Variable cross-section height embedded steel connector

Abstract

The utility model discloses a variable cross section height embedded type steel connecting piece, including a pair of for non -length embedded beam end flange plate and the web connected between both, the web embedded beam end one section extends to the beam span direction, and forms the extension section of gradually reducing cross section height, this extension section is used for constructing the transition area of the steady change of the bending stiffness continuity in the beam body. The utility model aims at solving the problems of the existing SRC beam technology in the stiffness transition, node construction complexity and connecting mode reliability. By adopting the special variable cross section height design, the steel connecting piece of the utility model can realize the uniform transition of beam end stiffness, effectively avoid the stress concentration and ductility deformation ability drop caused by stiffness mutation. Meanwhile, the structural design of the connecting piece is simple and clear, greatly simplifies the construction requirement of beam end area, reduces the construction difficulty, improves the reliability of node.

Description

Technical Field

[0001] This utility model relates to the technical field of building components, and in particular to a variable cross-section height embedded steel connector. Background Technology

[0002] Steel-concrete composite beams (SRC beams) are a type of high-efficiency structural component. By organically combining steel and concrete, they fully leverage the dual advantages of steel beams (high load-bearing capacity and good ductility) and concrete beams (high stiffness, fire resistance, and durability). This composite structure not only significantly improves the load-bearing capacity and stiffness of components but also effectively enhances the seismic performance of the structure. Therefore, it has been widely used in modern high-rise buildings, large-span spatial structures, and important infrastructure projects.

[0003] Traditional SRC beam designs typically employ a construction method where steel sections are arranged along the entire length of the beam within the concrete beam. This design concept is reflected in several patented technologies. For example, the H-shaped steel arrangement scheme disclosed in "A Wave-Shaped Steel-Concrete Composite Beam" (Patent No. ZL201910179952.7) and the T-shaped steel application method demonstrated in "A Prestressed Steel-Seat T-Shaped Steel-Concrete Composite Beam" (Patent No. ZL201310499946.2) are examples of this approach. In these traditional constructions, the connection nodes between the beam ends and columns are critical components of the entire structural system, and their mechanical properties directly determine the seismic safety and reliability of the overall structure.

[0004] However, existing SRC beam technology still faces several technical challenges that urgently need to be addressed in practical engineering applications: Firstly, there are significant defects in the stiffness transition. The traditional design of continuous steel sections abruptly ending at the beam end section height leads to a sharp change in stiffness from the concrete beam section height to the core area of ​​the joint. This abrupt change in stiffness not only causes significant stress concentration in the joint area but also severely affects the ductility and energy dissipation performance of the joint, thereby reducing the overall seismic performance of the structure.

[0005] Secondly, the joint construction is overly complex. In the beam end area, especially the anchorage treatment of longitudinal reinforcement, multiple construction measures are required, including intensive operations such as rebar perforation and bending. These complex construction requirements not only increase the construction difficulty but also easily affect the reliability of the joint due to difficulties in ensuring construction quality. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this invention is to provide a variable cross-section height embedded steel connector, aiming to solve the issues existing in SRC beam technology regarding stiffness transition, node construction complexity, and connection reliability. By employing a special variable cross-section height design, the steel connector of this invention achieves a uniform transition of beam end stiffness, effectively avoiding stress concentration and decreased ductility caused by abrupt stiffness changes. Simultaneously, the connector's structural design is simple and clear, greatly simplifying the construction requirements of the beam end area, reducing construction difficulty, and improving node reliability. Furthermore, this invention, through an innovative connection method, further enhances the stability and seismic performance of beam-column connections, providing strong support for the optimized design of modern building structures.

[0007] To achieve the above objectives, this utility model discloses a variable cross-section height embedded steel connector, the key of which is: it includes a pair of flange plates for non-continuous embedding into the beam end, and a web plate connecting the two; a section of the web plate embedded into the beam end extends toward the mid-span of the beam and forms an extension section with a gradually decreasing cross-sectional height; this extension section is used to construct a transition region in the beam body where the bending stiffness changes continuously and smoothly.

[0008] Furthermore, at least a portion of the cross-sectional height of the extension exhibits a linear or non-linear variation.

[0009] Furthermore, the overall cross-sectional height of the extension section varies linearly, with its upper and lower edges extending obliquely and converging relatively to form a wedge-shaped structure.

[0010] Furthermore, a through groove is pre-reserved on a section of the web plate embedded at the beam end, which is used to realize the through arrangement of tie bars.

[0011] Furthermore, fixing holes are provided on the surface of the web plate where it is not embedded in the beam end, and these fixing holes are used to install high-strength bolts.

[0012] Furthermore, a beam end steel plate is provided between the flange plates. The plate size of the beam end steel plate is adapted to the beam end face. On the one hand, it serves as the end template for the beam casting, and on the other hand, it serves as the cut-off plate for the flange plates and the web plates to be embedded.

[0013] Furthermore, a steel pad is provided on each of the flange plates and / or the web plates and / or the beam end plates, the steel pads being used to connect the beam reinforcement to transfer the load.

[0014] Compared with the prior art, the significant advantages of this utility model are: (1) After the steel connector is embedded to a predetermined depth (not continuous length) at the beam end, its flange stops penetrating, while the web continues to extend a distance towards the mid-span of the beam. In the extended section of the web, its cross-sectional height gradually decreases in a linear or nonlinear manner, eventually forming a small residual cross-sectional height. This design constructs a stiffness buffer / transition zone, the core objective of which is to achieve a continuous and smooth transition of the flexural stiffness of the beam cross-sectional height from the pure concrete region to the region containing the complete steel section, avoiding stress concentration caused by abrupt changes and delaying crack propagation. In this region, concrete cracks appear later, are more dispersed and finer, which helps to maintain the contribution of concrete and makes the overall stiffness degradation more gradual. At the same time, this design can also improve hysteresis performance. The smoother stiffness change and reduced stress concentration help to obtain a fuller hysteresis curve with less pinching effect, which means that the structure has a stronger energy dissipation capacity and a smaller degree of stiffness / strength degradation.

[0015] (2) In terms of structural design, the steel connectors are not embedded in the beam along its entire length. This not only simplifies the construction of the composite beam but also avoids the complexity caused by the continuous arrangement of steel along the beam in traditional designs. This design not only significantly reduces the amount of steel used and lowers costs but also makes the assembly and welding work during construction simpler and more efficient. At the same time, the simple and clear structure of the steel connectors greatly reduces errors and uncertainties during construction, improving the reliability of the joints and the safety of the overall structure. On the other hand, the steel connectors bear the load through the flange plates, simplifying the detailed design of the beam end area and reducing the cumbersome construction of densely opening holes on the steel flanges or complex bending of the reinforcing bars. This simple structural design not only reduces the difficulty of construction and improves construction efficiency but also reduces potential reliability issues at the joints due to construction quality problems. Meanwhile, the through slots reserved on the web facilitate the through arrangement of tie bars, further improving the connection performance of the joints.

[0016] (3) Regarding the connection method, this utility model employs an innovative design of fixing holes and steel pads. The fixing holes in the web portion not embedded in the beam end are used to install high-strength bolts. This connection method not only facilitates construction but also has the ability to slip and deform, dissipating some seismic energy and meeting the requirements of seismic performance. At the same time, steel pads are selectively set on the flange plate, web plate, and beam end steel plate, providing reliable force transmission points for the connection of beam reinforcement and further enhancing the stability of the beam-column connection. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the variable cross-section height embedded steel connector in Embodiment 1; Figure 2 This is a schematic diagram of the overall structure of the variable cross-section height embedded steel connector in Embodiment 2 (I); Figure 3 This is a schematic diagram of the overall structure of the variable cross-section height embedded steel connector in Embodiment 2 (II); Figure 4 This is a diagram showing the usage status of the variable cross-section height embedded steel connector in Example 1; The numbers in the diagram are: 1-flange plate, 2-web plate, 3-extension section, 4-through groove, 5-fixing hole, 6-beam end steel plate, 7-steel pad plate. Detailed Implementation

[0019] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0020] In the description of this utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] Figure 1The first embodiment of this utility model is disclosed: a variable cross-section height embedded steel connector, including a pair of flange plates 1 for non-continuous embedding into the beam end, and a web plate 2 connecting the two; a section of the web plate 2 embedded in the beam end extends towards the mid-span of the beam, forming an extension section 3 with a gradually decreasing cross-section height; this extension section 3 is used to construct a transition region in the beam body with a continuous and smooth change in bending stiffness. The design of the extension section 3 creates a smooth transition between the beam end and the region containing the complete steel section, effectively avoiding the problem of abrupt stiffness changes in traditional SRC beam design. This variable cross-section height design not only improves the overall seismic performance of the structure, but also significantly enhances the ductility and energy dissipation performance of the joint.

[0022] In specific implementation, at least a portion of the cross-sectional height of the extension segment 3 exhibits linear or nonlinear variations. In this embodiment, preferably, the overall cross-sectional height of the extension segment 3 varies linearly, with its upper and lower edges extending obliquely and converging to form a wedge-shaped structure. This wedge-shaped structure design further enhances the smoothness of the transition region, making the change in bending stiffness more uniform, thereby further optimizing the seismic performance of the structure. In other embodiments, the overall cross-sectional height of the transition segment may also vary nonlinearly, or a combination of linear and nonlinear variations may be used to meet specific engineering requirements or optimize structural performance. Furthermore, using nonlinear variations, or a combination of nonlinear and linear variations in cross-sectional height design, may involve more complex geometries and manufacturing processes. However, in some cases, this design can provide superior performance compared to linear variations. For example, under certain specific dynamic response or load conditions, it can more effectively disperse stress and energy.

[0023] Specifically, the embedment depth of the steel connectors, the stopping position of flange plate 1, the length of web plate 2 and extension section 3, and the gradient slope of extension section 3 are determined according to construction requirements. In actual engineering, these parameters can be refined based on construction experience and factors such as beam span and load magnitude. For beams with larger spans and heavier loads, the length of extension section 3 can be appropriately increased, and the gradient slope can be correspondingly reduced to ensure a smoother transition in bending stiffness. When determining the embedment depth, the stress conditions at the beam ends must be fully considered to ensure that flange plate 1 and web plate 2 can effectively transfer the load to the beam structure.

[0024] In one embodiment, the flange 1 of the steel connector is located at a distance from the end face of the beam. The embedding stops at point 2; the web plate 2 continues to extend its length. Extension segment 3, forming a gradient slope at both the upper and lower edges. The transition region, whose geometric parameters satisfy the relation （Ⅰ） : ...............（Ⅰ） In the formula: : Clear span of the beam; The distance between the end of flange plate 1 and the end of the beam; : Extension segment 3 length; The total length from the end of the beam to the end of extension section 3; : Starting height of extension section 3; Total height of the beam section; Distance from the wing edge stopping position Web height at the location; : Remaining cross-sectional height at the end of extension segment 3; : Web extension coordinates, with the positive direction pointing towards the mid-span of the beam, and the origin located at the position where flange plate 1 stops embedding; : Gradual slope of extension segment 3; The ratio of the extension length of extension segment 3 to the insertion stop position of the first flange; The ratio of the minimum embedment depth of flange 1 to its span; The ratio of the residual height of extension segment 3 to the initial height of the web; The ratio of the remaining height of extension section 3 to the height of the beam; Span utilization rate coefficient ; : Gradual slope adjustment factor for load response; Regarding uniformly distributed loads A monotonically increasing function; : Design value of maximum bending moment at mid-span of the beam; : Yield strength of steel; Design value of uniformly distributed load on beam.

[0025] The application of the aforementioned geometric parameter relationships is of great significance in practical engineering. When determining these parameters, factors such as the beam's clear span and the design value of the uniformly distributed load must be comprehensively considered. By calculating and applying these relationships, reasonable geometric parameters can be accurately determined for steel connectors, thereby ensuring their optimal mechanical performance within the beam.

[0026] For example, when the beam has a large clear span or a high design value for the uniformly distributed load, it is necessary to appropriately increase the embedment depth of the flange plate 1 and the length of the extension section 3 according to the relationship to ensure that the beam has sufficient bending resistance and stability. At the same time, the adjustment of the gradual slope also needs to be accurately calculated according to the actual situation to ensure that the change in bending stiffness in the transition area meets the design requirements.

[0027] Taking the standard floor frame beam of a high-rise office building as an example, the relationship is... （Ⅰ） Verification required: 1. Design input parameters: beam clear span (Structural axis spacing minus support width); Beam section height (Dimensions indicated on the structural construction drawings); Uniformly distributed load design value (Including the combined values ​​of dead load and live load); Maximum bending moment at mid-span (Calculation results from structural analysis software); steel yield strength (Measured values ​​using Q390 grade steel); Extension 3 starting height (Specifications of HN550×200 steel section).

[0028] 2. Explanation of coefficient values:

[0029] 3. Parameter calculation process: (1) Determine the stopping position of flange 1 : ; Values: ; Note: Meets seismic anchorage requirements ( ); satisfying moment transfer ( ).

[0030] (2) Determine the web extension length : ; Note: Coefficient Achieve efficient transition of short extension segment 3.

[0031] (3) Determine the total length from the end of the beam to the end of extension section 3. : ; Validation constraints: .

[0032] (4) Determine the stiffness adjustment coefficient : ; Note: Logarithmic function response to load intensity, Corresponds to a moderately gradual slope.

[0033] (5) Determine the unilateral cutting slope : ; Note: Slope is positively correlated with load. It is inversely correlated with span.

[0034] (6) Determine the web height function : ; Key points: ; .

[0035] (7) Determine the height of the residual section : ; Validation constraints: ; (8) Total length of H-beam : ; The beam end extends 200mm outward for column node 4 connection: .

[0036] 4. Cutting rules for extension segment 3: Cutting line on the top edge of the plate: ; Cutting line on the bottom edge: .

[0037] 5. Beam Structure Implementation and Zoning: |← Left section steel-covered area→|← Middle concrete area→|← Right section steel-covered area→| 0 ─────── 3055mm ─────── 4945mm ────── 8000mm; The complete area of ​​flange plate 1 and web plate 2 in the beam: 0 ~ 2350mm (flange + web); The gradient zone of extension section 3: 2350 ~ 3055 mm (the cross-sectional height of extension section 3 is 550 → 469 mm); Central concrete zone: 3055~4945 mm (pure concrete section); Symmetry: The two covered areas are of equal length (3055 mm each) and their midpoints are aligned.

[0038] 6. Implementation Results: (1) The stress concentration factor was reduced from 2.8 in the traditional design to 1.5; (2) Steel usage is reduced by 28% (compared to continuous arrangement); (3) Construction time for key nodes is reduced by 35%; (4) The rotational capacity of the plastic hinge is increased to 0.032 rad (meeting the seismic requirements of high intensity areas).

[0039] In this embodiment, a through groove 4 is pre-reserved on a section of the web 2 embedded at the beam end. This through groove 4 is used to facilitate the through-layout of tie bars. This design not only simplifies the arrangement of tie bars but also enhances the connection strength between the web 2 and the concrete beam, further improving overall performance. Furthermore, the through groove 4 facilitates concrete pouring, helping to ensure dense filling of concrete around the web 2, thereby enhancing the integrity and durability of the structure. In practical implementation, the shape, size, and position of the through groove 4 can be optimized according to actual engineering needs to achieve the best connection effect and construction convenience. On the other hand, the section of the web 2 with the through groove 4 can also, to some extent, disperse stress and energy, further improving seismic performance in conjunction with the variable cross-section design.

[0040] Specifically, fixing holes 5 are provided on the surface of the web 2 where it is not embedded in the beam end. These fixing holes 5 are used to install high-strength bolts. This high-strength bolt connection method is not only simple and quick to install, but also has high connection stiffness and seismic performance. The high-strength bolts achieve a friction-type connection of the connectors with the help of pre-tightening force, which facilitates construction positioning and adjustment, and can effectively transfer shear force and bending moment, ensuring the stability of the beam-column connection.

[0041] Figures 2 to 4The second embodiment of this utility model is shown. Based on the first embodiment, a beam end steel plate 6 is further provided between the flange plates 1. The plate size of the beam end steel plate 6 is adapted to the beam end face, serving as both an end template for beam casting and a stop plate for the embedding of the flange plates 1 and the web plates 2. The beam end steel plate 6 is integrally formed with the flange plates 1 and the web plates 2 or connected and fixed by welding, ensuring the stability and integrity of the connector. During beam casting, the beam end steel plate 6, as an end template, effectively prevents concrete leakage and ensures casting quality. Simultaneously, as a stop plate, the beam end steel plate 6 limits the embedding depth of the flange plates 1 and the web plates 2 within the beam, ensuring the connector functions as designed.

[0042] In practical implementation, steel pads 7 are respectively provided on each of the flange plates 1 and / or the web plates 2 and / or the beam end plates 6. The steel pads 7 are used to connect the beam reinforcement to transfer force. The steel pads 7 further enhance the connection strength between the connectors and the beam reinforcement, ensuring the continuity and effectiveness of force transmission. In practical implementation, the shape, size, and installation position of the steel pads 7 can also be optimized according to actual engineering needs to achieve the best connection effect and load-bearing performance. The steel pads 7 can be fixed to the flange plates 1, web plates 2, or beam end plates 6 by welding, bolting, or other reliable connection methods to ensure their stability and durability.

[0043] It is worth mentioning that the variable cross-section height embedded steel connector of this utility model is not only suitable for traditional SRC beam structures, but can also be widely used in other types of composite beam structures. Its unique variable cross-section height design and simple construction requirements enable the connector to perform excellently in different types of composite beam structures, effectively improving the overall load-bearing capacity and seismic performance.

[0044] In summary, after the steel connector of this invention is embedded to a predetermined depth (not continuous length) at the beam end, its flange stops penetrating, while the web 2 continues to extend a distance towards the mid-span of the beam. In the extension section 3 of the web 2, its cross-sectional height gradually decreases in a linear or nonlinear manner, ultimately forming a smaller residual cross-sectional height. This design constructs a stiffness buffer / transition zone, the core objective of which is to achieve a continuous and smooth transition of the beam's cross-sectional height from the pure concrete region to the region containing the complete steel section, avoiding stress concentration caused by abrupt changes and delaying crack propagation. In this region, concrete cracks appear later, are more dispersed and finer, which helps maintain the contribution of concrete and makes the overall stiffness degradation more gradual. At the same time, this design also improves hysteresis performance. A smoother stiffness change and reduced stress concentration contribute to a fuller hysteresis curve with less pinching effect, which means that the structure has a stronger energy dissipation capacity and a smaller degree of stiffness / strength degradation. In terms of structural design, the steel connectors are not embedded continuously into the beam, which not only simplifies the construction of the composite beam but also avoids the complexity caused by the continuous arrangement of steel along the beam in traditional designs. This design not only significantly reduces the amount of steel used and lowers costs but also makes assembly and welding during construction simpler and more efficient. At the same time, the simple and clear structure of the steel connectors greatly reduces errors and uncertainties during construction, improving the reliability of the joints and the safety of the overall structure. Furthermore, the steel connectors bear the load through the flange plate 1, simplifying the detailed design of the beam end area and reducing the cumbersome construction of densely perforated flanges or complex bending of reinforcing bars. This simple structural design not only reduces construction difficulty and improves construction efficiency but also reduces potential reliability issues at the joints due to construction quality problems. Meanwhile, the through groove 4 reserved on the web plate 2 facilitates the through arrangement of tie bars, further improving the connection performance of the joint. In terms of connection method, this utility model utilizes an innovative design of fixing holes 5 and steel pads 7. The fixing holes 5 in the portion of the web 2 not embedded in the beam end are used to install high-strength bolts. This connection method not only facilitates construction but also has the ability to slip and deform, dissipating some seismic energy and meeting the requirements for seismic performance. At the same time, steel pads 7 are selectively set on the flange plate 1, web 2, and beam end steel plate 6, providing reliable force transmission points for the beam reinforcement connection and further enhancing the stability of the beam-column connection.

[0045] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present utility model are still within the scope of the utility model.

Claims

1. A variable cross-section height embedded section connecting member, characterized by: It includes a pair of flanges for non-continuous embedding into the beam ends, and a web connecting the two; a section of the web embedded into the beam ends extends toward the mid-span of the beam and forms an extension with a gradually decreasing cross-sectional height; this extension is used to create a transition region in the beam where the bending stiffness changes continuously and smoothly.

2. The variable cross-section height embedded section steel connector of claim 1, wherein: At least a portion of the cross-sectional height of the extension section varies linearly or nonlinearly.

3. The variable cross-section height embedded section steel connector of claim 2, wherein: The overall cross-sectional height of the extension section varies linearly, with its upper and lower edges extending obliquely and converging relatively to form a wedge-shaped structure.

4. The variable cross-section height embedded section steel connector of claim 1, wherein: A through groove is pre-reserved on a section of the web plate embedded at the beam end, which is used to realize the through arrangement of tie bars.

5. The variable cross-section height embedded section steel connector of claim 4, wherein: Fixing holes are provided on the surface of the web portion not embedded in the beam end, and the fixing holes are used to install high-strength bolts.

6. A variable cross-section height embedded section steel connector according to any one of claims 1-5, characterized in that: A beam end steel plate is also provided between the flange plates. The plate size of the beam end steel plate is adapted to the beam end face. On the one hand, it serves as the end template for the beam casting, and on the other hand, it serves as the cut-off plate for the flange plate and the web plate to be embedded.

7. The variable cross-section height embedded section steel connector of claim 6, wherein: Each of the flange plates and / or the web plates and / or the beam end plates is provided with a steel pad, which is used to connect the beam reinforcement to transfer the force.

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