A method for detecting and evaluating the operating state of a concrete support

Abstract

This invention discloses a method for detecting and evaluating the operational status of concrete supports, relating to the field of overhead contact line facility inspection technology. It solves the technical problem that existing technologies, relying on visual inspection, cannot accurately assess changes in the internal reinforced concrete and the overall load-bearing capacity of supports. The invention includes: S1: dividing the support into sections, rating the status of each section, and taking the section with the lowest rating as the overall visual damage evaluation level and obtaining the damage coefficient; S2: selecting multiple rebound test areas in each section to determine the concrete strength; S3: establishing a finite element model of the support, applying a preset load, and determining the location of the most unfavorable section; S4: fitting the prestress loss value of the prestressed tendons using an exponential decay function; S5: calculating the bending moment of the most unfavorable section based on the damage coefficient, ultimate strength, and prestress loss value, and calculating the support capacity margin based on the calculated bending moment and the design value, and determining maintenance recommendations based on the capacity margin. This invention has the advantages of accurately assessing the support status.

Description

Technical Field

[0001] This invention belongs to the field of overhead contact line facility testing technology, specifically relating to a method for testing and evaluating the operational status of concrete supports. Background Technology

[0002] As the load-bearing structure of the overhead contact network, the horizontal web support bears constant loads such as gravity, zigzag force and working tension of the conductor transmitted by the contact network, while also being subject to variable loads from random factors such as wind load, ice load and wire breakage. The prefabrication process of the horizontal web support has undergone strict process management, appearance inspection and quality inspection sampling. However, due to its long-term operation in the open environment, the overall structural strength of the support has been reduced.

[0003] Currently, research on railway cross-web support structures mainly focuses on the inspection of appearance, concrete strength, spatial location of reinforcing bars, and corrosion. Visual inspection primarily relies on foot patrols, vehicle patrols, or focused inspections under harsh weather conditions, using methods such as visual inspection, touch, and hammering to check for cracks, dents, and exposed reinforcing bars. In other words, current assessments of the operational status of cross-web support structures are limited to visual inspection, lacking an evaluation of internal changes in the reinforced concrete and the overall load-bearing capacity, making it difficult to effectively evaluate the support's operational status. Furthermore, while core drilling is used for concrete strength testing, it can cause structural damage. Non-destructive testing methods such as the rebound method do not consider prestress loss, and the half-cell potential method for reinforcing bar corrosion detection does not account for prestress decay over time. Therefore, a method that can comprehensively assess the operational status of support structures and provide maintenance recommendations is urgently needed. Summary of the Invention

[0004] In view of this, the present invention discloses a method for detecting and evaluating the operational status of concrete pillars, which aims to solve the technical problem that existing technologies rely on visual inspection and cannot accurately assess the changes in the internal reinforced concrete and the overall load-bearing capacity of the pillars.

[0005] To solve the aforementioned technical problems, the present invention adopts the following technical solution:

[0006] A method for detecting and evaluating the operational status of concrete pillars includes the following steps:

[0007] S1: Divide the support into sections, rate the condition of each section, take the section with the lowest rating as the overall appearance damage evaluation level and obtain the damage coefficient.

[0008] S2: Select multiple rebound test areas in each section to determine the concrete strength;

[0009] S3: Establish the finite element model of the support column, apply the preset load, and determine the location of the most unfavorable section.

[0010] S4: Fit the prestress loss value of the prestressed tendon using an exponential decay function;

[0011] S5: Calculate the bending moment of the most unfavorable section based on the damage coefficient, ultimate strength and prestress loss value, and calculate the support capacity margin based on the calculated bending moment and the design value, and determine the maintenance recommendation based on the capacity margin.

[0012] In this invention, by introducing an appearance-based rating method, the support column is divided into multiple sections for separate scoring, thereby more accurately determining the specific damage location and obtaining a more accurate damage coefficient. In S2, the concrete strength is determined by the rebound method. The rebound method is a method that uses a rebound hammer to impact the concrete surface and estimates the compressive strength of the concrete based on the rebound value. This is an existing technology. In this invention, by arranging multiple rebound test areas in each section, the weaker parts can be captured more accurately. In S3, a concrete and prestressed tendon model is established according to the actual size of the support column. By applying a predetermined load and performing finite element calculations, the weak points of the support column section stress can be accurately found. In S4, the prestressed tendons will experience stress loss due to factors such as steel relaxation and concrete shrinkage and creep during long-term use. The rate of stress loss follows a pattern of rapid initial loss followed by gradual loss over time. The exponential decay function can precisely describe this trend, thus providing accurate prestress parameters for subsequent calculations. Therefore, through the above S1-S5, this invention forms a complete evaluation system including appearance inspection, concrete strength determination, finite element analysis, prestress fitting, bending moment calculation, and evaluation decision-making, thereby achieving an accurate assessment of the support column condition.

[0013] Preferably, in S1, the support is divided into three sections: section I, section II, and section III. Section II is the ventral opening section, and section II is further divided into multiple units, each unit including a ventral opening.

[0014] After sampling this technical solution, it should be noted that the support structure is divided into three sections. Section I is located from the upper end of the perforation area to the top of the support, mainly bearing the load transmitted from above. Section II is located in the perforation area, which is a high-risk area for stress concentration and cracking due to the presence of several perforations. Section III is located from the lower end of the perforation area to the bottom of the support, bearing greater pressure and bending moment. The perforation area is further subdivided into units because damage between adjacent perforations may occur independently. Refining to the unit level allows for precise location of which specific perforation has cracked or exposed reinforcement, thus forming a refined evaluation with progressively focused attention.

[0015] Preferably, the rating of each segment in S1 includes:

[0016] Each unit is rated based on the presence of cracks and exposed reinforcement.

[0017] Each segment rating is obtained based on the rating results of each unit.

[0018] Preferably, the unit rating includes:

[0019] Grade A: The cross web and flanges of the column are free of cracks and exposed rebar;

[0020] Grade B: Cracks exist in the transverse web, but no cracks exist in the flanges, and the length of the transverse crack is less than or equal to the width of the support column. Or the length of the vertical crack is less than or equal to the width of the support column. The crack width is ≤0.3mm, or the transverse web is damaged or the exposed steel bars are ≤2, and the exposed length is ≤400mm, and there are no exposed steel bars on the flange;

[0021] Grade C: Cracks exist in the transverse web, but no cracks are found in the flanges, and the length of the transverse crack is greater than the width of the support column. Or the length of the vertical crack is greater than the width of the support column. And the crack width is ≤0.3mm, or the transverse web is damaged or there are more than 2 but less than or equal to 4 exposed steel bars, and the exposed length is ≤400mm, and there are no exposed steel bars or damage on the flange;

[0022] Grade d: The width of the crack in the transverse web is greater than 0.3 mm or there is a crack in the flange, or the transverse web is damaged or there are more than 4 exposed steel bars with a length greater than 400 mm.

[0023] After adopting this technical solution, it should be noted that crack length, width, and the number and length of exposed reinforcement are the most direct and quantifiable indicators for measuring the degree of appearance damage, and are easy to measure on site. Cracks are divided into transverse cracks and vertical cracks. Transverse cracks mainly affect the bending load-bearing capacity, while vertical cracks affect the shear resistance. The dimensions can be determined by on-site personnel using measuring tools.

[0024] Preferably, the segment rating includes:

[0025] Grade A: No Grade C units are rated, and the number of Grade B units is ≤20%;

[0026] Grade B: No Grade C in the unit rating, and the number of Grade Bs > 20%; or there are Grade Cs in the unit rating, and the number of Grade Cs ≤ 20%.

[0027] Grade C: There are Grade C units in the unit rating, and the number of Grade C units is greater than 20%;

[0028] Grade D: Unit rating includes a grade D;

[0029] The injury coefficient for Grade A is 1, for Grade B it is 0.9, and for Grade C it is 0.83.

[0030] After adopting this technical solution, it should be noted that the value of the appearance damage coefficient is determined by the section evaluation level, and suggestions are provided as follows:

[0031] The evaluation level is A, and the damage coefficient is... =1, which has virtually no impact on strength, and normal maintenance and inspection recommendations are given;

[0032] The evaluation level is B, and the damage coefficient is [missing information]. =0.9, which has little impact on strength; timely repair and enhanced inspection are recommended.

[0033] The evaluation level is C, and the damage coefficient is [missing information]. =0.83, the impact on strength is that the deterioration continues, and it is recommended to strengthen the inspection and take reinforcement measures when necessary;

[0034] A rating of D indicates that the product is at risk of being used, and a recommendation to discontinue its use is given.

[0035] Preferably, in S2, two rebound test areas are selected on the flange of section I, four rebound test areas are selected on the flange of section II, and two rebound test areas are selected on the flange of section III, and 16 test points are arranged in each rebound test area.

[0036] After adopting this technical solution, it should be noted that the number and location of the rebound test areas are based on the stress conditions and damage probability of different parts of the support. In section II, due to the presence of the ventral hole, pressure concentration is likely to occur. Therefore, four test areas are set up to conduct tests in a more dense area. In contrast, the stress conditions in sections I and II are relatively simple, so two test areas are arranged in each section.

[0037] Preferably, determining the concrete strength includes: obtaining the rebound values ​​of 16 measuring points in each rebound test area using the rebound method, removing the three maximum and minimum values ​​respectively, taking the average of the remaining 10 rebound values ​​as the representative rebound value of the rebound test area, and taking the minimum value of the 8 rebound test areas as the ultimate strength of the support column.

[0038] After adopting this technical solution, it should be noted that removing the three maximum and three minimum values ​​is a commonly used method for handling outliers. The average of the remaining 10 values ​​can represent the average intensity level of the survey area.

[0039] Preferably, S3 includes:

[0040] S3.1: Establish concrete and prestressed steel reinforcement models, set concrete plastic damage parameters, apply initial prestress to the prestressed tendons, and apply column base constraints.

[0041] S3.2: The location of the most unfavorable section is determined by the point where the stress changes abruptly in the cross section through finite element calculation.

[0042] After adopting this technical solution, it should be noted that the concrete uses a C3D8R grid, and the reinforcement uses linear subdivision. Before setting the concrete plastic damage parameters, the concrete elastic modulus E is first set, with E = 34500 MPa and a corresponding Poisson's ratio of 0.2. The concrete plastic damage parameters include an expansion angle of 40° and an eccentricity of 0.1. =1.16, k=0.6667, viscosity parameter is 0.002.

[0043] Preferably, the calculation of the bending moment at the most unfavorable section includes the calculation of the bending moment in the direction perpendicular to the track and in the direction along the track.

[0044] Preferably, the step of determining maintenance recommendations based on the capacity margin δ includes:

[0045] If δ > 3, the recommended usage is normal, and the maintenance cycle is 3 years.

[0046] 2.5<δ≤3, the recommended use is to increase inspections, and the maintenance cycle is 1 year;

[0047] If 2 < δ ≤ 2.5, the recommended usage is to conduct key inspections and timely maintenance, with a maintenance cycle of six months.

[0048] If δ > 3, the recommended usage is to discontinue use.

[0049] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0050] 1. The present invention provides a method for detecting and evaluating the operational status of concrete supports, which is a complete evaluation system including appearance inspection, concrete strength determination, finite element analysis, prestress fitting, bending moment calculation, and evaluation decision-making. It realizes the quantitative assessment of the remaining bearing capacity of the supports and provides clear maintenance suggestions, thus ensuring the safe operation of the electrified railway catenary system.

[0051] 2. The present invention provides a method for detecting and evaluating the operational status of concrete pillars. By using a refined rating system based on appearance zoning, the method converts indicators such as crack length, width, and exposed reinforcement quantity into quantifiable damage coefficients, thereby avoiding the subjectivity of human experience-based judgment.

[0052] 3. The present invention provides a method for detecting and evaluating the operational status of concrete pillars. It uses the rebound method to determine the concrete strength without the need for core drilling, thus achieving non-destructive testing. At the same time, it combines the prestress loss fitting with the exponential decay function to reflect the true decay law of prestress over time, making the structural resistance calculation more accurate.

[0053] 4. The present invention provides a method for detecting and evaluating the operational status of concrete pillars. By using finite element analysis to find the most unfavorable section and combining it with the structural resistance limit to calculate the capacity margin, it provides clear maintenance cycle recommendations, enabling the detection results to directly guide operation and maintenance decisions. Attached Figure Description

[0054] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0055] Figure 1 This is an overall flowchart of the present invention;

[0056] Figure 2 This is a schematic diagram of the support partition of the present invention;

[0057] Figure 3 This is a diagram showing the arrangement of rebound measuring points in this invention.

[0058] Figure 4 This is a concrete model diagram of the support column of the present invention;

[0059] Figure 5 This is a model diagram of the prestressed steel reinforcement of the present invention;

[0060] Figure 6 This is a diagram showing the most unfavorable cross-sectional position of the support column of the present invention;

[0061] Figure 7 This is a fitting graph of the exponential decay function of this invention;

[0062] Figure 8 This is the most unfavorable cross-sectional view. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and marked in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0064] In the description of the embodiments of this application, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] The following is combined with Figures 1-8 The present invention will be described in detail below.

[0066] Example 1

[0067] A method for detecting and evaluating the operational status of concrete pillars, such as Figures 1-8 The steps shown are as follows:

[0068] S1: Divide the support into sections, rate the condition of each section, take the section with the lowest rating as the overall appearance damage evaluation level and obtain the damage coefficient.

[0069] In this embodiment, as Figure 2 As shown, in S1, the support is divided into three sections: section I, section II, and section III. Section II is the ventral opening section, and section II is further divided into eleven units, each represented by a different unit. This indicates that each unit includes one borehole. Section I, located from the upper end of the borehole area to the top of the support, mainly bears the load transmitted from above. Section II, located in the borehole area, is a stress concentration and crack-prone area due to the presence of several boreholes. Section III, located from the lower end of the borehole to the bottom of the support, bears greater pressure and bending moment. The borehole area is further subdivided into units because damage between adjacent boreholes may occur independently. Refining to the unit level allows for precise location of which specific borehole has cracked or exposed reinforcement, thus forming a progressively focused and refined evaluation.

[0070] The rating of each segment in S1 includes:

[0071] Each unit is rated based on the presence of cracks and exposed reinforcement.

[0072] Each segment rating is obtained based on the rating results of each unit.

[0073] In this embodiment, the unit rating includes:

[0074] Grade A: The cross web and flanges of the column are free of cracks and exposed rebar;

[0075] Grade B: Cracks exist in the transverse web, but no cracks exist in the flanges, and the length of the transverse crack is less than or equal to the width of the support column. Or the length of the vertical crack is less than or equal to the width of the support column. The crack width is ≤0.3mm, or the transverse web is damaged or the exposed steel bars are ≤2, and the exposed length is ≤400mm, and there are no exposed steel bars on the flange;

[0076] Grade C: Cracks exist in the transverse web, but no cracks are found in the flanges, and the length of the transverse crack is greater than the width of the support column. Or the length of the vertical crack is greater than the width of the support column. And the crack width is ≤0.3mm, or the transverse web is damaged or there are more than 2 but less than or equal to 4 exposed steel bars, and the exposed length is ≤400mm, and there are no exposed steel bars or damage on the flange;

[0077] Grade d: The width of the crack in the transverse web is greater than 0.3 mm or there is a crack in the flange, or the transverse web is damaged or there are more than 4 exposed steel bars with a length greater than 400 mm.

[0078] Crack length, width, and the number and length of exposed reinforcement bars are the most direct and quantifiable indicators for measuring the degree of appearance damage, and they are easy to measure on site. Cracks are divided into transverse cracks and vertical cracks. Transverse cracks mainly affect the bending load-bearing capacity, while vertical cracks affect the shear resistance. The dimensions can be determined by on-site personnel using measuring tools.

[0079] In this embodiment, the segment rating includes:

[0080] Grade A: No Grade C units are rated, and the number of Grade B units is ≤20%;

[0081] Grade B: No Grade C in the unit rating, and the number of Grade Bs > 20%; or there are Grade Cs in the unit rating, and the number of Grade Cs ≤ 20%.

[0082] Grade C: There are Grade C units in the unit rating, and the number of Grade C units is greater than 20%;

[0083] Grade D: Unit rating includes a grade D;

[0084] The damage coefficient is 1 for grade A, 0.9 for grade B, and 0.83 for grade C. The damage coefficient value is determined by the section evaluation level, and recommendations are provided as follows:

[0085] The evaluation level is A, and the damage coefficient is... =1, which has virtually no impact on strength, and normal maintenance and inspection recommendations are given;

[0086] The evaluation level is B, and the damage coefficient is [missing information]. =0.9, which has little impact on strength; timely repair and enhanced inspection are recommended.

[0087] The evaluation level is C, and the damage coefficient is [missing information]. =0.83, the impact on strength is that the deterioration continues, and it is recommended to strengthen the inspection and take reinforcement measures when necessary;

[0088] A rating of D indicates that the product is at risk of being used, and a recommendation to discontinue its use is given.

[0089] S2: Select multiple rebound test areas in each section to determine the concrete strength;

[0090] In S2, such as Figure 3 As shown, two rebound testing areas were selected on the flange of section I, four on the flange of section II, and two on the flange of section III, with 16 testing points arranged within each rebound testing area. In this embodiment, the area of ​​each rebound testing area is 200mm × 200mm. The number and location of the rebound testing areas are based on the stress conditions and damage probabilities of different parts of the support. In section II, due to the presence of the ventral opening, pressure concentration is likely to occur, so four testing areas are set up to allow for more dense testing. In sections I and II, the stress conditions are relatively simple, so two testing areas are arranged in each section.

[0091] Determining the concrete strength includes: obtaining rebound values ​​from 16 measuring points within each rebound test area using the rebound method; discarding the three maximum and three minimum values; taking the average of the remaining 10 rebound values ​​as the representative rebound value for that test area; and using the minimum value from the eight rebound test areas as the ultimate strength of the support column. Discarding the three maximum and three minimum values ​​is a commonly used method for handling outliers. The average of the remaining 10 values ​​represents the average strength level of the test area. The calculation formula is as follows:

[0092]

[0093] In the formula, For the ultimate strength of the support column, The first in the same rebound test area One rebound value.

[0094] S3: Establish the finite element model of the support column, apply the preset load, and determine the location of the most unfavorable section.

[0095] S3 includes:

[0096] S3.1: Establish concrete and prestressed steel reinforcement models, set concrete plastic damage parameters, apply initial prestress to the prestressed tendons, and apply column base constraints.

[0097] S3.2: The location of the most unfavorable section is determined by the point where the stress changes abruptly in the cross section through finite element calculation.

[0098] In this embodiment, the column base constraint is as follows: the column is buried underground from a height of 3.5m below the bottom, therefore it is considered as a consolidation; the concrete uses a C3D8R grid, and the reinforcement uses linear subdivision; before setting the concrete plastic damage parameters, the concrete elastic modulus E is first set, and E=34500Mpa, corresponding to a Poisson's ratio of 0.2. The concrete plastic damage parameters include an expansion angle of 40° and an eccentricity of 0.1. =1.16, k=0.6667, viscosity parameter is 0.002, resulting in the following... Figure 4 The concrete model of the support column shown has a maximum stress of 30.56 MPa; the prestressed steel bars use spiral ribbed steel wire with a nominal diameter of 5.00 mm and a standard strength value of 1570 N / mm². 2 The tension control should be 840 N / mm. 2 The structural reinforcement uses 5mm cold-rolled steel bars with reinforcing strips, while the reinforcement for the cup-shaped foundation and chuck uses HPB235 steel, resulting in the following: Figure 5 The prestressed steel reinforcement model shown has a maximum stress of 618.37 MPa; from this, the location of the most unfavorable section can be obtained, such as... Figure 6 As shown, the most unfavorable section of the support is located at the lower end of the last spandrel, and the dimensions of the most unfavorable section are shown in the figure below. Figure 8 As shown.

[0099] Furthermore, in this embodiment, it should be noted that there are four most unfavorable cross sections under different working conditions, namely:

[0100] Condition 1: When the wind direction is perpendicular to the line, the bearing capacity of the support column in the suspension direction and the load borne by the support column are composed of the suspension load and the bending moment of the support column wind load. The soft cross-span support column also includes the additional bending moment in the direction parallel to the line generated by the 3° deflection angle.

[0101] Condition 2: When the wind direction is parallel to the line, the bearing capacity of the support column in the suspension direction and the load borne by the support column are composed of the suspension load in the direction perpendicular to the line and the wind load and cantilever wind load in the direction parallel to the line. The soft cross-span support column also includes the additional bending moment in the direction parallel to the line generated by the 3° deflection angle.

[0102] Operating Condition 3: Bearing capacity of the support in the opposite suspension direction when the wind direction is perpendicular to the line;

[0103] Condition 4: Bearing capacity of parallel track supports under no suspended surface load.

[0104] S4: Fit the prestress loss value of the prestressed tendon using an exponential decay function.

[0105] In this embodiment, the fitting formula is as follows:

[0106]

[0107] In the formula, Time, in years; The concrete decay time constant, such as Figure 7 As shown, the prestress loss in prestressed steel bars decreases according to the curve within 0-2 years, with τ being 0.40805. After 2 years, it tends to stabilize, with a decrease of about 20%-30%.

[0108] S5: Calculate the bending moment of the most unfavorable section based on the damage coefficient, ultimate strength and prestress loss value, and calculate the support capacity margin based on the calculated bending moment and the design value, and determine the maintenance recommendation based on the capacity margin.

[0109] In this embodiment, the most unfavorable cross-section determined by S3.2 has the following geometric dimensions, including the web width. Effective height of cross section These parameters will be directly used as the basic input parameters for bending moment calculation in S5, and the bending moment at the most unfavorable section will be calculated, including the bending moment in the direction perpendicular to the track and in the direction along the track.

[0110] In this embodiment, the initial prestress is 840 MPa, and it is applied along the Y direction of the steel bar, with zero stress in the X and Z directions. The column base is anchored in a completely fixed manner, and the failure section of the column is obtained by displacement loading.

[0111] Furthermore, in this embodiment, the bending moment in the direction perpendicular to the track... The calculation formula is as follows:

[0112]

[0113]

[0114] In the formula, This is the margin for the bending moment of the support column in the direction perpendicular to the track. This is the design value for the bending moment of the support column in the direction perpendicular to the track.

[0115] In this embodiment, >3 indicates that the recommended usage is normal and the maintenance cycle is 3 years;

[0116] 2.5 < ≤3 indicates that the recommended use is to increase inspections and the maintenance cycle is 1 year;

[0117] 2< If the value is ≤2.5, the recommended usage is to conduct key inspections and timely maintenance, with a maintenance cycle of six months.

[0118] >3, the recommended usage is to exit the service.

[0119] In the formula, Damage coefficient; It is a coefficient and takes a value of 1.0; This refers to the ultimate strength of concrete. The web width is the most unfavorable section. This refers to the height of the concrete compression zone. The effective height of the cross-section; The prestressing tendon stress is the stress of the prestressing tendon when the normal stress of the concrete at the resultant point of the prestressing tendon in the compression zone is zero. This is the design value for the prestressed tendons in the tension zone, and it is taken as 1570 MPa. This is the design value for the prestressed tendons in the compression zone, and it is taken as 1570 MPa. This represents the prestress loss value; This represents the cross-sectional area of ​​the longitudinal prestressing tendons in the compression zone; The distance from the resultant point of the longitudinal prestressing tendons in the compression zone to the compression edge of the section is taken as 25mm;

[0120] bending moment in the direction of the line The calculation formula is as follows:

[0121]

[0122]

[0123] In the formula, This represents the cross-sectional area of ​​the longitudinal prestressing tendons in the compression zone; This is the margin for the bending moment of the support along the track direction. This refers to the design value of the bending moment of the support along the track direction. It should also be noted that... , All values ​​are known. , It is obtained through calculation, therefore it can be calculated. , This allows you to obtain usage suggestions.

[0124] In this embodiment, >3 indicates that the recommended usage is normal and the maintenance cycle is 3 years;

[0125] 2.5 < ≤3 indicates that the recommended use is to increase inspections and the maintenance cycle is 1 year;

[0126] 2< If the value is ≤2.5, the recommended usage is to conduct key inspections and timely maintenance, with a maintenance cycle of six months.

[0127] >3, the recommended usage is to exit the service.

[0128] In this embodiment, calculations are performed using three types of electrified railway catenary concrete supports: H78, H93, and H170. First, the most unfavorable cross-section is found using finite element analysis. Figure 8 As shown, according to Figure 8 For medium-sized columns, the bending moments along and perpendicular to the track direction of the support were calculated using structural resistance limits, as shown in Tables 1 and 2. These tables represent the bending moments of columns at H60, H78, and H170, respectively, under an evaluation level of C. In this embodiment, the most unfavorable section of the support is located below the opening, where the force abruptly changes, causing the concrete compression section to shrink. This stress abrupt change leads to section failure, with the failure section approximately 3.8m from the bottom of the foundation. The following diagrams are also provided. Figure 8 The most unfavorable cross-sectional dimensions are shown below;

[0129] Table 1. Bending moment in the vertical direction of Class C damage.

[0130]

[0131] Table 2. Class C Damage: Bending Moment Along the Track Direction

[0132]

[0133] In this embodiment, by introducing an appearance-based rating method, the support column is divided into multiple sections for separate scoring, thereby more accurately determining the specific damage location and obtaining a more accurate damage coefficient. In S2, the concrete strength is determined by the rebound method. The rebound method is a method that uses a rebound hammer to impact the concrete surface and estimates the compressive strength of the concrete based on the rebound value. This is an existing technology. In this invention, by arranging multiple rebound test areas in each section, the weaker parts can be captured more accurately. In S3, a concrete and prestressed tendon model is established according to the actual size of the support column. By applying a predetermined load and performing finite element calculations, the weak points of the support column section stress can be accurately found. In S4, the prestressed tendons will experience stress loss due to factors such as steel relaxation and concrete shrinkage and creep during long-term use. The rate of stress loss follows a pattern of rapid initial loss followed by gradual decrease over time. The exponential decay function can precisely describe this trend, thereby providing accurate prestress parameters for subsequent calculations. Therefore, through the above S1-S5, this invention forms a complete evaluation system including appearance inspection, concrete strength determination, finite element analysis, prestress fitting, bending moment calculation, and evaluation decision-making, thereby achieving an accurate assessment of the support column condition.

[0134] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting and evaluating the operational status of concrete pillars, characterized in that, Includes the following steps: S1: Divide the support into sections, rate the condition of each section, take the section with the lowest rating as the overall appearance damage evaluation level and obtain the damage coefficient. S2: Select multiple rebound test areas in each section to determine the concrete strength; S3: Establish the finite element model of the support column, apply the preset load, and determine the location of the most unfavorable section. S4: Fit the prestress loss value of the prestressed tendon using an exponential decay function; S5: Calculate the bending moment of the most unfavorable section based on the damage coefficient, ultimate strength and prestress loss value, and calculate the support capacity margin based on the calculated bending moment and the design value, and determine the maintenance recommendation based on the capacity margin.

2. The method for detecting and evaluating the operational status of concrete supports according to claim 1, characterized in that, In S1, the support is divided into three sections: section I, section II, and section III. Section II is the ventral opening section, and section II is further divided into multiple units, each of which includes a ventral opening.

3. The method for detecting and evaluating the operational status of concrete pillars according to claim 2, characterized in that, The rating of each segment in S1 includes: Each unit is rated based on the presence of cracks and exposed reinforcement. Each segment rating is derived based on the rating results of each unit.

4. The method for detecting and evaluating the operational status of concrete pillars according to claim 3, characterized in that, The unit rating includes: Grade A: The cross web and flanges of the column are free of cracks and exposed rebar; Grade B: Cracks exist in the transverse web, but no cracks exist in the flanges, and the length of the transverse crack is less than or equal to the width of the support column. Or the length of the vertical crack is less than or equal to the width of the support column. The crack width is ≤0.3mm, or the transverse web is damaged or the exposed steel bars are ≤2, and the exposed length is ≤400mm, and there are no exposed steel bars in the flange; Grade C: Cracks exist in the transverse web, but no cracks are found in the flanges, and the length of the transverse crack is greater than the width of the support column. Or the length of the vertical crack is greater than the width of the support column. And the crack width is ≤0.3mm, or the transverse web is damaged or there are more than 2 but less than or equal to 4 exposed steel bars, and the exposed length is ≤400mm, and there are no exposed or damaged steel bars in the flange; Grade d: The width of the crack in the transverse web is greater than 0.3 mm or there is a crack in the flange, or the transverse web is damaged or there are more than 4 exposed steel bars with a length greater than 400 mm.

5. The method for detecting and evaluating the operational status of concrete pillars according to claim 3, characterized in that, The segment rating includes: Grade A: No Grade C units are rated, and the number of Grade B units is ≤20%; Grade B: No Grade C in the unit rating, and the number of Grade Bs > 20%; or there are Grade Cs in the unit rating, and the number of Grade Cs ≤ 20%. Grade C: There are Grade C units in the unit rating, and the number of Grade C units is greater than 20%; Grade D: Unit rating includes a grade D; The injury coefficient for Grade A is 1, for Grade B it is 0.9, and for Grade C it is 0.

83.

6. The method for detecting and evaluating the operational status of concrete pillars according to claim 3, characterized in that, In S2, two rebound test areas are selected on the flange of section I, four rebound test areas are selected on the flange of section II, and two rebound test areas are selected on the flange of section III, with 16 test points arranged in each rebound test area.

7. The method for detecting and evaluating the operational status of concrete pillars according to claim 4, characterized in that, Determining the concrete strength includes: obtaining the rebound values ​​of 16 measuring points in each rebound test area using the rebound method, removing the three maximum and minimum values ​​respectively, taking the average of the remaining 10 rebound values ​​as the representative rebound value of the rebound test area, and taking the minimum value of the 8 rebound test areas as the ultimate strength of the column.

8. The method for detecting and evaluating the operational status of concrete pillars according to claim 5, characterized in that, S3 includes: S3.1: Establish concrete and prestressed steel reinforcement models, set concrete plastic damage parameters, apply initial prestress to the prestressed tendons, and apply column base constraints. S3.2: The location of the most unfavorable section is determined by the point where the stress changes abruptly in the cross section through finite element calculation.

9. The method for detecting and evaluating the operational status of a concrete support column according to claim 6, characterized in that, In S5, the calculation of the bending moment at the most unfavorable section includes the calculation of the bending moment in the direction perpendicular to the track and in the direction along the track.

10. The method for detecting and evaluating the operational status of a concrete support column according to claim 6, characterized in that, According to the capacity margin The maintenance recommendations include: The recommended usage is normal, and the maintenance cycle is 3 years. The recommended use is to increase inspections, and the maintenance cycle is 1 year. The recommended usage is to conduct key inspections and timely maintenance, with a maintenance cycle of six months. The recommended usage is to exit the service.

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