A push-out test device and method for corrugated steel pipe reinforced concrete column considering secondary load

Abstract

The application provides a push-out test device and method of a corrugated steel pipe reinforced concrete column considering secondary load, and belongs to the technical field of building structure test, to solve the problem that the existing push-out test device cannot compensate the creep deformation of concrete during the load-holding process when measuring, and the technical points are as follows: the device comprises a supporting column, hydraulic jacks are arranged on the left and right sides of the supporting column, a first pad plate is fixedly connected above the hydraulic jacks, a linear displacement sensor is installed above the first pad plate, and a corrugated steel pipe is arranged in the middle of the first pad plate. The first strain gauge, the second strain gauge and the third strain gauge arranged at the wave crest, the wave abdomen and the wave trough of the corrugated steel pipe enable the device to measure the resistance strain gauge at the wave crest, the wave abdomen and the wave trough of the corrugated steel pipe, the spring enables the device to compensate the creep deformation of concrete during the load-holding process when measuring, N1 is kept unchanged, then the secondary load is applied, and the stability of the pre-pressing axial force is maintained.

Description

Technical Field

[0001] This invention relates to the field of building structure testing or experimental technology, specifically to a test device and method for pushing out corrugated steel pipe reinforced concrete columns considering secondary loads. Background Technology

[0002] Damage such as cracks and oxidation on the surface of the pier directly affects the bond performance between the pier and the concrete. In addition, during the service life of the pier, various forces may cause slight displacement or deformation, which can also affect the interfacial bond performance. Therefore, it is necessary to measure the slippage of the pier. However, existing slippage measurement devices still have some shortcomings in use.

[0003] For example, CN110296933A discloses a bond-slip measuring device for a steel-concrete composite column push-out test. Using this device, the free end slip value of the steel-concrete composite column can be measured. The extended threaded vertical rod is pre-embedded in the steel-concrete composite column during component fabrication, and the extended horizontal rod and the extended threaded vertical rod are reliably connected by bolts, ensuring sufficiently stable and accurate measurement of the free end bond-slip value. The design of the measuring device allows for easy measurement of the free end displacement of the steel-concrete composite column after connecting the extended horizontal rod and tightening the movable bolts, using a displacement gauge. Installation is easy and operation is convenient. While the aforementioned push-out test device is convenient to install, it cannot perform strain testing at the crests, antinodes, and troughs of the corrugated steel pipe, lacks secondary loading capabilities, and cannot compensate for concrete creep deformation during load holding. Summary of the Invention

[0004] In view of the problems existing in the existing push-out test device, namely that the existing push-out test device cannot compensate for the creep deformation of concrete during the load-bearing process, this invention proposes a push-out test device and method for corrugated steel pipe reinforced reinforced concrete columns that takes into account secondary loads.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a corrugated steel pipe reinforced reinforced concrete column push-out test device considering secondary load, comprising a support column, hydraulic jacks on the left and right sides of the support column, a first pad fixedly connected above the hydraulic jacks, a linear displacement sensor installed above the first pad, a corrugated steel pipe in the middle of the first pad, a concrete pier inside the corrugated steel pipe, the concrete pier being connected to the support column by a spring, an electronic slip gauge installed inside the concrete pier, a second pad connected to the top of the corrugated steel pipe, dial indicators on the left and right sides of the second pad, a force sensor installed above the second pad, a screw jack connected above the force sensor, a first strain gauge installed on the surface of the corrugated steel pipe, a second strain gauge below the first strain gauge, and a third strain gauge below the second strain gauge.

[0006] As a preferred embodiment of the present invention, the interior of the first pad has a lattice structure, the hydraulic jacks are symmetrically distributed on the left and right sides of the first pad, a drive assembly is installed on the surface of the first pad, a marking assembly is provided on the outer side of the top of the drive assembly, a pressure plate is provided between the marking assembly and the drive assembly, an extension plate is provided on the left side of the drive assembly, and a fixing sleeve is fixedly connected to the top of the extension plate.

[0007] As a preferred embodiment of the present invention, the central axes of the corrugated steel pipe, the second pad, and the spiral jack are on the same straight line, and there is a gap between the corrugated steel pipe and the concrete pier.

[0008] As a preferred embodiment of the present invention, the linear displacement sensor is a differential transformer displacement sensor, and the linear displacement sensor is symmetrically distributed on the left and right sides of the first pad.

[0009] As a preferred embodiment of the present invention, the first strain gauge is located at the crest of the corrugated steel pipe, the second strain gauge is located at the antinode of the corrugated steel pipe, and the third strain gauge is located at the trough of the corrugated steel pipe.

[0010] As a preferred embodiment of the present invention, the drive assembly includes a rotating groove formed on the top of a first pad, a movable rod slidably mounted inside the rotating groove, a motor fixedly mounted on the left front side of the upper surface of the first pad, a connecting rod fixedly connected to the output shaft of the motor, a gear fitted to the outer side of the connecting rod, a gear ring meshing with the outer side of the gear, the bottom of the gear ring connected to the movable rod, the left side of the gear ring connected to an extension plate, connecting blocks fixedly mounted around the connecting rod, damping blocks fixedly connected to the side of the connecting blocks, a mating groove formed on the upper surface of the gear, a fixed connection between the connecting rod and the pressure plate, and a through hole for the connecting rod to pass through in the middle of the gear.

[0011] As a preferred embodiment of the present invention, the damping block is hemispherical in shape and made of rubber. The outer wall of the lower half of the damping block is in contact with the inner wall of the mating groove. The mating grooves are evenly distributed on the surface of the gear, and the position and number of the mating grooves correspond one-to-one with the position and number of the damping blocks.

[0012] As a preferred embodiment of the present invention, the fixing sleeve is made of high-hardness rubber material, a first air nozzle is installed on the top of the fixing sleeve, the inside of the fixing sleeve is hollow, and a cross slit is opened in the middle of the first air nozzle.

[0013] As a preferred embodiment of the present invention, the marking assembly includes a fixing ring fixedly installed on the top of the gear, a rubber sleeve fixedly disposed on the top of the fixing ring, a second air nozzle disposed on the surface of the rubber sleeve, and the pressure plate forming a pressing structure with the rubber sleeve through a connecting rod.

[0014] A method for push-out test of corrugated steel pipe reinforced reinforced concrete column considering secondary loads includes the following steps:

[0015] S1: To strengthen the reinforced concrete pier under load, a screw jack is used to apply a preload axial force N1 to the top of the concrete pier. At the same time, a spring is placed at the bottom of the pier to compensate for the creep deformation of the concrete during the load-bearing process, maintain the stability of the preload axial force, eliminate the creep effect, and keep the preload axial force N1 constant.

[0016] S2: During reinforcement, keep the position of the spiral jack unchanged, attach the corrugated steel pipe to the outside of the concrete pier, place it on the first lattice pad, and use it as a grouting template for grouting; during the push-out test, the four hydraulic jacks under the first pad apply the load simultaneously, and the secondary load force is N2.

[0017] S3: The force exerted is measured by a force sensor. The relative slippage at the upper end of the new and old interface of the concrete pier is measured by an electronic dial gauge. The relative slippage at the middle, quarter point and lower end of the concrete pier is measured by an embedded electronic slip gauge. The longitudinal and transverse strain of the concrete and the longitudinal strain of the grout are measured by an embedded electronic slip gauge. The strain at the crest, antinode and trough of the corrugated steel pipe is measured by resistance strain gauges: the first strain rosette, the second strain rosette and the third strain rosette.

[0018] S4: Based on the experimental results, the failure mechanism of the new and old interfaces of corrugated steel pipe reinforced reinforced concrete piers is revealed, the bond-slip constitutive relationship is established, and the influence of existing damage and interface treatment methods on the interface bonding performance of concrete piers is studied.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. By setting the first, second, and third strain gauges at the crests, antinodes, and troughs of the corrugated steel pipe, the device can perform resistance strain gauge measurements at the crests, antinodes, and troughs of the corrugated steel pipe during the push-out test, thus solving the defect of existing measuring devices that cannot perform strain testing at the crests, antinodes, and troughs of the corrugated steel pipe.

[0021] 2. Four hydraulic jacks under the lattice plate apply loads simultaneously, and the pushing force is measured by force sensors; the relative slippage of the upper end of the new and old interface of the pier column is measured by an electronic dial gauge, and the relative slippage of the middle, quarter point and lower end of the pier column is measured by an embedded electronic slip gauge; the longitudinal and transverse strain of the concrete and the longitudinal strain of the grout are measured by embedded strain gauges to reveal the failure mechanism of the new and old interface of the corrugated steel pipe reinforced concrete pier column. The springs can eliminate the creep of the concrete, keep N1 constant, maintain the stability of the preload axial force, and then apply N2 (secondary load).

[0022] 3. Through the gears and gear rings on the device, the device can drive the gears to rotate via the connecting rod. When the gear rotation resistance is too high, the damping blocks around the connecting rod will disengage from the inside of the mating groove and move to the next mating groove, causing the connecting rod to slide inside the gear. At this time, the gear remains fixed, allowing the pressure plate to press against the rubber sleeve, allowing the marking liquid inside the rubber sleeve to be sprayed out, thus achieving the marking function. When the corrugated steel pipe deforms, the movement resistance of the fixed sleeve inside the corrugated steel pipe increases, creating a speed difference between the gear and the connecting rod, thereby achieving the marking function. The operator can observe whether there is marking liquid on the left front side of the corrugated steel pipe to determine whether the corrugated steel pipe is deformed enough. This improves the functionality of the device and solves the defect of the existing push-out test device that cannot automatically mark when the corrugated steel pipe is compressed. This device has the advantage of better performance.

[0023] 4. By using a hollow fixed sleeve, the device can adjust the degree of expansion of the fixed sleeve through the first air nozzle, thereby adjusting the gap between the expanded fixed sleeve and the corrugated steel pipe. This allows the rotational resistance of the gears to change when the corrugated steel pipe deforms, enabling the device to perform marking work under different deformation conditions. This improves the adjustability of the device and solves the defect of existing push-out test devices that cannot adjust the accuracy of corrugated steel pipe deformation testing as needed. This device has the advantage of a higher degree of adjustability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 This is a schematic diagram of the overall structure of the corrugated steel pipe reinforced reinforced concrete column push-out test device considering secondary load of the present invention (the slurry is located between the concrete pier 5 and the corrugated steel pipe 7).

[0026] Figure 2 This is a front view structural diagram of the present invention;

[0027] Figure 3 yes Figure 1 Schematic diagram of the structure at point A in the middle;

[0028] Figure 4 This is a schematic diagram of the corrugated steel pipe and the fixing sleeve fitting structure of the present invention;

[0029] Figure 5 yes Figure 4 Schematic diagram of the structure at point B;

[0030] Figure 6 yes Figure 4 Schematic diagram of the structure at point C;

[0031] Figure 7 This is a schematic diagram of the disassembled structure of the gear and connecting rod of the present invention;

[0032] Figure 8 This is a schematic diagram of the connection structure between the connecting rod and the pressure plate of the present invention;

[0033] Figure 9 This is a top-section structural schematic diagram of the damping block of the present invention.

[0034] Reference numerals: 1. Support column; 2. Hydraulic jack; 3. First pad; 4. Spring; 5. Concrete pier; 6. Electronic slip gauge; 7. Corrugated steel pipe; 8. Linear displacement sensor; 9. Second pad; 10. Dial gauge; 11. Force sensor; 12. Screw jack; 13. First strain gauge; 14. Second strain gauge; 15. Third strain gauge; 16. Through hole; 17. Cross-shaped slit; 18. Drive Components; 1801, Rotary groove; 1802, Movable rod; 1803, Motor; 1804, Connecting rod; 1805, Gear; 1806, Gear ring; 1807, Connecting block; 1808, Damping block; 1809, Connecting groove; 19, Extension plate; 20, Fixing sleeve; 21, First air nozzle; 22, Marking assembly; 2201, Fixing ring; 2202, Rubber sleeve; 2203, Second air nozzle; 23, Pressure plate. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0038] Example

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] like Figures 1-9 As shown, a test device for pushing out a corrugated steel pipe reinforced reinforced concrete column considering secondary loads includes a support column 1, hydraulic jacks 2 on both sides of the support column 1, a first pad 3 fixedly connected above the hydraulic jacks 2, a linear displacement sensor 8 installed above the first pad 3, a corrugated steel pipe 7 in the middle of the first pad 3, a concrete pier 5 inside the corrugated steel pipe 7, the concrete pier 5 connected to the support column 1 by a spring 4, and an electronic slip gauge 6 installed inside the concrete pier 5. A second pad 9 is connected to the top of the corrugated steel pipe 7. A dial indicator 10 is installed on both sides of the second pad 9. A force sensor 11 is installed above the second pad 9. A screw jack 12 is connected above the force sensor 11. A first strain gauge 13 is installed on the surface of the corrugated steel pipe 7. A second strain gauge 14 is located below the first strain gauge 13. A third strain gauge 15 is located below the second strain gauge 14. The first strain gauge 13, second strain gauge 14, and third strain gauge 15 can detect the strain of the undulating section of the corrugated steel pipe 7. Figure 1As shown, to achieve reinforcement of the reinforced concrete pier 5 under load, a screw jack 12 is used to apply a preload axial force N1 to the top of the concrete pier 5. Simultaneously, a spring 4 is placed at the bottom of the pier to compensate for the creep deformation of the concrete during the load-bearing process, maintaining the stability of the preload axial force, eliminating creep, and keeping the preload axial force N1 constant. During reinforcement, the screw jack 12 is kept in the same position. Corrugated steel pipe 7 is fastened to the outer perimeter of the concrete pier 5, placed on the first pad 3, and used as a grouting template for pouring grout. During the push-out test, four hydraulic jacks 2 under the first pad 3 apply loads simultaneously, with a secondary load force of N2. The push-out force is measured by a force sensor 11. The relative slippage of the upper end of the new and old interfaces of the concrete pier 5 is measured by an electronic dial gauge 10, while the relative slippage of the middle, quarter-points, and lower end of the concrete pier 5 is measured by an internal... The longitudinal and transverse strains of the concrete and the longitudinal strain of the grout were measured using embedded electronic slip gauges 6. The strains at the crests, antinodes, and troughs of the corrugated steel pipe 7 were measured using resistance strain gauges: the first strain gauge 13, the second strain gauge 14, and the third strain gauge 15. Based on the experimental results, the failure mechanism of the new and old interfaces of the corrugated steel pipe 7 reinforced reinforced concrete pier 5 was revealed, the bond-slip constitutive relationship was established, and the influence of existing damage and interface treatment methods on the interface bonding performance of the concrete pier 5 was studied.

[0041] In this example, the first pad 3 has a lattice structure inside, and the hydraulic jacks 2 are symmetrically distributed on the left and right sides of the first pad 3. The lattice structure of the first pad 3 can ensure the overall strength. The symmetrically distributed hydraulic jacks 2 can apply loads synchronously in the future, so that the test device can be pushed out to perform bonding performance testing. A drive assembly 18 is installed on the surface of the first pad 3. A marking assembly 22 is set on the outer side of the top of the drive assembly 18. A pressure plate 23 is set between the marking assembly 22 and the drive assembly 18. An extension plate 19 is set on the left side of the drive assembly 18. A fixing sleeve 20 is fixedly connected to the top of the extension plate 19. The marking assembly 22 enables the device to automatically spray marking liquid when the corrugated steel pipe 7 deforms while the drive assembly 18 is working, which improves the functionality of the device and makes it easier for subsequent staff to determine the time and position of the deformation of the corrugated steel pipe 7, thus improving the convenience of use.

[0042] In this example, the central axes of the corrugated steel pipe 7, the second pad 9, and the spiral jack 12 are on the same straight line to ensure the stability of the device during use. There is a gap between the corrugated steel pipe 7 and the concrete pier 5, which facilitates the subsequent pouring of grouting material and thus enables the push-out test, thereby improving the functionality of the device.

[0043] In this example, the linear displacement sensor 8 is a differential pressure displacement sensor. The linear displacement sensor 8 is symmetrically distributed on the left and right sides of the first pad 3. The differential pressure displacement sensor can improve the accuracy of displacement detection, thereby enabling the device to ensure the accuracy of the test when it is pushed out.

[0044] In this example, the first strain gauge 13 is located at the crest of the corrugated steel pipe 7, the second strain gauge 14 is located at the antinode of the corrugated steel pipe 7, and the third strain gauge 15 is located at the trough of the corrugated steel pipe 7. The first strain gauge 13, the second strain gauge 14, and the third strain gauge 15 are located at the crest, antinode, and trough of the corrugated steel pipe 7, respectively, which enables the device to perform high-precision strain testing on the corrugated steel pipe 7 and improves the test accuracy of the device.

[0045] In this example, the drive assembly 18 includes a slot 1801 formed on the top of the first pad 3. A movable rod 1802 is slidably mounted inside the slot 1801. A motor 1803 is fixedly mounted on the left front side of the upper surface of the first pad 3. A connecting rod 1804 is fixedly connected to the output shaft of the motor 1803. A gear 1805 is fitted to the outer side of the connecting rod 1804. A gear ring 1806 is meshed with the outer side of the gear 1805. The bottom of the gear ring 1806 is connected to the movable rod 1802. The left side of the gear ring 1806 is connected to the extension plate 19. Connecting blocks 1807 are fixedly mounted around the connecting rod 1804. A damping block 1808 is fixedly connected to the side of the connecting block 1807. A groove is formed on the upper surface of the gear 1805. The docking groove 1809, connecting rod 1804 and pressure plate 23 are fixedly connected. The gear 1805 has a through hole 16 in the middle for the connecting rod 1804 to pass through. When the device is working, the connecting rod 1804 can be driven to rotate by motor 1803, thereby using the friction between the connecting rod 1804 and gear 1805 to drive gear 1805 to rotate. When gear 1805 rotates, it can drive gear ring 1806 to rotate. Gear ring 1806 can drive extension plate 19 to rotate. When the rotational resistance of extension plate 19 increases, the steel pipe deforms. At this time, gear 1805 can no longer rotate, and connecting rod 1804 slides on gear 1805 so that when it stops, the rotation of connecting rod 1804 can be used for marking.

[0046] In this example, the damping block 1808 is hemispherical in shape and made of rubber. The outer wall of the lower half of the damping block 1808 fits against the inner wall of the mating groove 1809. The rubber material of the damping block 1808 allows it to move from one mating groove 1809 to the next under compression, thus realizing the function of a flexible coupling. The mating grooves 1809 are evenly distributed on the surface of the gear 1805. The position and number of the mating grooves 1809 correspond one-to-one with the position and number of the damping blocks 1808. When the gear 1805 stops rotating, the damping blocks 1808 will move along each mating groove 1809. Marking can be performed after the gear 1805 stops rotating.

[0047] In this example, the fixing sleeve 20 is made of high-hardness rubber. A first air nozzle 21 is installed on the top of the fixing sleeve 20. The inside of the fixing sleeve 20 is hollow. A cross-shaped slit 17 is opened in the middle of the first air nozzle 21. Air can be injected into the inside of the fixing sleeve 20 through the first air nozzle 21 to increase the volume of the fixing sleeve 20. This allows the device to adjust the degree of expansion of the fixing sleeve 20, thereby changing the conditions for triggering the fixing sleeve 20 to stop rotating and improving the adjustability of the device.

[0048] In this example, the marking component 22 includes a fixing ring 2201 fixedly installed on the top of the gear 1805. A rubber sleeve 2202 is fixedly provided on the top of the fixing ring 2201. A second air nozzle 2203 is provided on the surface of the rubber sleeve 2202. The pressure plate 23 forms a pressing structure with the rubber sleeve 2202 through the connecting rod 1804. Through the pressing structure on the device, when the connecting rod 1804 slides, the pressure plate 23 on the connecting rod 1804 can squeeze the rubber sleeve 2202, so that the marking liquid inside the rubber sleeve 2202 can be sprayed out, realizing the automatic marking function.

[0049] It should be noted that this invention relates to a test device and method for pushing out corrugated steel pipe reinforced concrete columns considering secondary loads. First, as... Figures 1-3The diagram illustrates the reinforcement of a reinforced concrete pier 5 under load. A screw jack 12 is used to apply a preload axial force N1 to the top of the pier 5. Simultaneously, a spring 4 is placed at the bottom of the pier to compensate for creep deformation of the concrete during the load-bearing process. Under creep, the concrete is compressed, and the spring 4 maintains N1 constant. Then, N2 (secondary load) is applied to maintain the stability of the preload axial force, eliminate creep, and keep the preload axial force N1 constant. During reinforcement, the screw jack 12 remains in the same position. Corrugated steel pipe 7 is fastened to the outer perimeter of the concrete pier 5, placed on the first pad 3, and used as a grouting template for pouring grout. During the push-out test, four hydraulic jacks 2 under the first pad 3 apply loads simultaneously, with a secondary load force of N2. The push-out force is measured by a force sensor 11. The relative slippage at the upper end of the new and old interfaces of the concrete pier 5 is measured using an electronic dial gauge 10. The relative slippage at the middle, quarter-points, and lower end of the concrete pier 5 is measured using a built-in electronic slip gauge 6. The longitudinal and transverse strains of the concrete and the longitudinal strain of the grout were measured using an embedded electronic slip gauge 6 to measure the grout volume and the slip of the existing structure. The strains at the crests, antinodes and troughs of the corrugated steel pipe 7 were measured using resistance strain gauges: the first strain gauge 13, the second strain gauge 14 and the third strain gauge 15. Based on the experimental results, the failure mechanism of the new and old interfaces of the corrugated steel pipe 7 reinforced reinforced concrete pier 5 was revealed, the bond-slip constitutive relationship was established, and the influence of existing damage and interface treatment methods on the interface bonding performance of the concrete pier 5 was studied.

[0050] like Figures 4-9As shown, during operation, the connecting rod 1804 can be driven to rotate by the motor 1803. The lower surfaces of the connecting block 1807 and damping block 1808 on the outer side of the connecting rod 1804 abut against the inside of the mating groove 1809, making the resistance between the connecting rod 1804 and the gear 1805 sufficiently large, thereby achieving the function of driving the gear 1805 to rotate. When the gear 1805 rotates, it can drive the gear ring 1806 to rotate, and the gear ring 1806 drives the extension plate 19 and the fixed sleeve 20 to rotate, while the corrugated steel pipe 7 does not deform. When the corrugated steel pipe 7 deforms, the rotational resistance of the fixed sleeve 20 increases, and the damping block 1808 moves from the docking groove 1809 to the next docking groove 1809. The connecting rod 1804 slides on the gear 1805. At this time, the pressure plate 23 on the connecting rod 1804 can abut against the rubber sleeve 2202 on the fixed ring 2201, and the marking liquid in the rubber sleeve 2202 can be automatically sprayed out to realize the function of automatic marking when the corrugated steel pipe 7 deforms, which is convenient for subsequent inspection and observation. When the device is in use, gas can be injected into the interior of the fixed sleeve 20 from the first air nozzle 21, increasing the volume of the fixed sleeve 20. This allows the device to adjust the conditions required for the sliding of the trigger gear 1805 during operation, thereby allowing the device to adjust the accuracy of the deformation test of the corrugated steel pipe 7 as needed.

[0051] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A test device for pushing out corrugated steel pipe reinforced concrete columns considering secondary loads, comprising a support column, characterized in that: Hydraulic jacks are installed on both sides of the support column. A first pad is fixedly connected above the hydraulic jacks. A linear displacement sensor is installed above the first pad. A corrugated steel pipe is installed in the middle of the first pad. A concrete pier is installed inside the corrugated steel pipe. The concrete pier is connected to the support column by a spring. An electronic slip gauge is installed inside the concrete pier. A second pad is connected to the top of the corrugated steel pipe. A dial indicator is installed on both sides of the second pad. A force sensor is installed above the second pad. A screw jack is connected above the force sensor. A first strain gauge is installed on the surface of the corrugated steel pipe. A second strain gauge is installed below the first strain gauge. A third strain gauge is installed below the second strain gauge. The first pad has a lattice structure inside. The hydraulic jacks are symmetrically distributed on the left and right sides of the first pad. A drive assembly is installed on the surface of the first pad. A marking assembly is provided on the outer side of the top of the drive assembly. A pressure plate is provided between the marking assembly and the drive assembly. An extension plate is provided on the left side of the drive assembly. A fixing sleeve is fixedly connected to the top of the extension plate. The drive assembly includes a rotating groove formed on the top of the first pad, a movable rod slidably installed inside the rotating groove, a motor fixedly installed on the left front side of the upper surface of the first pad, a connecting rod fixedly connected to the output shaft of the motor, a gear fitted to the outside of the connecting rod, a gear ring meshing with the outside of the gear, the bottom of the gear ring connected to the movable rod, the left side of the gear ring connected to the extension plate, connecting blocks fixedly installed around the connecting rod, and a damping block fixedly connected to the side of the connecting block. The first strain gauge is located at the crest of the corrugated steel pipe, the second strain gauge is located at the antinode of the corrugated steel pipe, and the third strain gauge is located at the trough of the corrugated steel pipe.

2. The test device for pushing out a corrugated steel pipe reinforced concrete column considering secondary load as described in claim 1, characterized in that: The central axes of the corrugated steel pipe, the second pad, and the spiral jack are on the same straight line, and there is a gap between the corrugated steel pipe and the concrete pier.

3. The test device for pushing out a corrugated steel pipe reinforced concrete column considering secondary load as described in claim 1, characterized in that: The linear displacement sensor is a differential transformer displacement sensor, and the linear displacement sensors are symmetrically distributed on the left and right sides of the first pad.

4. The test device for pushing out a corrugated steel pipe reinforced concrete column considering secondary load as described in claim 1, characterized in that: The gear has a mating groove on its upper surface, the connecting rod and the pressure plate are fixedly connected, and the gear has a through hole in the middle for the connecting rod to pass through.

5. The test device for pushing out a corrugated steel pipe reinforced concrete column considering secondary load as described in claim 4, characterized in that: The damping block is hemispherical in shape and made of rubber. The outer wall of the lower half of the damping block fits into the inner wall of the mating groove. The mating grooves are evenly distributed on the surface of the gear, and the position and number of the mating grooves correspond one-to-one with the position and number of the damping blocks.

6. The test device for pushing out a corrugated steel pipe reinforced reinforced concrete column considering secondary load as described in claim 1, characterized in that: The fixing sleeve is made of high-hardness rubber. A first air nozzle is installed on the top of the fixing sleeve. The inside of the fixing sleeve is hollow, and a cross slit is opened in the middle of the first air nozzle.

7. The test device for pushing out a corrugated steel pipe reinforced concrete column considering secondary load as described in claim 1, characterized in that: The marking assembly includes a fixing ring fixedly installed on the top of the gear, a rubber sleeve fixedly provided on the top of the fixing ring, a second air nozzle provided on the surface of the rubber sleeve, and a pressure plate forming a pressing structure with the rubber sleeve through a connecting rod.

8. A method for testing the ejection of a corrugated steel pipe reinforced concrete column considering secondary loads, comprising the ejection test apparatus for a corrugated steel pipe reinforced concrete column considering secondary loads as described in claim 1, characterized in that... Includes the following steps: S1: To strengthen the reinforced concrete pier under load, a screw jack is used to apply a preload axial force N1 to the top of the concrete pier. At the same time, a spring is placed at the bottom of the pier to compensate for the creep deformation of the concrete during the load-bearing process, maintain the stability of the preload axial force, eliminate the creep effect, and keep the preload axial force N1 constant. S2: During reinforcement, keep the position of the spiral jack unchanged, attach the corrugated steel pipe to the outside of the concrete pier, place it on the first pad, and use it as a grouting template for grouting; during the push-out test, the four hydraulic jacks under the first pad apply the load simultaneously, and the secondary load force is N2. S3: The force exerted is measured by a force sensor. The relative slippage at the upper end of the new and old interface of the concrete pier is measured by an electronic dial gauge. The relative slippage at the middle, quarter point and lower end of the concrete pier is measured by an embedded electronic slip gauge. The longitudinal and transverse strain of the concrete and the longitudinal strain of the grout are measured by an embedded electronic slip gauge. The strain at the crest, antinode and trough of the corrugated steel pipe is measured by resistance strain gauges: the first strain rosette, the second strain rosette and the third strain rosette. S4: Based on the experimental results, the failure mechanism of the new and old interfaces of corrugated steel pipe reinforced reinforced concrete piers is revealed, the bond-slip constitutive relationship is established, and the influence of existing damage and interface treatment methods on the interface bonding performance of concrete piers is studied.

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