Axial compression test device and test method for steel pipe column subjected to internal local lateral pressure

Abstract

The present invention discloses an axial compression test device and a test method for a steel pipe column subjected to internal local lateral pressure, comprising a local pressurizing component, a steel pipe column, a regional separation support component, a loading component, a bottom plate, a cover plate and a filling bag; the bottoms of the steel pipe column and the regional separation support component are both connected to the bottom plate, the regional separation support component is located in the steel pipe column, the regional separation support component abuts against the middle area of ​​the inner wall of the steel pipe column, and divides the space in the steel pipe column into a plurality of edge areas, a filling bag is placed in each edge area, the top of the steel pipe column is connected to the cover plate, the top surface of the cover plate is connected to the loading component, an external axial loading device applies an axial force to the loading component, the loading component and the cover plate are respectively provided with injection holes, an injection pipe is connected to the filling bag through the injection hole, the local pressurizing component is connected to the injection pipe, the local pressurizing component injects filler into the filling bag through the injection pipe, so that the filling bag expands and abuts against the edge area in the steel pipe column, so as to provide lateral pressure for the steel pipe column.

Description

Technical Field

[0001] The invention relates to the technical field of steel pipe column buckling performance testing, and in particular to an axial compression testing device and a testing method for a steel pipe column subjected to internal local lateral pressure. Background Art

[0002] In recent years, steel-concrete composite structures have been widely used in high-rise and super-high-rise buildings due to their superior mechanical properties and seismic energy absorption capacity. Typical component forms include steel tube concrete columns and steel plate concrete composite shear walls, among which steel tube concrete columns are the most widely used in engineering. Domestic and foreign scholars have conducted corresponding theoretical and experimental studies on the bearing capacity of steel tube concrete columns with various cross-sectional forms. Nowadays, high-strength steel and high-strength concrete have also begun to be used in steel tube concrete structures. However, the emergence of high-strength materials will inevitably bring about changes in the cross-sectional size of components, such as reduced steel tube wall thickness and increased width. These changes have made the width-to-thickness ratio of the steel plate on the outside of the steel tube concrete increasingly larger, and the problem of local buckling of the steel plate has become increasingly prominent, and has begun to attract the attention of engineering personnel. In terms of engineering economy, steel-concrete composite components generally require that the mechanical properties of both steel and concrete materials can be fully utilized during the design process, and steel must be able to fully utilize its yield strength. In terms of structural safety, the emergence of local buckling of steel plates will cause premature damage to components or even overall failure, causing irreparable losses and disasters. Therefore, in the context of engineering economy and structural safety, it is necessary to study the local buckling of composite structural steel plates. In-depth research on the local buckling characteristics and buckling modes of steel plates and taking targeted measures to avoid or delay the occurrence of local buckling of steel plates can not only produce good economic benefits, but also have important significance for promoting the development and application of steel-concrete composite structures and thin-walled steel structures in engineering.

[0003] Nowadays, scholars at home and abroad have begun to study the local buckling performance of steel plates in steel tube concrete columns. The main research methods are limited to theoretical research and finite element numerical research, and certain research results have been achieved. However, in these existing studies, they are basically limited to the theoretical stage and lack experimental research results for demonstration. The theoretical model and numerical model proposed by the researchers cannot be verified with the experimental data, and the theoretical research cannot be further improved. The reason is that there is a lack of special experimental equipment for studying the local buckling performance of steel tube concrete and steel plates at home and abroad. This problem makes it difficult for researchers to carry out relevant experimental research when studying the local buckling performance of steel tubes, and it is impossible to obtain sufficient variable parameter test results to support and improve the theory, which directly restricts the research progress of steel-concrete composite structures and local buckling performance of steel structures.

[0004] Therefore, it is very necessary to develop a targeted test device for the local buckling performance of steel tube concrete-filled steel plates. Studies have found that the lateral extrusion of the outer steel tube of the steel tube concrete-filled steel tube by the inner filling concrete is uneven in the transverse direction. The steel tube in the edge area is subjected to a larger lateral extrusion pressure from the concrete, while the lateral extrusion pressure in the middle is smaller. In addition, different width-to-thickness ratios, steel strengths, and concrete strengths have different extrusion effects on the steel tube, and the local buckling performance of the steel tube is also affected differently by the lateral force. Therefore, the device needs to be able to simulate the uneven lateral extrusion effect of the inner filling concrete on the outer steel tube wall in the steel tube concrete-filled steel tube, with large lateral pressure in the corners and small lateral pressure in the middle. The range and size of the lateral pressure need to be adjustable to study the local buckling process of the steel plate subjected to local lateral pressure in different areas and the influence of lateral pressures of different sizes on the local buckling performance of the steel plate. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide an axial compression test device for a steel pipe column subjected to an internal local lateral pressure, which can simulate the uneven lateral squeezing effect of the steel pipe column on the steel pipe column by the concrete filled in the steel pipe column.

[0006] Another object of the present invention is to provide a testing method for the above-mentioned steel pipe column axial compression testing device subjected to internal local lateral pressure.

[0007] The technical solution of the present invention is: an axial compression test device for a steel pipe column subjected to an internal local lateral pressure, comprising a local pressurizing component, a steel pipe column, a regional separation support component, a loading component, a bottom plate, a cover plate, a filling bag and an injection pipe;

[0008] The bottoms of the steel pipe column and the area separation support assembly are both connected to the bottom plate. The area separation support assembly is located inside the steel pipe column. The area separation support assembly abuts the middle area of ​​the inner wall of the steel pipe column and divides the space inside the steel pipe column into multiple edge areas. A filling bag is placed in each edge area. The top of the steel pipe column is connected to the cover plate. The top surface of the cover plate is connected to the loading assembly. The external axial loading device is used to apply axial force to the loading assembly. The loading assembly and the cover plate are respectively provided with injection holes. The injection pipe is connected to the filling bag through the injection hole. The local pressurizing assembly is connected to the injection pipe. The local pressurizing assembly is used to inject filler into the filling bag through the injection pipe, so that the filling bag expands and abuts the edge area inside the steel pipe column. The filling bag is used to provide lateral pressure for the steel pipe column. The area separation support assembly of the present invention is used to support the steel pipe column during the test, simulating the rigid medium effect of concrete to prevent the steel pipe column from locally buckling inward. At the same time, it has the function of area separation, which can separate the middle area and edge area of ​​each side of the steel pipe column, provide loading space and partition for applying different loads, and control the pressure of the filling bag by adjusting the amount of filler, so as to adjust the lateral pressure on the steel pipe column.

[0009] Furthermore, the filling bag is a water bag, and the local pressurization component includes a water tank, a variable frequency water pump, a high-precision variable frequency control box and a connecting pipe. The water tank is connected to the injection pipe through the connecting pipe, and the variable frequency water pump is connected between the water tank and the connecting pipe. The connecting pipe is provided with a digital pressure gauge and a flow valve. The digital pressure gauge is used to check the water pressure in the connecting pipe. The variable frequency water pump is electrically connected to the high-precision variable frequency control box. By filling the filling bag with water to perform local pressurization, the cost is low, the safety factor is high, and the operation is easy.

[0010] Furthermore, the area separation support assembly includes multiple support steel plates, multiple transverse support ribs and multiple separation steel plates. The support steel plates are close to the middle area of ​​the inner wall of the steel pipe column. The two ends of the transverse support ribs are respectively connected to two opposite support steel plates. The two sides of the support steel plates are respectively connected to the separation steel plates. One side of the separation steel plate is connected to the side of the support steel plate, and the other side is connected to the transverse support ribs. An edge area is formed between the separation steel plates on two adjacent support steel plates. The area separation support assembly of the present invention has a simple structure and is convenient for device connection through pre-welding.

[0011] Furthermore, the partition steel plates on both sides of the support steel plate and the support steel plate are arranged together to form a triangle, so as to enhance the structural strength of the regional partition support assembly, enhance the force bearing capacity, and strengthen the support for the steel pipe column.

[0012] Furthermore, the loading assembly includes an upper pad, a lower pad and a stiffening rib, the lower pad is connected to the top surface of the cover plate, the upper and lower ends of the stiffening rib are respectively connected to the upper pad and the lower pad, and the injection pipe is located between the upper pad and the lower pad.

[0013] Furthermore, the bottom plate is provided with a plurality of clearance grooves, which are connected to the injection hole, and the width of the clearance grooves is slightly larger than the width of the injection pipe. By providing the clearance grooves, the injection pipe is given a clearance, which facilitates the connection of the test device.

[0014] Furthermore, the stiffening ribs include inner stiffening ribs and side stiffening ribs, the inner stiffening ribs are cross-shaped, the outer sides of the inner stiffening ribs are respectively vertically connected to the side stiffening ribs, and the clearance grooves are located between two adjacent side stiffening ribs. By providing the inner stiffening ribs and the side stiffening ribs, the space between the upper pad and the lower pad is supported, the structural strength between the upper and lower pads is enhanced, and the upper and lower pads are prevented from being deformed when the axial loading device applies axial pressure to the upper and lower pads, thereby damaging the injection pipe.

[0015] Furthermore, it also includes upper stiffening ribs and lower stiffening ribs, wherein the upper stiffening ribs connect the outer wall of the steel pipe column and the bottom surface of the cover plate, and the lower stiffening ribs connect the outer wall of the steel pipe column and the top surface of the bottom plate. By providing the upper stiffening ribs and the lower stiffening ribs, the connection strength between the steel pipe column and the cover plate and the bottom plate is enhanced.

[0016] Another technical solution of the present invention is: the test method of the above-mentioned steel pipe column axial compression test device subjected to internal local lateral pressure comprises the following steps:

[0017] Step S1: The area separation support assembly supports the middle area of ​​the inner wall of the steel pipe column, and the space in the steel pipe column is divided into multiple edge areas. The area separation support assembly is used to support the steel pipe column during the test, simulating the rigid medium effect of concrete to prevent the steel pipe column from partially buckling inward. The bottom of the area separation support assembly and the steel pipe column are welded to the bottom plate respectively;

[0018] Step S2: placing the filling bag in the edge area, and then welding the cover plate to the top of the steel pipe column;

[0019] Step S3: installing the loading assembly to the top surface of the cover plate, the injection tube is connected to the filling bag through the loading assembly and the injection tube on the cover plate, and the external axial loading device applies axial pressure to the loading assembly;

[0020] Step S4: The local pressurizing component is used to inject filler into the filling bag through the injection tube, so that the filling bag expands and abuts the edge area inside the steel pipe column, providing lateral pressure for the steel pipe column. The pressure of the filling bag is controlled by adjusting the amount of filler, thereby adjusting the lateral pressure on the steel pipe column.

[0021] The working principle of the above-mentioned axial compression test device for steel pipe columns subjected to internal local lateral pressure is as follows: the filling bag is filled with water through a connecting pipe. The filling bag gradually expands as it is filled with water and abuts against the edge area inside the steel pipe column to provide lateral pressure for the steel pipe column. The digital pressure gauge is used to check the pressure inside the filling bag. The high-precision frequency conversion control box controls the frequency conversion water pump to change the water supply pressure, further adjusts the pressure inside the filling bag, and realizes the adjustment of the lateral pressure on the steel pipe column.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The axial compression test device for steel pipe columns subjected to internal local lateral pressure of the present invention adopts steel pipe columns as main load-bearing components and can be used to study the load-bearing performance of steel pipe columns of various materials under the combined action of axial force and lateral forces of different magnitudes in different areas.

[0024] The axial compression test device for steel pipe columns subjected to internal local lateral pressure of the present invention innovatively arranges a water bag in the inner edge area of ​​the steel pipe column, and applies lateral pressure to the inside of the steel pipe column by injecting water and pressurizing the water bag. The digital pressure gauge can realize real-time observation of the internal pressure of the water bag, and the variable frequency water pump is controlled by a high-precision variable frequency controller to further control the water pressure in the connecting pipe, thereby realizing the adjustment of the lateral pressure exerted on the steel pipe column.

[0025] The axial compression test device for steel pipe columns subjected to internal local lateral pressure of the present invention effectively distinguishes the areas inside the steel pipe columns where lateral pressure needs to be applied through regional separation support components, thereby achieving adjustable positions of the areas where the steel pipe columns are subjected to lateral pressure and providing rigid support for the steel pipe columns at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the assembly of the steel pipe column and the loading assembly of the present invention.

[0027] Figure 2 for Figure 1 Top view of the .

[0028] Figure 3 for Figure 1 Section view along line AA.

[0029] Figure 4 for Figure 1 Section view along line BB.

[0030] Figure 5 for Figure 2 Cross-sectional view along line CC.

[0031] Figure 6 It is a schematic diagram of the overall structure of the test device of the present invention.

[0032] Steel pipe column 1, base plate 2, cover plate 3, filling bag 4, upper stiffening rib 5, lower stiffening rib 6, supporting steel plate 7, transverse supporting rib 8, partition steel plate 9, upper pad 10, lower pad 11, inner stiffening rib 12, side stiffening rib 13, injection hole 14, injection pipe 15, make way groove 16, digital pressure gauge 17, flow valve 18. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0034] Example

[0035] like Figure 1 and Figure 6 As shown, this embodiment provides an axial compression test device for a steel pipe column subjected to internal local lateral pressure, including a local pressurization component, a steel pipe column 1, a regional separation support component, a loading component, a base plate 2, a cover plate 3, a filling bag 4, an upper stiffening rib 5 and a lower stiffening rib 6.

[0036] like Figure 4 and Figure 5As shown, the steel pipe column is square, and the regional separation support assembly includes multiple support steel plates 7, multiple transverse support ribs 8 and multiple separation steel plates 9. The support steel plates are close to the middle area of ​​each side of the steel pipe column, and the two ends of the transverse support ribs are respectively welded to the two opposite support steel plates. The two sides of the support steel plates are respectively connected to the separation steel plates, one side of the separation steel plate is connected to the side of the support steel plate, and the other side is connected to the middle of the transverse support ribs. An edge area is formed between the separation steel plates on two adjacent support steel plates. In this embodiment, the regional separation support assembly divides the space in the steel pipe column into four edge areas, and each edge area is provided with a filling bag. In this embodiment, the filling bag is a water bag made of rubber. The separation steel plates on both sides of the support steel plate are arranged together with the support steel plate to form a triangle. The triangular structure is used to enhance the structural strength of the regional separation support assembly, enhance the force-bearing capacity, and strengthen the support for the steel pipe column. The area separation support assembly is used to support the steel pipe column during the test, simulating the rigid medium effect of concrete to prevent the steel pipe column from local buckling inward. It also has the area separation function, which can separate the middle area and edge area of ​​each side of the steel pipe column, providing loading space and partition for applying different loads.

[0037] like Figure 1 and Figure 5 As shown, the bottoms of the steel pipe column and the multiple supporting steel plates are welded to the bottom plate, the top of the steel pipe column is welded to the cover plate, the upper stiffening rib connects the outer wall of the steel pipe column and the bottom surface of the cover plate, and the lower stiffening rib connects the outer wall of the steel pipe column and the top surface of the bottom plate. By setting the upper stiffening rib and the lower stiffening rib, the connection strength between the steel pipe column and the cover plate and the bottom plate is enhanced.

[0038] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, the external axial loading device is used to apply axial force to the loading assembly, and the loading assembly includes an upper pad 10, a lower pad 11 and a stiffening rib. The lower pad is welded to the top surface of the cover plate, and the upper and lower ends of the stiffening rib are respectively connected to the upper pad and the lower pad. The stiffening rib includes an inner stiffening rib 12 and a side stiffening rib 13. The inner stiffening rib is cross-shaped, and the outer sides of the inner stiffening rib are respectively vertically connected to the side stiffening ribs. The space between the upper pad and the lower pad is supported by arranging the inner stiffening rib and the side stiffening rib, so as to enhance the structural strength between the upper and lower pads and prevent deformation when the axial loading device applies axial pressure to the upper pad and the lower pad. The cover plate and the lower pad are respectively provided with injection holes 14, and the injection pipe 15 is connected to the filling bag through the injection hole. The injection pipe is welded to the cover plate, and the lower pad is provided with a plurality of clearance grooves 16, which are connected to the injection hole, and the clearance groove is located between two adjacent side stiffening ribs. The width of the clearance groove is slightly larger than the width of the injection pipe. By setting a clearance groove, the injection pipe is given a clearance so that the injection pipe is located between the upper pad and the lower pad.

[0039] like Figure 6 As shown, the local pressurization component includes a water tank, a variable frequency water pump, a high-precision variable frequency control box and a connecting pipe. The connecting pipe is a DN25 connecting pipe. The water tank is connected to the injection pipe through the connecting pipe. The variable frequency water pump is connected between the water tank and the connecting pipe. The connecting pipe is provided with a digital pressure gauge 17 and a flow valve 18. The digital pressure gauge is used to check the water pressure in the connecting pipe. The variable frequency water pump is electrically connected to the high-precision variable frequency control box. By filling the filling bag with water to perform local pressurization, the cost is low, the safety factor is high, and the operation is easy.

[0040] The test method of the above-mentioned steel pipe column axial compression test device subjected to internal local lateral pressure comprises the following steps:

[0041] Step S1: The area separation support assembly supports the middle area of ​​the inner wall of the steel pipe column, and the space in the steel pipe column is divided into multiple edge areas. The area separation support assembly is used to support the steel pipe column during the test, simulating the rigid medium effect of concrete to prevent the steel pipe column from partially buckling inward. The bottom of the area separation support assembly and the steel pipe column are welded to the bottom plate respectively;

[0042] Step S2: placing the filling bag in the edge area, and then welding the cover plate to the top of the steel pipe column;

[0043] Step S3: installing the loading assembly to the top surface of the cover plate, the injection tube is connected to the filling bag through the loading assembly and the injection tube on the cover plate, and the external axial loading device applies axial pressure to the loading assembly;

[0044] Step S4: The local pressurizing component is used to inject filler into the filling bag through the injection tube, so that the filling bag expands and abuts the edge area inside the steel pipe column, providing lateral pressure for the steel pipe column. The pressure of the filling bag is controlled by adjusting the amount of filler, thereby adjusting the lateral pressure on the steel pipe column.

[0045] The working principle of the above-mentioned axial compression test device for steel pipe columns subjected to internal local lateral pressure is as follows: the filling bag is filled with water through a connecting pipe. The filling bag gradually expands as it is filled with water and abuts against the edge area inside the steel pipe column to provide lateral pressure for the steel pipe column. The digital pressure gauge is used to check the pressure inside the filling bag. The high-precision frequency conversion control box controls the frequency conversion water pump to change the water supply pressure, further adjusts the pressure inside the filling bag, and realizes the adjustment of the lateral pressure on the steel pipe column.

[0046] As described above, the present invention can be better implemented. The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention; that is, all equivalent changes and modifications made according to the content of the present invention are covered by the scope of protection required by the claims of the present invention.

Claims

1. An axial compression test device for a steel pipe column subjected to internal local lateral pressure, characterized in that: It includes a local pressurization component, a steel pipe column, a regional separation support component, a loading component, a base plate, a cover plate, a filling bag and an injection pipe; The bottoms of the steel pipe column and the regional separation support assembly are both connected to the bottom plate. The regional separation support assembly is located inside the steel pipe column. The regional separation support assembly abuts against the middle area of ​​the inner wall of the steel pipe column and divides the space inside the steel pipe column into multiple edge areas. A filling bag is placed in each edge area. The top of the steel pipe column is connected to the cover plate. The top surface of the cover plate is connected to the loading assembly. The external axial loading device is used to apply an axial force to the loading assembly. The loading assembly and the cover plate are respectively provided with injection holes. The injection pipe is connected to the filling bag through the injection hole. The local pressurizing assembly is connected to the injection pipe. The local pressurizing assembly is used to inject filler into the filling bag through the injection pipe, so that the filling bag expands and abuts against the edge area inside the steel pipe column. The filling bag is used to provide lateral pressure for the steel pipe column. The area separation support assembly includes multiple support steel plates, multiple transverse support ribs and multiple separation steel plates. The support steel plates are close to the middle area of ​​the inner wall of the steel pipe column. The two ends of the transverse support ribs are respectively connected to two opposite support steel plates. The two sides of the support steel plates are respectively connected to the separation steel plates. One side of the separation steel plate is connected to the side of the support steel plate, and the other side is connected to the transverse support ribs. An edge area is formed between the separation steel plates on two adjacent support steel plates. The loading assembly includes an upper pad, a lower pad and a stiffening rib, the lower pad is connected to the top surface of the cover plate, the upper and lower ends of the stiffening rib are respectively connected to the upper pad and the lower pad, and the injection pipe is located between the upper pad and the lower pad.

2. The axial compression test device for steel pipe columns subjected to internal local lateral pressure according to claim 1 is characterized in that: The filling bag is a water bag, and the local pressurization component includes a water tank, a variable frequency water pump, a high-precision variable frequency control box and a connecting pipe. The water tank is connected to the injection pipe through the connecting pipe, and the variable frequency water pump is connected between the water tank and the connecting pipe. A digital pressure gauge and a flow valve are provided on the connecting pipe. The digital pressure gauge is used to check the water pressure in the connecting pipe. The variable frequency water pump is electrically connected to the high-precision variable frequency control box.

3. The axial compression test device for steel pipe columns subjected to internal local lateral pressure according to claim 1, characterized in that: The partition steel plates on both side edges of the supporting steel plate and the supporting steel plate are together arranged to form a triangle.

4. The axial compression test device for steel pipe columns subjected to internal local lateral pressure according to claim 1, characterized in that: The lower pad is provided with a plurality of clearance grooves, which are connected with the injection holes, and the width of the clearance grooves is slightly larger than the width of the injection pipe.

5. The axial compression test device for steel pipe columns subjected to internal local lateral pressure according to claim 1, characterized in that: The stiffening ribs include inner stiffening ribs and side stiffening ribs. The inner stiffening ribs are cross-shaped. The outer sides of the inner stiffening ribs are respectively vertically connected to the side stiffening ribs. The clearance grooves are located between two adjacent side stiffening ribs.

6. The axial compression test device for steel pipe columns subjected to internal local lateral pressure according to claim 1, characterized in that: It also includes upper stiffening ribs and lower stiffening ribs, wherein the upper stiffening ribs connect the outer wall of the steel pipe column and the bottom surface of the cover plate, and the lower stiffening ribs connect the outer wall of the steel pipe column and the top surface of the bottom plate.

7. A test method for the axial compression test device for a steel pipe column subjected to internal local lateral pressure according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1: The area separation support assembly supports the middle area of ​​the inner wall of the steel pipe column, and the space in the steel pipe column is divided into multiple edge areas. The area separation support assembly is used to support the steel pipe column during the test, simulating the rigid medium effect of concrete to prevent the steel pipe column from partially buckling inward. The bottom of the area separation support assembly and the steel pipe column are welded to the bottom plate respectively; Step S2: placing the filling bag in the edge area, and then welding the cover plate to the top of the steel pipe column; Step S3: installing the loading assembly to the top surface of the cover plate, the injection tube is connected to the filling bag through the loading assembly and the injection tube on the cover plate, and the external axial loading device applies axial pressure to the loading assembly; Step S4: The local pressurizing component is used to inject filler into the filling bag through the injection tube, so that the filling bag expands and abuts the edge area inside the steel pipe column, providing lateral pressure for the steel pipe column. The pressure of the filling bag is controlled by adjusting the amount of filler, thereby adjusting the lateral pressure on the steel pipe column.

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