Assembly type rectangular prefabricated column two-way threaded sleeve connecting structure and construction method thereof

Abstract

The invention discloses an assembly type rectangular prefabricated column two-way threaded sleeve connecting structure and a construction method thereof, and relates to the technical field of assembly type constructions.The assembly type rectangular prefabricated column two-way threaded sleeve connecting structure comprises an upper prefabricated column and a lower prefabricated column, inner threaded steel sleeves are embedded in the four corners of the section of the upper prefabricated column, and the axis of each sleeve 1 is connected with a column main rib through mechanical anchoring; a trapezoidal groove is formed in the center area of the sleeve group, the section size of the groove is 0.3 B * 0.3 H, the depth of the groove is h1, and exhaust holes are reserved in the bottom of the groove; a full-thread high-strength screw is preassembled in the corresponding position of the lower prefabricated column, and an annular fixing gasket and an elastic sealing washer are arranged at the two ends of the screw; the depth of the portion, pre-screwed into the sleeve, of the screw ranges from 20 cm to 30 cm, and the length of exposed threads ranges from 120 mm to 150 mm. Through coupling of the two-way threaded sleeve and the high-strength screw, the bearing efficiency of the joint under the axial pressure working condition reaches 95% or above of that of a cast-in-place joint, finite element analysis and actual tests show that the ultimate compressive strength of the joint can exceed 150 MPa, and the mechanical requirements of heavy-load structures such as high-rise buildings and large-span factory buildings are met.

Description

Technical Field

[0001] The present invention relates to the technical field of prefabricated buildings, and particularly to a two-way threaded sleeve connection structure for prefabricated rectangular columns and its construction method. Background Art

[0002] Due to advantages such as fast construction speed, low environmental pollution, and low labor demand, prefabricated buildings have been widely used in recent years in fields such as high-rise buildings, bridge projects, and industrial factories. However, the performance of connection nodes between prefabricated components has always been a key issue restricting the development of prefabricated structures. Traditional connection methods for prefabricated columns, such as welded connections, mechanical sleeve connections, or grouting sleeve connections, still have many technical bottlenecks in actual projects:

[0003] Specifically, although welded connections transmit force directly, on-site construction is greatly affected by weather conditions. High-temperature welding is likely to cause deterioration of steel performance, and it is difficult to ensure the quality of welds. Brittle fracture is likely to occur during long-term use, and the seismic performance is poor. Secondly, mechanical sleeve connections have extremely high requirements for construction accuracy, and the allowable error is usually not more than ±2 mm, which is difficult to meet in actual projects, and the node stiffness is insufficient, and it is easy to loosen under repeated loads. Grouting sleeve connections can partially improve the integrity, but the grouting density depends on manual operation, and it is easy to have cavities or bleeding, resulting in steel bar corrosion and a decrease in bearing capacity, and it is difficult to meet the requirements of high-intensity seismic areas.

[0004] The above information disclosed in this background art is only used to increase the understanding of the background art of the present invention. Therefore, it may include prior art that is not known to ordinary technicians in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a two-way threaded sleeve connection structure for prefabricated rectangular columns and its construction method to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] The two-way threaded sleeve connection structure for prefabricated rectangular columns includes:

[0008] Upper prefabricated column: Inner threaded steel sleeves are embedded at the four corners of its cross-section. The axis of the sleeve 1 is mechanically anchored to the column main reinforcement; a trapezoidal groove is provided in the central area of the sleeve group. The cross-sectional size of the groove is 0.3B×0.3H, the depth is h1, and exhaust holes are reserved at the bottom of the groove;

[0009] Lower prefabricated column: Fully threaded high-strength screws are pre-installed at corresponding positions. Annular fixed gaskets and elastic sealing gaskets are arranged at both ends of the screws; the depth of the screws pre-rotated into the sleeves is 20 - 30 cm, and the exposed threaded length is 120 - 150 mm;

[0010] Grouting layer: The trapezoidal groove is filled with UHPC ultra-high performance concrete, with a compressive strength greater than 150 MPa and a density greater than 98%.

[0011] Preferably, the mechanical anchoring method between the sleeve and the main reinforcement is thread connection or welding, and the inner wall of the sleeve is provided with thread teeth matching the main reinforcement.

[0012] Preferably, the elastic sealing washer is made of ethylene propylene diene monomer (EPDM) rubber or fluoroelastomer FKM, with a Shore hardness of 70±5, and forms a composite sealing system with the annular fixed gasket.

[0013] Preferably, the all-thread high-strength screw conforms to the ASTM A490 standard and its surface is treated with a dacromet coating or hot-dip galvanizing.

[0014] The construction method of the assembled rectangular precast column bidirectional thread sleeve connection structure includes the following steps:

[0015] Step 1: Calibrate the upper and lower precast columns through a three-dimensional laser positioning system, with the error controlled within ±5 mm;

[0016] Step 2: Use a reverse synchronous torque wrench to apply a 30° reverse rotation to the four-corner screws to achieve an axial displacement of 2 cm, and the synchronism error is within 5%;

[0017] Step 3: Pour self-compacting UHPC slurry into the trapezoidal groove 3, with a micro-vibration process frequency of 50 Hz, and form a grouting layer after curing for 72 hours;

[0018] Step 3: After the slurry pouring is completed, level the surface.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] Through the coupling of the bidirectional thread sleeve and the high-strength screw, the bearing efficiency of the joint under the axial compression condition reaches more than 95% of that of the cast-in-place joint. Finite element analysis and actual tests show that its ultimate compressive strength can exceed 150 MPa, meeting the mechanical requirements of heavy-load structures such as high-rise buildings and large-span factories.

[0021] Through the synergistic effect of the thread stress distribution design and the UHPC grouting layer, the seismic energy dissipation coefficient of the joint is greater than 0.35, far exceeding the national standard requirements. And in the seismic simulation test, the hysteresis curve of the joint is plump and there is no brittle failure, significantly improving the overall seismic reliability of the assembled structure.

[0022] Through the combination of three-dimensional laser positioning and reverse synchronous torque wrench, the alignment error of the present invention can be controlled within ±5 mm. Moreover, the trapezoidal groove and the pouring process of self-compacting UHPC eliminate the need for complex formwork support, greatly improving the engineering efficiency. The composite sealing system formed by the annular gasket and the elastic washer and the double protection of UHPC prevent the risk of slurry leakage and steel bar corrosion.

[0023] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic internal structure diagram of the upper precast column in the present invention;

[0025] Figure 2 It is a schematic internal structure diagram of the lower precast column in the present invention;

[0026] Figure 3 It is a schematic structure diagram of the four-corner screw, annular fixing gasket, and elastic sealing washer in the present invention.

[0027] In the figure: 1, sleeve; 2, main reinforcement; 3, trapezoidal groove; 4, exhaust hole; 5, four-corner screw; 6, annular fixing gasket; 7, elastic sealing washer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Embodiment 1

[0030] As shown in the attached Figure 1 - attached Figure 3 The structural parameters of the bidirectional threaded sleeve connection structure of the assembled rectangular precast column are as follows:

[0031] Precast column size: cross-section B×H = 600 mm×600 mm, column height 3.6 m.

[0032] Sleeve 1: internal threaded steel sleeve, specification M30×150 mm (thread major diameter 30 mm, length 150 mm), connected to the main reinforcement 2 by threads, and the thread profile matches HRB400 steel bars.

[0033] Screw 5: A fully threaded high-strength screw made of ASTM A490 material, with a diameter d = 24 mm, a Dacromet coating on the surface, a pre-inserted depth into the sleeve of 25 cm, and an exposed thread length X = 130 mm.

[0034] Sealing layer: The thickness t1 of the annular fixed gasket 6 is 5 mm, and the elastic sealing washer 7 is made of ethylene propylene diene monomer (EPDM) with a Shore hardness of 70.

[0035] Trapezoidal groove 3: The size is 0.3B×0.3H = 180 mm×180 mm, the depth h1 is 100 mm, and an exhaust hole 4 with a diameter of Φ10 mm is provided at the bottom.

[0036] Grouting material: Ultra-high performance concrete (UHPC), with a compressive strength of 158 MPa and a fluidity of 700 mm.

[0037] The construction method of the assembled rectangular precast column bidirectional threaded sleeve connection structure includes the following steps:

[0038] Use a three-dimensional laser positioning system to adjust the upper and lower precast columns, controlling the axis deviation within 3 mm.

[0039] Use a reverse synchronous torque wrench to synchronously rotate the four corner screws by 30°, achieving an axial displacement of 2 cm, with a synchronism error within 3%.

[0040] Pour self-compacting UHPC from one side of the trapezoidal groove, and at the same time use a 50 Hz micro-vibrator for vibration, with a density detection of 98.7%.

[0041] After pouring, cover with a film and cure for 72 hours, and level the surface to a flatness within 1 mm / m.

[0042] After curing, conduct an axial compression test. The test steps are as follows:

[0043] Use a 5000 kN hydraulic servo testing machine for loading, with a loading rate of 0.5 mm / min. There are 4 displacement sensors at the top of the column, 4 displacement sensors at the bottom of the column, 8 strain gauges placed in the sleeve area, and 4 strain gauges placed in the screw area. The experimental data is shown in the following table:

[0044]

[0045]

[0046] Experimental conclusion: The joint bearing efficiency is 96.2%, the UHPC grouting layer has slight cracking, and the screws have no slip.

[0047] Conduct a seismic test. The test steps are as follows:

[0048] The loading regime of the MTS bidirectional loading system uses the ISO 16633 standard, with a loading frequency of 0.5 Hz and a displacement amplitude of ±1 / 50 to ±1 / 20 of the column height. The hysteresis curve data is shown in the following table:

[0049] Number of cycles Displacement angle (rad) Maximum load (kN) Energy dissipation (kJ) 1 0.02 +1850 / -1820 12.5 3 0.04 +2100 / -2080 28.7 5 0.06 +2250 / -2230 45.2

[0050] Experimental conclusion: The equivalent damping ratio is 0.15, the stiffness degradation rate is 8% / cycle, and the energy dissipation coefficient η is 0.38.

[0051] Example 2

[0052] The structural parameters of the assembled rectangular precast column bidirectional threaded sleeve connection structure include:

[0053] Precast column size: cross-section B×H = 800 mm×800 mm.

[0054] Screw 5: diameter d = 30 mm, pre-insertion depth 28 cm, exposed length X = 150 mm.

[0055] Axial displacement: Rotating 35° achieves a displacement of 2.5 cm.

[0056] The construction method of the assembled rectangular precast column bidirectional threaded sleeve connection structure is different from that of Example 1 in that: a fluororubber sealing gasket is used, and the UHPC is doped with 2% volume fraction of steel fibers, and the compressive strength is increased to 165 MPa.

[0057] After curing is completed, fatigue testing is carried out. The testing steps are as follows:

[0058] The loading equipment uses a 1000 kN high-frequency fatigue testing machine, the stress ratio is 0.1, the loading frequency is 5 Hz, and the stress amplitude is ±150 MPa. The experimental results are shown in the following table:

[0059] Number of cycles (ten thousand times) Displacement amplitude (mm) Stiffness degradation (%) Temperature (°C) 10 0.12 2.1 35 20 0.15 4.3 42 50 0.21 8.7 55

[0060] Experimental conclusion: The screw breaks or the displacement amplitude exceeds 0.5 mm, and the actual number of failure cycles is 520,000 times.

[0061] Example 3, which is different from Examples 1 and 2 in that:

[0062] The screw is pre-inserted 20 cm, and the exposed length X = 100 mm. Rotating 25° under displacement control achieves a displacement of 1.5 cm, and the synchronization error is within 4%.

[0063] After curing is completed, the construction efficiency is tested. The testing process is as follows:

[0064] The calibration of the laser positioning system takes 8 minutes, the synchronous tightening of the four corners takes 22 minutes, the UHPC perfusion and vibration take 40 minutes in total, and the surface treatment takes 20 minutes. The experimental results are shown in the following table:

[0065]

[0066]

[0067] Experimental conclusion: The construction time of a single node is shortened by 57%, and the labor cost is reduced by 40%.

[0068] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not have to be directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0069] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. The assembled rectangular prefabricated column bidirectional threaded sleeve connection structure is characterized by: include: The upper prefabricated column: the four corners of the cross section are pre-buried with internally threaded steel sleeves (1), and the axis of the sleeve (1) is connected to the main reinforcement (2) of the column by mechanical anchoring; a trapezoidal groove (3) is arranged in the central area of ​​the sleeve group, the cross-sectional dimensions of the groove are 0.3B×0.3H, the depth is h1, and an exhaust hole (4) is reserved at the bottom of the groove; Lower prefabricated column: a fully threaded high-strength screw (5) is preinstalled at the corresponding position, and an annular fixing gasket (6) and an elastic sealing gasket (7) are arranged at both ends of the screw; the screw (5) is pre-screwed into the sleeve (1) to a depth of 20-30 cm, and the exposed thread length is 120-150 mm; Grouting layer: UHPC ultra-high performance concrete is poured into the trapezoidal groove (3), with a compressive strength greater than 150 MPa and a density greater than 98%.

2. The assembled rectangular prefabricated column bidirectional threaded sleeve connection structure according to claim 1 is characterized in that: The mechanical anchoring method of the sleeve (1) and the main reinforcement (2) is threaded connection or welding, and the inner wall of the sleeve is provided with a threaded tooth shape matching the main reinforcement (2).

3. The assembled rectangular prefabricated column bidirectional threaded sleeve connection structure according to claim 1 is characterized in that: The elastic sealing gasket (7) is made of EPDM rubber or fluororubber, has a Shore hardness of 70±5, and forms a composite sealing system with the annular fixing gasket (6).

4. The assembled rectangular prefabricated column bidirectional threaded sleeve connection structure according to claim 1 is characterized in that: The surface of the material of the full-thread high-strength screw (5) is treated with Dacromet coating or hot-dip galvanizing.

5. The construction method of the assembled rectangular prefabricated column bidirectional threaded sleeve connection structure is characterized in that: The following steps are involved: Step 1: Calibrate the upper and lower prefabricated columns through a three-dimensional laser positioning system, with the error controlled within ±5mm; Step 2: Use a reverse synchronous torque wrench to apply 30° reverse rotation to the square screw (5) to achieve an axial displacement of 2 cm with a synchronization error within 5%; Step 3: pouring self-compacting UHPC slurry into the trapezoidal groove (3), using a micro-vibration process, and curing for 72 hours to form a grouting layer; Step 3: After the slurry pouring is completed, the surface is smoothed.

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