is the equivalent stress of the boom,Y is the shape factor of the hanger crack, is the average fracture toughness value of the suspender wire.

[0049] The corrosion acceleration factor of the boom crack growth is calculated by the following formula: (9) (10) (11) (12) In the formula is the crack growth corrosion acceleration factor, represents the pitting depth function, k The depth of corrosion pits on the arch bridge suspenders after one year of service. The service life of the arch bridge suspenders. is the corrosion rate; 、 is the material constant of the arch bridge hanger; is the fatigue reduction factor, is the short crack fatigue index, is the short crack fatigue coefficient, is the equivalent stress of the boom, Y is the shape factor of the hanger crack, is the initial pit size of the boom, is the initial crack size of the suspender.

[0050] Step 10: Based on the equivalent stress of the suspender rod, the initial pit size, the initial crack size, the adjacent crack size, and the crack extension corrosion acceleration factor, a calculation formula for the corrosion fatigue life of the arch bridge suspender rod under vehicle-bridge coupling is established to calculate the corrosion fatigue life of the arch bridge suspender rod. The calculation of the corrosion fatigue life of the arch bridge suspender rod under vehicle-bridge coupling is divided into two stages: the first stage is the stage where the initial pit of the suspender rod develops into the initial crack, and the second stage is the ductile-brittle extension stage of the suspender rod crack. The calculation formulas are: (13) (14) (15) In the formula The life span of the boom from the initial corrosion pit to the initial crack stage, is the life of the ductile-brittle expansion stage of the suspender crack, is the corrosion fatigue life of the arch bridge hanger, is the initial pit size of the boom, is the initial crack size of the suspender, is the critical crack size of the suspender rod, 、 is the material constant of the arch bridge hanger, is the long crack fatigue coefficient, is the long crack fatigue index, is the equivalent stress of the boom, is the crack shape factor.

[0051] like Figure 2-Figure 15 As shown, the present invention is further illustrated below by describing the specific process of the embodiment of the present invention.

[0052] The arch bridge mentioned in this embodiment is a bottom-supported steel tube concrete arch bridge with a main span of 180m. The main beam adopts a single-box double-chamber, variable-height, straight-web box-section beam. The beam height at the center support of the main beam is 11m, and the lower edge of the beam bottom changes according to a quadratic parabola. For the arch ribs, the arch bridge adopts a vertical parallel steel tube concrete dumbbell arch structure, which starts from the bridge deck. The arch ribs adopt a quadratic parabola, with a center distance of 11.9m between the two arch ribs. The calculated span is 180m, and the rise-span ratio is 1:5. C55 self-compacting shrinkage-compensating concrete is poured into the arch rib steel tube and the abdominal cavity. Based on this, a three-dimensional finite element model of the arch bridge is established, as shown in the figure. Figure 2 shown.

[0053] The hangers are made of whole bundles of extruded steel strands with a tensile strength of no less than 1860MPa and a fatigue stress amplitude of 250MPa. Each hanger is composed of 12 steel wires with a diameter of 15.2mm. The hangers are evenly distributed along the longitudinal direction of the bridge. There are 36 sets of longitudinal double hangers in the whole bridge with a spacing of 9m. The hangers on both sides of the arch bridge are 13.5m away from the arch foot. The hangers are numbered D1-D18. Figure 3 shown.

[0054] In this embodiment, the train speed is 350 km / h and the train model is CRH3A. The train load is calculated by taking the wavelength and the rise as: ， The train load spectrum is generated according to formula (1), formula (2), and formula (3), as follows: Figure 5 shown.

[0055] The train load is loaded into the three-dimensional finite element model of the arch bridge, and the train passing through the arch bridge is simulated and analyzed; the eight-section high-speed train is simplified into thirty-two concentrated forces moving on the arch bridge to simulate the train crossing the bridge. The simplified train load model in this embodiment is as follows Figure 4 shown.

[0056] The stress time history curve of the suspender rod when a single train passes through the arch bridge in this embodiment is analyzed and output by general finite element software. The rain flow counting method program is written on the Matlab platform to convert the stress time history curve of the suspender rod when a single train passes through the arch bridge in this embodiment into a fatigue stress histogram, as shown in FIG. Figure 6-Figure 14 shown.

[0057] According to formula (4), the variable stress amplitude and the number of variable stress amplitude cycles of the arch bridge hanger in this embodiment are calculated to obtain the equivalent stress of the arch bridge hanger, as shown in the following example: Figure 15 shown.

[0058] According to formula (5), the shape factor of the hanger crack in this embodiment is calculated as , .

[0059] According to formula (6), the initial crack size of the hanger in this embodiment is calculated as follows: , .

[0060] According to formula (8), the adjacent crack size of the hanger in this embodiment is calculated as follows: The average fracture toughness of the suspension wire in this embodiment is , the value is 61.4 , the adjacent crack size of the suspender in this embodiment is As shown in Table 1: Table 1 Size of adjacent cracks in the suspender rod

[0061] According to formula (9)-formula (12), the crack propagation corrosion acceleration factor of the hanger in this embodiment is calculated as follows: , as shown in Table 2: Table 2 Cracking corrosion acceleration factor of boom

[0062] According to formula (13), the first stage corrosion fatigue life of the boom in this embodiment is calculated as In this embodiment, the initial pit size of the boom is , arch bridge hanger material constant , .

[0063] According to formula (14), the second stage corrosion fatigue life of the boom in this embodiment is calculated as , the long crack fatigue coefficient in this embodiment is , long crack fatigue index , the corrosion fatigue life of the arch bridge hanger is shown in Table 3: Table 3 Corrosion fatigue life of arch bridge hangers

[0064] As shown in Table 3, suspenders D1, D18, D5, and D14 exhibited long corrosion fatigue lives, while suspenders D2 and D17, located on either side of the arch bridge, exhibited the shortest corrosion fatigue lives and are the weakest parts of the arch bridge. Therefore, in actual operational management, suspenders D2 and D17 must be prioritized for monitoring and maintenance. Based on the actual needs of high-speed rail operations, scientific and reasonable maintenance plans and emergency response plans should be developed to ensure rapid response and proper handling in the event of emergencies. By implementing these measures, we can effectively reduce the risk level of the arch bridge structure and ensure the safe and smooth operation of the high-speed rail.

Claims

1. A method for calculating the corrosion fatigue life of arch bridge hangers under vehicle-bridge coupling, characterized in that: The following steps are included: Step 1: Establish a three-dimensional finite element model of the arch bridge based on the arch bridge structure information; Step 2: Determine the train speed and the parameters that affect the train load, calculate the train load, and form a train load spectrum; Step 3: Load the train load spectrum into the three-dimensional finite element model of the arch bridge and perform simulation analysis on the train passing through the arch bridge; Step 4: After the train passes the bridge, the stress time history curve of the suspender when a single train passes through the arch bridge is analyzed and output by general finite element software; Step 5: Convert the stress-time history curve of the suspender when a single train passes through the arch bridge into a fatigue stress histogram by using the rain flow counting method, and obtain the variable amplitude stress amplitude and the number of variable amplitude stress amplitude cycles of the arch bridge suspender; Step 6: Using the variable amplitude stress amplitude and the number of variable amplitude stress amplitude cycles of the arch bridge suspender through the equivalent stress calculation formula to obtain the equivalent stress of the arch bridge suspender; Step 7: Perform microscopic inspection on the boom, measure the initial pit size of the boom, and calculate the boom crack shape factor; Step 8, calculating the initial crack size of the suspender rod based on the material properties of the suspender rod; Step 9: Calculate the size of the adjacent cracks of the boom and the corrosion acceleration factor of the boom crack propagation based on the equivalent stress of the boom; Step 10: Based on the equivalent stress of the suspender, the initial pit size, the initial crack size, the adjacent crack size, and the crack propagation corrosion acceleration factor, a calculation formula for the corrosion fatigue life of the arch bridge suspender under vehicle-bridge coupling is established to calculate the corrosion fatigue life of the arch bridge suspender.

2. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 1, the three-dimensional finite element model of the arch bridge is determined according to the structural size information of the arch bridge, and the grid size is divided according to the accuracy of the numerical calculation analysis results.

3. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 2, the train load is calculated as follows: In the formula is the train load, is the wheel static load, 、 is the vibration load under different conditions, is the unsprung mass of the train, For Yadaka, is the circular frequency, is the train speed, is the wavelength, T The time it takes for a train to cross the bridge.

4. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 3, the train load is loaded into the three-dimensional finite element model of the arch bridge. The train load information is read in the order of time steps, and the train load moves on the arch bridge to simulate the train crossing the bridge.

5. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 4, after the last carriage of the train goes down the bridge, the stress data of the suspenders in the arch bridge are analyzed using general finite element software, and the stress time history curve of the suspenders when a single train passes through the arch bridge is generated through time history post-processing.

6. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 6, the calculation formula for the equivalent stress of the arch bridge hanger is: Where, is the equivalent stress of the boom, is the variable amplitude stress amplitude, is the number of cycles of variable amplitude stress, is the material constant of the arch bridge hanger.

7. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 7, the calculation formula for the hanger rod crack shape factor is: In the formula is the shape factor of the hanger crack, is the diameter of the arch bridge hanger wire, is the initial pit size of the boom.

8. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 8, the initial crack size of the hanger rod is calculated by the following formula: Where: is the initial crack size of the suspender, is the boom fatigue crack growth threshold, is the fatigue limit, is the shape factor of the hanger crack; Fatigue crack growth threshold of suspender rod and the yield strength of the suspender rod There is a corresponding relationship between the two: In the formula is the boom fatigue crack growth threshold, is the yield strength of the suspender rod, It is the ratio of the maximum stress to the minimum stress in the stress-time curve of the hanger when a single train passes through the arch bridge.

9. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 1 is further characterized by: In step 9, the size of the adjacent crack in the hanger is calculated using the following formula: Where, is the size of the crack near the suspender, is the equivalent stress of the boom, Y is the shape factor of the hanger crack, is the average fracture toughness value of the suspender wire; The corrosion acceleration factor of the boom crack growth is calculated by the following formula: In the formula is the crack growth corrosion acceleration factor, represents the pitting depth function, k The depth of corrosion pits on the arch bridge suspenders after one year of service. The service life of the arch bridge suspenders. is the corrosion rate, 、 is the material constant of the arch bridge hanger, is the fatigue reduction factor, is the short crack fatigue index, is the short crack fatigue coefficient, is the equivalent stress of the boom, Y is the shape factor of the hanger crack, is the initial pit size of the boom, is the initial crack size of the suspender.

10. The method for calculating the corrosion fatigue life of an arch bridge hanger under vehicle-bridge coupling according to claim 9, further characterized by: In step 10, the calculation of the corrosion fatigue life of the arch bridge hanger under the vehicle-bridge coupling is divided into two stages. The first stage is the stage when the initial corrosion pit of the hanger develops into the initial crack, and the second stage is the ductile-brittle expansion stage of the hanger crack. The calculation formulas are: In the formula The life span of the boom from the initial corrosion pit to the initial crack stage, is the life of the ductile-brittle expansion stage of the suspender crack, is the corrosion fatigue life of the arch bridge hanger, is the initial pit size of the boom, is the initial crack size of the suspender, is the critical crack size of the suspender, 、 is the material constant of the arch bridge hanger, is the long crack fatigue coefficient, is the long crack fatigue index, is the equivalent stress of the boom, is the shape factor of the hanger crack.

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