A method for preparing a steel tube concrete specimen with internal void defects

Abstract

The present invention provides a method for making a steel tube concrete specimen with an internal hollow defect, and the method comprises the following steps: step 1, determining the parameters of the steel tube concrete specimen and preparing materials for making the steel tube concrete specimen; step 2, determining the hollow defect parameters and making a hollow defect model, wherein the hollow defect model can be melted at a set temperature; step 3, processing a steel tube and setting a reserved hole on the side wall of the steel tube; step 4, after the steel tube is erected, pouring concrete into the steel tube; step 5, placing the hollow defect model inside the steel tube; step 6, continuing to pour concrete into the steel tube and completing the whole steel tube concrete specimen making; step 7, heating the side wall of the steel tube at the hollow defect position to a set temperature to melt the hollow defect model; step 8, performing a loading test of the steel tube concrete specimen. The method can form a steel tube concrete specimen without an internal prefabricated model to ensure that the test is not affected by the prefabricated model.

Description

Technical Field

[0001] The invention belongs to the technical field of steel tube concrete production, and in particular relates to a method for producing a steel tube concrete specimen with an internal void defect. Background Art

[0002] Steel tube concrete structures have been widely used in building structures, especially high-rise building structures. During the construction process, due to the influence of construction technology, raw material quality and construction environment, debonding (debonding) often occurs between the steel tube and the concrete in the steel tube concrete structure. The debonding phenomenon will affect the mechanical properties and safety performance of steel tube concrete components. Therefore, in order to accurately evaluate the actual bearing capacity of steel tube concrete components with debonding, it is very important to make steel tube concrete specimens that can reflect the actual debonding situation.

[0003] Existing research on the production of steel tube concrete components with internal void defects shows that the production of void defects that penetrate to the top surface of the steel tube concrete is the most common. This method pulls out the template embedded in the inner side of the steel tube after the concrete in the steel tube reaches a certain curing time to achieve the production of the internal void defects of the steel tube concrete; however, in actual projects, void defects often occur in the middle of the steel tube concrete component, and the void defects do not penetrate to the end surface of the component. This method is difficult to truly reflect the actual void situation of the steel tube concrete component.

[0004] In the prior art, a Chinese patent with publication number CN113640086A discloses a method for manufacturing a steel tube concrete void detection test piece, the key points of the technical solution are to fix the manufactured defect body on the inner wall of the steel tube, install a formwork and a strut inside the steel tube, pour concrete between the formwork and the inner wall of the steel tube and then maintain it, then remove the strut, formwork and steel tube, remove the defect body to obtain a prefabricated part, stick the prefabricated part to a specified position on the inner wall of the steel tube, and finally seal the lower end of the steel tube and pour concrete to obtain the steel tube concrete void detection test piece.

[0005] However, the above technical solution still has the following problems when making steel tube concrete hollow specimens: the existence of prefabricated parts will inevitably affect the bearing capacity of steel tube concrete, and their adhesion to the inner wall of the steel tube further aggravates this effect; the bonding strength between the surface of the prefabricated parts and the newly poured concrete cannot be judged, and the existence of the prefabricated parts itself will have a great influence on the molding quality of steel tube concrete and the bearing capacity of steel tube concrete specimens.

[0006] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0007] The object of the present invention is to provide a method for producing a steel tube concrete specimen with an internal void defect, so as to at least solve the above-mentioned problems existing in the prior art.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a steel tube concrete specimen with an internal void defect, the method comprising the following steps:

[0010] Step 1, determining the parameters of the steel tube concrete specimen required for the test, and preparing the materials for making the steel tube concrete specimen according to the parameters of the steel tube concrete specimen;

[0011] Step 2, determining the void defect parameters required for the test, and making a void defect model according to the void defect parameters, wherein the void defect model can be melted at a set temperature;

[0012] Step 3, processing the steel pipe, and setting a reserved hole on the side wall of the steel pipe with the hollow defect, wherein the reserved hole penetrates the side wall of the steel pipe and corresponds to the hollow defect position designed inside the steel pipe, and the size of the reserved hole does not affect the mechanical properties of the steel pipe concrete specimen;

[0013] Step 4, after the steel pipe is erected, concrete is poured into the steel pipe until the concrete is poured below the reserved hole;

[0014] Step 5: placing the hollow defect model inside the steel pipe according to the designed internal hollow defect position, and the hollow defect model blocks the reserved hole;

[0015] Step 6, continue pouring concrete into the steel tube, complete the concrete pouring construction of the steel tube concrete specimen, and continue to complete the entire steel tube concrete specimen production;

[0016] Step 7, after the steel tube concrete specimen reaches the design strength, the side wall of the steel tube at the hollow defect position is heated to a set temperature so that the hollow defect model melts and flows out through the reserved holes;

[0017] Step 8: After the steel tube concrete specimen is left to stand until it is completely cooled, a loading test of the steel tube concrete specimen is performed.

[0018] In the method for preparing a steel tube concrete specimen with an internal void defect as described above, preferably, the void defect model is made of paraffin.

[0019] In the method for preparing a steel tube concrete specimen with an internal void defect as described above, preferably, the set heating temperature is higher than the melting point of paraffin.

[0020] In the method for preparing a steel tube concrete specimen with an internal void defect as described above, preferably, in step 3, a lower cover plate is provided at the bottom of the steel tube along the length direction, and the lower cover plate is used to close the bottom end of the steel tube.

[0021] In the method for making a steel tube concrete specimen with an internal void defect as described above, preferably, in step 6, the concrete is poured continuously to a position below the pipe mouth of the steel tube. After the concrete pouring is completed, when the concrete specimen reaches at least half of the set strength, the pipe mouth is filled with cement mortar of the same grade as the concrete, and then an upper cover plate is fixed on the top of the steel tube in the length direction.

[0022] In the method for preparing a steel tube concrete specimen with an internal void defect as described above, preferably, the time interval between pouring concrete again in step 6 and pouring concrete in step 4 is within five minutes.

[0023] In the method for manufacturing a steel tube concrete specimen with an internal void defect as described above, preferably, the reserved hole is set at the lowest point of the designed void defect position;

[0024] In step 5, when placing the hollow defect model, align the bottom of the hollow defect model with the bottom of the reserved hole.

[0025] In the method for producing a steel tube concrete specimen with an internal void defect as described above, preferably, a positioning block is provided on the inner wall of the steel tube, the positioning block corresponds to the middle of the designed void defect position, and the positioning block is provided above the reserved hole.

[0026] In the method for making a steel tube concrete specimen with an internal void defect as described above, preferably, a positioning groove is provided on the void defect model, and a positioning block is embedded in the positioning groove to fix the void defect model on the side wall of the steel tube.

[0027] The method for preparing a steel tube concrete specimen with an internal void defect as described above is preferably characterized in that the cross section of the steel tube is a square, and the void defect model is a cuboid;

[0028] The steel pipe is a welded steel pipe or a seamless steel pipe, and the central axis of the hollow defect model coincides with the central axis of the steel plate on the side where the defect is located.

[0029] Beneficial effects: The method for making a steel tube concrete specimen with internal void defects provided in the present application can make steel tube concrete specimens with internal void defects of different shapes and different geometric sizes, and provide technical support for the study of mechanical properties of steel tube concrete specimens with internal void defects. The void defect model is made of meltable materials, and can form a steel tube concrete specimen without an internal prefabricated model, ensuring that the steel tube concrete specimen is not affected by the prefabricated parts, and is made of paraffin, the material is easy to obtain, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0031] Figure 1 It is a schematic flow chart of a method for preparing a steel tube concrete specimen with internal void defects according to an embodiment of the present invention;

[0032] Figure 2 It is a structural schematic diagram of a steel pipe and reserved holes in an embodiment of the present invention;

[0033] Figure 3 for Figure 2 A cross-sectional view of

[0034] Figure 4 It is a schematic diagram of pouring concrete below a reserved hole in an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of placing a void defect model in an embodiment of the present invention;

[0036] Figure 6 Schematic diagram of pouring remaining concrete in a steel pipe according to an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of welding an upper cover plate on the top of a steel pipe in an embodiment of the present invention;

[0038] Figure 8 for Figure 7 Enlarged view of point A in the middle.

[0039] In the figure: 1. steel pipe; 2. lower cover plate; 3. steel plate on the side with hollow defect; 4. reserved holes; 5. concrete; 6. hollow defect model; 61. positioning groove; 7. upper cover plate; 31. positioning block. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0041] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0042] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0043] According to a specific embodiment of the present invention, Figure 1-8 As shown, the present invention provides a method for preparing a steel tube concrete specimen with an internal void defect, the preparation method comprising the following steps:

[0044] Step 1: determine the parameters of the steel tube concrete specimen required for the test, and prepare the materials for making the steel tube concrete specimen according to the parameters of the steel tube concrete specimen.

[0045] In this embodiment, the parameters of the steel tube concrete specimen are as follows: the cross section of the steel tube 1 is square, the cross-sectional size of the steel tube concrete specimen is 150mm*150mm, the side wall thickness of the steel tube 1 is 10mm, and the length of the steel tube concrete specimen is 1500mm; the material of the steel tube 1 is Q345B; the strength grade of concrete 5 is C55 self-compacting concrete, the cement is P.042.5 cement, and the mix ratio is: cement consumption 382kg, fine sand consumption 274kg, medium sand consumption 410kg, crushed stone consumption 985kg, water consumption 168kg, expansion agent consumption 46kg, fly ash consumption 64kg, and mineral powder consumption 87kg.

[0046] Step 2, determining the void defect parameters required for the test, and making a void defect model 6 according to the void defect parameters. The void defect model 6 can melt at a set temperature.

[0047] In this embodiment, the internal void defect is a rectangular defect with geometric dimensions of 30 cm long*10 cm wide*2 mm thick. The long side of the internal void defect is parallel to the length direction of the steel tube concrete specimen; the bottom side of the void defect is located 700 mm above the bottom of the steel tube concrete specimen. The central axis of the void defect model 6 coincides with the central axis of the steel plate 3 on the side of the void defect.

[0048] In this embodiment, the material used for the hollow defect model 6 is paraffin. In this embodiment, paraffin is selected as 50# semi-refined paraffin, which has a melting point of 51°C. The use of paraffin to make the hollow defect model 6 is not only convenient for model making and molding, but also has a low melting temperature of paraffin. The lower heating temperature has less effect on the steel tube concrete specimen, which can ensure that the accuracy of the steel tube concrete specimen itself is not affected, thereby ensuring the accuracy of the loading test of the steel tube concrete specimen.

[0049] Step 3, processing the steel pipe 1, the bottom of the steel pipe 1 along the length direction is provided with a lower cover plate 2, and the lower cover plate 2 is used to close the bottom of the steel pipe 1. A reserved hole 4 is provided on the steel plate 3 on the side of the hollow defect, and the reserved hole 4 penetrates the side wall of the steel plate 3 on the side of the hollow defect, and the reserved hole 4 corresponds to the hollow defect in the steel plate 3 on the side of the hollow defect. In this embodiment, the steel pipe is a welded steel pipe or a seamless steel pipe; specifically, the steel pipe 1 is welded from steel plates, and the steel pipe 1 is designed to be open at the top and welded and sealed with a lower cover plate 2 at the bottom. The lower cover plate 2 at the bottom is a cubic Q345B steel plate, and the specific dimensions are 220mm long*220mm wide*10mm thick.

[0050] The reserved hole is set corresponding to the bottom of the internal void defect, and the diameter of the reserved hole is 3 to 5 mm (any value between 3 and 5 can be selected), so as not to affect the mechanical properties of the steel tube concrete specimen. In this embodiment, the diameter of the reserved hole 4 is 3 mm, and the center of the reserved hole 4 is located on the longitudinal center axis of the steel plate 3 on the side of the void defect; the center of the reserved hole 4 is located 701.5 mm above the bottom of the steel tube concrete specimen.

[0051] Step 4, placing the steel pipe 1 upright, and then pouring concrete 5 into the steel pipe 1, and pouring the concrete 5 to the bottom of the reserved hole 4. Specifically, a vertical manual pouring method is adopted; the concrete 5 is first poured to the position 1.5mm below the bottom of the reserved hole 4.

[0052] Step 5, according to the designed internal hollow defect position, the hollow defect model 6 is placed inside the steel pipe, and the hollow defect model 6 can block the reserved hole 4; the reserved hole 4 is set at the lowest point of the designed hollow defect position; specifically, when placing the hollow defect model 6, the bottom of the hollow defect model 6 is aligned with the bottom of the reserved hole 4.

[0053] The bottom of the void defect model 6 is aligned with the bottom of the reserved hole 4, so that the reserved hole 4 is located at the lowest point of the void defect model 6. After the paraffin is melted, all the paraffin can flow out of the reserved hole 4, so that there is no paraffin in the designed void defect area, thereby ensuring that the loading test of the steel tube concrete specimen is not affected by the void defect model 6.

[0054] In this embodiment, a positioning block 31 is provided on the inner wall of the steel pipe, and the positioning block 31 corresponds to the middle of the designed hollow defect position, and the positioning block 31 is arranged above the reserved hole 4. A positioning groove 61 is provided on the hollow defect model 6, and the positioning block 31 is embedded in the positioning groove 61 to fix the hollow defect model 6 on the side wall of the steel pipe. The positioning block 31 is provided to facilitate the installation and fixation of the hollow defect model 6, and ensure that the hollow defect position in the manufactured steel tube concrete specimen is more accurate.

[0055] Step 6, continue pouring concrete 5 into the steel tube 1, complete the concrete pouring construction of the steel tube concrete specimen, and continue to complete the entire steel tube concrete specimen production.

[0056] When pouring the concrete 5, the concrete 5 is poured to a position lower than the mouth of the steel pipe 1. After the concrete 5 in the steel pipe 1 is poured, when the concrete 5 in the steel pipe 1 reaches at least half of the set strength, the mouth is filled with cement mortar of the same grade as the concrete, and then an upper cover plate 7 is welded and fixed to the top of the length direction of the steel pipe 1. The upper cover plate 7 and the lower cover plate 2 are provided to close the two ends of the steel pipe in the length direction, thereby completing the production of the steel pipe concrete test piece.

[0057] In this embodiment, the cement mortar is made of M55 cement paste. The time interval between the second concrete pouring and the concrete pouring in step 4 is within two minutes to ensure the pouring quality of the concrete; during the pouring, the position of the hollow defect wax model remains unchanged and the whole is intact.

[0058] Step 7, after the steel tube concrete specimen reaches the design strength, in this embodiment, the material of the hollow defect model 6 is paraffin wax, and the side wall of the steel tube at the hollow defect position is the hollow defect side steel plate 3; the hollow defect side steel plate 3 is heated, the paraffin wax reaches the melting point, the hollow defect model 6 made of paraffin wax melts, and all flows out through the reserved hole 4 to form a steel tube concrete specimen with an internal hollow defect. The set temperature of the heating is higher than the melting point of the paraffin wax, and the set temperature range is 55 to 60 degrees Celsius (any value between 55 and 60 can be selected).

[0059] Step 8: After the steel tube concrete specimen is left to stand until it is completely cooled, a loading test of the steel tube concrete specimen is performed. Specifically, the steel tube concrete specimen with internal void defects is left to stand for 24 hours until the steel tube concrete specimen is completely cooled, and then various mechanical property tests of the steel tube concrete specimen can be performed.

[0060] In summary, in the technical solution for preparing steel tube concrete specimens with internal void defects provided by the present invention, steel tube concrete specimens with internal void defects of different shapes and different geometric sizes can be prepared, providing technical support for the study of mechanical properties of steel tube concrete specimens with internal void defects. The void defect model is made of meltable materials, which can form steel tube concrete specimens without internal prefabricated models, ensuring that the steel tube concrete specimens are not affected by prefabricated parts, and paraffin is used for production, and the materials are easy to obtain and the cost is low.

[0061] It should be understood that the above description is merely exemplary and the embodiments of the present application do not limit this.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A method for preparing a steel tube concrete specimen with internal void defects, characterized in that: The production method comprises the following steps: Step 1, determining the parameters of the steel tube concrete specimen required for the test, and preparing the materials for making the steel tube concrete specimen according to the parameters of the steel tube concrete specimen; Step 2, determining the void defect parameters required for the test, and making a void defect model according to the void defect parameters, wherein the void defect model can be melted at a set temperature; Step 3, processing the steel pipe, and setting a reserved hole on the side wall of the steel pipe with the hollow defect, wherein the reserved hole penetrates the side wall of the steel pipe and corresponds to the hollow defect position designed inside the steel pipe; Step 4, after the steel pipe is erected, concrete is poured into the steel pipe until the concrete is poured below the reserved hole; Step 5: placing the hollow defect model inside the steel pipe according to the designed internal hollow defect position, and the hollow defect model blocks the reserved hole; Step 6, continue pouring concrete into the steel tube, complete the concrete pouring construction of the steel tube concrete specimen, and continue to complete the entire steel tube concrete specimen production; Step 7, after the steel tube concrete specimen reaches the design strength, the side wall of the steel tube at the hollow defect position is heated to a set temperature so that the hollow defect model melts and flows out through the reserved holes; Step 8, after the steel tube concrete specimen is left to stand until completely cooled, a loading test of the steel tube concrete specimen is performed, wherein the material used for the void defect model is paraffin; The reserved hole is arranged at the lowest point of the designed hollow defect position; In step 5, when placing the hollow defect model, align the bottom of the hollow defect model with the bottom of the reserved hole; A positioning block is arranged on the inner wall of the steel pipe, the positioning block corresponds to the middle of the designed hollow defect position, and the positioning block is arranged above the reserved hole; The hollow defect model is provided with a positioning groove, and the hollow defect model is fixed on the side wall of the steel pipe by a positioning block embedded in the positioning groove.

2. The method for preparing a steel tube concrete specimen with internal void defects according to claim 1, characterized in that: The heating is set to a temperature above the melting point of the paraffin.

3. The method for preparing a steel tube concrete specimen with internal void defects according to claim 1, characterized in that: In step 3, a lower cover plate is provided at the bottom of the steel pipe along the length direction, and the lower cover plate is used to close the bottom end of the steel pipe.

4. The method for preparing a steel tube concrete specimen with internal void defects according to claim 3, characterized in that: In step 6, continue pouring concrete to a position below the pipe mouth of the steel pipe. After the concrete pouring is completed, when the concrete specimen reaches at least half of the set strength, use cement mortar of the same grade as the concrete to fill the pipe mouth, and then fix an upper cover plate on the top of the steel pipe in the length direction.

5. The method for preparing a steel tube concrete specimen with internal void defects according to claim 4, characterized in that: The time interval between pouring concrete again in step 6 and pouring concrete in step 4 is within five minutes.

6. The method for preparing a steel tube concrete specimen with internal void defects according to any one of claims 1 to 5, characterized in that: The cross section of the steel pipe is a square, and the hollow defect model is a cuboid; The steel pipe is a welded steel pipe or a seamless steel pipe, and the central axis of the hollow defect model coincides with the central axis of the steel plate on the side where the defect is located.

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