Empty steel pipe axial compression test device for internal local lateral pressurization based on water bag

Abstract

The invention discloses an empty steel pipe axial compression test device for performing internal local lateral pressurization based on a water bag. The empty steel pipe axial compression test device comprises a loading base plate, a pressurization system and a supporting mechanism, the supporting mechanism comprises a square steel pipe, an upper end plate, a lower end plate and a water bag, 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, and the loading base plate is fixed to the upper end plate; steel plate supporting plates are arranged on the four inner side walls of the square steel pipe, water bag separation arc-shaped plates are fixed to the sides, away from the inner side walls of the square steel pipe, of the steel plate supporting plates, the inner side walls of the square steel pipe, the water bag separation arc-shaped plates, the upper end plate and the lower end plate form a pressurization cavity used for containing a water bag, and the water bag is placed in the pressurization cavity. The water bag is connected with the pressurizing system; when the water bag is pressurized, the water bag abuts against the four corner angle parts of the square steel pipe, and a gap is formed between the upper end of the water bag and the upper end plate. According to the invention, experimental data can be obtained more accurately, and verification is provided for theoretical models and numerical simulation.

Description

Technical Field

[0001] The invention relates to a square steel pipe local buckling test device, in particular to an empty steel pipe axial compression test device based on a water bag for performing internal local lateral pressurization. Background Art

[0002] With the rapid economic growth, the construction demand of high-rise and super-high-rise buildings has made steel-concrete composite components the mainstream choice in structural design. Common component forms include steel tube concrete columns and steel plate concrete composite shear walls. While achieving structural lightweight and strengthening, these components also introduce new engineering challenges. In particular, with the application of high-strength concrete and steel, the width-to-thickness ratio of the outer steel plate increases, resulting in an increasingly prominent problem of local buckling of the steel plate. This phenomenon has attracted great attention from the engineering community. In order to meet the requirements of engineering economy, the design of steel-concrete composite components usually requires maximizing the mechanical properties of steel and concrete, especially the yield strength of steel. In terms of structural safety, the local buckling problem of the steel plate may cause premature failure or even overall damage of the component, leading to serious consequences and disasters. Therefore, studying the local buckling problem of the steel plate in the composite structure is crucial to meet the requirements of engineering economy and structural safety.

[0003] At present, the academic community has conducted preliminary research on the local buckling performance of steel tube concrete columns, and the research mainly focuses on theoretical analysis and finite element numerical simulation. However, most existing studies are still at the theoretical stage and lack the support of experimental data. This limitation is mainly due to the lack of specially designed experimental equipment to simulate the local buckling behavior of steel plates in steel tube concrete columns. There are many shortcomings in the existing experimental research methods, such as inaccurate loading methods, failure to fully consider the influence of concrete lateral pressure, and inaccurate simulation of boundary conditions. These problems have seriously restricted the progress of in-depth research on the local buckling performance of steel-concrete composite structures. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above existing technologies and provide an axial compression test device for an empty steel pipe based on a water bag for internal local lateral pressure. This axial compression test device for an empty steel pipe based on a water bag for internal local lateral pressure can accurately obtain experimental data, provide verification for theoretical models and numerical simulations, and thus promote theoretical research on the local buckling performance of steel-concrete composite structures and steel structures.

[0005] The objective of the present invention is achieved through the following technical scheme: the present empty steel pipe axial compression test device based on internal local lateral pressurization by water bag comprises a loading pad, a pressurization system and a supporting mechanism; the supporting mechanism comprises a square steel pipe, an upper end plate, a lower end plate and a water bag, the upper end plate and the lower end plate are respectively arranged at the upper end and the lower end of the square steel pipe, and the loading pad is fixed to the upper end plate; the four inner side walls of the square steel pipe are all provided with a steel plate support plate, and a water bag partition arc plate is fixed on the side of the steel plate support facing away from the inner side wall of the square steel pipe, the inner side wall of the square pipe, the water bag partition arc plate, the upper end plate and the lower end plate form a pressurization chamber for placing the water bag, the water bag is placed in the pressurization chamber, and the water bag is connected to the pressurization system; when the water bag is pressurized, the water bag presses against the four corners of the square steel pipe, and there is a gap between the upper end of the water bag and the upper end plate.

[0006] Preferably, the width of the steel plate support plate is smaller than the width of the inner side wall of the square steel tube, and the steel plate support plate is pressed tightly against the middle of the corresponding inner side wall of the square steel tube.

[0007] Preferably, a water bag cover plate is provided between the water bag and the upper end plate.

[0008] Preferably, the pressurizing system includes a water inlet pipe, a water outlet pipe, a water tank, a variable frequency water pump and a control box, the water inlet pipe and the water outlet pipe are both connected to the water bag, and the water inlet pipe and the water outlet pipe are respectively connected to the water tank through a first pipe and a second pipe, valves are provided on the first pipe and the second pipe, the variable frequency water pump is installed on the first pipe, the variable frequency water pump is located between the water tank and the valve, and the variable frequency water pump is connected to the control box.

[0009] Preferably, the first pipeline is provided with a pressure gauge, the pressure gauge is located between the valve and the water inlet pipe, and the pressure gauge is connected to the control box.

[0010] Preferably, the loading pad includes an upper pad, a lower pad and cross stiffening ribs, the upper pad is connected to the lower pad via the cross stiffening ribs, the lower pad is fixed to the upper end plate, and the pad is provided with grooves matching the water inlet pipe and the water outlet pipe.

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

[0012] The present invention has the following advantages over the prior art:

[0013] 1. The present invention arranges a water bag in a square steel tube, and limits the water bag pressurization area to the corners of the square steel tube through the water bag separation arc plate, so as to study the local buckling performance of steel tube concrete steel plate, that is, to study the stress performance of steel tubes of various materials under the combined action of axial force and lateral forces of different sizes, which is of great significance for promoting research in this field; and the device of the present invention can obtain experimental data more accurately, provide verification for theoretical models and numerical simulations, thereby promoting theoretical research on the local buckling performance of steel-concrete composite structures and steel structures.

[0014] 2. The support mechanism used in the device of the present invention can divide the corner area inside the steel pipe where lateral pressure needs to be applied, so as to adjust the position of the area where the steel plate is subjected to lateral pressure, and provide rigid support for the middle part of the steel pipe to prevent the steel plate from buckling inward.

[0015] 3. The internal support system adopted in the present invention can make the applied axial water pressure independent inside the pressurizing system, which will not affect the axial force of the press during the test, thus saving the trouble of data processing after the test.

[0016] 4. The pressurization system of the present invention adopts a high-precision frequency conversion controller and a frequency conversion water pump. The digital pressure gauge can realize real-time observation and precise control of the internal pressure of the water bag, and realize the adjustable size of the lateral pressure on the steel plate.

[0017] 5. The device of the present invention is used to accurately determine the relationship between the hose pressure and the simulated steel plate transverse stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the internal structure of a support mechanism according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic structural diagram of a support mechanism according to an embodiment of the present invention.

[0020] Figure 3 It is a schematic structural diagram of a loading pad according to an embodiment of the present invention.

[0021] Figure 4 The figure is a schematic diagram of the connection structure between the loading pad and the supporting mechanism according to an embodiment of the present invention.

[0022] Figure 5 It is a structural diagram of an axial compression test device for an empty steel pipe based on a water bag for internal local lateral pressurization according to an embodiment of the present invention.

[0023] Figure 6 FIG. 4 is a cross-sectional view of a square steel tube according to an embodiment of the present invention.

[0024] Among them, 1 is a loading pad, 2 is a pressurizing system, 3 is a supporting mechanism, 4 is a square steel pipe, 5 is an upper end plate, 6 is a lower end plate, 7 is a water bag, 8 is a steel plate supporting plate, 9 is a water bag partition arc plate, 10 is an edge portion, 11 is a pressurizing area, 12 is a non-pressurizing area, 13 is a water bag cover plate, 14 is a water inlet pipe, 15 is a water outlet pipe, 16 is a water tank, 17 is a variable frequency water pump, 18 is a control box, 19 is a first pipeline, 20 is a second pipeline, 21 is a valve, 22 is a pressure gauge, 23 is an upper pad, 24 is a lower pad, 25 is a cross stiffening rib, 26 is a slot, 27 is an upper stiffening rib, and 28 is a lower stiffening rib. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] like Figures 1 to 5 As shown, the present embodiment is an axial compression test device for an empty steel tube for performing local internal lateral pressurization based on a water bag, comprising a loading pad, a pressurizing system and a supporting mechanism; the supporting mechanism comprises a square steel tube, an upper end plate, a lower end plate and a water bag, the upper end plate and the lower end plate are respectively arranged at the upper end and the lower end of the square steel tube, and the loading pad is fixed to the upper end plate; the four inner side walls of the square steel tube are all provided with a steel plate support plate, and a water bag partition arc plate is fixed on the side of the steel plate support facing away from the inner side wall of the square steel tube, the inner side wall of the square tube, the water bag partition arc plate, the upper end plate and the lower end plate form a pressurizing chamber for placing the water bag, the water bag is placed in the pressurizing chamber, and the water bag is connected to the pressurizing system; when the water bag is pressurized, the water bag presses against the four corners of the square steel tube, and there is a gap between the upper end of the water bag and the upper end plate.

[0027] Specifically, the present invention sets the water bag separation arc plate in the inner cavity of the square steel tube through the steel plate support plate to separate the inner cavity of the square steel tube into the pressurized area and the non-pressurized area of ​​the water bag. In order to further ensure the accuracy of the test results, the lower end of the water bag separation arc plate is welded and fixed to the lower end plate; at the same time, a water bag cover plate is provided between the water bag and the upper end plate to prevent the upper end of the water bag from hitting the upper end plate after the water bag is filled with water and pressurized, so as to ensure that the upper end plate will not press the internal support system formed by the water bag during the axial compression test.

[0028] The width of the steel plate support plate is smaller than the width of the inner side wall of the square steel pipe, and the steel plate support plate is pressed against the middle of the corresponding inner side wall of the square steel pipe. This arrangement is simple, and the four corner pressurization areas separated by the water bag separation arc plate have the same shape, ensuring that the water bag uniformly pressurizes the four corners of the square steel pipe, thereby further improving the accuracy of the test.

[0029] The pressurization system includes an inlet pipe, an outlet pipe, a water tank, a variable frequency water pump and a control box. The inlet pipe and the outlet pipe are both connected to the water bag, and the inlet pipe and the outlet pipe are respectively connected to the water tank through a first pipe and a second pipe. The first pipe and the second pipe are both provided with valves. The variable frequency water pump is installed in the first pipe, and the variable frequency water pump is located between the water tank and the valve. The variable frequency water pump is connected to the control box. The first pipe is provided with a pressure gauge, and the pressure gauge is located between the valve and the inlet pipe, and the pressure gauge is connected to the control box. Specifically, the water tank → high-precision variable frequency water pump → pressure gauge → inlet pipe → water bag → outlet pipe → water tank constitutes a water circulation pressurization system. At the same time, the pressure gauge is installed in front of the water inlet pipe, and the water pressure inside the water bag is precisely controlled in cooperation with the variable frequency control box to further improve the accuracy of the test results. The variable frequency water pump adopts the high-precision variable frequency water pump CDLF2-260, the control box adopts the variable frequency control box SCKB1-3, the first pipeline and the second pipeline both adopt DN25 connecting water pipes, and the pressure gauge adopts a digital pressure gauge.

[0030] The loading pad includes an upper pad, a lower pad and cross stiffening ribs, the upper pad is connected to the lower pad via the cross stiffening ribs, the lower pad is fixed to the upper end plate, and the pad is provided with slots matching the water inlet pipe and the water outlet pipe. The loading pad of this structure is simple in structure and easy to install, and the slot setting facilitates the passage of the water inlet pipe and the water outlet pipe, making the overall structure of the device compact.

[0031] An upper stiffening rib is fixed between the upper end plate and the square steel tube, and a lower stiffening rib is fixed between the lower end plate and the square steel tube. The upper stiffening rib and the lower stiffening rib further ensure the firmness of the upper end plate and the lower end plate of the square steel tube, respectively, and ensure the effective conduct of the test. At the same time, the upper stiffening rib can also strengthen the area of ​​the square steel tube that is not supported by the steel plate support plate, and prevent local buckling of the end of the square steel tube.

[0032] After the present invention sets the water pressure setting value through the frequency conversion control box, the high-precision frequency conversion water pump starts working to transport the water in the water tank to the water bag. After the water bag expands, due to the limitation of the water bag separation arc plate and the water bag cover plate, the water pressure will be transmitted to the corners of the steel pipe column, forming a local pressurization of the steel pipe column. During the pressurization process, the digital pressure gauge will feed back the water pressure to the frequency conversion control box in real time. When the water pressure reaches the set value, the frequency conversion control box will automatically turn off the high-precision frequency conversion water pump to prevent excessive pressure; at the same time, when the pressure is lower than the set value, the frequency conversion control box will automatically start the frequency conversion water pump to start pressurization. During pressurization, since the water bag cover plate fixes the inlet and outlet water pipes, the upward force brought by the water pressure on the top of the water bag is limited to the internal support system. During the axial compression process, due to the action of the steel plate support plate, the steel plate can only bulge outward.

[0033] It should be noted that when using water bags for local pressurization to simulate the lateral extrusion force on the steel pipe wall at the corner, the amount of water pressure must be calculated and determined in advance. Figure 6 As shown in the figure, since there are stiffening ribs on both the top and bottom, the square steel plate in the middle area with a height of y and a thickness of t is considered; the width of the corner area separated by the arc plate is x, and the pressure of the added water pressure is P, then the relationship between the water pressure P and the transverse stress σ in the middle of the steel plate is as follows:

[0034] F=P·(x·y)

[0035]

[0036] The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. An axial compression test device for an empty steel pipe based on a water bag for internal local lateral pressurization, characterized in that: It includes a loading pad, a pressurizing system and a supporting mechanism; the supporting mechanism includes a square steel tube, an upper end plate, a lower end plate and a water bag, the upper end plate and the lower end plate are respectively arranged at the upper end and the lower end of the square steel tube, and the loading pad is fixed to the upper end plate; the four inner walls of the square steel tube are each provided with a steel plate support plate, and a water bag separating arc plate is fixed on the side of the steel plate support facing away from the inner wall of the square steel tube, the inner wall of the square tube, the water bag separating arc plate, the upper end plate and the lower end plate form a pressurizing chamber for placing the water bag, the water bag is placed in the pressurizing chamber, and the water bag is connected to the pressurizing system; when the water bag is pressurized, the water bag presses against the four corners of the square steel tube, and there is a gap between the upper end of the water bag and the upper end plate.

2. The empty steel pipe axial compression test device based on water bag for internal local lateral pressurization according to claim 1 is characterized in that: The width of the steel plate support plate is smaller than the width of the inner side wall of the square steel pipe, and the steel plate support plate is pressed tightly against the middle of the corresponding inner side wall of the square steel pipe.

3. The empty steel pipe axial compression test device based on water bag for internal local lateral pressurization according to claim 1 is characterized in that: A water bag cover plate is arranged between the water bag and the upper end plate.

4. The empty steel pipe axial compression test device based on water bag for internal local lateral pressurization according to claim 1 is characterized in that: The pressurizing system includes a water inlet pipe, a water outlet pipe, a water tank, a variable frequency water pump and a control box. The water inlet pipe and the water outlet pipe are both connected to the water bag, and the water inlet pipe and the water outlet pipe are respectively connected to the water tank through a first pipe and a second pipe. Valves are provided on the first pipe and the second pipe. The variable frequency water pump is installed on the first pipe. The variable frequency water pump is located between the water tank and the valve. The variable frequency water pump is connected to the control box.

5. The empty steel pipe axial compression test device based on water bag for internal local lateral pressurization according to claim 4 is characterized in that: The first pipeline is provided with a pressure gauge, which is located between the valve and the water inlet pipe, and the pressure gauge is connected to the control box.

6. The empty steel pipe axial compression test device based on internal local lateral pressurization by a water bag according to claim 4 is characterized in that: The loading pad includes an upper pad, a lower pad and cross stiffening ribs, the upper pad is connected to the lower pad via the cross stiffening ribs, the lower pad is fixed to the upper end plate, and the pad is provided with grooves matching the water inlet pipe and the water outlet pipe.

7. The empty steel pipe axial compression test device based on water bag for internal local lateral pressurization according to claim 1 is 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.

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