A manufacturing method for tensile test specimens of fully grouted sleeves

Abstract

The invention discloses a method for fabricating a tensile test piece of a fully grouted sleeve. First, check the appearance, length, wall thickness, number of shear grooves of the closed ring, diameter, and mechanical properties of the sleeve body. Then, use the prepared special fixing frame. After inserting the first reinforcing bar into the lower end of the grouting sleeve body, put it in from the insertion port of the fixing frame and insert it into the groove. Fix the sleeve body with a fixing buckle to keep the sleeve body vertically fixed. Set the base surface of the limiting frame above the two steel bars. Insert the second reinforcing bar from the upper positioning pipe into the grouting sleeve. Insert the positioning pin from the base surface positioning hole to fix the limiting frame on the two steel bars of the upper positioning bar, ensuring that some reinforcing bars are vertically arranged in the center of the sleeve, some are offset, and some are inclined in the sleeve, perfectly simulating all possible structures in the actual construction process. Then, inject grouting material from the grouting hole, block the grouting hole and the slurry discharge hole after filling, and conduct tests after standard curing for 28 days to provide reference data for the next decision-making.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete structure engineering, and particularly relates to a method for manufacturing a tensile specimen of a fully grouted sleeve. Background Art

[0002] The construction of prefabricated buildings has become the development trend of building industrialization. The connection parts of prefabricated concrete structures are relatively small, and it is not convenient to construct using traditional steel bar connection methods such as binding and welding. The longitudinal steel bar connection in prefabricated structures usually adopts steel bar sleeve grouting connection. Currently, the commonly used connection methods include the full grouting connection method of inserting two steel bars to be connected into the grouting sleeve vertically and then pouring high-strength non-shrinking cement-based grouting material into the sleeve. The two steel bars need to be vertical, stable, and accurately positioned. To test the quality of the steel bar sleeve grouting connection, it is necessary to manufacture standard tensile specimens of the grouting sleeve for testing. In addition, during the actual construction process, the positions of the steel bars are not necessarily accurate and vertical, and the insertion depths may not meet the requirements. To simulate various steel bar insertion positions, depths, and angles on-site, manufacture tensile specimens, and test the actual tensile strength under various adverse factors on-site to prepare for future work. Therefore, it is necessary to develop a method for manufacturing a tensile specimen of a fully grouted sleeve. Summary of the Invention

[0003] To solve the above problems, the invention discloses a method for manufacturing a tensile specimen of a fully grouted sleeve, which is scientific, convenient, safe, simple to operate, with accurate steel bar positioning, convenient for grouting, and can ensure the stability of the specimen quality.

[0004] To achieve the above object, the technical solution of the invention is as follows:

[0005] A method for manufacturing a tensile specimen of a fully grouted sleeve includes the following steps:

[0006] (1) Manufacture a fixing frame;

[0007] (2) Prepare the required grouting sleeves, including purchasing the sleeve body, checking the appearance, length, wall thickness, number of closed-loop shear grooves, diameter, and mechanical properties of the sleeve body. The sleeve body is provided with the number of closed-loop shear grooves that meet the specification requirements, and the outside of the sleeve body is provided with grouting holes and slurry discharge holes;

[0008] (3) Insert the first steel bar into the lower grouting end of the grouting sleeve manufactured in step (2). After the insertion depth of the steel bar reaches the specification requirements, place it through the insertion pipe opening of the fixing frame. Insert the lower end of the grouting sleeve body into the groove, and insert the lower end of the first steel bar into the lower positioning pipe. The inner diameter of the rubber sleeve in the lower positioning pipe is 0.5 - 2 mm smaller than the diameter of the first steel bar. After the first steel bar and the grouting sleeve body are inserted, they are fixed in the lower positioning pipe;

[0009] (4) Fix the two steel bars of the lower positioning bar to the grouting sleeve body with fixed buckles, keep the grouting sleeve body vertically fixed, set the base surface of the limit frame above the two steel bars, insert the second steel bar from the upper positioning pipe into the grouting sleeve. The inner diameter of the rubber sleeve in the upper positioning pipe is 0.5 - 2 mm smaller than the diameter of the second steel bar. After the second steel bar is inserted, it is fixed in the upper positioning pipe. The included angle between the upper positioning pipe and the horizontal direction is 75 - 90°;

[0010] (5) Insert positioning pins from the base surface positioning holes to fix the limit frame on the two steel bars of the upper positioning bar;

[0011] (6) Inject grouting material from the grouting hole, block the grouting hole and the slurry discharge hole after filling, and the tensile test piece can be obtained after 28 days of standard curing.

[0012] Further, the fixing frame described in step (1) includes a cross bottom frame, an assembly frame, a positioning bar, and a limit frame. The cross bottom frame includes a left support plate, a right support plate, and a bottom plate. The bottom plate is fixed above the left support plate and the right support plate to form an inverted "U" shape. There is a groove on the front surface of the bottom plate, and several lower positioning pipes are provided on the back surface of the bottom plate. The assembly frame is divided into two and is arranged above both ends of the bottom plate. The positioning bar is divided into upper and lower groups, and each group of positioning bars includes two steel bars. The two steel bars are vertically connected to the assembly frame, and there is an insertion pipe opening between the two steel bars. The base surface of the limit frame is arranged above the two steel bars, there is an upper positioning pipe above the base surface, and several positioning holes are provided on the base surface. Rubber sleeves are provided at the bottom of the groove, inside the upper positioning pipe, and inside the lower positioning pipe.

[0013] Further, the included angle between the upper positioning pipe and the lower positioning pipe and the horizontal direction is 75 - 90°.

[0014] Further, the assembly frame is a square pipe or an angle iron.

[0015] Further, the number of the upper positioning pipes is the same as that of the lower positioning pipes, and their positions correspond to each other.

[0016] Further, the rubber sleeve at the bottom of the groove and the rubber sleeve inside the lower positioning pipe are integrally formed.

[0017] The beneficial effects of the present invention are:

[0018] For the method for manufacturing a fully grouted sleeve tensile test piece described in the present invention, by using a special fixing frame, in the obtained tensile test pieces, some steel bars are vertically arranged in the center of the sleeve, some steel bars are vertically arranged on one side of the sleeve, and some steel bars are inclined in the sleeve, perfectly simulating all possible structures in the actual construction process, providing reference data for the next decision-making; the entire manufacturing method is scientific, convenient, safe, simple to operate, with accurate steel bar positioning, convenient for grouting, capable of ensuring the stability of the test piece quality, and having a wide application range. Description of the Drawings

[0019] Figure 1 This is the front view of the fixing bracket described in the present invention.

[0020] Figure 2 This is a schematic diagram of the fixing bracket described in the present invention spanning the chassis.

[0021] Figure 3 This is the top view of the fixing bracket described in the present invention.

[0022] Figure 4 This is a schematic diagram of the bottom of the groove and the rubber sleeve inside the lower positioning tube described in the present invention.

[0023] Figure 5 This is a schematic diagram of the working state of making a tensile test piece described in the present invention.

[0024] List of reference numerals:

[0025] List of reference numerals:

[0026] 1. Left support plate, 2. Right support plate, 3. Bottom plate, 4. Groove, 5. Lower positioning tube, 6. Assembly frame, 7. Upper positioning strip, 8. Lower positioning strip, 9. Insertion tube opening, 10. Steel bar, 11. Limiting frame, 12. Base surface, 13. Upper positioning tube, 14. Positioning hole, 15. Rubber sleeve inside the upper positioning tube, 16. Sleeve body, 17. Closed ring shear groove, 18. Grouting hole, 19. Steel bar two, 20. Steel bar one, 21. Fixed buckle, 22. Rubber sleeve at the bottom of the groove and inside the lower positioning tube, 23. Drainage hole, 24. Positioning pin. Detailed implementation manners

[0027] The following further clarifies the present invention in conjunction with the accompanying drawings and specific implementation manners. It should be understood that the following specific implementation manners are only used to illustrate the present invention and not to limit the scope of the present invention. It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the accompanying drawings, and the terms "inner" and "outer" respectively refer to the directions towards or away from the geometric center of a specific component.

[0028] As shown in the figure, the fixing bracket of the present invention includes a cross bottom bracket, an assembly bracket 6, a positioning strip, and a limiting bracket 11. The cross bottom bracket includes a left support plate 1, a right support plate 2, and a bottom plate 3. The bottom plate 3 is fixed above the left support plate 1 and the right support plate 2 to form an inverted "U" shape. A groove 4 is provided on the front surface of the bottom plate 3, and several lower positioning tubes 5 are provided on the back surface of the bottom plate. The assembly brackets are two and are respectively arranged above both ends of the bottom plate. The positioning strips are two groups 7 and 8, each group of positioning strips includes two steel bars 10. The two steel bars are vertically connected to the assembly bracket 6, and an insertion tube opening 9 is provided between the two steel bars. The base surface 12 of the limiting bracket is arranged above the two steel bars 10. An upper positioning tube 13 is provided above the base surface, and several positioning holes 14 are provided on the base surface. Rubber sleeves 15 and 22 are provided at the bottom of the groove, inside the upper positioning tube, and inside the lower positioning tube.

[0029] Before use, first check the appearance, length, wall thickness, number of closed ring shear grooves, diameter, and mechanical properties of the sleeve body 16. The sleeve body 16 is provided with a number of closed ring shear grooves 17 that meet the specification requirements to increase the grasping force between the specimen and the side surface of the sleeve body 16. Grouting holes 18 and slurry discharge holes 23 are provided on the outer side of the sleeve body. Insert the first steel bar 20 into the grouting sleeve 16 at the grouting end below made in step (2). After the insertion depth of the steel bar reaches the specification requirements, put it in from the insertion tube opening 9 of the fixing bracket. The lower end of the grouting sleeve body is inserted into the groove 4 (the grouting sleeve body 16 is fixed to the lower positioning strip 8 with a fixing buckle 21 in the middle). The lower end of the first steel bar 20 is inserted into the lower positioning tube. The inner diameter of the rubber sleeve in the lower positioning tube 5 is 0.5 - 2 mm smaller than the diameter of the first steel bar. The first steel bar 20 together with the grouting sleeve body 16 is fixed in the lower positioning tube 5 after insertion. The height of the grouting sleeve body 16 is lower than the height of the upper positioning strip 7. As Figure 5 shown, 7 sleeve bodies 16 are vertically placed on the bottom plate 3. The lower positioning tubes 5 are straight and inclined, and the included angle between their axes and the horizontal direction is 75 - 90°. When the included angle is 90°, it is the vertical direction, and the lower positioning tubes 5 at other angles are in the inclined direction. Similarly, insert the second steel bar 19 into the upper positioning tube 13. The included angle between the upper positioning tube 13 and the horizontal direction is 75 - 90°, and it is also straight and inclined. When making, inject grouting material from the grouting hole 18, block the grouting hole 18 and the slurry discharge hole 23 after filling, and then insert the positioning pin 24 to fix the limiting bracket 11 on the two steel bars of the upper positioning strip 7 before the grouting material solidifies, ensuring that some steel bars (including the first steel bar and the second steel bar) are vertically arranged in the center of the sleeve, some steel bars are vertically arranged on one side (offset) of the sleeve, and some steel bars are inclined in the sleeve, perfectly simulating all possible structures in the actual construction process. After standard curing for 28 days, conduct a tensile test (the machine respectively grabs the first steel bar 20 and the second steel bar 19 and pulls outward, and records the tensile data) to provide reference data for the next decision-making.

[0030] As Figure 2As shown, the left support plate 1 and the right support plate 2 of the present invention are trapezoidal, with a wider bottom and a narrower top, so that the stability is better and it is convenient for the tensile test piece to be formed.

[0031] The groove 4 of the present invention is arranged on the bottom plate 3, which plays a role of spacing and rough positioning when the sleeve body 16 is put down. The size of the groove 4 is larger than the diameter of the sleeve body 16, which is convenient for the sleeve body 16 to move in the groove, so that the steel bar is in the center or offset position of the sleeve.

[0032] Rubber is arranged in the groove 4, which is convenient for taking out after pouring. In addition, the bottom of the groove 4 of the present invention is integrally formed with the rubber sleeve 22 in the lower positioning pipe 5, reducing the assembly steps and components and improving the work efficiency.

[0033] The assembly frame 6 of the present invention is a square pipe or an angle iron, ensuring that there is a notch as the insertion pipe opening 9 between the two steel bars, which is convenient for the sleeve body 16 to be put in.

[0034] The present invention can be combined according to the actual situation. The upper positioning pipe 13 and the lower positioning pipe 5 have the same number, but the angles and positions are not necessarily the same. For example, Figure 5 As shown,

[0035] For the sleeve body a, it is arranged in the center of the upper steel bar two 19 and in the center of the lower steel bar one 20;

[0036] For the sleeve body b, the upper steel bar two 19 is arranged offset, and the lower steel bar one 20 is arranged offset;

[0037] For the sleeve body c, the upper steel bar two 19 is arranged in the center, and the lower steel bar one 20 is arranged offset;

[0038] For the sleeve body d, the upper steel bar two 19 is arranged obliquely, and the lower steel bar one 20 is arranged in the center;

[0039] For the sleeve body e, the upper steel bar two 19 is arranged obliquely, and the lower steel bar one 20 is arranged obliquely;

[0040] For the sleeve body f, the upper steel bar two 19 is arranged offset, and the lower steel bar one 20 is arranged in the center;

[0041] For the sleeve body g, the upper steel bar two 19 is arranged obliquely, and the lower steel bar one 20 is arranged offset.

[0042] Through this device, various test pieces can be made, perfectly simulating all possible structures in the actual construction process (there can be other combinations, and there are also many kinds of inclination angles), which is convenient for analyzing the bearing limit of concrete in the most extreme cases and providing reference data for making decisions in special situations.

[0043] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A method for fabricating a tensile test piece of a fully grouted sleeve, characterized in that: The steps include: (1) Fabricate a fixing rack; The fixing rack includes a cross base frame, an assembly frame, positioning bars, and a limiting frame. The cross base frame includes a left support plate, a right support plate, and a bottom plate. The bottom plate is fixed above the left support plate and the right support plate to form an inverted "U" shape. There is a groove on the front surface of the bottom plate, and several lower positioning tubes are provided on the back surface of the bottom plate. The assembly frames are two and are respectively arranged above both ends of the bottom plate. The assembly frame is a square tube or an angle iron. The positioning bars are in two groups, upper and lower. Each group of positioning bars includes two steel bars. The two steel bars are vertically connected to the assembly frame, and there is an insertion tube opening between the two steel bars. The base surface of the limiting frame is arranged above the two steel bars. There are upper positioning tubes above the base surface. The number of upper positioning tubes is the same as that of the lower positioning tubes and their positions correspond. The included angle between the upper positioning tube and the lower positioning tube and the horizontal direction is 75 - 90°. There are several positioning holes on the base surface. Rubber sleeves are provided at the bottom of the groove, inside the upper positioning tube, and inside the lower positioning tube. The rubber sleeve at the bottom of the groove and the rubber sleeve inside the lower positioning tube are integrally formed; (2) Prepare the required grouting sleeve, including purchasing the sleeve body, checking the appearance, length, wall thickness, number of closed ring shear grooves, diameter, and mechanical properties of the sleeve body. The sleeve body is provided with the number of closed ring shear grooves that meet the specification requirements. There are grouting holes and slurry discharge holes on the outer side of the sleeve body; (3) Insert steel bar 1 into the lower grouting end of the grouting sleeve fabricated in step (2). After the insertion depth of the steel bar reaches the specification requirements, put it in from the insertion tube opening of the fixing rack. The lower end of the grouting sleeve body is inserted into the groove, and the lower end of steel bar 1 is inserted into the lower positioning tube. The inner diameter of the rubber sleeve in the lower positioning tube is 0.5 - 2 mm smaller than the diameter of steel bar 1. After steel bar 1 and the grouting sleeve body are inserted, they are fixed in the lower positioning tube; (4) Use a fixed buckle to fix the two steel bars of the lower positioning bar to the grouting sleeve body to keep the grouting sleeve body vertically fixed. Set the base surface of the limiting frame above the two steel bars of the upper positioning bar. Insert steel bar 2 into the grouting sleeve from the upper positioning tube. The inner diameter of the rubber sleeve in the upper positioning tube is 0.5 - 2 mm smaller than the diameter of steel bar 2. After steel bar 2 is inserted, it is fixed in the upper positioning tube. The included angle between the upper positioning tube and the horizontal direction is 75 - 90°; (5) Insert a positioning pin into the positioning hole on the base surface to fix the limiting frame to the two steel bars of the upper positioning bar; (6) Inject grouting material from the grouting hole. After filling, block the grouting hole and the slurry discharge hole. After standard curing for 28 days, a tensile test piece can be obtained.

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