Intelligent test device and method for long-term load and corrosion of concrete filled steel tube arch rib member

Abstract

The invention relates to the field of concrete-filled steel tube structure mechanical property tests, in particular to a concrete-filled steel tube arch rib member long-term load and corrosion intelligent test device and method. The test device comprises: a corrosion tank covering the outside of a concrete-filled steel tube arch rib test piece and capable of being filled with or sprayed with a corrosive liquid; the load applying device comprises a plurality of load applying units, and each unit is used for applying long-term load to the concrete-filled steel tube arch rib test piece; the load applying unit comprises a screw rod, a nut, a loading end plate, a loading block and a force transmission block; the loading block penetrates through the corrosion tank and is tightly attached to the test piece, the force transmission block is located below the loading block and is tightly attached to the corrosion tank, and the multiple screws penetrate through the corrosion tank, so that the loading block can apply force to the concrete filled steel tube arch rib test piece; the sensor feeds back data to the data acquisition terminal in real time for processing, and the corrosion process is accurately controlled. According to the invention, the stress characteristics of the concrete-filled steel tube arch bridge under long-term load and corrosion effects can be simulated based on an intelligent technology.

Description

Technical Field

[0001] The present invention relates to the field of mechanical performance testing of steel tube concrete structures, and in particular to an intelligent testing device and method for long-term load and corrosion of steel tube concrete arch rib components. Background Art

[0002] During the service life of long-span CFST arch bridges, especially top-supported CFST arch bridges, CFST arch rib components are subject to long-term vertical loads applied at multiple points due to loads from the arch columns. Long-term vertical loads can easily cause shrinkage and creep of the core concrete of the arch ribs, leading to concrete cracks and stress redistribution across the cross-section of the arch rib components. This increases stress on the steel tubes and causes structural deformation, significantly impacting the overall mechanical properties of the structure, and thus its safety and durability. Therefore, long-term loads further complicate the working mechanism and stress characteristics of CFST arch bridges. At the same time, for long-span CFST arch bridge structures in offshore and coastal areas, CFST arch rib components are also subject to corrosion and other effects during their service life. Steel tube concrete arch ribs are exposed to the humid coastal environment for a long time and are easily corroded by corrosive media such as chloride ions, sulfates, and carbon dioxide, which leads to the destruction of the passivation film of the steel tube, rust of the steel tube, thinning of the wall thickness, reduction of the effective cross-section, weakening of the restraint effect on the core concrete, reducing the contact pressure between the steel tube and the core concrete, and thus weakening the bearing capacity of the structure; even during the service life of the steel tube concrete arch ribs, they may be affected by the combined effects of marine atmosphere, industrial atmosphere, and dry-wet cycle corrosion in the splash zone (mostly occurring at the arch foot), which will have an adverse effect on the safe service of the structure.

[0003] It can be seen that long-term loads and corrosion are key factors affecting the mechanical properties of CFST arch bridges in offshore and coastal areas. To clarify their working mechanism, a reasonable and feasible test device is urgently needed to conduct experimental studies on arched CFST structures under the coupled effects of "long-term load + corrosion". Commonly used "long-term load + corrosion" coupled test devices have the following inconveniences: First, existing long-term load test devices are mainly developed for linear CFST structures and are not suitable for applying long-term loads to arched CFST structures. In particular, it is difficult to simulate the long-term vertical loads transmitted to the arch ribs by the arch columns in top-decker CFST bridges. If a multi-point long bridge test loading system, reaction frame, and jack are used to apply long-term vertical loads to the arch ribs, there will be problems with the long-term use of the test system and jacks, which is not convenient for loading multiple specimens and has low efficiency. Second, it is difficult for existing test equipment to load the arch ribs to their ultimate bearing capacity without unloading the long-term vertical loads on the arch ribs. If the specimens are moved into a multi-point long bridge test loading system or other equipment for ultimate bearing capacity loading after the long-term loads are unloaded, it will be difficult to clarify the creep development mechanism of the steel tube concrete arch ribs under long-term loads, and thus it will be difficult to reveal the influence of long-term loads on the ultimate bearing capacity of the steel tube concrete arch ribs. Third, it is difficult for existing test equipment to apply spray corrosion (simulating dry-wet cycle corrosion in the splash zone) to the arch foot area of ​​the steel tube concrete arch ribs and salt spray corrosion (simulating marine atmospheric corrosion or industrial atmospheric corrosion) to the arch crown area at the same time, which deviates from the actual load or environmental conditions of the project. Fourth, it is difficult for existing test equipment to achieve precise and intelligent control of corrosion conditions such as the liquid level height and corrosion concentration of the corrosive liquid in the corrosion test of the steel tube concrete structure specimens in the corrosion tank, which restricts the precise realization of the test objectives.

[0004] In summary, there is an urgent need for a practical intelligent testing device to study the mechanical properties of steel tube concrete bridge arch rib components under long-term load + corrosion coupling. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiency of the existing test devices in the prior art that it is difficult to realize the test research of the mechanical properties of steel tube concrete arch rib components under the influence of long-term load and corrosion, and to provide a long-term load and corrosion intelligent test device and method for steel tube concrete arch rib components. The test device and test method can simulate the stress characteristics of steel tube concrete arch bridges under long-term load + corrosion, provide a stable and continuous loading environment, and reduce the problems of traditional test methods due to the limitations of time, site, load application mode and corrosion mode, which lead to the difficulty of testing, differences between load and corrosion environment conditions and actual projects. The present invention can effectively reproduce the mechanical behavior of actual steel tube concrete arch bridge projects in long-term service status under corrosive environments such as offshore and coastal areas, and provide more scientific and reliable test means for the optimization design, safety analysis and durability evaluation of bridges, thereby improving the service life and safety of engineering structures.

[0006] In a first aspect, the present invention provides an intelligent test device for long-term load and corrosion of concrete-filled steel tube arch rib components, comprising: A corrosion groove is coated on the outside of the steel tube concrete arch rib specimen, and the corrosion groove can be filled with or sprayed with a corrosion liquid; During the filling or spraying of the corrosive liquid, a limit sensor and a corrosive liquid concentration sensor are used to intelligently monitor the test. The limit sensor and the corrosive liquid concentration sensor are connected to a data acquisition terminal via external wires. The data acquisition terminal includes a data acquisition module and a computer data storage module, etc., and can be connected to an on-site or remote computer device through a wired connection, a Wi-Fi connection, or a wireless network card connection, so as to achieve real-time monitoring of the liquid level and concentration of the corrosive liquid in the corrosion tank, and the on-site or remote computer device can monitor and control the test; A load applying device, comprising a plurality of load applying units, each of the load applying units being used to apply a long-term load to the steel tube concrete arch rib specimen; Each of the load applying units includes a screw, a nut, a loading end plate, a loading block, and a force transmission block; The first end of the loading block is fixed to the loading end plate, and the second end of the loading block passes through the corrosion groove and fits tightly with the steel tube concrete arch rib specimen; The first end of the force transmission block is fixed to the loading end plate, and the second end of the force transmission block is located below the loading block and is tightly fitted with the corrosion groove; A plurality of screw rods are arranged through the corrosion grooves, and both ends of the screw rods are fixedly mounted on the loading end plates through the nuts, so that the loading block can exert force on the steel tube concrete arch rib specimen.

[0007] Preferably, the cross-sectional shape of the corrosion groove is consistent with the cross-sectional shape of the steel tube concrete arch rib specimen.

[0008] Preferably, the corrosion tank can be used as a cathode plate, with the inner surface of the corrosion tank connected to the cathode of an external DC power supply, and the steel tube concrete arch rib specimen connected to the anode of the external DC power supply. Data fed back to the data acquisition terminal by the limit sensor and the corrosion liquid concentration sensor is processed using on-site or remote computer equipment, and the results are fed back to the control terminal to achieve automatic control of the corrosion liquid level and concentration in the corrosion tank.

[0009] Preferably, the top of the corrosion groove symmetrically forms two inclined surfaces.

[0010] Preferably, the corrosion tank includes a salt spray nozzle and a spray head, the salt spray nozzle is arranged near the arch top of the steel tube concrete arch rib specimen, and the spray angle of the salt spray nozzle is arranged to be inclined upward, and the spray head is arranged near the arch foot of the steel tube concrete arch rib specimen, for spraying the corrosion liquid on the arch foot of the steel tube concrete arch rib specimen; The limit sensor and the corrosive liquid concentration sensor are arranged at the arch foot in the corrosion tank, and respectively monitor the liquid level and concentration of the corrosive liquid at the arch foot in the corrosion tank in real time; a salt mist concentration sensor is also arranged at the arch top in the corrosion tank, and the external wire of the salt mist concentration sensor is connected to the data acquisition terminal to monitor the salt mist concentration at the arch top in the corrosion tank in real time.

[0011] Preferably, the corrosion tank further includes a drain outlet, a water inlet pipe and a drain pipe, the salt spray nozzle and the spray head are connected to the water storage device through the water inlet pipe, the drain outlet is connected to the water storage device through the drain pipe, and the drain outlet is arranged at the bottom of the corrosion tank.

[0012] Preferably, the number of the screws is 2, 4, 6, 8, 10 or 12, and the screws are evenly distributed on the periphery of the loading block.

[0013] Preferably, each of the load applying units further includes a compressive load sensor, and the compressive load sensor is used to measure the magnitude of the compressive load applied by the load applying unit.

[0014] In a second aspect, the present invention provides a method for intelligently testing long-term load and corrosion of a concrete-filled steel tube arch rib member, comprising the following steps: S1: Install and fix the steel tube concrete arch rib specimen; S2: Cover the corrosion groove on the outside of the steel tube concrete arch rib specimen; S3: Pass the loading block through the corrosion groove and fit it tightly against the steel tube concrete arch rib specimen; place the force transmission block below the loading block and fit it tightly against the corrosion groove; pass the screw through the corrosion groove and fix it to the loading end plate with a nut so that the loading block can apply force to the steel tube concrete arch rib specimen; S4: Sealing the corrosion groove; S5: Pour the corrosive liquid into the corrosion tank, use the corrosion tank as a cathode plate, connect the inner surface of the corrosion tank to the cathode of an external DC power supply, connect the steel tube concrete arch rib specimen to the anode of the external DC power supply, and carry out an electrochemical accelerated corrosion test. At the same time, install a limit sensor and a corrosion liquid concentration sensor to monitor the liquid level and concentration of the corrosion liquid in real time; Alternatively, a salt spray nozzle is provided at the arch top near the concrete-filled steel tube arch rib specimen, with the spray angle of the salt spray nozzle being inclined upward, and a sprinkler head is provided at the arch foot near the concrete-filled steel tube arch rib specimen, and the arch top is subjected to salt spray corrosion through the salt spray nozzle, and the arch foot is subjected to dry-wet cycle corrosion through the sprinkler head. At the same time, a limit sensor and a corrosion liquid concentration sensor are installed to monitor the liquid level and concentration of the corrosion liquid at the arch foot in the corrosion tank in real time, and a salt spray concentration sensor is installed to monitor the salt spray concentration at the arch top in the corrosion tank in real time; S6: Record and analyze the stress, strain, deformation, corrosion degree and damage evolution of the structure during the test.

[0015] Preferably, in S3, the load size is applied by adjusting the tightness of the nut to simulate different load effects.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The test apparatus and test method of the present invention can simulate the stress characteristics of steel tube concrete arch bridges under long-term load and corrosion, provide a stable and continuous loading environment, and reduce the problems of traditional test methods due to limitations in time, site, load application method, and corrosion mode, such as the difficulty of testing, the difference between the load and corrosion environment conditions and the actual project. The present invention can effectively reproduce the mechanical behavior of actual steel tube concrete arch bridge projects under long-term service in corrosive environments such as offshore and coastal areas, providing a more scientific and reliable testing method for bridge optimization design, safety analysis, and durability evaluation, thereby improving the service life and safety of engineering structures.

[0017] 2. The present invention's screw-loaded long-term load-applying device is compact and capable of multi-point loading of concrete-filled steel tube arch ribs. Different long-term loads can be designed for each loading point based on the bridge's load-bearing characteristics. By adjusting the applied load magnitude through the tightening of an external nut, the device simulates the effects of different loads on the compressive deformation capacity of the component, enabling a more realistic reflection of the long-term load-bearing characteristics of concrete-filled steel tube long-span arch bridges. 3. The present invention's screw-loaded long-term load-applying device achieves internal and external connection of the specimen via loading end plates. It can also apply continuous long-term loads while conducting corrosion tests, simulating the actual load-bearing conditions of concrete-filled steel tube arch ribs. This provides a powerful reference for the load-bearing design of projects such as coastal long-span arch bridges. 4. Compared with traditional devices, the corrosion tank of the present invention has higher flexibility. It can realize corrosion test research of specimens in a shorter period through an external DC power supply. It can also realize corrosion test of specimens under various types of marine environments such as dry-wet cycle in seawater splash zone and marine atmospheric salt spray. In addition, the entire corrosion test process can be automatically monitored and controlled by a remote computer through an intelligent control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the "long-term load + electrochemical accelerated corrosion" test device in an embodiment of the present invention (taking a single-limb square steel tube concrete arch rib specimen as an example); Figure 2 1 is a front view of a single-limb square concrete-filled steel tube arch rib specimen according to an embodiment of the present invention; Figure 3 1 is a front view of a multi-limbed steel tube concrete truss hybrid structure arch rib specimen according to an embodiment of the present invention (taking a four-limbed steel tube concrete truss hybrid structure specimen as an example); Figure 4 is a cross-sectional view of a circular concrete-filled steel tube arch rib specimen according to an embodiment of the present invention (taking a standard circular cross-section concrete-filled steel tube as an example); Figure 5 is a cross-sectional view of a polygonal concrete-filled steel tube arch rib specimen according to an embodiment of the present invention (taking square-section concrete-filled steel tube as an example); Figure 6 Schematic diagram of the structure of the "long-term load + vault salt spray corrosion + arch foot dry-wet cycle corrosion" test device according to an embodiment of the present invention (taking a single-limb square steel tube concrete arch rib specimen as an example); Figure 7 This is a cross-sectional view of the corrosion tank device in the front view direction for the "salt spray corrosion of the arch crown + dry-wet cycle corrosion of the arch foot" test in an embodiment of the present invention; Figure 8 2. It is a cross-sectional view from the side of the corrosion tank device for the "salt spray corrosion of the arch crown + dry-wet cycle corrosion of the arch foot" test in an embodiment of the present invention; Figure 9 This is a schematic diagram of an embodiment of the present invention in which an ultimate bearing capacity test is directly carried out without unloading after the "long-term load + corrosion" test is completed; Figure 10 It is a flow chart of the real-time monitoring and feedback mechanism of the intelligent control system according to an embodiment of the present invention.

[0019] Markings in the figure: 1-steel tube concrete arch rib specimen; 2-corrosion tank; 201-salt spray nozzle; 202-sprinkler head; 203-drain outlet; 204-water inlet pipe; 205-drain pipe; 3-screw; 4-nut; 5-arch seat; 6-loading end plate; 7-loading block; 8-force transmission block; 9-corrosive liquid; 10-external DC power supply; 11-water storage device; 12-reaction frame; 13-jack; 14-compression load sensor; 15-limit sensor; 16-corrosive liquid concentration sensor; 17-salt spray concentration sensor; 18-data acquisition terminal. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0021] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or positional relationship, such as "upper", "lower", "left", "right", "center", "inside", and "outside", are based on the expressions of the orientation or positional relationship shown in the accompanying drawings, or are the orientation or positional relationship in which the invented product / device / apparatus is placed when it is conventionally used. These terms of orientation or positional relationship are merely for the purpose of facilitating the description of the scheme of the present invention or simplifying the description of the specific embodiments to facilitate the rapid understanding of the scheme by technicians, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship, and therefore should not be understood as limiting the present invention.

[0022] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simply understood that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", and "parallel", and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the solution of the present invention.

[0023] In addition, the expressions “first”, “second”, “third”, etc. in the terms are merely used to distinguish the description of the same or similar components, and should not be understood as emphasizing or implying the relative importance of specific components.

[0024] In addition, in the description of the embodiments of the present invention, "several," "plurality," and "a number" represent at least two. It can also be any number such as two, three, four, five, six, seven, eight, nine, or even more than nine.

[0025] Furthermore, in the description of the technical solution of the present invention, unless otherwise expressly specified, defined, or limited, the terms "disposed," "installed," "connected," "connected," "provided with," "laid," and "arranged" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections. They may be welded, riveted, bolted, threaded, or other commonly used connection methods in the art. Such connections may be mechanical, electrical, or communicative; they may be direct, indirect via an intermediate medium, or internally connected between two components.

[0026] Example 1 like Figure 1 As shown, a long-term load and corrosion intelligent testing device for steel tube concrete arch rib components includes a corrosion tank 2 and a load applying device.

[0027] The corrosion groove 2 is coated on the outside of the steel tube concrete arch rib specimen 1. The corrosion groove 2 can be filled with or sprayed with a corrosive liquid 9. The corrosive liquid 9 can corrode the steel tube concrete arch rib specimen 1. Then, the corrosion test of the steel tube concrete arch rib specimen 1 can be performed through the corrosion groove 2.

[0028] Wherein, the steel tube concrete arch rib specimen 1 includes a single-limb steel tube concrete arch rib specimen (such as Figure 2 As shown, circular steel tubes or polygonal steel tubes are used as the main load-bearing components of the arch structure), multi-legged steel tube concrete truss hybrid structure arch rib specimens (such as Figure 3 As shown, multi-limbed circular steel tubes or polygonal steel tubes are used as chords of the arch structure, and combined with steel webs to form the main load-bearing components). Circular steel tubes include but are not limited to standard circular ones (such as Figure 4 As shown), oval, etc., polygonal steel pipes include but are not limited to square (such as Figure 5 As shown in the figure), rectangle, hexagon, etc. Multi-limb steel tube concrete truss hybrid structure arch rib specimens include but are not limited to two-limb, three-limb, four-limb steel tube concrete arch rib structures, etc.

[0029] The present invention uses steel pipes with different cross-sectional shapes as the main load-bearing components of the arch bridge structure. It can balance the bearing capacity, construction difficulty and economy according to specific engineering requirements, and provide a reasonable optimization solution for the service performance of steel tube concrete arch rib components under long-term load and corrosion environment.

[0030] The corrosion groove 2 is covered on the outside of the steel tube concrete arch rib specimen 1, which means that the corrosion groove 2 at least covers a partial area of ​​the steel tube concrete arch rib specimen 1. For example, if the test only focuses on the middle part of the steel tube concrete arch rib specimen 1, then the corrosion groove 2 can only cover the middle part of the steel tube concrete arch rib specimen 1.

[0031] In an optional embodiment, the corrosion groove 2 may cover the entire area of ​​the steel tube concrete arch rib specimen 1, so that each position of the steel tube concrete arch rib specimen 1 can be uniformly corroded.

[0032] In an optional embodiment, the corrosion groove 2 can cover the arch top and arch foot areas of the steel tube concrete arch rib specimen 1. In this way, it is possible to apply spray corrosion (simulating dry-wet cycle corrosion in the splash zone) to the arch foot area of ​​the steel tube concrete arch rib specimen 1 while applying salt spray corrosion (simulating marine atmospheric corrosion or industrial atmospheric corrosion) to the arch top area.

[0033] Depending on the test requirements, the etching solution 9 can fill the etching tank 2 completely, and the filling rate of the etching solution 9 can be adjusted. Alternatively, a spraying device can be installed only at certain locations of the etching tank 2 for localized spraying. The etching solution 9 is regularly replaced or replenished to ensure a stable concentration. Different solutes and proportions of etching solution 9 can be used to simulate long-term corrosion under different environmental conditions.

[0034] The corrosion tank 2 described in the present invention has higher flexibility than traditional devices. It can realize corrosion test research on the specimen 1 in a shorter period through an external DC power supply 10. It can also be modified to realize corrosion impact tests of the specimen 1 under various types of marine environments such as dry-wet cycles in seawater splash zones and marine atmospheric salt spray.

[0035] In one or more embodiments, the steel tube concrete arch rib specimen 1 is mounted on and fixed to the arch seat 5, and the corrosion groove 2 is firmly wrapped around the outside of the steel tube concrete arch rib specimen 1. Both ends of the corrosion groove 2 can also be fixed to the arch seat 5. In a preferred embodiment, the corrosion groove 2 should be sealed to prevent the corrosion liquid 9 from flowing out and causing environmental damage.

[0036] The load applying device includes a plurality of load applying units, each of which is used to apply a long-term load to the steel tube concrete arch rib specimen 1, thereby enabling multi-point loading of the steel tube concrete arch rib specimen 1.

[0037] The position and number of the load applying units are consistent with the position and number of the columns on the arch of the steel tube concrete arch rib specimen 1, so as to truly simulate the long-term stress conditions of the steel tube concrete arch rib specimen 1.

[0038] Each of the load applying units includes a screw 3 , a nut 4 , a loading end plate 6 , a loading block 7 , and a force transmission block 8 , and a long-term load is applied to the steel tube concrete arch rib specimen 1 through the loading block 7 .

[0039] There are two loading end plates 6, one of which is fixedly connected to the loading block 7, and the other is fixedly connected to the force transmission block 8. In an optional embodiment, the loading block 7 can be welded to the center of one loading end plate 6, and the force transmission block 8 can be welded to the center of the other loading end plate 6.

[0040] The loading block 7 is located above the steel tube concrete arch rib specimen 1, the first end of the loading block 7 is fixed to the loading end plate 6, and the second end of the loading block 7 passes through the corrosion groove 2 and fits tightly with the steel tube concrete arch rib specimen 1. Therefore, the shape of the second end of the loading block 7 should be consistent with the external shape of the steel tube concrete arch rib specimen 1, and the shape of the second end of the loading block 7 should be cut according to the curvature of the steel tube concrete arch rib specimen 1.

[0041] The force transmission block 8 is located directly below the loading block 7. The first end of the force transmission block 8 is fixed to the loading end plate 6. The second end of the force transmission block 8 is tightly fitted with the corrosion groove 2. Therefore, the shape of the second end of the force transmission block 8 should be consistent with the external shape of the corrosion groove 2. The shape of the second end of the force transmission block 8 should be cut according to the curvature of the corrosion groove 2.

[0042] Multiple screw rods 3 are provided through the corrosion groove 2, and both ends of the screw rods 3 are fixed to the loading end plate 6 via the nuts 4. That is, multiple screw rods 3 are arranged on the periphery of the loading block 7 and the force transmission block 8. Through the cooperation of the screw rods 3 and the nuts 4, the loading block 7 can be pressed against the top of the steel tube concrete arch rib specimen 1, and the force transmission block 8 can be pressed against the bottom of the corrosion groove 2, so that the loading block 7 can apply force to the steel tube concrete arch rib specimen 1.

[0043] In a preferred solution, the number of the screws 3 is 2, 4, 6, 8, 10 or 12, and the screws 3 are evenly distributed on the periphery of the loading block 7, thereby facilitating uniform loading of the loading block 7. In a preferred solution, the loading block 7 and the screw 3 inside the corrosion tank 2 are sprayed with waterproof paint.

[0044] In a preferred solution, the installation method of the load applying unit is as follows: The loading block 7 and force transfer block 8 were cut and processed according to the curvature of the steel tube concrete arch rib specimen 1 and the corrosion trough 2 at the designed loading location. The loading block 7 was welded to the center of the upper loading end plate 6, and the force transfer block 8 was welded to the center of the lower loading end plate 6. The cutting and processing shapes of the loading block 7 and force transfer block 8 were designed according to the corresponding dimensions of the steel tube concrete arch rib specimen 1 and the corrosion trough 2. It was necessary to ensure that the processed loading block 7 and force transfer block 8 could closely fit the designed loading positions of the steel tube concrete arch rib specimen 1 and the corrosion trough 2 respectively during the long-term load application process. The screw 3 and loading block 7 were passed through the pre-drilled area of ​​the corrosion trough 2. The loading block 7 passed through the corrosion trough 2 and applied to the designed position of the steel tube concrete arch rib specimen 1, while the force transfer block 8 applied to the designed position of the corrosion trough 2. The loading block 7 and screw 3 inside the corrosion trough 2 were sprayed with waterproof paint. The nut 4 was tightened until the designed long-term load could be applied to the specimen, and the long-term load test study began.

[0045] By adjusting the tightness of the nut 4, the size of the load loaded by the loading block 7 can be adjusted, thereby simulating the influence of different loads on the compressive deformation capacity of the steel tube concrete arch rib specimen 1, and more realistically reflecting the long-term bearing characteristics of the steel tube concrete large-span arch bridge.

[0046] In an optional embodiment, each of the load applying units further includes a compressive load sensor 14 , which is used to measure the size of the compressive load applied by the load applying unit, thereby facilitating adjustment of the size of the load applied by the loading block 7 .

[0047] The long-term load application device based on screw loading of the present invention is compact and can realize multi-point loading of the steel tube concrete arch rib member 1. Different long-term loads can be designed for each loading point according to the load characteristics of the bridge. The function of adjusting the applied load size by loosening and tightening the external nut 4 simulates the influence of different loads on the compressive deformation capacity of the member, which can more realistically reflect the long-term load-bearing characteristics of the steel tube concrete long-span arch bridge. The present invention is based on a long-term load application device for screw loading, which realizes the internal and external connection of the test piece through the loading end plate 6. It can also apply continuous long-term load while conducting corrosion tests to simulate the actual load-bearing conditions of steel tube concrete arch rib components, providing a strong reference basis for the load-bearing design of coastal large-span arch bridges and other projects.

[0048] The test apparatus and test method of the present invention can simulate the stress characteristics of a steel tube concrete arch bridge under long-term load and corrosion, providing a stable and continuous loading environment. This reduces the difficulties inherent in traditional testing methods due to limitations in time, site, load application method, and corrosion mode, as well as the differences between the load and corrosion environment conditions and actual projects. The present invention can effectively reproduce the mechanical behavior of actual steel tube concrete arch bridges in long-term service under corrosive environments such as offshore and coastal areas, providing a more scientific and reliable testing method for bridge optimization design, safety analysis, and durability assessment, thereby improving the service life and safety of engineering structures.

[0049] The new arched concrete-filled steel tube (CFST) long-term load and corrosion testing device and method proposed in this paper are capable of simulating diverse scenarios and accurately reflecting the deformation resistance and corrosion resistance of CFST long-span arch bridge structures during long-term operation. This not only provides a valuable reference for bridge design and construction, but also features a simple design and easy assembly, significantly lowering the research threshold. It provides a reliable testing method for durability assessment, service life prediction, and optimized design of CFST arch rib components, possessing significant engineering application value and academic research significance.

[0050] Example 2 Based on Example 1, this example further illustrates the etching groove 2.

[0051] like Figure 1 、 Figure 10 As shown, in this embodiment, the cross-sectional shape of the corrosion tank 2 is consistent with the cross-sectional shape of the steel tube concrete arch rib specimen 1. For example, the cross-sectional shapes of the corrosion tank 2 and the steel tube concrete arch rib specimen 1 are both square to ensure uniform corrosion. The corrosion tank 2 can be used as a cathode plate. The inner surface of the corrosion tank 2 is connected to the cathode of an external DC power supply 10, and the steel tube concrete arch rib specimen 1 is connected to the anode of the external DC power supply 10. The electrochemical accelerated corrosion test is carried out using the corrosion tank 2 instead of the cathode plate. The limit sensor 15 and the corrosion liquid concentration sensor 16 in the corrosion tank 2 are connected to the data acquisition terminal 18 by external wires to monitor the liquid level and concentration of the corrosion liquid 9 in the corrosion tank 2 in real time.

[0052] In a preferred solution, the corrosion tank 2 is a steel corrosion tank 2.

[0053] In a specific test, when conducting an electrochemical accelerated corrosion test, the corrosion liquid 9 can be poured into the corrosion tank 2, and then the external DC power supply 10 is connected. The corrosion test research of the specimen 1 can be realized in a relatively short period through the external DC power supply 10.

[0054] In addition, the data fed back to the data acquisition terminal 18 by the limit sensor 15 and the corrosive liquid concentration sensor 16 are processed by the computer and the results are fed back to the control terminal, so that the liquid level and concentration of the corrosive liquid 9 in the corrosion tank 2 can be automatically controlled. If the liquid level of the corrosive liquid 9 is higher or lower than the range set by the computer, the corrosive liquid 9 can be automatically extracted or replenished through the drain pipe 205 or the water inlet pipe 204 respectively; if the concentration of the corrosive liquid 9 is higher or lower than the range set by the computer, the diluted or high-concentration corrosive liquid 9 can be automatically replenished into the corrosion tank 2 through the water inlet pipe 204 respectively; if the loading time of the long-term load continues, the concentration of the corrosive liquid 9 is significantly lower than the range set by the computer, the corrosive liquid 9 in the corrosion tank 2 can be regularly extracted through the drain pipe 205 and new corrosive liquid 9 can be replenished through the water inlet pipe 204 until the requirements are met.

[0055] Example 3 Based on Example 1, this example further illustrates the etching groove 2.

[0056] like Figure 6 、 Figure 7 、 Figure 8 、 Figure 10 As shown, in this embodiment, the top of the corrosion groove 2 is provided with a sharp corner and two symmetrically formed inclined surfaces to ensure that the cold condensed water formed by the corrosive salt mist at the top can flow down along the inclined top and is not likely to drip directly onto the test piece, thereby avoiding the condensed salt water corrosion effect that does not exist in actual salt mist corrosion conditions. The shape of the sides and bottom of the corrosion groove 2 is not strictly limited.

[0057] The corrosion tank 2 includes a salt spray nozzle 201 , a spray head 202 , a drain port 203 , a water inlet pipe 204 and a drain pipe 205 .

[0058] A salt spray nozzle 201 is installed at the upper side of the corrosion tank 2, near the specimen arch, to protect the arch from salt spray corrosion while preventing direct corrosion by condensed salt water. The spray angle of the salt spray nozzle 201 is adjusted to spray obliquely upward from the specimen, thereby preventing the formation of cold condensed water on the specimen surface. A spray head 202 is installed at the lower side of the corrosion tank 2, near the specimen arch foot, to spray corrosive liquid 9 directly onto the specimen arch foot, simulating the dry-wet cycle corrosion of the arch foot in the wave splash zone. A drain port 203 is provided at the bottom of the left and right sides of the corrosion tank 2 to drain excess corrosive liquid 9. A water storage device 11 is provided, and the salt spray nozzle 201 and the spray head 202 are connected to the water storage device 11 via a water inlet pipe 204. The drain port 203 is connected to the water storage device 11 via a drain pipe 205. The limit sensor 15 and the corrosive liquid concentration sensor 16 at the arch foot of the corrosion tank 2 are connected to the data acquisition terminal 18 through external wires to respectively monitor the liquid level and concentration of the corrosive liquid 9 at the arch foot of the corrosion tank 2 in real time. The salt mist concentration sensor 17 at the dome in the corrosion tank 2 is connected to the data acquisition terminal 18 through an external wire to monitor the salt mist concentration at the dome in the corrosion tank 2 in real time.

[0059] In the specific test, when conducting the arch crown salt spray corrosion + arch foot dry-wet cycle corrosion test, the corrosive liquid 9 is poured into the external water storage device 11, and then flows to the salt spray nozzle 201 and the spray head 202 through the water inlet pipe 204, so as to achieve spray corrosion (simulating dry-wet cycle corrosion in the splash zone) on the arch foot area of ​​the steel tube concrete arch rib while applying salt spray corrosion (simulating marine atmospheric corrosion or industrial atmospheric corrosion) to the arch crown area, truly simulating the impact of corrosion on the arch rib structure of large-span arch bridges in coastal areas.

[0060] In addition, the salt mist concentration sensor 17 monitors the salt mist concentration in the corrosion tank 2 in real time, converts the measured data into an electrical signal, and feeds it back to the data acquisition terminal 18. The computer processes the data and compares it with the pre-set test salt mist concentration range. If the actual detected salt mist concentration is lower than the set range, the data acquisition terminal 18 will automatically calculate the volume of the corrosive liquid 9 that needs to be replenished, generate a control instruction, extract the corrosive liquid 9, and transport it to the salt mist nozzle 201 through the water inlet pipe 204 for spraying. The spraying amount is precisely controlled based on the calculated volume of the corrosive liquid 9 that needs to be replenished. This test device can realize the automated monitoring and control of salt mist corrosion in the steel tube concrete arch rib vault area, and more accurately control the test conditions to simulate actual working conditions.

[0061] Example 4 A method for intelligently testing long-term load and corrosion of concrete-filled steel tube arch rib components, using the intelligent testing device for long-term load and corrosion of concrete-filled steel tube arch rib components as described in Example 2, comprises the following steps: S1: Install and fix the steel tube concrete arch rib specimen 1.

[0062] Among the options available, based on engineering test requirements, select the appropriate cross-sectional form of the inner and outer steel pipes, determine the steel pipe material, dimensions, and wall thickness, and design a reasonable arch curvature radius. Pour the core concrete within the outer steel pipe, using layered pouring and multiple vibrations to ensure concrete density. Curing the concrete to the design strength ensures the synergistic performance of the steel pipe and concrete. Then, determine the loading position and load magnitude of the long-term load device based on the design requirements of the underlying project.

[0063] According to the design drawings, on-site layout is carried out in the laboratory to determine the installation position of the steel tube concrete arch rib specimen 1, and the support points of the specimen and the installation position of the fixed arch seat are accurately calibrated to ensure the accuracy of the structural installation.

[0064] Arrange the arch seat 5 on the test platform in advance to ensure that the stiffness of the arch seat 5 meets the loading requirements. Install the steel tube concrete arch rib specimen 1 on the arch seat 5 according to the layout position and fix it to ensure accurate positioning and axis alignment.

[0065] S2: Cover the corrosion groove 2 on the outside of the steel tube concrete arch rib specimen 1.

[0066] In an optional solution, the corrosion groove 2 is manufactured according to the dimensions and parameters of the designed specimen 1 to ensure its rigidity, corrosion resistance, and sealing properties. The corrosion groove 2 is securely wrapped around the exterior of the arch rib specimen 1, and pre-drilled holes are added at the designed locations to ensure that the screw 3 and loading block 7 of the long-term load test device can pass through the corrosion groove 2 at the designated locations.

[0067] S3: The loading block 7 is passed through the corrosion groove 2 and fits tightly with the steel tube concrete arch rib specimen 1; the force transmission block 8 is set below the loading block 7 and fits tightly with the corrosion groove 2; the screw 3 is passed through the corrosion groove 2 and fixed to the loading end plate 6 by the nut 4, so that the loading block 7 can apply force to the steel tube concrete arch rib specimen 1. The load size is adjusted by the tightness of the nut 4 in S3, which can simulate different load effects. In an optional embodiment, each of the load applying units also includes a pressure load sensor 14, which is used to measure the pressure load size applied by the load applying unit, so as to facilitate the adjustment of the load size loaded by the loading block 7.

[0068] S4: sealing the corrosion groove 2; optionally, using epoxy resin to seal the gaps in the corrosion groove 2.

[0069] S5: Pour the corrosive liquid 9 into the corrosion tank 2, use the corrosion tank 2 as a cathode plate, connect the inner surface of the corrosion tank 2 to the cathode of the external DC power supply 10, connect the steel tube concrete arch rib specimen 1 to the anode of the external DC power supply 10, and carry out the electrochemical accelerated corrosion test; regularly replace or replenish the corrosive liquid 9 to ensure its concentration stability. Corrosive liquids 9 with different solutes and mix ratios can be used to simulate long-term corrosion under different environmental conditions. At the same time, a limit sensor 15 and a corrosive liquid concentration sensor 16 are installed to monitor the liquid level and concentration of the corrosive liquid 9 in real time.

[0070] S6: Record and analyze the stress, strain, deformation, corrosion degree and damage evolution of the structure during the test.

[0071] After the long-term load + corrosion test begins, the system uses necessary sensor monitoring and other means to record information from the pressure load sensor 14, limit sensor 15, corrosive fluid concentration sensor 16, and other monitoring devices. If the liquid level and concentration of the corrosive fluid 9 do not meet the requirements during the corrosion test, the intelligent system automatically adjusts the level. If the load drops during the long-term load period, the system promptly reloads the structure. During the test, the system monitors the stress, strain, deformation, corrosion level, and damage evolution of the structure in real time, obtaining scientific test data that provides a theoretical basis for structural optimization design and durability assessment.

[0072] In an optional embodiment, if Figure 9 As shown, by adding a reaction frame 12 and a jack 13, the present invention can directly carry out the ultimate bearing capacity test without unloading after the "long-term load + corrosion" test is completed, thereby making it easier to clarify the creep development mechanism of the steel tube concrete arch rib under long-term load, and further revealing the influence of long-term load on the ultimate bearing capacity of the steel tube concrete arch rib.

[0073] Example 5 A method for intelligently testing long-term load and corrosion of concrete-filled steel tube arch rib components, using the intelligent testing device for long-term load and corrosion of concrete-filled steel tube arch rib components as described in Example 3, comprises the following steps: S1: Install and fix the steel tube concrete arch rib specimen 1.

[0074] Among the options available, based on engineering test requirements, select the appropriate cross-sectional form of the inner and outer steel pipes, determine the steel pipe material, dimensions, and wall thickness, and design a reasonable arch curvature radius. Pour the core concrete within the outer steel pipe, using layered pouring and multiple vibrations to ensure concrete density. Curing the concrete to the design strength ensures the synergistic performance of the steel pipe and concrete. Then, determine the loading position and load magnitude of the long-term load device based on the design requirements of the underlying project.

[0075] According to the design drawings, on-site layout is carried out in the laboratory to determine the installation position of the steel tube concrete arch rib specimen 1, and the support points of the specimen and the installation position of the fixed arch seat are accurately calibrated to ensure the accuracy of the structural installation.

[0076] Arrange the arch seat 5 on the test platform in advance to ensure that the stiffness of the arch seat 5 meets the loading requirements. Install the steel tube concrete arch rib specimen 1 on the arch seat 5 according to the layout position and fix it to ensure accurate positioning and axis alignment.

[0077] S2: Cover the corrosion groove 2 on the outside of the steel tube concrete arch rib specimen 1.

[0078] In an optional solution, the corrosion groove 2 is manufactured according to the dimensions and parameters of the designed specimen 1 to ensure its rigidity, corrosion resistance, and sealing properties. The corrosion groove 2 is securely wrapped around the exterior of the arch rib specimen 1, and pre-drilled holes are added at the designed locations to ensure that the screw 3 and loading block 7 of the long-term load test device can pass through the corrosion groove 2 at the designated locations.

[0079] S3: The loading block 7 is passed through the corrosion groove 2 and fits tightly with the steel tube concrete arch rib specimen 1; the force transmission block 8 is set below the loading block 7 and fits tightly with the corrosion groove 2; the screw 3 is passed through the corrosion groove 2 and fixed to the loading end plate 6 by the nut 4, so that the loading block 7 can apply force to the steel tube concrete arch rib specimen 1. The load size is adjusted by the tightness of the nut 4 in S3, which can simulate different load effects. In an optional embodiment, each of the load applying units also includes a pressure load sensor 14, which is used to measure the pressure load size applied by the load applying unit, so as to facilitate the adjustment of the load size loaded by the loading block 7.

[0080] S4: sealing the corrosion groove 2; optionally, using epoxy resin to seal the gaps in the corrosion groove 2.

[0081] S5: A salt spray nozzle 201 is set at the arch top near the steel tube concrete arch rib specimen 1, and the spray angle of the salt spray nozzle 201 is set to be inclined upward. A spray head 202 is set at the arch foot near the steel tube concrete arch rib specimen 1. Salt spray corrosion is performed on the arch top through the salt spray nozzle 201, and dry-wet cycle corrosion is performed on the arch foot through the spray head 202. At the same time, a limit sensor 15 and a corrosion liquid concentration sensor 16 are installed to monitor the liquid level and concentration of the corrosion liquid 9 at the arch foot in the corrosion tank 2 in real time, and a salt spray concentration sensor 17 is installed to monitor the salt spray concentration at the arch top in the corrosion tank 2 in real time.

[0082] S6: Record and analyze the stress, strain, deformation, corrosion degree and damage evolution of the structure during the test.

[0083] The test device described in the present invention can carry out arch salt spray corrosion + arch foot dry-wet cycle corrosion tests, which can apply spray corrosion (simulating dry-wet cycle corrosion in the splash zone) to the arch foot area of ​​the steel tube concrete arch rib 1 while applying salt spray corrosion (simulating marine atmospheric corrosion or industrial atmospheric corrosion) to the arch area, truly simulating the impact of corrosion on the arch rib structure of a long-span arch bridge in coastal areas.

[0084] Special note, this implementation plan and attached Figure 1 、 6 The structure shown in Figure 9 is merely one proposed test setup, using a single-limb square-section concrete arch rib specimen 1 as an example. However, the present invention is not limited to this specific structure and operating process. The cross-sectional shape of the arch rib specimen 1, the configuration of the corrosion groove 2, and the loading method can be adjusted to suit different test conditions based on actual test requirements.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An intelligent test device for long-term load and corrosion of steel tube concrete arch rib components, characterized in that: include: A corrosion groove (2) is coated on the outside of the steel tube concrete arch rib specimen (1), and the corrosion groove (2) can be filled with or sprayed with a corrosion liquid (9); During the filling or spraying of the corrosive liquid (9), a limit sensor (15) and a corrosive liquid concentration sensor (16) are used to intelligently monitor the test. The limit sensor (15) and the corrosive liquid concentration sensor (16) are connected to a data acquisition terminal (18) via an external wire to monitor the liquid level and concentration of the corrosive liquid (9) in the corrosion tank (2) in real time, and the test is monitored and regulated by an on-site or remote computer device. A load applying device comprising a plurality of load applying units, each of the load applying units being used to apply a long-term load to the steel tube concrete arch rib specimen (1); Each of the load applying units comprises a screw (3), a nut (4), a loading end plate (6), a loading block (7), and a force transmission block (8); The first end of the loading block (7) is fixed to the loading end plate (6), and the second end of the loading block (7) passes through the corrosion groove (2) and is tightly fitted with the steel tube concrete arch rib specimen (1); The first end of the force transmission block (8) is fixed to the loading end plate (6), and the second end of the force transmission block (8) is located below the loading block (7) and is tightly fitted with the corrosion groove (2); A plurality of screw rods (3) are arranged to penetrate the corrosion groove (2), and both ends of the screw rods (3) are fixedly mounted on the loading end plate (6) via the nuts (4), so that the loading block (7) can exert force on the steel tube concrete arch rib specimen (1).

2. The intelligent test device for long-term load and corrosion of steel tube concrete arch rib components according to claim 1 is characterized in that: The cross-sectional shape of the corrosion groove (2) is consistent with the cross-sectional shape of the steel tube concrete arch rib specimen (1).

3. The intelligent test device for long-term load and corrosion of steel tube concrete arch rib components according to claim 2 is characterized in that: The corrosion tank (2) can be used as a cathode plate, the inner surface of the corrosion tank (2) is connected to the cathode of an external DC power supply (10), and the steel tube concrete arch rib specimen (1) is connected to the anode of the external DC power supply (10).

4. The intelligent test device for long-term load and corrosion of steel tube concrete arch rib components according to claim 1 is characterized in that: The top of the corrosion groove (2) symmetrically forms two inclined surfaces.

5. The intelligent test device for long-term load and corrosion of steel tube concrete arch rib members according to claim 4 is characterized in that: The corrosion tank (2) comprises a salt spray nozzle (201) and a spray head (202), wherein the salt spray nozzle (201) is arranged close to the arch top of the steel tube concrete arch rib specimen (1), and the spray angle of the salt spray nozzle (201) is arranged to be inclined upward, and the spray head (202) is arranged close to the arch foot of the steel tube concrete arch rib specimen (1) for spraying the corrosion liquid (9) on the arch foot of the steel tube concrete arch rib specimen (1); The limit sensor (15) and the corrosive liquid concentration sensor (16) are arranged at the inner arch foot of the corrosion tank (2), and respectively monitor the liquid level and concentration of the corrosive liquid (9) at the inner arch foot of the corrosion tank (2) in real time; a salt mist concentration sensor (17) is also arranged at the inner arch top of the corrosion tank (2), and the salt mist concentration sensor (17) is connected to the data acquisition terminal (18) through an external wire to monitor the salt mist concentration at the inner arch top of the corrosion tank (2) in real time.

6. The intelligent test device for long-term load and corrosion of steel tube concrete arch rib components according to claim 5 is characterized in that: The corrosion trough (2) further comprises a drain outlet (203), a water inlet pipe (204) and a drain pipe (205); the salt spray nozzle (201) and the spray head (202) are connected to the water storage device (11) via the water inlet pipe (204); the drain outlet (203) is connected to the water storage device (11) via the drain pipe (205); and the drain outlet (203) is arranged at the bottom of the corrosion trough (2).

7. The intelligent test device for long-term load and corrosion of steel tube concrete arch rib members according to claim 1 is characterized in that: The number of the screw rods (3) is 2, 4, 6, 8, 10 or 12, and the screw rods (3) are evenly distributed on the periphery of the loading block (7).

8. The intelligent testing device for long-term load and corrosion of concrete-filled steel tube arch rib members according to any one of claims 1 to 7, characterized in that: Each load applying unit further comprises a compressive load sensor (14), wherein the compressive load sensor (14) is used to measure the magnitude of the compressive load applied by the load applying unit.

9. An intelligent test method for long-term load and corrosion of steel tube concrete arch rib components, characterized in that: The long-term load and corrosion intelligent testing device for steel tube concrete arch rib members according to any one of claims 1 to 8 is used, comprising the following steps: S1: Install and fix the steel tube concrete arch rib specimen (1); S2: Wrap the corrosion groove (2) on the outside of the steel tube concrete arch rib specimen (1); S3: Pass the loading block (7) through the corrosion groove (2) and fit it tightly with the steel tube concrete arch rib specimen (1); set the force transmission block (8) below the loading block (7) and fit it tightly with the corrosion groove (2); pass the screw (3) through the corrosion groove (2) and fix it to the loading end plate (6) through the nut (4), so that the loading block (7) can apply force to the steel tube concrete arch rib specimen (1); S4: sealing the corrosion groove (2); S5: pouring the corrosion liquid (9) into the corrosion tank (2), using the corrosion tank (2) as a cathode plate, connecting the inner surface of the corrosion tank (2) to the cathode of the external DC power supply (10), connecting the steel tube concrete arch rib specimen (1) to the anode of the external DC power supply (10), and carrying out an electrochemical accelerated corrosion test. At the same time, installing a limit sensor (15) and a corrosion liquid concentration sensor (16) to monitor the liquid level and concentration of the corrosion liquid (9) in real time; Alternatively, a salt spray nozzle (201) is provided at the arch top near the steel tube concrete arch rib specimen (1), the spray angle of the salt spray nozzle (201) is provided to be inclined upward, a spray head (202) is provided at the arch foot near the steel tube concrete arch rib specimen (1), the arch top is subjected to salt spray corrosion by the salt spray nozzle (201), and the arch foot is subjected to dry-wet cycle corrosion by the spray head (202), and a limit sensor (15) and a corrosion liquid concentration sensor (16) are installed to monitor the liquid level and concentration of the corrosion liquid (9) at the arch foot in the corrosion tank (2) in real time, and a salt spray concentration sensor (17) is installed to monitor the salt spray concentration at the arch top in the corrosion tank (2) in real time; S6: Record and analyze the stress, strain, deformation, corrosion degree and damage evolution of the structure during the test.

10. The intelligent test method for long-term load and corrosion of concrete-filled steel tube arch rib members according to claim 9, characterized in that: In the S3, the load size is adjusted by tightening the nut (4) to simulate different load effects.

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