Prestressed steel tie rods and their construction methods for cantilevered building platforms

Abstract

This invention relates to the field of building technology and discloses a prestressed steel tie rod for a cantilevered building platform and its construction method. The method includes: steel tie rod segments, multiple segments arranged in a straight line; a sleeve with internal threads at both ends, the ends of adjacent steel tie rod segments respectively installed within the internal threads; a first fastening nut structure installed at the end of each steel tie rod segment along the straight edge; and a second fastening nut structure installed at the end of at least one steel tie rod segment in the middle of the straight line, the second fastening nut structure being fitted into the sleeve. The prestressed steel tie rod for a cantilevered building platform and its construction method of this invention can offset the residual tensile force of the cantilevered platform load on the concrete structure, minimizing the risk of concrete cracking due to tension and ensuring structural construction safety.

Description

Technical Field

[0001] This invention relates to the field of building technology, specifically to a prestressed steel tie rod for a cantilevered building platform and its construction method. Background Technology

[0002] The existing technology describes a building with a total height of 206.75m, consisting of north and south towers. The south tower has 38 floors above ground and employs a frame-tube hybrid structure. The structural system is a steel-concrete composite column and beam frame-reinforced concrete core tube structure. The outer frame columns are cross-shaped steel-reinforced concrete columns, and the core tube contains H-shaped steel columns. The outer frame columns and the core tube are connected by H-beams and steel trusses, with buckling-restrained large diagonal braces. The south tower has cantilever structures at floors 14, 23, 32, and 38, all facing north. The cantilever structures utilize steel frame beams and steel trusses, with cantilever lengths of 23, 13, 13, and 28m respectively.

[0003] To improve structural stress and prevent the core tube concrete from cracking under tension during construction, prestressed steel tie rods need to be installed inside the core tube and on the roof truss, and a construction method for the prestressed steel tie rods is also required. Summary of the Invention

[0004] The purpose of this invention is to provide a prestressed steel tie rod for a cantilevered building platform; another purpose of this invention is to provide a construction method for the prestressed steel tie rod for a cantilevered building platform, so as to offset the residual tensile force of the cantilevered platform load on the concrete structure, thereby minimizing the cracking of the concrete due to tension and ensuring the safety of structural construction.

[0005] To achieve the above objectives, the present invention provides a prestressed steel tie rod for a cantilevered building platform, comprising:

[0006] The steel tie rod is segmented, and multiple steel tie rod segments are arranged in a straight line sequentially.

[0007] A sleeve, with internal threads at both ends of the sleeve, and the two ends of two adjacent steel tie rod segments are respectively installed in the internal threads;

[0008] A first fastening nut structure is installed at the end of the steel tie rod segment along the straight edge, and a second fastening nut structure is installed at the end of at least one steel tie rod segment in the middle of the straight line. The second fastening nut structure is fitted into the sleeve.

[0009] As a preferred embodiment, the ends of the steel tie rod segments are provided with external threads, which are matched and installed with the internal threads of the sleeve;

[0010] Both the first fastening nut structure and the second fastening nut structure include a thick nut and a thin nut that are sequentially threaded onto the external thread.

[0011] As a preferred embodiment, the steel tie rod is also provided with threads for connecting to the core tube shear wall.

[0012] A construction method for prestressed steel tie rods on a cantilevered platform of a building includes:

[0013] S1, Install H-beam steel columns;

[0014] S2, steel plates are welded to the edges of the H-shaped steel column to seal the internal space of the H-shaped steel column, forming grouting channels, and grouting is performed on the grouting channels;

[0015] S3, construction core tube shear wall;

[0016] S4, the first steel tie rod segment is connected to the lower part of the core tube shear wall through anchorage;

[0017] S5. Repeat steps S2 to S3 to connect the second steel tie rod segment to the first steel tie rod segment using a sleeve. Repeat step S4.

[0018] S6, Perform tensioning work on the installed steel tie rods in sections;

[0019] S61, steel tie rod anchorage installed and initially pre-tightened, exposing the threads;

[0020] S62, connect the extension rod to the threaded connection so that the extension rod extends to the top of the upper truss, and install the load-bearing frame, jack and tensioning anchor in sequence on the extension rod at the top of the upper truss;

[0021] S63. Use tensioning anchors to tension the steel tie rods. Each tensioning time shall be greater than or equal to 1 minute. After each tensioning is completed, use tensioning anchors to fix the tension rods.

[0022] As a preferred embodiment, step S3 further includes: tying the concrete reinforcement of the core tube shear wall and pouring the core tube concrete;

[0023] Step S4 further includes: connecting the first steel tie rod segment to the stiffening plate of the core tube shear wall through anchor bolts.

[0024] As a preferred embodiment, step S4 further includes: hoisting the steel tie rod to the core tube shear wall, wherein the hoisting construction includes at least two hoisting connectors, and the two hoisting connectors are respectively connected to the threads of the steel tie rod and the threads of the sleeve.

[0025] As a preferred embodiment, step S6 further includes: tensioning the steel tie rod after the concrete to be grouted reaches 95% strength.

[0026] As a preferred embodiment, step S62 further includes: the extension rod, the support frame, the jack, and the tensioning anchor should be arranged concentrically.

[0027] As a preferred embodiment, step S63 further includes:

[0028] During tensioning, the oil supply rate should be controlled, and the oil supply time should not be less than 0.5 minutes;

[0029] After the prestressed steel tie rods are tensioned, measurements and calibrations are performed.

[0030] As a preferred embodiment, step S63 further includes: tensioning with a steel cable, the steel cable being connected to an oil pump, the oil pump being started to supply oil and pressurize, and when the pressure reaches the design tension of the steel cable, the pressurization is stopped when the tension is over-tensioned by 2% to 4%, thus completing the prestressed steel cable tensioning.

[0031] Compared with existing technologies, the prestressed steel tie rod and its tensioning construction method for a cantilever platform of a building according to embodiments of the present invention have the following advantages:

[0032] The prestressed steel tie rods and their hoisting construction method for cantilever platforms in this invention include multiple steel tie rod segments. Adjacent steel tie rod segments are connected by sleeves. A first fastening nut structure is installed at the end of the steel tie rod segment along the straight edge, and a second fastening nut structure is installed at the end of at least one steel tie rod segment in the middle of the straight section. The second fastening nut structure is fitted snugly against the sleeve. During tensioning, tensioning anchors are used to tension the steel tie rods, with each tensioning session lasting at least one minute. After each tensioning session, the tensioning anchors are used to fix the tension rods. This application, by setting prestressed steel tie rods in the core tube shear wall, offsets the residual tensile force of the cantilever platform load on the concrete structure, minimizing the possibility of concrete cracking due to tension and ensuring structural construction safety. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the prestressed steel tie rod of the cantilever platform in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the tensioning method in the construction method for hoisting prestressed steel tie rods of a cantilevered platform according to an embodiment of the present invention.

[0035] In the diagram, 1. Steel tie rod segment, 2. Sleeve, 4. First fastening nut structure, 5. Second fastening nut structure, 6. Steel tie rod anchor, 7. Lower truss, 8. Core tube shear wall, 9. Upper truss, 10. Support frame, 11. Jack, 12. Tensioning anchor, 13. Extension rod. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0037] Among them, such as Figure 1As shown in the embodiment of the present invention, the prestressed steel tie rod for the cantilever platform of a super high-rise building includes steel tie rod segments 1, multiple steel tie rod segments 1 arranged in a straight line; sleeves 2, with internal threads at both ends of the sleeves 2, and the ends of two adjacent steel tie rod segments 1 are respectively installed in the internal threads; specifically, since the steel tie rods are installed on the stiffening plates in two steel columns, to ensure smooth welding, the position of the steel tie rod segments 1 needs to be 500mm below the position of the steel column segments. At the same time, if the length of the steel tie rod is too large, it will affect the installation and lifting. Therefore, the maximum length of the steel tie rod segments 1 is finally determined to be 6m. The length of the steel tie rods in this project is 42m, so each group of steel tie rods is divided into 9 segments, with the longest segment being 6m. The segments are connected by connecting sleeves 2. The thread length of the connecting sleeves 2 meets the minimum anchorage length requirement.

[0038] Meanwhile, to increase the straight edge of the steel tie rod segment 1, a first fastening nut structure 4 is installed at the end of the steel tie rod segment 1, and a second fastening nut structure 5 is installed at the end of at least one steel tie rod segment 1 in the middle of the straight line. The second fastening nut structure 5 is fitted and installed in close contact with the sleeve 2.

[0039] In a specific embodiment of this application, the end of the steel tie rod segment 1 is provided with an external thread, which is matched and installed with the internal thread of the sleeve 2; both the first fastening nut structure 4 and the second fastening nut structure 5 include a thick nut and a thin nut that are sequentially threaded onto the external thread. The thick nut and the thin nut are used to further fix the sleeve 2 and the steel tie rod segment 1.

[0040] In a specific embodiment of this application, the steel tie rod is also provided with threads for connecting the core tube shear wall 8.

[0041] In this application, the minimum clearance between the sleeve 2 and the steel pull rod is 25mm, and a chain wrench with a chain thickness of less than 25mm is selected to tighten the sleeve 2. The connecting sleeve 2 has a double-threaded design, allowing the steel pull rods at both ends of the sleeve 2 to move in and out simultaneously. Each connecting sleeve 2 has a certain adjustment margin. The rods are ±44mm and ±34mm respectively, which can adjust for installation errors in the structure. During adjustment, attention should be paid to the minimum anchorage length requirement of the steel tie rod; the thread length of the steel tie rod entering the adjusting sleeve 2 must meet the following requirements. The rod should be no less than 108mm. The rod should be no less than 68mm, and this requirement should be met at both ends of sleeve 2. After sleeve 2 is installed, to prevent it from loosening during upper-level installation, sleeve 2 and the steel tie rod should be spot-welded, with three to four spot welds on each side of sleeve 2. During steel tie rod installation, the adjustment amount of sleeve 2 should be adjusted according to the height deviation of each layer of the structure to compensate for the structural deviation.

[0042] To improve structural stress and prevent tensile cracking of the core tube concrete during construction, this application incorporates prestressed steel tie rods, as described in this embodiment, arranged within the core tube and on the roof truss. The prestressed steel tie rods are installed within the FT38-1 truss core tube and include… Two types. The steel tie rod arrangement height is from the 30th to the 38th floor. In the four steel columns within the core tube wall at axes 8-10, one prestressed steel tie rod is arranged on each side of the web of each H-shaped steel column. The prestressed steel tie rods are high-strength anchor rods of strength grade 650, totaling four rods. Steel tie rod and 4 The steel tie rod is approximately 42m in length; prestress is applied to the structure by tensioning the steel tie rod to improve the stress state of the cantilever truss structure. The tension of the steel tie rod is 600 kN / rod. The tension value of the steel tie rod is 1500kN / rod.

[0043] An embodiment of a construction method for prestressed steel tie rods on a cantilevered building platform is provided. Specifically, due to the numerous and interconnected construction steps involved in steel structure tie rod construction, including steel column installation, steel tie rod installation, grouting duct welding, concrete reinforcement binding, and concrete pouring, the construction of tie rods and steel components requires close coordination to ensure the safety and quality of the structural construction and to meet the requirements of the structural design.

[0044] Specifically, the construction method for the prestressed steel tie rod of the cantilever platform in this application includes the following steps:

[0045] S1, Install H-shaped steel columns; In practice, since the installation of steel tie rods will affect the welding of steel frame, steel columns need to be installed first in each section, and then steel tie rods need to be installed.

[0046] S2, steel plates are welded to the edges of the H-shaped steel columns to seal the internal space of the H-shaped steel columns, forming grouting channels, which are then filled with grout. Specifically, the grouting channels are welded from steel plates. Since their installation would affect the installation of the steel tie rods, the steel tie rods must be installed first before welding the grouting channels.

[0047] S3, construct the core tube shear wall 8; tie the concrete reinforcement of the core tube shear wall 8, and pour the core tube concrete; the concrete reinforcement outside the steel tie rod will affect the installation of the steel tie rod and grouting duct, so it needs to be tied last.

[0048] S4, connect the first steel tie rod segment 1 to the lower part of the core tube shear wall 8 through anchorage; connect the first steel tie rod segment 1 to the stiffening plate of the core tube shear wall 8 through bolts of anchorage.

[0049] Furthermore, during the specific installation, the steel tie rods are vertically hoisted one by one using a tower crane. The steel tie rods weigh 350kg and 150kg respectively. The steel tie rods are hoisted to position 8 of the core tube shear wall. The hoisting process includes at least two hoisting connectors, which connect the threads of the steel tie rod and the threads of the sleeve 2, respectively. Whether the connecting sleeve 2 is hoisted together depends on whether it needs to pass through the stiffening rib holes.

[0050] S5, repeat steps S2 to S3, connect the second steel tie rod segment 1 to the first steel tie rod segment 1 through sleeve 2, and repeat step S4;

[0051] S6, such as Figure 2 As shown, tensioning is carried out on section 1 of the installed steel tie rod; after the grouting concrete reaches 95% strength, the steel tie rod is tensioned.

[0052] In a specific embodiment of this application, the tensioning equipment uses tooling made with a corresponding jack 11 and a matching oil pump. The jack 11 and oil pump are calibrated according to the actual tension force required by the design and prestressing process. In actual use, the value corresponding to the control tension force is found on this calibration curve and marked on the corresponding pump top label for easy operation and inspection.

[0053] The tensioning of prestressed steel tie rods adopts a dual-control approach, with the tension force of the prestressed steel tie rod as the primary control and the elongation value as the secondary control. Measurement and calibration should be performed immediately after the prestressed steel tie rod tensioning is completed.

[0054] Specifically, S61, steel tie rod anchor 6 is installed and initially pre-tightened, exposing the threads;

[0055] S62, connect the extension rod 13 to the threaded connection, install the steel tie rod anchor 6 on the lower truss 7, so that the extension rod 13 extends to the top of the upper truss 9, and install the load-bearing frame 10, jack 11 and tensioning anchor in sequence on the extension rod 13 at the top of the upper truss 9; the extension rod 13, load-bearing frame 10, jack 11 and tensioning anchor should be arranged concentrically, and since there are many tensioning equipment components, the centroid of the tensioning equipment must be aligned with the steel cable during installation to ensure that the prestressed steel cable does not become eccentric during tensioning;

[0056] S63. Use tensioning anchors to tension the steel tie rods. Each tensioning session should last at least 1 minute. After each tensioning session, secure the tie rod with the tensioning anchors. During tensioning, control the oil supply rate; the oil supply time should not be less than 0.5 minutes. After the prestressed steel tie rods are tensioned, perform measurements and calibration. After all tensioning is completed, tighten the nuts to prevent loosening later.

[0057] Specifically, tensioning is achieved using steel cables connected to an oil pump. The oil pump is activated to supply oil and apply pressure. When the pressure reaches the design tension of the steel cable, and the tension is over-tensioned by 2% to 4%, pressurization is stopped, completing the prestressed steel cable tensioning. Further, pressurization is stopped when the tension is over-tensioned by 3%.

[0058] Meanwhile, in specific implementation, there are also certain requirements for the tensioning platform: a tensioning platform must be erected at the tensioning end of the tie rod, with a platform width of not less than 1.5m, a height range of 1.0m to 1.5m from the tensioning point, and a load-bearing capacity of not less than 350kg / m. The platform must be fully covered with scaffold boards, and the bottom surface must be covered with dense mesh netting and safety netting. The uprights and horizontal bars of the scaffolding must avoid the location of the tie rod.

[0059] The construction method for the prestressed steel tie rods of the cantilever platform in this application is as follows: installation of the lower steel columns → welding of horizontal stiffening plates (with openings in the plates) between the steel columns → installation of the lowest steel tie rod on the stiffening plate, positioning, and anchoring with high-strength bolts → installation of the upper layer steel columns → installation and connection of the upper layer steel tie rods → welding and sealing of grouting ducts → binding of reinforcing bars → continued construction of the upper layer steel columns and steel tie rods until the construction is completed.

[0060] For example, the tension force and tension value requirements for the construction method of the prestressed steel tie rod of the cantilever platform in this application are as follows: According to the design requirements, The rod has a 100% tension of 1500 kN. The 100% tension of the rod is 600 kN. Over-tensioning is 3%, and the tensioning process is divided into five levels: 20%, 40%, 60%, 80%, and 103%. The corresponding tension for each level is shown in Table 1 (unit: kN).

[0061]

[0062] Table 1. Grading Table of Tension Force Values

[0063] According to the specifications, the allowable deviation of the tension force is ±10%, therefore the allowable range of the cable force after tensioning is 93% to 113%. The elongation of the steel tie rod was measured during the tensioning process; the elongation data are shown in Table 2.

[0064]

[0065] Table 2. Elongation Value Grading Table

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A prestressed steel tie rod for a cantilevered building platform, characterized in that, include: The steel tie rod is segmented, and multiple steel tie rod segments are arranged in a straight line sequentially. A sleeve, with internal threads at both ends of the sleeve, and the two ends of two adjacent steel tie rod segments are respectively installed in the internal threads; A first fastening nut structure is installed at the end of the steel tie rod segment along the straight edge, and a second fastening nut structure is installed at the end of at least one steel tie rod segment in the middle of the straight line. The second fastening nut structure is fitted into the sleeve. The ends of the steel tie rod segments are provided with external threads, which are matched and installed with the internal threads of the sleeve; Both the first fastening nut structure and the second fastening nut structure include a thick nut and a thin nut that are sequentially threaded onto the external thread; The sleeve has a double-threaded design so that the steel tie rods at both ends of the sleeve can move in and out simultaneously. The thread length of the sleeve meets the minimum anchorage length requirement; The sleeve has an adjustment margin to accommodate installation errors in the structure.

2. The prestressed steel tie rod for a cantilevered building platform according to claim 1, characterized in that: The steel tie rod is also equipped with threads for connecting to the core tube shear wall.

3. A construction method for the prestressed steel tie rod of a cantilevered platform as described in claim 1, characterized in that, include: S1, Install H-beam steel columns; S2, steel plates are welded to the edges of the H-shaped steel column to seal the internal space of the H-shaped steel column, forming grouting channels, and grouting is performed on the grouting channels; S3, construction core tube shear wall; S4, the first steel tie rod segment is connected to the lower part of the core tube shear wall through anchorage; S5. Repeat steps S2 to S3 to connect the second steel tie rod segment to the first steel tie rod segment using a sleeve. Repeat step S4. When installing steel tie rods, adjust the adjustment amount of the adjusting sleeve according to the height deviation of each layer of the structure to compensate for the structural deviation; S6, Perform tensioning work on the installed steel tie rods in sections; S61, steel tie rod anchorage installed and initially pre-tightened, exposing the threads; S62, connect the extension rod to the threaded connection so that the extension rod extends to the top of the upper truss, and install the load-bearing frame, jack and tensioning anchor in sequence on the extension rod at the top of the upper truss; Extension rods, support frames, jacks, and tensioning anchors should be arranged concentrically; S63. Use tensioning anchors to tension the steel tie rods. Each tensioning time shall be greater than or equal to 1 minute. After each tensioning is completed, use tensioning anchors to fix the tension rods. The tensioning of prestressed steel tie rods adopts dual control, with the tension force of the prestressed steel tie rod as the main control and the elongation value as the auxiliary control.

4. The construction method of the prestressed steel tie rod for a cantilevered building platform as described in claim 3, characterized in that, Step S3 further includes: tying the concrete reinforcement of the core tube shear wall and pouring the core tube concrete; Step S4 further includes: connecting the first steel tie rod segment to the stiffening plate of the core tube shear wall through anchor bolts.

5. The construction method of the prestressed steel tie rod for a cantilevered building platform as described in claim 3, characterized in that, Step S4 further includes: hoisting the steel tie rod to the core tube shear wall. The hoisting construction includes at least two hoisting connectors, and the two hoisting connectors are respectively connected to the threads of the steel tie rod and the threads of the sleeve.

6. The construction method of the prestressed steel tie rod for a cantilevered building platform as described in claim 3, characterized in that, Step S6 further includes: tensioning the steel tie rod after the concrete to be grouted reaches 95% strength.

7. The construction method of the prestressed steel tie rod for a cantilevered building platform as described in claim 3, characterized in that, Step S63 further includes: During tensioning, the oil supply rate should be controlled, and the oil supply time should not be less than 0.5 minutes; After the prestressed steel tie rods are tensioned, measurements and calibrations are performed.

8. The construction method of the prestressed steel tie rod for a cantilevered building platform as described in claim 3, characterized in that, Step S63 further includes: tensioning with a steel cable, the steel cable being connected to an oil pump, the oil pump being started to supply oil and pressurize, and when the pressure reaches the design tension of the steel cable, the pressurization is stopped when the tension is over-tensioned by 2% to 4%, thus completing the prestressed steel cable tensioning.

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