Hollow steel pipe axial compression test device with internal local lateral compression

Abstract

The utility model discloses an empty steel pipe axial compression test device with internal local lateral pressurization. The empty steel pipe axial compression test device comprises an upper loading head, a lower loading head, a pressurization system, a fire hose and a supporting mechanism, the supporting mechanism comprises a square steel pipe, an upper end plate and a lower end plate, the upper end plate and the lower end plate are arranged at the upper end and the lower end of the square steel pipe respectively, the upper loading head and the lower loading head are installed on the upper end plate and the lower end plate respectively, middle steel channels are arranged on the four inner side walls of the square steel pipe respectively, and corner arc plates are arranged on the four corner angles of the square steel pipe respectively. The corner arc plate and the square steel pipe form a pressurization channel, the two ends of the fire hose are connected with an outlet and an inlet of the pressurization system respectively, and one end of the fire hose penetrates through one end of the pressurization channel and extends out of the other end of the pressurization channel. Supporting rods are connected between every two opposite middle grooves and between every two opposite corner arc plates. According to the utility model, experimental data can be obtained more accurately, and verification is provided for theoretical models and numerical simulation.

Description

TECHNICAL FIELD

[0001] The utility model relates to steel pipe local buckling test, concretely relates to a kind of empty steel pipe axial compression test device of internal local lateral pressurization. BACKGROUND

[0002] In recent years, the advantage of steel-concrete composite structure in mechanical property and seismic energy dissipation capacity is more and more obvious, and they are more and more widely used in high-rise and super high-rise buildings. Common component forms include steel pipe concrete column and steel plate concrete composite shear wall, etc., among which the steel pipe concrete column has been most widely used in practical engineering. Domestic and foreign scholars have carried out theoretical and experimental research on the bearing capacity and local buckling of steel pipe concrete columns with different cross-sectional forms. Nowadays, with the gradual application of high-strength steel and high-strength concrete, the cross-sectional size of the component has also changed, such as the decrease of steel pipe wall thickness and the increase of width. These changes lead to the increase of width-thickness ratio of the steel plate outside the steel pipe concrete, making the steel plate local buckling problem more and more significant, which becomes the focus of engineering and technical personnel. In terms of engineering economy, the design of steel-concrete composite component usually requires to maximize the mechanical properties of steel and concrete, especially the yield strength of steel. In terms of structural safety, the local buckling problem of steel plate may cause premature failure of component and even overall damage, leading to serious consequences and disasters. Therefore, the research on the local buckling problem of steel plate in composite structure is crucial to meet the requirements of engineering economy and structural safety.

[0003] At present, domestic and foreign scholars have begun to pay attention to the local buckling performance of steel plate in steel pipe concrete column, and the research mainly focuses on theoretical analysis and finite element numerical simulation. However, most of the existing researches still remain at the theoretical stage, lacking experimental data support, making it difficult to verify the theoretical model and numerical model through experimental data, thus limiting the further research of theory. This is mainly due to the lack of experimental devices specially designed for the local buckling performance of steel pipe concrete and steel plate at home and abroad, making it difficult for researchers to carry out related experiments and obtain sufficient variable parameter test data to support and improve theoretical research, which restricts the research progress of steel-concrete composite structure and steel structure local buckling performance. UTILITY MODEL CONTENT

[0004] The utility model aims at overcoming the deficiencies of the prior art, and provides an empty steel pipe axial compression test device for internal local lateral pressurization. This internal local lateral pressurization empty steel pipe axial compression test device can simulate the uneven lateral extrusion force of the internal filling concrete on the outer steel pipe wall in steel pipe concrete, with larger lateral pressure at the corner and smaller lateral pressure in the middle, accurate test results, and provides reliable basis for the theoretical research of local buckling performance.

[0005] The utility model discloses a purpose is realized through following technical scheme: this inside partial lateral pressurization's empty steel pipe axial pressure test device, including upper loading head, lower loading head, pressurization system, fire hose and support mechanism, the support mechanism includes square steel pipe, upper end plate and lower end plate, the upper end plate and lower end plate are arranged at the upper end and the lower end of square steel pipe respectively, the upper loading head and lower loading head are installed on the upper end plate and lower end plate respectively, four inner side walls of square steel pipe all are provided with middle channel steel, four corner parts of square steel pipe all are equipped with corner arc plate, and this corner arc plate and square steel pipe form pressurization passage, the both ends of fire hose are connected with the export and import of pressurization system respectively, and one end of fire hose passes through one end of pressurization passage and extends from the other end of pressurization passage, and the support rod is connected between the two opposite middle channel and the two opposite corner arc plate.

[0006] Preferably, the lower end of the corner arc plate is welded and fixed with the lower end plate, and the upper end of the corner arc plate has a spacing with the upper end plate.

[0007] Preferably, the pressurization system comprises a water tank, a variable frequency water pump, a variable frequency control box, a pressure gauge, a first water pipe and a second water pipe, one end of the first water pipe is connected with the outlet of the water tank, the other end of the first water pipe is connected with the other end of the fire hose through a first water hose joint, one end of the second water pipe is connected with the inlet of the water tank, the other end of the second water pipe is connected with one end of the fire hose through a second water hose joint, the first water pipe and the second water pipe are both provided with valves, the variable frequency water pump and the pressure gauge are both installed on the first water pipe, and the variable frequency water pump, the valve located on the first water pipe and the pressure gauge are sequentially distributed along the water flow direction of the first water pipe, and the variable frequency water pump and the pressure gauge are both connected with the variable frequency control box.

[0008] Preferably, the first water hose joint is connected with the other end of the fire hose through a water hose clamp, and the second water hose joint is connected with one end of the fire hose through a water hose clamp.

[0009] Preferably, the internal partial lateral pressurization's empty steel pipe axial pressure test device further comprises a support column, a first branch pipe and a second branch pipe, the first water pipe is connected with the first water hose joint through the first branch pipe, the second branch pipe is fixed to the upper end of the support column, and the second water pipe is connected with the second water hose joint through the second branch pipe.

[0010] Preferably, the support rods connected between the two opposite middle channel have multiple, and are uniformly distributed from top to bottom; the support rods connected between the two opposite corner arc plates have multiple, and are uniformly distributed from top to bottom.

[0011] Preferably, an upper stiffening rib is fixed between the upper end plate and the square steel pipe, and a lower stiffening rib is fixed between the lower end plate and the square steel pipe.

[0012] Preferably, the upper loading head comprises a first cross stiffening rib, a first upper pad plate and a second upper pad plate, the first upper pad plate and the second upper pad plate are connected through the first cross stiffening rib, the first upper pad plate is fixed with the upper end plate, and the first upper pad plate is provided with a first opening.

[0013] Preferably, the lower loading head comprises a second cross stiffening rib, a first lower pad plate and a second lower pad plate, the first lower pad plate and the second lower pad plate are connected through the second cross stiffening rib, the first lower pad plate is fixed with the lower end plate, and the first lower pad plate is provided with a second opening.

[0014] The utility model discloses relative to prior art has the following advantages:

[0015] 1, the utility model discloses can accurate simulation steel pipe concrete in the uneven lateral extrusion of the concrete filled in the outer steel pipe wall, the lateral pressure of corner portion is bigger, and the lateral pressure of middle part is smaller, is applicable to the research of the stress performance of steel pipe of various materials under the joint action of axial force and different size lateral force, accurate, provides reliable basis for the theoretical research of local buckling performance.

[0016] 2, the utility model discloses utilize square steel sheet and corner portion arc plate to constitute pressurizing passage, and then utilize fire hose to load pressure in pressurizing passage, which initiatively carries out water injection pressurization to fire hose, and then applies lateral pressure to the corner portion of steel pipe column, and further improves the accuracy of test.

[0017] 3, the utility model discloses support mechanism mainly comprises square steel pipe, upper end plate, lower end plate, middle channel steel and corner portion arc plate, etc., and this support mechanism independently adds axial water pressure in the pressurizing system, and when testing, the axial force size of the press is not influenced, and the trouble of data processing after testing is saved. Meanwhile, the support mechanism can segment the corner portion area needing to apply lateral pressure in the steel pipe, realizes the adjustable position of the area of steel sheet under lateral pressure, and provides rigid support to the middle part of steel pipe and prevents the inward buckling of steel sheet.

[0018] 4, the utility model discloses that pressurizing system adopts high-precision frequency conversion controller and frequency conversion water pump, and the real-time observation and accurate control of the pressure in water bag can be realized by digital display pressure gauge, and the adjustable size of lateral pressure of steel sheet is realized.

[0019] 5, the utility model discloses can accurately give the relationship between fire hose and the simulated steel sheet transverse stress, and provides reliable theoretical basis for the research of steel-concrete composite structure and steel structure local buckling performance. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the internal structure diagram of square steel pipe in the utility model.

[0021] Figure 2 is a structure diagram of the support mechanism in the embodiment of the utility model.

[0022] Figure 3 is a connection structure diagram between the second water hose joint and the second water pipe in the embodiment of the utility model.

[0023] Figure 4 is a structure diagram of the upper loading head in the embodiment of the utility model.

[0024] Figure 5 is a first structure diagram of the lower loading head in the embodiment of the utility model.

[0025] Figure 6 is a second structure diagram of the lower loading head in the embodiment of the utility model.

[0026] Figure 7 is a connection structure diagram between the upper and lower loading heads and the support mechanism in the embodiment of the utility model.

[0027] Figure 8 is the internal partial lateral pressure steel pipe axial test device in the embodiment of the utility model.

[0028] Figure 9 is a sectional view of the support mechanism in the embodiment of the utility model.

[0029] In the figure, 1 is the upper loading head, 2 is the lower loading head, 3 is the pressure system, 4 is the fire hose, 5 is the support mechanism, 6 is the square steel pipe, 7 is the upper end plate, 8 is the lower end plate, 9 is the middle channel steel, 10 is the corner arc plate, 11 is the pressure channel, 12 is the support rod, 13 is the water tank, 14 is the frequency conversion water pump, 15 is the frequency conversion control box, 16 is the pressure gauge, 17 is the first water pipe, 18 is the second water pipe, 19 is the first water hose joint, 20 is the second water hose joint, 21 is the water hose clamp, 22 is the support column, 23 is the first branch pipe, 24 is the second branch pipe, 25 is the upper stiffening rib, 26 is the lower stiffening rib, 27 is the first cross stiffening rib, 28 is the first upper pad plate, 29 is the second upper pad plate, 30 is the first hole, 31 is the second cross stiffening rib, 32 is the first lower pad plate, 33 is the second lower pad plate, 34 is the second hole, and 35 is the valve. DETAILED DESCRIPTION

[0030] The utility model will be further described below in combination with the drawings and embodiments.

[0031] For example, Figures 1 to 9The internal partial lateral pressure steel pipe axial test device shown includes an upper loading head, a lower loading head, a pressure system, a fire hose and a support mechanism; the support mechanism includes a square steel pipe, an upper end plate and a lower end plate, the upper end plate and the lower end plate are arranged at the upper end and the lower end of the square steel pipe respectively, the upper loading head and the lower loading head are installed on the upper end plate and the lower end plate respectively, the four inner side walls of the square steel pipe are provided with middle channel steels, and the four corner portions of the square steel pipe are provided with corner arc plates, the corner arc plates and the square steel pipe form a pressure channel, the two ends of the fire hose are connected with the outlet and the inlet of the pressure system respectively, and one end of the fire hose passes through one end of the pressure channel and extends out of the other end of the pressure channel; support rods are connected between the two opposite middle channel steels and the two opposite corner arc plates.

[0032] Specifically, four corner arc plates are arranged at the four corner portions of the square steel pipe to form four pressure channels for placing the fire hose, and the two opposite corner arc plates are connected by the support rods; and four middle channel steels are fixed on the four inner side walls of the square steel pipe, and the middle channel steels are located in the middle of the corresponding inner side walls, and the two opposite middle channel steels are connected by the support rods. The support rods connected between the two opposite middle channel steels have multiple and are uniformly distributed from top to bottom; the support rods connected between the two opposite corner arc plates have multiple and are uniformly distributed from top to bottom. The corner arc plates arranged in this way constitute a stable support for the fire hose, and the force generated by the expansion of the fire hose acts on the corner portions of the square steel pipe to form a corner side pressure. Further, the pressure channel formed in this way applies pressure to the corner portions, applies a bidirectional stress state to the middle portion of the outer steel plate in the axial test, avoids additional second-order effects caused by the lateral pressure of the water pressure on the steel plate, and is more consistent with the stress state of the outer steel pipe of the concrete-filled steel tube column and the steel plate concrete shear wall, which helps to analyze the local buckling performance of the outer steel plate in the concrete-filled steel tube column and the steel plate concrete shear wall under the axial compression state and avoid interference of the out-of-plane lateral pressure on the local buckling. The middle channel steel constitutes a stable support structure for the square steel pipe, simulates the rigid medium effect of the concrete, prevents the steel plate from occurring inward local buckling, and thus improves the accuracy of the test results.

[0033] The lower end of the corner arc plate is welded and fixed with the lower end plate, and the upper end of the corner arc plate has a spacing with the upper end plate. In this way, when the fire hose is filled with water for pressure loading, the upper end will not be pressed against the upper end plate, so as to ensure that the upper end plate will not press against the internal support system of the square steel pipe during the axial test.

[0034] As Figure 8As shown, the pressurizing system comprises a water tank, a variable frequency water pump, a variable frequency control box, a pressure gauge, a first water pipe and a second water pipe, one end of the first water pipe is connected with the outlet of the water tank, the other end of the first water pipe is connected with the other end of the fire hose through a first water hose joint, one end of the second water pipe is connected with the inlet of the water tank, the other end of the second water pipe is connected with one end of the fire hose through a second water hose joint; the first water pipe and the second water pipe are both provided with valves, the variable frequency water pump and the pressure gauge are both installed on the first water pipe, and the variable frequency water pump, the valve located on the first water pipe and the pressure gauge are sequentially distributed along the water flow direction of the first water pipe, the variable frequency water pump and the pressure gauge are both connected with the variable frequency control box. The variable frequency water pump adopts a high-precision variable frequency water pump CDLF2-260, the control box adopts a variable frequency control box SCKB1-3, the first water pipe and the second water pipe both adopt DN25 connecting water pipes, and the pressure gauge adopts a digital pressure gauge. At the same time, the two ends of the fire hose are connected with the first water pipe and the second water pipe through the first water hose joint and the second water hose joint respectively, which facilitates the replacement of the fire hose and ensures the effective performance of the test. And in the whole system, the water flow sequentially passes through the water tank→the high-precision variable frequency water pump→the digital pressure gauge→the water hose joint→the fire hose→the water hose joint→the water tank, so that the internal water pressure of the fire hose is accurately controlled by the variable frequency control box, so as to ensure the working effect of the pressurizing system and provide sufficient water pressure for the fire hose.

[0035] The first water hose joint is connected with the other end of the fire hose through a water hose clamp, and the second water hose joint is connected with one end of the fire hose through a water hose clamp. The water hose clamp is used to further facilitate the installation of the device and the replacement of the fire hose.

[0036] The internal partial lateral pressurizing steel pipe axial compression test device further comprises a support column, a first branch pipe and a second branch pipe, the first water pipe is connected with the first water hose joint through the first branch pipe, the second branch pipe is fixed to the upper end of the support column, and the second water pipe is connected with the second water hose joint through the second branch pipe. This structure is simple and facilitates the installation of the second water hose joint, and avoids the influence of water pressure on the measurement of the axial bearing capacity of the steel pipe.

[0037] An upper stiffening rib is fixed between the upper end plate and the square steel pipe, and a lower stiffening rib is fixed between the lower end plate and the square steel pipe. The upper stiffening rib and the lower stiffening rib further ensure the firmness of the square steel pipe with respect to the upper end plate and the lower end plate respectively, and ensure the effective performance of the test. At the same time, the upper stiffening rib can also strengthen the area of the square steel pipe supported by the steel plate support plate, and prevent local buckling of the end of the square steel pipe.

[0038] As Figures 4 to 6As shown, the upper loading head comprises a first cross stiffening rib, a first upper backing plate and a second upper backing plate, the first upper backing plate and the second upper backing plate are connected through the first cross stiffening rib, the first upper backing plate is fixed with the upper end plate, and the first upper backing plate is provided with a first opening. The lower loading head comprises a second cross stiffening rib, a first lower backing plate and a second lower backing plate, the first lower backing plate and the second lower backing plate are connected through the second cross stiffening rib, the first lower backing plate is fixed with the lower end plate, and the first lower backing plate is provided with a second opening. The upper loading head and the lower loading head in the embodiment have the same structure, and are only different in installation position and are mirror-symmetrically arranged. The arrangement of the loading head can limit the application of the pressurizing system to the square steel pipe, prevent the fire hose from being excessively stretched longitudinally to cause rupture, and also avoid the influence of water pressure on the measurement of the axial bearing capacity of the steel pipe. Meanwhile, the first upper backing plate is provided with four first openings, and the first lower backing plate is provided with four second openings, the four first openings and the four second openings correspond to the pressurizing channels in the square steel pipe, so that the installation of the first hose joint and the second hose joint is facilitated.

[0039] After the water pressure setting value is set by the frequency conversion control box, the high-precision frequency conversion water pump starts to work to deliver the water in the water tank to the fire hose. After the fire hose is inflated, the water pressure is transmitted to the square steel pipe due to the limitation of the corner arc plate, so that the local pressurization of the square steel pipe is formed. During the pressurization, the pressure gauge feeds back the water pressure to the frequency conversion control box in real time, and when the water pressure reaches the setting value, the frequency conversion control box automatically closes the high-precision frequency conversion water pump to prevent the pressure from being too large; meanwhile, when the pressure is lower than the setting value, the frequency conversion control box automatically starts the frequency conversion water pump to start pressurization. During the pressurization, the water pipe is fixed by the loading head and the like, so that the upward force caused by the water pressure at the top of the hose does not act on the hose itself to cause the axial stretching of the hose. During the axial pressurization, the steel plate can only be bent outward due to the support of the middle channel steel.

[0040] For using the local pressurization of the fire hose to simulate the lateral extrusion force received by the corner outer steel pipe wall, the size of the water pressure to be applied needs to be determined in advance. Taking the test piece in the Figure 9 For using the local pressurization of the fire hose to simulate the lateral extrusion force received by the corner outer steel pipe wall, the size of the water pressure to be applied needs to be determined in advance. Taking the test piece in the

[0041] F=P·(x·y)

[0042]

[0043] The above specific embodiments are preferred embodiments of the utility model, and cannot limit the utility model, and any change or other equivalent replacement mode without departing from the technical scheme of the utility model is included in the protection scope of the utility model.

Claims

1. An axial compression testing device for hollow steel pipes with internal localized lateral pressure, characterized in that, The system includes an upper loading head, a lower loading head, a pressurization system, a fire hose, and a support mechanism. The support mechanism includes a square steel pipe, an upper end plate, and a lower end plate. The upper end plate and the lower end plate are respectively located at the upper and lower ends of the square steel pipe. The upper loading head and the lower loading head are respectively installed on the upper end plate and the lower end plate. The four inner side walls of the square steel pipe are provided with central channel steel, and the four corners of the square steel pipe are provided with corner arc plates. These corner arc plates and the square steel pipe form a pressurization channel. The two ends of the fire hose are respectively connected to the outlet and inlet of the pressurization system, and one end of the fire hose passes through one end of the pressurization channel and extends out to the other end of the pressurization channel. Support rods are connected between the two opposite central grooves and between the two opposite corner arc plates.

2. The axial compression testing device for hollow steel pipe with internal local lateral pressurization according to claim 1, characterized in that, The lower end of the corner arc plate is welded and fixed to the lower end plate, and there is a gap between the upper end of the corner arc plate and the upper end plate.

3. The axial compression testing device for an empty steel pipe with internal local lateral pressurization according to claim 1, characterized in that, The pressurization system includes a water tank, a variable frequency water pump, a variable frequency control box, a pressure gauge, a first water pipe, and a second water pipe. One end of the first water pipe is connected to the outlet of the water tank, and the other end of the first water pipe is connected to the other end of a fire hose through a first hose connector. One end of the second water pipe is connected to the inlet of the water tank, and the other end of the second water pipe is connected to the one end of a fire hose through a second hose connector. Both the first and second water pipes are equipped with valves. The variable frequency water pump and the pressure gauge are both installed on the first water pipe, and the variable frequency water pump, the valves located on the first water pipe, and the pressure gauge are distributed sequentially along the water flow direction in the first water pipe. The variable frequency water pump and the pressure gauge are both connected to the variable frequency control box.

4. The axial compression testing device for an empty steel pipe with internal local lateral pressurization according to claim 3, characterized in that, The first hose connector is connected to the other end of the fire hose via a hose clamp, and the second hose connector is connected to one end of the fire hose via a hose clamp.

5. The axial compression testing device for hollow steel pipe with internal local lateral pressurization according to claim 3, characterized in that, It also includes a support column, a first branch pipe and a second branch pipe. The first water pipe is connected to the first water hose connector through the first branch pipe. The second branch pipe is fixed to the upper end of the support column. The second water pipe is connected to the second water hose connector through the second branch pipe.

6. The axial compression testing device for an empty steel pipe with internal local lateral pressurization according to claim 1, characterized in that, There are multiple support rods connecting the two opposite central grooves, which are evenly distributed from top to bottom; there are also multiple support rods connecting the two opposite corner arc plates, which are evenly distributed from top to bottom.

7. The axial compression testing device for an empty steel pipe with internal local lateral pressure according to claim 1, characterized in that, An upper stiffening rib is fixed between the upper end plate and the square steel pipe, and a lower stiffening rib is fixed between the lower end plate and the square steel pipe.

8. The axial compression testing device for an empty steel pipe with internal local lateral pressure according to claim 7, characterized in that, The upper loading head includes a first cross stiffening rib, a first upper pad and a second upper pad. The first upper pad and the second upper pad are connected by the first cross stiffening rib. The first upper pad is fixed to the upper end plate and has a first opening.

9. The axial compression testing device for hollow steel pipe with internal local lateral pressurization according to claim 1, characterized in that, The lower loading head includes a second cross stiffening rib, a first lower pad and a second lower pad. The first lower pad and the second lower pad are connected by the second cross stiffening rib. The first lower pad is fixed to the lower end plate and has a second opening.

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