Concrete-filled steel tubular column frame joint for simultaneously connecting steel beam and reinforced concrete beam and design method

Abstract

The invention discloses a concrete filled steel tubular column frame joint for simultaneously connecting a steel beam and a reinforced concrete beam and a design method. The joint comprises a steel pipe concrete column, a reinforced concrete beam, a steel beam and an annular steel corbel welded to the outer side of a column body. The annular steel corbel is composed of an upper reinforcing ring, a lower reinforcing ring and a rib plate, and a ring beam of an annular reinforced concrete structure is formed above the upper reinforcing ring and below the lower reinforcing ring within a certain range. Longitudinal bars on the lower portion of the reinforced concrete beam are fixed below the lower reinforcing ring through anchor plates, the steel beam is connected with the cantilever H-shaped steel beam through high-strength bolts, and ring beam steel bars penetrate through holes in a cantilever beam web. Through the synergistic effect of the annular steel corbel and the reinforced concrete ring beam, the joint shear bearing capacity is remarkably improved, the bending moment transmission path is optimized, and the problems that a traditional joint is weak in shear resistance, not direct in force transmission, large in field welding amount and the like are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural engineering, and in particular relates to a steel tube concrete column frame node for simultaneously connecting a steel beam and a reinforced concrete beam and a design method thereof. Background Art

[0002] Concrete-filled steel tubular (CFST) columns are widely used in current high-rise buildings because they effectively avoid the "fat column" problem of reinforced concrete columns and the wind-induced vibration defects of steel columns. Existing high-rise buildings generally adopt a hybrid structural system of CFST columns and steel beams or reinforced concrete beams (hereinafter referred to as RC beams). However, the connection nodes between CFST columns and steel beams or RC beams still have significant shortcomings: although traditional ring beam connection nodes can transmit bending moments, the shear bearing capacity of the core area of ​​the node is insufficient. For example, the structure shown in patent CN105442712B has the problem of weak shear resistance in the lower part of the ring beam; although the annular corbel node (CN206591644U) improves shear resistance, it requires a large amount of on-site welding and high steel consumption; although the open-hole node (CN213805826U) reduces the size, the opening in the pipe wall leads to a decrease in the bearing capacity of the core area; although the through-hole node (CN221143071U) reduces welding, it relies on friction and longitudinal reinforcement to transmit shear force and bending moment respectively, and its shear and bending performance are both unsatisfactory.

[0003] Especially in large cantilever conditions, anchoring the upper longitudinal reinforcement of RC beams is difficult, while steel beam connection nodes cannot fully exploit the load-bearing advantages of RC beams. Existing technologies have failed to address the following contradictions: 1) the difficulty in simultaneously optimizing both shear and bending resistance at the joints; 2) the coordination between factory prefabrication and on-site construction; and 3) the compatibility of reinforced concrete and steel connections.

[0004] Therefore, it is urgent to develop a new type of node that can simultaneously improve the shear and bending performance, reduce on-site welding, and connect steel beams and RC beams to meet the seismic resistance and construction requirements of high-rise buildings. Summary of the Invention

[0005] The present invention aims to provide a steel tube concrete column frame node and design method that simultaneously connects steel beams and reinforced concrete beams. Through the composite structure of annular steel corbels and reinforced concrete ring beams, the shear bearing capacity of the node is significantly improved and the bending moment transmission path is optimized, thereby solving the problems of weak shear resistance, indirect force transmission, and large amount of on-site welding in traditional nodes, realizing the seismic design concept of strong nodes and weak components, and taking into account the convenience of factory prefabrication and on-site construction.

[0006] In order to solve the above technical problems, the technical solution proposed in this application is: The present invention provides a steel tube concrete column frame node for simultaneously connecting a steel beam and a reinforced concrete beam, comprising: Concrete-filled steel tube columns, reinforced concrete beams, and steel beams; An annular steel corbel welded to the outside of the steel tube concrete column, the annular steel corbel comprising an upper reinforcement ring, a lower reinforcement ring, and a rib connecting the upper reinforcement ring and the lower reinforcement ring; a reinforced concrete ring beam arranged around the concrete-filled steel tube column, wherein the reinforced concrete ring beam is an annular reinforced concrete structure centered on the concrete-filled steel tube column and supported by an upper reinforcement ring and a lower reinforcement ring; in: The lower longitudinal reinforcement of the reinforced concrete beam is anchored to an anchor plate fixed below the lower reinforcement ring, and the upper longitudinal reinforcement of the reinforced concrete beam extends into the opposite side of the reinforced concrete ring beam and bends downward; The steel beam is connected to a cantilever H-shaped steel beam by high-strength bolts. The cantilever H-shaped steel beam is welded to the steel tube concrete column and the web is opened. An inner column partition is provided inside the steel tube concrete column at the same height as the upper flange of the cantilever H-shaped steel beam. The steel bars of the reinforced concrete ring beam pass through the holes of the web of the cantilever H-shaped steel beam.

[0007] Furthermore, the thickness of the upper reinforcement ring is 20 mm, the thickness of the lower reinforcement ring is 20 mm, and the thickness of the rib plate is ≥ 20 mm; The lower reinforcement ring is provided with exhaust holes with a diameter of ≥50 mm at intervals of 45° along the circumferential direction.

[0008] Furthermore, when connected to a reinforced concrete beam, the reinforced concrete ring beam comprises closed stirrups and open stirrups; The closed stirrups are closed with 90° hooks, and the straight section length after bending is not less than 12d; The open stirrups are made of U-shaped stirrups bent and welded, with a welding length of ≥12d; or overlapped, with an overlap rate of 50% and an overlap length of 56d.

[0009] Furthermore, when connected to the steel beam, the reinforced concrete ring beam comprises closed stirrups and open stirrups; The closed stirrups are connected by overlapping, with an overlapping rate of 100% and an overlapping length of 64d; The open stirrups are made of U-shaped stirrups bent and welded, with a welding length of ≥12d; or overlapped, with an overlap rate of 100% and an overlap length of 64d.

[0010] Furthermore, the height of the cantilever H-shaped steel beam is equal to the height of the connecting steel beam, and the length of the cantilever H-shaped steel beam is greater than or equal to the height of the connecting steel beam; The flange thickness of the cantilever H-shaped steel beam is equal to the flange thickness of the connecting steel beam, and the web thickness of the cantilever H-shaped steel beam is the web thickness of the connecting steel beam + 2 mm.

[0011] Furthermore, the reinforced concrete ring beam comprises: The upper reinforcement of the ring beam is arranged in the area above the upper reinforcement ring; The lower reinforcement of the ring beam is arranged in the area below the lower reinforcement ring; Ring beam waist reinforcement and structural reinforcement are arranged from the outside of the circular steel corbel to the edge of the ring beam; Ring beam stirrups include closed stirrups and open stirrups.

[0012] Furthermore, a 90° hook is provided at the closed portion of the closed stirrup, and the straight section length of the hook is ≥12d.

[0013] On the other hand, the present application also seeks protection for a design method of a framework node as described in any of the foregoing items, comprising: Calculation of shear capacity of circular steel corbel:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] Where: V u1 - shear capacity determined by the local compressive strength of the concrete on the annular corbel support surface; V u2 — shear bearing capacity determined by the shear strength of the ribs; V u3 — Shear bearing capacity determined by the welding strength between the rib and the tube wall; V u4 - shear capacity determined by the direct shear or punching shear strength of the concrete above the annular corbel; V u5 ——The shear bearing capacity determined by the upper and lower ring plates of the annular corbel; β 2——Increase coefficient of local compressive strength of concrete, β 2 can be taken as 1; D ——outer diameter of the steel pipe; b —Width of ring plate; l —height of the straight shear surface; t —Thickness of the ring plate; n — number of ribs; h w - height of ribs; t w —thickness of ribs; f v ——Design value of shear strength of steel; f a — design value of tensile or compressive strength of steel; ∑ l w —Calculated total length of fillet welds connecting ribs and steel pipe walls; h e ——Effective height of fillet weld; f f w — Design value of shear strength of fillet weld; f c ——design value of concrete compressive strength; f t ——Design value of concrete tensile strength.

[0020] Furthermore, it also includes the calculation of the tension ring reinforcement area of ​​the ring beam: When the diameters of the annular reinforcements in the upper portion of the ring beam are the same and the horizontal spacing is equal, the area of ​​the tensioned ring reinforcement and the area of ​​a single stirrup in the ring beam shall comply with the following requirements: 1) When the beneficial effect of the floor slab is not considered, the calculation should be carried out according to the following formula:

[0021]

[0022] 2) When considering the beneficial effect of the floor slab, the calculation should be carried out according to the following formula:

[0023]

[0024]

[0025]

[0026] ; Among them, under the action of negative bending moment, β 1 takes 0.5, β 2 takes 0.65, β3 is taken as 0.6; taken under the action of positive bending moment β 1= β 2= β 3=1.0; i 1 – the central angle corresponding to the projection length of the frame beam on the outer edge of the ring beam; i 2 – the central angle corresponding to the projected length of the upper surface crack on the outer edge of the ring beam when the ring beam fails; α 0——the central angle corresponding to the projected length of the side crack on the outer edge of the ring beam when the ring beam is damaged; R ——Ring beam radius, i.e. the radial distance from the edge of the ring beam to the center of the steel pipe; r ——radius of steel pipe; 3) Calculate the area of ​​a single stirrup:

[0027] Where: l ——Shear-ring ratio, which is the ratio of the nominal tension of the ring beam stirrups to the nominal tension of the tension ring bars of the ring beam. l = F v / F h , which can be 0.35~0.7. Take the higher value when the effect of the floor is not considered, and take the lower value when the effect of the floor is considered; F h ——nominal tension of the tension ring reinforcement (N), F h = 0.7 f yh A sh ; f yh ——Design value of tensile strength of hoop reinforcement (MPa); A sh ——Cross-sectional area of ​​circumferential reinforcement (mm 2 ); F v ——nominal tension of ring beam stirrups (N), F h = α v A sv f yv / c H ; f yv ——Design value of stirrup tensile strength (MPa); c H ——the angle between stirrups (radians), c H = S / ( r + b h / 2); S ——Stirrup spacing at the center line of the ring beam (mm); A sv ——Area of ​​single stirrup of ring beam (mm 2 ); α v ——Calculation coefficient of closed stirrups; M k ——Bending moment of the frame beam end calculated from the actual reinforcement (N•mm); α dp ——Test correction coefficient, take α dp =1. 3; l r ——The moment arm from the point of action of the resultant force of the tension ring reinforcement of the ring beam to the resultant force point of the compression zone is taken as min{0.87 h r0 , h r -50}; h r ——height of the ring beam section (mm); h r0 ——Effective height of ring beam section (mm); b k ——Width of the frame beam connected to the ring beam (mm).

[0028] Furthermore, it also includes the calculation of the tension ring reinforcement area of ​​the ring beam: When the strength grade of the ring beam's annular reinforcement is the same as that of the frame beam, the diameter of the annular reinforcement is the same, and the horizontal spacing is equal, the area of ​​the ring beam's tension reinforcement and the area of ​​a single stirrup can be calculated using the following formula: 1) When the floor effect is not considered:

[0029]

[0030] 2) When considering the effect of floor slab:

[0031]

[0032] Where: A sk ——Area of ​​tensile reinforcement at the end of frame beam (mm 2 ); f y ——Design value of tensile strength of annular reinforcement of ring beam (MPa).

[0033] Compared with the prior art, the present invention has achieved the following beneficial technical effects: The present invention significantly improves the shear bearing capacity and bending moment transfer efficiency of the node through the coordinated construction of the annular steel corbel and the reinforced concrete ring beam, thus solving the problems of weak shear resistance and indirect force transmission of traditional nodes; it uses factory-prefabricated cantilever steel beams to reduce the amount of on-site welding and improve construction convenience; at the same time, it is compatible with the connection between steel beams and reinforced concrete beams, adapts to the hybrid structure requirements of high-rise buildings, and realizes the seismic design concept of "strong nodes and weak components". BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a schematic diagram of the simultaneous connection of CFST columns with steel beams and RC beams in this application.

[0036] Figure 2 This is a structural diagram of the welding method of the open stirrups in this application.

[0037] Figure 3 This is a structural diagram of the overlap method of the open stirrups in this application.

[0038] Figure 4 This is a structural diagram of the welding method of closed stirrups in this application.

[0039] Figure 5 This is a structural diagram of the overlap method of the closed stirrups in this application.

[0040] Figure 6 Schematic diagram of the geometric meaning of parameters in the ring beam of this application.

[0041] Explanation of the accompanying numbers: 1 is the upper reinforcement of the ring beam; 2 is the lower reinforcement of the ring beam; 3 is the waist reinforcement of the ring beam; 4 is the structural reinforcement of the ring beam; 5 is the stirrups of the ring beam; 5A is the closed stirrups; 5B is the open stirrups; 6 is the lower longitudinal reinforcement of the reinforced concrete beam; 7 is the upper reinforcement ring; 7A is the lower reinforcement ring; 8 is the rib plate; 9 is the reinforced concrete beam; 10 is the steel beam; 11 is the cantilever H-shaped steel beam; 12 is the partition in the column; 13 is the steel tube concrete column; 14 is the upper longitudinal reinforcement of the reinforced concrete beam; 15 is the anchor plate; 16 is the floor slab; 17 is the high-strength bolt. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] like Figure 1 As shown, in one embodiment of the present application, a steel tube concrete column frame node for connecting a steel beam and a reinforced concrete beam at the same time comprises: Concrete-filled steel tube columns 13, reinforced concrete beams 9, and steel beams 10; An annular steel corbel welded to the outside of the steel tube concrete column, the annular steel corbel comprising an upper reinforcement ring 7, a lower reinforcement ring 7A, and a rib plate 8 connecting the upper reinforcement ring 7 and the lower reinforcement ring 7A; A reinforced concrete ring beam is provided around the concrete-filled steel tube column. The reinforced concrete ring beam is an annular reinforced concrete structure centered on the concrete-filled steel tube column and supported by the upper reinforcement ring 7 and the lower reinforcement ring 7A. in: The lower longitudinal reinforcement 6 of the reinforced concrete beam 9 is anchored to the anchor plate 15 fixed below the lower reinforcement ring 7A; The steel beam 10 is connected to a cantilever H-shaped steel beam 11 by high-strength bolts 17 , and the cantilever H-shaped steel beam 11 is welded to the steel tube concrete column and has a hole in the web; The steel bars of the reinforced concrete ring beam pass through the holes in the web of the cantilever H-shaped steel beam 11.

[0044] In the embodiment of the present application, the thickness of the upper reinforcement ring 7 is 20 mm, the thickness of the lower reinforcement ring 7A is 20 mm, and the thickness of the rib plate 8 is ≥ 20 mm; The lower reinforcement ring 7A is provided with exhaust holes with a diameter of ≥50 mm at intervals of 45° along the circumferential direction.

[0045] In the embodiment of the present application, when connected to the reinforced concrete beam 9, the reinforced concrete ring beam includes closed stirrups 5A and open stirrups 5B (see Figure 2-5 ); The closed stirrup 5A is closed with a 90° hook, and the straight section length after bending is not less than 12d; The open stirrups 5B are made of U-shaped stirrups bent and welded, with a welding length of ≥12d; or overlapped, with an overlap rate of 50% and an overlap length of 56d.

[0046] In the embodiment of the present application, when connected to the steel beam 10, the reinforced concrete ring beam includes closed stirrups 5A and open stirrups 5B; The closed stirrups 5A are connected by overlapping, with an overlapping rate of 100% and an overlapping length of 64d; The open stirrups 5B are made of U-shaped stirrups bent and welded, with a welding length of ≥12d; or overlapped, with an overlap rate of 100% and an overlap length of 64d.

[0047] In the embodiment of the present application, the height of the cantilever H-shaped steel beam 11 is equal to the height of the connecting steel beam 10 , and the length of the cantilever H-shaped steel beam 11 is ≥ the height of the connecting steel beam 10 ; The flange thickness of the cantilever H-shaped steel beam 11 is equal to the flange thickness of the connecting steel beam 10 , and the web thickness of the cantilever H-shaped steel beam 11 is the web thickness of the connecting steel beam 10 + 2 mm.

[0048] In an embodiment of the present application, the reinforced concrete ring beam comprises: The upper reinforcement 1 of the ring beam is arranged in the area above the upper reinforcement ring 7; The lower reinforcement 2 of the ring beam is arranged in the area below the lower reinforcement ring 7A; The ring beam waist reinforcement 3 and structural reinforcement 4 are arranged from the outside of the annular steel corbel to the edge of the ring beam; The ring beam stirrups 5 include closed stirrups 5A and open stirrups 5B. Those skilled in the art will appreciate that, regardless of the connection method, the ring beam stirrups 5 include closed stirrups 5A and open stirrups 5B. However, when connected to reinforced concrete beams 9 or steel beams 10, the closed stirrups 5A and open stirrups 5B may have different configurations.

[0049] The present application is further described below with reference to the embodiments: Example 1: First, a circular steel corbel structure is constructed, consisting of an upper reinforcement ring, a lower reinforcement ring, and ribs. The circular steel corbel is welded to the CFST column to effectively resist shear forces.

[0050] For connection to the RC beam, the ring beam reinforcement is arranged within the reinforced concrete ring beam height, which is 50mm higher than the RC beam height. Above the upper reinforcing ring, the upper ring beam reinforcement and open stirrups 5B are installed. These can be formed by bending open U-shaped stirrups and welding them, or by lap joints. Below the lower reinforcing ring, the lower ring beam reinforcement is installed, along with anchor plates, which anchor the lower longitudinal reinforcement of the RC beam. From the outer side of the annular steel corbel to the edge of the ring beam, the ring beam waist reinforcement, ring beam structural reinforcement, and closed stirrups 5A are installed, with the closed ends of the stirrups arranged in a staggered pattern.

[0051] Regarding the connection to the steel beam, the ring beam reinforcement is also arranged within the range of the reinforced concrete ring beam height equal to the steel beam height plus 50mm. The upper ring beam reinforcement and open stirrups 5B are set above the upper reinforcing ring, which can be bent and welded using open U-shaped stirrups or connected by lap joints. The lower ring beam reinforcement is set below the lower reinforcing ring. Ring beam waist reinforcement, ring beam structural reinforcement, and closed stirrups 5A are set from the outside of the annular steel corbel to the edge of the ring beam, and lap joints are used. In addition, a cantilever H-shaped steel beam is set within the height range of the ring beam and welded to the CFST column. The height of the cantilever H-shaped steel beam is consistent with that of the connecting steel beam, and its length is not less than the height of the connecting steel beam.

[0052] Regarding the specific structural parameters of the circular steel corbel, the upper and lower reinforcement rings and ribs are all made of Q355C steel. The upper and lower reinforcement rings are connected to the CFST column using groove welds, while the ribs can be connected to the CFST column using fillet welds. The upper and lower reinforcement rings are 20mm thick, with the ribs no less than 20mm thick. Furthermore, the lower reinforcement ring has vent holes with a diameter of no less than 50mm at 45° intervals along the circumference.

[0053] Regarding the details of the ring beam stirrup arrangement when connecting to the RC beam: If open stirrup 5B is welded using open U-shaped stirrups after bending, the weld length must be no less than 12d (d is the bar diameter, the same below), and the effective weld length for a full weld must be no less than 10d. If lap joints are used, the lap ratio must be 50% and the lap length must be 56d. The lapped reinforcement must be tightly aligned to ensure a good lap. Additional U-shaped reinforcement or closed ring hoops may be used as necessary for securing. Closed stirrup 5A should be closed with a 90° hook, and the straight section after bending must be no less than 12d.

[0054] When connected to a steel beam, the requirements for ring beam stirrups are as follows: If open stirrups 5B are welded using open U-shaped stirrups after bending, the weld length must be no less than 12d, and the effective weld length must be no less than 10d. If overlapped, the overlap ratio must be 100% and the overlap length must be 64d. Closed stirrups 5A must also be overlapped, with a 100% overlap ratio and a 64d overlap length. The overlapping reinforcement must be closely spaced to ensure a secure connection. If necessary, additional fixing structures such as U-shaped bars or closed ring hoops may be added.

[0055] Furthermore, the cantilevered H-beam connected to the steel beam is made of Q355C steel and is connected to the CFST column using groove welds. The flange thickness of the cantilevered H-beam is the same as that of the connecting steel beam, and the web thickness is the web thickness of the connecting steel beam plus 2 mm. Holes are opened within a certain range of the web height to allow for the passage of the upper and lower ring beam reinforcement, waist reinforcement, and structural reinforcement.

[0056] In the above technical solution, the shear bearing capacity of the annular steel corbel is calculated according to the following formula:

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] Where: V u1 - shear capacity determined by the local compressive strength of the concrete on the annular corbel support surface; V u2 — shear bearing capacity determined by the shear strength of the ribs; V u3 — Shear bearing capacity determined by the welding strength between the rib and the tube wall; V u4 - Shear bearing capacity determined by the direct shear (or punching shear) strength of the concrete above the annular corbel; V u5 ——The shear bearing capacity determined by the upper and lower ring plates of the annular corbel; β 2——Increase coefficient of local compressive strength of concrete, β 2 can be taken as 1; D ——outer diameter of the steel pipe; b —Width of ring plate; l —height of the straight shear surface; t —Thickness of the ring plate; n — number of ribs; h w - height of ribs; tw —thickness of ribs; f v ——Design value of shear strength of steel; f a ——Design value of tensile (compressive) strength of steel; ∑ l w —Calculated total length of fillet welds connecting ribs and steel pipe walls; h e ——Effective height of fillet weld; f f w —Design value of shear strength of fillet weld; f c ——design value of concrete compressive strength; f t ——Design value of concrete tensile strength.

[0063] In the above technical solution, the calculation method of reinforced concrete ring beam node reinforcement is as follows: When the diameters of the annular reinforcements in the upper portion of the ring beam are the same and the horizontal spacing is equal, the area of ​​the tensioned ring reinforcement and the area of ​​a single stirrup in the ring beam shall comply with the following requirements: 1 When the beneficial effect of the floor slab is not considered, the calculation should be carried out according to the following formula:

[0064]

[0065] 2 When considering the beneficial effect of the floor slab, the calculation should be carried out according to the following formula:

[0066]

[0067]

[0068]

[0069]

[0070] Among them, under the action of negative bending moment, β 1 takes 0.5, β 2 takes 0.65, β 3 is taken as 0.6; taken under the action of positive bending moment β 1= β 2= β 3=1.0; i 1——The central angle corresponding to the projection length of the frame beam on the outer edge of the ring beam, see Figure 6 ; i 2 – the central angle corresponding to the projected length of the upper surface crack on the outer edge of the ring beam when the ring beam fails; α 0——the central angle corresponding to the projected length of the side crack on the outer edge of the ring beam when the ring beam is damaged; R ——Ring beam radius, i.e. the radial distance from the edge of the ring beam to the center of the steel pipe; r ——radius of steel pipe; 3 The area of ​​a single stirrup of the ring beam should be calculated according to the following formula:

[0071] Where: l ——Shear-ring ratio, which is the ratio of the nominal tension of the ring beam stirrups to the nominal tension of the tension ring bars of the ring beam. l = F v / F h , which can be 0.35~0.7. When the effect of floor 16 is not considered, a higher value is taken, and when the effect of floor slab is considered, a lower value is taken. F h ——nominal tension of the tension ring reinforcement (N), F h = 0.7 f yh A sh ; f yh ——Design value of tensile strength of hoop reinforcement (MPa); A sh ——Cross-sectional area of ​​circumferential reinforcement (mm 2 ); F v ——nominal tension of ring beam stirrups (N), F h = α v A sv f yv / c H ; f yv——Design value of stirrup tensile strength (MPa); c H ——the angle between stirrups (radians), c H = S / ( r + b h / 2); S ——Stirrup spacing at the center line of the ring beam (mm); A sv ——Area of ​​single stirrup of ring beam (mm 2 ); α v ——Calculation coefficient of closed stirrups; M k ——Bending moment of the frame beam end calculated from the actual reinforcement (N•mm); α dp ——Test correction coefficient, take α dp =1.3; h r ——height of the ring beam section (mm); h r0 ——Effective height of ring beam section (mm); b k ——Width of the frame beam connected to the ring beam (mm).

[0072] When the strength grade of the ring beam's annular reinforcement is the same as that of the frame beam, the diameter of the annular reinforcement is the same, and the horizontal spacing is equal, the area of ​​the ring beam's tension reinforcement and the area of ​​a single stirrup can be calculated using the following formula: 1 When the floor effect is not considered:

[0073]

[0074] 2 When considering the floor effect:

[0075]

[0076] Where: A sk ——Area of ​​tensile reinforcement at the end of frame beam (mm 2 ); f y —Design value of tensile strength of annular reinforcement of ring beam (MPa); A sv ——Area of ​​single stirrup of ring beam stirrup (mm 2 ); f yv ——design value of tensile strength of stirrups (MPa); c H ——the angle between stirrups (radians); α v ——Calculation coefficient of closed stirrups.

[0077] Compared with the existing CFST column frame node, the present invention solves the following problems: 1. Low shear bearing capacity in the node area In high-rise buildings, if CFST columns are subjected to bending or large eccentric compression under earthquake or wind loads, the structure exhibits strong ductility during failure. Conversely, if subjected to large shear forces, the structure typically fails brittlely. The annular steel corbels described in this invention enhance the shear bearing capacity of the joint area, meeting the design concept of "strong shear, weak bending."

[0078] 2. The force transmission path in the node area is not direct CFST column joints are characterized by a high number of steel bars and complex loads. Through-hole or welded longitudinal reinforcement cannot effectively transmit the internal forces at the beam ends. This is especially true in moderate to severe earthquakes, where unbalanced negative bending moments at the beam ends can accelerate joint failure. The reinforced concrete ring beam described in this invention effectively transmits bending moments and axial forces at the beam ends, providing a clear and reliable force transmission path.

[0079] 3. Inconvenient construction and heavy on-site welding workload On-site drilling and welding of CFST columns is labor-intensive and difficult to ensure weld quality. The cantilever H-shaped steel beams described in this invention require only a small number of holes in the web, with both drilling and welding completed in the factory. On-site connections require only high-strength bolts, with minimal welding required, making construction efficient and convenient.

[0080] 4. Limited and not economical Reinforced concrete beams located in large cantilever locations typically have large diameters and numerous steel bars, resulting in large cross-sections and poor economic efficiency. The node disclosed in this invention can simultaneously connect steel beams and reinforced concrete beams, effectively leveraging the load-bearing capacity of reinforced concrete frame beams while effectively utilizing the physical and mechanical properties of cantilevered steel beams, achieving a balance between rationality and economy.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A steel tube concrete column frame node connecting steel beams and reinforced concrete beams at the same time, characterized in that: include: Concrete-filled steel tube columns (13), reinforced concrete beams (9), and steel beams (10); An annular steel corbel welded to the outside of a steel tube concrete column, the annular steel corbel comprising an upper reinforcement ring (7), a lower reinforcement ring (7A), and a rib plate (8) connecting the upper reinforcement ring (7) and the lower reinforcement ring (7A); A reinforced concrete ring beam is arranged around the steel tube concrete column, wherein the reinforced concrete ring beam is an annular reinforced concrete structure centered on the steel tube concrete column and supported by an upper reinforcement ring (7) and a lower reinforcement ring (7A); in: The lower longitudinal reinforcement (6) of the reinforced concrete beam (9) is anchored to an anchor plate (15) fixed below the lower reinforcement ring (7A), and the upper longitudinal reinforcement (14) of the reinforced concrete beam (9) extends into the opposite side of the reinforced concrete ring beam and bends downward; The steel beam (10) is connected to a cantilever H-shaped steel beam (11) via high-strength bolts (17); the cantilever H-shaped steel beam (11) is welded to a steel tube concrete column (13) and has a web opening; an inner column partition (12) is provided inside the steel tube concrete column (13) at the same height as the upper flange of the cantilever H-shaped steel beam (11); The steel bars of the reinforced concrete ring beam pass through the holes in the web of the cantilever H-shaped steel beam (11).

2. The framework node according to claim 1, characterized in that: The thickness of the upper reinforcement ring (7) is 20 mm, the thickness of the lower reinforcement ring (7A) is 20 mm, and the thickness of the rib plate (8) is ≥ 20 mm; The lower reinforcement ring (7A) is provided with exhaust holes with a diameter of ≥50 mm at intervals of 45° along the circumferential direction.

3. The framework node according to claim 1, characterized in that: When connected to a reinforced concrete beam (9), the reinforced concrete ring beam comprises closed stirrups (5A) and open stirrups (5B); The closed stirrup (5A) is closed with a 90° hook, and the straight section length after bending is not less than 12d; The open stirrups (5B) are formed by bending and welding U-shaped stirrups, with a welding length of ≥12d; or by overlapping, with an overlapping rate of 50% and an overlapping length of 56d.

4. The framework node according to claim 1, characterized in that: When connected to the steel beam (10), the reinforced concrete ring beam comprises closed stirrups (5A) and open stirrups (5B); The closed stirrups (5A) are connected by overlapping, with an overlapping rate of 100% and an overlapping length of 64d; The open stirrups (5B) are formed by bending and welding U-shaped stirrups, with a welding length of ≥12d; or by overlapping, with an overlapping rate of 100% and an overlapping length of 64d.

5. The framework node according to claim 1, characterized in that: The height of the cantilever H-shaped steel beam (11) is equal to the height of the connecting steel beam (10), and the length of the cantilever H-shaped steel beam (11) is greater than or equal to the height of the connecting steel beam (10); The flange thickness of the cantilever H-shaped steel beam (11) is equal to the flange thickness of the connecting steel beam (10), and the web thickness of the cantilever H-shaped steel beam (11) is the web thickness of the connecting steel beam (10) + 2 mm.

6. The framework node according to claim 1, characterized in that: The reinforced concrete ring beam comprises: The upper reinforcement of the ring beam (1) is arranged in the area above the upper reinforcement ring (7); The lower reinforcement of the ring beam (2) is arranged in the area below the lower reinforcement ring (7A); The ring beam waist reinforcement (3) and the structural reinforcement (4) are arranged from the outside of the annular steel corbel to the edge of the ring beam; Ring beam stirrups (5), including closed stirrups (5A) and open stirrups (5B).

7. The framework node according to claim 6, characterized in that: A 90° hook is provided at the closed portion of the closed stirrup (5A), and the straight length of the hook is ≥12d.

8. A method for designing a framework node according to any one of claims 1 to 7, characterized in that: include: Calculation of shear capacity of circular steel corbel: Where: V u1 - shear capacity determined by the local compressive strength of the concrete on the annular corbel support surface; V u2 — shear bearing capacity determined by the shear strength of the ribs; V u3 — Shear bearing capacity determined by the welding strength between the rib and the tube wall; V u4 - shear capacity determined by the direct shear or punching shear strength of the concrete above the annular corbel; V u5 ——The shear bearing capacity determined by the upper and lower ring plates of the annular corbel; β 2——Increase coefficient of local compressive strength of concrete, β 2 can be taken as 1; D ——outer diameter of the steel pipe; b —Width of ring plate; l —height of the straight shear surface; t —Thickness of the ring plate; n — number of ribs; h w - height of ribs; t w —thickness of ribs; f v ——Design value of shear strength of steel; f a — design value of tensile or compressive strength of steel; ∑ l w —Calculated total length of fillet welds connecting ribs and steel pipe walls; h e ——Effective height of fillet weld; f f w —Design value of shear strength of fillet weld; f c ——design value of concrete compressive strength; f t ——Design value of concrete tensile strength.

9. The design method according to claim 8, characterized in that: It also includes the calculation of the tension ring reinforcement area of ​​the ring beam: When the diameters of the annular reinforcements in the upper portion of the ring beam are the same and the horizontal spacing is equal, the area of ​​the tensioned ring reinforcement and the area of ​​a single stirrup in the ring beam shall comply with the following requirements: 1) When the beneficial effect of the floor slab is not considered, the calculation should be carried out according to the following formula: 2) When considering the beneficial effect of the floor slab, the calculation should be carried out according to the following formula: ； Among them, under the action of negative bending moment, β 1 takes 0.5, β 2 takes 0.65, β 3 is taken as 0.6; taken under the action of positive bending moment β 1= β 2= β 3=1.0; θ 1 – the central angle corresponding to the projection length of the frame beam on the outer edge of the ring beam; θ 2 – the central angle corresponding to the projected length of the upper surface crack on the outer edge of the ring beam when the ring beam fails; α 0——the central angle corresponding to the projected length of the side crack on the outer edge of the ring beam when the ring beam is damaged; R ——Ring beam radius, i.e. the radial distance from the edge of the ring beam to the center of the steel pipe; r ——radius of steel pipe; 3) Calculate the area of ​​a single stirrup: Where: λ ——Shear-ring ratio, which is the ratio of the nominal tension of the ring beam stirrups to the nominal tension of the tension ring bars of the ring beam. λ = F v / F h , which can be 0.35~0.

7. Take the higher value when the effect of the floor is not considered, and take the lower value when the effect of the floor is considered; F h ——nominal tension of the tension ring reinforcement (N), F h = 0.7 f yh A sh ; f yh ——Design value of tensile strength of hoop reinforcement (MPa); A sh ——Cross-sectional area of ​​circumferential reinforcement (mm 2 ); F v ——nominal tension of ring beam stirrups (N), F h = α v A sv f yv / γ H ; f yv ——Design value of stirrup tensile strength (MPa); γ H ——the angle between stirrups (radians), γ H = S / ( r + b h / 2); S ——Stirrup spacing at the center line of the ring beam (mm); A sv ——Area of ​​single stirrup of ring beam (mm 2 ); α v ——Calculation coefficient of closed stirrups; M k ——Bending moment of the frame beam end calculated from the actual reinforcement (N•mm); α dp ——Test correction coefficient, take α dp =1. 3; l r ——The moment arm from the point of action of the resultant force of the tension ring reinforcement of the ring beam to the resultant force point of the compression zone is taken as min{0.87 h r0 , h r -50}; h r ——height of the ring beam section (mm); h r0 ——Effective height of ring beam section (mm); b k ——Width of the frame beam connected to the ring beam (mm).

10. The design method according to claim 8, characterized in that: It also includes the calculation of the tension ring reinforcement area of ​​the ring beam: When the strength grade of the ring beam's annular reinforcement is the same as that of the frame beam, the diameter of the annular reinforcement is the same, and the horizontal spacing is equal, the area of ​​the ring beam's tension reinforcement and the area of ​​a single stirrup can be calculated using the following formula: 1) When the floor effect is not considered: 2) When considering the effect of floor slab: Where: A sk ——Area of ​​tensile reinforcement at the end of frame beam (mm 2 ); f y ——Design value of tensile strength of annular reinforcement of ring beam (MPa).

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