CN107341282B - Improved bridge deterioration evaluation method based on previous year technical state - Google Patents

Abstract

The invention discloses an improved natural deterioration evaluation method based on the technical state of the bridge in the previous year, and adopts four parameters: the technical state score when the bridge is completed, the time when the technical state of the bridge is not degraded, the statistical service life of the bridges of the same type, and the operating time of the bridge. , a bridge technical state deterioration process model is established that can describe the bridge technical state deterioration after the bridge is completed and enters the operation period, while considering the changes of environment, load and material properties. Using the bridge technical state deterioration model of the present invention to evaluate and predict the bridge technical state, the bridge can be detected, maintained, repaired and strengthened in a targeted manner, so as to ensure the rationality of the scale of repair, reinforcement and transformation, and to keep the bridge in good technical quality. status, which is of great significance to bridge structural safety, sustainable operation and socio-economic development.

Description

An improved bridge deterioration assessment method based on the technical status of the previous year

technical field

The invention belongs to the field of bridge detection, evaluation and maintenance, and in particular relates to an improved bridge deterioration evaluation method based on the technical state of the previous year.

Background technique

Bridges all go through the process of construction, service, functional degradation and scrapping. During use, with the passage of time, under the action of internal or external, or natural unfavorable factors, material aging and structural damage will occur. The accumulation of such damage will lead to deterioration of structural performance and reliability. In the case of reinforcement, its function will inevitably decline at an accelerated rate. Because bridges are composed of basic materials such as steel and concrete, after statistical analysis, the deterioration of new and in-service bridges has similar laws, so it is very important to study and predict the reliability and status of bridges in the future. In order to better predict the service state and remaining life of bridges, many scholars at home and abroad have studied the reliability degradation model of bridge structures, but the data and literature on the technical state degradation model of bridge structures are still relatively few.

For example, the paper "Research on the Deterioration Model of Concrete Bridges" published in the journal "Chinese and Foreign Highways" has established a two-segment, three-segment linear deterioration model, and an n-segment linear and nonlinear deterioration model based on the effective function for concrete bridge structures. The value of the parameters is given by the standard analysis and the basic two-stage nonlinear model expression without maintenance is shown in formula (1).

β(t)=β. -α(tt _I )F(t _I ) (1)

In formula (1): β. is the reliability of the bridge structure at the beginning of its construction; _tI is the time when the bridge structure begins to deteriorate, in years; α is the structural reliability deterioration rate of the bridge structure without maintenance. The degradation model of the bridge makes maintenance decision-making more concise and convenient.

For example, the paper "Research on the Optimization of Steel Bridge Maintenance Strategy Based on Performance Deterioration Analysis" published in the journal "World Bridge" comprehensively considers the influencing factors such as environment and load, and uses reliability indicators and state indicators to represent the technical status of bridges, and introduces an improved Logistic The dynamic particle swarm optimization algorithm and Monte-Carlo simulation are used to propose the primary and secondary nonlinear degradation models of the reliability index and state index during the service process of the bridge, and the calculation model of the time-varying reliability index of the bridge structure is established. Formula (2):

In formula (2): β. is the reliability of the bridge structure at the beginning of its construction, t _I is the time when the bridge structure begins to deteriorate, in years; E _I is the environmental impact coefficient, _SE is the equivalent damage coefficient; α ₁ is the development according to the structural stress state and traffic volume Condition-determined reliability index damage accumulation factor.

For example, the paper "Research on Probabilistic Maintenance Model of Deteriorated Bridges and Cost Optimization of Maintenance Programs" published in the journal "Journal of Railway Science and Engineering" established the following nonlinear models of bridge technical state indicators:

In formula (3): C. is the initial state index of the bridge structure; _tCI is the time when the bridge state index begins to deteriorate, in years; α ₂ is the deterioration rate of the bridge structure.

The above model can be used not only for newly built bridges, but also for old bridges that have been in service for many years. However, the estimation of the deterioration model has a large deviation from the actual value, which makes the assessment work less accurate and credible. In order to accurately evaluate and predict the technical status of bridges, the bridges can be inspected, maintained, repaired and reinforced in a targeted manner, so that human and material resources can be targeted, ensure the rationality of the scale of maintenance, reinforcement and transformation, and keep the bridge in good condition. It has important practical and practical significance for bridge safety life, sustainable operation and social and economic development. Therefore, in order to solve the above problems, an assessment method of bridge technical state deterioration is urgently needed, so as to record, describe and predict the bridge technical state deterioration law.

SUMMARY OF THE INVENTION

In order to improve the evaluation and prediction accuracy of bridge technical state, the improved natural deterioration evaluation method based on the bridge technical state of the previous year of the present invention adopts an exponentially changing nonlinear function expression as the bridge technical state deterioration model to describe the bridge technical state. The deterioration law of the state; the present invention is realized by the following technical solutions:

An improved natural deterioration evaluation method based on the technical state of the bridge in the previous year, the evaluation method is based on the technical state score of the bridge in the previous year, the time when the technical state of the bridge is not degraded, the statistical service life of the bridge of the same type, and the operating time of the bridge Based on the data obtained, the bridge condition deterioration assessment is carried out, and the assessment method includes the following steps:

Step a. Obtain the initial technical state score D _c when the bridge is built, the time N _c when the bridge technical state is not degraded, the service time n of the bridge, and the bridge technical state scores D(1), D(2), D(3)...D(n);

Step b. Calculate the deterioration rate α of the bridge technical state;

Step c. Calculate the value of the power A in the deterioration model according to the calculation of the deterioration rate α and the statistical service life N _d of the same type of bridge;

Step d. Determine the degradation model of the bridge according to the parameters obtained in steps a to c, draw a technical state degradation curve, and complete the degradation assessment; the degradation model is as follows:

Among them: D _c is the initial technical state score of the bridge when it is built, N _d is the statistical service life of the same type of bridge, n is the service time, A is the power, and D(n-1) is the technical state score of the bridge in the previous year.

When the use time of the bridge is n years after completion, according to the bridge technical status scores D(1), D(2), D(3)...D(n) in the past years, if the evaluation time in the past years is continuous, then according to the formula (5) Calculate the beam technical state deterioration rate α; if the evaluation time is not continuous over the years, then calculate the beam technical state deterioration rate α according to formula (6):

α=max{D(1)-D(2),D(2)-D(3),...,D(n-1)-D(n)} (5)

Among them: D(1) is the technical status score of the bridge when the service time is the first year, D(2) is the technical state score of the bridge when the service time is the second year, and D(3) is the use time of the bridge. The technical status score in the third year, D(j) is the use time of the bridge is the technical state score of the bridge in the jth year, D(k) is the use time of the bridge is the technical state score of the bridge in the kth year, D(n-1 ) is the technical state score of the bridge in the (n-1)th year, and D(n) is the technical state score of the bridge when the service time is the nth year.

The statistical service life N _d of the bridges of the same type is determined as follows: the statistical service life N _{d of small concrete bridges is 40 years; the statistical service life N d of concrete medium bridges is 55 years; the statistical service life N d of concrete} bridges is the value 80 years; the statistical service life N _d of the concrete bridge is 100 years.

When _Nc is not considered in the bridge technical state deterioration model based on the previous year or the last assessment, A is related to the maximum attenuation rate α of bridge technical state deterioration.

Table 1. Relationship between bridge technical state deterioration rate α, power A, and statistical service life N _d

The power A is related to the maximum attenuation rate α of bridge technical state deterioration, and a certain power exponent A can also be selected according to the following method to calculate the technical state deterioration attenuation rate α.

When the statistical service life N _d of the bridges of the same type is 40 years, the relationship between A and α is determined according to the following formula, and the value of A is determined according to the following formula:

α=-0.0098A ⁵ +0.1958A ⁴ -1.57A ³ +6.4224A ² -13.141A+17.16 (7)

When the statistical service life N _d of the bridges of the same type is 55 years, the relationship between A and α is determined according to the following formula, and the value of A is determined according to the following formula:

α=-0.0044A ⁵ +0.101A ⁴ -0.9274A ³ +4.3025A ² -0.9473A+13.95 (8)

When the statistical service life N _d of the bridges of the same type is 80 years, the relationship between A and α is determined according to the following formula, and the value of A is determined according to the following formula:

α=-0.0051A ⁵ +0.112A ⁴ -0.9745A ³ +4.2864A ² -9.4767A+12.28 (9)

When the statistical service life N _d of the bridges of the same type is 100 years, the relationship between A and α is determined according to the following formula, and the value of A is determined according to the following formula:

α=-0.0038A ⁵ +0.0849A ⁴ -0.7621A ³ +3.4664A ² -7.9519A+10.602 (10)

Among them: α is the deterioration rate of the bridge technical state, A is the power of the deterioration model.

Step e. Calculate the predicted value of the bridge technical state evaluation according to the bridge deterioration model, evaluate the current life interval of the bridge, predict the bridge maintenance time node according to the bridge technical state maintenance critical point, and detect it in the corresponding life interval and time node of the bridge. Maintenance, repair and reinforcement.

Advantages of the present invention:

Based on the statistical analysis and research of a large number of bridge technical state data, and through parameter sensitivity analysis, the bridge technical state evaluation and prediction parameters are scientifically selected. Bridge technical status: According to the bridge technical status evaluation value, the bridge can be detected, maintained, repaired and reinforced in a targeted manner, so as to keep the bridge in a good technical state and effectively prolong the service life of the bridge.

Description of drawings

FIG. 1 is a schematic diagram of a bridge technical state deterioration curve in the deterioration assessment method according to the present invention.

Detailed ways

Long-term tracking of the technical status of a concrete continuous girder bridge, the bridge is 75m long, the upper structure is a 3×25m cast-in-situ continuous box girder, the girder height is 1.5m, and the width is 11.20m; the bridge abutment is a gravity abutment, bridge piers It is a column-type pier, and the pier and platform foundations are all enlarged foundations; the bridge deck in the bridge deck system is a cement concrete surface layer, the guardrail is made of steel pipe guardrails, and the bridge deck is provided with scuppers; the bridge was completed in 1988 and opened to traffic in 2009. The age of the bridge is 22 years; according to the visual inspection results at the time of delivery and acceptance, the initial technical condition score Dc of the bridge is determined to be 95 points; during the 22 years, the bridge has been tested and evaluated 4 times, and 1988 is the initial bridge construction time , the inspection and evaluation time were in 1997, 2001, 2005 and 2009 respectively, and the technical status score results were D(1)=Dc=95, D(10)=90, D(14)=85, D(18)= 76, D(22)=55, the evaluation time and evaluation results are shown in Table 2.

Table 2 Evaluation time and technical status evaluation results

Substituting the technical state score result into Equation (6) can obtain the maximum bridge technical state deterioration rate α=5.1 during 22 years. Since the bridge deck is a concrete bridge, the statistical service life N _d is 55 years, according to Equation (8) The power A in the parameters of the deterioration model is calculated to be 3.0; the initial technical state score Dc, the service life N _d , and the power A are substituted into formula (4), and the following deterioration model expression can be obtained:

The deterioration evaluation curve of the model expression is drawn, as shown in Figure 1. From this figure, we can see the relationship between the bridge's technical state and service life. When the bridge's service time is 25 years (ie, 2012), the predicted value of the technical state evaluation reaches 50 , need to be reinforced; when the service time is 29 years (ie 2016), the predicted value of the technical state assessment reaches 30, and it needs to be overhauled.

Claims (8)

1. An improved natural deterioration assessment method based on the technical status of the bridge in the previous year, the assessment method is based on the technical status score of the bridge in the previous year, the time when the technical status of the bridge is not degraded, the statistical service life of the same type of bridges and the operating time of the bridge The bridge state deterioration assessment is carried out on the basis of the data obtained, and it is characterized in that: the assessment method includes the following steps: Step a. Obtain the initial technical state score D _c when the bridge is built, the time N _c when the bridge technical state is not degraded, the service time n of the bridge, and the bridge technical state scores D(1), D(2), D(3)...D(n); Step b. Calculate the deterioration rate α of the bridge technical state; Step c. Calculate the value of the power A in the deterioration model according to the calculation of the deterioration rate α and the statistical service life N _d of the same type of bridge; Step d. Determine the degradation model of the bridge according to the parameters obtained in steps a to c, draw a technical state degradation curve, and complete the degradation assessment; the degradation model is as follows: Among them: D _c is the initial technical state score of the bridge when it is built, N _d is the statistical service life of the same type of bridge, n is the service time, A is the power, and D(n-1) is the technical state score of the bridge in the previous year; Step e. Calculate the predicted value of the bridge technical state assessment according to the bridge deterioration model, evaluate the current life interval of the bridge, predict the bridge maintenance time node according to the bridge technical state maintenance critical point, and maintain the bridge in the corresponding life interval and time node of the bridge. Repair and reinforcement. 2. the improved natural deterioration assessment method based on the technical state of the bridge in the previous year according to claim 1, it is characterized in that: when the bridge service time is n years, obtain the bridge technical state score in n years, when the assessment time is continuous in n years , the bridge technical state deterioration rate α is determined as follows: α=max{D(1)-D(2),D(2)-D(3),...,D(n-1)-D(n)} Among them: D(1) is the technical status score of the bridge when it has been used for 1 year, D(2) is the technical status score of the bridge when it has been used for 2 years, D(3) is the technical status score of the bridge when it has been used for 3 years, and D (n-1) is the technical state score of the bridge when the service time of the bridge is the (n-1) year, and D(n) is the technical state score of the bridge when the service time is the nth year. 3. the improved natural deterioration assessment method based on the bridge technical state of the previous year according to claim 1, it is characterized in that: when the use time is n years, obtain the bridge technical state score within n years, when the assessment time is discontinuous within n years , the bridge technical state deterioration rate α is determined as follows: Among them: D(1) is the technical status score of the bridge when the service time is the first year, D(2) is the technical state score of the bridge when the service time is the second year, and D(3) is the use time of the bridge. The technical status score in the 3rd year, D(j) is the use time of the bridge is the technical state score of the bridge in the jth year, D(k) is the use time of the bridge is the technical state score of the bridge in the kth year, D(n-1 ) is the technical state score of the bridge in the (n-1)th year, and D(n) is the technical state score of the bridge when the service time is the nth year. 4. The improved natural deterioration assessment method based on the technical state of bridges in the previous year according to claim 1, characterized in that: the statistical service life N _d of the bridges of the same type is determined as follows; the statistical service life N d of small concrete bridges The value of _d is 40 years; the statistical service life of concrete medium bridges is 55 years _; the statistical service life of concrete bridges is 80 years _; the statistical service life of concrete bridges is 100 years _. 5. The improved natural deterioration assessment method based on the technical state of bridges in the previous year according to claim 4, wherein: when the statistical service life N _d of the same type of bridges is 40 years, the value of A is as follows: The formula is determined, and the value of A is determined according to the following formula: α=-0.0098A ⁵ +0.1958A ⁴ -1.57A ³ +6.4224A ² -13.141A+17.16 Among them: α is the deterioration rate of the bridge technical state, A is the power of the deterioration model. 6. The improved natural deterioration assessment method based on the technical state of bridges in the previous year according to claim 1 or 3, characterized in that: when the statistical service life N _d of the bridges of the same type is 55 years, the value of A is Determine according to the following formula, and determine the value of A according to the following formula: α=-0.0044A ⁵ +0.101A ⁴ -0.9274A ³ +4.3025A ² -0.9473A+13.95 Among them: α is the deterioration rate of the bridge technical state, A is the power of the deterioration model. 7. The improved natural deterioration assessment method based on the technical state of bridges in the previous year according to claim 4, characterized in that: when the statistical service life N _d of the same type of bridges is 80 years, the value of A is as follows: The formula is determined, and the value of A is determined according to the following formula: α=-0.0051A ⁵ +0.112A ⁴ -0.9745A ³ +4.2864A ² -9.4767A+12.28 Among them: α is the deterioration rate of the bridge technical state, A is the power of the deterioration model. 8. The improved natural deterioration assessment method based on the technical state of bridges in the previous year according to claim 4, characterized in that: when the statistical service life N _d of the bridges of the same type takes a value of 100 years, the value of A is as follows: The formula is determined, and the value of A is determined according to the following formula: α=-0.0038A ⁵ +0.0849A ⁴ -0.7621A ³ +3.4664A ² -7.9519A+10.602 Among them: α is the deterioration rate of the bridge technical state, A is the power of the deterioration model.

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