CN204228372U - Be applicable to the integrated apparatus that small bridge is fast and safely diagnosed - Google Patents

Abstract

The utility model discloses an integrated device suitable for fast and safe diagnosis of small and medium-sized bridges, which comprises: a mobile detection vehicle, an impact excitation device and a data acquisition device, an extendable cantilever system at the lower end of the mobile detection vehicle site; the impact excitation device It includes a loading bracket and a loading hammer arranged on the loading bracket; the data acquisition device includes a load cell installed on the lower end surface of the loading hammer for measuring the time-history data of the force formed by impacting the bridge road surface and a load cell at the end of the cantilever system for measuring Accelerometer sensor for bridge acceleration response. The utility model ensures the smooth implementation of the mobile impact vibration test for small and medium bridges, and ensures the reliability of the structural performance evaluation results obtained by analyzing the measured impact vibration data, and has higher advantages than the traditional method.

Description

An integrated device suitable for rapid and safe diagnosis of small and medium bridges

technical field

The utility model relates to the field of dynamic testing and safety evaluation of medium and small bridges in civil engineering and traffic engineering. It can carry out rapid impact and vibration tests on bridges to achieve the purpose of carrying capacity evaluation and safety diagnosis of small and medium-sized bridges.

Background technique

There are a huge number of small and medium-sized bridges on my country's national highway network. How to ensure their health and safety and avoid bridge collapse accidents has become an urgent scientific problem. Structural bearing capacity is an important indicator of structural safety. Truck static load test is an on-site test method widely accepted by bridge engineers. It completes the effective evaluation of bridge bearing capacity by statically loading the tested bridge and observing the corresponding bridge deformation and other indicators. The Ministry of Communications of my country's "Methods for Appraisal of Bearing Capacity of Old Highway Bridges" provides detailed regulations and explanations for the static load test method of trucks. The American Handbook of State Assessment of Highway Bridges (AASHTO) also makes a similar statement for the truck static load test. The truck static load test results are reliable, and it is a method specified in the code, so it is widely used in the evaluation of the bearing capacity of small and medium-sized bridges at home and abroad. But its disadvantage is that the test is expensive, time-consuming and labor-intensive, which leads to a long time for the bridge to be closed and open to traffic during the test, which affects traffic, which is the last thing bridge managers want to see.

There are a large number of small and medium-sized bridges in my country, most of which are in disrepair and have potential safety hazards, but they are faced with the embarrassment of very limited funds and manpower for maintenance. Therefore, the costly and inefficient truck static load test described above cannot be widely used for safety assessment. The above-mentioned status quo and the urgency of conducting safety assessments on large and medium-sized bridges in actual projects call for the emergence of new rapid test and evaluation methods and devices to achieve convenient and fast rapid testing and safety surveys on large and medium-sized bridges.

Contents of the invention

Aiming at the major engineering requirements of the health diagnosis of small and medium-sized bridges introduced in the background technology section and the lack of management and maintenance funds, the utility model discloses a rapid test integrated device for small and medium-sized bridges and a safety evaluation system. It is a fast mobile shock and vibration test, and can obtain bridge bearing capacity and safety performance evaluation results similar to the traditional laborious and time-consuming truck static load test method.

The technical solution of the present utility model is as follows:

An integrated device suitable for fast and safe diagnosis of small and medium-sized bridges, comprising: a mobile inspection vehicle, an impact excitation device and a data acquisition device, an extendable cantilever system is provided at the lower end of the mobile inspection vehicle; the impact excitation The device includes a loading bracket and a loading hammer arranged on the loading bracket; the data acquisition device includes a load cell installed on the lower end surface of the loading hammer for measuring the time history data of the force formed by impacting the bridge road surface and located at the An accelerometer sensor at the end of the cantilever system to measure the acceleration response of the bridge.

The cantilever system includes a horizontal drive cylinder and a vertical drive cylinder, and the accelerometer sensor is located on the output end of the horizontal drive cylinder.

The beneficial effects of the technical solution described in the utility model are:

The integrated device in the utility model adopts mobile measurement means to perform mobile and fast impact vibration tests on small and medium bridges. No need to arrange sensors before testing, no need to install acquisition systems, and truly achieve low-cost and high-efficiency small and medium bridges. test. It has strong practicability, convenience, low cost, and high accuracy. Therefore, it is expected to be popularized and applied to small and medium-sized bridges with a large number of small and medium bridges in our country but with limited management and maintenance funds.

Description of drawings

Fig. 1 is the structural representation of the utility model device;

Fig. 2 is the schematic diagram of the concrete implementation of the utility model device on the bridge;

A certain impact force time course diagram observed in the embodiment of Fig. 3;

The response time chart of a certain point acceleration observed in the embodiment of Fig. 4;

The first four-order formation diagram identified in the embodiment of Figure 5, where a is the first order, b is the second order, c is the third order, and d is the fourth order;

Figure 6 is a schematic diagram of the displacement prediction results of a span of a simply supported beam bridge in the embodiment.

Detailed ways

Below in conjunction with Fig. 1, the specific embodiment of the present utility model is described in detail:

The utility model device includes a mobile detection vehicle 1, an integrated controller 2, a data analysis system 3, a sensor arrangement and a measurement system 4, an impact excitation device 5 and an accelerometer 6, and is formed by organically coordinating the functions of each component through the integrated controller. An automated system for rapid testing of small and medium bridges. Its main body is a movable testing vehicle 1 (shown in Figure 1), which can move freely to the bridge deck testing area. The accelerometer, which is connected to the automatic telescopic cantilever system and can move freely in the vertical and horizontal directions and guide the data acquisition device to the bridge deck measurement point, is arranged under the chassis of the inspection vehicle, where the horizontal and vertical movements are driven by the horizontal drive cylinder and the vertical The direct drive cylinder is completed and then pressed against the bridge deck to achieve an effective measurement of the acceleration response of the bridge. The impact excitation device 5 in the detection vehicle can generate impact force to excite the bridge for impact vibration test, and simultaneously record the impact force time course, denoted as u, and the bridge acceleration response time course, denoted as y. In a short period of time after the excitation and measurement are completed, the data analysis system 3, that is, the data processing device, can complete the collation and analysis of the recorded data, and fully automatically obtain the evaluation results of the bearing capacity of the structure.

After obtaining the time course data u, y, first write the time course data in the form of matrix according to the formula (13-15) in step a) to obtain the input matrix U _p , U _f , output matrix Y _{i, i} , Y _p , Y _f , And the input-output combination matrix W _p , After obtaining the input and output matrices, substitute these matrices into formula (16) in b) to calculate the projection budget of the matrix, and obtain matrices O _i , Z _i and Z _i+1 . Select appropriate weight coefficients W ₁ and W ₂ , perform singular value decomposition on O _i according to formula (17) in c) to obtain matrix U ₁ , S ₁ , and then substitute U ₁ , S ₁ , W ₁ into formula (18 in d) ) to get matrices Γ _i and Γ _i-1 . Finally, substituting the previously obtained matrices U _f , Y _{i, i} , Zi _i , Z _i+1 , Γ _i , and Γ _i-1 into equation (19) in e) to obtain state matrices A, C and K, from K B and D are found in , so as to complete the solution process of the state matrix.

According to the process of identifying the bridge flexibility matrix by the data processing device, first, the state matrix A is decomposed according to the eigenvalues of the formula (3), and the frequency and damping of the structure are obtained by using the eigenvalues of the formula (4-5), and then using the formula (6) ) combined with the state matrix C to obtain the modal array of the structure. Then, the acceleration frequency response of the structure is written in the form expressed by the state matrix A, B, C, D, see formula (7). Utilizing the characteristic that the acceleration frequency response function represented by the state matrix can be decoupled, the modal scaling coefficient q _i of the structure is obtained by comparison. The process is firstly the acceleration frequency response function structure, see formula (8); The frequency response function of the structure is compared with the frequency response function of the usual form, see formula (9); from formula (9), the modal scaling coefficient of the structure is solved by using the least square method, see formula (10). Substitute the modal scaling factor q _i , formation φ _i and λ _ci into formula (11) to obtain the flexibility matrix of the structure.

When the flexibility matrix is known, the displacement prediction of the structure under any static load can be performed, and it is only necessary to substitute the vector composed of the load into formula (12) for calculation.

Example

Taking a certain single-span prestressed concrete T-shaped simply supported beam bridge (single-span 14.6m long, 14.6m wide) as an example, the specific implementation of the utility model is described in detail.

1. Divide the structural units, use the mobile inspection vehicle to quickly test the bridge, and obtain the structural acceleration response of the bridge under the impact vibration force.

According to the arm length of the telescopic cantilever and the length of the bridge, several units are reasonably divided. For example, assuming that the total length of the telescopic cantilever is 8m and the single-span span of a simply supported girder bridge is 14.6m, each span can be divided into two units. Use a mobile testing vehicle to conduct impact tests on each unit in turn and record the time history data u={u ₁ , u ₂ ,...,u ₂₀₀₀₀ } of the impact force and the acceleration time history y={y ₁ of each acceleration measuring point , y ₂ , ..., y ₂₀₀₀₀ }, a total of 20000 data points. Figure 3 is the time history of the impact test force at a certain point, and Figure 4 is the time history data of the acceleration response at a certain point.

2. Calculation of state matrix A, B, C, D

Arrange the obtained impact force and acceleration responses in the form of formulas (13), (14), and (15), where i=40. Project the matrix of the combined structure according to formula (16) to obtain matrices O _i , Z _i and Z _i+1 , and perform singular value decomposition of O _i according to formula (17) to obtain matrices Γ _i and Γ _i-1 . Substitute the matrices O _i , Z _i , Z _i+1 , Γ _i and Γ _i-1 into formula (19), solve the least squares solution, obtain the state matrices A, C and K, and then obtain the state from K Matrix B and D.

3. Calculation of damping ratio, formation and modal scaling factor

The frequency and formation of the structure can be obtained by substituting the obtained matrices A and C into equations (3), (4), (5) and (6). The identified frequencies of the first four orders are 7.43, 9.67, 15.55, and 26.82 Hz respectively, and the identified displacement arrays of the first to fourth orders are shown in Figure 5. Using formula (10) to calculate the modal scaling coefficient q _i of the structure, the calculated first four modal scaling coefficients are: -0.510+0.704i, 0.511+0.047i, -0.217+0.036i, 0.090-0.067i, In the formula, i is the imaginary unit.

4. Displacement compliance identification

Substitute the eigenvalue λ _ci , the formation φ _i calculated in step 3 and the modal scaling coefficient q _i into formula (11) to calculate the displacement compliance matrix f, which is a matrix of 18×18.

5. Prediction of displacement response of structures under arbitrary static loads

Select 18 nodes of a single-span simply supported beam bridge to apply force, and the force at each point is the same as 1000KN. Substituting into formula (12) for calculation, the displacement response of the structure under the action of force F is obtained as [0.0470; 0.0512; 0.0533; 0.0534 ; 0.0502; 0.0464; 0.0659; 0.0723; 0.0757; 0.0754; 0.0716; The comparison between the predicted value of the displacement of each node corresponding to the applied force and the real value is shown in Figure 6. It can be seen that the real measured value corresponding to the predicted value is very close, thus verifying the validity and accuracy of the identified flexibility matrix. sex.

Claims (2)

1. An integrated device suitable for fast and safe diagnosis of small and medium-sized bridges, comprising: a mobile inspection vehicle, an impact excitation device and a data acquisition device, and there is an extendable cantilever system at the lower end of the mobile inspection vehicle site; the described The impact excitation device includes a loading bracket and a loading hammer arranged on the loading bracket; the data acquisition device includes a load cell installed on the lower end surface of the loading hammer for measuring the time history data of the force formed by impacting the bridge road surface and Accelerometer sensors at the end of the cantilever system to measure the acceleration response of the bridge. 2. An integrated device suitable for fast and safe diagnosis of small and medium-sized bridges according to claim 1, wherein the cantilever system includes a horizontal drive cylinder and a vertical drive cylinder, and the accelerometer sensor is located at the On the output end of the horizontal drive cylinder.