A reverse construction method for frame columns subjected to alternating tension and compression forces

Abstract

The present invention provides a reverse construction method for frame columns that are subjected to alternating tension and compression forces, and relates to the technical field of frame column construction. The frame columns are constructed using the reverse construction method, and by reserving frame column reinforcement and connecting steel plates, other layer structures are constructed first, and the frame beam reinforcement is rationally configured to serve as a temporary cantilever beam. After the main structure forms an overall force-bearing system and the deformation is stable, the frame column is constructed. The present invention effectively avoids the risks of fracture and damage of the frame column due to the huge tension in the early stage and buckling and instability due to the huge pressure in the later stage, effectively reduces the additional pressure transmitted to the bottom steel beam of the frame column, and further improves the structural safety redundancy. The present invention does not require the addition of temporary supports, making construction more convenient and more cost-effective. At the same time, it avoids the risk of cracking of the beams and slabs connected to the frame columns, and has universal applicability and economy in solving the complex force and deformation problems of the vertical components of the main structure.

Description

Technical Field

[0001] The invention relates to the technical field of frame column construction, in particular to a reverse construction method for frame columns subjected to alternating tension and compression forces. Background Art

[0002] Since the beginning of this century, with the rapid development of my country's construction industry, large-span, high-headroom buildings have become increasingly prevalent, placing high demands on the mechanical properties and construction techniques of complex structures. Conventional construction methods for building frame columns are sequentially constructed from bottom to top, layer by layer. As the load is applied layer by layer, the frame columns experience increasing pressure and remain in a constant state of compression, consistent with the mechanical properties of their materials. However, the conventional sequential construction method fails to meet the technical requirements for horizontal components such as beams and slabs connected to the top and bottom ends of the frame columns, which experience significant differential deformations that dynamically change with layer-by-layer loading. During construction, the top and bottom ends of the frame columns, constrained by the horizontal components, experience a conversion between tension and compression. Initially, the deformation at the top of the frame column is smaller than at the base, resulting in the column bearing significant tensile forces, causing the steel bars to yield and develop horizontal cracks. Later, as the layer-by-layer loading is completed, the deformation at the top of the frame column exceeds the deformation at the base, causing the column to experience significant compressive stress, leading to buckling instability. This pressure is then transmitted downward, placing additional stress on the steel beams at the column base. Therefore, it is particularly important to choose an appropriate construction method to avoid the influence of tension-compression conversion of internal forces in frame columns, reduce additional pressure, ensure project quality and facilitate construction. Summary of the Invention

[0003] In response to the above-mentioned existing technologies, the present invention proposes a reverse construction method for frame columns subjected to alternating tension and compression forces, aiming to solve quality problems such as damage to the main structure caused by the change in the stress state of the frame columns caused by phased construction conditions, and can effectively improve the safety redundancy of the main structure.

[0004] The present invention provides a reverse construction method for frame columns subjected to alternating tension and compression forces, assuming that the frame columns are located between the Fth floor and the F+1th floor, comprising the following steps:

[0005] Step 1, F-layer structure construction: hoisting of the F-layer steel structure, erection of the support frame and formwork, welding of the reserved connection steel plates on the upper flange of the F-layer steel beam corresponding to the bottom of the frame column, tying of steel bars and pouring of concrete;

[0006] Step 2: F+1 layer structure construction: Install temporary support facilities for the F+1 layer transfer beams that coordinate the deformation of the frame column tops through the frame beams, hoist the F+1 layer rigid structural steel, erect the support frame and formwork, tie the steel bars, disconnect the bottom ends of the frame column longitudinal bars from the F layer connecting steel plates, and set the F+1 layer frame beam steel bars connected to the frame column tops according to the larger value of the original design and the temporary cantilever force envelope, and complete the concrete pouring outside the frame columns;

[0007] Step 3: Carry out structural construction from F+2 to F+4 floors in sequence: hoist the rigid structural steel, erect the support frame and formwork, tie the steel bars, and pour concrete.

[0008] Step 4: The structures of the F+1 and F layers are fully stressed and deformed in a coordinated manner: When the concrete strength of the F+1 and F layers reaches the design value, except for the temporary support facilities of the F+1 layer transfer beam that coordinates the deformation of the frame column top, the support frames and formwork of the F+1 and F layers are removed from top to bottom, so that the horizontal components such as the beams and slabs of the F+1 and F layers can be fully stressed under the action of the structure's deadweight and construction live loads. The downward deformation value of the F+1 layer transfer beam that coordinates the deformation of the frame column top is S1, and the downward deformation value of the F layer steel beam corresponding to the frame column bottom is S2;

[0009] Step 5: Construction of the structures from the F+5th to the F+nth floors shall be carried out in sequence: the structural steel hoisting, support frame and formwork erection, reinforcement binding and concrete pouring shall be carried out in sequence. During this period, the support frame and formwork below each floor shall be removed in sequence from the F+2th floor to the F+nth floor, provided that the concrete strength of the floor structure reaches the design value.

[0010] Step 6: Formation of the overall spatial structural force system from the F+1th to the F+nth floors: After the structural concrete strength of the F+nth floor reaches the design value and the supporting frame and formwork underneath are removed, thus forming the overall spatial structural force system from the F+1th to the F+nth floors, remove the temporary support facilities of the transfer beam on the F+1th floor that coordinates the deformation of the frame column tops;

[0011] Step 7: The structures from the F+1th to the F+nth floors are left stationary for internal force redistribution: The structures from the F+1th to the F+nth floors are left stationary for internal force redistribution until the horizontal components such as beams and slabs on each floor are deformed to a stable state, and the downward deformation value of the conversion beam that coordinates the deformation of the frame column top on the F+1th floor is S3;

[0012] Step 8. Construction of the frame column structure between the Fth floor and the F+1th floor: weld the bottom end of the longitudinal reinforcement of the frame column to the connecting steel plate of the Fth floor, set up the formwork, pour the concrete of the frame column, and remove the formwork after the concrete strength of the frame column reaches the design value.

[0013] Preferably, the connecting steel plates described in steps 1, 2, and 8 are made of Q345B or Q355B steel, with a height ≥ 5d + h + ∆S, a width of d + 30 mm, and a thickness of d; where d is the diameter of the longitudinal reinforcement of the frame column, h is the thickness of the reinforced concrete floor slab of the Fth layer, and ∆S is the maximum value of the deformation difference between the top and bottom of the frame column.

[0014] Preferably, the temporary support facilities described in steps 2, 4 and 6 are sand boxes or jacks.

[0015] Preferably, the deformation values ​​in steps 4 and 7 should satisfy S2-S1≥3mm or S3-S2≥3mm.

[0016] Preferably, the design values ​​described in steps 4, 5, 6 and 8 are all determined by using the 28-day pressure strength report of the test blocks cured under the same conditions to determine whether the concrete strength reaches 100% of the design strength.

[0017] Preferably, the bottom end of the longitudinal reinforcement of the frame column described in step eight is welded to the F-th layer connecting steel plate using double-sided welding 5d, where d is the diameter of the longitudinal reinforcement of the frame column.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention adopts the reverse construction method to construct the frame columns during the main structure construction process, so that the horizontal components such as beams and slabs connected to the top and bottom ends of the frame columns are allowed to deform independently to a stable state, avoiding the alternating tension and compression stresses of the frame columns due to the deformation difference between the top and bottom ends, thereby solving the hidden dangers of frame column fracture, damage, buckling instability, etc.; at the same time, it effectively reduces the additional pressure transmitted to the steel beams at the bottom of the frame columns, and improves the structural safety redundancy.

[0020] 2. The present invention adopts the principle of taking the maximum value of the envelope to adjust the reinforcement of the frame beam so that it can not only meet the original design requirements but also serve as a temporary cantilever beam, avoiding the risk of beam and slab cracking due to insufficient force on the frame beam during construction, and eliminating the need to add temporary supports to horizontal components such as beams and slabs, thereby reducing construction difficulty and measures costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a construction process flow and pre-condition process diagram of an embodiment of the present invention.

[0022] Figure 2 It is a structural diagram of the F-th floor when the construction is completed in the embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the node structure when the upper flange of the F-th layer steel beam corresponding to the bottom of the frame column of an embodiment of the present invention is completed by welding the reserved connecting steel plate.

[0024] Figure 4 It is a structural diagram of the F+1 layer when construction is completed in an embodiment of the present invention.

[0025] Figure 5 Schematic diagram of the node structure when the bottom end of the longitudinal reinforcement of the frame column and the F-th layer connecting steel plate are welded.

[0026] Figure 6This is a schematic diagram of the structure when the construction of the F+2 to F+4 floors is completed in an embodiment of the present invention.

[0027] Figure 7 It is a structural diagram of an embodiment of the present invention when the construction of the F+5th to F+nth floors is completed.

[0028] Figure 8 This is a structural schematic diagram of the embodiment of the present invention after the sand box of the temporary support facility of the conversion beam for coordinating the deformation of the frame column top on the F+1 floor is dismantled.

[0029] Figure 9 This is a schematic structural diagram of the embodiment of the present invention when the concrete pouring of the frame columns from the Fth floor to the F+1th floor is completed.

[0030] In the attached figure: 1—frame column; 2—F-th floor steel beam; 3—connecting steel plate; 4—F+1-th floor transfer beam; 5—F+1-th floor frame beam; 6—sand box; 7—F-th floor reinforced concrete floor slab; 8—frame column longitudinal reinforcement. DETAILED DESCRIPTION

[0031] In order to better understand the technical means, creative features, objectives and effects achieved by the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0032] In the description of the present invention, it should be noted that the positional relationships indicated by terms such as “top”, “bottom”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” cited in this specification are based on the positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0033] like Figures 1-9 As shown, this embodiment provides a reverse construction method for frame columns subjected to alternating tension and compression forces, wherein the frame column 1 is located between the Fth floor and the F+1th floor, comprising the following steps:

[0034] Step 1: Construction of the F-layer structure: Figure 2 and Figure 3As shown, the F-th floor steel structure is hoisted, the supporting frame and formwork are erected, and the upper flange of the F-th floor steel beam 2 corresponding to the bottom of the frame column 1 is reserved by welding a connecting steel plate 3; the number of connecting steel plates 3 is the same as the number of frame column longitudinal reinforcement 8, and Q345B steel is used, with a height ≥5d+h+∆S, a width of d+30mm, and a thickness of d; where d is the diameter of the frame column 1 longitudinal reinforcement 8, h is the thickness of the F-th floor reinforced concrete slab 7, and ∆S is the maximum difference in deformation between the top and bottom of the frame column 1; the reinforcement is tied and the concrete is poured.

[0035] Step 2: Construction of the F+1 layer structure: Figure 4 As shown, the F+1 layer transfer beam 4 that coordinates the deformation of the frame column 1 top is installed with the frame beam 5, and the temporary supporting facility sand box 6 is installed. The F+1 layer rigid structural steel is hoisted, the supporting frame and formwork are erected, the steel bars are tied, and the bottom end of the frame column longitudinal reinforcement 8 is disconnected from the connecting steel plate 3 of the F layer. The steel bars of the F+1 layer frame beam 5 connected to the top of the frame column 1 are set according to the original design and the larger value of the temporary cantilever force envelope, and the concrete pouring outside the frame column 1 is completed.

[0036] Step 3: Follow the steps to construct the F+2 to F+4 layers: Figure 6 As shown, the structural construction of the F+2 to F+4 floors was completed in the order of hoisting the rigid structural steel, erecting the support frame and formwork, tying the steel bars and pouring the concrete.

[0037] Step 4: The structures of the F+1 and F layers are fully stressed and deformed in a coordinated manner: When the concrete strength of the F+1 and F layers reaches the design value, except for the F+1 layer transfer beam 4 that coordinates the deformation of the frame column 1, which retains the temporary support facility sand box 6, the support frames and formwork of the F+1 and F layers are removed from top to bottom, so that the horizontal components such as the beams and slabs of the F+1 and F layers can be fully stressed under the action of the structure's deadweight and construction live loads; the F+1 layer frame beam 5 connected to the top of the frame column 1 forms a temporary suspension The arm beam deforms cooperatively with the F+1th layer transfer beam 4, avoiding the risk of beam and slab cracking due to insufficient force through cantilever bearing, and no temporary support is required, reducing construction difficulty and measures costs; the downward deformation value of the F+1th layer transfer beam 4 that coordinates the deformation of the top of the frame column 1 is S1=3.2mm, so that the downward deformation value of the F+1th layer frame beam 5 and the top of the frame column 1 is S1=3.2mm, and the downward deformation value of the F+1th layer steel beam 2 corresponding to the bottom of the frame column 1 is S2=10.6mm.

[0038] Step 5: Follow the steps to construct the structures from F+5th to F+nth layers: Figure 7As shown, the structural construction of the F+5th to F+nth floors was completed in the order of hoisting the rigid structural steel, erecting the support frame and formwork, tying the steel bars and pouring the concrete. During this period, on the premise that the concrete strength of the floor structure reached the design value, the support frame and formwork below the floor were removed in sequence from the F+2th floor to the F+nth floor.

[0039] In this embodiment, the F+nth layer is the roofing layer.

[0040] Step 6: Formation of the overall spatial structural force system from the F+1st floor to the F+nth floor: After the concrete strength of the F+nth floor structure reaches the design value and the supporting frame and formwork below it are removed, thus forming the overall spatial structural force system from the F+1st floor to the F+nth floor, remove the temporary supporting facility sand box 6 of the F+1st floor transfer beam 4 that is deformed at the top of the F+1st floor coordination frame column 1, as shown in the following figure: Figure 8 As shown, the F+1th to F+nth floors are transformed from a temporary support force system to a self-supporting force system.

[0041] Step seven, the structures from the F+1th to the F+nth floors are left stationary for internal force redistribution: the structures from the F+1th to the F+nth floors are left stationary for internal force redistribution until the horizontal components such as beams and slabs on each floor are deformed to a stable state; the downward deformation value of the F+1th floor transfer beam 4 that coordinates the deformation of the top of the frame column 1 on the F+1th floor is S3=16.9mm, so that the downward deformation value of the F+1th floor frame beam 5 and the top of the frame column 1 is S3=16.9mm. At this point, the deformation of the top and bottom of the frame column 1 during the construction process has reached a stable state.

[0042] Step 8: Construction of frame column structure between Fth floor and F+1th floor: Figure 5 As shown, the bottom end of the frame column longitudinal reinforcement 8 is welded to the connecting steel plate 3 of the F layer, using double-sided welding 5d, where d is the diameter of the frame column longitudinal reinforcement 8; the formwork is erected, and the concrete of the frame column 1 is poured. The formwork is removed after the concrete strength of the frame column 1 reaches the design value, as shown in FIG. Figure 9 shown.

[0043] The deformation values ​​in steps 4 and 7 satisfy S2-S1=10.6mm-3.2mm=7.4mm≥3mm and S3-S2=16.9mm-10.6mm=6.3mm≥3mm.

[0044] The design values ​​described in steps 4, 5, 6, and 8 all use the 28-day compressive strength report of the test blocks cured under the same conditions to determine whether the concrete strength has reached 100% of the design strength.

[0045] The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the guidance of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A reverse construction method for frame columns subjected to alternating tension and compression forces, characterized in that: Assuming that the frame column is located between the Fth floor and the F+1th floor, the following steps are included: Step 1, F-layer structure construction: hoisting of the F-layer steel structure, erection of the support frame and formwork, welding of the reserved connection steel plates on the upper flange of the F-layer steel beam corresponding to the bottom of the frame column, tying of steel bars and pouring of concrete; Step 2: F+1 layer structure construction: Install temporary support facilities for the F+1 layer transfer beams that coordinate the deformation of the frame column tops through the frame beams, hoist the F+1 layer rigid structural steel, erect the support frame and formwork, tie the steel bars, disconnect the bottom ends of the frame column longitudinal bars from the F layer connecting steel plates, and set the F+1 layer frame beam steel bars connected to the frame column tops according to the larger value of the original design and the temporary cantilever force envelope, and complete the concrete pouring outside the frame columns; Step 3: Carry out structural construction from F+2 to F+4 floors in sequence: hoist the rigid structural steel, erect the support frame and formwork, tie the steel bars, and pour concrete. Step 4: The structures of the F+1 and F layers are fully stressed and deformed in a coordinated manner: When the concrete strength of the F+1 and F layers reaches the design value, except for the temporary support facilities of the F+1 layer transfer beam that coordinates the deformation of the frame column top, the support frames and formwork of the F+1 and F layers are removed from top to bottom, so that the beams and slabs of the F+1 and F layers can be fully stressed under the action of the structure's deadweight and construction live loads. The downward deformation value of the F+1 layer transfer beam that coordinates the deformation of the frame column top is S1, and the downward deformation value of the F layer steel beam corresponding to the frame column bottom is S2; Step 5: Construction of the structures from the F+5th to the F+nth floors shall be carried out in sequence: the structural steel hoisting, support frame and formwork erection, reinforcement binding and concrete pouring shall be carried out in sequence. During this period, the support frame and formwork below each floor shall be removed in sequence from the F+2th floor to the F+nth floor, provided that the concrete strength of the floor structure reaches the design value. Step 6: Formation of the overall spatial structural force system from the F+1th to the F+nth floors: After the structural concrete strength of the F+nth floor reaches the design value and the supporting frame and formwork underneath are removed, thus forming the overall spatial structural force system from the F+1th to the F+nth floors, remove the temporary support facilities of the transfer beam on the F+1th floor that coordinates the deformation of the frame column tops; Step 7: The structures from the F+1th to the F+nth floors are left stationary for internal force redistribution: The structures from the F+1th to the F+nth floors are left stationary for internal force redistribution until the beams and slabs of each floor are deformed to a stable state, and the downward deformation value of the conversion beam that coordinates the deformation of the frame column top on the F+1th floor is S3; Step 8. Construction of the frame column structure between the Fth floor and the F+1th floor: weld the bottom end of the longitudinal reinforcement of the frame column to the connecting steel plate of the Fth floor, set up the formwork, pour the concrete of the frame column, and remove the formwork after the concrete strength of the frame column reaches the design value.

2. The reverse construction method for frame columns subjected to alternating tension and compression as claimed in claim 1, characterized in that: The connecting steel plates described in steps 1, 2, and 8 are made of Q345B or Q355B steel, with a height ≥ 5d + h + ∆S, a width of d + 30mm, and a thickness of d. d is the diameter of the longitudinal reinforcement of the frame column, h is the thickness of the reinforced concrete floor slab of the Fth layer, and ∆S is the maximum difference in deformation between the top and bottom of the frame column.

3. The reverse construction method for frame columns subjected to alternating tension and compression forces according to claim 1 or 2, characterized in that: The temporary support facilities described in steps 2, 4 and 6 are sand boxes or jacks.

4. The reverse construction method for frame columns subjected to alternating tension and compression forces according to claim 1 or 2, characterized in that: The deformation values ​​described in steps 4 and 7 should satisfy S2-S1≥3mm or S3-S2≥3mm.

5. The reverse construction method for frame columns subjected to alternating tension and compression forces according to claim 1 or 2, characterized in that: The design values ​​described in steps 4, 5, 6, and 8 all use the 28-day compressive strength report of the test blocks cured under the same conditions to determine whether the concrete strength has reached 100% of the design strength.

6. The reverse construction method for frame columns subjected to alternating tension and compression forces according to claim 1 or 2, characterized in that: The welding between the bottom end of the longitudinal reinforcement of the frame column and the F-th layer connecting steel plate is carried out by double-sided welding 5d, where d is the diameter of the longitudinal reinforcement of the frame column.

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