A self-restoring steel-concrete composite column base and frame structure

Abstract

This invention discloses a self-restoring steel-concrete composite column base and frame structure, belonging to the field of civil engineering structural technology. The column base includes a steel-concrete composite column, a support steel plate, a self-resetting device, and a buckling-restrained energy dissipation device. The disc spring of the self-resetting device is placed on the extended anchoring platform of the stiffening angle steel, with a high-strength screw threaded through its center. The upper end of the screw has a rotatable nut for applying the preload of the disc spring, and the lower end of the screw passes through the support steel plate and is anchored to the upper flange of the ground beam. The buckling-restrained energy dissipation device consists of an energy dissipation plate with a weakened middle section and a baffle welded into an L-shape. A filling plate and a cover plate are installed through bolts to the column body to prevent out-of-plane buckling of the buckling restraint steel plate. This column base has the advantages of convenient assembly and disassembly, reasonable stress distribution, stable performance, and the ability to achieve self-resetting after an earthquake and rapid functional recovery.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology in building engineering and structures, specifically to a self-healing steel-concrete composite column base and frame structure. Background Technology

[0002] "Recoverable functional structures" have become a new paradigm for seismic design due to their advantage of rapidly restoring building functionality after a strong earthquake. These structures encompass structures with replaceable components, swaying structures, and self-resetting structures, among which self-resetting structures are particularly favored for their reduced ductility design requirements and earthquake damage reduction.

[0003] In the design system of self-setting structures, the main research directions include frame structures, connection nodes, energy dissipation elements, and prestressing technology. However, research on self-setting column bases urgently needs to be deepened because even if the beam-column joint, as the primary seismic defense line, develops a plastic hinge, the first-floor column base may still develop a plastic hinge during subsequent vibrations. Irreversible damage to the column base area exacerbates residual deformation of the structure, severely weakens seismic performance and self-setting capability, and hinders post-earthquake functional recovery.

[0004] Currently, although column bases are rationally designed to concentrate plastic damage on replaceable energy-dissipating components, thereby achieving a self-resetting effect while protecting the main structure, each design still has certain shortcomings. For example, self-resetting reinforced concrete column bases are prone to concrete spalling and peeling; self-resetting steel column bases are prone to outer flange buckling when rotating along the weak axis; regarding the self-resetting mechanism, prestressed tendon self-resetting components suffer from problems such as easy yielding, poor deformation capacity, and easy loss of prestress; at the same time, there are also problems such as difficulty in replacing metal yielding energy-dissipating devices and insufficient buckling restraint. Summary of the Invention

[0005] This invention provides a self-restoring steel tube concrete column base and frame structure, which solves the problems of weak self-restoring ability and energy dissipation capacity of existing column bases, easy yielding and poor deformation capacity of self-restoring elements and easy loss of prestress, as well as the difficulty in replacing metal yielding energy dissipation devices and insufficient buckling restraint.

[0006] This invention is achieved through the following technical solution:

[0007] A self-restoring steel-concrete composite column base includes a steel-concrete composite column, a support plate, a self-resetting device, and a buckling-resistant energy dissipation device.

[0008] The self-resetting device includes an elastic device and a support component; the steel pipe concrete column is set on the top of the support steel plate, the support component is set on the side wall of the steel pipe concrete column, the elastic device is set on the support component, the upper end of the elastic device is connected to one end of the fastening device, and the other end of the fastening device is used to connect to the ground beam and put the elastic device in a pre-compression state.

[0009] The buckling-restrained energy dissipation device includes a buckling-restrained energy dissipation plate and a fixing device. The buckling-restrained energy dissipation plate is pressed against the side wall of the steel-concrete composite column by the fixing device, and the lower end of the buckling-restrained energy dissipation plate is fixedly connected to the support steel plate. A cover plate is provided on the side of the buckling-restrained energy dissipation plate away from the steel-concrete composite column to limit the out-of-plane buckling of the buckling-restrained energy dissipation plate.

[0010] Preferably, the elastic device is connected to the ground beam via a screw assembly, the screw assembly including a screw and a nut;

[0011] The upper end of the screw is connected to the upper end of the elastic device, and the lower end of the screw passes through the support component and the support steel plate in sequence and is fixed to the ground beam. The nut is connected to the upper end of the screw and is used to fix the elastic device and adjust the preload.

[0012] Preferably, the elastic device is a helical spring, a disc spring, or high-elasticity rubber.

[0013] Preferably, the support component includes an anchor seat, the top surface of which is an anchoring platform for installing an elastic device. An upwardly extending fixing plate is provided on the side of the anchoring platform near the steel-concrete composite column. Parallel stiffening plates are provided on both sides of the bottom of the anchoring platform, and one end of the stiffening plate is used to abut against the side wall of the steel-concrete composite column.

[0014] Preferably, the buckling-resistance energy dissipation plate has symmetrically arranged energy-weakening sections on both sides, so that the buckling-resistance energy dissipation plate forms fixed-point energy dissipation.

[0015] Preferably, the energy-dissipating section is a groove provided on the side wall of the buckling-resistant energy-dissipating plate.

[0016] Preferably, the buckling-resistance energy dissipation plate includes an energy dissipation plate and a connecting plate. The energy dissipation plate is fixed to the side wall of the steel-concrete composite column and located at the bottom of the elastic device. The connecting plate is horizontally fixed to the bottom of the energy dissipation plate and is connected to the support steel plate.

[0017] Preferably, a filler plate is provided between the buckling-restrained energy-dissipating plate and the side wall of the steel-concrete composite column, and a cover plate is pressed onto the surface of the buckling-restrained energy-dissipating plate by multiple bolts and connected to the steel-concrete composite column.

[0018] Preferably, the surface of the cover plate is provided with stiffening ribs.

[0019] A frame structure, wherein the column base nodes of the frame structure are provided with the aforementioned self-healing steel-concrete composite column base.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This application provides a self-restoring steel-concrete composite column base, employing a pre-compressed self-resetting device to provide a reset function, and a buckling-restrained energy dissipation device to realize the principle of metal yielding energy dissipation. The symmetrical arrangement of the self-resetting and buckling-restrained energy dissipation devices gives the column base excellent seismic resistance and self-resetting performance. During operation, the self-resetting and buckling-restrained energy dissipation devices are separated, and the reset function and energy dissipation capacity show a positive correlation, resulting in strong load-bearing capacity and outstanding energy dissipation and self-resetting capabilities. This column base is easy to assemble and disassemble, has a reasonable stress distribution, and stable performance, enabling self-resetting and rapid functional recovery after an earthquake. Furthermore, during the column base's operation, column rotation causes compression of the buckling-restrained energy dissipation plate on the near-rotation side and tensile deformation of the buckling-restrained energy dissipation plate on the far side, thus providing the column base with resistance to bending moment. Simultaneously, the far-side elastic device undergoes compressive deformation, providing elastic restoring force to the column base. When the resistance to bending moment provided by the elastic restoring force of the elastic device and the axial pressure is greater than the resistance to bending moment provided by the buckling-restrained energy dissipation plate, the column base is considered to have achieved self-resetting. Secondly, the column base is selected with different axial compression ratios, different initial preload of elastic devices, and different bending contribution ratios to meet the adjustability requirements of actual engineering projects. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a self-healing steel-concrete composite column base according to the present invention;

[0024] Figure 2 This is an exploded view of a self-healing steel-concrete composite column base according to the present invention.

[0025] Figure 3 This is a schematic diagram of the buckling-resistant energy-dissipating plate of the present invention;

[0026] Figure 4 This invention provides a load-displacement curve for a self-restoring steel-concrete composite column base.

[0027] Figure 5 This is a simplified force diagram of a self-restoring steel-concrete composite column base according to the present invention.

[0028] Figure 6 This is the load-displacement curve of the column base specimen CB-1 of this invention;

[0029] Figure 7 This is the load-displacement curve of the column base specimen CB-2 of this invention;

[0030] Figure 8 This is the load-displacement curve of the column base specimen CB-3 of this invention;

[0031] Figure 9 This is the load-displacement curve of the column base specimen CB-4 of this invention;

[0032] Figure 10 This is the load-displacement curve of the column base specimen CB-5 of this invention;

[0033] Figure 11 Comparison of skeleton curves from tests on column base specimens CB-1 to CB-5 of this invention;

[0034] Figure 12 Comparison of residual deformation in tests of column base specimens CB-1 to CB-5 of this invention;

[0035] Figure 13 This is a comparison of the energy dissipation capacity of the column base specimens CB-1 to CB-5 of this invention.

[0036] Figure 14 This invention provides a comparison of the experimental and theoretical load-displacement curves for the column base specimens CB-1 to CB-5.

[0037] In the diagram: 1. Disc spring; 2. Anchor seat; 3. High-strength bolt; 4. Filler plate; 5. Buckling-resistant energy-dissipating plate; 6. Cover plate; 7. High-strength bolt; 8. Support steel plate; 9. Ground beam; 10. Steel-concrete composite column. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0040] A self-restoring steel-concrete composite column base includes a steel-concrete composite column 10, a support steel plate 8, a self-resetting device, and a buckling-resistant energy dissipation device.

[0041] The self-resetting device includes an elastic device and a support component; the steel pipe concrete column 10 is set on the top of the support steel plate 8, the support component is set on the side wall of the steel pipe concrete column 10, the elastic device is set on the support component, the elastic device is connected to one end of the fastening device, and the other end of the fastening device is used to connect to the ground beam 9 and to put the elastic device in a pre-compression state.

[0042] The buckling-restrained energy dissipation device includes a buckling-restrained energy dissipation plate 5 and a fixing device. The buckling-restrained energy dissipation plate 5 is pressed against the side wall of the steel-concrete composite column 10 by the fixing device, and the lower end of the buckling-restrained energy dissipation plate 5 is fixedly connected to the support steel plate 8. A cover plate is provided on the side of the buckling-restrained energy dissipation plate 5 away from the steel-concrete composite column 10 to limit the out-of-plane buckling of the buckling-restrained energy dissipation plate 5.

[0043] Under frequent earthquakes, the column base of this steel-concrete composite column exhibits no relative rotational deformation with respect to the foundation, demonstrating a rigid connection. In this case, the buckling-resistance energy dissipation plate remains elastic, ensuring building comfort. Under design earthquakes and rare earthquakes, the column base is allowed to rotate relative to the foundation, exhibiting semi-rigid connection characteristics. The column base achieves self-reset after the earthquake thanks to the plastic energy dissipation of the buckling-resistance energy dissipation plate, the self-resetting disc spring device, and the restoring force provided by axial compression. Furthermore, under strong earthquakes, if the disc spring is compressed to its limit state, the rotational stiffness of the column base increases dramatically, transforming it into a traditional rigid column base. Ultimately, crushing failure will occur near the rotation point at the column base. Therefore, the typical expected failure characteristics of this column base are: buckling-resistance energy dissipation plate enters a plastic state → disc spring self-resetting device limits → (self-reset) → crushing failure near the rotation edge at the column base. This column base provides restoring force through pre-compressed disc springs and axial compression. The buckling-resistance energy dissipation plate achieves targeted energy dissipation and concentrated damage. After an earthquake, only the energy dissipation device needs to be replaced to quickly restore the normal function of the column base.

[0044] In some embodiments, the elastic device is connected to the ground beam 9 via a screw assembly, the upper end of the screw assembly is connected to the upper end of the elastic device, and the lower end of the screw assembly passes through the support member and the support steel plate 8 in sequence and is fixed to the ground beam 9.

[0045] Optionally, the screw assembly includes a high-strength screw 3 and a nut. The lower end of the high-strength screw 3 is welded and fixed to the ground beam, and the nut is set at the upper end of the high-strength screw. The preload of the elastic device can be adjusted by rotating the nut.

[0046] Optionally, elastic devices are provided on both sides of the steel-concrete composite column 10, with at least one elastic device on each side. Several elastic devices are spaced apart along the sidewalls of the steel-concrete composite column 10, and each elastic device is connected to the ground beam through a high-strength bolt.

[0047] Optionally, multiple elastic devices can be set on the same support component, or each elastic device can be set on a corresponding support component. Preferably, multiple elastic devices can be set on one support component, which can reduce the cost of the column base and facilitate the installation and disassembly of the elastic devices.

[0048] Optionally, each sidewall of the steel-concrete composite column 10 is provided with a self-resetting device.

[0049] Optionally, the elastic device is a helical spring, a disc spring 1, or a high-elasticity rubber.

[0050] In some embodiments, the supporting component is an anchoring seat 2, the top surface of the anchoring seat 2 is an anchoring platform for installing an elastic device, and an upwardly extending fixing plate is provided on the side of the anchoring platform near the steel-concrete composite column 10. The fixing plate is fixed to the steel-concrete composite column 10 by bolts. Parallel stiffening plates are provided on both sides of the bottom of the anchoring platform, and one end of the stiffening plate is used to abut against the side wall of the steel-concrete composite column 10.

[0051] For example, the upper end of the high-strength screw 3 passes through the disc spring 1 and the stiffening angle steel 2, and the lower end of the high-strength screw 3 passes through the support steel plate 8 and the upper flange of the ground beam 9. The two ends are preloaded by rotatable nuts. The two ends of the high-strength screw 3 are connected by nuts to preload the initial preload of the disc spring self-resetting device.

[0052] In some embodiments, the buckling-resistance energy dissipation plate 5 is provided with a weakening energy dissipation section in the middle, so that the buckling-resistance energy dissipation plate 5 forms a fixed-point energy dissipation.

[0053] A weakened energy dissipation section is set in the middle of the buckling-restrained energy dissipation plate 5. This design makes the weakened energy dissipation section a "weak point" in the structure when subjected to external forces, making it more prone to deformation. Due to the presence of the weakened energy dissipation section, when the structure is subjected to external forces such as earthquakes and wind loads, these forces will be concentrated on the weakened energy dissipation section, making it the main area for energy absorption and dissipation.

[0054] When external forces act on a concrete-filled steel tube column, the buckling-restrained energy-dissipating plate 5 absorbs and dissipates this energy through its weakening energy-dissipating section. The deformation of the weakening energy-dissipating section absorbs a large amount of energy and converts it into heat energy through plastic deformation of the material, friction, and other means, thereby reducing the impact on the main structure (such as the concrete-filled steel tube column).

[0055] Through its fixed-point energy dissipation design, the buckling-restrained energy dissipation plate 5 can effectively protect the main structure, such as the steel-concrete composite column, from or reduce damage from external forces. In the event of disasters such as earthquakes, the weakened energy dissipation section of the buckling-restrained energy dissipation plate 5 will deform and dissipate energy first, thereby reducing the stress on the main structure and improving its seismic performance.

[0056] The main reasons for setting the weakening section in the energy dissipation plate are as follows: 1) Fixed-point energy dissipation: The weakening section causes the energy dissipation plate to undergo plastic deformation in a local area first under seismic action, thus concentrating the energy dissipation of the seismic energy and avoiding premature failure of the entire buckling-resistance energy dissipation plate 5 or adjacent structural components.

[0057] 2) Damage controllable: By “directional design” of the weakening section, plastic deformation under seismic action can be limited to a preset area, reducing damage to other key components (such as steel-concrete composite columns and disc springs);

[0058] 3) Facilitates post-earthquake replacement of energy-dissipating panels, enabling rapid structural recovery. From the perspectives of seismic performance, damage control, and maintainability, the inclusion of weakening sections is essential. It ensures efficient energy dissipation by the buckling-resistance energy-dissipating panels, limits the extent of damage, and simplifies subsequent repair procedures.

[0059] Optionally, the weakening energy dissipation section is symmetrically arranged in both directions at the middle of the buckling-resistance energy dissipation plate along its length. The weakening energy dissipation section is a groove provided on the side wall of the buckling-resistance energy dissipation plate. Preferably, grooves are provided on both sides of the buckling-resistance energy dissipation plate to balance the force on the weakening energy dissipation section.

[0060] Optionally, the buckling-resistance energy-dissipating plate includes an energy-dissipating plate and a connecting plate, and has an L-shaped structure. The energy-dissipating plate is fixed to the side wall of the steel-concrete composite column 10 by multiple bolts and is located at the bottom of the elastic device. The connecting plate is horizontally arranged at the bottom of the energy-dissipating plate. One end of the connecting plate is connected to the lower end of the energy-dissipating plate, and the other end extends away from the steel-concrete composite column 10. The connecting plate is located at the bottom of the support steel plate and is connected by multiple bolts.

[0061] Optionally, a filler plate 4 is provided between the buckling-restrained energy-dissipating plate and the side wall of the steel-concrete composite column 10 to form a tight contact between the buckling-restrained energy-dissipating plate and the steel-concrete composite column 10. The cover plate 6 is pressed onto the surface of the buckling-restrained energy-dissipating plate by multiple bolts, and the bolts are connected to the steel-concrete composite column 10.

[0062] The cover plate is equipped with stiffening ribs to further prevent out-of-plane buckling. The filler plate is a perforated square steel plate. The upper and lower ends of the filler plate, the upper end of the buckling-resistance energy dissipation plate, and the upper and lower ends of the cover plate are fixed to the column perimeter by through high-strength bolts. The lower end baffle of the buckling-resistance energy dissipation plate is fixed to the support steel plate by friction-type high-strength bolts. The support steel plate is fixed to the flange plate of the ground beam.

[0063] Optionally, when buckling-resistance energy dissipation devices are provided on both symmetrical sides of the steel-concrete composite column 10, bolts pass through the steel-concrete composite column 10, and the two ends of the bolts are respectively connected to two buckling-resistance energy dissipation devices.

[0064] Example 1

[0065] A self-healing steel-concrete composite column base, wherein the steel-concrete composite column 10 has a height of 2.4m, a cross-sectional dimension of 300×300mm, and a steel pipe wall thickness of 10mm.

[0066] The steel-concrete composite column 10 is filled with C40 concrete and the external steel is Q355 steel.

[0067] Disc spring 1 is composed of 16 disc springs combined together, and its stiffness is 5.89kN / mm.

[0068] The disc spring is made of 60Si2MnA alloy steel with a yield stress of 1400MPa, an outer diameter of 80mm, an inner diameter of 37.2mm, a thickness of 8mm, a free height of 10.5mm, and a stiffness of 94.27kN / mm.

[0069] The disc spring 1 extends outward from the anchoring platform of the anchoring seat 2, and an 8.8 grade M36 high-strength screw 3 passes through its center. The upper end of the screw has a rotatable nut, and the lower end passes through the support steel plate 8 and is anchored to the lower surface of the upper flange of the ground beam 9.

[0070] The stiffening angle steel 8 is connected to the column by a through-hole connection using 10.9 grade M24×400mm high-strength bolts 7.

[0071] The upper part of the buckling-resistant energy dissipation device is connected to the column through a 12.9 grade M27×450mm high-strength bolt, the middle part is connected to the column through a 10.9 grade M24×450mm high-strength bolt, and the lower part is connected to the ground beam through a 10.9 grade M24×120mm high-strength bolt.

[0072] Example 2

[0073] A frame structure, wherein the column base nodes of the frame structure are provided with the aforementioned self-healing steel-concrete composite column base.

[0074] The frame structure includes a ground beam and columns, with the columns vertically mounted on the ground beam. The nodes between the ground beam and the columns are fitted with the self-healing steel-concrete composite column bases.

[0075] The following is in conjunction with the appendix Figure 4-5 This embodiment provides a detailed description of the load-displacement curve and stress mechanism of a self-restoring steel-concrete composite column base:

[0076] Figure 4 This is a load-displacement curve for a self-restoring steel-concrete composite column base in Embodiment 1. In the figure, P This refers to the horizontal load at the top of the column; δThis represents the horizontal displacement at the column top. During operation, considering the elastic bending deformation of the column before rotation, the load-displacement curve at the column base is divided into six stages. Stage 0-1 represents the initial stiffness of the column base, provided by the elastic deformation of the concrete-filled steel tube column itself. When loaded to point 1, the bending moment at the column base equals the bending moment provided by the initial preload of the disc spring and the axial compression, indicating that the column is about to rotate. As the horizontal load increases, the lateral stiffness of the column base in stage 1-2... Lateral stiffness provided for disc springs Lateral stiffness provided by axial compression Lateral stiffness provided by the elastic stage of the buckling-resistance energy dissipation plate The sum. When loaded to point 2, the buckling-restrained energy-dissipating plate on the side away from the rotation center yields in tension and begins plastic deformation. The lateral stiffness of the column base in stages 2-3. Lateral stiffness provided for disc springs Lateral stiffness provided by axial compression Lateral stiffness provided by the buckling-restrained energy dissipation plate during the plastic stage The sum of the values. When the column reaches the target lateral displacement point 3, the horizontal displacement load is at its maximum. Stages 3-4 are the elastic bending deformation recovery stage of the column before the column base is unloaded and rotated; the stiffness in this stage is the same as the initial stiffness. In stages 4-5, the buckling-restrained energy-dissipating plate on the side away from the rotation center undergoes tensile deformation during loading. During this unloading stage, the buckling-restrained energy-dissipating plate undergoes compressive deformation. When unloading reaches point 5, the buckling-restrained energy-dissipating plate begins to yield under compressive stress. Unloading continues to point 6, the relative rotation angle between the column and the support base plate is zero, and the column base completes its self-reset.

[0077] Figure 5 (a) is a simplified force diagram when the column base is not rotated. At this time, the buckling-restrained energy dissipation plate has not yet undergone axial deformation, and the force exerted on the column base is zero. In the figure, For axial loads on steel-concrete composite columns, This is the initial preload of the disc spring. The distance from the horizontal lateral displacement loading point to the top surface of the foundation is [the distance from the loading point to the top surface of the foundation]. The distance from the plane of the stiffening angle steel bearing cap to the surface of the foundation. The width of the column cross section. The distance from the central axis of the self-resetting device to the side of the steel-concrete composite column. Let the center of rotation be the column base. Then the separate load of this column base... for:

[0078]

[0079] When the horizontal displacement load exceeds the separation load, the column base begins to rotate; the stress state is shown in the diagram. Figure 5 (b). In the figure, , These are the reaction forces of the BRS-T and BRS-C plates on the column base, respectively (the resisting bending moment generated by the BRS-C plate is negligible). For the corner of the column base, , These represent the pressure inside the disc springs on the side furthest from the rotation center and the side closest to the rotation center, respectively.

[0080] The following is a derivation of the formula for calculating the lateral stiffness during rotation in this invention:

[0081] 1) Axial stiffness of a single disc spring for:

[0082]

[0083] in: ,

[0084] In the formula: , , , These are the axial stiffness, number of stacks, number of mating groups, and axial stiffness of a single disc spring, respectively. , , , These are the axial stiffness, elastic modulus, cross-sectional area, and length of the central shaft of the disc spring.

[0085] By the principle of virtual work, assuming a unit rotation angle of 1 at the column base, the lateral displacement of the column top is H. When only the effect of the disc spring is considered, the equation is:

[0086]

[0087] The lateral stiffness provided by the disc spring for:

[0088]

[0089] 2) Lateral stiffness provided by buckling-restrained energy dissipation plates

[0090] Elastic axial stiffness of buckling-restrained energy dissipation plate With plastic axial stiffness They are respectively:

[0091]

[0092]

[0093] In the formula: , , These are the length of the energy-dissipating section of the buckling-resistant energy-dissipating plate, the cross-sectional area of ​​the energy-dissipating section, and the elastic modulus, respectively.

[0094] Similarly, the lateral stiffness provided by the buckling-resistance energy dissipation plate can be obtained from the principle of virtual work. for:

[0095]

[0096] 3) Lateral stiffness provided by axial compression

[0097] The lateral stiffness provided by axial compression can be obtained from the principle of virtual work. for:

[0098]

[0099] 4) Total lateral stiffness of the self-resetting column base

[0100] For the overall analysis of the self-resetting column base with preloaded disc springs, its total lateral stiffness is the sum of the lateral stiffness provided by the disc springs, the buckling-restrained energy-dissipating plate, and the axial compressive strength of the column, that is:

[0101]

[0102] The following is a derivation of the formulas for calculating the bending moment at each characteristic point during the rotation process of this invention. , For feature points i The corresponding bending moment and rotation angle:

[0103] When the column base is about to rotate under horizontal load, its initial resistance moment Equal to the separation moment, that is:

[0104]

[0105] The resisting bending moment after column base separation is provided by axial compression, the tension of disc springs, and the axial force of buckling-restrained energy-dissipating plates. The bending moment expressions for characteristic points 2 to 6 are as follows:

[0106]

[0107] In the formula: The axial force of the buckling-resistance energy dissipation plate at the column base rotation angle is respectively The resisting bending moment provided by the buckling-resistance energy dissipation plate. Therefore, the bending moments at characteristic points 2 to 6 are provided by the axial force of the buckling-resistance energy dissipation plate. for:

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] In the formula: , These represent the compressive forces acting on the BRS-T plate during tensile and compressive yielding, respectively. The above calculations are based on the infinitesimal theory of mathematical calculus, neglecting the influence of higher-order infinitesimals.

[0114] To achieve self-resetting of the column base, i.e., zero residual displacement of the column base, it should be made that... ,Right now:

[0115]

[0116] Bending moment values ​​at column bases at each characteristic point Horizontal load at column top The following relationship exists:

[0117]

[0118] Furthermore, since only the elastic lateral displacement of the concrete-filled steel tube column before loading and unloading rotation is considered, the lateral displacement of the column top at each characteristic point can be obtained. Calculation formula:

[0119]

[0120] In the formula: The combined flexural stiffness of the steel-concrete composite column.

[0121] By combining equations (2-19), the characteristic value of the load-displacement curve of the column base throughout the entire process can be obtained.

[0122] The following is in conjunction with the appendix Figure 6-14 The performance of this embodiment will be further explained as follows:

[0123] Figure 6-10The load-displacement curves of five column base specimens with different axial compression ratios, initial preload of disc springs, and bending contribution ratios, as shown in Table 1, are as follows: Except for specimens CB-1 and CB-2, whose hysteresis curves exhibit an "arch" shape, the hysteresis curves of CB-3 to CB-5 all show a full "double flag" shape, indicating stable energy dissipation capacity, gradually decreasing residual displacement, and increasingly better self-resetting ability. Initially, the horizontal displacement load is small, and the energy dissipation section of the buckling-resistance plate is still in an elastic state, without plastic energy dissipation. Therefore, the area enclosed by the hysteresis loop is small, resulting in insufficient energy dissipation capacity. As the horizontal displacement load increases, the strain of the buckling-resistance plate increases, exceeding the elastic range and beginning to yield and dissipate energy. Therefore, the area enclosed by the hysteresis curve gradually increases, and the energy dissipation capacity of the column base gradually improves. Meanwhile, the hysteresis curves of specimens CB-1 and CB-2 show significant differences in the degree of squeezing and overall shape compared to those of specimens CB-3 to CB-5; however, the load-displacement curves of specimens CB-3 to CB-5 are quite similar in terms of the degree of squeezing and overall shape. This indicates from a macroscopic perspective that the axial compression ratio has a stronger impact on the seismic performance of the column base than the initial preload of the disc spring.

[0124] Table 1 Specimen Parameters

[0125]

[0126] Figure 11 A comparison of the skeleton curves of the column base specimens CB-1 to CB-5 of this invention shows that the overall trend of the skeleton curves of each specimen is basically consistent. In the early stage of loading, the column base did not lift, and the lateral displacement of the column top was generated by the elastic bending deformation of the column body. Therefore, the initial stiffness of each specimen was relatively large, and it was in a linear state. Increasing the axial compression ratio of the column and the initial preload of the disc spring can improve the separation load and yield load of the column base. Moreover, the influence of the axial compression ratio on the separation load and yield load of the column base is more significant than that of the disc spring preload. In addition, when the horizontal load at the top of the column exceeds the separation load, the column base rotates, and the energy dissipation section of the buckling-restrained energy dissipation plate gradually transitions from an elastic state to a plastic state, resulting in a gradual decrease in the stiffness of the column base, showing its good ductility. By increasing the axial compression ratio of the column and the initial preload of the disc spring, the overall stiffness of the column base can be effectively improved, thereby enhancing its load-bearing stability. Increasing both the axial compression ratio of the column and the initial preload of the disc springs can improve the load-bearing capacity of the column base, with increasing the initial preload of the disc springs being more effective than increasing the axial compression ratio of the column. This is because when the column base rotates, the change in stiffness of the column base is jointly determined by the buckling-restrained energy-dissipating plate and the disc springs; in the later stages of loading, when the entire cross-section of the buckling-restrained energy-dissipating plate yields, the contribution of the buckling-restrained energy-dissipating plate to the stiffness of the column base no longer increases, and at this point, the change in the stiffness of the column base depends on the stiffness of the disc springs; while increasing the initial preload of the disc springs increases both the vertical load on the column base and the stiffness of the disc springs.

[0127] Figure 12For the comparison of residual deformation of column base specimens CB-1 to CB-5 of this invention, when the inter-story drift angle reaches 2.00%, except for specimens CB-1 and CB-2 whose residual deformation is greater than 0.2%, the other specimens all meet the self-resetting performance requirements and have good self-resetting ability. When the inter-story drift angle reaches 3.00%, the residual deformation of the specimens are 2.06%, 0.61%, 0.31%, 0.21%, and 0.19%, respectively. Among them, the residual deformation of specimens CB-4 and CB-5 is still close to 0.2%, indicating that the specimens can still maintain a small residual deformation under strong earthquake, which helps the column base to quickly recover its function after the earthquake. At the same time, the residual deformation of specimens CB-2 and CB-3 is reduced by 70.61% and 84.80% respectively compared with CB-1, while the residual deformation of specimens CB-4 and CB-5 is reduced by 32.89% and 39.80% respectively compared with CB-3. This shows that within a certain range, increasing the axial compression ratio of the column and the initial preload of the disc spring can improve its self-resetting ability, and increasing the axial compression ratio of the column has a more significant effect on improving the self-resetting ability than increasing the initial preload of the disc spring.

[0128] Figure 13 For the comparison of energy dissipation capacity of column base specimens CB-1 to CB-5 of this invention, when the horizontal displacement load is small, the buckling-resistance energy dissipation plate is in an elastic state, and therefore the energy dissipation capacity is low. As the load increases, the buckling-resistance energy dissipation plate enters the yielding energy dissipation stage, and the energy dissipation capacity of each specimen gradually increases and remains at a high level. When the horizontal displacement load reaches 60 mm (3.00% displacement angle), the energy dissipation of specimens CB-2 and CB-3 is reduced by 4.28% and 12.28% compared with specimen CB-1, respectively; the energy dissipation of specimens CB-4 and CB-5 is reduced by 3.20% and 6.83% compared with specimen CB-3, respectively. Therefore, increasing the axial compression ratio and the initial preload of the disc spring will reduce the energy dissipation capacity and the equivalent viscous damping coefficient of the column base, and increasing the axial compression ratio has a more significant effect on the energy dissipation capacity and the equivalent viscous damping coefficient.

[0129] Figure 14 To compare the experimental and theoretical load-displacement curves of the column base specimens CB-1 to CB-5 of this invention, the corresponding horizontal loads of specimens CB1 to CB5 were calculated based on the calculation formula of the column base load-displacement curve. The experimental and theoretical results were compared, showing good fit between the experimental and theoretical results, with calculation errors all within 15%. The calculation error is relatively large, which causes the stiffness of the restoring force theoretical model to be slightly greater than the experimental value in the early stage of unloading. The reasons are: first, there are small gaps between the fixing bolts and the hole wall of the buckling-restrained energy dissipation plate in the actual test, resulting in insufficient contact in the early stage of unloading, which causes a slight reduction in the stiffness of the column base in a local area; second, during the operation of the buckling-restrained energy dissipation device, there is mutual friction between the buckling-restrained energy dissipation plate and the cover plates and filling plates on both sides.

[0130] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A self-centering steel tube concrete column base, characterized by, The self-resetting device comprises an elastic device and a supporting part; the steel pipe concrete column is arranged on the top of the supporting steel plate, the supporting part is arranged on the side wall of the steel pipe concrete column, the elastic device is arranged on the supporting part, the upper end of the elastic device is connected with one end of the fastening device, the other end of the fastening device is used for connecting the ground beam, and the elastic device is in a pre-pressing state. The anti-buckling energy dissipation device comprises an anti-buckling energy dissipation plate and a fixing device, the anti-buckling energy dissipation plate is pressed and pasted on the side wall of the steel pipe concrete column through the fixing device, the lower end of the anti-buckling energy dissipation plate is fixedly connected with the supporting steel plate, a cover plate is arranged on the side of the anti-buckling energy dissipation plate away from the steel pipe concrete column, and the cover plate is used for limiting the out-of-plane buckling of the anti-buckling energy dissipation plate. The anti-buckling energy dissipation plate is provided with weakened energy dissipation sections on two sides in a symmetrical mode, so that the anti-buckling energy dissipation plate forms fixed-point energy dissipation. The anti-buckling energy dissipation plate and the side wall of the steel pipe concrete column are provided with a filling plate, and the cover plate is press-connected on the surface of the anti-buckling energy dissipation plate through a plurality of bolts and is connected with the steel pipe concrete column. The elastic device is connected with the ground beam through a screw rod assembly, and the screw rod assembly comprises a screw rod and a nut.

2. A self-centering steel tube concrete column base according to claim 1, characterized in that, The upper end of the screw rod is connected with the upper end of the elastic device, the lower end of the screw rod is sequentially connected with the ground beam through the supporting part and the supporting steel plate, the nut is connected with the upper end of the screw rod, and the nut is used for fixing the elastic device and adjusting the pre-pressing force. The elastic device is a spiral spring, a disc spring or high-elastic rubber.

3. The self-centering steel tube concrete column base according to claim 1, characterized in that, The supporting part comprises an anchoring seat, the top surface of the anchoring seat is an anchoring platform used for mounting the elastic device, the side of the anchoring platform close to the steel pipe concrete column is provided with an upwardly extending fixing plate, the bottom of the anchoring platform is provided with parallel stiffening plates on two sides, and one end of the stiffening plates is used for abutting against the side wall of the steel pipe concrete column.

4. The self-centering steel tube concrete column base according to claim 1, characterized in that, The weakened energy dissipation section is a groove arranged on the side wall of the anti-buckling energy dissipation plate.

5. The self-centering steel tube concrete column base according to claim 1, wherein, The anti-buckling energy dissipation plate comprises an energy dissipation plate and a connecting plate, the energy dissipation plate is fixed on the side wall of the steel pipe concrete column and is located at the bottom of the elastic device, and the connecting plate is horizontally fixed on the bottom of the energy dissipation plate and is connected with the supporting steel plate.

6. The self-centering steel tube concrete column base according to claim 1, wherein, The surface of the cover plate is provided with stiffening ribs.

7. The self-centering steel tube concrete column base according to claim 1, wherein, The column foot node of the frame structure is provided with the self-resetting steel pipe concrete column foot of any one of claims 1-7.

8. A frame structure, characterized by, ​

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