Road steel-concrete composite beam bridge deck pavement anti-cracking performance detection method and system

Abstract

The invention relates to the technical field of crack resistance detection, in particular to a road steel-concrete composite beam bridge deck pavement crack resistance detection method and system which comprises a support, a test piece, a plurality of loading units and a bottom supporting and adjusting assembly. The bottom supporting and adjusting assembly comprises two bottom side edge supporting pieces, a bottom center supporting piece, two moving blocks and a plurality of connecting rods, the bottom side edge supporting pieces are driven to move through the moving blocks, the bottom center supporting piece is driven to move upwards and abut against and support the lower portion of the test piece through the action of the connecting rods, and meanwhile the bottom side edge supporting pieces on the two sides move downwards; then, only the lower central area of the test piece is supported, and at the moment, the two sides of the test piece can be subjected to a loading test through the upper loading unit; therefore, loading tests on the center and the two sides of the test piece can be carried out, rapid adjustment can be carried out in a linkage mode during switching, test data can be enriched, the test efficiency can be guaranteed, and crack resistance detection is more comprehensive.

Description

Technical Field

[0001] The present invention relates to the technical field of crack resistance detection, and in particular to a method and system for detecting the crack resistance performance of highway steel-concrete composite beam bridge deck pavement. Background Art

[0002] Highway steel-concrete composite beam bridges are a critical component of transportation infrastructure. Their deck pavements not only bear the dynamic loads of repeated vehicle traffic but also face the long-term challenges of complex and changing natural environmental factors, such as temperature fluctuations, humidity fluctuations, and ultraviolet radiation. The interaction of these factors can easily lead to stress concentration and damage accumulation within the pavement, which in turn causes cracking. Once cracks appear, they not only weaken the pavement's integrity and waterproofing, accelerating internal steel corrosion and structural degradation, but also further expand under vehicle loads, causing a decrease in bridge deck flatness and driving comfort. In severe cases, they may even cause serious problems such as spalling and potholes in the pavement, threatening the safety and stability of the bridge structure and the lives and property of traffic participants. Therefore, to ensure the crack resistance of the bridge deck, crack resistance testing is typically performed on bridge pavement specimens. These specimens are subjected to loading to determine if their crack resistance meets the requirements.

[0003] However, in the aforementioned prior art, the specimen is usually placed on a support and then subjected to a loading test. During the test, only one area of ​​the specimen is generally loaded, and the loading position cannot be flexibly changed, resulting in single data obtained and incomplete crack resistance testing. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for testing the crack resistance of highway steel-concrete composite beam bridge deck pavement, so as to solve the problem in the prior art that a specimen is usually placed on a support and then loaded and tested. During the test, only one area of ​​the specimen is generally loaded, and the loading position cannot be flexibly changed, resulting in single data obtained and incomplete crack resistance performance testing.

[0005] To achieve the above-mentioned object, the present invention provides a system for testing the crack resistance of highway steel-concrete composite beam bridge deck pavement, comprising a bracket, a test specimen, a plurality of loading units, and a bottom support adjustment assembly, wherein the plurality of loading units are sequentially arranged on the inner top wall of the bracket, and the test specimen is arranged below the loading units; The bottom support adjustment assembly includes two bottom side supports, a bottom center support, two moving blocks and multiple connecting rods. The two bottom side supports are both arranged inside the bracket and located below the specimen. The bottom center support is located between the two bottom side supports. The two moving blocks are respectively arranged below the corresponding bottom side supports. The two ends of the multiple connecting rods are respectively rotatably connected to the corresponding moving blocks and one side of the bottom center support. The multiple connecting rods are symmetrically distributed on both sides of the bottom center support.

[0006] Wherein, the bottom support adjustment assembly further includes two side adjustment units, and the two bottom side support members are respectively arranged on the corresponding side adjustment units; The side adjustment unit includes an adjustment bin, an adjustment component, a limiting mechanism and multiple lifting components. The adjustment bin is arranged below the specimen. The adjustment component is arranged on one side of the adjustment bin. The output end of the adjustment component passes through the adjustment bin and is fixedly connected to the bottom side support member. The bottom side support member has an arc surface and a plane. The limiting mechanism is arranged on the adjustment bin. Multiple lifting components are all arranged above the moving block. The output ends of multiple lifting components are all fixedly connected to the bottom of the adjustment bin.

[0007] The limiting mechanism includes a plurality of limiting components and a limiting arc plate, the plurality of limiting components are sequentially arranged below the regulating chamber, and the output ends of the plurality of regulating components are fixedly connected to the limiting arc plate.

[0008] Wherein, the bottom support adjustment assembly further comprises two lateral moving units, and the two lateral moving units are sequentially arranged on the two moving blocks; The lateral movement unit includes a lateral movement component, two threaded rods and a connecting block. The lateral movement component is arranged inside the bracket. The two threaded rods are symmetrically arranged at both ends of the connecting block. The other ends of the two threaded rods are rotatably connected to the bracket. The output end of the lateral movement component is fixedly connected to the corresponding threaded rod, and the threaded rod and the moving block are adapted to each other.

[0009] Among them, the bottom support adjustment assembly also includes two bottom slides, two sliders and a lifting slide. The two bottom slides are symmetrically arranged on the inner bottom wall of the bracket. One end of the two sliders is slidingly connected to the corresponding bottom slides, and the other ends of the two sliders are fixedly connected to the corresponding moving blocks. The lifting slide is arranged between the two bottom slides, and the bottom center support is slidingly connected to the lifting slide.

[0010] Wherein, the bottom support adjustment assembly further includes two linkage locking units, and the two linkage locking units are symmetrically arranged at both ends of the specimen; The linkage locking unit includes a pushing block, a first linkage block, a second linkage block, a locking block and multiple rebound mechanisms, the first linkage block and the second linkage block both have an oblique groove, the pushing block is arranged on one side of the moving block, the first linkage block is slidingly connected to the bracket, one end of the pushing block is adapted to the oblique groove of the first linkage block, one end of the first linkage block is adapted to the oblique groove of the second linkage block, the locking block is arranged at one end of the second linkage block, and the first linkage block and the second linkage block are both connected to the bracket through multiple rebound mechanisms.

[0011] Wherein, the rebound mechanism includes a spring and a telescopic rod, the two ends of the spring are movably connected to the bracket and the first moving block respectively, the two ends of the telescopic rod are fixedly connected to the bracket and the first moving block respectively, and the spring is sleeved on the outside of the telescopic rod.

[0012] Wherein, the loading unit includes a loading device and a loading plate. The loading device is arranged on the inner top wall of the bracket, and the output end of the loading device is fixedly connected to the loading plate.

[0013] The present invention also provides a method for detecting the crack resistance of a highway steel-concrete composite beam bridge deck pavement, which uses the above-mentioned highway steel-concrete composite beam bridge deck pavement crack resistance detection system and includes the following steps: Asphalt mixture was used to shape the specimens; Place the specimen support accurately, measure the support distance to be 200mm±0.5mm, then fix its position and place the specimen on the specimen support; Place the crack opening displacement measuring device in the center of the lower edge of the beam span and select the preset range; Connect the load cell and electronic strain extensometer to the data acquisition system or XY recorder; Start the loading unit and apply concentrated load at the center of the span at a preset rate of 50 mm / min; When the load drops to 80% of the peak load, the test is stopped, the cracking condition of the specimen is recorded, the load peak value and its corresponding crack opening displacement are read, the test results are analyzed and summarized, and recorded in the test report.

[0014] Among them, the process of molding the specimens using asphalt mixture specifically includes: According to the bridge deck pavement design plan, asphalt mixture rutting test molds were used to form test specimens, resulting in a combination of protective layer + adhesive layer + wearing layer. The test specimens were 300mm long, 300mm wide, and the height was the actual design thickness. The prismatic specimens were made by cutting method. The length of the specimens was 300mm±5.0mm, the width was 100mm±5.0mm, and the height was the actual design thickness. When forming the test piece, a crack with a length of 10mm±0.5mm was prefabricated at the bottom of the protective layer and pre-embedded with steel plates; Place the cut specimen in a pre-set constant temperature box and keep it warm at 15℃±0.5℃ for at least 5h. Use calipers to measure the size of the specimen at the mid-span and the two support sections. When the difference in height or width between the two support sections exceeds 2mm, the specimen should be discarded.

[0015] The present invention provides a method and system for detecting the crack resistance performance of highway steel-concrete composite beam bridge deck pavement. The bottom side support members are used to support the two side areas below the test piece. At this time, the upper loading unit applies a loading force to the middle area of ​​the test piece. After the test is completed, the bottom side support members are driven to move by the moving block. By relying on the action of the connecting rod, the bottom center support member is driven to move upward to support the bottom of the test piece. At the same time, the bottom side support members on both sides are moved downward again, thereby only supporting the lower center area of ​​the test piece. At this time, the upper loading unit can be used to perform a loading test on both sides of the test piece. In this way, the test piece can be subjected to loading tests at the center and both sides, and rapid adjustment can be performed through linkage when switching. This not only enriches the test data, but also ensures the test efficiency, making the crack resistance performance test more comprehensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art.

[0017] Figure 1 It is a structural schematic diagram of a highway steel-concrete composite beam bridge deck pavement crack resistance detection system of the present invention.

[0018] Figure 2 It is a cross-sectional view of the anti-cracking performance detection system for highway steel-concrete composite beam bridge deck pavement of the present invention.

[0019] Figure 3 The present invention Figure 2 A magnified view of the local structure at point A.

[0020] Figure 4 1 is a diagram showing the internal structure of the support of the present invention.

[0021] Figure 5 It is a structural schematic diagram of the prefabricated crack test piece of the present invention.

[0022] Figure 6It is a test piece and force diagram in the bridge deck pavement crack resistance testing method of the present invention.

[0023] Figure 7 It is a graph of the crack opening displacement under loading according to the present invention.

[0024] Figure 8 It is a flow chart of the steps of the method for detecting the anti-cracking performance of the highway steel-concrete composite beam bridge deck pavement of the present invention.

[0025] Figure 9 It is a specific flow chart of the present invention of using asphalt mixture to shape the test piece.

[0026] 1-bracket, 2-test piece, 3-bottom side support, 4-bottom center support, 5-moving block, 6-connecting rod, 7-adjusting bin, 8-adjusting component, 9-lifting component, 10-arc surface, 11-plane, 12-limiting component, 13-limiting arc plate, 14-lateral moving component, 15-threaded rod, 16-connecting block, 17-bottom slide, 18-slider, 19-lifting slide, 20-pushing block, 21-first linkage block, 22-second linkage block, 23-locking block, 24-bevel groove, 25-spring, 26-telescopic rod, 27-loading device, 28-loading plate, 29-electronic strain extensometer, 30-wear layer, 31-adhesive layer, 32-protective layer. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0028] See also Figures 1 to 4The present invention provides a highway steel-concrete composite beam bridge deck pavement crack resistance testing system, comprising a bracket 1, a test piece 2, a plurality of loading units and a bottom support adjustment assembly, wherein the bottom support adjustment assembly comprises two bottom side support members 3, a bottom center support member 4, two moving blocks 5 and a plurality of connecting rods 6, the bottom support adjustment assembly further comprises two side adjustment units, the side adjustment units comprise an adjustment bin 7, an adjustment component 8, a limiting mechanism and a plurality of lifting components 9, the limiting mechanism comprises a plurality of limiting components 12 and a limiting arc plate 13, the bottom support adjustment assembly The component also includes two lateral movement units, which include a lateral movement component 14, two threaded rods 15 and a connecting block 16. The bottom support adjustment assembly also includes two bottom slides 17, two sliders 18 and a lifting slide 19. The bottom support adjustment assembly also includes two linkage locking units, which include a pushing block 20, a first linkage block 21, a second linkage block 22, a locking block 23 and multiple rebound mechanisms. The rebound mechanism includes a spring 25 and a telescopic rod 26. The loading unit includes a loading device 27 and a loading plate 28.

[0029] Among them, multiple loading units are arranged in sequence on the inner top wall of the bracket 1, the specimen 2 is arranged below the loading unit, the two bottom side supports 3 are both arranged inside the bracket 1 and below the specimen 2, the bottom center support 4 is located between the two bottom side supports 3, and the two moving blocks 5 are respectively arranged below the corresponding bottom side supports 3. The two ends of multiple connecting rods 6 are respectively rotatably connected to the corresponding moving blocks 5 and one side of the bottom center support 4, and multiple connecting rods 6 are symmetrically distributed on both sides of the bottom center support 4. The bottom side support members 3 are used to support the two side areas below the specimen 2. At this time, the loading unit above applies a loading force to the middle area of ​​the specimen 2. After the test is completed, the bottom side support members 3 are driven to move by the moving block 5. By relying on the action of the connecting rod 6, the bottom center support member 4 is driven to move upward to support the bottom of the specimen 2. At the same time, the bottom side support members 3 on both sides are moved downward again, thereby only supporting the lower center area of ​​the specimen 2. At this time, the loading test can be performed on both sides of the specimen 2 through the loading unit above.

[0030] Secondly, the two bottom side support members 3 are respectively arranged on the corresponding side adjustment units; the adjustment chamber 7 is arranged below the specimen 2, and the adjustment component 8 is arranged on one side of the adjustment chamber 7. The output end of the adjustment component 8 passes through the adjustment chamber 7 and is fixedly connected to the bottom side support member 3. The bottom side support member 3 has an arc surface 10 and a plane 11. The limiting mechanism is arranged on the adjustment chamber 7. The plurality of lifting components 9 are all arranged above the moving block 5, and the output ends of the plurality of lifting components 9 are all fixedly connected to the bottom of the adjustment chamber 7. The adjusting chamber 7 is used to support the bottom side support members 3 inside, the adjusting member 8 is a self-locking motor, and the lifting member 9 is a self-locking cylinder; when the adjusting member 8 is started, it can drive the bottom side support members 3 to rotate, so that the arc surface 10 or the plane 11 thereof contacts the bottom of the specimen 2, and the contact areas of the arc surface 10 and the plane 11 with the specimen 2 are different, so the test data obtained are different, and more test data can be obtained; at the same time, after the adjustment of the bottom side support members 3 is completed, the limiting mechanism can be used for limiting the position; in addition, when the adjusting chamber 7 moves to both sides, the bottom center support member 4 moves up, and at this time the lifting member 9 is started, driving the adjusting chamber 7 to move down, so that the bottom side support members 3 no longer contact the specimen 2, thereby facilitating the loading unit above to perform a loading test on both sides of the specimen 2.

[0031] At the same time, a plurality of the limiting components 12 are sequentially arranged below the adjustment chamber 7, and the output ends of the plurality of the adjustment components 8 are fixedly connected to the limiting arc plate 13. The limiting component 12 is a self-locking cylinder. When the limiting component 12 is activated, it drives the limiting arc plate 13 to move upward, and then the arc surface 10 can adapt to the inner wall of the limiting arc plate 13 to achieve abutment and limitation, while the flat surface 11 can contact both sides of the limiting arc plate 13 to achieve abutment and limitation; thereby preventing the bottom side support member 3 from rotating accidentally when supporting the test piece 2.

[0032] In addition, the two lateral movement units are sequentially arranged on the two moving blocks 5; the lateral movement component 14 is arranged inside the bracket 1, and the two threaded rods 15 are symmetrically arranged at both ends of the connecting block 16. The other ends of the two threaded rods 15 are rotatably connected to the bracket 1. The output end of the lateral movement component 14 is fixedly connected to the corresponding threaded rod 15, and the threaded rod 15 and the moving block 5 are mutually adapted. The lateral movement component 14 is a self-locking motor. When the lateral movement component 14 is started, it relies on the action of the connecting block 16 to drive the two threaded rods 15 to rotate simultaneously, thereby driving the two moving blocks 5 adapted thereto to move in opposite directions. At this time, the moving block 5 drives the connecting rod 6 to move, and the connecting rod 6 drives the bottom center support member 4 to move upward, so that it contacts the bottom center area of ​​the specimen 2.

[0033] Then, the two bottom chutes 17 are symmetrically arranged on the inner bottom wall of the bracket 1. One end of the two sliders 18 is slidably connected to the corresponding bottom chutes 17, and the other end of the two sliders 18 is fixedly connected to the corresponding moving block 5. The lifting chute 19 is arranged between the two bottom chutes 17, and the bottom center support member 4 is slidably connected to the lifting chute 19. When the moving block 5 moves, the sliders 18 slide in the bottom chute 17, maintaining the stability of the moving block 5 and providing a certain degree of support for the moving block 5 and the entire lateral moving unit. In addition, the lifting chute 19 limits the up and down movement of the bottom center support member 4, maintaining the stability of the up and down sliding.

[0034] Again, the two linkage locking units are symmetrically arranged at both ends of the specimen 2; the first linkage block 21 and the second linkage block 22 both have an inclined groove 24, the pushing block 20 is arranged on one side of the moving block 5, the first linkage block 21 is slidingly connected to the bracket 1, one end of the pushing block 20 is mutually adapted to the inclined groove 24 of the first linkage block 21, one end of the first linkage block 21 is mutually adapted to the inclined groove 24 of the second linkage block 22, the locking block 23 is arranged at one end of the second linkage block 22, and the first linkage block 21 and the second linkage block 22 are both connected to the bracket 1 through multiple rebound mechanisms. When the moving block 5 moves, it drives the pushing block 20 to move, and then the pushing block 20 is adapted to the inclined slot 24 of the first linkage block 21, pushing the first linkage block 21 upward, and at the same time, the first linkage block 21 is adapted to the inclined slot 24 of the second linkage block 22, pushing the second linkage block 22 horizontally, thereby driving the locking block 23 close to the specimen 2, and finally the locking block 23 is adapted to the two ends of the specimen 2, thereby supporting and locking the specimen 2, and preventing the upper specimen 2 from shaking and deflecting when the bottom center support 4 is supporting; at this time, the lifting component 9 can be started, driving the adjustment chamber 7 to move downward, and then performing a loading test on both sides of the specimen 2; after the test is completed, the two moving blocks 5 shrink and move together, and at this time the rebound mechanism drives the first linkage block 21 and the second linkage block 22 to reset, so that the specimen 2 is separated from the locking block 23, and then relies on the bottom side support 3 for support again.

[0035] Furthermore, the two ends of the spring 25 are movably connected to the bracket 1 and the first movable block 5, respectively. The two ends of the telescopic rod 26 are fixedly connected to the bracket 1 and the first movable block 5, respectively. The spring 25 is sleeved on the outside of the telescopic rod 26. When the spring 25 rebounds, it drives the first linkage block 21 or the second linkage block 22 to move and reset. At the same time, the telescopic rod 26 follows the movement and expansion to maintain stability and support the first linkage block 21 and the second linkage block 22.

[0036] Finally, the loading device 27 is disposed on the inner top wall of the bracket 1, and the output end of the loading device 27 is fixedly connected to the loading plate 28. After the loading device 27 is started, it drives the loading plate 28 to move, thereby performing a loading test on the specimen 2.

[0037] When using a highway steel-concrete composite beam bridge deck pavement crack resistance detection system of this embodiment, the bottom side support members 3 are used to support the two side areas below the test piece 2. At this time, the upper loading unit applies a loading force to the middle area of ​​the test piece 2. At the same time, the adjusting component 8 is started to drive the bottom side support members 3 to rotate, so that the arc surface 10 or the plane 11 thereof contacts the bottom of the test piece 2. The contact areas of the arc surface 10 and the plane 11 with the test piece 2 are different, so the obtained test data are different, and more test data can be obtained. After the test is completed, the lateral moving unit drives the moving block 5 to move, so that the two adjusting chambers 7 are moved to the left and right. The two sides move, thereby driving the connecting rod 6, and the bottom center support member 4 moves upward under the drive of the connecting rod 6. At the same time, the pushing block 20 is adapted to the inclined slot 24 of the first linkage block 21, pushing the first linkage block 21 to move upward. At the same time, the first linkage block 21 is adapted to the inclined slot 24 of the second linkage block 22, pushing the second linkage block 22 to move horizontally, thereby driving the locking block 23 to approach the test piece 2, and finally the locking block 23 is adapted to both ends of the test piece 2; at this time, the lifting component 9 is started, driving the adjusting chamber 7 to move downward, so that the bottom side support member 3 is no longer in contact with the test piece 2, thereby facilitating the loading unit above to perform a loading test on both sides of the test piece 2; Through the above-mentioned structural setting, the specimen 2 can be subjected to loading tests at the center and both sides, and rapid adjustment can be made through linkage during switching, which not only enriches the test data but also ensures the test efficiency, making the crack resistance test more comprehensive.

[0038] See also Figures 5 to 9 The present invention also provides a method for detecting the crack resistance of highway steel-concrete composite beam bridge deck pavement, comprising the following steps: S1: Specimen 2 was formed using asphalt mixture; S101: According to the bridge deck pavement design, a test specimen 2 was formed using an asphalt mixture rutting test mold to obtain a composite test specimen 2 of protective layer 32 + adhesive layer 31 + wearing layer 30. The test specimen 2 was 300 mm long, 300 mm wide, and the height was the actual design thickness. S102: Use the cutting method to make prism specimen 2. Specimen 2 has a length of 300 mm ± 5.0 mm, a width of 100 mm ± 5.0 mm, and a height equal to the actual design thickness. S103: When forming specimen 2, a crack with a length of 10 mm ± 0.5 mm was prefabricated at the bottom of the protective layer, using a steel plate for pre-embedding; S104: Place the cut specimen 2 in a pre-set constant temperature box for insulation at 15°C ± 0.5°C for at least 5 hours. S105: Use calipers to measure the dimensions of specimen 2 at the mid-span and two support sections. If the difference in height or width between the two support sections exceeds 2 mm, specimen 2 shall be discarded.

[0039] S2: Place the support of specimen 2 accurately, measure the support distance to be 200mm±0.5mm, then fix its position and place specimen 2 on the support of specimen 2; S3: Place the crack opening displacement measuring device in the center of the lower edge of the beam span and select the preset measuring range; S4: Connect the load cell and the electronic strain extensometer 29 to the data acquisition system or XY recorder; S5: Start the loading unit and apply concentrated load at the center of the span at a preset rate of 50 mm / min; S6: When the load drops to 80% of the peak load, the test is stopped, the cracking condition of specimen 2 is recorded, the peak load value and its corresponding crack opening displacement are read, the test results are analyzed and summarized, and recorded in the test report.

[0040] Therefore, a double-layer composite structure is used as the test object, which is closer to the actual situation of bridge deck pavement, so as to scientifically test the crack resistance of bridge deck pavement; comprehensive detection indicators are proposed respectively for the ability of highway steel-concrete composite beam bridge deck pavement structure to resist the generation and expansion of microcracks in the actual working state, so that the test results are consistent with the test content; compared with the existing single indicator detection method, the detection method proposed by the present invention is more scientific, more comprehensive, clearer in working conditions, and has a high degree of discrimination; through the feedback of test results, the mix ratio design of pavement structure concrete and the functional ratio of pavement structure can be adjusted, thereby improving the crack resistance of the entire bridge deck pavement system.

[0041] Each test group shall consist of no less than three specimens 2. When the difference between a measured value and the average value of the same batch of specimens 2 is greater than k times the standard deviation, the measured value shall be discarded, and the average value of the remaining measured values ​​shall be used as the test result. The final number of valid specimens 2 shall be no less than three. When the number of specimens 2 is 4, 5, and 6, the k values ​​are 1.46, 1.67, and 1.82 respectively; The test results shall indicate the size of specimen 2, forming method, test temperature, loading rate, maximum load, crack initiation load, crack opening displacement, crack initiation toughness and instability toughness; According to the load and crack opening displacement data, a load-crack opening displacement curve is drawn, such as Figure 7 As shown. Based on the curve, the crack initiation toughness and instability toughness are calculated to obtain the crack resistance index of the test composite structure against microcracks and the crack resistance index of the microcrack extension ability; The instability toughness should be calculated according to formula (1): Where: —Instability toughness, ;P max —Extreme load, N; L—span of specimen 2, mm; h—height of specimen 2, mm; b—width of specimen 2, mm.

[0042] FⅠ(ac / h)—geometry factor, calculated according to formula (2): .

[0043] a c —Critical effective crack length, mm, calculated according to formula (3): Where: CMOD c —Extreme load P max The corresponding crack opening displacement is in mm.

[0044] E—calculated elastic modulus, MPa, calculated according to formula (4): ; Where: a0—initial crack length, mm; c i —The initial CMOD / P value of specimen 2, in mm / N, is calculated from the P and CMOD of any point on the straight line segment of the rising segment of the P-CMOD curve of specimen 2.

[0045] Crack initiation toughness The calculation should be performed according to formula (5): Where: —Instability toughness, ;P ini —Crack initiation load, N, is the load corresponding to the turning point where the rising section of the 2P-CMOD curve of the specimen changes from a straight line segment to a curved segment.

[0046] F I (a0 / h)—geometry factor, calculated according to formula (6): .

[0047] The above disclosure is merely one or more preferred embodiments of the present application and is not intended to limit the scope of the present application. A person skilled in the art will understand that all or part of the processes of the above embodiments and equivalent changes made in accordance with the claims of the present application are still within the scope of the present application.

Claims

1. A highway steel-concrete composite beam bridge deck pavement crack resistance testing system, comprising a bracket, a test specimen, and a plurality of loading units, wherein the plurality of loading units are sequentially arranged on the inner top wall of the bracket, and the test specimen is arranged below the loading units, characterized in that: Also included is a bottom support adjustment assembly; The bottom support adjustment assembly includes two bottom side supports, a bottom center support, two moving blocks and multiple connecting rods. The two bottom side supports are both arranged inside the bracket and located below the specimen. The bottom center support is located between the two bottom side supports. The two moving blocks are respectively arranged below the corresponding bottom side supports. The two ends of the multiple connecting rods are respectively rotatably connected to the corresponding moving blocks and one side of the bottom center support. The multiple connecting rods are symmetrically distributed on both sides of the bottom center support.

2. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 1, characterized in that: The bottom support adjustment assembly further includes two side adjustment units, and the two bottom side support members are respectively arranged on the corresponding side adjustment units; The side adjustment unit includes an adjustment bin, an adjustment component, a limiting mechanism and multiple lifting components. The adjustment bin is arranged below the specimen. The adjustment component is arranged on one side of the adjustment bin. The output end of the adjustment component passes through the adjustment bin and is fixedly connected to the bottom side support member. The bottom side support member has an arc surface and a plane. The limiting mechanism is arranged on the adjustment bin. Multiple lifting components are all arranged above the moving block. The output ends of multiple lifting components are all fixedly connected to the bottom of the adjustment bin.

3. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 2, characterized in that: The limiting mechanism includes a plurality of limiting components and a limiting arc plate. The plurality of limiting components are sequentially arranged below the regulating chamber, and the output ends of the plurality of regulating components are fixedly connected to the limiting arc plate.

4. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 3, characterized in that: The bottom support adjustment assembly further comprises two lateral movement units, and the two lateral movement units are sequentially arranged on the two movement blocks; The lateral movement unit includes a lateral movement component, two threaded rods and a connecting block. The lateral movement component is arranged inside the bracket. The two threaded rods are symmetrically arranged at both ends of the connecting block. The other ends of the two threaded rods are rotatably connected to the bracket. The output end of the lateral movement component is fixedly connected to the corresponding threaded rod, and the threaded rod and the moving block are adapted to each other.

5. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 4, characterized in that: The bottom support adjustment assembly also includes two bottom slides, two sliders and a lifting slide. The two bottom slides are symmetrically arranged on the inner bottom wall of the bracket. One end of the two sliders is slidably connected to the corresponding bottom slides, and the other ends of the two sliders are fixedly connected to the corresponding moving blocks. The lifting slide is arranged between the two bottom slides, and the bottom center support is slidably connected to the lifting slide.

6. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 5, characterized in that: The bottom support adjustment assembly further includes two linkage locking units, which are symmetrically arranged at both ends of the specimen; The linkage locking unit includes a pushing block, a first linkage block, a second linkage block, a locking block and multiple rebound mechanisms, the first linkage block and the second linkage block both have an oblique groove, the pushing block is arranged on one side of the moving block, the first linkage block is slidingly connected to the bracket, one end of the pushing block is adapted to the oblique groove of the first linkage block, one end of the first linkage block is adapted to the oblique groove of the second linkage block, the locking block is arranged at one end of the second linkage block, and the first linkage block and the second linkage block are both connected to the bracket through multiple rebound mechanisms.

7. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 6, characterized in that: The rebound mechanism includes a spring and a telescopic rod, the two ends of the spring are movably connected to the bracket and the first moving block respectively, the two ends of the telescopic rod are fixedly connected to the bracket and the first moving block respectively, and the spring is sleeved on the outside of the telescopic rod.

8. The highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 7, characterized in that: The loading unit includes a loading device and a loading plate. The loading device is arranged on the inner top wall of the bracket, and the output end of the loading device is fixedly connected to the loading plate.

9. A method for detecting the crack resistance of a highway steel-concrete composite beam bridge deck pavement, using the highway steel-concrete composite beam bridge deck pavement crack resistance detection system according to claim 8, characterized in that: The steps include: Asphalt mixture was used to shape the specimens; Place the specimen support accurately, measure the support distance to be 200mm±0.5mm, then fix its position and place the specimen on the specimen support; Place the crack opening displacement measuring device in the center of the lower edge of the beam span and select the preset range; Connect the load cell and electronic strain extensometer to the data acquisition system or XY recorder; Start the loading unit and apply concentrated load at the center of the span at a preset rate of 50 mm / min; When the load drops to 80% of the peak load, the test is stopped, the cracking condition of the specimen is recorded, the load peak value and its corresponding crack opening displacement are read, the test results are analyzed and summarized, and recorded in the test report.

10. The method for detecting crack resistance of highway steel-concrete composite beam bridge deck pavement according to claim 9, characterized in that: In the process of molding the test specimens using asphalt mixture, the following steps are specifically included: According to the bridge deck pavement design plan, asphalt mixture rutting test molds were used to form test specimens, resulting in a combination of protective layer + adhesive layer + wearing layer. The test specimens were 300mm long, 300mm wide, and the height was the actual design thickness. The prismatic specimens were made by cutting method. The length of the specimens was 300mm±5.0mm, the width was 100mm±5.0mm, and the height was the actual design thickness. When forming the test piece, a crack with a length of 10mm±0.5mm was prefabricated at the bottom of the protective layer and pre-embedded with steel plates; Place the cut specimens in a pre-set constant temperature box for insulation at 15°C ± 0.5°C. The insulation time should not be less than 5 hours. Use calipers to measure the size of the specimen at the mid-span and the two support sections. When the difference in height or width between the two support sections exceeds 2mm, the specimen should be discarded.

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