Steel pipe and concrete interface bond slip performance test device

Abstract

The utility model discloses a steel pipe and concrete interface bond-slip performance testing device, which solves the problem of lack of testing equipment for researching the bonding strength (single element) between a steel pipe and concrete. The testing device comprises a supporting frame, a supporting cylinder, a limiting ring and a concrete-filled steel tube test piece, the supporting cylinder is mechanically installed on the supporting frame and is in a suspended state, the concrete-filled steel tube test piece is located in the supporting cylinder, and the limiting ring is arranged between the supporting cylinder and the concrete-filled steel tube test piece. The at least two limiting rings are used for annularly restraining the upper end and the lower end of the concrete-filled steel tube test piece, and the pressure sensor is used for detecting the pressure stress in the concrete; the tensile stress strain gauge detects stress generated by expansion of the steel pipe. According to the utility model, the concrete filled steel tube sample inside is effectively placed, and a reasonable gap is kept between the sample and the supporting cylinder. Due to the existence of the gap, the sample has an external expansion space, so that experimental data are closer to reality.

Description

Technical Field

[0001] The utility model relates to the technical field of concrete performance testing. Background Art

[0002] Steel tube concrete refers to a load-bearing component formed by filling concrete in a steel tube. The steel tube and the concrete inside the steel tube jointly bear the external load. Therefore, compared with reinforced concrete columns, the steel tube constrains the concrete inside the steel tube, which puts the concrete in a three-dimensional compressive state, thereby improving the compressive strength of the concrete. At the same time, the concrete inside the steel tube can effectively prevent local buckling of the steel tube, further transforming the damage of the concrete inside the steel tube from brittle damage to plastic damage, and significantly improving the performance.

[0003] The bond strength between steel pipes and concrete (single element) was studied in the laboratory.

[0004] The research results on the interfacial bonding performance between steel pipes and concrete have positive significance in civil engineering. For example, through this research, we can obtain and discover the optimal cross-sectional form, optimal aggregate ratio, aspect ratio, and the effects of various additives on concrete strength.

[0005] The implementation of this technology is based on the beneficial common sense gained in this context. Utility Model Content

[0006] In order to address the deficiencies of the prior art, the utility model provides a steel pipe and concrete interface bond slip performance test device to solve the problem of lack of test equipment for studying the bonding strength (single element) between steel pipes and concrete.

[0007] The technical solution adopted by the utility model to solve its technical problems is:

[0008] A device for testing the bond slip performance of the interface between a steel tube and concrete comprises a support frame, a support tube, a limiting ring and a steel tube concrete specimen, wherein the support tube is mechanically mounted on the support frame and is in a suspended state, the steel tube concrete specimen is located inside the support tube and a limiting ring is arranged between the two, there are at least two limiting rings and they perform circumferential constraints on the upper and lower ends of the steel tube concrete specimen, a pressure sensor is arranged in the concrete of the steel tube concrete specimen, and the pressure sensor detects the compressive stress inside the concrete; a tensile stress strain gauge is adhered to the outer wall of the steel tube of the steel tube concrete specimen, and the tensile stress strain gauge detects the stress generated by the expansion of the steel tube.

[0009] Furthermore, the support frame is composed of a base plate and a vertical tube, wherein the vertical tube is perpendicular to the base plate and fixed by welding.

[0010] Furthermore, the bottom plate has a circular outline structure, a window is provided at the center of the bottom plate and a plug is installed.

[0011] Furthermore, the support cylinder is a steel cylinder, and the outer wall of the support cylinder is designed to have a constant diameter.

[0012] Furthermore, a support ring is provided near the top of the support tube, and the support ring is in abutment with the top of the vertical tube in the support frame.

[0013] Furthermore, the limiting ring is a hard rubber piece or a copper piece.

[0014] Furthermore, a gap is maintained between the support tube and the sample.

[0015] Furthermore, the support frame is composed of a base plate and columns, wherein the columns are perpendicular to the base plate and are fixed by welding.

[0016] The beneficial effects of the utility model are:

[0017] The utility model effectively places the steel tube concrete sample inside and maintains a reasonable gap between the sample and the support tube. The existence of this gap can provide space for the sample to expand outward, making the experimental data closer to reality.

[0018] The utility model has a simple structure and can be quickly assembled and disassembled, meeting the use requirements of the laboratory. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the utility model.

[0020] Figure 2 A cross-sectional view of the support tube.

[0021] In the picture:

[0022] 00 press loading head,

[0023] 10 support frame, 11 bottom plate, 12 vertical cylinder, 13 plug,

[0024] 20 support cylinder, 21 mounting annular groove, 22 shaft shoulder, 23 support ring,

[0025] 30 limit ring,

[0026] 40 steel tube concrete specimens,

[0027] 51 pressure sensor, 52 tensile stress strain gauge. DETAILED DESCRIPTION

[0028] Example 1

[0029] This example is based on a circular steel tube and a concrete specimen filled inside.

[0030] refer to Figure 1 , a device for testing the bond slip performance of the interface between steel pipe and concrete, which is carried out in conjunction with a pressure testing machine, includes a support frame 10, a support tube 20, a limiting ring 30 and a steel tube concrete specimen 40, wherein the support frame supports the support tube so that the support tube is in a suspended state, the steel tube concrete specimen is located inside the support tube and a limiting ring is set between the two, and there are at least two limiting rings, which respectively constrain the upper and lower ends of the steel tube concrete specimen.

[0031] The support frame 10 is composed of a base plate 11 and a vertical tube 12, wherein the vertical tube 12 is perpendicular to the base plate 11 and fixed by welding. The height of the vertical tube is relatively high, forming sufficient supporting space for the support tube.

[0032] Furthermore, the base plate 11 has a circular profile and bears some of the impact from concrete falling from the steel pipe. Therefore, a window is preferably provided in the center of the base plate 11. This window is threaded, allowing a plug 13 to be installed through the threaded connection. This plug forms a removable connection to the base plate 11. This plug 13 can be made of engineering plastic and can be replaced after concrete impacts, which has a positive impact on the service life of the device.

[0033] Support cylinder 20, reference Figure 2 The support tube is a steel tube structure. The outer wall of the support tube 20 is designed with a constant diameter. A mounting annular groove 21 is formed by lathing at the top of the support tube 20. A retaining ring 30, labeled the upper retaining ring, is placed within this mounting annular groove. There is also a shoulder 22 at the bottom of the support tube, where a retaining ring 30, labeled the lower retaining ring, is placed. The steel tube concrete specimen 40 is installed from top to bottom within the support tube, with the shoulder 22 below forming a vertical constraint. The shoulder is sized to support only the steel tube within the steel tube concrete, avoiding the concrete.

[0034] A support ring 23 is located near the top of the support tube 20. Specifically, the highest point of the support tube is no more than 2 cm. The support ring 23 forms an extension on the outside of the support tube, which is used to mate with the top of the vertical tube in the support frame to form an overlap. During use, the middle and lower sections of the support tube 20 can be quickly inserted into the vertical tube for quick installation. Conversely, this structure also allows the support tube 20 to be quickly removed from the support frame, improving experimental efficiency.

[0035] Furthermore, the above-mentioned limiting ring 30 is an annular structure made of hard rubber or copper. The hardness of the limiting ring 30 is lower than the hardness of the steel pipe to be tested, and the steel tube concrete specimen is limited at the upper and lower ends to avoid shaking of the steel tube concrete specimen, so as to ensure the accuracy of the test results.

[0036] Furthermore, the above-mentioned support tube and support frame are both made of steel, and their wall thickness is several times that of the steel pipe, and they have sufficient tensile and compressive mechanical properties.

[0037] Under the action of the above-mentioned limiting ring 30, a gap of about 0.5 mm is maintained between the support tube and the sample. The existence of this gap allows the sample to have space for external expansion, avoiding obstruction and interference in the deformation of the steel tube in the steel tube concrete specimen, making the experimental data closer to reality.

[0038] The above-mentioned steel tube concrete specimen 40 is a component of a specific size, for example, a steel-concrete structure with a diameter of 0.1 meter and a height of 0.1 meter. According to the area formula, S=DH=0.01㎡.

[0039] The steps performed using this device are:

[0040] Step 1: Prepare test materials. Prepare concrete-filled steel tube specimens according to relevant standards. Each set of specimens must contain at least three specimens to facilitate control experiments. During specimen preparation, the concrete height must be strictly controlled, and a mold must be used to assist. During preparation, a pressure sensor 51 is embedded within the concrete, and a tensile stress strain gauge 52 is attached to the outer wall of the steel tube. The pressure sensor measures the compressive stress within the concrete, while the tensile stress strain gauge measures the stress generated by the expansion of the steel tube.

[0041] Step 2: Install the support frame 10, install the support frame on the press workbench, and strictly set the support frame concentrically with the press loading head 00, and the error should be less than 0.1mm.

[0042] Step 3: Place two limiting rings 30 on the outside of the steel tube concrete body sample and place it into the above-mentioned support tube from top to bottom, and then implant the support tube into the support frame from top to bottom.

[0043] Step 4: Calibrate the test equipment. Calibrate and zero the press and strain gauge. This involves applying the press loading head to the steel tube of the specimen, pressing it against the concrete core. The press automatically records the loading force and the vertical displacement of the loading head, while the strain gauge automatically records the data from the pressure sensor 51 and the tensile stress strain gauge 52.

[0044] Step 5: Start the test. According to the actual engineering simulation, apply vertical pressure. After applying vertical pressure, load step by step and obtain the readings of each sensor and strain gauge in real time until the steel pipe is completely separated from the concrete.

[0045] During the above experiment, the concrete itself is compressed, so the process should be slow. When damage occurs, the loading can be stopped.

[0046] Example 2

[0047] This example is based on a square steel tube and a concrete specimen filled inside.

[0048] Compared to Example 1, this embodiment features a modified support frame structure. Specifically, the support frame is composed of a base plate and columns. The columns are welded perpendicular to the base plate and are relatively tall, creating ample support space for the support tube. Each column corresponds to a side surface of the square steel tube, with four columns in total, forming an enclosed virtual support space.

[0049] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements to the present invention by relevant technical personnel in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A test device for the bond slip performance of a steel tube and concrete interface, comprising a support frame (10), a support cylinder (20), a limiting ring (30) and a steel tube concrete specimen (40), wherein: The support cylinder is mechanically mounted on the support frame and is in a suspended state. The steel tube concrete specimen is located inside the support cylinder and a limiting ring is provided between the two. There are at least two limiting rings that circumferentially constrain the upper and lower ends of the steel tube concrete specimen. A pressure sensor (51) is provided in the concrete of the steel tube concrete specimen (40), and the pressure sensor detects the compressive stress inside the concrete; A tensile stress strain gauge (52) is attached to the outer wall of the steel tube of the concrete-filled steel tube test piece (40), and the tensile stress strain gauge detects stress generated by expansion of the steel tube.

2. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 1, characterized in that: The support frame is composed of a base plate (11) and a vertical cylinder (12), wherein the vertical cylinder (12) is perpendicular to the base plate (11) and is fixed by welding.

3. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 2, characterized in that: The bottom plate (11) has a circular outline structure, and a window is provided at the center of the bottom plate (11) and a plug (13) is installed.

4. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 1, characterized in that: The support cylinder (20) is a steel cylinder, and the outer wall of the support cylinder (20) is designed to have a constant diameter.

5. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 4, characterized in that: A support ring (23) is provided near the top of the support tube (20), and the support ring (23) is in abutment with the top of the vertical tube in the support frame.

6. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 1, characterized in that: The limiting ring (30) is a hard rubber piece or a copper piece.

7. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 6, characterized in that: A gap is maintained between the support cylinder and the sample.

8. The device for testing the bond slip performance of the steel pipe and concrete interface according to claim 1, characterized in that: The support frame consists of a base plate and columns, wherein the columns are perpendicular to the base plate and are fixed by welding.

Images