Device and method for testing mechanical properties of structure under coupling action of multiple working conditions

Abstract

The invention relates to the field of test of mechanical properties of a concrete-filled steel tube structure, in particular to a device and a method for testing the mechanical properties of the structure under a multi-working-condition coupling effect, and the device comprises a test piece end plate for fixing a test piece; the bending test device is used for applying pressure from the upper end and the lower end; the corrosion test device is used for carrying out a corrosion test; the irradiation test device is used for carrying out an ultraviolet irradiation test; the measuring device is used for measuring mechanical properties of the test piece. According to the test device, long-term bending load, ultraviolet radiation and corrosion effects are introduced at the same time, so that the blank of a structural mechanical property test device under the multi-working-condition coupling effect of long-term bending load, ultraviolet radiation and corrosion of the concrete filled steel tube is filled up; the device can realize coexistence of soaking and dry-wet cycle multi-type corrosion effects and regional non-uniform corrosion and non-uniform ultraviolet radiation effects, and can realize a bending ultimate bearing capacity test of the concrete filled steel tube on the premise that a long-term bending load is not unloaded.

Description

Technical Field

[0001] The present invention relates to the field of mechanical performance testing of steel tube concrete structures, and in particular to a structural mechanical performance testing device and a testing method under multi-working condition coupling. Background Art

[0002] Concrete-filled steel tube (CFST) structures are a composite structure consisting of an outer steel tube and infill concrete. They possess superior mechanical properties such as high bearing capacity, good ductility, and strong disaster resistance, and are widely used in engineering fields such as high-rise buildings, long-span bridges, and transmission towers. CFST structures are subjected to long-term loads during their service, which causes significant shrinkage and creep of the core concrete, thereby weakening the restraining effect of the steel tube on the concrete, causing internal force redistribution between the steel tube and concrete, and reducing the bearing capacity of the CFST structure. Due to multiple factors, including special design, load location and direction, and the asymmetry of the structural geometry, CFST structures are typically subject to compressive bending loads in actual engineering. The long-term effects of compressive bending loads exacerbate the complexity of the structural stress performance, posing a significant threat to its bearing performance and safety.

[0003] In addition, for practical projects such as large-span steel tube concrete bridges and transmission towers at sea and along the coast, their structures are exposed to strong ultraviolet radiation and highly corrosive environments for a long time. For example, in my country's southeastern coastal areas, which have high visibility, high temperatures, and low total cloud cover, the daily extreme ultraviolet radiation values ​​are usually at least 3 to 11 W / m higher than those in inland areas. 2 The total annual solar radiation in the South China Sea is close to 7000MJ / m 2 This is one of the main reasons for the deterioration of the mechanical properties of local engineering structural materials. Strong ultraviolet radiation has a significant accelerating effect on the deterioration of the mechanical properties of concrete and metal materials. Long-term exposure to strong ultraviolet radiation can cause serious aging and damage to the entire structure.

[0004] At the same time, substances like chloride ions, sulfates, and carbon dioxide in seawater and other environments can easily catalyze and destroy the passive film on the surface of steel pipes, leading to corrosion. Especially in splash zones and tidal areas near sea level, where the wet-dry cycle caused by waves and tides makes it more likely that the anti-corrosion coatings on the surface of offshore structures will age and fall off, and the concrete cover is also more susceptible to chloride ion penetration, losing its protective effect. Therefore, the impact of various types of corrosion in these seawater and other environments on the safe service life of steel pipe concrete structures cannot be ignored.

[0005] In summary, the main steel-concrete-filled (CFST) structures of long-span bridges and transmission towers in offshore and coastal areas, particularly those in southeastern my country's highly UV-exposed coastal regions, are subject to the coupled effects of long-term compressive and bending loads, UV radiation, and corrosion during their service. To clarify the working mechanism and overall stress-bearing process of CFST structures under the combined influence of these three factors, and to provide a technical basis for their safe service, a reasonable and feasible test setup is urgently needed to study their mechanical properties.

[0006] If a test study under the coupled effects of "long-term compression and bending load + UV irradiation + corrosion" is required, the usual test method is to use a long-term load loading device to apply a long-term load to the specimen, then place the specimen with the long-term load in a UV irradiation chamber for UV irradiation testing, and then place the specimen after the above test in a corrosion tank for corrosion testing. The above test method has the following inconveniences: First, the existing long-term load loading devices are mainly used to realize long-term "axial compression" load effects, and it is difficult to realize long-term "compression bending" load effects and the coupling effects of long-term compression bending loads with other working conditions; although individual test devices can realize the coupling effects of long-term loads and working conditions such as corrosion, in their coupling test, the simulation method of working conditions such as corrosion is single, and the environmental working conditions that can be reflected are relatively limited, and the components of the long-term load device are easily "directly" affected by corrosion and other effects and damaged prematurely; if test equipment (devices) such as jacks and self-reaction frames are used for long-term "compression bending" load loading, there will be problems such as long-term occupancy of the test equipment (device), cumbersome operation procedures for long-term load supplementation (long-term load supplementation is required due to stress relaxation), and it is not convenient for batch loading of specimens.

[0007] Secondly, when the specimen under long-term compression and bending load is placed as a whole in a UV irradiation box for UV irradiation test, under the action of UV irradiation, the components of the long-term compression and bending load loading device are susceptible to high temperature and UV aging, which shortens the service life or even fails, thereby greatly affecting the accuracy of the test data under long-term load. Although corresponding protection measures can be taken for key components, it is difficult to maintain the stability of the long-term load during the test. Moreover, it is difficult to perform long-term load supplementary loading operations during the UV irradiation test.

[0008] Third, it is difficult for existing corrosion test equipment to simulate the simultaneous corrosion of offshore steel tube concrete structures under multiple working conditions, such as the combined effects of "seawater immersion corrosion (occurring in the lower part of the structure) and dry-wet cycle corrosion caused by waves and tides (occurring in the upper part of the structure)", which deviates from the actual service conditions of offshore steel tube concrete structures.

[0009] Fourth, when conducting experimental research on steel tube concrete components and their connection nodes under corrosion (or ultraviolet radiation), the specimens are placed in a corrosion tank (or ultraviolet radiation box) test device. The corrosion concentration (or ultraviolet radiation intensity) inside the test device is usually consistent, making it difficult to achieve uneven corrosion (or uneven ultraviolet radiation) in different areas of steel tube concrete components and steel tube concrete connection nodes, and unable to meet the actual working conditions of the project.

[0010] Fifth, when conducting a "compression-bending" ultimate bearing capacity loading test on a specimen after the long-term "compression-bending" load is coupled with other working conditions, it is difficult for the existing device to meet the requirement that the specimen is not unloaded (i.e., deformation does not rebound) after the long-term compression-bending load and to conduct compression-bending ultimate bearing capacity loading, which makes the provided test conditions different from the actual engineering conditions.

[0011] In summary, the currently available mechanical properties testing equipment for steel tube concrete structures cannot realize the combined effects of "long-term compression and bending loads + ultraviolet radiation + corrosion", and cannot effectively simulate the mechanical properties degradation characteristics of steel tube concrete structures under the combined effects of long-term compression and bending loads, ultraviolet radiation and corrosion. It has limitations in revealing the degradation mechanism of structural bearing performance and cannot fully reflect the impact of complex environments on the safe bearing capacity of the overall structure. Summary of the Invention

[0012] The purpose of the present invention is to make up for the deficiency of the existing steel tube concrete structure mechanical performance test device that cannot truly reflect the impact of complex environment on the safe bearing of the overall structure, and to provide a structural mechanical performance test device and test method under multi-working condition coupling.

[0013] In a first aspect, the present invention provides a structural mechanical properties testing device under the coupling action of multiple working conditions, which can simultaneously realize the coupling action of long-term compression and bending load, ultraviolet irradiation and corrosion on steel tube concrete specimens, comprising: two specimen end plates, the specimen end plates comprising a plate body, a loading block being provided on one side of the plate body, the loading block being used to transmit eccentric pressure to the specimen, and the plate body being used to fix the specimen; a compression and bending test device, the compression and bending test device being connected to the loading block, the compression and bending test device being used to apply pressure to the specimen from the upper and lower ends; a corrosion test device, the corrosion test device comprising a corrosion groove, the corrosion groove enclosing the specimen, the corrosion test device being used to perform a corrosion test on the specimen; an irradiation test device, the irradiation test device being installed on the side of the corrosion groove facing the specimen, the irradiation test device being used to perform an ultraviolet irradiation test on the specimen; a measuring device, the measuring device being used to measure the mechanical properties of the specimen under the action of at least one of the compression and bending test device, the corrosion test device and the irradiation test device.

[0014] The structural mechanical performance test device under multi-working condition coupling provided by the present invention is equipped with a compression and bending test device, a corrosion test device, and an irradiation test device. It can simultaneously introduce the triple effects of long-term compression and bending loads, ultraviolet irradiation, and corrosion. By being compatible with multiple corrosion methods, it can realistically simulate the service environment of marine engineering facilities and meet the needs of various types of tests. The test device achieves precise transmission of eccentric pressure through the loading block, which can simulate the combined compression and bending stress state caused by factors such as load asymmetry and structural geometry asymmetry in actual engineering, greatly improving the simulation degree of the test simulation of actual engineering conditions. For the strong ultraviolet radiation environment under some special working conditions, a special irradiation test device is designed, which can well simulate the changes in the mechanical properties of the structure exposed to strong ultraviolet radiation environment for a long time. Through the design of the corrosion groove enclosing the specimen, it can simulate the test conditions of spraying dry-wet cycle in the splash zone, immersion dry-wet cycle in the tidal zone, coexistence of multiple types of corrosion effects such as immersion and dry-wet cycle, or other corrosive environments. The specimen is subjected to uniform corrosion or only to regional non-uniform corrosion tests on its designated areas, accurately reflecting the corrosion process of corrosive substances such as chloride ions and sulfates on steel tube concrete structures. The structural mechanical properties testing device under multi-working condition coupling provided by the present invention realizes long-term compression and bending load research on specimens based on the principle of self-reaction force. It is small in size, easy to move and disassemble, occupies a small area and has low requirements for the test site. It can be recycled multiple times and has significant economic advantages. The testing device can carry out mechanical property testing research of steel tube concrete under the coupling influence of long-term compression and bending load + ultraviolet radiation + corrosion, filling the gap in long-term compression and bending load + ultraviolet radiation + corrosion testing devices in the field of steel tube concrete research. The testing device is equipped with a special measuring device, which can monitor the mechanical properties of the specimen under various composite effects in real time, making it convenient to draw the load-tension / compression deformation stress curve of the long-term compression and bending member of the steel tube concrete in the later stage, providing accurate data support for studying the degradation mechanism and degradation process of the steel tube concrete structure.

[0015] Preferably, the bending test device includes two oppositely arranged bearing plates, which are connected to the pull rod through nuts. The nuts are used to adjust the bearing plates to move closer to or farther away from each other under the guidance of the pull rod. Knife-edge hinges are provided on the opposite surfaces of the two bearing plates, and the knife-edge hinges are concavely matched with the loading block.

[0016] The combined design of nuts and pull rods enables the device to adapt to specimens of different sizes and specifications. The nuts can be used to control the distance between the two bearing plates, thereby achieving precise adjustment of the pressure applied to the specimen, and facilitating the simulation of the stress state of steel tube concrete structures under different load levels. The two bearing plates form a self-reaction force system through the pull rods, enabling the device to achieve continuous compression and bending loading of the specimen without relying on external large-scale loading equipment. The concave and convex matching design of the knife-edge hinge and the loading block ensures a stable connection during the loading process. The pressure applied by the bearing plate is accurately transmitted to the loading block through the knife-edge hinge. The loading block is eccentrically set relative to the specimen, thereby accurately simulating the complex stress state of steel tube concrete structures caused by load or geometric asymmetry in actual engineering.

[0017] Preferably, the corrosion test device further comprises a water tank device, which is connected to the corrosion tank via a water inlet pipe and a water outlet pipe, and is used to transport the corrosive liquid to the corrosion tank.

[0018] The water tank device is connected to the corrosion tank through the water inlet pipe and the water outlet pipe, which can realize the periodic delivery and discharge of the corrosive liquid, such as a 12-hour drying and 12-hour immersion cycle, accurately simulating the high tide and low tide process in the ocean tidal zone. It can truly reflect the dry-wet cycle corrosion effect of marine engineering structures immersed in the seawater tidal zone and dried under high humidity, providing real conditions for studying the corrosion characteristics of steel tube concrete in this environment and improving the accuracy of the test.

[0019] Preferably, the corrosion testing device also includes a water tank device, and a plurality of spray heads are set on the inner wall of the corrosion tank. The water tank device is connected to the spray heads through a water inlet pipe, and the water tank device is also connected to the corrosion tank through a water outlet pipe. The water tank device is used to transport corrosive liquid to the corrosion tank.

[0020] By setting up several spray heads on the inner wall of the corrosion tank, the specimens are placed in an environment of alternating spraying and air drying, such as a 12-hour drying and 12-hour spraying cycle. This can simulate the splash and atomization characteristics of seawater in the ocean splash zone and improve the test accuracy.

[0021] Preferably, the corrosion test device further includes a DC power supply and a cathode plate, wherein the cathode plate is located in the corrosion tank, the cathode of the DC power supply is electrically connected to the cathode plate, and the anode of the DC power supply can be electrically connected to the test piece.

[0022] By establishing an electrochemical corrosion environment through a DC power supply, using the specimen as the anode and the cathode plate as the cathode to form an electrochemical corrosion circuit, the corrosion process of the steel tube concrete structure can be significantly accelerated, and the corrosion process that may take several years or even decades in the natural environment can be compressed into a time range acceptable to the laboratory.

[0023] Preferably, the irradiation test device comprises a fluorescent ultraviolet lamp tube, and the electromagnetic wave wavelength of the fluorescent ultraviolet lamp tube is ≥250nm.

[0024] The preferred irradiation test device is a fluorescent ultraviolet lamp with an electromagnetic wave wavelength of 250nm or more. The radiation from the lamp can better penetrate the corrosive liquid, reduce the refraction and attenuation of the ultraviolet light by the corrosive liquid, and ensure that the ultraviolet radiation can still effectively act on the surface of the specimen even in the presence of the corrosive liquid. In addition, the ultraviolet light with an electromagnetic wave wavelength of 250nm or more is consistent with the wavelength range of ultraviolet light reaching the surface in natural sunlight (the surface ultraviolet light is mainly UV-A and some UV-B, with a wavelength range of approximately 280-400nm), which can more accurately simulate the ultraviolet radiation conditions to which the steel tube concrete structure is exposed in the actual environment, thereby improving the accuracy of the test.

[0025] The irradiation intensity of the fluorescent ultraviolet lamp at different positions is adjusted according to test requirements, so that a uniform ultraviolet irradiation test or a zone-by-zone non-uniform ultraviolet irradiation test can be performed on the test piece.

[0026] Preferably, the measuring device includes a strain gauge, a micrometer and a compressive load sensor, the strain gauge is installed on the test piece, the micrometer is installed on the bearing plate, and the compressive load sensor is installed between the bearing plate and the nut.

[0027] By installing strain gauges on the specimen, the local strain on the specimen surface can be directly measured, accurately capturing the deformation characteristics and stress distribution state of steel tube concrete in complex environments. The micrometer is installed on the load-bearing plate, which can monitor the overall axial deformation and deflection changes of the test specimen in real time, providing macroscopic deformation data that complements the local data of the strain gauge. The compressive load sensor is installed between the load-bearing plate and the nut, which can accurately measure the actual pressure applied to the specimen, ensuring precise control of the test conditions and data recording. The combined use of the three measuring devices forms a complete mechanical property monitoring system that can simultaneously obtain load, strain and displacement data, and comprehensively reflect the mechanical response process of the specimen.

[0028] Preferably, the spray head is arranged at the upper part of the corrosion tank. By controlling the switch of the spray head, the predetermined area at the lower part of the specimen is placed in an immersion environment, and the predetermined area at the upper part of the specimen is placed in a spraying environment or a dry-wet cycle environment, thereby realizing the coexistence of multiple types of corrosion effects of immersion and dry-wet cycle.

[0029] Preferably, when conducting a corrosion test on a steel tube concrete connection node or a predetermined area of ​​steel tube concrete, the spray head is controlled to spray the steel tube concrete connection node or the predetermined area of ​​steel tube concrete, so that the corrosion test is only carried out on a specific area of ​​the specimen, so that different parts of the specimen are subjected to regionally uneven corrosion.

[0030] Preferably, the type and ratio of the corrosive liquid are adjustable. By using corrosive liquids of different types and ratios, simulation of corrosive environments under more working conditions such as offshore, deep sea, salt lake, corrosive groundwater, etc. can be achieved.

[0031] In a second aspect, the present invention provides a method for testing the mechanical properties of a structure under multi-working condition coupling, using the above-mentioned test device for the mechanical properties of a structure under multi-working condition coupling, comprising the following steps: S1: Weld both ends of the specimen to the plate, and set the loading block eccentrically relative to the specimen; use a corrosion trough to surround the specimen, and the corrosion trough is detachably connected to the compression bending test device; S2: Use a bending test device to conduct a long-term bending load test on the specimen, use a corrosion test device to conduct a corrosion test on the specimen, and use an irradiation test device to conduct an ultraviolet irradiation test on the specimen, and monitor the information of the measuring device in real time; S3: Complete bending test, corrosion test, and UV irradiation test.

[0032] The method for testing the mechanical properties of structures under the coupling of multiple working conditions provided by the present invention can simultaneously perform compression and bending tests, corrosion tests, and ultraviolet irradiation tests, successfully realizing the simulation of the coupling effects of three environmental factors, filling the gap in test methods in this field. By eccentrically setting the loading block relative to the specimen, the method accurately simulates the compression and bending composite stress state caused by factors such as load asymmetry and structural geometric asymmetry in actual engineering, thereby improving the authenticity of the test simulation of actual engineering conditions.

[0033] Preferably, in S2, a corrosion test device is used to conduct a corrosion test on the specimen, including at least one of an immersion dry-wet cycle corrosion test in a tidal zone, a spray dry-wet cycle corrosion test in a splash zone, an electrochemical accelerated corrosion test, and a test of multiple types of corrosion effects coexisting with immersion and dry-wet cycles; When conducting the tidal zone immersion dry-wet cycle corrosion test, the corrosion test device includes a water tank device, which is connected to the corrosion tank through a water inlet pipe and a water outlet pipe. The water tank device is used to transport the corrosion liquid to the corrosion tank; the corrosion liquid in the corrosion tank is regularly filled or emptied to keep the test piece in an environment of alternating immersion and air drying; When conducting the splash zone spray dry-wet cycle corrosion test, the corrosion test device includes a water tank device, and a plurality of spray heads are set on the inner wall of the corrosion tank. The water tank device is connected to the spray heads through a water inlet pipe, and the water tank device is connected to the corrosion tank through a water outlet pipe. The water tank device transports the corrosive liquid to the corrosion tank; the spray heads are used to spray the corrosive liquid on the surface of the specimen at regular intervals, so that the specimen is in an environment where the spraying and air-drying phases alternate; When conducting an electrochemical accelerated corrosion test, the corrosion test apparatus includes a DC power supply and a cathode plate. The cathode plate is located in a corrosion tank. The cathode of the DC power supply is electrically connected to the cathode plate, and the anode of the DC power supply is electrically connected to the test piece. After the corrosion solution is poured into the corrosion tank, the electrochemical accelerated corrosion test is started. When conducting a test involving the coexistence of multiple types of corrosion actions, including immersion and dry-wet cycle, the corrosion test device includes a water tank device, and a number of sprinkler heads are arranged on the inner wall of the corrosion tank. The water tank device is connected to the sprinkler head through a water inlet pipe, and the water tank device is connected to the corrosion tank through a water outlet pipe, so that the predetermined area below the specimen is in an immersion environment, and the predetermined area above the specimen is in a sprinkler environment or a dry-wet cycle environment.

[0034] Different engineering structures face different corrosion environments. This design can specifically select the corrosion test method that is closest to the actual environment. It provides four different test methods: immersion dry-wet cycle corrosion test in tidal zone, spray dry-wet cycle corrosion test in splash zone, electrochemical accelerated corrosion test, and immersion and dry-wet cycle multi-type corrosion coexistence test. In addition, the corrosion test device can also use different types and proportions of corrosive liquids to simulate the corrosion environment under more working conditions such as nearshore, deep sea, salt lake, corrosive groundwater, etc., and comprehensively simulate the corrosion process of steel tube concrete structures under various corrosive water environment conditions, greatly improving the applicability of the test.

[0035] Preferably, the bending test device includes two oppositely arranged bearing plates, the bearing plates are connected to the pull rods through nuts, and the nuts are used to adjust the bearing plates to move closer to or farther away from each other under the guidance of the pull rods; and further includes the following steps: S4: Keep the bending test device intact, remove the corrosion test device, place the bending test device in the pressure testing machine, and fix the bearing plates to the loading plates of the pressure testing machine; S5: After initially loading the specimen using a pressure testing machine to a value exceeding the designed long-term load value, remove the nuts and tie rods and continue loading the specimen using the pressure testing machine until the specimen fails.

[0036] In traditional testing methods, after long-term compression and bending loads, before conducting the ultimate bearing capacity failure test of the steel tube concrete structure, it is usually necessary to unload the structure after the long-term load test is completed, remove the long-term device (i.e., remove the long-term load on the steel tube concrete structure), and then reload the steel tube concrete structure to failure. This causes the deformation of the steel tube concrete structure under long-term loads to rebound before the ultimate bearing capacity loading is performed, resulting in large test errors. The structural mechanical performance testing method under multi-working condition coupling provided by the present invention should first remove the corrosion test device, nuts, tie rods, and other devices that may interfere with the compression and bending ultimate bearing capacity test before conducting the compression and bending ultimate bearing capacity test. The compression and bending ultimate bearing capacity test can be directly performed while keeping the compression and bending test device unloaded, thereby clarifying the full-life working mechanism of steel tube concrete structures in offshore and coastal areas under long-term compression and bending loads until final failure.

[0037] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a structural mechanical performance testing device under multiple coupled working conditions. It includes a compression and bending test device, a corrosion test device, and an irradiation test device. This device can simultaneously introduce the triple effects of long-term compression and bending loads, ultraviolet radiation, and corrosion. By being compatible with multiple corrosion methods, it can realistically simulate the service environment of offshore facilities and meet the needs of various types of tests. 2. The present invention provides a test device for the mechanical properties of structures under the action of multiple coupled working conditions. By accurately transmitting eccentric pressure through a loading block, the device can simulate the combined compression and bending stress state caused by factors such as load asymmetry and structural geometric shape asymmetry in actual engineering, greatly improving the simulation degree of the test to the actual engineering conditions. For some special working conditions with strong ultraviolet radiation, a special irradiation test device is designed to effectively simulate the changes in the mechanical properties of structures exposed to strong ultraviolet radiation for a long time. By designing the test piece surrounded by corrosion grooves, the device can simulate test conditions such as spray dry-wet cycles in the splash zone, immersion dry-wet cycles in the tidal zone, the coexistence of multiple types of corrosion effects such as immersion and dry-wet cycles, or other corrosive environments. It can also conduct regional non-uniform corrosion tests on the test piece, either uniformly corroding the test piece or corroding only designated areas, accurately reflecting the corrosion process of corrosive substances such as chloride ions and sulfates on steel tube concrete structures. 3. The present invention provides a testing device for the mechanical properties of structures under multiple coupled working conditions. Based on the principle of self-reaction force, this device is compact, easy to move and disassemble, occupies a small area, and requires a low test site. It can be reused multiple times, offering significant economic advantages. This testing device is capable of conducting tests on the mechanical properties of concrete-filled steel tubes (CFSTs) under the coupled effects of long-term compressive bending loads, ultraviolet radiation, and corrosion, filling a gap in the field of CFST research for testing long-term compressive bending loads, ultraviolet radiation, and corrosion. Equipped with specialized measuring devices, this testing device enables real-time monitoring of the mechanical properties of specimens under various combined effects, facilitating the subsequent drawing of load-tension / compression deformation curves for CFSTs under long-term compressive bending conditions, providing accurate data support for studying the degradation mechanisms and processes of CFST structures. 4. This invention provides a method for testing the mechanical properties of structures under multiple coupled working conditions. This method allows for targeted selection of the corrosion test method that most closely resembles the actual environment. By providing four different test methods—immersion-dry-wet cyclic corrosion testing in the tidal zone, spray-dry-wet cyclic corrosion testing in the splash zone, electrochemical accelerated corrosion testing, and a test involving simultaneous immersion and dry-wet cyclic corrosion—and by employing different types and proportions of corrosive fluids in the corrosion test apparatus, this method comprehensively simulates the corrosion process of concrete-filled steel tube structures under various corrosive water environments, significantly expanding the test's applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the connection between the circular concrete-filled steel tube specimen and the specimen end plate; Figure 2 for Figure 1 Side view; Figure 3 for Figure 1 Top view; Figure 4 for Figure 1 Bottom view; Figure 5 Schematic diagram of the connection between the square concrete-filled steel tube specimen and the specimen end plate; Figure 6 for Figure 5 Top view; Figure 7 Schematic diagram of the connection between the steel tube concrete truss hybrid structure specimen and the specimen end plate; Figure 8 for Figure 7 Top view; Figure 9 Schematic diagram of the connection between the steel tube concrete T-shaped node specimen and the specimen end plate; Figure 10 for Figure 9 Top view; Figure 11Schematic diagram of the bending test device structure; Figure 12 This is the plan view of the compression bending test device; Figure 13 Schematic diagram of the structure during long-term compression and bending load test; Figure 14 This is a schematic diagram of the plane when conducting long-term compression and bending load tests; Figure 15 This is a top view of the corrosion tank of the circular concrete-filled steel tube specimen after the irradiation test device was installed; Figure 16 This is a cross-sectional view of the corrosion tank of the circular concrete-filled steel tube specimen after the irradiation test device is installed; Figure 17 This is a top view of the corrosion groove of the steel tube concrete T-joint specimen after the irradiation test device was installed; Figure 18 This is a cross-sectional view of the corrosion groove of the concrete-filled steel tube T-node specimen after the irradiation test device was installed; Figure 19 Schematic diagram of the structure for conducting partial corrosion + UV irradiation test on concrete-filled steel tube T-joint specimens; Figure 20 Schematic diagram of the corrosion tank assembly before the corrosion test of the concrete-filled steel tube T-joint specimen; Figure 21 Schematic diagram of the structure for conducting long-term compression and bending load test + UV irradiation test + tidal zone immersion dry-wet cycle corrosion test; Figure 22 Schematic diagram of the plane when conducting long-term compression and bending load test + UV irradiation test + tidal zone immersion dry-wet cycle corrosion test; Figure 23 Schematic diagram of the structure for conducting long-term compression and bending load test + UV irradiation test + splash zone spray dry-wet cycle corrosion test; Figure 24 Schematic diagram of the plane when conducting long-term compression bending load test + UV irradiation test + splash zone spray dry-wet cycle corrosion test; Figure 25 Schematic diagram of the structure when conducting long-term compression bending load test + UV irradiation test + electrochemical accelerated corrosion test; Figure 26 Schematic diagram of the plane when conducting long-term compression bending load test + UV irradiation test + electrochemical accelerated corrosion test; Figure 27 This is a structural diagram of the compression bending ultimate bearing capacity test that is carried out directly without unloading after the long-term compression bending load test is completed; Figure 28 This is a plan view of the bending ultimate bearing capacity test that is carried out directly without unloading after the long-term bending load test is completed.

[0039] Markings in the figure: 1-specimen end plate, 11-plate body, 12-loading block, 13-stiffening rib, 2-compression-bending test device, 21-load-bearing plate, 22-nut, 23-pull rod, 24-knife-edge hinge, 31-corrosion groove, 311-sprinkler head, 32-water tank device, 321-water inlet pipe, 322-water outlet pipe, 33-DC power supply, 34-cathode plate, 35-drain outlet, 36-card slot, 4-irradiation test device, 51-strain gauge, 52-micrometer, 53-compression load sensor, 6-pressure testing machine, 100-specimen. DETAILED DESCRIPTION

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] In addition, in the description of the embodiments of the present invention, "several," "plurality," and "a number" represent at least two. The number may be any number such as two, three, four, five, six, seven, eight, nine, or even more than nine.

[0045] 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.

[0046] Example 1 The present embodiment provides a device for testing the mechanical properties of a structure under a multi-working condition coupling effect, which can simultaneously introduce the triple effects of long-term compression and bending loads (long-term loads are relative to short-term loads. In actual tests, short-term loads are generally loaded for several hours to several days, while long-term loads are loaded for several months or longer, such as one month, two months or longer), ultraviolet radiation, and corrosion. The device for testing the mechanical properties of a structure under a multi-working condition coupling effect (i.e., the coupling effect of "long-term compression and bending loads + ultraviolet radiation + corrosion") provided in the present embodiment can simultaneously achieve the coupling effects of long-term compression and bending loads, ultraviolet radiation, and corrosion on a steel tube concrete specimen 100, and includes: two specimen end plates 1, for example Figures 1 to 10 As shown (for easy observation Figures 1 to 10 Only the case where the specimen end plate 1 is set on one side of the specimen 100 is shown). The upper and lower ends of the specimen 100 can be fixedly connected to the specimen end plate 1.

[0047] The specimen end plate 1 includes a plate body 11, and a loading block 12 is provided on one side of the plate body 11, for example Figure 1 As shown, the loading block 12 can be arranged on the side of the plate 11 away from the specimen 100. The loading block 12 is used to transmit eccentric pressure to the specimen 100, for example Figures 1 to 4 As shown, the loading block 12 is eccentrically arranged relative to the specimen 100 . Specifically, the loading block 12 may be a bar-shaped block with a groove on one side facing away from the plate body 11 .

[0048] The plate 11 is used to fix the test piece 100, specifically, for example Figures 1 to 4The figure shows a circular concrete-filled steel tube specimen 100, whose outer steel tube has a circular cross-section, connected to a plate 11. It is understood that the cross-section of the outer steel tube can be a standard circle, an ellipse, or other special circular shapes. The outer steel tube should be welded to the plate 11. Furthermore, for compression bending testing, stiffening ribs 13 can be welded between the outer steel tube and the plate 11. The stiffening ribs 13 can be evenly distributed throughout the circular cross-section of the outer steel tube.

[0049] For example Figure 5~Figure 6 The figure shows the connection between a square steel tube concrete test specimen 100 with a square outer steel tube and a plate 11. It is understood that the cross section of the outer steel tube can be a polygon, such as a square, rectangle, regular hexagon, regular octagon, or other standard or non-standard polygonal steel tubes. The outer steel tube should be welded to the plate 11. At the same time, for the purpose of compression bending test, stiffening ribs 13 can also be welded between the outer steel tube and the plate 11, as shown in FIG. Figure 6 As shown, the stiffening ribs 13 can be welded to the four sides of the square concrete-filled steel tube specimen 100 .

[0050] For example Figure 7-Figure 8 The figure shows the connection between the steel tube concrete truss hybrid structure specimen 100 and the plate body 11. Figures 9 and 10 The figure shows the connection between the steel tube concrete T-joint specimen 100 and the plate 11. It is understood that the specimen 100 can also be other special-shaped steel tube concrete composite structures, such as steel tube concrete-joint structure, steel tube-shaped steel concrete structure, steel tube concrete truss hybrid structure, steel tube concrete reinforced hybrid structure, hollow sandwich steel tube concrete structure, and other types of steel tube concrete derivative structures. The structural type of the specimen 100 is mainly selected based on the actual engineering and architectural design form being studied.

[0051] The bending test device 2 is connected to the loading block 12 and is used to apply pressure to the test piece 100 from the upper and lower ends.

[0052] Furthermore, the bending test device 2 includes two oppositely arranged bearing plates 21, and the bearing plates 21 are connected to the pull rods 23 through nuts 22. Specifically, for example Figures 11 to 14 As shown, holes can be opened at the four corners of the support plate 21 for the rods 23 to pass through. After the rods 23 pass through the support plate 21, nuts 22 are tightened, and the nuts 22 and the rods 23 are threadedly connected. The nuts 22 are used to adjust the support plates 21 to move closer to or farther from each other under the guidance of the rods 23. Specifically, after the specimen 100 is placed between the two support plates 21 through the specimen end plate 1, the two support plates 21 can be tightened to move closer to each other, or loosened to move farther from each other.

[0053] The two opposite surfaces of the two supporting plates 21 are provided with knife-edge hinges 24, for example Figure 12As shown, the knife-edge hinge 24 installed on the upper supporting plate 21 faces downward, and the knife-edge hinge 24 installed on the lower supporting plate 21 faces upward, and the knife-edge hinge 24 is matched with the loading block 12 in a concave-convex manner.

[0054] The combined design of the nut 22 and the tie rod 23 enables the structural mechanical properties test device under the multi-working condition coupling of "long-term compression and bending load + ultraviolet radiation + corrosion" provided in this embodiment to adapt to specimens 100 of different sizes and specifications. The distance between the two bearing plates 21 can be controlled by the nut 22 to achieve precise adjustment of the pressure applied to the specimen 100, which is convenient for simulating the stress state of the steel tube concrete structure under different load levels. The two bearing plates 21 form a self-reaction force system through the tie rod 23, so that the device can achieve continuous compression and bending loading of the specimen 100 without relying on external large-scale loading equipment. The concave and convex matching design of the knife-edge hinge 24 and the loading block 12 ensures a stable connection during the loading process. The pressure applied by the bearing plate 21 is accurately transmitted to the loading block 12 through the knife-edge hinge 24. The loading block 12 is eccentrically set relative to the specimen 100, thereby accurately simulating the complex stress state of the steel tube concrete structure caused by load or geometric asymmetry in actual engineering.

[0055] The corrosion test device includes a corrosion tank 31, the corrosion tank 31 surrounds the test piece 100, and the corrosion test device is used to perform a corrosion test on the test piece 100. Specifically, Figures 15 to 20 As shown, the corrosion groove 31 can be designed as a symmetrical two-half split type, and the two halves of the corrosion groove 31 can be connected by a slot 36. The cross section of the corrosion groove 31 should be kept consistent with the cross section type of the specimen 100 as much as possible, for example Figure 15-16 As shown, when the cross section of the specimen 100 is circular, the corrosion groove 31 may be a circular cross section, for example Figures 17 to 20 As shown, when the specimen 100 is a T-shaped node, the corrosion groove 31 can be a T-shaped structure.

[0056] The irradiation test device 4 is installed on the side of the corrosion tank 31 facing the test piece 100 . The irradiation test device 4 is used to perform an ultraviolet irradiation test on the test piece 100 .

[0057] Specific example Figure 15-16 As shown, at this time, the cross section of the test piece 100 is circular, the corrosion groove 31 can be a cylindrical structure, and the irradiation test devices 4 are evenly distributed on the inner wall of the cylindrical corrosion groove 31.

[0058] Specific example Figure 17-18 As shown, at this time, the specimen 100 is a T-shaped node, and the corrosion groove 31 can be a T-shaped structure. Adaptively, the left half of the irradiation test device 4 can be set vertically, and the right half of the irradiation test device 4 can be set horizontally to match the shape of the T-shaped node specimen 100.

[0059] Further, such as Figures 19 and 20 As shown, according to the test requirements, the irradiation test device 4 can carry out a uniform irradiation test on the specimen 100, and can also be designed to carry out irradiation tests of different intensities on different areas of the specimen 100, that is, a regional non-uniform ultraviolet irradiation test, such as controlling the switches of the irradiation test devices 4 in different areas (each irradiation test device 4 is provided with an independent control circuit, thereby realizing independent control of each irradiation test device 4), thereby realizing a regional non-uniform ultraviolet irradiation test.

[0060] Furthermore, the irradiation test device 4 can be a fluorescent UV lamp, which can be bonded to the inner wall of the corrosion tank 31, and the electromagnetic wavelength of the fluorescent UV lamp is ≥250nm. Preferably, the irradiation test device 4 is a fluorescent UV lamp with an electromagnetic wavelength of ≥250nm. The radiation from the fluorescent UV lamp can better penetrate the corrosive liquid, reducing the refraction and attenuation of the ultraviolet light by the corrosive liquid, ensuring that the ultraviolet radiation can still effectively act on the surface of the test piece 100 even in the presence of the corrosive liquid. In addition, the ultraviolet radiation with a wavelength of ≥250nm is consistent with the wavelength range of ultraviolet radiation reaching the earth's surface in natural sunlight (the surface ultraviolet radiation is mainly UV-A and some UV-B, with a wavelength range of approximately 280nm to 400nm). Therefore, it can more accurately simulate the ultraviolet radiation conditions to which the steel tube concrete structure is exposed in an actual environment, thereby improving the accuracy of the test.

[0061] The measuring device is used to measure the mechanical properties of the test piece 100 under the action of the bending test device 2, and / or the corrosion test device, and / or the irradiation test device 4.

[0062] Furthermore, the measuring device includes a strain gauge 51, a micrometer 52, and a compressive load sensor 53. The strain gauge 51 can be installed on the specimen 100, the micrometer 52 can be installed on the top of the load plate 21, and the compressive load sensor 53 can be installed between the load plate 21 and the nut 22. By installing the strain gauge 51 on the specimen 100, the local strain on the surface of the specimen 100 can be directly measured, accurately capturing the deformation characteristics and stress distribution of the steel tube concrete under complex environments. The micrometer 52, installed on the load plate 21, can monitor the overall axial deformation and deflection changes of the specimen 100 in real time, providing macroscopic deformation data that complements the local data from the strain gauge 51. The compressive load sensor 53, installed between the load plate 21 and the nut 22, can accurately measure the actual pressure applied to the specimen 100, ensuring precise control of test conditions and data recording. The combination of these three measuring devices forms a complete mechanical property monitoring system that can simultaneously obtain load, strain, and displacement data, comprehensively reflecting the mechanical response of the specimen 100.

[0063] The structural mechanical performance test device under the multi-working condition coupling of "long-term compression and bending load + ultraviolet radiation + corrosion" provided in this embodiment is equipped with a compression and bending test device 2, a corrosion test device and an irradiation test device 4. It can simultaneously introduce the triple effects of long-term compression and bending load, ultraviolet radiation and corrosion, and by being compatible with multiple corrosion methods, it can truly simulate the service environment of marine engineering facilities and meet the needs of various types of tests.

[0064] The test device realizes the precise transmission of eccentric pressure through the loading block 12, and can simulate the compression-bending composite stress state caused by factors such as load asymmetry and structural geometric shape asymmetry in actual engineering, greatly improving the simulation degree of the test to the actual engineering conditions; for the strong ultraviolet radiation environment under some special working conditions, an irradiation test device 4 is specially designed, which can well simulate the changes in the mechanical properties of the structure exposed to strong ultraviolet radiation environment for a long time; through the design of the corrosion groove 31 surrounding the specimen 100, it can simulate the test conditions of spraying dry-wet cycle in the splash zone, immersion dry-wet cycle in the tidal zone, coexistence of multiple types of corrosion effects of immersion and dry-wet cycle or other corrosive environments, and can realize the regional non-uniform corrosion test of the specimen 100, either uniformly corroding it or only corroding its designated area, accurately reflecting the corrosion process of corrosive substances such as chloride ions and sulfates on steel tube concrete structures.

[0065] The structural mechanical properties testing device under the coupled effects of "long-term compression and bending load + ultraviolet radiation + corrosion" provided in this embodiment realizes the long-term compression and bending load research of the specimen 100 based on the principle of self-reaction force. It is compact and easy to move and disassemble, occupies a small area and has low requirements for the test site. It can be recycled multiple times and has significant economic advantages. The testing device can carry out mechanical property testing research of steel tube concrete under the coupled effects of long-term compression and bending load + ultraviolet radiation + corrosion, filling the gap in the long-term compression and bending load + ultraviolet radiation + corrosion testing device in the field of steel tube concrete research. The testing device is equipped with a special measuring device, which can monitor the mechanical properties of the specimen 100 under various composite effects in real time, making it convenient to draw the load-tension / compression deformation stress curve of the long-term compression and bending member of the steel tube concrete in the later stage, providing accurate data support for studying the degradation mechanism and degradation process of the steel tube concrete structure.

[0066] Example 2 Based on Example 1, this example further illustrates the specific structure of the corrosion test device. Figure 21-22 As shown, the corrosion test device further includes a water tank device 32, which can contain a corrosive liquid. Figure 15-16As shown, a drain outlet 35 can be opened at the bottom of the corrosion tank 31, and the water tank device 32 is connected to the corrosion tank 31 through an inlet pipe 321. The inlet pipe 321 is used to input the corrosion liquid into the corrosion tank 31. The drain outlet 35 is connected to the corrosion tank 31 through an outlet pipe 322. The outlet pipe 322 is used to re-input the corrosion liquid in the corrosion tank 31 into the water tank device 32. The water tank device 32 is used to transport the corrosion liquid to the corrosion tank 31.

[0067] The water tank device 32 is connected to the corrosion tank 31 through the water inlet pipe 321 and the water outlet pipe 322, which can realize the periodic delivery and discharge of the corrosive liquid, such as a 12-hour drying and 12-hour immersion cycle, accurately simulating the high tide and low tide process in the ocean tidal zone, and can truly reflect the dry-wet cycle corrosion effect of marine engineering structures immersed in the seawater tidal zone and dried under high humidity. The tidal zone immersion dry-wet cycle corrosion test is carried out to provide real conditions for studying the corrosion characteristics of steel tube concrete in this environment and improve the accuracy of the test.

[0068] Example 3 Based on Example 1, this example further illustrates the specific structure of the corrosion test device. Figure 23-24 As shown, the corrosion test device further includes a water tank device 32, which can contain a corrosive liquid. Figure 15-16 As shown, a drain port 35 may be provided at the bottom of the corrosion tank 31, and a plurality of spray heads 311 may be provided on the inner wall of the corrosion tank 31. A water tank device 32 is connected to the spray head 311 via a water inlet pipe 321, and the drain port 35 is connected to the corrosion tank 31 via a water outlet pipe 322. The water tank device 32 is used to deliver the corrosive liquid to the corrosion tank 31. By providing a plurality of spray heads 311 on the inner wall of the corrosion tank 31, the specimen 100 is placed in an environment of alternating spraying and air drying, for example, a 12-hour drying and 12-hour spraying cycle. This can simulate the splash and atomization characteristics of seawater in the ocean splash zone, allowing for the conduct of a spray-dry-wet cycle corrosion test in the splash zone, providing realistic conditions for studying the corrosion characteristics of concrete-filled steel tubes in such an environment and improving test accuracy.

[0069] Example 4 Based on Example 1, this example further illustrates the specific structure of the corrosion test device. Figure 15-16 、 Figure 25-26As shown, the corrosion test apparatus further includes a DC power supply 33 and a cathode plate 34. The cathode plate 34 can be made of steel. There can be one or more cathode plates 34. The cathode plates 34 are located in the corrosion tank 31. The cathode of the DC power supply 33 is electrically connected to the cathode plate 34, and the anode of the DC power supply 33 can be electrically connected to the test piece 100. An electrochemical corrosion environment is established by the DC power supply 33, and the test piece 100 is used as the anode and the cathode plate 34 is used as the cathode to form an electrochemical corrosion circuit. This can significantly accelerate the corrosion process of the steel tube concrete structure, compressing the corrosion process that may take years or even decades in the natural environment to a time range acceptable to the laboratory. Conducting electrochemical accelerated corrosion tests provides real conditions for studying the corrosion characteristics of steel tube concrete in such an environment and improves the accuracy of the test.

[0070] Example 5 Based on Example 1, this example further illustrates the specific structure of the corrosion test device. Figure 15-16 、 Figure 23-24 As shown, the corrosion testing apparatus further includes a water tank assembly 32, which can hold corrosive liquid. A drain outlet 35 can be provided at the bottom of the corrosion tank 31, and a plurality of spray heads 311 can be provided on the inner wall of the corrosion tank 31. The water tank assembly 32 is connected to the spray heads 311 via a water inlet pipe 321, and the drain outlet 35 is connected to the corrosion tank 31 via a water outlet pipe 322. The water tank assembly 32 is used to deliver corrosive liquid to the corrosion tank 31. During use, the corrosive liquid can be injected into the corrosion tank 31 according to the submersion height required by the test, so that a predetermined height range below the test piece 100 (for example, half the height of the test piece 100) is immersed in the corrosive liquid to conduct the immersion corrosion test. The upper spray head 311 is opened periodically to spray the upper part of the specimen 100 for dry-wet cycle corrosion; or the upper spray head 311 is opened (the water inlet pipe 321 can also be used directly) to change the liquid level of the corrosive liquid, and the upper part of the specimen 100 is immersed in dry-wet cycle corrosion. The corrosion test device is designed to simultaneously carry out different types of corrosion tests on different predetermined areas of the specimen 100, that is, immersion and dry-wet cycle multi-type corrosion effects coexist in tests, thereby simulating more complex corrosion environment conditions.

[0071] Example 6 This embodiment provides a method for testing the mechanical properties of a structure under the multi-working condition coupling of "long-term compression and bending load + ultraviolet radiation + corrosion", using the "long-term compression and bending load + ultraviolet radiation + corrosion" multi-working condition coupling test device provided in any one of Embodiment 2, Embodiment 3, Embodiment 4, or Embodiment 5, and comprising the following steps: S1: Before conducting the mechanical performance test of the steel tube concrete structure, you can first carry out preparatory work before the test, specifically, Figures 11 to 16 、 Figure 21-22As shown, it includes: determining the material used for the steel tube concrete specimen 100, the cross-sectional type and size of the outer steel tube, and determining the compressive eccentricity of the specimen 100.

[0072] The dimensions of each component of the test device are adjusted according to the parameters of the specimen 100. The following should be noted during the design: (1) The yield strength of the steel material of each plate 11, the load-bearing plate 21, the loading block 12 and the knife-edge hinge 24 should be higher than the yield strength of the steel pipe of the specimen 100 to ensure sufficient rigidity; (2) The height of the tie rod 23 should be lower than the overall height of the structural mechanical performance test device under the multi-working condition coupling of "long-term compression and bending load + ultraviolet radiation + corrosion" after long-term loading is completed, so as to facilitate the ultimate bearing capacity test loading after long-term load holding; (3) The cross-section of the corrosion groove 31 should be designed as much as possible with the cross-section of the outer steel pipe of the specimen 100, and try to ensure that the distance between any point on the inner wall of the corrosion groove 31 and the nearest outer surface of the outer steel pipe of the specimen 100 is consistent.

[0073] The upper and lower bearing plates 21, two loading blocks 12 and two knife-edge hinges 24 of the bending test device 2 are cut and processed; the specimen end plate 1 is processed, the loading blocks 12 are welded at the corresponding positions of the top of the upper plate 11 of the specimen 100 and the bottom of the lower plate 11 of the specimen 100, and grooves that are just coupled with the knife-edge hinges 24 are cut at the corresponding positions of the designed pressure-bearing positions of the loading blocks 12. The loading blocks 12 are eccentrically set relative to the specimen 100.

[0074] Weld the outer steel pipe of the specimen 100 to the upper part of the lower plate 11 of the specimen 100, and weld stiffening ribs 13 to the lower plate 11 of the specimen 100 if necessary; complete the pouring of concrete in the steel pipe and maintain for 28 days; weld the other plate 11 to the top of the specimen 100, and weld stiffening ribs 13 to the upper plate 11 of the specimen 100 if necessary, to complete the fixed connection between the two ends of the specimen 100 and the plate 11 respectively; process the corrosion groove 31 according to the test requirements, and use waterproof glue to bond the irradiation test device 4 to the inner wall of the corrosion groove 31. The corrosion groove 31 is usually designed as two symmetrical halves, with a slot 36 set in the middle for connection, that is, the corrosion groove 31 and the bending test device 2 are detachably connected; the specimen 100 is inserted into the corrosion groove 31 and the corrosion groove 31 is connected as a whole with the slot 36, and insulating paint or epoxy resin is sprayed inside and outside the slot 36 of the corrosion groove 31, and then the gap between the bottom of the corrosion groove 31 and the specimen 100 is waterproofed with epoxy resin, so that the corrosion groove 31 surrounds the specimen 100; two knife-edge hinges 24 are welded to the center positions of the upper and lower bearing plates 21 respectively; the pull rod 23 is inserted into the lower bearing plate 21 and the lower nut 22 is installed, and the loading block 12 on the lower plate body 11 connected to the specimen 100 is placed on the lower knife-edge hinge 24. A small amount of fine sand can be sprinkled on the connection between the knife-edge hinge 24 and the groove of the loading block 12 to enhance friction.

[0075] The strain gauge 51 is bonded to the specified position of the specimen 100 and sealed with tape and epoxy resin. The upper knife-edge hinge 24 is placed in the concave side of the loading block 12 on the upper plate 11 connected to the specimen 100. The compressive load sensor 53 is installed on the upper part of the pull rod 23, between the upper bearing plate 21 and the nut 22. The nut 22 on the upper part of the compressive load sensor 53 is tightened. The compressive load sensor 53, the upper bearing plate 21 and the specimen 100 are fixed by the force applied by the nut 22. The micrometer 52 is installed on the top of the upper bearing plate 21. The strain gauge 51, the micrometer 52 and the compressive load sensor 53 are connected to test whether they can work normally. If there is no abnormality, the subsequent mechanical properties research of the steel tube concrete structure will be started.

[0076] S2: If Figure 13-14 As shown, a long-term bending load test is carried out on the specimen 100 using the bending test device 2; like Figures 21 and 22 As shown, the irradiation test device 4 is powered on, and the irradiation test device 4 is used to carry out an ultraviolet irradiation test on the test piece 100.

[0077] A corrosion test device is used to conduct a corrosion test on the specimen 100. In this embodiment, a tidal zone immersion dry-wet cycle corrosion test is used as an example for description: When conducting a tidal zone immersion wet-dry cycle corrosion test, the corrosion test device provided in Example 2 can be used. The corrosion test device includes a water tank device 32, which is connected to the corrosion tank 31 through an inlet pipe 321 and an outlet pipe 322. The water tank device 32 is used to transport the corrosive liquid to the corrosion tank 31; the corrosive liquid in the corrosion tank 31 is filled or emptied at regular intervals to place the specimen 100 in an environment where immersion and air drying alternate, for example, a 12-hour drying and 12-hour immersion cycle.

[0078] Monitor the information of the strain gauge 51, micrometer 52, compressive load sensor 53 and other monitoring devices in real time. If the load drops during the long-term compressive bending load, reload it in time. If the ultraviolet radiation intensity drops, replace the fluorescent ultraviolet lamp in time. Replace the corrosive liquid regularly to ensure stable concentration.

[0079] S3: Complete long-term bending test, corrosion test, and UV radiation test.

[0080] The structural mechanical performance testing method under the coupled action of multiple working conditions of "long-term compression and bending load + ultraviolet radiation + corrosion" provided in this embodiment can simultaneously carry out long-term compression and bending tests, corrosion tests and ultraviolet radiation tests, and successfully realizes the simulation of the coupled action of the three environmental factors of "long-term compression and bending load + ultraviolet radiation + corrosion", filling the gap in the test methods in this field. By eccentrically setting the loading block 12 relative to the specimen 100, the compression and bending composite stress state caused by factors such as load asymmetry and structural geometric shape asymmetry in actual engineering is accurately simulated, thereby improving the authenticity of the test simulation of actual engineering conditions.

[0081] Furthermore, after the bending test, corrosion test and UV irradiation test, if Figure 27-28 As shown in the figure, it is also possible to carry out an ultimate bearing capacity failure test under the premise of long-term bending load without unloading, which includes the following steps: S4: Keep the bending test device 2 unloaded, loosen the slot 36 to remove the corrosion test device, remove the micrometer 52, and place the bending test device 2 on the pressure testing machine 6 to which the upper and lower test machine end plates (steel plates) have been installed (the pressure testing machine 6 is usually provided with upper and lower loading plates. The upper and lower test machine end plates mentioned here are end plates installed on the upper and lower loading plates. The installation method depends on the equipment model, loading plate size, and hole setting). The upper and lower bearing plates 21 of the bending test device 2 are respectively welded and fixed to the upper and lower test machine end plates of the pressure testing machine 6 (bolt connection or further installation of fixing grooves can also be provided at the connection between the two to enhance the connection performance between the two).

[0082] S5: After using the pressure testing machine 6 to preliminarily load the specimen 100 to a value exceeding the design long-term load value of the specimen 100, remove the nut 22 and the pull rod 23, and continue to use the pressure testing machine 6 to load the specimen 100 until the specimen 100 is destroyed, thereby realizing a compression bending ultimate bearing capacity destruction test under the condition of long-term compression bending load without unloading (i.e., the specimen 100 does not deform and rebound under the long-term compression bending load).

[0083] In traditional testing methods, after a long-term compression and bending load is applied, before conducting a steel tube concrete structure ultimate bearing capacity failure test, it is usually necessary to unload the structure after the long-term load test is completed, remove the long-term device (i.e., remove the long-term holding load on the steel tube concrete structure), and then reload the steel tube concrete structure to failure. This causes the deformation of the steel tube concrete structure under the long-term load to rebound before the ultimate bearing capacity loading is performed, resulting in a large test error. The structural mechanical performance testing method under the multi-condition coupling of "long-term compression and bending load + ultraviolet irradiation + corrosion" provided by the present invention can first remove the corrosion test device, nut 22, tie rod 23 and other devices that may interfere with the compression and bending ultimate bearing capacity test before conducting the compression and bending ultimate bearing capacity test. The compression and bending ultimate bearing capacity test can be directly performed while keeping the compression and bending test device 2 unloaded, thereby clarifying the full-life working mechanism of steel tube concrete structures in offshore and coastal areas under long-term compression and bending loads until final failure.

[0084] Example 7 The difference from Example 6 is that this embodiment can use the corrosion test device provided in Example 3 to carry out the splash zone spray dry-wet cycle corrosion test. Figure 23-24 As shown, the corrosion test device includes a water tank device 32, and a plurality of spray heads 311 are set on the inner wall of the corrosion tank 31. The water tank device 32 is connected to the spray head 311 through a water inlet pipe 321. The water tank device 32 is also connected to the corrosion tank 31 through a water outlet pipe 322. The water tank device 32 is used to transport the corrosive liquid to the corrosion tank 31; the spray head 311 is used to spray the corrosive liquid on the surface of the specimen 100 at a regular time, for example, a 12-hour drying and 12-hour spraying cycle, so that the specimen 100 is in an environment where spraying and air-drying alternate.

[0085] Example 8 The difference from Example 6 is that this embodiment can use the corrosion test device provided in Example 4 to carry out electrochemical accelerated corrosion test. Figure 25-26 As shown, the corrosion test device includes a DC power supply 33 and a cathode plate 34. The cathode plate 34 is located in the corrosion tank 31. The cathode of the DC power supply 33 is electrically connected to the cathode plate 34, and the anode of the DC power supply 33 is electrically connected to the test piece 100. Corrosion liquid is poured into the corrosion tank 31, and the electrochemical accelerated corrosion test is started after the current path is detected to be correct.

[0086] When conducting an electrochemical accelerated corrosion test, the thickness of the cathode plate 34 shall not be less than the designed corrosion thickness of the outer steel pipe of the specimen 100 and shall be consistent with the cross-sectional type of the outer steel pipe of the specimen 100, ensuring that the distance between any point on the inner wall of the corrosion groove 31 and the nearest outer surface of the outer steel pipe of the specimen 100 is consistent to ensure the accuracy of the test results.

[0087] Example 9 Different from Example 6, this embodiment can use the corrosion test device provided in Example 5 to carry out immersion and dry-wet cycle multi-type corrosion coexistence tests. Figure 15-16 、 Figure 23-24 As shown, the corrosion test device includes a water tank device 32, which can hold corrosive liquid. A drain port 35 can be opened at the bottom of the corrosion tank 31, and a plurality of spray heads 311 can be set on the inner wall of the corrosion tank 31. The water tank device 32 is connected to the spray head 311 through an inlet pipe 321, and the drain port 35 is connected to the corrosion tank 31 through an outlet pipe 322. The water tank device 32 is used to transport corrosive liquid to the corrosion tank 31. The corrosive liquid in the corrosion tank 31 is injected according to the submergence height required by the test, so that a specific height range of the lower part of the specimen 100 is immersed in the corrosive liquid to carry out an immersion corrosion test, and the spray head 311 above the liquid level of the corrosive liquid in the corrosion tank 31 is used to spray the upper part of the specimen 100 for dry-wet cycle corrosion, or the water inlet pipe 321 is directly used to immerse the upper part of the specimen 100 for dry-wet cycle corrosion. The corrosion test device is designed to simultaneously carry out different types of corrosion tests on different specific areas of the specimen 100, that is, immersion and dry-wet cycle multi-type corrosion effects coexist in the test, thereby simulating more complex corrosion environment conditions.

[0088] 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. A structural mechanical performance test device under multi-working condition coupling, characterized in that: The invention can simultaneously realize the coupling effects of long-term compression-bending load, ultraviolet radiation and corrosion on the steel tube concrete specimen (100), including: Two specimen end plates (1), the specimen end plates (1) comprising a plate body (11), a loading block (12) being provided on one side of the plate body (11), the loading block (12) being used to transmit eccentric pressure to the specimen (100), and the plate body (11) being used to be fixedly connected to the specimen (100); A compression bending test device (2), the compression bending test device (2) being connected to the loading block (12), and the compression bending test device (2) being used to apply pressure to the test piece (100) from both the upper and lower ends; A corrosion testing device, comprising a corrosion groove (31), the corrosion groove (31) enclosing the test piece (100), and the corrosion testing device is used to perform a corrosion test on the test piece (100); an irradiation test device (4), the irradiation test device (4) being installed on a side of the corrosion tank (31) facing the test piece (100), the irradiation test device (4) being used to perform an ultraviolet irradiation test on the test piece (100); A measuring device is provided, wherein the measuring device is used to measure the mechanical properties of the test piece (100) under the action of at least one of the compression and bending test device (2), the corrosion test device, and the irradiation test device (4).

2. The structural mechanical performance testing device under multiple working conditions coupling according to claim 1 is characterized in that: The compression bending test device (2) includes two oppositely arranged bearing plates (21), the bearing plates (21) are connected to the pull rod (23) through a nut (22), and the nut (22) is used to adjust the bearing plates (21) to move closer to or farther away from each other under the guidance of the pull rod (23). The opposite surfaces of the two bearing plates (21) are provided with a knife-edge hinge (24), and the knife-edge hinge (24) is concavely matched with the loading block (12).

3. The structural mechanical performance testing device under multiple working conditions coupling according to claim 1 is characterized in that: The corrosion test device further comprises a water tank device (32), wherein the water tank device (32) is connected to the corrosion tank (31) via a water inlet pipe (321) and a water outlet pipe (322), and the water tank device (32) is used to transport the corrosion liquid to the corrosion tank (31).

4. The structural mechanical performance testing device under multiple working conditions coupling according to claim 1 is characterized in that: The corrosion test device further includes a water tank device (32). A plurality of spray heads (311) are provided on the inner wall of the corrosion tank (31). The water tank device (32) is connected to the spray heads (311) via a water inlet pipe (321). The water tank device (32) is also connected to the corrosion tank (31) via a water outlet pipe (322). The water tank device (32) is used to transport the corrosion liquid to the corrosion tank (31).

5. A structural mechanical performance testing device under multiple working conditions coupling according to any one of claims 1 to 4, characterized in that: The corrosion test device further comprises a DC power supply (33) and a cathode plate (34), wherein the cathode plate (34) is located in the corrosion tank (31), the cathode of the DC power supply (33) is electrically connected to the cathode plate (34), and the anode of the DC power supply (33) can be electrically connected to the test piece (100).

6. The structural mechanical performance testing device under multiple working conditions coupling according to claim 1 is characterized in that: The irradiation test device (4) comprises a fluorescent ultraviolet lamp tube, and the electromagnetic wave wavelength of the fluorescent ultraviolet lamp tube is ≥250nm.

7. The structural mechanical performance testing device under multiple working conditions coupling according to claim 2 is characterized in that: The measuring device comprises a strain gauge (51), a micrometer (52) and a compressive load sensor (53), wherein the strain gauge (51) is mounted on the test piece (100), the micrometer (52) is mounted on the bearing plate (21), and the compressive load sensor (53) is mounted between the bearing plate (21) and the nut (22).

8. A method for testing the mechanical properties of a structure under multiple working conditions coupling, characterized in that: A structural mechanical performance testing device under multiple working condition coupling as described in any one of claims 1 to 7 is used, comprising the following steps: S1: Welding the two ends of the test piece (100) to the plate (11) respectively, and setting the loading block (12) eccentrically relative to the test piece (100); using the corrosion groove (31) to enclose the test piece (100), and the corrosion groove (31) is detachably connected to the compression bending test device (2); S2: using the compression bending test device (2) to carry out a long-term compression bending load test on the specimen (100), using the corrosion test device to carry out a corrosion test on the specimen (100), using the irradiation test device (4) to carry out an ultraviolet irradiation test on the specimen (100), and monitoring the information of the measuring device in real time; S3: Complete long-term bending test, corrosion test, and UV radiation test.

9. The method for testing structural mechanical properties under multi-working condition coupling according to claim 8, characterized in that: In S2, a corrosion test device is used to conduct a corrosion test on the specimen (100), including at least one of a tidal zone immersion dry-wet cycle corrosion test, a splash zone spray dry-wet cycle corrosion test, an electrochemical accelerated corrosion test, and a test of multiple types of corrosion effects coexisting with immersion and dry-wet cycle; When conducting a tidal zone immersion dry-wet cycle corrosion test, the corrosion test device includes a water tank device (32), the water tank device (32) is connected to the corrosion tank (31) through a water inlet pipe (321) and a water outlet pipe (322), and the water tank device (32) is used to transport the corrosion liquid to the corrosion tank (31); the corrosion liquid in the corrosion tank (31) is filled or emptied at regular intervals, so that the test piece (100) is in an environment of alternating immersion and air drying; When carrying out a spray dry-wet cycle corrosion test in a splash zone, the corrosion test device includes a water tank device (32), a plurality of spray heads (311) are provided on the inner wall of a corrosion tank (31), the water tank device (32) is connected to the spray heads (311) via a water inlet pipe (321), the water tank device (32) is connected to the corrosion tank (31) via a water outlet pipe (322), and the water tank device (32) transports the corrosive liquid to the corrosion tank (31); the spray heads (311) are used to spray the corrosive liquid on the surface of the test piece (100) at regular intervals, so that the test piece (100) is placed in an environment of alternating spraying and air drying; When conducting an electrochemical accelerated corrosion test, the corrosion test device includes a DC power supply (33) and a cathode plate (34), the cathode plate (34) is located in a corrosion tank (31), the cathode of the DC power supply (33) is electrically connected to the cathode plate (34), and the anode of the DC power supply (33) is electrically connected to the test piece (100); after pouring the corrosion liquid into the corrosion tank (31), the electrochemical accelerated corrosion test is started; When conducting a test for the coexistence of multiple types of corrosion effects such as immersion and dry-wet cycles, the corrosion test device includes a water tank device (32), a plurality of spray heads (311) are arranged on the inner wall of the corrosion tank (31), the water tank device (32) is connected to the spray heads (311) through a water inlet pipe (321), and the water tank device (32) is connected to the corrosion tank (31) through a water outlet pipe (322), so that a predetermined area below the test piece (100) is in an immersion environment, and a predetermined area above the test piece (100) is in a spray dry-wet cycle environment or an immersion dry-wet cycle environment.

10. The method for testing structural mechanical properties under multi-working condition coupling according to claim 8, characterized in that: The compression bending test device (2) comprises two oppositely arranged bearing plates (21), wherein the bearing plates (21) are connected to the pull rod (23) via nuts (22), and the nuts (22) are used to adjust the bearing plates (21) to move closer to or farther from each other under the guidance of the pull rod (23); and further comprises the following steps: S4: Keep the bending test device (2) unloaded, remove the corrosion test device, place the bending test device (2) in the pressure testing machine (6), and fix the bearing plates (21) to the loading plates of the pressure testing machine (6); S5: After initially loading the specimen (100) using the pressure testing machine (6) to a load exceeding the design long-term load value of the specimen (100), the nut (22) and the tie rod (23) are removed, and the pressure testing machine (6) is used to continue loading the specimen (100) until the specimen (100) is destroyed.

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