Method and system for evaluating transverse connection state of bridge hollow slab

Abstract

A method and system for evaluating a transverse connection state of a bridge hollow slab. The method comprises: (1) under the action of a test load, acquiring displacements of hollow slabs at a same cross section of a bridge, and recording the displacements of an n-th hollow slab and an (n+1)-th hollow slab corresponding to an i-th hinge joint as vn and vn+1, respectively; (2) calculating load transverse distribution coefficients of the hollow slabs on the basis of the displacements, constructing a load transverse distribution coefficient change rate of a hinge joint, and using the load transverse distribution coefficient change rate as a hinge joint safety evaluation indicator; and (3) comparing a hinge joint safety evaluation indicator of a hinge joint to be evaluated with a preset safety threshold, and if the hinge joint safety evaluation indicator of the hinge joint to be evaluated exceeds the safety threshold, issuing a risk early warning for the current hinge joint. By establishing an evaluation indicator for evaluating the health state of a hinge joint, the health state of the hinge joint at the connection position of hollow slabs is determined, thereby evaluating the hinge joint in real time and providing a basis for the operation and maintenance of the hinge joint of a bridge.

Description

Bridge hollow slab transverse connection state evaluation method and system TECHNICAL FIELD

[0001] The present application relates to the field of bridge structure safety evaluation, in particular to a bridge hollow slab transverse connection state evaluation method and evaluation system. TECHNICAL BACKGROUND

[0002] For hollow slab bridge structure, the safety and durability of hinge joint play an important role in the transmission of transverse force of the structure. First, the hinge joint can allow the structure to deform under stress and temperature changes without affecting the stability of the overall structure, can reduce the stress concentration in the structure, and is helpful to the deformation and displacement of the structure; second, the hinge joint connects the components in the structure, plays a supporting and stabilizing role for the structure, so that the parts of the structure can work cooperatively; finally, the hinge joint can adaptively deform under the conditions of stress change or material aging of the structure, maintain the stability and integrity of the structure. Therefore, the health state evaluation of the hinge joint is of great significance. Through regular health state evaluation of the hinge joint, problems can be found early and measures can be taken to prolong the service life of the structure and reduce maintenance cost; through health state evaluation of the hinge joint, scientific decisions can be made according to actual data to determine the maintenance and repair scheme of the structure and improve the reliability and stability of the structure.

[0003] Traditional hinge joint evaluation methods include the following types: visual inspection, physical parameter measurement, structure test and structure health monitoring index evaluation. Among them, visual inspection is to visually inspect the appearance of the hinge joint by artificial visual inspection to observe whether there are cracks, deformation, corrosion and other conditions to preliminarily evaluate the health condition of the hinge joint; physical parameter measurement adopts tools to measure the physical parameters of the hinge joint, such as strain, displacement and other data collection and analysis to obtain the deformation information of the hinge joint and then evaluate its state; structure test adopts static load test or dynamic test to test and analyze the overall performance of the structure and the bearing capacity and deformation characteristics of the hinge joint to evaluate the state and health degree of the hinge joint; structure health monitoring evaluation method is to use sensor network and monitoring system to monitor the vibration, temperature, deformation and other data of the structure in real time, and evaluate the health state of the hinge joint by analyzing these data. The above methods have certain defects: experienced technical personnel are needed; a lot of time and manpower are spent; the latest detection equipment needs to be purchased, and the economic cost is too high, etc.

[0004] In view of the demand for health monitoring of national and provincial highway bridges with large quantity and large size, if the above bridge hinge joint evaluation methods are used, a large amount of economic cost will be generated. In order to control the cost and accurately and quickly obtain the evaluation information of the performance state of the hinge joint, a rapid and convenient evaluation method is urgently needed.

[0005] SUMMARY

[0006] The application aims at providing a bridge hollow slab transverse connection state evaluation method, which can obtain bridge hollow slab displacement data through static load test or by extracting dynamic maximum displacement, and further evaluate the health state of bridge hollow slab hinge joints, thereby providing a basis for hinge joint maintenance.

[0007] The technical scheme is as follows:

[0008] (1) Under the action of test load, the displacement of each hollow slab in the same section of the bridge is obtained, and the displacement of the nth and (n+1)th hollow slab corresponding to the ith hinge joint is respectively v n and v n+1 , wherein 1≤i≤N, 1≤n≤N+1, and N+1 represents the number of hollow slabs;

[0009] (2) The load transverse distribution coefficient of the hollow slab is calculated through the displacement, the load transverse distribution coefficient change rate of the hinge joint is constructed, and the load transverse distribution coefficient change rate is taken as the hinge joint safety evaluation index;

[0010] (3) The hinge joint safety evaluation index of the hinge joint to be evaluated is compared with the preset safety threshold, and when the hinge joint safety evaluation index of the hinge joint to be evaluated exceeds the safety threshold, a risk warning is given to the current hinge joint.

[0011] In one embodiment, step (1) uses displacement sensors to obtain the displacement of each hollow slab in the same section of the bridge, and the displacement sensors are arranged transversely below the hollow slabs, and each displacement sensor is located in the same section of the bridge. Preferably, the displacement sensors are arranged at the midspan or quarter-span position of the main girder.

[0012] In one embodiment, step (2) uses a vehicle with a mass of M as the test load to obtain the measured static deflection of the N+1 hollow slabs in the same section, and the measured static deflection of the two hollow slabs corresponding to the ith hinge joint is respectively v n and v n+1 .

[0013] In one embodiment, step (2) monitors the dynamic displacement of the N+1 hollow slabs in the same section of the bridge under uninterrupted traffic, and calculates the load transverse distribution coefficient of the corresponding hollow slab according to the maximum displacement obtained by monitoring.

[0014] Specifically, step (2) specifically includes the following contents:

[0015] (2.1) Define the load transverse distribution coefficient of the hollow slab:

[0016] Wherein, m ndenotes the load transverse distribution coefficient of the n th hollow slab under the test load; v n denotes the displacement of the n th hollow slab under the test load;

[0017] (2.2) Calculate the load transverse distribution coefficient change rate of the to-be-evaluated hinge joint according to the load transverse distribution coefficient of the adjacent hollow slab:

[0018] wherein, γ i denotes the load transverse distribution coefficient change rate of the i th hinge joint; d n,n+1 denotes the center distance between the n th hollow slab and the n+1 th hollow slab;

[0019] Take the load transverse distribution coefficient change rate as the hinge joint safety evaluation index.

[0020] In one of the embodiments, step (3) calculates the safety threshold value by the following way:

[0021] Determine the measured hinge joint safety evaluation index under k groups of safety states, and define the safety threshold value of the i th hinge joint as:

[0022] γ i,阈 = μ i + 3σ i

[0023] wherein, μ i is the average value of the load transverse distribution coefficient change rate of the i th hinge joint measured under k groups of historical safety states, and σ i is the standard deviation of the load transverse distribution coefficient change rate of the i th hinge joint measured under k groups of safety states;

[0024] When the to-be-evaluated load transverse distribution coefficient change rate is greater than the safety threshold value, the hinge joint has a safety risk.

[0025] A system for performing the bridge hollow slab transverse connection state evaluation method, comprising:

[0026] A displacement acquisition and processing unit is configured to acquire the displacement of each hollow slab of the same section of the bridge, and the displacement of the n th and n+1 th hollow slab corresponding to the i th hinge joint is respectively denoted as v n and v n+1 .

[0027] A hinge joint safety evaluation index calculation unit is configured to calculate the load transverse distribution coefficient of the hollow slab, and take the load transverse distribution coefficient change rate as the hinge joint safety evaluation index of the to-be-evaluated hinge joint.

[0028] The state evaluation unit is configured to compare the hinge joint safety evaluation index of the hinge joint to be evaluated with a preset safety threshold value, and when the hinge joint safety evaluation index of the hinge joint to be evaluated exceeds the safety threshold value, a risk warning is given for the current hinge joint.

[0029] Compared with the prior art, the present application has the following significant progress:

[0030] 1. The present application can obtain the displacement of the adjacent hinge joint in static state through static load test, and construct a hinge joint health state evaluation system based on displacement, so as to realize the evaluation of the health state of the hinge joint at regular intervals. In addition, the present application is not limited to obtaining the displacement of the hollow slab through the above static load test, but can also obtain the dynamic displacement of the bridge at large deflection time through the displacement sensor to replace the static load displacement. This displacement obtaining method is more convenient and fast, does not need to interrupt the traffic, can save a lot of time and economic cost, and reduces the social influence caused by load test.

[0031] 2. The present application takes the load distribution coefficient change rate as the hinge joint state evaluation index. In the ideal state, the closer the hinge joint state evaluation index is to 0, the safer the hinge joint state is. When it is larger, it indicates that the hinge joint may be abnormal. With the increase of the service time of the bridge, the historical data accumulated in the bridge monitoring process increases. The present application constructs the safety threshold value of each hinge joint through the historical safety data. When the measured hinge joint state evaluation index exceeds the threshold value, manual intervention is needed for damage repair. After repair, a new threshold value can be obtained again. Therefore, the safety threshold value will change dynamically, which can timely reflect the risk abnormality of each hinge joint and the change of the service state of the bridge.

[0032] 3. The present application can obtain historical data or dynamic data by means of the already built health monitoring system, using mature sensor network and monitoring system, without the need of re-arranging test sensors, so that more comprehensive and rapid hinge joint evaluation can be realized, and opinions can be provided for maintenance units. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 is a flow chart of the bridge hollow slab transverse connection state evaluation method of the present application;

[0034] Fig. 2 is a photoelectric deflection instrument measuring point position diagram of an embodiment of the present application;

[0035] Fig. 3 is a deflection data example diagram of an embodiment of the present application;

[0036] Fig. 4 is a displacement diagram of each measuring point in the measured state in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings.

[0038] In the first aspect, the deformation degree of the bridge is characterized and described by static displacement or dynamic displacement, and a method for evaluating the transverse connection state of the hollow slab of the bridge is provided, as shown in FIG. 1, which comprises the following steps:

[0039] (1) Under the action of the test load, the displacements of the adjacent hollow slabs of the same section of the bridge are obtained;

[0040] Preferably, the displacement sensors are used to obtain the displacements of the hollow slabs of the same section of the bridge, and the displacement sensors are transversely arranged below the hollow slabs. The installation position can be at any span position, preferably at the midspan or quarter-span position. It should be noted that each displacement sensor is located at the same section of the bridge.

[0041] Specifically, it is assumed that a certain bridge is composed of N+1 hollow slabs, and the N+1 hollow slabs form N transverse connection joints. It is assumed that the state of the ith joint needs to be evaluated, and the adjacent two hollow slabs corresponding to the ith joint are the nth and (n+1)th hollow slabs, 1≤i≤N, 1≤n≤N+1.

[0042] A vehicle with a mass of M can be used as the load for static load test to obtain the static deflection of the N+1 hollow slabs of the same section. The measured static deflections of the two hollow slabs corresponding to the ith joint are v n and v n+1 , respectively. In addition, the dynamic displacement obtained by the health monitoring system can also be used to replace the static displacement of the static load hollow slab of the bridge: the maximum displacement collected by the displacement sensor below a certain hollow slab and the corresponding time t are recorded, and the displacements (also the maximum displacements) of other hollow slabs at time t are recorded to determine the dynamic maximum displacement of the N+1 hollow slabs of the same section. Based on the maximum displacement, the load transverse distribution coefficient of each hollow slab is calculated. This method does not need to pay attention to the position of the vehicle and does not need to interrupt the traffic. Compared with the static load test, the measurement efficiency is faster.

[0043] (2) The load transverse distribution coefficient of the adjacent hollow slabs is calculated by the static displacement or the maximum displacement, the change rate of the load transverse distribution coefficient of the joint is constructed, and the change rate of the load transverse distribution coefficient is used as the joint safety evaluation index. The specific process is as follows:

[0044] (2.1) The load transverse distribution coefficient of the hollow slab is defined as follows:

[0045] wherein m n represents the load transverse distribution coefficient of the nth hollow slab under the action of the test load; v n represents the measured static deflection of the nth hollow slab under the action of the test load.

[0046] (2.2) The change rate of the load transverse distribution coefficient of the joint to be evaluated is calculated according to the load transverse distribution coefficients of the adjacent hollow slabs:

[0047] wherein γ i represents the load transverse distribution coefficient variation rate of the i th hinge joint; d n,n+1 represents the center distance between the n th hollow slab and the n+1 th hollow slab.

[0048] (3) comparing the hinge joint safety evaluation index of the hinge joint to be evaluated with a preset safety threshold value, and the safety threshold value is calculated by the following method:

[0049] measuring the measured hinge joint safety evaluation index under k groups of safety states, and defining the safety threshold value of the i th hinge joint as:

[0050] γ i,阈 = μ i + 3σ i

[0051] wherein μ i is the mean value of the load transverse distribution coefficient variation rate of the i th hinge joint measured under k groups of historical safety states, and σ i is the standard deviation of the load transverse distribution coefficient variation rate of the i th hinge joint measured under k groups of safety states;

[0052] when the load transverse distribution coefficient variation rate γ i to be evaluated is greater than γ i,阈 , a risk warning is given to the current hinge joint.

[0053] In a second aspect, the present application provides an evaluation system for performing the bridge hollow slab transverse connection state evaluation method, comprising:

[0054] a displacement acquisition and processing unit for acquiring the displacement of each hollow slab of the same section of the bridge, and the displacement of the n th and n+1 th hollow slab corresponding to the i th hinge joint is respectively v n and v n+1 , wherein 1≤i≤N, 1≤n≤N+1, and N+1 represents the number of hollow slabs;

[0055] a hinge joint safety evaluation index calculation unit for calculating the load transverse distribution coefficient of the hollow slab, and taking the load transverse distribution coefficient variation rate as the hinge joint safety evaluation index of the hinge joint to be evaluated;

[0056] a state evaluation unit for comparing the hinge joint safety evaluation index of the hinge joint to be evaluated with a preset safety threshold value, and giving a risk warning to the current hinge joint when the hinge joint safety evaluation index of the hinge joint to be evaluated exceeds the safety threshold value.

[0057] The following describes the bridge hollow slab transverse connection state evaluation of a certain bridge in Jiangsu Province, which verifies the feasibility and beneficial effects of the present application.

[0058] 1. Bridge profile and data source

[0059] The bridge is located in G235 National Road in Suqian City, and the center stake number is K90+707. The total length of the bridge is 26.0 m, and the span combination is 1x20 m. The transverse bridge is divided into left and right widths, and the bridge width combination is 0.5 m (crash barrier) + 3.25 m (non-motor vehicle lane) + 8 m (driving lane) + 0.5 m (crash barrier) + 1.1 m (separation zone) + 0.5 m (crash barrier) + 8 m (driving lane) + 3.25 m (non-motor vehicle lane) + 0.5 m (crash barrier). The superstructure is a prestressed concrete hollow slab beam, and the plate type rubber support.

[0060] The bridge structure is a prestressed concrete hollow slab beam, which belongs to a multi-piece beam structure system bridge. In order to understand the deflection of the beam under the action of traffic load and monitor the transverse connection working condition between the hollow slabs, one photoelectric deflection instrument is installed on the left 0# abutment. Considering that the heavy vehicle traffic volume on the left lane of the left width is large, one photoelectric target is installed at the bottom of each of the 5th to 8th hollow slabs on the left side of the left 1# span, and one target reference point is installed on the front wall of the left 1# abutment. A total of one photoelectric deflection instrument and five photoelectric targets (including one target reference point) are arranged on the whole bridge. The measurement point information is shown in Table 1, and the multi-piece beam deflection measurement point arrangement diagram is shown in FIG. 2. The sampling frequency of the photoelectric deflection instrument is 25 HZ, and the data acquisition of each sensor is shown in FIG. 3. The hollow slabs of the bridge are not fully arranged, so the hinge joints between the four hollow slabs where the photoelectric deflection instrument is arranged are numbered, and the hinge joint positions are shown in Table 2.

[0061] Table 1 Measurement point information table

[0062] Table 2 Hinge joint position information table

[0063] 2. Example verification

[0064] (1) Bridge hollow slab displacement v n acquisition.

[0065] The displacement v n of the bridge hollow slab is obtained by the displacement sensor. In this example, the number of measured hinge joints is 3, and the displacement data of each measurement point is shown in FIG. 4.

[0066] (2) Construction of hinge joint safety evaluation index.

[0067] The maximum displacement in the dynamic monitoring process is selected, the load transverse distribution coefficient corresponding to the maximum displacement of the hollow slab is calculated, the load transverse distribution coefficient change rate of the hinge joint is calculated according to the load transverse distribution coefficient, which is used as the hinge joint safety evaluation index, and is used to judge the different damage states of the hinge joint; the measured results of the hollow slab load transverse distribution coefficient are calculated according to the formula in step (2.1), which are shown in Table 3.

[0068] Table 3 Measured transverse load distribution coefficient table

[0069] The measured load transverse distribution coefficient change coefficient is calculated according to the formula of step (2.2), as shown in Table 4.

[0070] Table 4 Load transverse distribution change coefficient result table

[0071] (3) Determination of safety threshold and evaluation of hinge joint safety state.

[0072] The measured hinge joint evaluation index under k group safety state is determined, and the safety threshold of the ith hinge joint is defined as:

[0073] γ i,阈 = μ i + 3σ i

[0074] Wherein, μ i is the mean value of the load transverse distribution coefficient change rate of the ith hinge joint measured under k group historical safety state, and σ i is the standard deviation of the load transverse distribution coefficient change rate of the ith hinge joint measured under k group safety state.

[0075] Taking the transverse distribution coefficient change rate as the hinge joint evaluation index, the load transverse distribution coefficient change rate γ i of the hinge joint to be evaluated is compared with γ i,阈 to determine whether the hinge joint has safety hidden danger.

[0076] In this example, according to the monitoring data of three hinges under historical safety state, the load transverse distribution coefficient change rate γ of each hinge under safety state is obtained, that is, the hinge safety evaluation index under historical state, as shown in Table 5.

[0077] Table 5 Historical state multiple hinge safety evaluation index result table

[0078] Select some data to calculate the mean value and standard deviation of the hinge safety evaluation index of the three hinges under historical state. The safety threshold result obtained according to part of the data in Table 5 is shown in Table 6. According to the threshold value, γ i is less than γ i,阈 , and the measured result is within the normal range, so the hinge working state is normal.

[0079] Table 6 Safety threshold result table

[0080] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable the skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. For ordinary skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method for evaluating the transverse connection state of a bridge hollow slab, characterized by, The method comprises the following steps: (1) Under the action of test load, the displacement of each hollow slab of the same section of the bridge is obtained, and the displacement of the nth and nth+1 hollow slabs corresponding to the ith hinge joint is respectively v n and v n+1 , wherein 1≤i≤N, 1≤n≤N+1, and N+1 represents the number of hollow slabs; (2) calculating the load transverse distribution coefficient of the hollow slab by displacement, and constructing the load transverse distribution coefficient variation rate of the hinge joint, wherein the load transverse distribution coefficient variation rate is used as the hinge joint safety evaluation index; (3) comparing the hinge joint safety evaluation index of the hinge joint to be evaluated with the preset safety threshold value, and performing risk warning on the current hinge joint when the hinge joint safety evaluation index of the hinge joint to be evaluated exceeds the safety threshold value.

2. The method for evaluating the transverse connection state of a bridge hollow slab according to claim 1, wherein In step (1), the displacement sensors are used to obtain the displacement of each hollow slab at the same section of the bridge, and the displacement sensors are arranged transversely below the hollow slab, and each displacement sensor is located at the same section of the bridge.

3. The method for evaluating the transverse connection state of a bridge hollow slab according to claim 1, wherein In step (2), the vehicle with mass M is used as the test load to obtain the measured static deflection of the N+1 hollow slabs of the same section, and the measured static deflection of the two hollow slabs corresponding to the ith hinge joint is respectively denoted as vi n and vi+1 n+1 .

4. The method for evaluating the transverse connection state of a bridge hollow slab according to claim 1, wherein In step (2), the dynamic displacement of N+1 hollow slabs at the same section of the bridge is monitored under the condition of uninterrupted traffic, and the load transverse distribution coefficient of the corresponding hollow slab is calculated according to the maximum displacement obtained by monitoring.

5. The method for evaluating the transverse connection state of a bridge hollow slab according to claim 1, wherein The step (2) specifically comprises the following contents: (2.1) Defining the load transverse distribution factor of a hollow core slab: wherein m n represents the load transverse distribution coefficient of the nth hollow core slab under the test load; v n represents the displacement of the nth hollow core slab under the test load; (2.2) The load transverse distribution coefficient change rate of the hinge joint to be evaluated is calculated according to the load transverse distribution coefficient of the adjacent hollow core slab: wherein γ i represents the load transverse distribution coefficient variation rate of the ith joint; d n,n+1 represents the center distance between the nth hollow slab and the n+1th hollow slab; The load transverse distribution coefficient variation rate is used as the hinge joint safety evaluation index.

6. The method for evaluating the transverse connection state of a bridge hollow slab according to claim 1, wherein In step (3), the safety threshold value is calculated by the following method: The measured hinge joint safety evaluation index under k groups of safety states is determined, and the safety threshold value of the ith hinge joint is defined as: gamma i,阈 = mu i + 3 sigma i wherein μ i is the mean of the measured load lateral distribution factor variation rate of the i-th joint in the k-group of historical safety states, σ i is the standard deviation of the measured load lateral distribution factor variation rate of the i-th joint in the k-group of safety states. When the load transverse distribution coefficient variation rate to be evaluated is greater than the safety threshold value, the hinge joint has a safety hazard.

7. The method for evaluating the transverse connection state of a bridge hollow slab according to claim 1, wherein The displacement sensors are arranged at the midspan or quarter-span position of the main girder.

8. A system for performing the bridge hollow slab transverse connection state evaluation method according to any one of claims 1-7, comprising: A displacement acquisition and processing unit is configured to acquire the displacement of each hollow slab of the same section of the bridge, and the displacement of the nth and (n+1)th hollow slabs corresponding to the ith hinge joint is respectively denoted as v n and v n+1 ; a hinge joint safety evaluation index calculation unit for calculating the load transverse distribution coefficient of the hollow slab, and using the load transverse distribution coefficient variation rate as the hinge joint safety evaluation index of the hinge joint to be evaluated; a state evaluation unit for comparing the hinge joint safety evaluation index of the hinge joint to be evaluated with the preset safety threshold value, and performing risk warning on the current hinge joint when the hinge joint safety evaluation index of the hinge joint to be evaluated exceeds the safety threshold value.

Images