A reinforced concrete embedded column base joint with special-shaped section and reinforced steel framework

Abstract

This invention provides a reinforced, irregularly shaped cross-section steel-concrete composite column base joint, comprising an irregularly shaped cross-section steel-concrete composite column. The lower perimeter of the irregularly shaped cross-section steel-concrete composite column is surrounded by a reinforcing steel reinforcement cage, which includes upward and downward reinforcing bars embedded in the foundation. By adding a reinforcing steel reinforcement cage around the irregularly shaped cross-section steel-concrete composite column, and embedding the upward and downward reinforcing bars of the cage into the foundation, this invention effectively enhances the connection between the column base joint and the surrounding foundation concrete, thereby improving the punching shear resistance and seismic resistance of the column base joint, and ultimately reducing the embedment depth of the embedded column base.

Description

Technical Field

[0001] This invention relates to the field of engineering structure technology, and in particular to a reinforced steel tube concrete embedded column base joint with a steel reinforcement cage. Background Technology

[0002] Irregularly shaped cross-section steel tube concrete structure columns enable the steel tube and its internal core concrete to work together to provide greater load-bearing capacity and stronger stability. Furthermore, the irregular cross-section design can effectively solve the problem of protruding columns, making the wall surface flat and beautiful, saving more building space, and thus improving the overall aesthetics and comfort.

[0003] As a crucial node connecting the superstructure and the foundation, column bases are of paramount importance in seismic design. However, according to formulas in existing codes, the minimum embedment depth of embedded column bases is often required to be 2 to 3 times the cross-sectional width (radius). This design depth is often too large for irregularly shaped column bases, leading to excessively large foundation dimensions, increased excavation depth, more complex column base construction, longer construction period, and ultimately higher construction costs. Summary of the Invention

[0004] To address the aforementioned issues, this invention aims to propose a reinforced steel tube concrete embedded column base joint with an irregular cross-section. By adding an external reinforcing steel skeleton, the connection between the column base joint and the surrounding foundation concrete is effectively enhanced, thereby improving the punching shear resistance and seismic resistance of the column base joint, and thus achieving the goal of reducing the embedment depth of the embedded column base.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A reinforced steel tube concrete embedded column base joint with a steel reinforcement cage includes a steel tube concrete column with a steel reinforcement cage around its lower perimeter. The reinforced steel reinforcement cage includes upward reinforcing bars and downward reinforcing bars embedded in the foundation.

[0007] Furthermore, the irregular cross-section steel tube concrete column includes an irregular cross-section multi-cavity steel tube, and concrete is poured into the inner cavity of the irregular cross-section multi-cavity steel tube.

[0008] Furthermore, a column base plate is welded to the bottom of the irregular cross-section multi-cavity steel pipe. The column base plate has holes at positions corresponding to the inner cavity of the steel pipe. Several holes are opened at predetermined positions on the outer ring of the column base plate, and anchor bolts are installed through the holes and anchor nuts.

[0009] Furthermore, several sets of PBL connecting plates are provided between the column base plate and the outer wall side of the multi-cavity steel pipe with irregular cross-section. Each set of PBL connecting plates has holes on its side, through which upward reinforcing bars and downward reinforcing bars are installed in a staggered manner.

[0010] Furthermore, the upward and downward reinforcing bars intersect vertically to form an X-shaped intersection, and after extending a certain distance, they become horizontal and connect with the longitudinal bars in the foundation.

[0011] Furthermore, both the upward reinforcing bars and the downward reinforcing bars are prestressed tendons.

[0012] Furthermore, regarding punching shear resistance, mechanical property analysis shows that when the column is subjected to axial pressure, the upward reinforcing bars are under tension, resisting the downward punching shear at the column base; the downward reinforcing bars are under shear and work together with the foundation concrete to resist punching shear; the actual bearing capacity formulas for the downward and upward reinforcing bars are as follows:

[0013] V≤V cs +V p +0.8f yv A sb sinα s +0.8f py A pb sinα p

[0014] in:

[0015] V—Actual value of shear force at the location of bent-up reinforcement;

[0016] V cs —Design values ​​of shear capacity of concrete and stirrups on the inclined section of the member;

[0017] V p —The design value of the shear capacity of the member increased by the prestressing force;

[0018] V cs and V p It can be calculated according to the formula in the "Code for Design of Concrete Structures GB50010-2010";

[0019] A sb A pb —These are the cross-sectional areas of bent-up ordinary steel bars and bent-up prestressed tendons in the same plane, respectively;

[0020] α s α p — These are the angles between the tangents of the bent-up ordinary steel bars and bent-up prestressed steel bars on the inclined section and the longitudinal axis of the member, respectively;

[0021] The additional punching shear capacity provided by the node, when using ordinary steel reinforcement, is increased by 0.8fyv A sb sinα s Calculations are performed, and when prestressed steel bars are used, the value is 0.8f. py A pb sinα p Perform calculations;

[0022] Regarding the seismic performance of the column base joint, according to mechanical analysis, when the column tilts, tensile forces will be generated in the upward reinforcing bars in at least one direction and the downward reinforcing bars opposite to them, which will be transferred to the concrete-filled steel tube column to generate bending moments to resist the bending moments generated by the earthquake.

[0023] Bending moment generated by tension:

[0024] M s =f u A u l u sinα u +f d A d l d sinα d ;

[0025] The resultant horizontal force generated by the tension:

[0026] N s =f u Δ u sinα u +f d A d sinα d ;

[0027] in:

[0028] A u A d —These are the cross-sectional areas of the upward and downward reinforcing bars in the same plane, respectively;

[0029] α u α d —These are the angles between the tangents of the upward and downward reinforcing bars and the longitudinal axis of the component, respectively;

[0030] l u l d —These are the vertical distances from the midpoint of the embedded part to the point of action of the combined force of the upward and downward reinforcing bars;

[0031] According to the system of equations:

[0032]

[0033] The formula for calculating the concrete bearing stress of embedded column bases can be derived:

[0034]

[0035] in:

[0036] V—Column base shear force;

[0037] h0—the distance from the inflection point of the column to the top surface of the foundation;

[0038] d—depth of column base;

[0039] b f —Column base cross-section width;

[0040] x — the distance from the column base plate to the neutral axis;

[0041] Therefore, the formula for calculating the embedment depth of a common embedded column base is as follows:

[0042]

[0043] Applying the same principle to the embedded column base joint of irregularly shaped steel tube concrete reinforced with a steel cage, the effect is shown by the formula for embedment depth:

[0044]

[0045] This shows that it can effectively reduce the lower limit of burial depth.

[0046] Furthermore, the cross-section of the irregularly shaped multi-cavity steel pipe is cross-shaped, and the column base plate is also cross-shaped.

[0047] Furthermore, the foundation is a base plate or a pile cap.

[0048] Beneficial effects: This invention effectively enhances the connection between the column base joint and the surrounding foundation concrete by adding an external reinforcing steel skeleton, thereby improving the punching shear resistance and seismic resistance of the column base joint, and thus achieving the purpose of reducing the embedment depth of the embedded column base. Attached Figure Description

[0049] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0050] In the attached diagram:

[0051] Figure 1 This is a schematic elevation view of the irregular cross-section steel tube concrete embedded column foot node reinforced with steel reinforcement cage according to an embodiment of the present invention.

[0052] Figure 2 for Figure 1 Top view;

[0053] Figure 3 This is a three-dimensional structural schematic diagram of the irregular cross-section steel tube concrete embedded column foot node reinforced with steel reinforcement cage according to an embodiment of the present invention. Detailed Implementation

[0054] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0055] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] Example 1

[0057] See Figure 1-3 A reinforced steel tube concrete embedded column base joint with a steel reinforcement cage includes a steel tube concrete column 1 with a steel reinforcement cage 5 around its lower perimeter. The steel reinforcement cage 5 includes an upward reinforcing bar 51 and a downward reinforcing bar 52 embedded in the foundation 8.

[0058] This embodiment uses an external reinforcing steel reinforcement cage around the irregular cross-section steel tube concrete column. The upward and downward reinforcing bars of the reinforcing steel reinforcement cage are embedded in the foundation, which can effectively enhance the connection between the column foot joint and the surrounding foundation concrete, thereby improving the punching shear resistance and seismic resistance of the column foot joint, and thus achieving the purpose of reducing the embedment depth of the embedded column foot.

[0059] In a specific example, the irregular cross-section steel tube concrete column 1 includes an irregular cross-section multi-cavity steel tube 11, and concrete 12 is poured into the inner cavity of the steel tube 11.

[0060] It should be noted that the irregular cross-section multi-cavity steel pipe in this embodiment is formed by connecting multiple steel pipes, and concrete is poured inside the cavity of the steel pipe to form the core concrete.

[0061] In a specific example, a column base plate 6 is welded to the bottom of the irregular cross-section multi-cavity steel pipe 11. The column base plate 6 has holes at positions corresponding to the inner cavity of the steel pipe 11. Several holes are opened at predetermined positions on the outer ring of the column base plate 6. Anchor bolts 4 are installed by matching the anchor nuts 3 through the opening positions.

[0062] The central opening in the base plate of this embodiment allows the concrete inside the steel pipe to leak in and form an integral part of the foundation during pouring, preventing the foundation and the embedded column base of the irregular cross-section steel pipe from becoming independent of each other due to the partition of the base plate.

[0063] In practice, the size of the column base plate is larger than that of the irregular cross-section steel pipe. Anchor bolts are installed on the column base plate on the outside of the steel pipe concrete column and fixed by fixing nuts. The anchor bolts connect the base plate and the foundation, and the barbs of the anchor bolts face outward to further improve the connection strength of the structure.

[0064] In a specific example, several sets of PBL connecting plates 2 are provided between the column base plate 6 and the outer wall side of the multi-cavity steel pipe 11 with irregular cross-section. Each set of PBL connecting plates 2 has holes on its side, and the upward reinforcing bars 51 and the downward reinforcing bars 52 are installed through the holes in a staggered manner.

[0065] The PBL connecting plate in this embodiment has good stress performance and is easy and simple to construct, and can effectively fix and install the upward and downward reinforcing bars.

[0066] In a specific example, the upper reinforcing bar 51 and the lower reinforcing bar 52 intersect vertically to form an X-shaped intersection, and after extending a certain distance, they become horizontal and connect with the longitudinal reinforcing bar 7 in the foundation 8.

[0067] Understandably, regarding punching shear resistance, mechanical performance analysis shows that when the column is subjected to axial pressure, the upward reinforcing steel cage is under tension, resisting the downward punching shear at the column base; the downward reinforcing steel is under shear and together with the foundation concrete resists punching shear. Regarding the seismic performance of the column base joint, mechanical analysis shows that when the column tilts, at least one direction of the upward reinforcing steel and the opposite downward reinforcing steel will generate tensile forces acting on the PBL slab, which will then be transferred to the concrete-filled steel tube column to generate bending moments that resist the bending moments generated by earthquakes.

[0068] In a specific example, both the upward reinforcing bar 51 and the downward reinforcing bar 52 are prestressed tendons.

[0069] It should be noted that when prestressed tendons are used as the upper and lower reinforcing bars of the reinforcing steel skeleton, the column base joint also has a certain energy dissipation, vibration reduction and self-resetting function.

[0070] In a specific example, based on mechanical performance analysis, regarding the punching shear resistance, when the column is subjected to axial pressure, the upward reinforcing bar 51 is under tension, resisting the downward punching shear at the column base; the downward reinforcing bar 52 is under shear and, together with the foundation concrete, resists the punching shear; the actual bearing capacity formulas for the downward reinforcing bar 51 and the upward reinforcing bar 52 are as follows:

[0071] V≤V cs +V p +0.8f yv A sb sinα s +0.8f py A pb sinα p

[0072] in:

[0073] V—Actual value of shear force at the location of bent-up reinforcement;

[0074] V cs —Design values ​​of shear capacity of concrete and stirrups on the inclined section of the member;

[0075] V p —The design value of the shear capacity of the member increased by the prestressing force;

[0076] V cs and V p It can be calculated according to the formula in the "Code for Design of Concrete Structures GB50010-2010";

[0077] A sb A pb —These are the cross-sectional areas of bent-up ordinary steel bars and bent-up prestressed tendons in the same plane, respectively;

[0078] α s α p — These are the angles between the tangents of the bent-up ordinary steel bars and bent-up prestressed steel bars on the inclined section and the longitudinal axis of the member, respectively;

[0079] The additional punching shear capacity provided by the node, when using ordinary steel reinforcement, is increased by 0.8f yv A sb sinα s Calculations are performed, and when prestressed steel bars are used, the value is 0.8f. py A pb sinα p Perform calculations;

[0080] Regarding the seismic performance of the column base joint, according to mechanical analysis, when the column tilts, tensile forces will be generated in the upward reinforcing bars in at least one direction and the downward reinforcing bars opposite to them, which will be transferred to the concrete-filled steel tube column to generate bending moments to resist the bending moments generated by the earthquake.

[0081] Bending moment generated by tension:

[0082] M s =f u A u l u sinα u +f d A d l d Sinα d ;

[0083] The resultant horizontal force generated by the tension:

[0084] Ns =f u Δ u sinα u +f d A d sinα d ;

[0085] in:

[0086] A u A d —These are the cross-sectional areas of the upward and downward reinforcing bars in the same plane, respectively;

[0087] α u α d —These are the angles between the tangents of the upward and downward reinforcing bars and the longitudinal axis of the component, respectively;

[0088] l u l d —These are the vertical distances from the midpoint of the embedded part to the point of action of the combined force of the upward and downward reinforcing bars;

[0089] According to the system of equations:

[0090]

[0091] The formula for calculating the concrete bearing stress of embedded column bases can be derived:

[0092]

[0093] in:

[0094] V—Column base shear force;

[0095] h0—the distance from the inflection point of the column to the top surface of the foundation;

[0096] d—depth of column base;

[0097] b f —Column base cross-section width;

[0098] X—the distance from the column base plate to the neutral axis;

[0099] Therefore, the formula for calculating the embedment depth of a common embedded column base is as follows:

[0100]

[0101] Applying the same principle to the embedded column base joint of irregularly shaped steel tube concrete reinforced with a steel cage, the effect is shown by the formula for embedment depth:

[0102]

[0103] This shows that it can effectively reduce the lower limit of burial depth.

[0104] The staggered design of the upward and downward reinforcing bars in this embodiment can reduce the embedment depth, and ensure punching shear resistance and seismic resistance even with a low embedment depth.

[0105] In a specific example, the cross-section of the irregularly shaped multi-cavity steel pipe 11 is cross-shaped, and the column base plate 6 is also cross-shaped.

[0106] It should be noted that the cross-shaped section of the steel-concrete composite column and the cross-shaped column base plate shown in the figure are only schematic diagrams. This embodiment can also be applied to L-shaped, T-shaped cross-section steel-concrete composite columns or columns and column base plates of other shapes.

[0107] In practical implementation, the geometric dimensions of the reinforcing cage, including the upward and downward reinforcing bars, can be determined based on stress requirements and structural specifications. The height of the reinforcing cage, i.e., the height of the PBL connection plate, can be determined based on stress calculations and structural requirements. Simultaneously, the number and spacing of holes in the PBL connection plate can also be determined based on stress calculations and structural requirements. In actual engineering projects, the anchor bolts are inserted downwards into the foundation to meet the anchorage depth requirements.

[0108] In a specific instance, the foundation 8 is a foundation plate or a pile cap.

[0109] In summary, this embodiment involves reserving anchor bolts around the outer ring of the column base plate during construction, following conventional practices. After the foundation pre-filled concrete reaches its strength, the prefabricated multi-cavity steel pipe with irregular cross-section of the steel pipe column is positioned in the factory, the anchor bolts are adjusted and installed, the fixing nuts are installed, and the rising and falling reinforcing bars are connected to the longitudinal reinforcement of the foundation. Subsequently, concrete can be poured into the inside of the steel pipe and the rest of the foundation to form a steel pipe concrete column and foundation.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A reinforced concrete-filled steel tube column base joint with an irregular cross-section, characterized in that, The column includes a steel tube concrete column (1) with irregular cross-section. The lower part of the steel tube concrete column (1) is provided with a reinforcing steel skeleton (5). The reinforcing steel skeleton (5) includes an upward reinforcing steel (51) and a downward reinforcing steel (52) embedded in the foundation (8). The steel tube concrete column (1) with irregular cross-section includes a multi-cavity steel tube (11) with irregular cross-section. The bottom of the multi-cavity steel tube (11) with irregular cross-section is welded with a column base plate (6). Several sets of PBL connecting plates (2) are provided between the column base plate (6) and the outer wall of the steel tube of the multi-cavity steel tube (11). Each set of PBL connecting plates (2) has holes on its side. The upward reinforcing steel (51) and the downward reinforcing steel (52) are installed through the holes in a staggered manner. The upward reinforcing steel (51) and the downward reinforcing steel (52) intersect vertically to form an X-shaped intersection. After extending a certain distance, they become horizontal and connect with the longitudinal reinforcement (7) in the foundation (8).

2. The reinforced steel-concrete composite column base joint with irregular cross-section steel tube as described in claim 1, characterized in that, The inner cavity of the irregular cross-section multi-cavity steel pipe (11) is filled with concrete (12).

3. The reinforced steel-concrete composite column base joint with irregular cross-section steel tube as described in claim 2, characterized in that, The column base plate (6) has holes at positions corresponding to the inner cavity of the multi-cavity steel pipe (11) with irregular cross-section. Several holes are set at positions on the outer ring of the column base plate (6), and anchor bolts (4) are installed by matching the anchor nuts (3) with the hole positions.

4. The reinforced concrete-filled steel tube column base joint with irregular cross-section as described in claim 1, characterized in that, Both the upward reinforcing bar (51) and the downward reinforcing bar (52) are prestressed tendons.

5. The reinforced steel-concrete composite column base joint with irregular cross-section steel tube as described in claim 4, characterized in that, According to the mechanical performance analysis, when the column is subjected to axial pressure, the upward reinforcing bar (51) is under tension, resisting the downward punching shear at the column base; the downward reinforcing bar (52) is under shear and resists the punching shear together with the foundation concrete. The actual bearing capacity formulas of the downward reinforcing bar (52) and the upward reinforcing bar (51) are as follows: in: — Actual shear force value at the location of the bent-up rebar; f yv f is the design value of the shear strength of bent-up ordinary steel bars; py This refers to the design value of the tensile strength of the bent-up prestressing tendon; —Design values ​​of shear capacity of concrete and stirrups on the inclined section of the member; —The design value of the shear capacity of the member increased by the prestressing force; and It can be calculated according to the formula in the "Code for Design of Concrete Structures GB50010-2010"; , —These are the cross-sectional areas of bent-up ordinary steel bars and bent-up prestressed tendons in the same plane, respectively; , — These are the angles between the tangents of the bent-up ordinary steel bars and bent-up prestressed steel bars on the inclined section and the longitudinal axis of the member, respectively; The additional punching shear capacity provided by the node, when using ordinary steel reinforcement, is... Calculations are performed when prestressed steel bars are used. Perform calculations; Regarding the seismic performance of the column base joint, according to mechanical analysis, when the column tilts, tensile forces will be generated in the upward reinforcing bars in at least one direction and the downward reinforcing bars opposite to them, which will be transferred to the concrete-filled steel tube column to generate bending moments to resist the bending moments generated by the earthquake. Bending moment generated by tension: ； The resultant horizontal force generated by the tension: ； in: , —These are the cross-sectional areas of the upward and downward reinforcing bars in the same plane, respectively; , —These are the angles between the tangents of the upward and downward reinforcing bars and the longitudinal axis of the component, respectively; , —These are the vertical distances from the midpoint of the embedded part to the point of action of the combined force of the upward and downward reinforcing bars; f u This is the design value for the tensile strength of the upward-moving reinforcing bars; f d This is the design value for the tensile strength of the submerged reinforcing steel. According to the system of equations: The formula for calculating the concrete bearing stress of embedded column bases can be derived: in: —Column base shear force; —The distance from the inflection point of the column to the top surface of the foundation; —Column base depth; —Column base cross-section width; x — the distance from the column base plate to the neutral axis; Therefore, the formula for calculating the embedment depth of a common embedded column base is as follows: Applying the same principle to the embedded column base joint of irregularly shaped steel tube concrete reinforced with a steel cage, the effect is shown by the formula for embedment depth: This shows that it can effectively reduce the lower limit of burial depth.

6. The reinforced steel-concrete composite column base joint with irregular cross-section as described in claim 1, characterized in that, The cross section of the irregular cross section multi-cavity steel pipe (11) is cross-shaped, and the column base plate (6) is cross-shaped.

7. The reinforced steel-concrete composite column base joint with irregular cross-section as described in claim 1, characterized in that, The foundation (8) is a foundation plate or a pile cap.

Images