Self-resetting beam-column connection for weak-axis direction of column

Abstract

This invention proposes a self-resetting beam-column connection node for the weak axis direction of a column, belonging to the field of seismic resistance technology for building structures. The node includes a column, a beam, a cover plate, and a shape memory alloy Ω-shaped damper. The upper flange of the beam is seamlessly connected to the upper stiffening rib of the column via the cover plate, allowing the beam to rotate around the upper flange end, preventing separation of the upper flange and effectively protecting the floor slab. A gap is reserved between the lower flange of the beam and the lower stiffening rib of the column, providing deformation space for the Ω-shaped damper placed within the gap. Furthermore, the thickness of the U-shaped section of the Ω-shaped damper is designed to be less than the thickness of the straight connection section, ensuring that deformation is concentrated in the U-shaped section of the damper, while the main beam and column remain elastic, achieving damage control. The hyperelastic properties of the shape memory alloy enable the damper to automatically reset while dissipating energy, significantly reducing residual deformation after an earthquake. This invention has the advantages of being easily assemblable and maintainable.

Description

Technical Field

[0001] This invention relates to a self-resetting beam-column joint for use in the weak axis direction of a column, belonging to the field of seismic engineering technology. Background Technology

[0002] Brittle failure of beam-column joints during earthquakes is one of the main causes of steel structure failure. Existing ductile joints dissipate energy through plastic deformation, but produce significant residual deformation that is difficult to repair after an earthquake, often forcing structural demolition and causing huge economic losses. To address the residual deformation problem, self-resetting technology uses materials such as post-tensioned prestressed tendons or shape memory alloys to restore the joint to its original position after an earthquake. However, existing research on self-resetting joints mainly focuses on the strong axis direction of the column, with very limited research on the weak axis direction.

[0003] While existing column-weak-axis beam-column connections offer good ductility and energy dissipation capacity, their energy dissipation mechanism relies on the plastic development of the material, leading to significant residual deformation. The nonlinear behavior of weak-axis connections is distributed across multiple locations within the beams, columns, and connection zones, resulting in complex post-earthquake damage that is difficult to assess and repair quickly. More importantly, the structural characteristics of weak-axis connections easily lead to frame expansion, which in turn causes severe damage to the floor slabs, affecting the overall functionality of the structure and its post-earthquake repairability.

[0004] Therefore, there is an urgent need to develop a beam-column connection node that is suitable for the weak axis direction of the column and has both good energy dissipation capacity and self-resetting function, so as to solve the problems of large residual deformation after earthquake, easy to cause frame expansion and floor damage, and complex damage distribution that is difficult to repair in the existing beam-column connection node with weak axis. Summary of the Invention

[0005] The purpose of this invention is to provide a novel self-resetting beam-column connection node for the weak axis direction of the column, so as to solve the defects of existing beam-column connection nodes in the weak axis direction that lack self-resetting capability, cause floor slab damage after frame expansion, and have complex damage distribution that is difficult to repair.

[0006] The present invention adopts the following technical solution: a self-resetting beam-column connection node for the weak axis direction of a column, comprising: a column, a beam, a cover plate and at least one shape memory alloy Ω-shaped damper; The column is provided with an upper stiffening rib and a lower stiffening rib; the end of the beam is connected to the column; there is no gap between the upper flange of the beam and the column, and there is a gap between the lower flange of the beam and the column; the cover plate is used to connect the upper flange of the beam and the upper stiffening rib; The shape memory alloy Ω-shaped damper is disposed between the lower flange of the beam and the lower stiffening rib of the column; the shape memory alloy Ω-shaped damper includes a U-shaped segment and straight connecting segments respectively connected to both ends of the U-shaped segment; the center line of the U-shaped segment is arc-shaped, and the thickness of the U-shaped segment is less than the thickness of the straight connecting segments; the straight connecting segments are respectively fixed to the lower flange of the beam and the lower stiffening rib of the column; the U-shaped segment is disposed in the gap between the lower flange of the beam and the column.

[0007] Preferably, both the column and the beam are wide-flange cross-section members.

[0008] Preferably, both the upper stiffening rib and the lower stiffening rib are horizontal through stiffening ribs welded to the column, and are precisely aligned with the upper and lower flanges of the beam, respectively.

[0009] Preferably, the column is further provided with vertical stiffening ribs, which connect the upper stiffening ribs and the lower stiffening ribs.

[0010] Preferably, the shape memory alloy Ω-shaped damper is made of nickel-titanium shape memory alloy.

[0011] Preferably, a plurality of shape memory alloy Ω-shaped dampers are provided between the lower flange of the beam and the lower stiffening rib of the column, and are arranged symmetrically with the lower flange of the beam and the web of the beam as axes respectively.

[0012] Preferably, the gap between the lower flange of the beam and the column is equal to the diameter of the U-shaped segment of the Ω-shaped damper.

[0013] Preferably, the cover plate is connected to the upper flange of the beam and the upper stiffening rib using high-strength bolts.

[0014] Preferably, the shape memory alloy Ω-shaped damper is connected to the lower flange of the beam and the lower stiffening rib by high-strength bolts.

[0015] The beneficial effects of this invention are: 1. By constructing a beam with no clearance on the upper flange and clearance on the lower flange, the beam rotates with the end of the upper flange as the center of rotation, concentrating deformation within the Ω-shaped damper on the lower flange. Nonlinear behavior is limited to the replaceable damper, and the main beam and column remain elastic, achieving damage control.

[0016] 2. The gapless design of the upper flange ensures that the upper flange of the beam and the column remain in contact at all times, preventing separation. Since the floor slab is attached above the upper flange of the beam, this design prevents the floor slab from undergoing additional tensile and compressive deformation under lateral deformation, thereby significantly reducing floor slab damage and solving the problem of severe floor slab damage caused by frame expansion in traditional weak axis joints.

[0017] 3. This invention employs a shape memory alloy Ω-shaped damper to transform axial tensile and compressive deformation into U-shaped bending deformation, fully utilizing the superelastic hysteresis characteristics of the shape memory alloy. Within a large deformation range, this connection node can achieve a stable self-resetting hysteresis response, with minimal residual deformation after unloading. Thus, it effectively solves the problem of large residual deformation after earthquakes in existing weak-axis nodes.

[0018] 4. This invention employs a differentiated design where the thickness of the U-shaped segment is less than that of the straight connecting segment. This causes the deformation of the damper to concentrate in the U-shaped segment under stress, while the straight connecting segment maintains high structural stability, ensuring that the shape memory alloy material can fully utilize its hysteresis characteristics within the predetermined energy dissipation area. Efficient and stable energy dissipation can be achieved under both tensile and compressive conditions.

[0019] 5. Both the Ω-shaped damper and the cover plate of the present invention are connected by bolts. After an earthquake, only the Ω-shaped damper needs to be disassembled and replaced to restore the node function. There is no need to repair the main beam and column, which greatly reduces the repair time and cost after the earthquake. Attached Figure Description

[0020] Figure 1 This is a front view of the overall node structure in a specific embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the node structure in a specific embodiment of the present invention. Figure One .

[0022] Figure 3 This is a schematic diagram of the node structure in a specific embodiment of the present invention. Figure Two .

[0023] Figure 4 This is a schematic diagram of a shape memory alloy Ω-shaped damper structure in a specific embodiment of the present invention.

[0024] In the diagram: 1. Column; 2. Beam; 3. Cover plate; 4. Shape memory alloy Ω-shaped damper; 5. Upper stiffening rib; 6. Lower stiffening rib; 7. Vertical stiffening rib. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Other embodiments obtained by those skilled in the art based on the present invention without creative effort are all within the protection scope of the present invention.

[0026] like Figures 1-4 As shown, a self-resetting beam-column connection node for the weak axis direction of a column includes a column 1, a beam 2, a cover plate 3, and at least one shape memory alloy Ω-shaped damper 4.

[0027] Both column 1 and beam 2 adopt a wide flange section; upper stiffening rib 5 and lower stiffening rib 6 are welded on the column, both of which are horizontal through stiffening ribs and are aligned with the upper flange and lower flange of the beam, respectively; in addition, vertical stiffening rib 7 is provided and welded between the two horizontal stiffening ribs to prevent buckling of the horizontal stiffening ribs and improve its stability.

[0028] The upper flange of the beam is connected to the upper stiffening rib 5 of the column through the cover plate 3; the cover plate 3 is connected to the upper flange of the beam and the upper stiffening rib 5 with high-strength bolts; there is no gap between the upper flange of the beam and the column.

[0029] The lower flange of the beam is connected to the lower stiffening rib 6 of the column via at least one shape memory alloy Ω-shaped damper 4. At the beam end, there is a gap between the lower flange and the lower stiffening rib 6, the size of which is equal to the diameter of the U-shaped segment of the shape memory alloy Ω-shaped damper. Viewed from a direction perpendicular to the beam axis, the beam segment has a trapezoidal shape with a longer upper flange and a shorter lower flange. The axial length of the upper flange is equal to the sum of the axial length of the lower flange and twice the diameter of the U-shaped segment of the Ω-shaped damper. This geometry provides sufficient deformation space for the damper. This design ensures that the damper has sufficient deformation space and avoids interference with the surrounding structure during stress.

[0030] The shape memory alloy Ω-shaped damper 4 includes a U-shaped segment and straight connecting segments connected to both ends of the U-shaped segment, and is made of nickel-titanium shape memory alloy; the center line of the U-shaped segment is arc-shaped, which can convert axial tensile and compressive deformation into bending deformation of the U-shaped segment, thereby stimulating the superelastic properties of the shape memory alloy; bolt holes are provided on the straight connecting segments, and the lower flange of the beam and the lower stiffening rib 6 of the column are connected by high-strength bolts.

[0031] In this embodiment, the thickness of the U-shaped segment is less than that of the straight connecting segment. This structural design ensures that when the damper is under stress, the deformation is mainly concentrated in the U-shaped segment, while the straight connecting segment maintains high structural stability, thereby ensuring that the shape memory alloy material can fully utilize its energy dissipation and self-resetting functions.

[0032] The nonlinear behavior of the joint is strictly confined within the Ω-shaped damper, and the beam and column remain in an elastic state throughout. The nonlinear mechanical properties of the entire connection joint are primarily determined by the mechanical behavior of the Ω-shaped damper. By adjusting the key geometric parameters of the damper, its load-bearing capacity can be flexibly designed to meet different engineering requirements. The geometric parameters of the damper include: the radius of the U-shaped segment. r Total height of damper h Thickness of straight connecting section t j Thickness of the arc segment t r Distance from the center of the bolt hole to the mid-surface of the arc segmenta wait.

[0033] Among them, the reasonable design of the damper radius is crucial to the overall performance of the node; if the radius is too small, it will not provide enough space for the beam to rotate, and will cause the deformation mechanism to change from pure bending to bending-tension combination, resulting in a significant increase in damper stiffness, which in turn will cause premature buckling of the beam flange; it is recommended that the damper radius should be greater than 0.082 times the beam height and 2.86 times the damper thickness.

[0034] In addition, by setting multiple dampers symmetrically arranged around the lower flange and web of the beam, the bearing capacity and energy dissipation capacity of the nodes can be flexibly adjusted according to design requirements, while maintaining the structural stress symmetry.

[0035] In this embodiment, the cover plate 3 is made of high-strength steel plate and is fixedly connected to the upper flange of the beam and the upper stiffening rib 5 of the column by bolts. Under gravity load, the cover plate undergoes bending deformation, effectively transferring the vertical load borne by the beam 2 to the column 1; under lateral load, the bending moment generated at the node is borne and dissipated by the Ω-shaped damper of the lower flange, forming a working mechanism that separates the paths of gravity load and seismic load; the cross-sectional dimensions and steel plate thickness of the cover plate are designed to have sufficient strength to resist the action of the bending moment in an elastic state, ensuring that it does not undergo plastic deformation.

[0036] When the structure is subjected to lateral loads, the upper flange end of the beam swings relative to the column with the rotation center as the center. Since the upper flange is connected to the column 1 without gap through the cover plate 3, the upper flange and the column always remain in contact when the beam rotates, avoiding separation between the two, thus effectively protecting the floor slab from crush damage.

[0037] The swaying of the beam causes a change in the gap between the lower flange and the stiffening rib 6 at the bottom of the column, forcing the Ω-shaped damper connected between them to undergo tensile and compressive deformation. When the beam sways upward, the damper is under tension; when it sways downward, the damper is under compression. Its curved sections undergo bending deformation, while the straight connecting sections remain elastic.

[0038] As the load increases, the nonlinear behavior and damage are confined to the arc segment of the Ω-shaped damper, and the beam and column remain in an elastic state, thus achieving damage control. After unloading, the hyperelastic properties of the shape memory alloy cause the damper to automatically return to its initial shape, leading the beam back to its original position and significantly reducing post-earthquake residual deformation.

[0039] This invention forms a rotation fulcrum by connecting the upper flange without gaps, and sets an Ω-shaped damper on the lower flange to concentrate deformation, so that the node has damage control, energy dissipation capacity and self-resetting function.

[0040] All welding of stiffening components to column 1 was completed in the factory. During on-site construction, beam 2 was first hoisted into place, and then cover plate 3 was connected to the upper flange and upper stiffening rib 5 using high-strength bolts. At the same time, the straight connecting section of shape memory alloy Ω-shaped damper 4 was connected to the lower flange and lower stiffening rib 6 respectively. All connections were made using high-strength bolts, avoiding on-site welding and significantly improving construction speed and the controllability of connection quality.

[0041] In this embodiment, washers can be placed under all bolts during the connection process. Their function is to increase the contact area, increase the friction between the bolt and the steel plate, and at the same time play a certain role in energy dissipation and vibration reduction during earthquakes.

[0042] Even if the damper is damaged after a strong earthquake, it can be quickly replaced by simple bolt removal without repairing the main beam and column structure, thus improving the post-earthquake repairability of the structure and reducing the cost and time of post-earthquake repair.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the technical concept and principle of the present invention, or any substantially similar technical means used to achieve substantially similar functions or effects based on the technical solutions disclosed in the present invention, should be covered within the protection scope of the present invention. The protection scope of the present invention is defined by the claims.

Claims

1. A self-resetting beam-column connection node for the weak axis direction of a column, characterized in that, include: Columns, beams, cover plates, and at least one shape memory alloy Ω-shaped damper; The column is provided with upper stiffening ribs and lower stiffening ribs; the end of the beam is connected to the column; there is no gap between the upper flange of the beam and the column, and there is a gap between the lower flange of the beam and the column; The cover plate is used to connect the upper flange of the beam to the upper stiffening rib; The shape memory alloy Ω-shaped damper is disposed between the lower flange of the beam and the lower stiffening rib of the column; the shape memory alloy Ω-shaped damper includes a U-shaped segment and straight connecting segments respectively connected to both ends of the U-shaped segment; the center line of the U-shaped segment is arc-shaped; the straight connecting segments at both ends are respectively fixed to the lower flange of the beam and the lower stiffening rib of the column; the thickness of the U-shaped segment of the shape memory alloy Ω-shaped damper is less than the thickness of its straight connecting segments; the U-shaped segment is disposed in the gap between the lower flange of the beam and the column.

2. The self-resetting beam-column connection node for the weak axis direction of a column according to claim 1, characterized in that, Both the column and the beam are wide-flange cross-section members.

3. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 2, characterized in that, Both the upper stiffening rib and the lower stiffening rib are horizontal through stiffening ribs welded to the column, and are aligned with the upper and lower flanges of the beam, respectively.

4. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 3, characterized in that, The column is also provided with vertical stiffening ribs, which connect the upper stiffening ribs and the lower stiffening ribs.

5. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 4, characterized in that, The shape memory alloy Ω-shaped damper is made of nickel-titanium shape memory alloy.

6. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 5, characterized in that, Multiple shape memory alloy Ω-shaped dampers are provided between the lower flange of the beam and the lower stiffening rib of the column, and are arranged symmetrically with the lower flange of the beam and the web of the beam as axes respectively.

7. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 6, characterized in that, The gap between the lower flange of the beam and the column is equal to the diameter of the U-shaped section of the Ω-shaped damper.

8. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 7, characterized in that, The cover plate is connected to the upper flange of the beam and the upper stiffening rib using high-strength bolts.

9. A self-resetting beam-column connection node for the weak axis direction of a column according to claim 8, characterized in that, The shape memory alloy Ω-shaped damper is connected to the lower flange of the beam and the lower stiffening rib by high-strength bolts.

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