Real-time dynamic safety assessment method for in-service small and medium span bridge

Abstract

A real-time dynamic safety assessment method for in-service small and medium span bridges comprises the following steps: step a, building a health monitoring system, and collecting analysis data in real time; b, simulation analysis and collected data processing; step c, evaluation parameter calculation: according to a result obtained by data processing, evaluation parameters including a deflection overload coefficient mu and a deflection recovery coefficient # imgabs0 # are respectively calculated; step d, when each evaluation parameter of an analysis result meets the conditions that mu is less than or equal to 0.2 and # imgabs1 #, the bridge is overloaded, but the degree that the actual deflection of the bridge exceeds a calculated value is relatively small, the structure can bear the overload to a certain degree, and meanwhile, the structure can bear the deflection of the bridge to a certain degree. After overload, the bridge can recover deformation well, the elastic performance of the structure is good, internal damage is small, and the structure is in a relatively safe state. The method can effectively solve the problem of safety real-time effective evaluation of in-service small and medium-span bridges, and can effectively solve the realistic problem of whether the bridges can continue to pass or not after being overloaded in real time.

Description

Technical Field

[0001] The invention relates to the field of bridge detection, evaluation and reinforcement, and in particular to a method for real-time dynamic safety evaluation of in-service small and medium-span bridges. Background Art

[0002] By the end of 2023, in my country's highway bridge operation system, small and medium span bridges account for 82.6%. They are widely distributed in urban and rural areas and have become an indispensable key node in the regional transportation network. With the booming e-commerce economy, the logistics operation load continues to increase, and the transportation links are always in a high-intensity busy state. In real scenarios, vehicle overloading is difficult to eliminate, which has brought a heavy burden to the operation of small and medium span bridges. How to achieve real-time and effective assessment of bridge structure safety under current operating conditions is a problem worth solving.

[0003] In response to the problem of real-time and effective safety assessment of small and medium-span bridge structures, the engineering community proposed to use bridge health monitoring technology to carry out real-time monitoring. This technology can timely collect measured data such as strain and displacement, use numerical simulation comparison method to compare measured and designed calculated values, determine whether each measured value exceeds the limit, and carry out early warning disposal of the exceeded data. However, although health monitoring technology can carry out real-time over-limit early warning disposal, it has shortcomings in building a scientific and systematic safety assessment system. The existing health monitoring safety assessment system focuses on the simple limitation of the degree of over-warning, and only judges the current structural risk based on the over-limit data. For small and medium-span bridges, this is one-sided. It should be noted that overloading of bridges in service occurs from time to time. If based on the existing safety assessment system, a large number of bridges will no longer be suitable for continued load-bearing. However, this is inconsistent with reality.

[0004] In view of the large number of small and medium-span bridges and the high incidence of overloading, it is of great significance to develop a comprehensive assessment method for the real-time dynamic safety of in-service small and medium-span bridges. It not only takes into account the overload effect, but also accurately tracks the dynamic recovery process of the bridge state after overloading, so as to comprehensively, timely and effectively assess the real safety status of the bridge and fill the gap in the existing health monitoring and assessment system. Summary of the invention

[0005] In order to overcome the shortcomings of the existing technology and solve the problem of real-time and effective evaluation of the safety of small and medium-span bridge structures, the evaluation of the dynamic recovery performance of bridges after overloading is added to the original health monitoring and evaluation system to achieve the purpose of real-time and effective evaluation of bridge safety. The present invention provides a method for real-time dynamic safety evaluation of in-service small and medium-span bridges, introduces dimensionless parameters μ (deflection overload coefficient) and φ (deflection recovery coefficient), and the comprehensive use of the above parameters can effectively achieve the purpose of evaluating the real-time safety of small and medium-span bridges.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A method for real-time dynamic safety assessment of in-service small and medium span bridges comprises the following steps:

[0008] Step a: Build a health monitoring system and collect analysis data in real time. For the analysis structure (small and medium span bridges), design the health monitoring system framework, build the hardware system on site, develop the background software platform, conduct joint debugging of software and hardware, collect the on-site structural response data in real time, and generate the response data time history curve.

[0009] Step b, simulation analysis and data collection processing. Based on the short-term effect detection algorithm of the normal use limit state, simulation analysis is performed to calculate the maximum deflection of the beam and slab; based on the real-time data collected on site, the overload section data is intercepted and converted to obtain the maximum measured deflection of the beam and slab under the overload and the deflection of the bridge after overload recovery.

[0010] Step c, calculation of evaluation parameters: Based on the results obtained from data processing, the evaluation parameters are calculated respectively: deflection overload coefficient μ and deflection recovery coefficient The deflection overload coefficient μ is used to assess the extent to which the actual deflection of the bridge exceeds the design calculated deflection. The larger the coefficient, the more serious the deflection caused by the overload exceeds the design expectation. It is used to assess the ability of a bridge structure to recover to its original state after an overload (a heavy vehicle passing through the bridge). The larger the coefficient, the better the bridge's ability to recover after an overload, and the better its elastic properties.

[0011] Step d: Real-time dynamic safety assessment of small and medium span bridges, and draw conclusions. The analysis results show that each assessment parameter meets the following requirements: μ≤0.2 and When the load is too high, the bridge is overloaded, but the actual deflection of the bridge exceeds the calculated value to a small extent. The structure can withstand this overload to a certain extent. At the same time, the bridge can recover its deformation well after the overload. The elastic performance of the structure is good, the internal damage is small, and the structure is in a relatively safe state.

[0012] Furthermore, the deflection overload coefficient μ reflects the influence of overload on the deflection of the bridge. Assuming that the deflection calculated under the design load is δ c , the maximum deflection caused by an overloaded vehicle crossing the bridge is δ a . Calculate the deflection overload coefficient μ according to the following formula (1).

[0013] The deflection recovery coefficient Reflects the ability of the bridge structure to recover to its original state after overloading. Assuming that the maximum deflection of the bridge during overloading is δ max , the deflection of the bridge after overloading is δ recovery , the deflection that has not recovered after overload is δ rThe deflection recovery coefficient is calculated according to the following formula (2):

[0014]

[0015] Furthermore, the deflection overload coefficient μ and the deflection recovery coefficient When μ≤0.2, the structure is relatively safe; when 0.2<μ≤0.5, the structure has potential safety hazards. Comprehensively analyze the structure; when μ>0.5, the structure has a great safety hazard, combined with the deflection recovery coefficient Decide whether to organize professionals to conduct a comprehensive inspection and assessment of the bridge. When the structure is strong, the elasticity is good and the safety is high; When the structure is damaged to a certain extent, further inspection is required to see if there are any potential cracks or material performance degradation; When the bridge structure is seriously damaged, its safety is seriously threatened and a detailed inspection and assessment of the bridge is required.

[0016] In order to solve the problem of real-time and effective safety assessment of in-service small and medium-span bridge structures, this method is based on the health monitoring system of small and medium-span bridges and innovatively proposes a method combining the deflection overload coefficient μ and the deflection recovery coefficient A comprehensive real-time evaluation method.

[0017] The beneficial effects of the present invention are mainly manifested in:

[0018] (1) Using the assessment parameters—μ (deflection overload coefficient) and φ (deflection recovery coefficient) combined with the health monitoring system, it is possible to effectively and in real time overcome the practical problem of whether the bridge can continue to be used after being overloaded;

[0019] (2) The use of assessment parameters—μ (deflection overload coefficient) and φ (deflection recovery coefficient) can effectively solve the problem of real-time and effective safety assessment of in-service small and medium-span bridges;

[0020] (3) The real-time evaluation of the dynamic recovery performance of bridges after overloading is a useful supplement to the existing real-time dynamic safety evaluation of small and medium-span bridge health monitoring. The evaluation system not only solves the problem of real-time warning of overload of small and medium-span bridges, but also effectively solves the problem of real-time dynamic comprehensive safety evaluation of small and medium-span bridges.

[0021] (4) Based on the comprehensive evaluation results, it is possible to effectively avoid judging the current structural risks based solely on overload data, which would result in a large number of bridges being assessed as unsuitable for continued load-bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a mind map for designing health monitoring systems for small and medium span bridges;

[0023] Figure 2 This is a schematic elevation diagram of the measurement point layout of the real bridge health monitoring system;

[0024] Figure 3 This is a cross-sectional schematic diagram of the measurement point arrangement of a real bridge health monitoring system, in which 1 temperature and humidity sensor and 5 deflection sensors are set.

[0025] Figure 4 This is another cross-sectional schematic diagram of the measurement point arrangement of a real bridge health monitoring system, in which 1 temperature and humidity sensor and 12 deflection sensors are set. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Reference Figure 1 to Figure 4 , a method for real-time dynamic safety assessment of in-service small and medium span bridges, comprising the following steps:

[0028] Step a: Build a health monitoring system and collect analysis data in real time. Figure 2 )), design a health monitoring system framework (such as Figure 1 ), build the hardware system on site, develop the background software platform, conduct joint debugging and testing of software and hardware, realize real-time collection of on-site structural response data, and generate response data time history curve.

[0029] Step b, simulation analysis and data collection processing. Based on the short-term effect detection algorithm of the normal use limit state, simulation analysis is performed to calculate the maximum deflection of the beam and slab; based on the real-time data collected on site, the overload section data is intercepted and converted to obtain the maximum measured deflection of the beam and slab under the overload and the deflection of the bridge after overload recovery.

[0030] Step c: Calculation of evaluation parameters. Based on the results of data processing, the evaluation parameters are calculated: deflection overload coefficient μ and deflection recovery coefficient. The deflection overload coefficient μ is used to assess the extent to which the actual deflection of the bridge exceeds the design calculated deflection. The larger the coefficient, the more serious the deflection caused by the overload exceeds the design expectation. It is used to assess the ability of a bridge structure to recover to its original state after an overload (a heavy vehicle passing through the bridge). The larger the coefficient, the better the bridge's ability to recover after an overload, and the better its elastic properties.

[0031] The deflection overload coefficient μ reflects the influence of overload on the deflection of the bridge. Assuming that the deflection calculated under the design load is δ c , the maximum deflection caused by an overloaded vehicle crossing the bridge is δ a . Calculate the deflection overload coefficient μ according to the following formula (1).

[0032] The deflection recovery coefficient Reflects the ability of the bridge structure to recover to its original state after overloading. Assuming that the maximum deflection of the bridge during overloading is δ max , the deflection of the bridge after overloading is δ recovery , the deflection that has not recovered after overload is δ r The deflection recovery coefficient is calculated according to the following formula (2):

[0033]

[0034] The deflection overload coefficient μ and the deflection recovery coefficient When μ≤0.2, the structure is relatively safe; when 0.2<μ≤0.5, the structure has potential safety hazards. Comprehensively analyze the structure; when μ>0.5, the structure has a great safety hazard, combined with the deflection recovery coefficient Decide whether to organize professionals to conduct a comprehensive inspection and assessment of the bridge. When the structure is strong, the elasticity is good and the safety is high; When the structure is damaged to a certain extent, further inspection is required to see if there are any potential cracks or material performance degradation; When the bridge structure is seriously damaged, its safety is seriously threatened and a detailed inspection and assessment of the bridge is required.

[0035] Step d: Real-time dynamic safety assessment of small and medium span bridges, and draw conclusions. The analysis results show that each assessment parameter meets the following requirements: μ≤0.2 and When the load is too high, the bridge is overloaded, but the actual deflection of the bridge exceeds the calculated value to a small extent. The structure can withstand this overload to a certain extent. At the same time, the bridge can recover its deformation well after the overload. The elastic performance of the structure is good, the internal damage is small, and the structure is in a relatively safe state.

[0036] In order to solve the problem of real-time and effective safety assessment of in-service small and medium-span bridge structures, this embodiment proposes a health monitoring method for small and medium-span bridges, and innovatively proposes a method combining the deflection overload coefficient μ and the deflection recovery coefficient A comprehensive real-time evaluation method.

[0037] Reference Figure 2 , Figure 3 and Figure 4 ,in Figure 2 In the 9th span, deflection (12) indicates 12 deflection sensors, and temperature and humidity (1) indicates 1 temperature and humidity sensor; in the 11th and 12th spans, deflection (5) indicates 5 deflection sensors; in the 13th span, deflection (12) indicates 12 deflection sensors; Figure 3and Figure 4 1 represents the temperature and humidity sensor, and 2 represents the deflection sensor. Arrange the actual bridge site hardware equipment, develop the background software system, and conduct joint debugging and testing of the software and hardware on site and in the background to form a stable health monitoring system. Based on the real-time data collection of the health monitoring system, combined with the deflection overload coefficient μ and the deflection recovery coefficient Conduct comprehensive real-time assessments of bridges.

[0038] The above description is for the convenience of those skilled in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications and apply the general principles described herein to other examples without creative work. Therefore, the present invention is not limited to the specifics here, and modifications made without departing from the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A method for real-time dynamic safety assessment of in-service small and medium span bridges, characterized in that: The method comprises the following steps: Step a: Build a health monitoring system, collect analysis data in real time, analyze the structure of small and medium span bridges, design the health monitoring system framework, build the hardware system on site, develop the background software platform, conduct joint debugging of software and hardware, realize real-time collection of on-site structural response data, and generate response data time history curves; Step b, simulation analysis and data collection processing: Based on the short-term effect detection algorithm of the normal use limit state, simulation analysis is performed to calculate the maximum deflection of the beam and slab; based on the real-time data collected on site, the overload section data is intercepted to convert the maximum measured deflection of the beam and slab under the overload and the deflection of the bridge after overload recovery; Step c, calculation of evaluation parameters: Based on the results obtained from data processing, the evaluation parameters are calculated respectively: deflection overload coefficient μ and deflection recovery coefficient The deflection overload coefficient μ is used to assess the extent to which the actual deflection of the bridge exceeds the design calculated deflection. The larger the coefficient, the more serious the deflection caused by the overload exceeds the design expectation. It is used to evaluate the ability of a bridge structure to recover to its original state after an overload. The larger the coefficient, the better the bridge's ability to recover after an overload, and the better its elastic performance. Step d: Real-time dynamic safety assessment of small and medium span bridges. The conclusion is: the analysis results show that the evaluation parameters meet the following requirements: μ≤0.2 and When the load is too high, the bridge is overloaded, but the actual deflection of the bridge exceeds the calculated value to a small extent. The structure can withstand this overload to a certain extent. At the same time, the bridge can recover its deformation well after the overload. The elastic performance of the structure is good, the internal damage is small, and the structure is in a relatively safe state.

2. A method for real-time dynamic safety assessment of in-service small and medium span bridges as claimed in claim 1, characterized in that: In step c, the deflection overload coefficient μ reflects the influence of overload on the deflection of the bridge. Assuming that the deflection calculated under the design load is δ c , the maximum deflection caused by an overloaded vehicle crossing the bridge is δ a . Calculate the deflection overload coefficient μ according to the following formula (1); The deflection recovery coefficient Reflects the ability of the bridge structure to recover to its original state after overloading. Assuming that the maximum deflection of the bridge during overloading is δ max , the deflection of the bridge after overloading is δ recovery , the deflection that has not recovered after overload is δ r , calculate the deflection recovery coefficient according to the following formula (2):

3. A method for real-time dynamic safety assessment of in-service small and medium span bridges as claimed in claim 1 or 2, characterized in that: In the step d, the deflection overload coefficient μ and the deflection recovery coefficient When μ≤0.2, the structure is relatively safe; When 0.2<μ≤0.5, the structure has potential safety hazards. Combined with the deflection recovery coefficient Comprehensively evaluate the structure; when μ>0.5, the structure has a great safety hazard, combined with the deflection recovery coefficient Decide whether to organize professionals to conduct a comprehensive inspection and assessment of the bridge; When the structure is strong, the elasticity is good and the safety is high; When the structure is damaged to a certain extent, further inspection is required to see if there are any potential cracks or material performance degradation; When the bridge structure is seriously damaged, its safety is seriously threatened and a detailed inspection and assessment of the bridge is required.

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