Comb-tooth column stirrup structure and calculation method of shear resistance provided by comb teeth

Abstract

The present invention discloses a comb-tooth column stirrup structure and a method for calculating the shear resistance provided by the comb teeth, comprising a plurality of outer ring closed stirrups uniformly distributed along the length direction of the column and in a circular shape matching the cross-sectional shape of the column, and a plurality of longitudinal stress-bearing steel bars parallel to the length direction of the column, surrounding and tightly attached to the inner side of each outer ring closed stirrup; each outer ring closed stirrup is provided with a plurality of comb-tooth anchoring steel bars extending inward; one side of each comb-tooth anchoring steel bar is provided with longitudinal stress-bearing steel bars, the extension direction of which is within the plane formed by the corresponding outer ring closed stirrups, and one end extending into the inner side of the corresponding outer ring closed stirrup has a bending structure with an angle of less than 90 degrees as an anchoring end; the opening direction of each bending structure is toward the outer side of the corresponding outer ring closed stirrup. The shear resistance V of each comb-tooth anchoring steel bar ds =(l0 / 25d)*V s The application of the present invention reduces a large number of closed stirrups and can save a large amount of labor.

Description

Technical Field

[0001] The invention relates to the technical field of column prefabrication, and in particular to a comb-tooth type column stirrup structure and a method for calculating the shear resistance provided by the comb teeth. Background Art

[0002] The column structure is subjected to axial compression and eccentric compressive loads during use. In order to realize the restraining effect of stirrups on the core concrete of the column, prevent the yielding of the longitudinal reinforcement, and improve the shear capacity of the column, the column stirrups are usually arranged as closed stirrups or even composite closed stirrups.

[0003] However, this stirrup arrangement method brings troubles to the stirrup binding at the factory end, especially for large column structures. Each closed stirrup needs to be opened by workers by hand and put on the corresponding longitudinal steel bar, which takes a lot of man-hours.

[0004] Therefore, how to optimize the structure of the stirrups while meeting the stress requirements to facilitate on-site operation by workers has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a comb-tooth column stirrup structure and a method for calculating the shear resistance provided by the comb teeth, the purpose of which is to optimize the steel bar structure, reduce the difficulty of on-site stirrup tying, save labor hours, and improve the economy of column construction.

[0006] To achieve the above-mentioned purpose, the present invention discloses a comb-tooth column stirrup structure, including a plurality of outer ring closed stirrups evenly distributed along the length direction of the column and having a ring-shaped shape matching the cross-sectional shape of the column, and a plurality of longitudinal force-bearing steel bars parallel to the length direction of the column, surrounding and tightly attached to the inner side of each outer ring closed stirrup.

[0007] Each of the outer ring closed stirrups is provided with a plurality of comb-tooth anchoring steel bars extending inwards;

[0008] One side of each of the comb-tooth anchoring steel bars is provided with longitudinal force-bearing steel bars, the extending direction of which is in the plane formed by the corresponding outer ring closed stirrups, and one end extending into the inner side of the corresponding outer ring closed stirrups has a bending structure with an angle less than 90 degrees as an anchoring end;

[0009] The plane formed by each of the bending structures is perpendicular to the plane formed by the corresponding outer ring closed stirrups, and the opening direction is toward the outside of the corresponding outer ring closed stirrups.

[0010] Preferably, each of the outer ring closed stirrups is a closed annular structure, and its shape is circular, oblong, elliptical or convex polygonal matching the cross-section of the corresponding column.

[0011] Preferably, each of the outer ring closed stirrups is connected to all the comb-tooth anchor steel bars by connecting a plurality of U-shaped restraining steel bars with the comb-tooth anchor steel bars;

[0012] Each of the U-shaped restraining steel bars includes two comb-tooth anchoring steel bars and a connecting portion arranged between the two comb-tooth anchoring steel bars and connected to the corresponding outer ring closed stirrups.

[0013] More preferably, two or more U-shaped restraining steel bars with different connecting portion lengths are welded together to form a first assembly with an even number of comb-tooth-shaped anchoring steel bars;

[0014] Each of the first-type assemblies is fixed by a weld formed by welding between the corresponding connecting portion with the longest length and the corresponding outer ring closed stirrup.

[0015] More preferably, two or more of the U-shaped restraining steel bars with the same length of the connecting parts are fixed to the skeleton steel bars by welding to form a second assembly with an even number of the comb-tooth-shaped anchoring steel bars;

[0016] Each of the second-type assemblies is fixed by a weld formed by welding between the corresponding skeleton reinforcement and the corresponding U-shaped restraining reinforcement;

[0017] The shape of each of the skeleton reinforcement bars matches the connecting portion of the corresponding outer ring closed stirrups.

[0018] More preferably, each of the skeleton steel bars includes a bent section in the corresponding outer ring closed stirrup, which overlaps with a portion of the corresponding outer ring closed stirrup with a matching shape.

[0019] Preferably, the maximum distance between each of the longitudinal stress-bearing steel bars and the closest comb-tooth anchoring steel bar on each of the outer ring closed stirrups is less than 15 times the diameter of the corresponding comb-tooth anchoring steel bar;

[0020] The length of each of the comb-tooth anchor steel bars extending into the corresponding outer ring closed stirrups is 25 times the diameter of the corresponding comb-tooth anchor steel bar.

[0021] The present invention also provides a method for calculating the shear resistance provided by the comb teeth of the comb-tooth type column stirrup structure, comprising the following steps:

[0022] First, it is assumed that any of the comb-shaped anchor bars for which shear resistance calculation is required passes through the 45-degree shear plane;

[0023] Then, it is obtained that the shortest anchorage length l0 on both sides of the shear surface is l0 < 25d, where d is 5 times the diameter of the corresponding comb-tooth anchor steel bar;

[0024] Then, the shear resistance V that the selected comb-shaped anchor steel bar (3) can provide is ds Calculate according to the following formula:

[0025] V ds =(l0 / 25d)*V s ;

[0026]

[0027] Where Av is the total area of ​​U-shaped restraint steel bars 5 in the calculation direction, in cm 2 ;

[0028] f yh is the design value of stirrup tensile strength, in MPa;

[0029] h0 is the distance from the compression edge of the core concrete to the center of gravity of the steel bars on the tension side, in cm;

[0030] s is the spacing of the restraining steel bars 5, in cm.

[0031] Beneficial effects of the present invention:

[0032] Compared with common columns, the present invention reduces a large number of closed stirrups. When on-site workers tie steel bars, they put on the outer ring closed stirrups and then insert the comb-tooth-shaped stirrups, which can save a lot of labor.

[0033] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic structural diagram showing the connection between the outer ring closed stirrups, the longitudinal force-bearing steel bars and the comb-tooth anchor steel bars in one embodiment of the present invention is shown.

[0035] Figure 2 A schematic diagram of the outer ring closed stirrup structure in one embodiment of the present invention is shown.

[0036] Figure 3 A schematic plan view of the structure of a second assembly in one embodiment of the present invention is shown.

[0037] Figure 4 A schematic plan view of the structure of a first assembly in one embodiment of the present invention is shown.

[0038] Figure 5A schematic structural diagram of the skeleton reinforcement in one embodiment of the present invention is shown.

[0039] Figure 6 A schematic diagram of the planar structure of a U-shaped restraining steel bar in one embodiment of the present invention is shown.

[0040] Figure 7 A schematic diagram of the planar structure of two U-shaped restraining steel bars with different connection lengths in one embodiment of the present invention is shown.

[0041] Figure 8 A schematic diagram of the three-dimensional structure of a U-shaped restraining steel bar in one embodiment of the present invention is shown.

[0042] Fig. 9 A schematic diagram of the three-dimensional structure of a first assembly in one embodiment of the present invention is shown.

[0043] Fig.10 A schematic diagram of the three-dimensional structure of a second assembly in an embodiment of the present invention is shown.

[0044] Fig.11 A schematic diagram showing the distribution of a 45-degree shear surface of a column facade in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0045] Example

[0046] like Figures 1 to 10 As shown, the comb-tooth column stirrup structure includes a plurality of annular outer ring closed stirrups 2 evenly distributed along the length direction of the column and shaped to match the cross-sectional shape of the column, and a plurality of longitudinal force-bearing steel bars 1 parallel to the length direction of the column, surrounding and tightly attached to the inner side of each outer ring closed stirrup 2.

[0047] Each outer ring of closed stirrups 2 is provided with a plurality of comb-tooth anchoring steel bars 3 extending inward;

[0048] A longitudinal force-bearing steel bar 1 is provided on one side of each comb-tooth anchoring steel bar 3, and the extending direction is in the plane formed by the corresponding outer ring closed stirrup 2, and the end extending into the inner side of the corresponding outer ring closed stirrup 2 has a bending structure with an angle less than 90 degrees as an anchoring end;

[0049] The plane formed by each bending structure is perpendicular to the plane formed by the corresponding outer ring closed stirrup 2, and the opening direction is toward the outside of the corresponding outer ring closed stirrup 2.

[0050] The principle of the present invention is that, from the perspective of structural stress, the outer ring closed stirrups 2 ensure the restraint of the core concrete;

[0051] Each comb-tooth anchor steel bar is anchored deep into the core concrete, and produces a restraining effect when the outer longitudinal steel bar yields, thereby preventing the longitudinal steel bar from yielding;

[0052] When subjected to large shear force, the length of the U-shaped steel bar is extended so that the U-shaped steel bar passes through the shear surface, which can withstand part of the shear force and improve the shear resistance.

[0053] Structurally, the comb-tooth anchor bars are easy to install and can be stably placed on the outer ring closed stirrups or other comb-tooth anchor bars, ensuring that the comb-tooth anchor bars are not easily deformed when pouring concrete.

[0054] In practical applications, one end of each comb-tooth anchoring steel bar extending into the inner side of the corresponding outer ring closed stirrup 2 has a bent structure with an angle less than 90 degrees as an anchoring end, which can enhance the anchoring with the core concrete.

[0055] In some embodiments, each outer ring closed stirrup 2 is a closed annular structure, and its shape is circular, oblong, elliptical or convex polygonal matching the cross section of the corresponding column.

[0056] In some embodiments, each outer ring closed stirrup 2 is connected to all the comb-tooth anchor steel bars 3 by connecting a number of U-shaped restraining steel bars 5 with comb-tooth anchor steel bars 3;

[0057] Each U-shaped restraining steel bar 5 includes two comb-tooth anchoring steel bars 3 and a connecting portion disposed between the two comb-tooth anchoring steel bars 3 and connected to the corresponding outer ring closed stirrups 2 .

[0058] In some embodiments, two or more U-shaped restraining steel bars 5 with different connection lengths are welded together to form a first assembly with an even number of comb-tooth-shaped anchoring steel bars 3;

[0059] Each of the first type of assembled parts is fixed by a weld formed by welding between the corresponding longest connecting portion and the corresponding outer ring closed stirrup 2.

[0060] In some embodiments, two or more U-shaped restraining steel bars 5 with the same length of the connecting parts are fixed to the skeleton steel bars 4 by welding to form a second assembly with an even number of comb-shaped anchor steel bars 3;

[0061] Each second assembly is fixed by a weld formed by welding between the corresponding skeleton reinforcement 4 and the corresponding U-shaped restraining reinforcement 5;

[0062] The shape of each skeleton reinforcement 4 matches the connection portion of the corresponding outer ring closed stirrup 2 .

[0063] In some embodiments, each skeleton steel bar 4 includes a bent section in the corresponding outer ring closed stirrup 2, which is overlapped with a portion of the corresponding outer ring closed stirrup 2 that matches its shape.

[0064] In some embodiments, the maximum distance between each longitudinal force-bearing steel bar 1 and the nearest comb-tooth anchor steel bar 3 on each outer ring closed stirrup 2 is less than 15 times the diameter of the corresponding comb-tooth anchor steel bar 3;

[0065] The length of each comb-tooth anchor steel bar 3 extending into the corresponding outer ring closed stirrup 2 is 25 times the diameter of the corresponding comb-tooth anchor steel bar 3 .

[0066] For example, if the comb-tooth anchor steel bar 3 is 16 mm, the maximum distance between the longitudinal force-bearing steel bar 1 and the nearest comb-tooth anchor steel bar 3 on each outer ring closed stirrup 2 can be 215 mm, which is less than 15 times the diameter of the comb-tooth anchor steel bar 3, i.e. 240 mm.

[0067] The length of the comb-tooth anchor steel bar extending into the corresponding outer ring closed stirrup 2 is 25 times the diameter of the corresponding comb-tooth anchor steel bar 3, that is, 400 mm long.

[0068] In practical applications, when calculating the shear capacity, no comb-tooth anchor reinforcement is arranged throughout the entire cross section, and only the shear capacity of the outer ring closed stirrups 2 and the skeleton reinforcement 4 is considered.

[0069] The outer ring closed stirrup 2 calculates the total shear capacity;

[0070] like Fig.11 As shown, the present invention also provides a method for calculating the shear resistance provided by the comb teeth of the comb-tooth type column stirrup structure, comprising the following steps:

[0071] First, assume that any comb-shaped anchor reinforcement 3 for which shear resistance calculation is required passes through the 45-degree shear plane;

[0072] Then it is concluded that the shortest anchorage length l0 on both sides of the shear surface is l0﹤25d, where d is 5 times the diameter of the corresponding comb-tooth anchor steel bar 3;

[0073] Then, the shear resistance V that the selected comb-shaped anchor steel bar (3) can provide is ds Calculate according to the following formula:

[0074] V ds =(l0 / 25d)*V s ;

[0075]

[0076] Where Av is the total area of ​​U-shaped restraining steel bars 5 in the calculation direction, in cm 2 ;

[0077] f yh is the design value of stirrup tensile strength, in MPa;

[0078] h0 is the distance from the compression edge of the core concrete to the center of gravity of the steel bars on the tension side, in cm;

[0079] s is the spacing of the restraining steel bars 5, in cm.

[0080] In practical applications, since the U-shaped restraining steel bar 5 is used to realize the comb-shaped anchoring steel bar (3), the U-shaped restraining steel bar 5 can also be used for calculation. Fig.11 The 45-degree shear surface shown in the figure can be used to judge that for steel bars whose extension length of the U-shaped restraint steel bars 5 on the shear surface is greater than 25 times the diameter of the U-shaped restraint steel bars 5, the total shear capacity V can be calculated. s For the steel bars with anchorage length on one side of the shear plane less than 25 times the diameter of the U-shaped restraining steel bar 5, the shear capacity shall be reduced linearly.

[0081] Assume that a U-shaped restraint steel bar 5 passes through a 45-degree shear plane, and the shortest anchorage length on both sides of the shear plane is l0, and l0 < 25d, where d is the diameter of the U-shaped restraint steel bar 5. The shear resistance that this U-shaped restraint steel bar can provide is V ds =(l0 / 25d)*V s ,in Where Av is the total area of ​​U-shaped restraint steel bars 5 in the calculation direction (cm 2 ), f yh is the design value of stirrup tensile strength (Mpa), h0 is the distance from the compression edge of the core concrete to the center of gravity of the tensile side reinforcement (cm), and s is the spacing of the restraining reinforcement 5 (cm).

[0082] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A comb-tooth column stirrup structure, comprising a plurality of outer ring closed stirrups (2) uniformly distributed along the length direction of the column and having a ring-shaped shape matching the cross-sectional shape of the column, and a plurality of longitudinal force-bearing steel bars (1) parallel to the length direction of the column, surrounding and closely attached to the inner side of each outer ring closed stirrup (2); characterized in that: Each of the outer ring closed stirrups (2) is provided with a plurality of comb-tooth-shaped anchoring steel bars (3) extending inwardly; A longitudinal force-bearing steel bar (1) is provided on one side of each of the comb-tooth anchoring steel bars (3), and the extending direction is within the plane formed by the corresponding outer ring closed stirrups (2), and the end extending into the inner side of the corresponding outer ring closed stirrups (2) has a bent structure with an angle less than 90 degrees as an anchoring end; The plane formed by each of the bent structures is perpendicular to the plane formed by the corresponding outer ring closed stirrups (2), and the opening direction is toward the outside of the corresponding outer ring closed stirrups (2); Each of the outer ring closed stirrups (2) is connected to all the comb-tooth anchor steel bars (3) by connecting a plurality of U-shaped restraining steel bars (5) with the comb-tooth anchor steel bars (3); Each of the U-shaped restraining steel bars (5) comprises two comb-tooth anchoring steel bars (3) and a connecting portion arranged between the two comb-tooth anchoring steel bars (3) and connected to the corresponding outer ring closed stirrup (2); Two or more U-shaped restraining steel bars (5) with different connecting parts are welded together to form a first assembly with an even number of comb-tooth anchoring steel bars (3); Each of the first-type assemblies is fixed by a weld formed by welding between the corresponding connecting portion with the longest length and the corresponding outer ring closed stirrup (2); Alternatively, when two or more U-shaped restraining steel bars (5) with the same length of the connecting parts are fixed to the skeleton steel bar (4) by welding, a second assembly with an even number of comb-tooth-shaped anchoring steel bars (3) is formed; Each of the second-type assemblies is fixed by a weld formed by welding between the corresponding skeleton steel bar (4) and the corresponding U-shaped restraining steel bar (5); The shape of each skeleton steel bar (4) matches the connecting portion of the corresponding outer ring closed stirrup (2).

2. The comb-tooth column stirrup structure according to claim 1 is characterized in that: Each of the outer ring closed stirrups (2) is a closed annular structure, and its shape is circular, oblong, elliptical or convex polygonal, matching the cross section of the corresponding column.

3. The comb-tooth column stirrup structure according to claim 1, characterized in that: Each of the skeleton steel bars (4) comprises a bent section in the corresponding outer ring closed stirrup (2), which is overlapped with a portion of the corresponding outer ring closed stirrup (2) having a matching shape.

4. The comb-tooth column stirrup structure according to claim 1, characterized in that: The maximum distance between each of the longitudinal force-bearing steel bars (1) and the closest comb-tooth anchoring steel bar (3) on each of the outer ring closed stirrups (2) is less than 15 times the diameter of the corresponding comb-tooth anchoring steel bar (3); The length of each of the comb-tooth anchoring steel bars (3) extending into the corresponding outer ring closed stirrups (2) is 25 times the diameter of the corresponding comb-tooth anchoring steel bar (3).

5. The method for calculating the shear resistance provided by the comb teeth of the comb-tooth column stirrup structure according to claim 1 is characterized in that: The steps include: First, it is assumed that any of the comb-shaped anchor steel bars (3) for which shear resistance calculation is required passes through a 45-degree shear plane; Then, it is obtained that the shortest anchorage length l0 on both sides of the shear surface is l0 < 25d, where d is 5 times the diameter of the corresponding comb-tooth anchor steel bar (3); Then, the shear resistance V that the selected comb-shaped anchor steel bar (3) can provide is ds Calculate according to the following formula: V ds =(l0 / 25d)*V s ; Where Av is the total area of ​​the U-shaped restraining steel bars (5) in the calculation direction, in cm 2 ; f yh is the design value of stirrup tensile strength, in MPa; h0 is the distance from the compression edge of the core concrete to the center of gravity of the steel bars on the tension side, in cm; s is the spacing of the restraining steel bars 5, in cm.

Images