Adaptability and reliability analysis method of bridge reinforcement scheme

Abstract

The present invention discloses an adaptability and reliability analysis method for a bridge reinforcement scheme, comprising: step 1, selecting multiple primary indicators for evaluating the reinforcement scheme and multiple quantifiable secondary indicators reflecting each primary indicator according to the bridge type to be reinforced; step 2, subjectively assigning weights to each primary indicator according to engineering experience, and the sum of the weights of all primary indicators is 1; step 3, the value and weight of each secondary indicator are calculated based on historical detection data; step 4, calculating the adaptability evaluation value of each reinforcement scheme; step 5, selecting the reinforcement scheme with the largest adaptability evaluation value. The present invention has the beneficial effects of conducting adaptability analysis and evaluation on bridge reinforcement schemes, providing data support for the selection of reinforcement schemes, and assisting decision-makers in screening bridge reinforcement schemes.

Description

Technical Field

[0001] The present invention relates to the field of bridge reinforcement technology analysis, and more specifically, to a method for analyzing the adaptability and reliability of a bridge reinforcement scheme. Background Art

[0002] The purpose of bridge reinforcement is to improve the safety of bridge structures and extend their service life. Commonly used bridge maintenance and reinforcement technologies can be divided into three categories: bridge surface repair technology, bridge reinforcement technology, and bridge repair and reconstruction technology. Among them, bridge surface repair technology includes four categories: crack injection, crack sealing, defect repair, and bridge anti-corrosion; bridge reinforcement technology includes four categories: steel plate bonding, composite fiber bonding, cross-section enlargement, and external prestressed reinforcement. Bridge repair and reconstruction technologies include bridge deck pavement reconstruction, replacement of expansion joints and bearings, replacement of beams and slabs, replacement of hangers, and addition of pile foundations. Choosing the appropriate reinforcement method for a specific project at a specific time is the focus of managers' decision-making. At present, there is no patent for the adaptability and reliability evaluation of bridge reinforcement effects. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] Another object of the present invention is to provide an adaptability and reliability analysis method for a bridge reinforcement scheme, which can perform adaptability analysis and evaluation on the bridge reinforcement scheme, provide data support for the selection of reinforcement schemes, and assist decision-makers in screening bridge reinforcement schemes.

[0005] In order to achieve these purposes and other advantages according to the present invention, a method for analyzing the adaptability and reliability of a bridge reinforcement scheme is provided, comprising the following steps:

[0006] Step 1: According to the type of bridge to be reinforced, select multiple primary indicators for evaluating the reinforcement scheme and multiple quantifiable secondary indicators reflecting each primary indicator;

[0007] Step 2: Subjectively assign weights to each first-level indicator, and the sum of the weights of all first-level indicators is 1;

[0008] Step 3: The value and weight of each secondary indicator are calculated based on historical test data. The specific method is as follows: select multiple groups of historical test data with the same bridge type as the bridge to be reinforced, calculate the value of the secondary indicator based on each group of historical test data, and calculate the mean and variance of multiple groups of the same secondary indicator, and calculate the weight of each secondary indicator under the same primary indicator based on the mean of the secondary indicator;

[0009] Then, the mean and variance of each secondary indicator are set to conform to the normal distribution, multiple samples are randomly selected from the normal distribution, and the mean of the secondary indicators of the multiple samples is calculated as the value of the secondary indicator at that time;

[0010] Step 4: Calculate the adaptability evaluation value of each reinforcement scheme. The specific method is as follows: calculate the weighted sum of multiple secondary indicators under the same primary indicator based on the value and weight of the secondary indicator to obtain the value of the primary indicator, and then calculate the weighted sum of multiple primary indicators based on the value and weight of the primary indicator to obtain the adaptability evaluation value;

[0011] Step 5: Compare and select the reinforcement scheme with the largest adaptability evaluation value.

[0012] Preferably, the primary indicators include safety indicators and efficiency indicators.

[0013] Preferably, the safety index includes: load capacity improvement rate P u , Component reinforcement percentage P s , reinforcement frequency F s ,in,

[0014] Carrying capacity improvement rate

[0015] Among them, P b is the bearing capacity before reinforcement, P a is the bearing capacity after reinforcement;

[0016] Component reinforcement percentage

[0017] Among them, n b is the total number of components, n a The number of unreinforced components

[0018] Reinforcement frequency F s :

[0019] Among them, T i is the time interval between two reinforcements.

[0020] Preferably, the efficiency index includes: reinforcement duration T s , Construction difficulty coefficient L s , Ratio of reinforcement cost to extended service life ρ m ;

[0021] Among them, the reinforcement duration refers to the total time required from the beginning to the completion of the bridge reinforcement using the reinforcement scheme;

[0022] The construction difficulty coefficient is 1 for the most difficult reinforcement scheme, and the construction difficulty coefficients of other reinforcement schemes are between 0 and 1;

[0023] Ratio of reinforcement cost to extended service life ρ m :

[0024] Among them, M i For reinforcement cost investment, T c is the normal service life after reinforcement, T b It is the normal service life when no reinforcement measures are taken.

[0025] Preferably, the method for assigning the construction difficulty coefficient is as follows: list all available reinforcement schemes and arrange them in order of construction difficulty from difficult to easy, with the most difficult construction difficulty coefficient being 1 and the least difficult construction difficulty coefficient being 0. The construction difficulty coefficients of other reinforcement schemes are assigned using linear interpolation.

[0026] Preferably, the reinforcement scheme includes: a steel plate bonding reinforcement scheme, a composite fiber bonding reinforcement scheme, a cross-section enlargement reinforcement scheme, and an external prestressed reinforcement scheme.

[0027] Preferably, a dimensionless method is used to process the mean and variance of the secondary index.

[0028] Preferably, the weights of the secondary indicators are calculated using the entropy method.

[0029] Preferably, the bridge types include: suspension bridge, arch bridge, and continuous beam bridge.

[0030] The present invention includes at least the following beneficial effects: the analysis method of the present invention can perform adaptability analysis and evaluation on bridge reinforcement schemes, provide data support for the selection of reinforcement schemes, and assist decision-makers in screening bridge reinforcement schemes.

[0031] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flowchart of the analysis method according to one of the technical solutions of the present invention;

[0033] Figure 2 A diagram showing the calculation results of a safety index sampling of one of the technical solutions of the present invention;

[0034] Figure 3 A diagram showing the sampling calculation results of the efficiency index of one of the technical solutions of the present invention;

[0035] Figure 4A diagram showing the sampling calculation results of the adaptability evaluation value of one of the technical solutions of the present invention;

[0036] Figure 5 A frequency distribution diagram of safety indicators of a steel plate bonding reinforcement solution according to one of the technical solutions of the present invention;

[0037] Figure 6 This is a frequency distribution diagram of the safety index of the composite fiber reinforcement solution of one of the technical solutions of the present invention;

[0038] Figure 7 A frequency distribution diagram of the safety index of the enlarged cross-section reinforcement solution of one of the technical solutions of the present invention;

[0039] Figure 8 A frequency distribution diagram of safety indicators of an external prestressed reinforcement solution of one of the technical solutions of the present invention;

[0040] Fig. 9 This is a frequency distribution diagram of the efficiency index of the steel plate bonding reinforcement solution of one of the technical solutions of the present invention;

[0041] Fig.10 This is a frequency distribution diagram of efficiency indexes of a composite fiber bonding reinforcement solution of a technical solution of the present invention;

[0042] Fig.11 This is a frequency distribution diagram of the efficiency index of the enlarged cross-section reinforcement solution of one of the technical solutions of the present invention;

[0043] Fig.12 This is a frequency distribution diagram of the efficiency index of the external prestressed reinforcement solution of one of the technical solutions of the present invention;

[0044] Fig.13 It is a frequency distribution diagram of comprehensive indicators of a steel plate bonding reinforcement solution of one of the technical solutions of the present invention;

[0045] Fig.14 This is a frequency distribution diagram of comprehensive indicators of a composite fiber reinforcement solution of one of the technical solutions of the present invention;

[0046] Fig.15 It is a frequency distribution diagram of comprehensive indicators of a cross-section enlargement reinforcement solution of one of the technical solutions of the present invention;

[0047] Fig.16 A frequency distribution diagram of comprehensive indicators of an external prestressed reinforcement solution of one of the technical solutions of the present invention;

[0048] Fig.17 This is a comparison chart of the adaptability evaluation results of four reinforcement schemes of one of the technical solutions of the present invention. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0050] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the orientation or positional relationship indicated by the terms is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0051] like Figures 1 to 17 As shown, the present invention provides an adaptability and reliability analysis method for a bridge reinforcement scheme, comprising the following steps:

[0052] Step 1: According to the type of bridge to be reinforced, select multiple primary indicators for evaluating the reinforcement scheme and multiple quantifiable secondary indicators reflecting each primary indicator;

[0053] Step 2: Subjectively assign weights to each first-level indicator based on engineering experience, and the sum of the weights of all first-level indicators is 1;

[0054] Step 3: The value and weight of each secondary indicator are calculated based on historical test data. The specific method is as follows: select multiple groups of historical test data with the same bridge type as the bridge to be reinforced, calculate the value of the secondary indicator based on each group of historical test data, and calculate the mean and variance of multiple groups of the same secondary indicator, and calculate the weight of each secondary indicator under the same primary indicator based on the mean of the secondary indicator;

[0055] Then, the mean and variance of each secondary indicator are set to conform to the normal distribution, multiple samples are randomly selected from the normal distribution, and the mean of the secondary indicators of the multiple samples is calculated as the value of the secondary indicator at that time;

[0056] Step 4: Calculate the adaptability evaluation value of each reinforcement scheme. The specific method is as follows: calculate the weighted sum of multiple secondary indicators under the same primary evaluation indicator based on the value and weight of the secondary indicator to obtain the value of the primary indicator, and then calculate the weighted sum of multiple primary indicators based on the value and weight of the primary indicator to obtain the adaptability evaluation value of the reinforcement scheme.

[0057] Step 5: Compare and select the reinforcement scheme with the largest adaptability evaluation value.

[0058] When selecting a reinforcement scheme for a bridge, you can use the above technical solutions. First, after the bridge is determined, its bridge type is determined, and the bridge reinforcement requirements are determined, then the reinforcement schemes that can be used are also determined. Several optional ones, and then according to the reinforcement scheme, set the first-level indicators. Usually, the first-level indicators will use safety indicators and efficiency indicators. Then, according to the first-level indicators, select the second-level indicators that can be quantified and can reflect the performance of the first-level indicators for quantitative calculation, so that various schemes can be more objectively compared and screened. The safety indicator usually uses the load-bearing capacity improvement rate P. u , Component reinforcement percentage P s , reinforcement frequency F s The efficiency index is usually the reinforcement duration T s and construction difficulty coefficient L s .

[0059] Secondly, bridge designers, bridge experts and scholars, or decision makers usually set weights for each first-level indicator based on experience to reflect the importance of each first-level indicator. For the second-level indicators that can be quantified, the weights of each item are calculated using data statistical calculation methods, usually using the mean square error method, entropy method, and range method.

[0060] Finally, according to the weight of the first-level indicators, the value and weight of the second-level indicators, the weighted sum can be calculated, that is, the adaptability evaluation value of the reinforcement scheme. The larger the adaptability evaluation value, the better the reinforcement scheme. This can comprehensively evaluate the advantages and disadvantages of the reinforcement scheme and help decision makers make more accurate choices.

[0061] In another technical solution, the first-level indicators include: safety indicators and efficiency indicators.

[0062] To evaluate the pros and cons of a bridge reinforcement scheme, it is necessary to consider factors such as the extent of improvement in bridge safety, the frequency of reinforcement, the duration of reinforcement work, and the difficulty of construction. Therefore, safety and efficiency indicators are usually required to be taken into consideration.

[0063] In another technical solution, the safety index includes: load capacity improvement rate P u , Component reinforcement percentage P s , reinforcement frequency F s ,in,

[0064] Carrying capacity improvement rate

[0065] Among them, P b is the bearing capacity before reinforcement, P a is the bearing capacity after reinforcement;

[0066] Component reinforcement percentage

[0067] Among them, n b is the total number of components, n a The number of unreinforced components

[0068] Reinforcement frequency F s :

[0069] Among them, T i is the time interval between two reinforcements.

[0070] In the above technical solution, the bearing capacity improvement rate: The overall bearing capacity of the bridge depends on the stress conditions of its main components. The evaluation of the bearing capacity of the components requires comprehensive consideration of factors such as bending bearing capacity, shear bearing capacity, local stress concentration, and component integrity. Common bearing capacity assessment methods include empirical methods based on actual bridge surveys, load test methods, design theory methods, evaluation methods based on dynamic characteristics, and evaluation methods based on reliability theory. After the bridge is reinforced, the bearing capacity of the components will be improved to achieve the purpose of continued use. The bearing capacity improvement rate after reinforcement and before reinforcement reflects the degree of improvement in the safety of bridge components and can be used as a safety indicator for evaluating the adaptability analysis of reinforcement technology.

[0071] Component reinforcement percentage: A bridge is a complex entity composed of multiple components. The number of reinforced components reflects the safety of the bridge structure to a certain extent. The component reinforcement percentage is used here as an indicator to evaluate safety.

[0072] Reinforcement frequency: The frequency of component reinforcement reflects the time interval of bridge reinforcement and the safety effect of reinforcement. Generally speaking, after the bridge structure is reinforced for the first time, the greater the reinforcement frequency, the worse the safety. The reinforcement frequency is expressed by the number of reinforcements per year.

[0073] In another technical solution, the efficiency index includes: reinforcement duration T s , Construction difficulty coefficient L s , Ratio of reinforcement cost to extended service life ρ m ;

[0074] Among them, the reinforcement duration refers to the total time required for the reinforcement scheme to strengthen the bridge from start to completion;

[0075] The construction difficulty coefficient is 1 for the most difficult reinforcement scheme, and the construction difficulty coefficients of other reinforcement schemes are between 0 and 1;

[0076] Ratio of reinforcement cost to extended service life ρ m :

[0077] Among them, M i For reinforcement cost investment, Tc is the normal service life after reinforcement, T b It is the normal service life when no reinforcement measures are taken.

[0078] In the above technical solution, reinforcement duration: The reinforcement process of the existing bridge structure will not only affect the project cost, but also affect the traffic of vehicles. Therefore, the reinforcement duration is an efficiency indicator. The shorter the duration, the higher the efficiency.

[0079] Construction difficulty coefficient: The conventional construction process of commonly used bridge structure reinforcement technology is basically the same, and the difficulty of construction is predictable. We hope to choose a reinforcement method that is easy and simple and has simple construction quality control, but we should also pay attention to the reinforcement effect. Therefore, the construction difficulty is an efficiency indicator, and once the construction technology and method are determined, the construction difficulty is determined. The reinforcement method with difficult construction has poor efficiency. When determining the construction difficulty parameter, the construction difficulty of all reinforcement technologies is usually considered comprehensively, and the difficulty coefficient of the most difficult construction method is 1, and the other construction methods are between 0 and 1.

[0080] The purpose of bridge reinforcement is to extend the service life. The important task of the maintenance management unit is to use the maintenance funds efficiently, that is, to minimize the reinforcement cost per extended service life. The larger the ratio of reinforcement cost to extended service life, the lower the reinforcement efficiency of the method. Therefore, the ratio of bridge reinforcement cost to extended service life is an efficiency indicator.

[0081] In another technical solution, the method for assigning the construction difficulty coefficient is as follows: all available reinforcement schemes are listed and arranged in order of construction difficulty from difficult to easy. The most difficult construction difficulty coefficient is 1, and the least difficult construction difficulty coefficient is 0. The construction difficulty coefficients of other reinforcement schemes are assigned using linear interpolation.

[0082] Linear interpolation is a method of approximating the values ​​of an unknown function based on a set of known independent variables and their corresponding function values, using geometric relationships to find the approximate values ​​of other unknown functions. It is a method of finding the approximate value of an unknown function.

[0083] In another technical solution, the reinforcement solutions include: steel plate bonding reinforcement solution, composite fiber bonding reinforcement solution, cross-section enlargement reinforcement solution, and external prestressed reinforcement solution.

[0084] Among the above technical solutions, conventional bridge reinforcement solutions are usually the above four. Bonding steel plates refers to using the tensile strength of the steel plates themselves to bond them to the weak tensile parts of the concrete structure through structural adhesives, so that they form a whole with the structure, improve the overall stress performance of the structure, and extend the service life of the structure. The application scenarios of bonding steel plates include: 1) Insufficient bending resistance; 2) Insufficient shear resistance; 3) Local stress concentration; 4) Insufficient reinforcement; 5) Integrity deviation.

[0085] Bonding composite fibers means bonding high-strength fiber sheets to the surface of structural components with impregnated resins. After curing, a composite structure with a fiber-reinforced effect is formed, thereby improving the tensile strength or restraint of the component to achieve the purpose of reinforcement. Composite fiber sheets exhibit a linear elastic relationship when stretched until they are damaged, and their brittle properties are significantly different from the ductility of steel bars. Common scenarios for bonding composite fiber cloth include: 1) reinforcement of small components; 2) reinforcement of areas with complex stresses; 3) axially compressed components.

[0086] The method of increasing the cross-section reinforcement refers to using the same material - reinforced concrete to increase the structural size on the surface of the component, increase the load-bearing steel bars, and make it form an integral whole with the original structure, thereby increasing the effective height of the component and the area of ​​the load-bearing steel bars, increasing the stiffness of the component, and improving the overall bearing capacity of the bridge to achieve the purpose of reinforcement. Common scenarios for the method of increasing the cross-section reinforcement include: 1) arch ring reinforcement; 2) pier column reinforcement; 3) T-beam reinforcement; 4) box beam reinforcement.

[0087] External prestressing is one of the important branches of post-tensioning prestressing system. Different from the traditional post-tensioning bonded or unbonded prestressed structure, the external prestressing structure is a structural system in which the prestressing beams are arranged outside the main section of the structure to apply prestress.

[0088] In another technical solution, a dimensionless method is used to process the means and values ​​of the secondary indicators.

[0089] Since the dimensions and magnitudes of the secondary indicators are different, it is impossible to conduct comprehensive analysis and calculation. Therefore, the secondary indicators need to be dimensionless. In order to facilitate the hierarchical processing of the constructed original matrix and evaluation results for evaluation, it is necessary to make the value of each dimensionless parameter belong to (0, 1]. The dimensionless method used here is as follows:

[0090] In the evaluation system with n adaptability evaluation objects and m evaluation indicators, the original matrix constructed for evaluation is an m×n matrix, where each element x ij is the evaluation data of the jth indicator of the ith object, then the dimensionless evaluation data can be expressed as

[0091]

[0092] Among them, max[x j] is the maximum value of the evaluation data of the jth indicator.

[0093] In another technical solution, the weights of the secondary indicators are calculated using the entropy method.

[0094] In the above technical solution, for a given j-th indicator, the dimensionless evaluation data x i ' j The greater the difference, the greater the comparative effect of the secondary indicator on the evaluated scheme, that is, the more information the secondary indicator contains and transmits.

[0095] Under the jth secondary indicator, the characteristic weight of the i-th solution can be expressed as:

[0096]

[0097] The entropy value of the j-th secondary indicator is:

[0098]

[0099] The coefficient of difference of the jth indicator is:

[0100] g j =1-e j Formula 8

[0101] The weight of the jth indicator is:

[0102]

[0103] In another technical solution, the bridge types include: suspension bridge, arch bridge, and continuous beam bridge.

[0104] In summary, the formula for expressing the primary index, secondary index and adaptability evaluation value is as follows:

[0105] The safety index S and the efficiency index E are defined as primary indexes. The weights of primary indexes are usually determined by subjective weighting method. The weights of secondary indexes are determined by entropy method. For a given j (the jth index), the dimensionless evaluation data x′ ij The greater the difference, the greater the comparative effect of the indicator on the evaluated reinforcement schemes, that is, the more information the indicator contains and transmits.

[0106] By calculating the weight vectors of the safety index and the efficiency index respectively, we can get W1=(ω′1, ω′2, ω′3) T ,

[0107] W2=(ω″1,ω″2,ω″3) T ;

[0108] According to the weights of the secondary indicators and the dimensionless indicator values, the evaluation values ​​of the primary indicators can be obtained as follows:

[0109] S=W1(p u , p s , F s ) T Formula 10

[0110] E=W2(T s , L s , ρ m ) T Formula 11

[0111] According to the values ​​of the above-mentioned secondary indicators, if the weights of the primary indicators are λ1 and λ2 respectively, the adaptability evaluation value Z can be obtained. The scheme with the largest adaptability evaluation value is the optimal scheme, that is, the scheme with the best adaptability.

[0112] Z=λ1S+λ2E Formula 12

[0113] The present invention mainly conducts adaptability and reliability analysis on bridge reinforcement schemes. The proposed analysis method can be extended to bridge surface repair technology and bridge repair and reconstruction technology, and even to the adaptability analysis of other types of infrastructure. Adaptability and reliability analysis is to select specific evaluation indicators based on existing data or information, combined with the technical characteristics of bridge reinforcement itself, and after comprehensive analysis, to obtain the advantages and disadvantages of various reinforcement schemes at different reinforcement times, and finally determine and recommend the best reinforcement scheme to achieve the best reinforcement effect in terms of safety and economy.

[0114] <Example>

[0115] Taking the commonly used reinforcement schemes for concrete bridge structures as an example, this paper describes the selection of adaptability evaluation parameters (primary indicators, secondary indicators), weight determination, secondary indicator sampling, and adaptability analysis and calculation results.

[0116] 1. Selection of adaptability evaluation parameters (primary indicators and secondary indicators)

[0117] Taking the four types of bridge reinforcement methods, namely, bonding steel plates, bonding composite fibers, increasing cross-sections, and external prestressed reinforcement, as the analysis objects, the safety index and efficiency index of various reinforcement methods were determined respectively (the safety index and efficiency index are primary indexes).

[0118] Bonding steel plates refers to using the tensile strength of steel plates to bond them to the weak tensile position of concrete structures through structural adhesives, so that they can form an integral part with the structure, improve the overall stress performance of the structure, and extend the service life of the structure. Application scenarios of bonding steel plates include: 1) Insufficient bending resistance; 2) Insufficient shear resistance; 3) Local stress concentration; 4) Insufficient reinforcement; 5) Integrity deviation.

[0119] Pasting composite fiber means pasting high-strength fiber sheets on the surface of structural components with impregnated resin, and forming a composite structure with fiber reinforcement effect after curing, so as to improve the tensile strength or constraint of the components and achieve the purpose of reinforcement. Composite fiber sheets are linear elastic when tensile until they are destroyed, and their brittle properties are significantly different from the ductility of steel bars. The ductility of the structure after reinforcement will be limited, and the stress redistribution in the components will be constrained. Therefore, carbon fiber sheets cannot be simply used as a substitute for steel bars. The brittle characteristics of carbon fiber sheets must be considered. The degree of tensile strength of carbon fiber cloth depends on the deformation of the reinforced bending member, so the improvement of the bending resistance of the structure is limited. However, since the construction of pasting carbon fiber is simple and fast, it does not increase the weight of the original structure, does not affect the appearance of the structure, and can restrict the development of cracks, it indirectly improves the crack resistance of the structure, and also plays a certain role in improving the corrosion resistance and carbonization resistance of concrete. It is currently widely used in engineering. Common scenarios for pasting composite fiber cloth include: 1) reinforcement of small components; 2) reinforcement of complex stress parts; 3) axially compressed components.

[0120] The method of increasing the cross-section reinforcement refers to using the same material - reinforced concrete to increase the structural size on the surface of the component, increase the stressed steel bars, and make it form a whole with the original structure, thereby increasing the effective height of the component and the area of ​​the stressed steel bars, increasing the stiffness of the component, and improving the overall bearing capacity of the bridge to achieve the purpose of reinforcement. This method of reinforcement has mature design and rich construction experience, relatively low engineering cost, simple construction process, and wide application. It can be used for the reinforcement of various concrete structures such as T-beams, box girders, piers and general structures. The reinforcement effect is more significant. The disadvantage is that the workload of on-site wet operations is large, the maintenance period is long, and the cross-sectional size is affected. Common scenarios for the method of increasing the cross-section reinforcement include: 1) arch ring reinforcement; 2) pier reinforcement; 3) T-beam reinforcement; 4) box girder reinforcement.

[0121] External prestressing is one of the important branches of post-tensioning prestressing system. Different from the traditional post-tensioning bonded or unbonded prestressed structure, the external prestressing structure is a structural system in which the prestressing beams are arranged outside the main section of the structure to apply prestress.

[0122] External prestressing technology is used in the field of old bridge reinforcement. It has many advantages, such as clear force, simple construction, light weight, obvious improvement of structural stress conditions, convenient maintenance and repair, and less damage to the original bridge structure. Generally speaking, the main application scenarios of external prestressing include: 1) It is suitable for situations where the beam deflection exceeds the specification due to insufficient bending stiffness of beam bridges or the crack width in the tensile zone of the beam exceeds the specification due to too small stiffness; 2) It is suitable for situations where the arch crown of the arch bridge sinks or the pier's anti-thrust capacity is insufficient. 3) It is suitable for reinforcement after cracks in local bridge components.

[0123] Through the above analysis, by comparing the safety and effectiveness of the above four reinforcement schemes, we can derive the various comfort evaluation indicators of the four reinforcement schemes: gluing steel plates, gluing composite fibers, increasing cross-sections, and external prestressing reinforcement. Under normal circumstances, based on engineering experience and accumulated test data, the values ​​of the bearing capacity improvement rate during component reinforcement, component reinforcement percentage, reinforcement frequency, reinforcement duration, construction difficulty coefficient, and reinforcement cost to extension ratio can be obtained. However, due to the vast territory of our country and different climate and other conditions, the parameters will be slightly different. In order to reasonably consider the safety and efficiency indicators of bridges in different regions, different bridge types, and different conditions, it is assumed that each adaptability evaluation parameter obeys a normal distribution, and its mean is determined by experience and accumulated test data, and the variance is used to consider uncertain factors such as regional differences. The determined parameters of each indicator of the bridge structure are shown in the following table:

[0124] Table 1 Adaptability analysis index parameter table

[0125]

[0126] 2. Determination of weights

[0127] For bridge reinforcement, safety and efficiency are equally important, so the weights of the safety index and the efficiency index are both subjectively assigned to 0.5.

[0128] According to the average values ​​of the secondary indicators of the above safety index and efficiency index, the weights of each secondary indicator are calculated according to formulas 6, 7, 8, and 9: the weights of the three safety indicators of bearing capacity improvement rate, component reinforcement percentage, and reinforcement frequency are [0.3, 0.1, 0.1] respectively, and the weights of the three efficiency indicators of reinforcement duration, construction difficulty coefficient, and ratio of reinforcement cost to extended years are [0.1, 0.2, 0.2].

[0129] According to the statistical parameters of the above safety indicators and efficiency indicators, assuming that all parameters obey the normal distribution, the simulated sampling method is used to analyze the safety indicators, efficiency indicators and comprehensive indicators.

[0130] Based on the mean and variance of each parameter of the selected adaptability analysis index, 5000 samples are randomly selected from the normal distribution by simulated sampling. The safety index, efficiency index, and overall evaluation (adaptability evaluation value) of the 5000 samples are calculated according to formulas 10, 11, and 12 respectively. The calculation results are as follows: Figures 2 to 4 As shown:

[0131] 3. Adaptability analysis results

[0132] The safety index, efficiency index and overall evaluation results calculated by multiple sampling are statistically analyzed for frequency distribution of various indicators, and the mean of the calculation results is obtained through frequency analysis. This mean is used as the value of the corresponding indicator for evaluating the adaptability analysis of advanced reinforcement.

[0133] According to the above analysis, the frequency distribution diagrams of safety index, efficiency index and comprehensive index are as follows: Figures 5 to 16 As shown. Based on this, the mean of the statistical results is obtained, which is used as the corresponding indicator value of the adaptability analysis of the reinforcement scheme. The calculation results are shown in the following table:

[0134] Table 2 Adaptability analysis results

[0135] Indicator Type Paste steel plate Composite fiber bonding Increase cross section External prestressing reinforcement Safety indicators 0.42 0.35 0.48 0.50 Effectiveness Index 0.32 0.23 0.40 0.50 Comprehensive indicators 0.40 0.31 0.48 0.55

[0136] Note: The value of the comprehensive index is the adaptability evaluation value.

[0137] Through the above analysis, the comparison results of safety index, benefit index and comprehensive index among the four advanced reinforcement methods (reinforcement schemes) of bonding steel plate, bonding composite fiber, increasing cross section and external prestressing reinforcement are as follows ( Fig.17 ), the adaptability index value of the external prestressed reinforcement scheme is the largest, indicating that the external prestressed reinforcement scheme has good adaptability to this type of bridge structure and is an advanced reinforcement scheme with good safety and efficiency. The recommended ranking of the adaptability of the advanced reinforcement scheme is: external prestressed reinforcement scheme, increased cross-section reinforcement scheme, steel plate bonding reinforcement scheme, and composite fiber bonding reinforcement scheme. The above conclusions can be used as the basis for the adaptability and post-evaluation of the advanced reinforcement scheme.

[0138] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. The adaptability and reliability analysis method of bridge reinforcement scheme is characterized by: The following steps are involved: Step 1: According to the type of bridge to be reinforced, select multiple primary indicators for evaluating the reinforcement scheme and multiple quantifiable secondary indicators reflecting each primary indicator; Step 2: Subjectively assign weights to each first-level indicator, and the sum of the weights of all first-level indicators is 1; Step 3: The value and weight of each secondary indicator are calculated based on historical test data. The specific method is as follows: select multiple groups of historical test data with the same bridge type as the bridge to be reinforced, calculate the value of the secondary indicator based on each group of historical test data, and calculate the mean and variance of multiple groups of the same secondary indicator, and calculate the weight of each secondary indicator under the same primary indicator based on the mean of the secondary indicator; Then, the mean and variance of each secondary indicator are set to conform to the normal distribution, multiple samples are randomly selected from the normal distribution, and the mean of the secondary indicators of the multiple samples is calculated as the value of the secondary indicator at that time; Step 4: Calculate the adaptability evaluation value of each reinforcement scheme. The specific method is as follows: calculate the weighted sum of multiple secondary indicators under the same primary indicator based on the value and weight of the secondary indicator to obtain the value of the primary indicator, and then calculate the weighted sum of multiple primary indicators based on the value and weight of the primary indicator to obtain the adaptability evaluation value; Step 5: Compare and select the reinforcement scheme with the largest adaptability evaluation value; Among them, the first-level indicators include: safety indicators and efficiency indicators; Safety indicators include: load capacity improvement rate P u , Component reinforcement percentage P s , reinforcement frequency F s ,in, Load capacity increase rate P u : ; in, is the bearing capacity before reinforcement, is the bearing capacity after reinforcement; Component reinforcement percentage P s : ; in, is the total number of components, is the number of unreinforced components; Reinforcement frequency F s : ; in, is the time interval between two reinforcements; Efficiency indicators include: reinforcement duration T s , Construction difficulty coefficient L s , Ratio of reinforcement cost to extended service life ρ m ; Among them, the reinforcement duration refers to the total time required from the beginning to the completion of the bridge reinforcement using the reinforcement scheme; The construction difficulty coefficient is 1 for the most difficult reinforcement scheme, and the construction difficulty coefficients of other reinforcement schemes are between 0 and 1; Ratio of reinforcement cost to extended service life ρ m : ; Among them, M i To strengthen the cost of investment, For the normal service life after reinforcement, The normal service life when no reinforcement measures are taken; The weights of the secondary indicators are calculated using the entropy method.

2. The adaptability and reliability analysis method of the bridge reinforcement scheme according to claim 1 is characterized in that: The specific method for assigning the construction difficulty coefficient is: list all the available reinforcement schemes and arrange them in order of construction difficulty from difficult to easy. The construction difficulty coefficient of the most difficult scheme is 1, and the construction difficulty coefficient of the least difficult scheme is 0. The construction difficulty coefficients of other reinforcement schemes are assigned using linear interpolation.

3. The adaptability and reliability analysis method of the bridge reinforcement scheme according to claim 1 is characterized in that: The reinforcement schemes include: steel plate bonding reinforcement scheme, composite fiber bonding reinforcement scheme, cross-section enlargement reinforcement scheme, and external prestressed reinforcement scheme.

4. The adaptability and reliability analysis method of the bridge reinforcement scheme according to claim 1 is characterized in that: The dimensionless method is used to process the mean and variance of the secondary indicators.

5. The adaptability and reliability analysis method of the bridge reinforcement scheme according to claim 1 is characterized in that: Bridge types include: suspension bridge, arch bridge, and continuous beam bridge.

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