Method and system for evaluating the transverse connection status of hollow slabs in bridges

Abstract

The present invention discloses a method and system for evaluating the transverse connection state of bridge hollow slabs, including the following: (1) Under the action of test loads, obtain the displacements of each hollow slab at the same section of the bridge, and record the displacements of the nth and (n + 1)th hollow slabs corresponding to the ith hinge joint as v n and v n+1 ; (2) Calculate the load transverse distribution coefficient of the hollow slab through the displacement, construct the change rate of the load transverse distribution coefficient of the hinge joint, and use the change rate of the load transverse distribution coefficient as the safety evaluation index of the hinge joint; (3) Compare the safety evaluation index of the hinge joint to be evaluated with the preset safety threshold. When the safety evaluation index of the hinge joint to be evaluated exceeds the safety threshold, issue a risk warning for the current hinge joint. The present invention judges the health status of the hinge joint at the connection of the hollow slab by establishing an evaluation index for evaluating the health status of the hinge joint, realizes the timely evaluation of the hinge joint, and provides a basis for the operation and maintenance of the bridge hinge joint.

Description

Technical Field

[0001] The invention relates to the field of bridge structure safety assessment, and in particular to a method and system for assessing the transverse connection state of a bridge hollow slab. Technical Background

[0002] For hollow slab bridge structures, the safety and durability of hinged joints play an important role in the transmission of lateral forces of the structure. First, hinged joints can allow the structure to deform under stress and temperature changes without affecting the stability of the overall structure, which can reduce stress concentration inside the structure and contribute to the deformation and displacement of the structure; secondly, hinged joints connect the components in the structure, play a role in supporting and stabilizing the structure, so that the various parts of the structure can work together; finally, hinged joints can deform adaptively under conditions such as structural stress changes or material aging, maintaining the stability and integrity of the structure. Therefore, the health status assessment of hinged joints is of great significance. By regularly assessing the health status of hinged joints, problems can be discovered early and measures can be taken to extend the service life of the structure and reduce maintenance costs; through the health status assessment of hinged joints, scientific decisions can be made based on actual data, and the maintenance and repair plan of the structure can be determined to improve the reliability and stability of the structure.

[0003] Traditional hinged joint evaluation methods include the following categories: visual inspection, physical parameter measurement, structural test and structural health monitoring index evaluation. Among them, visual inspection is to manually visually inspect the appearance of the hinged joint to observe whether there are cracks, deformation, corrosion, etc., and preliminarily evaluate the health of the hinged joint; physical parameter measurement uses tools to measure the physical parameters of the hinged joint, such as the collection and analysis of strain, displacement and other data, to obtain the deformation information of the hinged joint, and then evaluate its status; structural tests use static load tests or dynamic tests to test and analyze the overall performance of the structure and the bearing capacity and deformation characteristics of the hinged joint to evaluate the status and health of the hinged joint; structural health monitoring evaluation methods are to use sensor networks and monitoring systems to monitor the vibration, temperature, deformation and other data of the structure in real time, and evaluate the health of the hinged joint by analyzing these data. The above methods have certain defects: they require experienced technicians; they take a lot of time and manpower; they need to purchase the latest testing equipment, and the economic cost is too high.

[0004] In view of the need for health monitoring of a large number of national and provincial highway bridges, if the above-mentioned bridge hinge joint assessment method is adopted, a large amount of economic costs will be incurred. In order to control costs and accurately and quickly obtain assessment information on the performance status of hinge joints, it is urgent to propose a fast and convenient assessment method. Summary of the invention

[0005] Purpose of the invention: In view of the defects of the prior art, the present invention proposes a method for evaluating the lateral connection status of a hollow slab of a bridge, which can obtain the displacement data of the hollow slab of the bridge through a static load test or by extracting the dynamic maximum displacement, and then evaluate the health status of the hinged joint of the hollow slab of the bridge, providing a basis for the maintenance behavior of the hinged joint.

[0006] Technical solution: A method for evaluating the lateral connection status of a hollow slab of a bridge, comprising the following steps:

[0007] (1) Under the test load, the displacements of the hollow slabs of the same section of the bridge are obtained. The displacements of the nth and n+1th hollow slabs corresponding to the i-th hinge joint are v and n and v n+1 , where 1≤i≤N, 1≤n≤N+1, N+1 represents the number of hollow slabs;

[0008] (2) The load lateral distribution coefficient of the hollow slab is calculated by displacement, and the load lateral distribution coefficient change rate of the hinged joint is constructed. The load lateral distribution coefficient change rate is used as the safety evaluation index of the hinged joint;

[0009] (3) Compare the hinged joint safety evaluation index of the hinged joint to be evaluated with the preset safety threshold. When the hinged joint safety evaluation index of the hinged joint to be evaluated exceeds the safety threshold, issue a risk warning for the current hinged joint.

[0010] In one embodiment, step (1) uses a displacement sensor to obtain the displacement of each hollow slab in the same cross section of the bridge, and the displacement sensor is arranged horizontally below the hollow slab, and each displacement sensor is located in the same cross section of the bridge. Preferably, the displacement sensor is arranged in the middle of the main beam span or a quarter of the span.

[0011] In one embodiment, in step (2), a vehicle with a mass of M is used as a test load to obtain the measured static load deflection of N+1 hollow slabs of the same cross section, and the measured static load deflections of the two hollow slabs corresponding to the i-th hinged joint are v n and v n+1 .

[0012] In one embodiment, step (2) monitors the dynamic displacement of N+1 hollow slabs of the same section of the bridge under uninterrupted traffic conditions, and calculates the lateral distribution coefficient of the load of the corresponding hollow slab based on the maximum displacement obtained by monitoring.

[0013] Specifically, the step (2) includes the following contents:

[0014] (2.1) Define the lateral distribution coefficient of the load of the hollow slab:

[0015]

[0016] Among them, mn represents the load lateral distribution coefficient of the nth hollow slab under the test load; v n represents the displacement of the nth hollow slab under the test load;

[0017] (2.2) The change rate of the load lateral distribution coefficient of the hinged joint to be evaluated is calculated based on the load lateral distribution coefficient of the adjacent hollow slab:

[0018]

[0019] Among them, γ i represents the change rate of the load lateral distribution coefficient of the i-th hinged joint; d n,n+1 Indicates the center distance between the nth hollow slab and the n+1th hollow slab;

[0020] The change rate of the load lateral distribution coefficient is used as the safety evaluation index of the hinged joint.

[0021] In one embodiment, step (3) calculates the safety threshold in the following manner:

[0022] The safety evaluation index of hinged joints measured under the k-group safety state is determined, and the safety threshold of the i-th hinged joint is defined as:

[0023] γ i,阈 =μ i +3σ i

[0024] Among them, μ i is the mean value of the change rate of the load lateral distribution coefficient of the i-th hinge joint measured under the k-group historical safety state, σ i is the standard deviation of the change rate of the load lateral distribution coefficient of the i-th hinged joint measured under the k-group safety state;

[0025] When the change rate of the lateral distribution coefficient of the load to be evaluated is greater than the safety threshold, there is a safety hazard in the hinged joint.

[0026] A system for executing the bridge hollow slab transverse connection state assessment method, comprising:

[0027] The displacement acquisition and processing unit is used to obtain the displacement of each hollow slab of the same section of the bridge. The displacements of the nth and n+1th hollow slabs corresponding to the i-th hinge joint are v n and v n+1 ;

[0028] A hinged joint safety evaluation index calculation unit is used to calculate the load transverse distribution coefficient of the hollow slab, and the change rate of the load transverse distribution coefficient is used as the hinged joint safety evaluation index of the hinged joint to be evaluated;

[0029] The state evaluation unit is used to compare the hinged joint safety evaluation index of the hinged joint to be evaluated with a preset safety threshold, and when the hinged joint safety evaluation index of the hinged joint to be evaluated exceeds the safety threshold, a risk warning is issued for the current hinged joint.

[0030] Compared with the prior art, the present invention has the following significant improvements:

[0031] 1. The present invention can obtain the displacement of static adjacent hinged joints through static load tests, construct a hinged joint health status assessment system based on displacement, and regularly complete the assessment of the health status of hinged joints; in addition, the present invention is not limited to obtaining the displacement of hollow slabs through the above static load tests, and can also obtain the dynamic displacement of the bridge at the moment of large deflection through a displacement sensor to replace the static load displacement. This displacement acquisition method is more convenient and quick, does not require traffic interruption, can save a lot of time and economic costs, and reduce the social impact caused by load tests.

[0032] 2. The present invention uses the load distribution coefficient change rate as an evaluation index for the hinged joint state. Under ideal conditions, the closer the hinged joint state evaluation index is to 0, the safer the hinged joint state is. When the index is larger, it indicates that the hinged joint may be abnormal. As the service time of the bridge increases, the historical data accumulated in the bridge monitoring process increases. The present invention constructs a safety threshold value for each hinged joint through historical safety data. When the measured hinged joint state evaluation index exceeds the threshold value, manual intervention is required to repair the damage. After the repair, a new threshold value can be obtained again. Therefore, the safety threshold value will change dynamically, which can timely reflect the risk anomalies of each hinged joint and changes in the service state of the bridge.

[0033] 3. The present invention can make use of the established health monitoring system and utilize mature sensor networks and monitoring systems to obtain historical data or dynamic data without the need to rearrange test sensors, thereby achieving a more comprehensive and rapid hinge joint assessment and providing advice to maintenance units. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of the method for evaluating the transverse connection state of a hollow slab of a bridge according to the present invention;

[0035] Figure 2 A diagram showing the measuring point positions of a photoelectric deflectometer according to an embodiment of the present invention;

[0036] Figure 3 This is an example diagram of deflection data according to an embodiment of the present invention;

[0037] Figure 4 Displacement diagram of each measuring point under actual measurement state in one embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0039] In the first aspect, the present invention adopts static displacement or dynamic displacement to characterize and describe the deformation degree of the bridge, and proposes a method for evaluating the lateral connection state of the hollow slab of the bridge, such as Figure 1 As shown, the method comprises the following steps:

[0040] (1) Under the test load, obtain the displacement of adjacent hollow slabs in the same section of the bridge;

[0041] Preferably, a displacement sensor is used to obtain the displacement of each hollow slab in the same cross section of the bridge. The displacement sensor is arranged transversely below the hollow slab and can be installed at any span position, preferably at the mid-span or a quarter-span position. It should be noted that each displacement sensor is located at the same cross section of the bridge.

[0042] Specifically, suppose a bridge is composed of N+1 hollow slabs, and the N+1 hollow slabs constitute N transverse hinged joints. Assume that the state of the i-th hinged joint needs to be evaluated, and the two adjacent hollow slabs corresponding to the i-th hinged joint are the n-th and n+1-th hollow slabs, respectively, 1≤i≤N, 1≤n≤N+1;

[0043] The vehicle with a mass of M can be used as the load for the static load test to obtain the static load deflection of N+1 hollow slabs with the same cross section. The measured static load deflections of the two hollow slabs corresponding to the i-th hinge joint are v n and v n+1 ; In addition, the dynamic displacement obtained by the health monitoring system can also replace the static displacement of the hollow slab of the static load bridge: record the maximum displacement collected by the displacement sensor under a hollow slab and the corresponding time t, record the displacement of other hollow slabs at time t (also the maximum displacement), so as to determine the dynamic maximum displacement of N+1 hollow slabs with the same section, and calculate the lateral distribution coefficient of the load of each hollow slab based on the maximum displacement; this method does not need to pay attention to the position of the vehicle, nor does it need to interrupt traffic. Compared with the static load test, the measurement efficiency is faster.

[0044] (2) The load lateral distribution coefficient of adjacent hollow slabs is calculated by static displacement or maximum displacement, and the load lateral distribution coefficient change rate of the hinged joint is constructed. The load lateral distribution coefficient change rate is used as the hinged joint safety evaluation index. The specific process is as follows:

[0045] (2.1) Define the lateral load distribution coefficient of the hollow slab:

[0046]

[0047] Among them, m n represents the load lateral distribution coefficient of the nth hollow slab under the test load; vn represents the measured static load deflection of the nth hollow slab under the test load;

[0048] (2.2) The change rate of the load lateral distribution coefficient of the hinged joint to be evaluated is calculated based on the load lateral distribution coefficient of the adjacent hollow slab:

[0049]

[0050] Among them, γ i represents the change rate of the load lateral distribution coefficient of the i-th hinged joint; d n,n+1 Represents the center distance between the nth hollow slab and the n+1th hollow slab.

[0051] (3) Compare the hinged joint safety evaluation index of the hinged joint to be evaluated with the preset safety threshold. The safety threshold is calculated as follows:

[0052] The safety evaluation index of hinged joints measured under the k-group safety state is determined, and the safety threshold of the i-th hinged joint is defined as:

[0053] γ i,阈 =μ i +3σ i

[0054] Among them, μ i is the mean value of the change rate of the load lateral distribution coefficient of the i-th hinge joint measured under the k-group historical safety state, σ i is the standard deviation of the change rate of the load lateral distribution coefficient of the i-th hinged joint measured under the k-group safety state;

[0055] When the load lateral distribution coefficient change rate γ i >γ i,阈 When the risk of the current hinge joint is detected, a risk warning is issued.

[0056] In a second aspect, the present invention provides an evaluation system for executing the above-mentioned bridge hollow slab lateral connection state evaluation method, comprising:

[0057] The displacement acquisition and processing unit is used to obtain the displacement of each hollow slab of the same section of the bridge. The displacements of the nth and n+1th hollow slabs corresponding to the i-th hinge joint are v n and v n+1 , where 1≤i≤N, 1≤n≤N+1, N+1 represents the number of hollow slabs;

[0058] A hinged joint safety evaluation index calculation unit is used to calculate the load transverse distribution coefficient of the hollow slab, and the change rate of the load transverse distribution coefficient is used as the hinged joint safety evaluation index of the hinged joint to be evaluated;

[0059] The state evaluation unit is used to compare the hinged joint safety evaluation index of the hinged joint to be evaluated with a preset safety threshold, and when the hinged joint safety evaluation index of the hinged joint to be evaluated exceeds the safety threshold, a risk warning is issued for the current hinged joint.

[0060] The following is an evaluation of the transverse connection status of the hollow slab of a medium-sized bridge in Jiangsu Province to verify the feasibility and beneficial effects of the present invention.

[0061] 1. Bridge overview and data sources

[0062] The middle bridge is located on G235 National Road in Suqian City, with the center pile number K90+707. The total length of the bridge is 26.0m, and the span combination is 1×20m. The bridge is divided into left and right spans in the transverse direction, and the bridge width combination is 0.5m (anti-collision guardrail) + 3.25m (non-motorized vehicle lane) + 8m (driving lane) + 0.5m (anti-collision guardrail) + 1.1m (isolation belt) + 0.5m (anti-collision guardrail) + 8m (driving lane) + 3.25m (non-motorized vehicle lane) + 0.5m (anti-collision guardrail). Superstructure: prestressed concrete hollow slab beam, plate rubber bearing.

[0063] The structure of the bridge is prestressed concrete hollow slab beam, which belongs to the multi-beam structural system bridge. In order to understand the deflection of the bridge beam under the action of traffic load and monitor the working condition of the lateral connection between the hollow slabs, a photoelectric deflection meter was installed on the left span 0# abutment. Considering the large traffic volume of heavy vehicles on the left lane of the left span, a photoelectric target was installed at the bottom of the 5th to 8th hollow slabs on the left side of the left span 1# span, and a target reference point was installed on the front wall of the left span 1# abutment. A total of 1 photoelectric deflection meter and 5 photoelectric targets (including 1 target reference point) were arranged on the entire bridge. The measuring point information is shown in Table 1, and the layout diagram of the multi-beam deflection measuring points is shown in Table 1. Figure 2 The sampling frequency of the photoelectric deflectometer is 25HZ, and the data collection examples of each sensor are as follows: Figure 3 The hollow slabs of this bridge are not fully covered, so the hinged joints between the four hollow slabs where the photoelectric deflectometers are arranged are numbered, and the positions of the hinged joints are shown in Table 2.

[0064] Table 1 Measurement point information table

[0065]

[0066] Table 2 Hinge position information

[0067]

[0068] 2. Example verification

[0069] (1) Displacement of hollow slab v n to obtain.

[0070] The displacement v of the hollow slab of the bridge is obtained by the displacement sensorn In this example, the number of hinge joints to be tested is 3. Figure 4 The displacement data of each measuring point are shown;

[0071] (2) Construction of hinged joint safety evaluation indicators.

[0072] The maximum displacement of the dynamic monitoring process is selected to calculate the load lateral distribution coefficient corresponding to the hollow slab at the maximum displacement. The load lateral distribution coefficient change rate of the hinged joint is calculated based on the load lateral distribution coefficient, which is used as the hinged joint safety evaluation index to judge the different damage states of the hinged joint. The measured results of the load lateral distribution coefficient of the hollow slab are calculated according to the formula in step (2.1), as shown in Table 3.

[0073] Table 3 Measured table of load lateral distribution coefficient

[0074]

[0075] The measured results of the load lateral distribution variation coefficient calculated according to the formula in step (2.2) are shown in Table 4.

[0076] Table 4 Results of load lateral distribution variation coefficient

[0077]

[0078] (3) Determination of safety threshold and assessment of safety status of hinged joints.

[0079] Determine the evaluation index of the measured hinged joint under the k-group safety state, and define the safety threshold of the i-th hinged joint as:

[0080] γ i,阈 =μ i +3σ i

[0081] Among them, μ i is the mean value of the change rate of the load lateral distribution coefficient of the i-th hinge joint measured under the k-group historical safety state, σ i is the standard deviation of the change rate of the load lateral distribution coefficient of the i-th hinged joint measured under the k-group safety state;

[0082] The change rate of the lateral distribution coefficient is used as the hinged joint evaluation index, and the change rate of the lateral distribution coefficient of the hinged joint to be evaluated is i and γ i,阈 Make a comparison to determine whether the hinge joint poses a safety hazard.

[0083] In this example, based on multiple monitoring data of the three hinged joints under the historical safety state, multiple groups of load lateral distribution coefficient change rates γ of each hinged joint under the safety state are obtained, that is, the hinged joint safety evaluation index under the historical state, as shown in Table 5.

[0084] Table 5 Results of multiple groups of hinged joint safety evaluation indicators under historical conditions

[0085]

[0086]

[0087] Select some data to obtain the mean and standard deviation of the safety evaluation index of the three hinged joints under the historical state. Table 6 shows the safety threshold results obtained based on some data in Table 5. According to the threshold, γ i Both are less than γ i,阈 , the measured results are within the normal range, so the hinged joint is working normally.

[0088] Table 6 Safety threshold results

[0089]

[0090] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable technicians familiar with the technical field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. For ordinary technicians in the technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention.

Claims

1. A method for evaluating the transverse connection state of a bridge hollow slab, characterized in that: The steps include: (1) Under the test load, the displacements of the hollow slabs of the same section of the bridge are obtained. The displacements of the nth and n+1th hollow slabs corresponding to the i-th hinge joint are v and n and v n+1 , where 1≤i≤N, 1≤n≤N+1, N+1 represents the number of hollow slabs; (2) The load lateral distribution coefficient of the hollow slab is calculated by displacement, and the load lateral distribution coefficient change rate of the hinged joint is constructed. The load lateral distribution coefficient change rate is used as the hinged joint safety evaluation index; the specific contents include the following: (2.1) Define the lateral distribution coefficient of the load of the hollow slab: Among them, m n represents the load lateral distribution coefficient of the nth hollow slab under the test load; v n represents the displacement of the nth hollow slab under the test load; (2.2) The change rate of the load lateral distribution coefficient of the hinged joint to be evaluated is calculated based on the load lateral distribution coefficient of the adjacent hollow slab: Among them, γ i represents the change rate of the load lateral distribution coefficient of the i-th hinged joint; d n,n+1 Indicates the center distance between the nth hollow slab and the n+1th hollow slab; The change rate of load lateral distribution coefficient is used as the safety evaluation index of hinged joints; (3) comparing the hinged joint safety evaluation index of the hinged joint to be evaluated with a preset safety threshold, and when the hinged joint safety evaluation index of the hinged joint to be evaluated exceeds the safety threshold, issuing a risk warning for the current hinged joint; The safety threshold is calculated as follows: The safety evaluation index of hinged joints measured under the k-group safety state is determined, and the safety threshold of the i-th hinged joint is defined as: c i,阈 =μ i +3s i Among them, μ i is the mean value of the change rate of the load lateral distribution coefficient of the i-th hinge joint measured under the k-group historical safety state, σ i is the standard deviation of the change rate of the load lateral distribution coefficient of the i-th hinged joint measured under the k-group safety state; When the change rate of the lateral distribution coefficient of the load to be evaluated is greater than the safety threshold, there is a safety hazard in the hinged joint.

2. The method for evaluating the lateral connection state of a hollow bridge slab according to claim 1, characterized in that: In step (1), a displacement sensor is used to obtain the displacement of each hollow slab in the same cross section of the bridge. The displacement sensor is arranged horizontally below the hollow slab, and each displacement sensor is located in the same cross section of the bridge.

3. The method for evaluating the transverse connection state of a hollow bridge slab according to claim 1, characterized in that: In step (2), a vehicle with a mass of M is used as the test load to obtain the measured static load deflection of N+1 hollow slabs with the same cross section. The measured static load deflections of the two hollow slabs corresponding to the i-th hinge joint are v n and v n+1 .

4. The method for evaluating the transverse connection state of a hollow bridge slab according to claim 1, characterized in that: In step (2), the dynamic displacement of N+1 hollow slabs of the same cross section of the bridge is monitored under uninterrupted traffic conditions, and the lateral distribution coefficient of the load of the corresponding hollow slab is calculated based on the maximum displacement obtained by monitoring.

5. The method for evaluating the lateral connection state of a hollow bridge slab according to claim 2, characterized in that: The displacement sensor is arranged at the middle span or one quarter span position of the main beam.

6. A system for executing the method for evaluating the transverse connection state of a hollow slab of a bridge according to any one of claims 1 to 5, comprising: The displacement acquisition and processing unit is used to obtain the displacement of each hollow slab of the same section of the bridge. The displacements of the nth and n+1th hollow slabs corresponding to the i-th hinge joint are v n and v n+1 ; A hinged joint safety evaluation index calculation unit is used to calculate the load transverse distribution coefficient of the hollow slab, and the change rate of the load transverse distribution coefficient is used as the hinged joint safety evaluation index of the hinged joint to be evaluated; The state evaluation unit is used to compare the hinged joint safety evaluation index of the hinged joint to be evaluated with a preset safety threshold, and when the hinged joint safety evaluation index of the hinged joint to be evaluated exceeds the safety threshold, a risk warning is issued for the current hinged joint.

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