CN117552579A

CN117552579A - SMA-based buckling-restrained steel pipe concrete column and construction method thereof

Info

Publication number: CN117552579A
Application number: CN202311515668.5A
Authority: CN
Inventors: 吴轶; 刘焕峰; 李心悦; 李天贤
Original assignee: Guangdong Haohua Construction Engineering Co ltd; Guangzhou University
Current assignee: Guangdong Haohua Construction Engineering Co ltd; Guangzhou University
Priority date: 2023-11-14
Filing date: 2023-11-14
Publication date: 2024-02-13

Abstract

The invention provides an SMA-based buckling-restrained steel pipe concrete column and a construction method thereof, and relates to the technical field of engineering structures. According to the technical scheme, the self-resetting effect of the SMA wire is fully exerted by the SMA wire mesh ring through the super elasticity of the SMA wire mesh ring, so that the steel pipe at the bottom of the column shaft can be prevented from buckling prematurely, and the bulging degree of the steel pipe of the column shaft is controlled. When in small and medium earthquake, the SMA silk screen ring restrains the steel pipe at the bottom from buckling, and solves the problem that the bottom of the steel pipe is easy to generate local buckling. When the steel pipe is in out-of-plane buckling under the action of large and ultra-large earthquake, the steel pipe can be compressed and reset by utilizing the super elasticity of the SMA, the residual deformation is reduced, the earthquake energy can be dissipated by utilizing the high damping characteristic of the shape memory alloy, and the buckling-restrained steel pipe concrete column is truly realized.

Description

SMA-based buckling-restrained steel pipe concrete column and construction method thereof

Technical Field

The invention relates to the technical field of engineering structures, in particular to an SMA-based buckling-restrained steel pipe concrete column and a construction method thereof.

Background

The steel tube concrete column is a combined structural member with wide application, and compared with the traditional reinforced concrete column, the combined steel tube concrete column has high bearing capacity, simple construction and good hysteresis and energy consumption performance. The basic principle of the steel tube concrete column is that the possibility of inward buckling of the steel tube is weakened by means of the supporting effect of the internally filled concrete, and the stability of the column body steel tube is enhanced. Meanwhile, the core concrete is restrained by the steel pipe, so that the core concrete is in a three-way compression state, the generation and development time of longitudinal cracks in the concrete are delayed, and the core concrete has stronger compressive strength and deformation resistance.

Compared with square or rectangular steel tube concrete columns, the circular steel tube concrete column has uniform centripetal force on the concrete in the core area, and the steel tube has only annular tensile force without bending deformation under the action of outward extrusion of the concrete in the core area, so that the constraint effect is optimal.

The test researches at home and abroad show that in order to reduce the dead weight and thickness of the column body, the existing steel tube concrete column adopts thin-wall steel tubes for the outer layer steel plates, and the thin-wall steel tubes are easy to locally unstably damage, so that the steel tubes cannot play a role in restraining core concrete, and the problem of too fast bearing capacity reduction exists.

As shown in fig. 5, when the bottom of the steel tube concrete column is subjected to axial pressure or reciprocating load, local buckling is likely to occur, and the column body steel tube is subject to bulging. This can lead to the problem that the steel pipe cannot exert a proper restraining effect on the core concrete and the bearing capacity drops too rapidly.

In order to solve the problem of local buckling of the thin-wall steel pipe, the method is mainly used for solving the problems of external reinforcement concrete jacket, external steel plate, FRP (fiber reinforced composite) package reinforcement and the like outside the steel pipe concrete. The traditional method for reinforcing the enlarged section is that the external reinforced concrete sleeve needs to be subjected to formwork erection and form disassembly, the reinforced bars are bound, the construction steps are complicated, the external steel sleeve and the external steel plate need to be subjected to later maintenance, and the self weight of the structure is greatly improved. The FRP wrapping reinforcement construction is more convenient, but when the FRP constraint is too large, the FRP is easily damaged in advance due to the influence of the buckling of the steel pipe, the material performance of the FRP cannot be effectively utilized, and the ductility performance is poor.

Shape Memory Alloys (SMA) have the shape memory effect and the superelastic effect, and in recent years are widely used in the fields of aviation, offshore, medicine, civil engineering and the like, and have good fatigue resistance and energy consumption capability in large deformation cycles. Shape memory effects are those in which certain alloys with thermoelastic martensitic transformation have a limited deformation in the martensitic state or after deformation induces martensite, when the heating temperature exceeds the temperature at which the martensite phase disappears, the material fully recovers the shape and volume before deformation. The superelastic effect is that the shape memory alloy can return to the original parent phase state under the condition of no heating when unloaded in a certain strain range, and the strain can completely disappear, but the strain quantity is far beyond the elastic deformation in the normal sense, and the shape memory alloy shows superelasticity. The two characteristics play roles in applying prestress to structural members, reducing residual deformation, improving energy consumption capacity and the like.

The shape memory alloy has good stress performance. The tensile strength of the nickel-titanium memory alloy is about 450-850 MPa, the yield strength is about 195-690 MPa, the maximum recovery stress of reverse transformation can reach 400MPa, and the maximum recovery strain can reach 8 percent under the influence of factors such as the diameter of the SMA, the content of nickel, the ambient temperature, the loading frequency, the strain amplitude, the material strength and the like. Taking 1 mNI49.8Ti50.2SMA as an example, the yield strength is about 300MPa, the tensile strength is about 500MPa when the strain is 6%, and the tensile strength is about 700MPa when the strain is 8%. Shape memory alloys have superior ductility, energy dissipation and resistance to deformation at the same material strength as conventional steels. In actual engineering, SMA wires with different strength and different diameters can be selected according to actual conditions so as to achieve different constraint effects.

In chinese patent CN114908991a published by 2022-08-16, a transverse prestress reinforcement structure and a reinforcement method for a circular concrete column are proposed, and the reinforcement effect on the concrete column is achieved by bending and wrapping a shape memory alloy plate on the outer side of the circular concrete column. However, the prior art does not adopt a steel pipe to restrict the concrete column, but directly uses a shape memory alloy plate to bend and wrap the cracking part of the concrete column, so the shape memory alloy plate only plays the same role as the steel pipe in practice, namely, the cracking of the concrete column is restricted and reinforced, and the problem of local buckling of the concrete column cannot be solved; and such prior art does not provide special reinforcement for the buckling restrained position of the concrete filled steel tubular column.

Disclosure of Invention

The invention aims to provide an SMA-based buckling-restrained steel pipe concrete column and a construction method thereof, which can solve the problem of local buckling of the steel pipe concrete column.

The invention provides an SMA-based buckling-restrained steel pipe concrete column which comprises a steel pipe, wherein concrete is filled in the steel pipe to form the steel pipe concrete column, and an SMA wire mesh ring is wrapped on the outer side of a buckling-restrained range of the lower part of the steel pipe concrete column.

Further, the SMA wire mesh ring is wrapped in the lower 1/3 range of the steel tube concrete column.

Further, the SMA silk screen ring is formed by connecting an annular structure after the SMA silk screen is woven by an SMA silk screen.

Further, the SMA silk screen is of a three-way grid structure, meshes with uniform sizes are formed on the SMA silk screen, and the meshes are of an equilateral triangle shape.

Further, the SMA wire is made of a shape memory alloy material with the austenite phase transition ending temperature Af far lower than room temperature.

Further, the SMA wire is made of NiTi alloy, and the Ni content in the NiTi alloy is 49.8%.

Further, the SMA wire mesh ring is always in a tension state, and the steel tube concrete column is always in a compression state.

The invention also provides a construction method of the SMA-based buckling-restrained steel pipe concrete column, which comprises the following steps: s1, prefabricating column steel pipes in a factory; s2, prefabricating an SMA wire; s3, weaving the SMA wire into an SMA wire mesh, and then manufacturing the SMA wire mesh into an annular structure form, namely manufacturing an SMA wire mesh ring; s4, performing shape memory treatment on the SMA silk screen ring: processing an SMA wire mesh ring into an austenite phase with the perimeter size smaller than the cross section of the steel tube concrete column at normal temperature; processing the SMA wire mesh ring into a martensite phase with the perimeter size larger than the cross section of the concrete filled steel tube column in a low-temperature state; s5, sleeving a martensitic phase SMA wire mesh ring with the perimeter size larger than the cross section of the steel tube concrete column to the outer side of the buckling range of the lower part of the steel tube in a low-temperature environment; s6, transporting the column shaft steel pipe sleeved with the SMA wire mesh ring to a construction site at normal temperature; s7, directly taking the column shaft steel tube as a concrete pouring template at a construction site, and filling concrete to form a concrete column.

Further, in step S2, the SMA wire is subjected to a plurality of loading and unloading cycles.

Further, in the step S4, processing the SMA wire mesh ring into an austenite phase with the circumference size of 5-8% smaller than the cross section circumference of the steel tube concrete column at normal temperature; and in a low-temperature state, processing the SMA wire mesh ring into a martensite phase which is 5% -8% larger than the perimeter size of the cross section of the steel tube concrete column.

According to the technical scheme, the self-resetting effect of the SMA wire is fully exerted by the SMA wire mesh ring through the super elasticity of the SMA wire mesh ring, so that the steel pipe at the bottom of the column shaft can be prevented from buckling prematurely, and the bulging degree of the steel pipe of the column shaft is controlled. When in small and medium earthquake, the SMA silk screen ring restrains the steel pipe at the bottom from buckling, and solves the problem that the bottom of the steel pipe is easy to generate local buckling. When the steel pipe is in out-of-plane buckling under the action of large and ultra-large earthquake, the steel pipe can be compressed and reset by utilizing the super elasticity of the SMA, the residual deformation is reduced, the earthquake energy can be dissipated by utilizing the high damping characteristic of the shape memory alloy, and the buckling-restrained steel pipe concrete column is truly realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic top view of the present invention;

FIG. 2 is a schematic front and side view of the present invention;

FIG. 3 is an internal construction view of the present invention;

FIG. 4 is a schematic illustration of the SMA wire mesh weave of the present invention;

FIG. 5 is a schematic view of the bottom part of a concrete filled steel tubular column in the background art;

reference numerals illustrate:

1-a steel pipe; 2-filling concrete into the steel pipe; 3-SMA wire mesh ring; 4-SMA wire mesh; 401-braze joint;

Detailed Description

The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise. Furthermore, the terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

Example 1

The invention provides an SMA-based buckling-restrained steel pipe concrete column which comprises a steel pipe 1, wherein concrete 2 is filled in the steel pipe 1 to form the steel pipe concrete column, and an SMA wire mesh ring 3 is wrapped on the outer side of a buckling-easy range of the lower part of the steel pipe concrete column.

Specifically, the column body steel tube 1 is formed by welding in a factory, the steel tube 1 can be selected from but not limited to a round steel tube 1, a square steel tube 1 and other steel tubes 1 with regular shapes, the section shape of the steel tube 1 is kept unchanged within the wrapping range of the SMA wire mesh ring 3, the condition that the volume of the steel tube 1 is retracted does not exist, and the column body steel tube 1 of the steel tube concrete column is effectively wrapped by the SMA wire mesh ring 3.

The cylindrical steel pipe 1 is preferably made of Q355, Q390, Q420 and Q460 steel. The height and the diameter of the steel pipe concrete column, the material strength of the steel pipe 1 and the strength of the concrete 2 are not fixed, and can be adjusted according to the stress of the actual engineering requirement, so that different bearing capacity and ductile energy consumption capacity are realized, and engineering personnel can conveniently realize different performance level requirements of the structure according to the design requirement of the actual structure.

Correspondingly, the form of the SMA wire mesh ring 3 can be selected from a circular mesh ring, a square mesh ring and the like, and the form of the mesh ring is the same as that of the column shaft steel pipe 1. The method has the effects of delaying the occurrence of local buckling of the steel tube concrete column and reducing the buckling degree of the steel tube 1. In this embodiment 1, the column steel tube 1 selects a circular steel tube 1, the sma wire mesh ring 3 selects a circular net ring shape, the circular section steel tube concrete column is compared with a square or rectangular steel tube concrete column, the constraint force of the circular steel tube 1 to the concrete 2 in the core area is uniform centripetal force, and the steel tube 1 only has the circumferential tension without bending deformation under the action of the outward extrusion of the concrete 2 in the core area, so that the constraint effect is optimal.

SMA (shape memory alloys), i.e. shape memory alloy, has superelastic and shape memory properties. In this example 1, the shape memory property of the SMA wire mesh ring 3 was used to provide the pre-compression stress to the column body steel pipe 1, and the buckling resistance of the novel steel pipe concrete column was enhanced. The restoring force generated by the martensitic transformation of the SMA wire mesh ring 3 can apply pre-compression stress to the pipe wall at the bottom of the steel pipe concrete column, so that the restraint effect on the steel pipe 1 is enhanced, and the occurrence of local buckling of the steel pipe 1 is delayed. By utilizing the super elasticity of the SMA wire mesh ring 3, the outer wrapping SMA wire mesh ring 3 is always in a tension state, so that the SMA wire ring can fully exert the self-resetting and energy consumption effects, effectively consume the seismic energy and reduce the residual deformation. The bottom steel tube 1 of the steel tube concrete column is prevented from buckling prematurely under the action of small and medium vibration, and the problem that local buckling is easy to occur at the bottom of the steel tube 1 is solved. And under the action of large earthquake or super-large earthquake, the bottom steel tube 1 is self-restored, and the buckling-restrained steel tube concrete column is truly realized.

Example 2

The SMA wire mesh ring 3 is wrapped at the lower 1/3 range of the steel pipe concrete column.

Specifically, as shown in fig. 5, when the bottom of the steel tube concrete column is subjected to axial pressure or reciprocating load, local buckling is likely to occur, and the column body steel tube 1 is subject to buckling. This causes a problem that the steel pipe 1 cannot exert a proper restraining effect on the core concrete 2 and the load bearing capacity is lowered too rapidly. Therefore, in this example 2, the SMA wire mesh ring 3 was wrapped around the lower portion 1/3 of the steel tube concrete column, and local buckling was likely to occur in the steel tube concrete column in this range. By utilizing the shape memory property of the SMA wire mesh ring 3, restoring force generated by martensite reverse transformation can apply pre-compression stress to the column body steel tube 1 of the steel tube concrete column, and the column body steel tube 1 is subjected to circumferential constraint, and the schematic diagram is shown in figure 1. The SMA wire mesh ring 3 can strengthen the restraint effect on the steel pipe 1, delay the appearance of buckling of the lower part of the steel pipe 1, enable the core area concrete 2 to be in a three-way pressed state, and effectively improve the strength of the concrete 2.

Example 3

The SMA wire mesh ring 3 is formed by weaving SMA wires into SMA wire mesh 4 and then connecting the SMA wire mesh 4 into an annular structure.

Specifically, the shape of the SMA wire mesh ring 3 is the same as the shape of the column steel tube 1, and a circular mesh ring, a square mesh ring or the like can be selected. The connection mode is selected from, but not limited to, mechanical connection, welding, binding connection and the like with the same good connection effect, for example, the SMA wire mesh 4 is formed into a circular mesh ring by means of brazing connection 401, and the brazing connection 401 is one of the most common SMA connection modes at present.

The SMA wire diameter adopted for programming the SMA wire mesh 4 is selected from but not limited to thin SMA wires with the diameters of 0.3mm, 0.5mm, 1mm and the like, preferably 1mm, and the thicker the diameter is, the larger the residual deformation is, the worse the energy consumption capability is aiming at the performance of the SMA, so the SMA wire is selected for programming the SMA wire mesh 4, the self-resetting and energy consumption characteristics of the shape memory alloy can be brought into play, the consumption of the SMA alloy can be effectively saved, and the manufacturing cost is reduced.

Example 4

The SMA silk screen 4 is a three-way grid structure, and is provided with meshes with uniform sizes, the meshes are in the shape of equilateral triangles, and the stress is uniform.

Specifically, the SMA wire mesh 4 may be, but is not limited to, a three-way mesh, a crochet mesh, a plain weave mesh, a twill weave mesh, a netherlands weave mesh, a multiple weave mesh, or a mesh structure with the same good tensile properties. Grid size the grid size is preferably 2.5-5 cm, more specifically the grid size is selected to be 4cm x 4cm, and all nodes inside are fixed by adopting brazing connection 401.

The braided SMA wire mesh 4 is preferably dense and not sparse, if too dense SMA wire mesh 4 leads to higher manufacturing cost, too sparse SMA wire mesh 4 reduces the restraint effect on the steel tube concrete column.

Example 5

The SMA wire is made of a shape memory alloy material with the austenite phase transition ending temperature Af far lower than the room temperature, so that the SMA wire is stabilized in an austenite state at the room temperature. The SMA wire is made of NiTi alloy, and the Ni content in the NiTi alloy is 49.8%.

Specifically, the SMA wire material may be, but is not limited to, a material having the same function, such as a Ni-Ti alloy, a Ni-Al alloy, a Cu-Al-Ni alloy, or the like. Among the shape memory alloys NiTi alloys and copper-based alloys that have been put into practical use at present, niTi alloys are preferred. Compared with copper alloy, niTi alloy has stronger recovery strain capacity, larger recovery stress, longer cycle life, better corrosion resistance and easier shape memory treatment. Because the maximum recoverable elastic strain of the NiTi-based shape memory alloy is about 8%, if the maximum recoverable elastic strain exceeds 8%, unrecoverable residual deformation can be generated, and the constraint effect of the SMA wire mesh ring 3 on the steel tube concrete column is reduced. The NiTi alloy is preferably Ni with about 49.8% Ni _49.8 Ti _50.2 When the Ni content is increased, the energy consumption of the SMA wire is slightly reduced, and the residual deformation is multiplied.

Example 6

The SMA wire mesh ring 3 is always in a tension state, and the steel tube concrete column is always in a compression state.

Specifically, the section shape of the steel tube 1 is kept unchanged within the wrapping range of the SMA wire mesh ring 3, the condition that the volume of the steel tube 1 is retracted does not exist, and the column body steel tube 1 of the steel tube concrete column is ensured to be effectively wrapped by the SMA wire mesh ring 3. The SMA silk screen 4 is always in a tension state, and the steel tube concrete column is always in a compression state, so that local buckling is avoided.

Example 7

The invention also provides a construction method of the SMA-based buckling-restrained steel pipe concrete column, which comprises the following steps:

s1, prefabricating a column steel pipe 1 in a factory; the thickness and the height of the column steel pipe 1 depend on actual requirements. If the steel pipe 1 is made into a circular section, the outer diameter of the steel pipe 1 should not be smaller than 200mm, the wall thickness should not be smaller than 4mm, and the ratio of the outer diameter to the wall thickness, the section steel content and the constraint effect coefficient should meet the relevant requirements of the technical standard of the concrete 2 mixing structure of the steel pipe 1. If the outer diameter of the steel pipe 1 is greater than or equal to 2000mm, it is preferable to adopt structural measures for reducing shrinkage of the concrete 2 in the steel pipe 1, such as setting of pegs, stiffening ribs, and the like.

S2, prefabricating an SMA wire; the SMA wire is made of a shape memory alloy material with the austenite phase transition ending temperature Af of a proper diameter far lower than room temperature. To ensure a better superelastic performance of the SMA wire, it is subjected to about 10 loading and unloading cycles, i.e. mechanical exercises. The SMA wires with different strength and different diameters can be selected according to actual use requirements so as to achieve different constraint effects.

S3, weaving the SMA wire into an SMA wire mesh 4, and then manufacturing the SMA wire mesh 4 into an annular structure form, namely manufacturing an SMA wire mesh ring 3; and prefabricating the SMA silk screen 4, selecting proper mesh size, weaving the SMA silk screen into a three-way grid structure, wherein the three-way grid is of an equilateral triangle, and the grid stress can be ensured to be uniform. The SMA wire mesh 4 is preferably 1/3 of the height of the column shaft. And selecting a proper connection mode to manufacture the woven SMA silk screen 4 into a ring-shaped structure form, namely manufacturing the SMA silk screen ring 3. The annular structure form can be a circular annular form, a square annular form and the like, and the annular structure form is the same as the form of the column shaft steel tube 1. The SMA wire mesh ring 3 can change the grid density, the mesh type, the mesh height and the like according to specific requirements, has wide application range and does not influence the normal construction and use of the steel tube concrete column.

S4, performing shape memory treatment on the SMA wire mesh ring 3 in a shape memory alloy professional processing factory: processing the SMA wire mesh ring 3 into an austenite phase with the circumference of which the size is 5% -8% smaller than the cross section circumference of the steel tube concrete column at normal temperature; under the low temperature state, the SMA wire mesh ring 3 is processed into a martensite phase which is 5% -8% larger than the perimeter size of the cross section of the concrete filled steel tube column;

s5, in a low-temperature environment of a factory, sleeving a martensitic phase SMA wire mesh ring 3 with the circumference size of 5% -8% larger than the cross section of the steel pipe concrete column to the outer side of a buckling-easy range with the height of 1/3 of the lower part of the steel pipe 1; and then, the SMA wire mesh ring 3 is warmed to the room temperature, when the temperature of the SMA wire mesh ring 3 is warmed to the room temperature, the SMA wire mesh ring 3 is restored to an austenite phase smaller than the size of the steel pipe concrete column, and is tightly wrapped at the bottom of the steel pipe concrete column to provide the pre-compression stress for the column body steel pipe 1, namely, the pre-compression stress can be applied to the column body steel pipe 1 under the condition of no heating and no external force.

S6, after the SMA wire mesh ring 3 is sleeved in a factory, transporting the column shaft steel pipe 1 (not poured with concrete 2) sleeved with the SMA wire mesh ring 3 to a construction site at normal temperature; and meanwhile, purchasing the column body filled concrete 2 with proper strength and transporting to a construction site.

S7, directly taking the column steel tube 1 as a concrete 2 pouring template at a construction site, finishing pouring and vibrating of the concrete 2 filled in the steel tube 1, and curing the concrete 2.

The working principle of the invention is as follows:

the column body round steel pipe 1 is restrained at the outer side of the concrete 2 filled in the steel pipe 1, so that the concrete 2 in the core area is in a three-way compression state, and the strength of the concrete 2 is effectively enhanced. The SMA wire mesh ring 3 wraps the bottom 1/3 of the steel tube concrete column in the height range, and provides pre-compression stress for the tube wall at the bottom of the column body circular steel tube 1. When the steel pipe 1 is buckled, the SMA wire mesh ring 3 is always in tension. Under the action of small earthquake and medium earthquake, the bottom steel pipe 1 is prevented from buckling prematurely, and under the action of large earthquake and super-large earthquake, even if the steel pipe 1 is buckled out of plane, the super-elasticity of the SMA can be utilized to compress and reset the steel pipe 1, reduce residual deformation, and also utilize the high damping characteristic of the SMA to dissipate earthquake energy.

Therefore, the invention utilizes the shape memory characteristic of the SMA wire mesh ring 3, and the restoring force generated by martensite reverse transformation can apply pre-compression stress to the column body steel tube 1 of the steel tube concrete column, thereby playing a role in circumferential restraint on the column body steel tube 1. The SMA silk screen 4 can strengthen the restraint effect on the steel pipe 1, delay the appearance of the local buckling of the steel pipe 1, enable the concrete 2 in the core area to be in a three-way pressed state, and effectively improve the strength of the concrete 2. By utilizing the super elasticity of the SMA wire mesh ring 3, the SMA wire mesh ring 3 is wrapped in a tension state, so that the SMA wire can fully exert the self-resetting effect. During small and medium earthquake, the SMA wire mesh ring 3 restrains the bottom steel pipe 1 from buckling, and solves the problem that the bottom of the steel pipe 1 is easy to generate local buckling. When the steel pipe 1 has out-of-plane buckling under the action of large and ultra-large earthquake, the steel pipe 1 can be compressed and reset by utilizing the super elasticity of SMA, the residual deformation is reduced, the earthquake energy can be dissipated by utilizing the high damping characteristic of the shape memory alloy, and the buckling-restrained steel pipe concrete column is truly realized.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. The SMA-based buckling-restrained steel pipe concrete column is characterized by comprising a steel pipe, wherein concrete is filled in the steel pipe to form the steel pipe concrete column, and an SMA wire mesh ring is wrapped on the outer side of the buckling-restrained range of the lower portion of the steel pipe concrete column.

2. An SMA-based buckling restrained concrete-filled steel tube column according to claim 1, wherein the SMA wire mesh ring is wrapped around the lower 1/3 extent of the concrete-filled steel tube column.

3. An SMA-based buckling restrained concrete-filled steel tube column according to claim 1, wherein the SMA wire mesh rings are formed by connecting SMA wire mesh woven from SMA wires into an annular structure.

4. An SMA-based buckling restrained concrete-filled steel tube column according to claim 3, wherein the SMA wire mesh is of a three-way grid structure with evenly sized mesh openings in the shape of equilateral triangles.

5. An SMA-based buckling restrained concrete-filled steel tube column according to claim 3, wherein the SMA wire is made of a shape memory alloy material with an austenite transformation ending temperature Af well below room temperature.

6. The SMA-based buckling restrained concrete-filled steel tube column according to claim 1, wherein the SMA wire is made of NiTi alloy, and the Ni content in the NiTi alloy is 49.8%.

7. An SMA-based buckling restrained concrete-filled steel tube column according to claim 1, wherein the SMA wire mesh rings are always in tension and the concrete-filled steel tube column is always in compression.

8. A method of constructing an SMA-based buckling restrained concrete-filled steel tube column according to claim 1, comprising the steps of:

s1, prefabricating column steel pipes in a factory;

s2, prefabricating an SMA wire;

s3, weaving the SMA wire into an SMA wire mesh, and then manufacturing the SMA wire mesh into an annular structure form, namely manufacturing an SMA wire mesh ring;

s4, performing shape memory treatment on the SMA silk screen ring: processing an SMA wire mesh ring into an austenite phase with the perimeter size smaller than the cross section of the steel tube concrete column at normal temperature; processing the SMA wire mesh ring into a martensite phase with the perimeter size larger than the cross section of the concrete filled steel tube column in a low-temperature state;

s5, sleeving a martensitic phase SMA wire mesh ring with the perimeter size larger than the cross section of the steel tube concrete column to the outer side of the buckling range of the lower part of the steel tube in a low-temperature environment;

s6, transporting the column shaft steel pipe sleeved with the SMA wire mesh ring to a construction site at normal temperature;

s7, directly taking the column shaft steel tube as a concrete pouring template at a construction site, and filling concrete to form a concrete column.

9. The method according to claim 8, wherein in step S2, the SMA wire is subjected to a plurality of loading and unloading cycles.

10. The construction method according to claim 8, wherein in step S4, the SMA wire mesh ring is processed into an austenite phase smaller than 5% -8% of the circumference of the cross section of the concrete filled steel tubular column at normal temperature; and in a low-temperature state, processing the SMA wire mesh ring into a martensite phase which is 5% -8% larger than the perimeter size of the cross section of the steel tube concrete column.