A device for detecting damage of a steel-concrete composite beam bridge deck pavement layer
Patent Information
- Application Number
- CN202521971292.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-12
- Publication Date
- 2026-09-04
- Estimated Expiration
- 2035-09-12
AI Technical Summary
由于钢材温度高、温度传导系数大，导致钢桥桥面铺装层温度高于普通路面20-30℃，在车辆荷载作用下，钢桥桥面铺装层使用寿命很短、使用质量差
[0020] 1. By studying the effects of different temperatures and wheel loads on the strain and rut depth of a scaled model of a steel-concrete composite beam bridge deck pavement, the effects of temperature and wheel load on the pavement layer of a steel-concrete composite beam bridge deck are realistically simulated.
Smart Images
Figure CN224719819U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of bridge deck pavement evaluation technology, and in particular to a device for detecting damage to the pavement layer of a steel-concrete composite beam bridge. Background Technology
[0002] Steel-concrete composite beams are a new type of structure that combines steel and concrete. Shear connectors (studs, channel steel, bent bars, etc.) are installed between the steel beams and concrete flanges to reduce relative slippage. Under vehicle loads, the internal mechanical behavior of bridge pavement systems differs significantly from that of ordinary asphalt pavements, and the stress on bridge pavement layers is more complex than that of ordinary pavements.
[0003] Steel beams are mainly composed of box-shaped structures made of various steel plates, which have significant advantages. However, steel is greatly affected by temperature; its thermal conductivity is much higher than that of cement concrete. In summer, the temperature of a steel bridge can reach 80-90℃ or even higher, making it unsafe to touch. Due to the high temperature and thermal conductivity of steel, the temperature of the pavement layer of a steel bridge is 20-30℃ higher than that of ordinary road surfaces. Under vehicle loads, the service life and quality of the pavement layer of a steel bridge are very short.
[0004] Currently, there are no specific methods for calculating damage to steel bridge deck pavement, no specific evaluation indicators, no specific test methods, and no corresponding testing devices. Using ordinary asphalt pavement standards to evaluate steel bridge pavement has a large range of variation and large errors, which brings a series of difficulties to actual engineering projects.
[0005] Existing evaluation methods have shortcomings, and new evaluation methods and accurate devices for detecting damage to the pavement layer of steel-concrete composite beam bridges are needed. Utility Model Content
[0006] The technical problem to be solved by this utility model is to provide a device for detecting damage to the pavement layer of steel-concrete composite beam bridge deck, which addresses the above-mentioned technical deficiencies.
[0007] The technical solution adopted by this utility model is: to provide a damage detection device for the pavement layer of a steel-concrete composite beam bridge deck, used for damage detection of a scaled model of the pavement layer of a steel-concrete composite beam bridge deck; characterized in that it includes:
[0008] An insulated box is used to cover a scaled model of the steel-concrete composite beam bridge deck pavement. The upper part of the insulated box has a fixed slide.
[0009] The wheels are slidably arranged relative to the fixed track, and the wheels roll and abut against the upper surface of the scaled model of the steel-concrete composite beam bridge deck pavement.
[0010] Two weight adjustment devices are located on both sides of the wheel. The wheel and the fixed slide are connected by the weight adjustment devices on both sides. The weight adjustment devices are slidably connected to the fixed slide. The weight adjustment devices are used to apply the downward pressure of the wheel on the scaled model of the steel-concrete composite beam bridge deck pavement.
[0011] A temperature regulating device is installed inside the insulation box;
[0012] The strain gauges are arranged in a plurality of units, which are spaced apart and parallel to the wheel sliding direction inside the scale model of the steel-concrete composite beam bridge deck pavement.
[0013] To further optimize this technical solution, the insulated box is a cuboid surrounded by six insulated panels. The insulated panel on the front of the insulated box is a movable door, and the insulated panel on top of the insulated box is a cover. The cover is fixed to the top of the insulated box by a fastener.
[0014] Further optimization of this technical solution also includes:
[0015] A reaction frame is installed inside the insulation box. The reaction frame includes a top seat on the upper side and several columns fixed below the top seat. The fixed slide is installed on the top seat.
[0016] To further optimize this technical solution, the weight adjustment device has a spring and a damper arranged side by side inside, and the spring is used to provide downforce to the wheel.
[0017] To further optimize this technical solution, the wheel adopts an integrated motor structure.
[0018] To further optimize this technical solution, the scaled model of the steel-concrete composite beam bridge deck pavement consists of, from top to bottom, an asphalt mixture upper layer, an asphalt mixture lower layer, a reinforced concrete layer, a steel bridge deck, and beam supports. Three strain gauges are placed between the reinforced concrete layer and the asphalt mixture lower layer.
[0019] The beneficial effects of this utility model are as follows:
[0020] 1. By studying the effects of different temperatures and wheel loads on the strain and rut depth of a scaled model of a steel-concrete composite beam bridge deck pavement, the effects of temperature and wheel load on the pavement layer of a steel-concrete composite beam bridge deck are realistically simulated.
[0021] 2. The weight adjustment device can change the load on the wheels, simulating the scene of a normal vehicle passing by, making the test results more realistic.
[0022] 3. The insulated box provides a sealed environment and uses a temperature regulation device to regulate the temperature inside the insulated box, providing a more realistic environment. Attached Figure Description
[0023] Figure 1 It is a device for detecting damage to the pavement layer of steel-concrete composite beam bridges.
[0024] Figure 2 This is a diagram of the internal structure of the weight adjustment device.
[0025] Figure 3 It is a diagram of the internal structure of the fixed track and the side of the wheel.
[0026] Figure 4 This is a scaled-down model structural diagram of the steel-concrete composite beam bridge deck pavement.
[0027] Figure 5 This is a side view of the pavement structure of a steel-concrete composite beam bridge.
[0028] Figure 6 It is a strain curve;
[0029] Explanation of markings in the diagram: 1. Insulation box; 101. Movable door; 1011. Hinge; 1012. Handle; 102. Cover plate; 1021. Fixture; 2. Reaction frame; 3. Temperature regulating device; 4. Fixed slide; 5. Wheel; 501. Tire; 502. Rotary motor; 503. Rotating shaft; 6. Weight adjusting device; 601. Spring; 602. Damper; 7. Asphalt mixture upper layer; 8. Asphalt mixture lower layer; 9. Reinforced concrete layer; 10. Steel bridge deck; 11. Beam support; 12. Strain gauge; 13. Shear stud. Detailed Implementation
[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0031] To keep the drawings concise, only the parts relevant to the utility model are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."
[0032] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0033] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0034] like Figure 1-6 As shown, a damage detection device for the pavement layer of a steel-concrete composite beam bridge deck is used to detect damage to a scaled-down model of the pavement layer of a steel-concrete composite beam bridge deck. It includes: an insulated box 1, used to cover the scaled-down model of the steel-concrete composite beam bridge deck, with a fixed slide rail 4 in the upper part of the insulated box 1; wheels 5, slidably disposed relative to the fixed slide rail 4, the wheels 5 rolling against the upper surface of the scaled-down model of the steel-concrete composite beam bridge deck; two weight adjustment devices 6, located on both sides of the wheels 5, the wheels 5 and the fixed slide rail 4 connected by the weight adjustment devices 6 on both sides, the weight adjustment devices 6 slidably connected to the fixed slide rail 4, the weight adjustment devices 6 being used to apply downward pressure from the wheels 5 on the scaled-down model of the steel-concrete composite beam bridge deck; a temperature adjustment device 3, disposed inside the insulated box 1; and several strain gauges 12, the strain gauges 12 being spaced apart parallel to the sliding direction of the wheels 5 inside the scaled-down model of the steel-concrete composite beam bridge deck.
[0035] The insulated box 1 is a cuboid surrounded by six insulated panels. The insulated panel on the front of the insulated box 1 is a movable door 101, and the insulated panel on the top of the insulated box 1 is a cover plate 102. The cover plate 102 is fixed to the top of the insulated box 1 by a fastener 1021.
[0036] It also includes: a reaction frame 2, which is installed inside the insulation box 1. The reaction frame 2 includes a top seat on the upper side and several columns fixed below the top seat. The fixed slide 4 is installed on the top seat.
[0037] The weight adjustment device 6 has a spring 601 and a damper 602 arranged side by side inside, and the spring 601 is used to provide downforce to the wheel 5.
[0038] The wheel 5 adopts an integrated motor structure.
[0039] The scaled model of the steel-concrete composite beam bridge deck pavement consists of, from top to bottom, an asphalt mixture upper layer 7, an asphalt mixture lower layer 8, a reinforced concrete layer 9, a steel bridge deck 10, and a beam support 11. Three strain gauges 12 are placed between the reinforced concrete layer 9 and the asphalt mixture lower layer 8.
[0040] In use, the reaction frame 2 is fixed inside the insulation box 1. The reaction frame 2 includes a top seat and a column. A fixed slide 4 is set on the top seat of the reaction frame 2, and the wheel 5 slides on the fixed slide 4. The fixed slide 4 and the wheel 5 are connected by a weight adjustment device 6. The top seat of the reaction frame 2 includes four longitudinal beams of the same length and two transverse beams of the same length. The length of the longitudinal beams is less than the width of the insulation box 1, and the length of the transverse beams is less than the length of the insulation box 1. The longitudinal beams are arranged in parallel, and the width after arrangement is less than the length of the insulation box 1. The two ends of the longitudinal beams are connected to the two transverse beams after arrangement. The longitudinal beams and transverse beams are perpendicular to each other. The height of the column is less than the height of the insulation box. The column is perpendicular to the bottom of the insulation box. The bottom of the column is connected by one transverse beam and two longitudinal beams.
[0041] The insulated box 1 is a cuboid surrounded by six insulation panels. The left, right, back and bottom of the insulated box are fixedly connected. The insulation panel on the front of the insulated box is a movable door 101. One side of the movable door 101 is connected to the left side of the insulated box 1 by a hinge 1011. A handle 1012 is provided on the outside of the other side of the movable door 101. The insulated box 1 is covered by an insulated box cover 1021, which is fixed to the top of the insulated box 1 by a fastener 1021.
[0042] The insulated box 1 of this invention provides a sealed environment, and the temperature inside the insulated box 1 is regulated by a temperature regulating device 3, providing a more realistic environment. The temperature regulating device 3 may include a heating module and a temperature control module to meet conventional heating requirements. Of course, a cooling module can also be added to meet a wider temperature range adjustment.
[0043] like Figure 2 As shown, the weight adjustment device 6 is internally equipped with a spring 601 and a damper 602. The downward pressure on the wheel 5 can be adjusted by replacing the spring 601 with different specifications, thus adjusting the load on the wheel 5. The dampers 602, arranged side-by-side, can be adapted to the springs 601 to reduce vibration, making the wheel 5 more stable when rolling on the scaled-down model of the steel-concrete composite beam bridge deck. The outer shell of the weight adjustment device 6 consists of upper and lower parts that are relatively movable. The damper 602 and spring 601 are located between the upper and lower parts. The upper part of the weight adjustment device 6 slides on a fixed track, and the lower part is connected to the wheel.
[0044] like Figure 3 As shown, the wheel 5 adopts an integrated motor structure. The wheel 5 includes a tire 501, and a rotary motor 502 is installed inside the tire 501. A rotary shaft 503 passes through the middle of the rotary motor 502, and the rotary shaft 503 is connected to the lower end of the weight adjustment device on both sides.
[0045] Tire 501 can slide on the fixed slide rail 4 and change the load size to simulate the scene of a normal vehicle passing by, making the test results more realistic.
[0046] The following description of the evaluation method for steel-concrete composite beam bridge deck pavement explains the application of this application, including the following steps:
[0047] S1. Prepare a device for detecting damage to the pavement layer of steel-concrete composite beam bridge deck.
[0048] S2. According to the asphalt mixture specification, such as Figure 4 As shown, at least nine scaled models of steel-concrete composite beam bridge deck pavement were fabricated. Each scaled model of steel-concrete composite beam bridge deck pavement includes an asphalt mixture upper layer 7, an asphalt mixture lower layer 8 below the asphalt mixture upper layer 7, a reinforced concrete layer 9 below the asphalt mixture lower layer 8, a steel bridge deck 10 below the reinforced concrete layer 9, and two beam supports 11 on both sides below the steel bridge deck 10. Three strain gauges 12 were placed between the reinforced concrete layer 9 and the asphalt mixture lower layer 8.
[0049] like Figure 5 As shown, the steel bridge deck 10 is connected to the reinforced concrete layer 9 using shear studs 13, and an adhesive waterproof layer is provided between the reinforced concrete layer 9 and the asphalt mixture lower layer 8.
[0050] The scaled-down model of the steel-concrete composite beam bridge deck pavement needs to be placed under the wheels. One bridge support of the scaled-down model is located at the movable door position, and the movable door of the insulation box can be closed. The height of the scaled-down model is the height that the insulation box 1 can be placed at; the width of the scaled-down model is the width that the insulation box 1 can be placed at; and the length of the scaled-down model is the length that the insulation box 1 can be placed at. When the reaction frame 2 can just fit into the insulation box 1, the height that the insulation box 1 can be placed at = the height of the reaction frame 2 - the height of the weight adjustment device 6 - the radius of the pulley; the width that the insulation box 1 can be placed at = the length of the reaction frame 2 - the length of the temperature adjustment device 3; and the width that the insulation box 1 can be placed at = the width of the reaction frame 2 - the width of the temperature adjustment device 3 (the above calculation method is for reference only; the specific parameters in the calculation method shall be based on the actual structure).
[0051] S3. Place the scaled model of the steel-concrete composite beam bridge deck pavement under the wheel 5 of the steel-concrete composite beam bridge deck pavement layer damage detection device; start the temperature adjustment device 3, set the temperature to 30℃, set the wheel load to 100N, and set the duration to 1 hour. After 1 hour, start the wheel 5 to rotate and slide from one side to the other side of the scaled model of the steel-concrete composite beam bridge deck pavement on the fixed slide rail 4 at a preset speed.
[0052] The wheel 5 slides in the middle of the asphalt mixture surface layer 7, from above one beam support 11 to above the other beam support 11.
[0053] After placing the scaled-down model of the steel-concrete composite beam bridge deck pavement into the steel-concrete composite beam bridge deck pavement layer damage detection device, the movable door 101 of the device is closed. Because steel bridges are significantly affected by temperature, which in turn affects the service life of the asphalt pavement, to ensure temperature stability during experiments on the scaled-down model of the steel-concrete composite beam bridge deck pavement, the preset temperature is maintained for one hour before the wheels are started to rotate, thus improving the accuracy of the evaluation results.
[0054] S4. When wheel 5 is sliding, use a data acquisition device to measure the reading of strain gauge 12 at preset time intervals, take the average strain value, and measure the rut depth after wheel 5 has finished sliding.
[0055] The data obtained in an experiment with different temperatures and wheel loads are the average strain over time under the set temperature and wheel load, and the rut depth under different temperatures and wheel loads.
[0056] S5. Continuously change the temperature to 40, 50, 60, 70, 80 and 90℃, each lasting for 1 hour. After 1 hour, start the wheel 5 to rotate within the preset time period and slide on the fixed slide rail 4. Repeat step S4. Based on the average strain value of different temperatures and different wheel loads over time, plot the strain curves under different temperatures and different wheel loads.
[0057] S6. Increase the wheel load by 100N and proceed to step S5.
[0058] like Figure 6 As shown, strain curves are plotted based on the obtained average strain values over time.
[0059] S7. Repeat step S6 until the wheel load increases to 1000N, and obtain the rut depth and strain curves over time under different temperatures and wheel loads.
[0060] S8. Determine the evaluation criteria based on the asphalt mixture damage rules and the rut depth and strain curves over time under different temperatures and wheel loads.
[0061] The scaled-down models of the steel-concrete composite girder bridge deck pavement were grouped. Based on the rut depth of each scaled-down model under different temperatures and wheel loads, the average rut depth of each group of scaled-down models under different temperatures and wheel loads was calculated. For example, if each group has 3 scaled-down models of the steel-concrete composite girder bridge deck pavement, and the rut depths of the 3 scaled-down models at a temperature of 30℃ and a wheel load of 100N are 3.7mm, 3.8mm, and 4.5mm respectively, then the average rut depth of this group is 4mm.
[0062] Based on the average rut depth of each group of steel-concrete composite beam bridge deck pavement scale model under different temperatures and different wheel loads, the average value is calculated, and the result is the final rut depth under different temperatures and different wheel loads.
[0063] Based on the strain curves of each scaled-down model of the steel-concrete composite beam bridge deck pavement under different temperatures and wheel loads over time, the average maximum strain of each scaled-down model of the steel-concrete composite beam bridge deck pavement under different temperatures and wheel loads is calculated. Based on the average maximum strain of each scaled-down model of the steel-concrete composite beam bridge deck pavement under different temperatures and wheel loads, the average maximum strain of each group of scaled-down models of the steel-concrete composite beam bridge deck pavement under different temperatures and wheel loads is calculated.
[0064] In the strain curves under different temperatures and wheel loads, the peak value (i.e., the maximum value) of the strain curve is the average maximum strain under different temperatures and wheel loads, such as... Figure 5 The strain curve at 30℃ shows that the average strain at 0.065s is the maximum average strain.
[0065] Based on the average maximum strain of each group of steel-concrete composite beam bridge deck pavement scale model under different temperatures and different wheel loads, the average value is calculated, and the result is the final average strain under different temperatures and different wheel loads.
[0066] According to the damage rules for asphalt mixtures, the tensile strain generated in the material is less than its own allowable strain. Once it exceeds the allowable strain, structural damage will occur. The allowable strain needs to be obtained through uniaxial compression tests. Generally, a maximum tensile strain within 10% of the allowable strain is considered as no damage or negligible damage; a maximum tensile strain between 10% and 20% of the allowable strain is considered as minor damage; a maximum tensile strain between 20% and 30% of the allowable strain is considered as some structural damage; and a maximum tensile strain between 30% and 50% of the allowable strain is considered as severe structural damage. Therefore, the maximum rutting depth (A) and maximum tensile strain (B) are used to evaluate the damage to the pavement layer of steel-concrete composite beam bridges.
[0067] The allowable strains corresponding to multiple scaled models of steel-concrete composite beam bridge deck pavement were obtained through uniaxial compression tests. The average value of multiple allowable strains was calculated to obtain the final allowable strain. The final allowable strain of the scaled model of steel-concrete composite beam bridge deck pavement in this invention was 4400 με through uniaxial compression tests. According to the asphalt mixture damage rules and data rounding principles, the maximum tensile strain values of the scaled model of steel-concrete composite beam bridge deck pavement in this invention at different stages are 450 με, 800 με, 1200 με and 2000 με, respectively.
[0068] As shown in Table 1, the average final strain values closest to the maximum tensile strain value were determined for different temperatures and wheel loads. The average final rut depth corresponding to these different temperatures and wheel loads was taken as the maximum rut depth. For example, the average final strain values close to the maximum tensile strain value of 450 με were 435.17 με, 451.63 με, and 448.0 με, respectively. The average final strain value of 435.17 με corresponds to a temperature of 40℃ and a wheel load of 400 N, with a corresponding rut depth of 4.32 mm. The average final strain value of 451.63 με corresponds to a temperature of 60℃ and a wheel load of 200 N, with a corresponding rut depth of 4.96 m. m; the final average strain of 448.0 με corresponds to a temperature of 30℃ and a wheel load of 700 N, and the corresponding rut depth at this temperature and wheel load is 5.12 mm; then the average value of the final rut depths corresponding to a temperature of 40℃ and a wheel load of 400 N, a temperature of 60℃ and different wheel loads of 200 N, and a temperature of 30℃ and a wheel load of 700 N is calculated, which is 4.8 mm. Based on the data rounding principle and the average value, the maximum rut depth is determined to be 5 mm.
[0069] Table 1. Evaluation Indicators for Pavement Layer of Steel-Concrete Composite Beam Bridges
[0070]
[0071] As shown in Table 2, the laboratory conducted multiple sets of evaluation index tests on the pavement of steel-concrete composite beam bridge decks (using the same type of pavement), with at least 3 parallel specimens in each set. The evaluation index tests on the pavement of steel-concrete composite beam bridge decks were conducted.
[0072] Table 2. Evaluation Criteria for Crack Propagation in Asphalt Pavements
[0073]
[0074] As shown in Table 3, in order to verify the reliability of this method, a specific test was also conducted on the pavement layer of another steel-concrete composite beam bridge. The test method was the same as that of this utility model, and the evaluation index was obtained.
[0075] Table 3. Evaluation Criteria for Crack Propagation in Asphalt Pavements
[0076]
[0077]
[0078] As shown in Table 3, the evaluation index of the pavement layer of the steel-concrete composite beam bridge deck changes very little. Therefore, the evaluation results obtained by applying the evaluation method of this utility model are stable and reliable.
[0079] It is understood that this utility model has been described through some embodiments, and those skilled in the art will know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this utility model.
Claims
1. A device for detecting damage to pavement layers of steel-concrete composite beam bridge decks, used for detecting damage to scaled-down models of pavement layers of steel-concrete composite beam bridge decks; characterized in that, include: Insulation box (1) is used to cover the scale model of the steel-concrete composite beam bridge deck pavement. The upper part of the insulation box (1) has a fixed slide (4). The wheel (5) is slidably set relative to the fixed slide rail (4), and the wheel (5) rolls against the upper end surface of the scaled model of the steel-concrete composite beam bridge deck pavement; Two weight adjustment devices (6) are located on both sides of the wheel (5). The wheel (5) and the fixed slide (4) are connected by the weight adjustment devices (6) on both sides. The weight adjustment devices (6) are slidably connected to the fixed slide (4). The weight adjustment devices (6) are used to apply the downward pressure of the wheel (5) on the scaled model of the steel-concrete composite beam bridge deck pavement. Temperature regulation device (3) is installed inside the heat preservation box (1); Strain gauges (12) are provided in a plurality of them, and the plurality of strain gauges (12) are arranged at intervals parallel to the sliding direction of the wheel (5) inside the scale model of the steel-concrete composite beam bridge deck pavement.
2. The device for detecting damage to the pavement layer of a steel-concrete composite beam bridge as described in claim 1, characterized in that, The insulated box (1) is a cuboid surrounded by six insulation boards. The insulation board on the front of the insulated box (1) is a movable door (101), and the insulation board on the top of the insulated box (1) is a cover plate (102). The cover plate (102) is fixed to the top of the insulated box (1) by a fastener (1021).
3. The device for detecting damage to the pavement layer of a steel-concrete composite beam bridge as described in claim 1, characterized in that, Also includes: The reaction frame (2) is installed inside the heat preservation box (1). The reaction frame (2) includes a top seat on the upper side and several columns fixed below the top seat. The fixed slide (4) is installed on the top seat.
4. The device for detecting damage to the pavement layer of a steel-concrete composite beam bridge as described in claim 1, characterized in that, The weight adjustment device (6) has a spring (601) and a damper (602) arranged side by side inside, the spring (601) being used to provide downforce to the wheel (5).
5. The device for detecting damage to the pavement layer of a steel-concrete composite beam bridge as described in claim 1, characterized in that, The wheel (5) adopts an integrated motor structure.
6. The device for detecting damage to the pavement layer of a steel-concrete composite beam bridge as described in claim 1, characterized in that, The scaled model of the steel-concrete composite beam bridge deck pavement consists of, from top to bottom, an asphalt mixture upper layer (7), an asphalt mixture lower layer (8), a reinforced concrete layer (9), a steel bridge deck (10), and a beam support (11). Three strain gauges (12) are placed between the reinforced concrete layer (9) and the asphalt mixture lower layer (8).