Self-recovery steel pipe concrete column base and frame structure

Abstract

The invention discloses a self-recovery concrete-filled steel tube column base and a frame structure, and belongs to the technical field of civil engineering structures. The column base comprises a concrete-filled steel tube column, a support steel plate, a self-resetting device and a buckling-restrained energy consumption device; a belleville spring of the self-resetting device is arranged on a stiffening angle steel extending anchoring platform, a high-strength screw penetrates through the center of the belleville spring, a rotatable nut is arranged at the upper end of the screw and used for applying pre-pressure of the belleville spring, and the lower end of the screw penetrates through a support steel plate and is anchored to a ground beam upper flange. An anti-buckling energy consumption plate of the anti-buckling energy consumption device is formed by welding an energy consumption plate with the middle weakened and a baffle into an L shape, and a filling plate and a cover plate are connected and arranged through column body opposite penetrating bolts so as to prevent the buckling restrained steel plate from buckling out of the plane. The column base has the advantages of being convenient to disassemble and assemble, reasonable in stress, stable in performance, capable of achieving automatic reset after an earthquake and rapid recovery of functions and the like.

Description

Technical Field

[0001] The invention relates to the technical field of building engineering and structural vibration control, and in particular to a self-recovering steel tube concrete column foot and frame structure. Background Art

[0002] "Recoverable functional structures" have become a new paradigm for earthquake-resistant design due to their advantage of quickly restoring building functions after a strong earthquake. This structure includes structures with replaceable components, swing structures, and self-resetting structures. Among them, self-resetting structures are highly favored for their characteristics of reducing ductility design requirements and reducing earthquake damage.

[0003] In the self-resetting structure design system, the main research directions include frame structure, connection nodes, energy-absorbing elements and prestressing technology. However, the current research on self-resetting column foot needs to be deepened. The reason is that even if the beam-column node as the primary seismic defense line has a plastic hinge, the first-floor column foot may still have a plastic hinge in subsequent vibrations. The irreversible damage in the column foot area aggravates the residual deformation of the structure, seriously weakens the seismic performance and self-resetting ability, and hinders the recovery of post-earthquake functions.

[0004] At present, although the column base has been reasonably designed to concentrate the plastic damage on the replaceable energy-absorbing elements, thus achieving the self-resetting effect while protecting the main structure, there are still certain shortcomings. For example, the self-resetting reinforced concrete column base is prone to concrete fragmentation and peeling; the self-resetting steel column base is prone to outer flange buckling when rotating along the weak axis; in terms of the self-resetting mechanism, the prestressed tendon self-resetting elements have 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 yield-type energy-absorbing devices and insufficient anti-buckling constraints. Summary of the invention

[0005] The present invention provides a self-recovering steel tube concrete column base and frame structure, which solves the problems of weak self-resetting ability and energy dissipation capacity of the existing column base, easy yielding and poor deformation capacity of the self-resetting element and easy loss of prestress, difficulty in replacing the metal yield type energy dissipation device and insufficient anti-buckling constraint.

[0006] The present invention is achieved through the following technical solutions: A self-recovering steel tube concrete column foot, comprising a steel tube concrete column, a support steel plate, a self-resetting device and an anti-buckling energy dissipation device; The self-resetting device includes an elastic device and a supporting component; the steel tube concrete column is arranged on the top of the support steel plate, the supporting component is arranged on the side wall of the steel tube concrete column, the elastic device is arranged on the supporting 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 the ground beam, and the elastic device is in a pre-stressed state; The anti-buckling energy dissipation device includes an anti-buckling energy dissipation plate and a fixing device. The anti-buckling energy dissipation plate is pressed against the side wall of the steel tube concrete column through the fixing device, and the lower end of the anti-buckling energy dissipation plate is fixedly connected to the support steel plate. A cover plate is arranged on the side of the anti-buckling energy dissipation plate away from the steel tube concrete column to limit the out-of-plane buckling of the anti-buckling energy dissipation plate.

[0007] Preferably, the elastic device is connected to the ground beam via a screw assembly, and the screw assembly includes a screw and a nut; The upper end of the screw is connected to the upper end of the elastic device, the lower end of the screw passes through the supporting component and the bearing steel plate in sequence and is fixed to the ground beam, and the nut is connected to the upper end of the screw for fixing the elastic device and adjusting the preload.

[0008] Preferably, the elastic device is a coil spring, a disc spring, or a highly elastic rubber.

[0009] Preferably, the supporting component includes an anchor seat, the top surface of the anchor seat is an anchor platform for installing the elastic device, an upwardly extending fixing plate is provided on the side of the anchor platform close to the steel tube concrete column, and mutually parallel stiffening plates are provided on both sides of the bottom of the anchor platform, and one end of the stiffening plate is used to abut against the side wall of the steel tube concrete column.

[0010] Preferably, the energy-weakening sections are symmetrically arranged on both sides of the anti-buckling energy-dissipating plate, so that the anti-buckling energy-dissipating plate forms fixed-point energy dissipation.

[0011] Preferably, the energy-dissipating weakened section is a groove provided on the side wall of the anti-buckling energy-dissipating plate.

[0012] Preferably, the anti-buckling energy absorption plate includes an energy absorption plate and a connecting plate. The energy absorption plate is fixed on the side wall of the steel tube concrete column and is located at the bottom of the elastic device. The connecting plate is horizontally fixed on the bottom of the energy absorption plate and is connected to the support steel plate.

[0013] Preferably, a filling plate is provided between the anti-buckling energy dissipation plate and the side wall of the steel tube concrete column, and the cover plate is crimped onto the surface of the anti-buckling energy dissipation plate by a plurality of bolts and connected to the steel tube concrete column.

[0014] Preferably, the surface of the cover plate is provided with stiffening ribs.

[0015] A frame structure, the column foot node of the frame structure is provided with the self-recovering steel tube concrete column foot.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present application provides a self-recovering steel tube concrete column foot, which adopts a self-recovering device in a pre-stressed state to provide a reset function, and the anti-buckling energy dissipation device realizes the metal yield energy dissipation principle; the self-recovering device and the anti-buckling energy dissipation device are symmetrically arranged, so that the column foot has good seismic resistance and self-recovery performance; during the working stage, the self-recovering device and the anti-buckling energy dissipation device are separated from each other, and the reset function and the energy dissipation capacity are positively correlated, so that the bearing capacity is strong, and the energy dissipation capacity and self-recovery capacity are outstanding; the column foot structure is convenient to disassemble and assemble, the force is reasonable, and the performance is stable, which can realize the self-recovery and rapid recovery of functions after the earthquake. In addition, during the working process of the column foot, the rotation of the column causes the anti-buckling energy dissipation plate on the near rotating side to be compressed, and the anti-buckling energy dissipation plate on the far side is stretched and deformed, so that the anti-buckling energy dissipation plate provides a resistance to bending moment for the column foot. At the same time, the far-side elastic device produces compression deformation to provide elastic restoring force for the column foot. When the resistance bending moment provided by the elastic restoring force of the elastic device and the axial pressure is greater than the resistance bending moment provided by the anti-buckling energy dissipation plate, it is considered that the column foot can achieve self-recovery. Secondly, the column base selects different axial compression ratios, different initial preloads of elastic devices and different bending contribution ratios to meet the controllability of actual projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a schematic diagram of a self-recovering steel tube concrete column foot according to the present invention; Figure 2 This is a schematic diagram of an exploded view of a self-recovering steel tube concrete column foot according to the present invention; Figure 3 It is a schematic diagram of the buckling-resistance energy dissipation plate of the present invention; Figure 4 A load-displacement curve of a self-recovering steel tube concrete column foot according to the present invention; Figure 5 A force diagram of a self-recovering steel tube concrete column foot according to the present invention; Figure 6 The load-displacement curve of the column base specimen CB-1 test of the present invention; Figure 7 The load-displacement curve of the column base specimen CB-2 test of the present invention; Figure 8 The load-displacement curve of the column base specimen CB-3 test of the present invention; Fig. 9The load-displacement curve of the column base specimen CB-4 test of the present invention; Fig.10 The load-displacement curve of the column base specimen CB-5 test of the present invention; Fig.11 The skeleton curves of the column base specimens CB-1 to CB-5 of the present invention are compared; Fig.12 Comparison of residual deformation of column base specimens CB-1 to CB-5 in the present invention; Fig.13 The energy dissipation capacity comparison of the column base specimens CB-1 to CB-5 of the present invention is shown; Fig.14 Comparison of the experimental and theoretical load-displacement curves of the column base specimens CB-1~CB-5 of the present invention; In the figure: disc spring 1, anchor seat 2, high-strength screw 3, filling plate 4, anti-buckling energy dissipation plate 5, cover plate 6, high-strength bolt 7, support steel plate 8, ground beam 9, steel tube concrete column 10. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0021] A self-recovering steel tube concrete column foot comprises a steel tube concrete column 10, a support steel plate 8, a self-resetting device and an anti-buckling energy dissipation device.

[0022] The self-resetting device includes an elastic device and a supporting component; the steel tube concrete column 10 is arranged on the top of the support steel plate 8, the supporting component is arranged on the side wall of the steel tube concrete column 10, the elastic device is arranged on the supporting 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 the ground beam 9, and the elastic device is in a pre-stressed state; The anti-buckling energy dissipation device includes an anti-buckling energy dissipation plate 5 and a fixing device. The anti-buckling energy dissipation plate 5 is pressed against the side wall of the steel tube concrete column 10 through the fixing device, and the lower end of the anti-buckling energy dissipation plate 5 is fixedly connected to the support steel plate 8. A cover plate is provided on the side of the anti-buckling energy dissipation plate 5 away from the steel tube concrete column 10 to limit the out-of-plane buckling of the anti-buckling energy dissipation plate 5.

[0023] Under the action of frequent earthquakes, the column foot of the steel tube concrete column has no relative rotation deformation relative to the foundation, showing a rigid connection. At this time, the buckling-resistance energy-absorbing plate maintains elasticity to ensure the comfort of the building; under the action of fortified earthquakes and rare earthquakes, the column foot is allowed to rotate relative to the foundation, showing a semi-rigid connection characteristic. Relying on the plastic energy dissipation of the buckling-resistance energy-absorbing plate, the disc spring self-resetting device and the restoring force provided by the axial pressure, the column foot can be reset automatically after the earthquake. In addition, under the action of strong earthquakes, if the disc spring is compressed to the limit state, the rotation stiffness of the column foot increases sharply, and it is transformed into a traditional rigid column foot, and finally the column bottom near the rotation point will be crushed and damaged. Therefore, the expected typical characteristics of the column foot are: the buckling-resistance energy-absorbing plate enters the plastic state → the disc spring self-resetting device is limited → (self-resetting) → the column bottom near the rotation edge is crushed and damaged. The column foot provides restoring force through the pre-compressed disc spring and axial pressure, and the buckling-resistance energy-absorbing plate realizes fixed-point energy dissipation and damage concentration. After the earthquake, only the energy dissipation device needs to be replaced to quickly restore the normal function of the column foot.

[0024] In some embodiments, the elastic device is connected to the ground beam 9 through 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 supporting component and the support steel plate 8 in sequence and is fixed to the ground beam 9.

[0025] 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 arranged on the upper end of the high-strength screw. The preload of the elastic device can be adjusted by rotating the nut.

[0026] Optionally, elastic devices are provided on both symmetrical sides of the steel tube concrete column 10, and at least one elastic device is provided on each side. Several elastic devices are arranged at intervals along the side wall of the steel tube concrete column 10, and each elastic device is connected to the ground beam through a high-strength screw.

[0027] Optionally, multiple elastic devices are arranged on the same supporting component, and one supporting component may be arranged for each elastic device. Preferably, multiple elastic devices are arranged on one supporting component, which can reduce the cost of the column foot and facilitate the installation and removal of the elastic devices.

[0028] Optionally, each side wall of the steel tube concrete column 10 is provided with a self-resetting device.

[0029] Optionally, the elastic device is a coil spring, a disc spring 1, or a highly elastic rubber.

[0030] In some embodiments, the supporting component is an anchor seat 2, the top surface of the anchor seat 2 is an anchor platform for installing an elastic device, and an upwardly extending fixing plate is provided on one side of the anchor platform close to the steel tube concrete column 10, and the fixing plate is fixedly connected to the steel tube concrete column 10 by bolts, and parallel stiffening plates are provided on both sides of the bottom of the anchor platform, and one end of the stiffening plate is used to abut against the side wall of the steel tube concrete column 10.

[0031] 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. Pre-pressure is applied to both ends through a rotatable nut. The two ends of the high-strength screw 3 are connected by nuts to provide the initial pre-pressure of the disc spring self-resetting device.

[0032] In some embodiments, a weakened energy dissipation section is provided in the middle of the anti-buckling energy dissipation plate 5 so that the anti-buckling energy dissipation plate 5 forms a fixed-point energy dissipation.

[0033] A weakened energy dissipation section is provided in the middle of the buckling-resistance energy dissipation plate 5. This design makes the weakened energy dissipation section become the "soft rib" of the structure when subjected to external forces, making it more likely to deform. Due to the existence 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 energy absorption and dissipation area.

[0034] When external forces act on the steel tube concrete column, the buckling-resistance energy dissipation plate 5 absorbs and dissipates the energy through its weakened energy dissipation section. The deformation of the weakened energy dissipation section absorbs a large amount of energy and converts the energy into heat energy through plastic deformation of the material, friction, etc., thereby reducing the impact on the main structure (such as the steel tube concrete column).

[0035] Through the fixed-point energy dissipation design, the buckling-resistance energy dissipation plate 5 can effectively protect the main structure such as the steel tube concrete column from or reduce the damage of external forces. When disasters such as earthquakes occur, the weakened energy dissipation section of the buckling-resistance energy dissipation plate 5 will first deform and dissipate energy, thereby reducing the stress level of the main structure and improving its earthquake resistance.

[0036] There are three main reasons for setting weakened sections on energy dissipation panels: 1) Fixed-point energy dissipation: The weakened sections make the energy dissipation panels preferentially undergo plastic deformation in local areas under earthquake action, thus consuming earthquake energy in a concentrated manner and avoiding premature damage to the entire buckling-resistance energy dissipation panel 5 or adjacent structural components; 2) Damage control: Through the "directional design" of the weakened section, the plastic deformation under the earthquake can be limited to the preset area, reducing the damage to other key components (such as steel tube concrete columns and disc springs); 3) It is convenient to replace the energy dissipation plate after the earthquake and realize the rapid recovery of the structure. From the perspective of seismic performance, damage control and maintainability, it is necessary to set up a weakened section. It can ensure that the buckling-resistance energy dissipation plate 5 can dissipate energy efficiently, limit the scope of damage, and simplify the later repair process.

[0037] Optionally, the weakened energy dissipation section is bidirectionally symmetrically arranged in the middle of the length direction of the anti-buckling energy dissipation plate, and the weakened energy dissipation section is a groove arranged on the side wall of the anti-buckling energy dissipation plate. Preferably, grooves are arranged on both sides of the anti-buckling energy dissipation plate to balance the force on the weakened energy dissipation section.

[0038] Optionally, the anti-buckling energy absorption plate includes an energy absorption plate and a connecting plate, and has an L-shaped structure. The energy absorption plate is fixed to the side wall of the steel tube concrete 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 absorption plate. One end of the connecting plate is connected to the lower end of the energy absorption plate, and the other end extends in a direction away from the steel tube concrete column 10. The connecting plate is located at the bottom of the support steel plate and is connected by multiple bolts.

[0039] Optionally, a filling plate 4 is arranged between the anti-buckling energy absorption plate and the side wall of the steel tube concrete column 10 to form a close contact between the anti-buckling energy absorption plate and the steel tube concrete column 10, and the cover plate 6 is crimped on the surface of the anti-buckling energy absorption plate by multiple bolts, and the bolts are connected to the steel tube concrete column 10.

[0040] The cover plate is provided with stiffening ribs to further prevent out-of-plane buckling. The filler plate is a square steel plate with holes. The upper and lower ends of the filler plate, the upper end of the anti-buckling energy-absorbing plate, and the upper and lower ends of the cover plate are fixed to the column by through-through high-strength bolts. The lower end baffle of the anti-buckling energy-absorbing 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.

[0041] Optionally, when anti-buckling energy dissipation devices are provided on both symmetrical sides of the steel tube concrete column 10, the bolts pass through the steel tube concrete column 10, and the two ends of the bolts are respectively connected to the two anti-buckling energy dissipation devices.

[0042] Example 1 A self-recovering steel tube concrete column foot, the steel tube concrete column 10 has a height of 2.4m, a cross-sectional size of 300×300mm, and a steel tube wall thickness of 10mm.

[0043] The steel tube concrete column 10 is filled with C40 concrete and the external steel material is Q355 steel.

[0044] The disc spring 1 is composed of 16 disc springs, and its stiffness is 5.89 kN / mm.

[0045] The disc spring is made of 60Si2MnA alloy steel with a yield stress of 1400 MPa, an outer diameter of 80 mm, an inner diameter of 37.2 mm, a thickness of 8 mm, a free height of 10.5 mm, and a stiffness of 94.27 kN / mm.

[0046] The disc spring 1 is on the anchoring platform extending outward from the anchoring seat 2, with a 8.8-grade M36 high-strength screw 3 passing through the 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 on the lower surface of the upper flange of the ground beam 9.

[0047] The reinforcing angle steel 8 and the column are connected through 10.9-grade M24×400mm high-strength bolts 7 .

[0048] The upper part of the anti-buckling energy dissipation device is connected to the column by 12.9-grade M27×450mm high-strength bolts, the middle part is connected to the column by 10.9-grade M24×450mm high-strength bolts, and the lower part is connected to the ground beam by 10.9-grade M24×120mm high-strength bolts.

[0049] Example 2 A frame structure, the column foot node of the frame structure is provided with the self-recovering steel tube concrete column foot.

[0050] The frame structure comprises a ground beam and columns, wherein the columns are vertically arranged on the ground beam, and the self-recovering steel tube concrete column foot is installed at the node between the ground beam and the column.

[0051] The following is combined with Figure 4-5 The load-displacement curve and force mechanism of a self-recovering steel tube concrete column foot of this embodiment are described in detail: Figure 4 This is a load-displacement curve of a self-recovering steel tube concrete column foot in Example 1. In the figure, P is the horizontal load on the column top; δ is the horizontal displacement of the column top. During the working process, the column foot load-displacement curve is divided into 6 stages, considering the elastic bending deformation before the column rotates. Among them, stage 0-1 is the initial stiffness of the column foot, which is provided by the elastic deformation of the steel tube concrete column itself. When loaded to point 1, the bending moment of the column foot is equal to the initial preload of the disc spring and the bending moment provided by the axial pressure, and the column is about to rotate. As the horizontal load increases, the lateral stiffness of the column foot in stage 1-2 increases. Provides lateral stiffness to disc springs , lateral stiffness provided by axial pressure The lateral stiffness provided by the elastic stage of the buckling-resistance plate When the load reaches point 2, the buckling-resistance plate on the side away from the rotation center yields under tension and begins to deform plastically. The lateral stiffness of the column foot at stage 2-3 is Provides lateral stiffness to disc springs , lateral stiffness provided by axial pressure The lateral stiffness provided by the buckling-resistance plate in the plastic stage When the column reaches the target lateral displacement, i.e. point 3, the horizontal displacement load is the largest. Stage 3-4 is the elastic bending deformation recovery stage of the column before the column foot is unloaded and rotated, and the stiffness in this stage is the same as the initial stiffness. In stage 4-5, the buckling restraint plate on the side away from the rotation center is tensilely deformed during loading, and in this unloading stage, the buckling restraint plate is compressed and deformed again. When unloading to point 5, the buckling restraint plate begins to yield under pressure. Unloading continues to point 6, the relative rotation angle between the column and the support base is zero, and the column foot completes autonomous reset.

[0052] Figure 5 (a) is a simplified diagram of the forces when the column base is not rotated. At this time, the anti-buckling energy dissipation plate has not yet undergone axial deformation, and the force acting on the column base is zero. is the axial load of the concrete-filled steel tube column, is the initial preload of the disc spring, is the distance from the horizontal lateral displacement loading point to the surface of the foundation, is the distance from the plane of the stiffened angle steel cap to the surface of the foundation. is the column cross-sectional width, It is the distance from the center axis of the reset device to the side of the steel tube concrete column. is the rotation center. Then the separation load of the column foot is for:

[0053] When the horizontal displacement load is greater than the separation load, the column foot begins to rotate and the stress state is shown in Figure 5 (b). In the figure, , are the reaction forces of BRS-T and BRS-C plates on the column base (the resisting bending moment generated by the BRS-C plate can be ignored), is the column base angle, , They are the pressure inside the disc spring on the side away from the rotation center and the side close to the rotation center respectively.

[0054] The calculation formula of the lateral stiffness during the rotation process of the present invention is deduced as follows: 1) Axial stiffness of a single disc spring for:

[0055] in: ,

[0056] Where: , , , They are the axial stiffness, number of overlaps, number of pairs of composite disc springs and the axial stiffness of single disc springs; , , , They are respectively the axial stiffness, elastic modulus, cross-sectional area and length of the disc spring center shaft.

[0057] According to the principle of virtual work, assuming that the column foot has a unit rotation angle of 1, the column top displacement is H. When only the disc spring effect is considered, there is an equation:

[0058] The lateral stiffness provided by the disc spring is for:

[0059] 2) Lateral stiffness provided by buckling-resistance panels Elastic axial stiffness of buckling-resistance panels and plastic axial stiffness They are:

[0060]

[0061] Where: , , They are the length of the energy dissipation section, the cross-sectional area of ​​the energy dissipation section, and the elastic modulus of the buckling-resistance energy dissipation plate respectively.

[0062] As above, the lateral stiffness provided by the buckling-resistance plate can be obtained from the principle of virtual work: for:

[0063] 3) Lateral stiffness provided by axial pressure According to the principle of virtual work, the lateral stiffness provided by the axial pressure can be obtained as for:

[0064] 4) Total lateral stiffness of self-centering column foot For the overall analysis of the self-resetting column foot with preloaded disc spring, its total lateral stiffness is the superposition of the lateral stiffness provided by the disc spring, the buckling-resisting energy-absorbing plate and the axial pressure of the column, that is:

[0065] The calculation formula for the bending moment of each characteristic point during the rotation process of the present invention is deduced below, where , For feature points i The corresponding bending moment and rotation angle: When the column base is about to rotate under the action of horizontal load, its initial resistance moment is equal to the separation moment, that is:

[0066] The resisting bending moment after the column base is separated is provided by the axial pressure, the tension of the disc spring and the axial force of the buckling-resistance energy dissipation plate. The bending moment expression of characteristic points 2 to 6 is:

[0067] Where: They are respectively the axial force of the buckling-resistance plate at the column bottom rotation angle Therefore, the bending moment provided by the axial force of the buckling-resistance plate at characteristic points 2 to 6 is for:

[0068]

[0069]

[0070]

[0071]

[0072] Where: , are the pressures of the BRS-T plate when it yields in tension and compression respectively. The above calculation formula is based on the infinitesimal theory of mathematical calculus, ignoring the influence of higher-order traces.

[0073] If you want to achieve self-reset of the column foot, that is, the residual displacement of the column foot is zero, you should ,Right now:

[0074] Bending moment value of column base at each characteristic point Horizontal load on column top The following relationship exists:

[0075] Since only the elastic lateral displacement of the steel tube concrete column before loading and unloading rotation is considered, the lateral displacement of the column top at each characteristic point can be obtained: Calculation formula:

[0076] Where: is the combined flexural stiffness of the concrete-filled steel tube column.

[0077] By combining equations (2-19), we can obtain the characteristic value of the load-displacement curve of the column base throughout the entire process.

[0078] The following is combined with Figure 6-14 The performance of this embodiment is further described: Figure 6-10 The load-displacement curves of five column foot specimens with different axial compression ratios, initial preloads of disc springs and bending contribution ratios are shown in the embodiments in Table 1. Except for the hysteresis curves of specimens CB-1 and CB-2, which show a "bow shape", the hysteresis curves of CB-3~CB-5 all show a full "double flag shape", with stable energy dissipation capacity, gradually decreasing residual displacement, and better self-reset capacity. At the beginning of loading, the horizontal displacement load is small, the energy dissipation section of the buckling-resistance energy dissipation plate is still in an elastic state, and plastic energy dissipation has not occurred yet, so the area surrounded by the hysteresis loop is small, and the energy dissipation capacity is insufficient; as the horizontal displacement load increases, the strain of the buckling-resistance energy dissipation plate increases, and it begins to yield and dissipate energy after exceeding the elastic range, so the area enclosed by the hysteresis curve gradually increases, and the energy dissipation capacity of the column foot gradually increases. At the same time, the hysteresis curves of specimens CB-1 and CB-2 are significantly different in terms of pinching degree and overall shape compared to specimens CB-3~5, while the load-displacement curves of specimens CB-3~5 are similar in terms of pinching degree and overall shape. This shows from a macroscopic level that the influence of the axial compression ratio on the seismic performance of the column base is stronger than the initial preload of the disc spring.

[0079] Table 1 Specimen parameters

[0080] Fig.11The skeleton curves of the column foot specimens CB-1~CB-5 of the present invention are compared, and the overall trends of the skeleton curves of each specimen are basically the same. In the early stage of loading, the column foot did not rise, and the lateral displacement of the column top was caused by the elastic bending deformation of the column, so the initial stiffness of each specimen was large and in a straight line state. Increasing the axial compression ratio of the column and the initial preload of the disc spring can increase the separation load and yield load of the column foot, and the influence of the axial compression ratio on the separation load and yield load of the column foot is more significant than that of the disc spring preload. In addition, when the horizontal load on the top of the column exceeds the separation load, the column foot rotates, and the energy dissipation section of the buckling-resistant energy dissipation plate gradually transitions from an elastic state to a plastic state, resulting in a gradual decrease in the stiffness of the column foot, showing that it has 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 foot can be effectively improved, thereby enhancing its bearing stability. Increasing the axial compression ratio of the column and the initial preload of the disc spring can both increase the bearing capacity of the column foot, and increasing the initial preload of the disc spring is 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 foot is determined by the buckling-resistant plate and the disc spring; in the later stage of loading, when the full cross-section of the energy-absorbing section of the buckling-resistant plate yields, the contribution of the buckling-resistant plate to the stiffness of the column foot no longer increases, and the change in the stiffness of the column foot depends on the stiffness of the disc spring; while increasing the initial preload of the disc spring, in addition to increasing the vertical load of the column foot, the stiffness of the disc spring is also increased.

[0081] Fig.12 The residual deformation comparison of the column foot specimens CB-1~CB-5 in the present invention shows that when the inter-story displacement angle reaches 2.00%, except for the residual deformation of specimens CB-1 and CB-2 greater than 0.2%, the other specimens meet the self-reset performance requirements and have good self-reset capabilities. When the inter-story displacement angle reaches 3.00%, the residual deformations of the specimens are 2.06%, 0.61%, 0.31%, 0.21% and 0.19%, respectively. Among them, the residual deformations of specimens CB-4 and CB-5 are still close to 0.2%, indicating that the specimens can still maintain a small residual deformation under the action of a large earthquake, which is conducive to the rapid recovery of the post-earthquake function of the column foot. At the same time, the residual deformations of specimens CB-2 and CB-3 are reduced by 70.61% and 84.80% respectively compared with CB-1, while the residual deformations of specimens CB-4 and CB-5 are reduced by 32.89% and 39.80% respectively compared with CB-3. This shows that increasing the axial pressure ratio of the column and the initial preload of the disc spring within a certain range can improve its self-resetting ability, and increasing the axial pressure ratio of the column can improve the self-resetting ability more significantly than increasing the initial preload of the disc spring.

[0082] Fig.13The energy dissipation capacity of the column foot specimens CB-1~CB-5 of the present invention is compared. When the horizontal displacement load is small, the buckling-resistance energy dissipation plate is in an elastic state, so the energy dissipation capacity is low; as the load increases, the buckling-resistance energy dissipation plate enters the yield energy dissipation, and the energy dissipation capacity of each specimen gradually increases and is maintained at a high level. When the horizontal displacement load reaches 60mm (3.00% displacement angle), the energy dissipation of specimens CB-2 and CB-3 is 4.28% and 12.28% lower than that of specimen CB-1, respectively; the energy dissipation of specimens CB-4 and CB-5 is 3.20% and 6.83% lower than that of specimen CB-3, respectively. Therefore, the energy dissipation capacity and equivalent viscous damping coefficient of the column foot will be reduced by increasing the axial pressure ratio and the initial preload of the disc spring, and increasing the axial pressure ratio has a more significant effect on the energy dissipation capacity and the equivalent viscous damping coefficient.

[0083] Fig.14 The column foot specimens CB-1~CB-5 of the present invention are compared with the theoretical load-displacement curve. According to the column foot load-displacement curve calculation formula, the corresponding horizontal loads of the specimens CB1~CB5 are calculated. The experimental results are compared with the theoretical results. The fitting effect of the experimental results and the theoretical results is good, and the calculation errors are within 15%, only The calculation error is large, resulting in the stiffness of the restoring force theoretical model in the early stage of unloading being slightly greater than the test value. The reasons are: first, in the actual test, there is a small gap between the fixing bolts and the hole wall of the anti-buckling energy dissipation plate, which leads to insufficient contact in the early stage of unloading, resulting in a slight reduction in the stiffness of the column foot in the local range; second, during the operation of the anti-buckling energy dissipation device, there is mutual friction between the anti-buckling energy dissipation plate and the cover plates and filling plates on both sides.

[0084] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A self-recovering steel tube concrete column base, characterized in that: It includes a steel tube concrete column, a support steel plate, a self-resetting device and an anti-buckling energy dissipation device; The self-resetting device includes an elastic device and a supporting component; the steel tube concrete column is arranged on the top of the support steel plate, the supporting component is arranged on the side wall of the steel tube concrete column, the elastic device is arranged on the supporting 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 the ground beam, and the elastic device is in a pre-stressed state; The anti-buckling energy dissipation device includes an anti-buckling energy dissipation plate and a fixing device. The anti-buckling energy dissipation plate is pressed against the side wall of the steel tube concrete column through the fixing device, and the lower end of the anti-buckling energy dissipation plate is fixedly connected to the support steel plate. A cover plate is arranged on the side of the anti-buckling energy dissipation plate away from the steel tube concrete column to limit the out-of-plane buckling of the anti-buckling energy dissipation plate.

2. The self-recovering steel tube concrete column base according to claim 1, characterized in that: The elastic device is connected to the ground beam through a screw assembly, and the screw assembly includes a screw and a nut; The upper end of the screw is connected to the upper end of the elastic device, the lower end of the screw passes through the supporting component and the bearing steel plate in sequence and is fixed to the ground beam, and the nut is connected to the upper end of the screw for fixing the elastic device and adjusting the preload.

3. The self-recovering steel tube concrete column base according to claim 1, characterized in that: The elastic device is a spiral spring, a disc spring, or a high-elastic rubber.

4. The self-recovering steel tube concrete column base according to claim 1, characterized in that: The supporting component includes an anchor seat, the top surface of the anchor seat is an anchor platform for installing an elastic device, an upwardly extending fixing plate is arranged on one side of the anchor platform close to the steel tube concrete column, and mutually parallel stiffening plates are arranged on both sides of the bottom of the anchor platform, and one end of the stiffening plate is used to abut against the side wall of the steel tube concrete column.

5. The self-recovering steel tube concrete column base according to claim 1, characterized in that: The energy-dissipating sections are symmetrically arranged on both sides of the anti-buckling energy-dissipating plate, so that the anti-buckling energy-dissipating plate forms fixed-point energy dissipation.

6. The self-recovering steel tube concrete column base according to claim 5, characterized in that: The energy-dissipating weakening section is a groove arranged on the side wall of the anti-buckling energy-dissipating plate.

7. The self-recovering steel tube concrete column base according to claim 1, characterized in that: The buckling-resistance energy-absorbing plate comprises an energy-absorbing plate and a connecting plate. The energy-absorbing plate is fixed on the side wall of the steel tube concrete column and is located at the bottom of the elastic device. The connecting plate is horizontally fixed on the bottom of the energy-absorbing plate and is connected to the support steel plate.

8. The self-recovering steel tube concrete column base according to claim 1, characterized in that: A filling plate is arranged between the anti-buckling energy dissipation plate and the side wall of the steel tube concrete column. The cover plate is pressed on the surface of the anti-buckling energy dissipation plate by a plurality of bolts and is connected to the steel tube concrete column.

9. The self-recovering steel tube concrete column base according to claim 1, characterized in that: The surface of the cover plate is provided with stiffening ribs.

10. A frame structure, characterized in that: The column base node of the frame structure is provided with a self-recovering steel tube concrete column base as described in any one of claims 1-9.

Images