Bridge Real-time Monitoring and Evaluation System and Its Construction Method

Abstract

The present invention discloses a real-time monitoring and evaluation system for a bridge and its construction method. The system includes a first strain gauge installed in the mid-span bottom plate of a reinforced concrete box girder, second strain gauges respectively installed at the mid-span and the 1 / 4-span of a Bailey beam, a third strain gauge installed at the mid-span of a disc buckle support, a first temperature sensor installed at the mid-span of the Bailey beam, a second temperature sensor installed at the mid-span of the disc buckle support, and an anemometer installed on the disc buckle support. The first strain gauge, the second strain gauges, the third strain gauge, the first temperature sensor, the second temperature sensor, and the anemometer respectively send the collected real-time data to a data processing module through a collection and transmission instrument. The data processing module is used to obtain the finite element design value of the bridge by using finite element simulation analysis, and then compare and evaluate the collected real-time data with the finite element design value of the bridge.

Description

Technical Field

[0001] The present invention relates to a real-time monitoring and evaluation system for bridges and a construction method thereof. Background Art

[0002] With the rapid development of China's economy, bridges, as buildings that span adverse geological conditions such as ravines and mountain streams, and meet various traffic needs to ensure the smooth passage of vehicles and pedestrians, have been widely used in infrastructure construction. Because the bridge construction process is complex and cumbersome, in order to ensure the safety of bridge construction and various diseases generated in the bridge structure during subsequent operation, continuous monitoring and control of the bridge should be maintained.

[0003] Bridge construction monitoring is an important part of the bridge construction process. Its main content is to monitor the stress, deformation, temperature, etc. of the monitoring target, which is the basis for ensuring construction safety and the completed bridge structure meeting the design requirements.

[0004] Traditional bridge construction monitoring systems need to deploy a large number of sensors for data collection, and then send the collected data to professionals for analysis and processing in order to evaluate the current state of the monitored structure, and then formulate corresponding countermeasures. Traditional bridge construction monitoring has high costs and low monitoring efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a real-time monitoring and evaluation system for bridges and a construction method thereof to solve the problems of high cost and low efficiency in existing bridge construction monitoring.

[0006] To solve the above technical problems, the present invention provides a real-time monitoring and evaluation system for bridges, including a first strain gauge installed in the mid-span bottom plate of a reinforced concrete box girder, second strain gauges respectively installed at the mid-span and the 1 / 4 span of a Bailey beam, a third strain gauge installed at the mid-span of a disc buckle support, a first temperature sensor installed at the mid-span of a Bailey beam, a second temperature sensor installed at the mid-span of a disc buckle support, and an anemometer installed on the disc buckle support. The first strain gauge, the second strain gauges, the third strain gauge, the first temperature sensor, the second temperature sensor, and the anemometer respectively send the collected real-time data to a data processing module through a collection and transmission instrument; the data processing module uses a finite element analysis model to obtain relevant parameters of other positions of the bridge based on the collected real-time data, and then compares the collected real-time data and the relevant parameters of other positions of the bridge obtained through analysis with the warning thresholds respectively, and then evaluates the bridge according to the comparison results.

[0007] Further, when the data processing module compares and concludes that the collected real-time data is greater than the threshold value of the finite element design value of the bridge, it issues a warning message to remind the staff to investigate various influencing factors at the construction site, then modifies the finite element analysis model according to the on-site influencing factors, and then uses the modified finite element analysis model to analyze and evaluate the entire bridge based on the real-time data collected subsequently.

[0008] Further, the data processing module is a web application developed based on Python Dash.

[0009] Further, the first strain gauge is a vibrating wire concrete strain gauge embedded in the mid-span bottom slab of the reinforced concrete box girder.

[0010] Further, the second strain gauge is a vibrating wire surface strain gauge. The second strain gauge and the first temperature sensor are fixedly installed on the longitudinal beam of the Bailey truss by adhesive.

[0011] Further, the third strain gauge is a vibrating wire surface strain gauge. The third strain gauge is fixed on the formwork support by welding. The second temperature sensor is fixedly installed on the formwork support by adhesive. The anemometer is fixed on the formwork support by buckle or bundling.

[0012] In addition, the present application also provides a construction method for the above-mentioned real-time monitoring and evaluation system of the bridge, and the method includes:

[0013] Place the distribution box at a location where the reinforced concrete box girder is not easily disturbed by construction; then install the acquisition and transmission instrument in the distribution box;

[0014] Before pouring concrete for the box girder, embed the first strain gauge into the mid-span bottom slab of the reinforced concrete box girder;

[0015] Use sandpaper to polish the surface of the mid-span longitudinal beam of the Bailey truss, and then use adhesive to fixedly install the second strain gauge and the first temperature sensor on the finely polished longitudinal beam of the Bailey truss;

[0016] Fix the third strain gauge on the formwork support by welding, bond the second temperature sensor on the formwork support by adhesive, and fix the anemometer on the formwork support by buckle or rope;

[0017] Connect the extension wires of the first strain gauge, the second strain gauge, the third strain gauge, the first temperature sensor, the second temperature sensor, and the anemometer to the acquisition and transmission instrument respectively; then connect the acquisition and transmission instrument to the data processing module through the wireless communication unit, and use the data processing module to perform real-time analysis and evaluation on the bridge according to the collected real-time data.

[0018] Furthermore, when embedding the first strain gauge, make a figure-eight knot on the cable of the outlet end of the first strain gauge, and then fix the first strain gauge on the steel bars at the mid-span bottom plate position.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) By adopting the remote monitoring technology, it is possible to view parameters such as the stress, temperature, and wind speed of the monitored object at any time and place, which is convenient for using various devices that can log in to the web page (such as smartphones, computers, etc.), improving the real-time performance and universality of data monitoring.

[0021] (2) Combining construction monitoring with finite element simulation analysis to construct the functional relationship between the stresses at various monitoring points of the bridge, so that under the condition of only arranging a limited number of strain gauges, the stress changes at other positions can be inferred, thereby providing guidance for ensuring construction quality.

[0022] (3) The acquisition instrument and various sensors only need to be installed in place once to achieve long-term monitoring. When the sensors are damaged, the modular composition method is also conducive to later maintenance and replacement of accessories.

[0023] (4) By adopting the parameter evaluation function, setting the early warning threshold guided by the existing specifications as the safe domain of the design value, and comparing it with the real-time monitoring data, it can enable the monitoring personnel to always understand the stress state of the bridge, thereby reducing potential hazards and ensuring the safety of bridge construction and subsequent operation. Description of the Drawings

[0024] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The same reference numerals are used to represent the same or similar parts in these drawings. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0025] Figure 1 is the schematic diagram of the bridge real-time monitoring and evaluation system;

[0026] Figure 2 is the cross-sectional schematic diagram of the reinforced concrete box girder;

[0027] Figure 3 is the schematic diagram of the Bailey beam structure;

[0028] Figure 4 is the schematic diagram of the disc buckle support structure;

[0029] Figure 5 is the stress distribution diagram of the Bailey beam analyzed by Ansys.

[0030] Wherein: 1. Reinforced concrete box girder; 2. Wireless acquisition and transmission instrument and distribution box; 3. First strain gauge; 4. Bailey beam; 5. Second strain gauge; 6. First temperature sensor; 7. Scaffolding with button locks; 8. Third strain gauge; 9. Second temperature sensor; 10. Anemometer. Detailed implementation mode

[0031] As Figure 1 A real-time bridge monitoring and evaluation system shown in the figure includes a first strain gauge 3 installed in the mid-span bottom plate of the reinforced concrete box girder 1, second strain gauges 5 respectively installed at the mid-span and the 1 / 4-span of the Bailey beam 4, a third strain gauge 8 installed at the mid-span of the scaffolding with button locks, a first temperature sensor 6 installed at the mid-span of the Bailey beam, a second temperature sensor 9 installed at the mid-span of the scaffolding with button locks, and an anemometer installed on the scaffolding with button locks. The first strain gauge 3, the second strain gauges 5, the third strain gauge 8, the first temperature sensor 6, the second temperature sensor 9, and the anemometer 10 respectively send the collected real-time data to the data processing module through the acquisition and transmission instrument 2; the data processing module uses the finite element analysis model to obtain the relevant parameters of other positions of the bridge according to the collected real-time data, and then compares the collected real-time data and the relevant parameters of other positions of the bridge obtained by the analysis with the warning thresholds respectively, and then evaluates the bridge according to the comparison results.

[0032] The present invention combines construction monitoring with finite element simulation analysis to construct a functional relationship between the stresses of each monitoring point of the bridge, so as to infer the stress changes at other positions under the condition of only arranging a limited number of strain gauges, thereby providing guidance for ensuring construction quality.

[0033] According to an embodiment of the present application, when the data processing module compares and obtains that the collected real-time data is greater than the threshold value of the finite element design value of the bridge, it issues a warning message to remind the staff to investigate various influencing factors at the construction site, and then corrects the finite element analysis model according to the on-site influencing factors, and then uses the corrected finite element analysis model to analyze and evaluate the entire bridge according to the subsequent collected real-time data.

[0034] According to an embodiment of the present application, the acquisition and transmission instrument 2 can adopt a VS208 - 432 wireless acquisition and transmission instrument 2. When installing the acquisition and transmission instrument 2, it should be placed in the distribution box and the power supply should be maintained to ensure continuous data and avoid accidents. In view of the complex construction environment at the construction site, the equipment should be grounded (for example: bury a copper wire in the screw and ground the other end) to avoid interference.

[0035] According to an embodiment of the present application, the data processing module is a web program developed based on Python Dash. The web monitoring program developed using Python enables the stress, temperature, wind speed and other parameters of the monitored object to be viewed at any time and anywhere using various devices that can log in to the web (such as smartphones, computers, etc.), improving the real-time performance and versatility of data monitoring.

[0036] According to an embodiment of the present application, as Figure 2 shown, the first strain gauge 3 is a vibrating wire concrete strain gauge embedded in the mid-span bottom slab of the reinforced concrete box girder 1. The vibrating wire concrete strain gauge adopts a vibrating wire elastic beam structure and is suitable for long-term embedding in beams, columns, pile foundations, supports, retaining walls, hydraulic structures, linings, piers and footings of concrete structures and their bedrocks to monitor their stress and strain.

[0037] According to an embodiment of the present application, as Figure 3 shown, the second strain gauge 5 is a vibrating wire surface strain gauge. The second strain gauge 5 and the first temperature sensor 6 are fixedly installed on the longitudinal beam of the Bailey beam 4 by means of glue. The second strain gauge 5 can be used to collect the strain data at the mid-span and the 1 / 4 span of the Bailey beam 4 in real time. The temperature data on the longitudinal beam of the Bailey beam 4 can be collected in real time through the first temperature sensor 6.

[0038] According to an embodiment of the present application, as Figure 4 shown, the third strain gauge 8 is a vibrating wire surface strain gauge. The third strain gauge 8 is fixed on the formwork support 7 by welding. The second temperature sensor 9 is fixedly installed on the formwork support by means of glue. The anemometer 10 is fixed on the formwork support by means of buckles or bundling. The strain data, temperature data and wind speed data of the formwork support 7 can be collected respectively through the third strain gauge 8, the second temperature sensor 9 and the anemometer 10.

[0039] In addition, the present application also provides a construction method for the above-mentioned bridge real-time monitoring and evaluation system, and the method includes:

[0040] Place the distribution box at a location on the reinforced concrete box girder 1 that is not easily disturbed by construction, and after ensuring that its power supply can be maintained for a long time, place the acquisition and transmission instrument 2 therein to avoid interfering with the work of the acquisition and transmission instrument 2 during the construction process;

[0041] Before pouring the concrete of the box girder, make a figure-eight knot on the cable at the outlet end of the first strain gauge 3 (vibrating wire concrete strain gauge) to avoid subsequent construction from breaking the wiring, and then tie it to the steel bars at the mid-span bottom slab position with steel wires, and prepare an extension wire of appropriate length to the acquisition and transmission instrument 2;

[0042] First, use sandpaper to polish the surface of the longitudinal beam at the mid-span of the 4th span of the Bailey beam, tidy up the measured area to be smooth and clean. Then, use adhesive (such as AB glue) to stick the second strain gauge 5 (vibrating wire surface strain gauge) and the first temperature sensor 6 on the longitudinal beam of the Bailey beam 4, and then extend the extension wire to the acquisition and transmission instrument 2;

[0043] For the formwork support 7 composed of round tubes, welding should be used to ensure that the third strain gauge 8 (vibrating wire surface strain gauge) can be fixed on the formwork support. First, make the fixture contact with the limiting end of the test bar, and the right end of the test bar contact with the outside of the fixture. Tighten the screw, weld the fixtures at both ends of the test bar to the object to be measured. When using welding, the test bar must be used to avoid damaging the instrument. After the fixture cools down, remove the test bar. Then, align the two ends of the third strain gauge 8 with the outside of the fixture and tighten the screw to complete the installation; The second temperature sensor 9 is stuck on the formwork support with adhesive (such as AB glue). The anemometer 10 is horizontally installed at the cross beam of the formwork support 7 by means of buckles or wire bundling. After each sensor is installed in place, extend the extension wires of each sensor to the acquisition and transmission instrument 2;

[0044] After confirming that each sensor is installed in place, wrap the connection of the extension wire with insulating tape, and then connect each strain gauge and temperature sensor to the common end of the SENⅠ port of the acquisition and transmission instrument 2. The first strain gauge 3, the second strain gauge 5, and the third strain gauge 8 are respectively connected to channels ch1 - ch3 of the acquisition and transmission instrument 2. The first temperature sensor 6 and the second temperature sensor 9 are respectively connected to channels ch13 - ch14 of the acquisition and transmission instrument 2. When connecting, the black wire is the common end of the vibrating wire, and the white wire is the common end of the temperature; The anemometer 10 is connected to the SENⅣ port through the extension wire. The model of the anemometer 10 used in the present invention is VMS - 3000 - FS - I20. The orange wire at the anemometer 10 end is the positive pole and is connected to the red wire of the sensor interface of the acquisition and transmission instrument 2; The black wire and the green wire at the anemometer 10 end are respectively the negative pole and GND, and are connected together to the black wire of the sensor interface of the acquisition and transmission instrument 2; The blue wire at the anemometer 10 end is the analog signal OUT and is connected to the orange wire of the sensor interface of the acquisition and transmission instrument 2;

[0045] After completing all sensor connections, connect the acquisition and transmission instrument 2 to the PC through the RS232 line. Open the setting software of the acquisition and transmission instrument 2, set the data sending method of the acquisition and transmission instrument 2 to GPRS TCP, set the scanning time, data storage time, and automatic sending time to 4 minutes. After filling in the TCP server address, restart the acquisition and transmission instrument 2, and then real-time acquisition and transmission data can be sent to the web end through the corresponding address;

[0046] The web - side monitoring program of the present invention is a real - time monitoring and evaluation system developed based on Python, integrating the temperature for real - time data viewing, the dial of the anemometer 10, and the stress curve. In the stress broken - line graph, the finite - element design value is used as the evaluation basis. The white area is the safe area. When the stress curve enters the yellow area, vigilance should be maintained. When the stress reaches the red line of the design value, various influencing factors at the construction site (such as construction load, actual box - girder weight, etc.) should be investigated in detail. Then, the finite - element model should be modified according to the actual situation to formulate a more practical reference model, and corresponding engineering safety guarantee measures should be taken, which play an important role in ensuring construction safety and the quality of the completed bridge.

[0047] The present invention constructs a simulation analysis model with Ansys. The actual load is arranged on the upper chord of the Bailey beam 4 in the form of a uniformly distributed load, and the process of load change is simulated by setting load sub - steps, such as Figure 5 . In this test, surface strain gauges are arranged at the mid - span of the Bailey beam 4. Therefore, taking the mid - span stress as the independent variable, the functional relationship between it and the stress at one - eighth of the span of the Bailey beam 4 can be constructed. Through Ansys finite - element analysis, the functional relationship between the mid - span stress and the one - eighth stress of the Bailey beam 4 is: y = 0.552x + 0.078, where x is the mid - span stress of the Bailey beam 4, y is the stress at one - eighth of the span of the Bailey beam 4, and the unit is MPa. Substituting this functional relationship into the monitoring analysis, the theoretical stress change value at the location where no sensor is arranged can be obtained. By the above method, the Ansys model can be continuously used, taking the actual arrangement of sensors as the independent variable, to construct the functional relationship between other locations where no sensor is arranged and the measured values, so as to realize the monitoring and analysis of the overall monitored structure with a limited number of sensors.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limitations. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A real-time monitoring and evaluation system for bridges, characterized in that, it includes a first strain gauge installed in the mid-span bottom plate of the reinforced concrete box girder, second strain gauges respectively installed at the mid-span and the 1 / 4 span of the Bailey beam, a third strain gauge installed at the mid-span of the disc buckle support, a first temperature sensor installed at the mid-span of the Bailey beam, a second temperature sensor installed at the mid-span of the disc buckle support, and an anemometer installed on the disc buckle support. The first strain gauge, the second strain gauges, the third strain gauge, the first temperature sensor, the second temperature sensor, and the anemometer respectively send the collected real-time data to the data processing module through a collection and transmission instrument. The data processing module uses a finite element analysis model to obtain relevant parameters of other positions of the bridge based on the collected real-time data, then compares the collected real-time data and the relevant parameters of other positions of the bridge obtained by analysis with the warning thresholds respectively, and then evaluates the bridge according to the comparison results; The relevant parameters of other positions of the bridge obtained by the data processing module using the finite element analysis model based on the collected real-time data include: Through Ansys finite element analysis, the functional relationship between the stress at the mid-span of the Bailey beam and the stress at one-eighth of the Bailey beam is: y = 0.552x + 0.078, where: x is the stress at the mid-span of the Bailey beam, and y is the stress at one-eighth of the Bailey beam span.

2. The real-time monitoring and evaluation system for bridges according to claim 1, characterized in that, when the data processing module compares and obtains that the collected real-time data is greater than the warning threshold, it issues a warning message to remind the staff to investigate various influencing factors at the construction site, then modifies the finite element analysis model according to the on-site influencing factors, and then uses the modified finite element analysis model to analyze and evaluate the entire bridge based on the subsequent collected real-time data.

3. The real-time monitoring and evaluation system for bridges according to claim 1 or 2, characterized in that, the data processing module is a web application developed based on Python Dash.

4. The real-time monitoring and evaluation system for bridges according to claim 1 or 2, characterized in that, the first strain gauge is a vibrating wire concrete strain gauge buried in the mid-span bottom plate of the reinforced concrete box girder.

5. The construction method of the real-time monitoring and evaluation system for bridges according to claim 1 or 2 and its construction method, characterized in that, the second strain gauge is a vibrating wire surface strain gauge, and the second strain gauge and the first temperature sensor are fixedly installed on the longitudinal beam of the Bailey beam through glue.

6. The real-time monitoring and evaluation system for bridges according to claim 1 or 2, characterized in that, the third strain gauge is a vibrating wire surface strain gauge, the third strain gauge is fixedly installed on the disc buckle support by welding, the second temperature sensor is fixedly installed on the disc buckle support through glue, and the anemometer is fixedly installed on the disc buckle support by a buckle or by bundling.

7. A construction method of the real-time monitoring and evaluation system for bridges according to any one of claims 1-6, characterized in that, it includes placing a distribution box at a place where the reinforced concrete box girder is not easily disturbed by construction; then installing the collection and transmission instrument in the distribution box; before pouring concrete for the box girder, bury the first strain gauge into the mid-span bottom plate of the reinforced concrete box girder; Sandpaper is used to polish the surface of the longitudinal beam at the mid-span of the Bailey beam, and then the second strain gauge and the first temperature sensor are fixedly installed on the polished longitudinal beam of the Bailey beam by using adhesive. The third strain gauge is fixed on the disk buckle support by welding, the second temperature sensor is bonded on the disk buckle support by using adhesive, and the anemometer is fixed on the disk buckle support by using fasteners or ropes. The extension wires of the first strain gauge, the second strain gauge, the third strain gauge, the first temperature sensor, the second temperature sensor and the anemometer are respectively connected to the acquisition and transmission instrument; then the acquisition and transmission instrument is connected to the data processing module through the wireless communication unit, and the data processing module is used to perform real-time analysis and evaluation on the bridge according to the collected real-time data.

8. The construction method according to claim 7, characterized in that When embedding the first strain gauge, make a figure-eight knot on the cable at the outlet end of the first strain gauge, and then fix the first strain gauge on the steel bar at the mid-span bottom plate position.

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