CN110629897A

CN110629897A - Multi-stage energy-consumption post-tensioning self-resetting node and assembling method thereof

Info

Publication number: CN110629897A
Application number: CN201910868575.8A
Authority: CN
Inventors: 张萍; 柯珂; 任志浩; 周绪红
Original assignee: Hunan University; Chongqing University
Current assignee: Hunan University; Chongqing University
Priority date: 2019-09-16
Filing date: 2019-09-16
Publication date: 2019-12-31

Abstract

The invention discloses a multi-stage energy-consuming post-tensioning self-resetting node and an assembling method thereof, wherein the node can slide relatively, energy consumption is provided in a mode of single-side friction of a T-shaped piece and a beam flange under small deformation, an SMA damper connected with a T-shaped plate starts to enter a phase change energy consumption stage along with the increase of the deformation of an opening of the node, and the introduced metal damper cannot increase the residual deformation of the node under the same prestress level; in order to avoid the characteristic of low redundancy of the post-tensioning node, the bolt rod for connecting the T-shaped piece and the beam flange and the wall of the beam flange long circular hole are allowed to contact and bear pressure through the long circular hole, and the anti-collapse device can still effectively resist collapse under extreme conditions. Under the condition of small to medium earthquakes, the energy consumption is carried out by utilizing friction damping, the energy consumption of a combined energy consumption mode is realized by cooperating with SMA phase change under the condition of medium to large earthquakes, and the complete reset is realized by means of post-tensioning prestressed tendons; under extreme conditions, the node force transmission is converted into a hole wall pressure-bearing mode to resist collapse, and the properties of multi-stage energy consumption and multiple redundancy are realized.

Description

Multi-stage energy-consumption post-tensioning self-resetting node and assembling method thereof

The technical field is as follows:

the invention belongs to the field of structural engineering, and particularly relates to a post-tensioning self-resetting node based on multi-stage energy consumption of an SMA damping and friction mechanism and an assembling method thereof.

Background art:

the steel has the characteristics of light weight, high strength, high elastic modulus and high toughness, and is widely applied to the field of structural engineering, particularly complex long-span structures such as bridges and gymnasiums. Compared with steel structure members, the connection parts of the members are stressed complexly and have poor reliability due to the reasons of abrupt rigidity change, good construction quality and the like, and are usually weak areas of the structure, and the connection of the steel structure nodes mainly has the following forms: all-welded connections, bolted connections, and hybrid bolted connections. In view of labor costs and assembly requirements, the latter two are now commonly used in most countries, especially for stud-and-weld hybrid connections. However, the seismograph of the 1994 northern seismic showed that: theoretically, the bolted-welded hybrid connection steel joint with good ductility does not show expected ductility failure performance, but a brittle failure mode caused by cracks occurs at a flange weld joint with quality difficult to guarantee, so that great repair difficulty is caused. This is one of the reasons that structural researchers develop new types of nodes. On the other hand, earthquake damage investigation finds that although some steel nodes exert the advantage of ductility energy consumption, large permanent deformation remains due to accumulated plastic deformation after earthquake, so that the period and difficulty of structure repair are greatly increased, and the possibility of dismantling is sometimes encountered, thereby causing huge economic loss.

In order to improve the seismic performance of the node and ensure the ductility and energy consumption of the node, an engineer can strengthen the connecting part of the node, such as an haunching plate, or weaken the beam flange of a adjoined area, so that the plastic deformation of the structure is concentrated on a target part, and the requirement of a 'strong node' is ensured. In fact, the reinforcement or weakening is a balance of relative strength without altering the force transfer mechanism at the structural nodes (the beam upper and lower flanges form a couple that contributes most of the bending resistance and the web transfers most of the shear). Although this is advantageous for achieving life safety-based seismic requirements, from the full life cycle of the building structure, excessive residual deformation under moderate to high earthquakes inevitably makes such nodes unattractive.

Furthermore, another new type of node arises from the concurrent strengthening and weakening of the node strength method, i.e., a node that can recover performance. The node capable of recovering the function is also called a self-reset node, not only meets the design requirements of structural strength, rigidity and ductility energy consumption, but also can reset automatically after being unloaded, thereby greatly reducing or even eliminating the residual deformation of the structure. The node essentially separates the energy consumption behavior of the structure from the main structural components of the structure by changing the force transmission mechanism of the node, and the energy consumption behavior is borne by a specific energy consumption device which is easy to replace or is not replaced, and the node is assisted with a reset element to realize reset. The self-reset node consumes energy by replacing the structural plastic hinge with the supplemented energy consumption element, reduces the energy consumption capability of the structure to a certain extent, but can greatly improve the restorability of the structure, and can achieve organic unification of energy consumption and resettability through reasonable design. At present, there are two main methods for realizing the recoverable node, namely, a Post-tensioned prestressed rib (PT) type node adopting a PT pretensioning machine and an intelligent material with self-resetting performance used at the node. The prestress level of a high-strength steel rod in the PT node needs to be combined with an auxiliary energy dissipater according to the requirement based on a performance target, but the initial higher prestress level can increase the anchoring requirement, and meanwhile, the possibility of failure of the node under a strong earthquake is improved, and the failure is often fatal under the extremely rare conditions. With the innovation of metallurgical technology, the cost of the ultra-high performance Alloy is greatly reduced, and more intelligent materials begin to expand to the field of structural engineering, such as Shape Memory Alloy (SMA for short). The intelligent material has good shape memory effect and superelasticity performance, the former means that the intelligent material can recover the original shape by heating when being unloaded after being deformed under the action of a load, and the latter means that the material can automatically recover the original shape after being deformed under the action of the load after being unloaded, so that the intelligent material has the potential of self-reset in a structure, and simultaneously, because the material can automatically reset, the elastic energy released in the unloading process is much, and the energy really dissipated is much less than that of steel, so that the deformation can be recovered after an earthquake, but the energy consumption is insufficient, and the acceleration response of the structure under the action of an earthquake can be further increased.

In addition, although such a smart material has good restorability, the austenite elastic modulus (for example, NITI memory alloy) is about one third of that of steel. Therefore, when only the SMA bar is used as a reset and energy consumption element of the node, the strength, the rigidity and the energy consumption of the node are limited, and if other energy consumption mechanisms (such as friction and angle steel) are introduced to improve the behavior of the node, whether the restoring force stored in the node can effectively reset the node needs to be strictly examined.

The invention content is as follows:

the invention aims to effectively exert the advantages of various materials through technical innovation, further achieve the aim of improving the defects of the conventional node, and finally provide a feasible multi-stage energy consumption post-tensioning self-resetting node based on SMA damping and friction mechanisms by controlling energy consumption time sequences.

Aiming at the respective advantages and disadvantages of the two types of self-reset nodes, the two node technologies are combined to supplement each other, so that higher node performance (such as energy consumption and rigidity) is realized. The post-tensioning self-resetting node based on the multi-stage energy consumption of the SMA damping and friction mechanism solves the problems of anchoring difficulty and sharp reduction of the rotational rigidity of the unloaded node caused by the higher initial prestress level of the post-tensioning node due to the guarantee of recoverability; the problem of SMA node because initial rigidity is less, the power consumption is not enough, has caused under the earthquake, and displacement between the layer and the great demand of acceleration between the layer is solved. The novel node is designed based on performance, so that the design concept of the node is clearer, and the load (such as wind load) under normal use is resisted through the friction of the low-prestress steel bar, the T-shaped part web plate and the steel beam end reinforcing plate (filling plate) and the energy input into a system in a medium-small earthquake range is stably dissipated. Meanwhile, the SMA bar damping in the austenite working range can optimize the phenomenon of sharp rigidity reduction after the PT node is disconnected, so that the deformation of the node is controlled. When the node is under a medium or large earthquake, the SMA bar enters a phase transformation process of transforming from austenite to martensite, the rigidity of the node is reduced again, which is beneficial to reducing the local damage of the main component (ensuring that the main component is maintained in an elastic state). In addition, the node can recover automatically after being unloaded, and any element does not need to be replaced, so that the repair-free function is realized. In the aspect of node design, in order to resist the rare operating mode that meets, the slotted hole size of girder steel has rationally designed for the high strength bolt pole can extrude the pore wall at this operating mode, exerts the bearing capacity of girder steel, thereby has overcome traditional PT node because prestressing force steel bar inefficacy node completely became invalid thereupon under rare operating mode thereupon not enough, has increased the redundancy of node.

In order to achieve the purpose, the invention provides the following technical scheme:

a multi-stage energy-consuming post-tensioning self-resetting node comprises a steel column 1, a T-shaped connecting piece 4, an SMA bar damper 6, a post-tensioning prestressed steel bar 9 and a steel beam 8, and is characterized in that the steel beam 8 is installed on one side of a flange of the steel column 1, a long round bolt hole 8-1 is formed in the end portion of the steel beam 8, and the T-shaped connecting piece 4 is installed on the upper side and the lower side of the end portion of the steel beam 8; the high-strength first bolt 5-1 penetrates through the long round bolt hole 8-1 to fix the T-shaped connecting piece 4 and the steel beam 8; the T-shaped connecting piece 4 is connected with the flange of the steel column 1; an anchoring device 7 is further fixed on the steel beam 8; one end of the SMA bar damper 6 is connected with the T-shaped connecting piece 4, and the other end is connected with the anchoring device 7; and the post-tensioning prestressed steel bars 9 penetrate through the steel column 1 and the steel beam 6, are symmetrically arranged on two sides of the axis of the steel beam 6, and are anchored at the outer flange of the steel column 1 and the stiffening ribs 13 at the end part of the steel beam 8 through anchorage devices 11.

In a further improvement, a T-shaped part enlarged end 4-2 is formed at the upper and lower bulges of the end part of the middle web plate of the T-shaped connecting piece 4, and a tapping screw hole 4-3 is embedded in the T-shaped part enlarged end 4-2; the anchoring means 7 comprises a body portion and a cover portion 7-2; the main body part is fixedly connected with the steel beam 8; the main body part and the cover plate part 7-2 are covered to form a circular table type hole 7-3, and the main body part and the cover plate part 7-2 are fixed through a screw 7-1; one end of the SMA bar damper 6 is fixed with the tapping screw hole 4-3 through threads, and the other end of the SMA bar damper is fixed with the circular table type hole 7-3.

In a further improvement, the SMA bar damper 6 comprises a working section 6-1, and two ends of the working section 6-1 are respectively connected with a thread amplification end 4-2 matched with the tapping screw hole 4-3 and a truncated cone type amplification end 6-3 matched with the truncated cone type hole 7-3 through transition sections 6-3.

In a further improvement, a round hole 8-2 is formed in the steel beam 8, and a third bolt 5-3 penetrates through the round hole 8-2 to connect the anchoring device 7 with the steel beam 8.

In a further improvement, transverse short ribs 10 are welded at stiffening ribs 13 at the end part of the steel beam 8.

In a further improvement, a filling plate 12 is arranged between a web plate of the T-shaped connecting piece 4 and the steel beam 8; the contact surfaces of the web plate of the T-shaped connecting piece 4 and the filling plate 12 are both formed with rough layers.

The further improvement is that the steel column 1 is an I-shaped steel column; the steel beam 8 is an I-shaped steel beam; the T-shaped part consists of a flange, a web 4-1 and an enlarged end 4-2 of the T-shaped part; the first bolt 5-1, the second bolt 5-2 and the third bolt 5-3 are all friction high-strength bolts; the steel column is provided with a transverse stiffening rib 2 and a reinforcing plate 3 for anchoring a prestressed steel bar.

In a further improvement, when the node corner is 5%, the first bolt 5-1 is in contact with the hole wall of the long round bolt hole 8-1, namely the radial distance between the circle center of the high-strength first bolt 5-1 and the hole wall of the long round bolt hole 8-1 is the product of the height h of the beam multiplied by 5% plus the radius of the first bolt 5-1.

A multi-stage energy-consuming post-tensioning self-resetting node assembling method comprises the following steps:

the method comprises the following steps: the method comprises the following steps of producing a steel column 1, a steel beam 8, a T-shaped connecting piece 4 with a thread enlarged end 4-2, an SMA bar damper 6, an anchoring device 7, a post-tensioning prestressed steel bar 9, corresponding beam column tightening ribs and an anchoring plate in a factory in a standardized manner; bolt holes are formed in corresponding parts of the steel beam 8, the steel column 1, the T-shaped connecting piece 4, the anchoring device 7 and the filling plate 12; welding stiffening ribs 13 and reinforcing plates 3 on corresponding parts of the steel columns 1 and the steel beams 8;

step two: installing and positioning a steel beam 8, a steel column 1 and a T-shaped connecting piece 4 with a thread enlarged end 4-2 through bolts, and screwing the bolts;

step three: one end of an SMA bar damper 6 is installed and screwed at an amplifying end 4-2 of the T-shaped part, the other end of the SMA bar damper 6 is connected with an anchoring device 7, the anchoring device 7 is fixed at a preset position of a steel beam 8 through bolts, a second bolt 5-2 for fixing the steel beam 8 and the T-shaped connecting part 4 and a third bolt 5-3 for fixing the anchoring device 7 and the steel beam 8 apply half of a target pretightening force firstly, a web plate (4-1) of the T-shaped connecting part 4 and the steel beam 8 are pressed and the anchoring device 7 are pressed, and in addition, the first bolt 5-1 is manually screwed and positioned; secondly, applying prestress of a post-tensioning prestress steel bar 9 through a hydraulic jack, and pressing a flange of the steel column 1 and a steel beam 8; and finally, applying the first bolt 5-1, the second bolt 5-2 and the third bolt 5-3 to target pretightening force to complete assembly.

The invention has the following benefits:

1. the invention combines the advantages of the PT node and the SMA node, and realizes higher node performance (such as energy consumption and rigidity). The post-tensioning self-resetting node based on the multi-stage energy consumption of the SMA damping and friction mechanism solves the problems of anchoring difficulty and sharp reduction of the rotational rigidity after the node is disconnected, which are caused by the higher initial prestress level of the post-tensioning node due to the guarantee of recoverability; the problem that interlayer displacement and interlayer acceleration requirements are high under an earthquake due to the fact that the SMA node is low in initial rigidity and insufficient in energy consumption is solved; the node still has the functions of self-resetting and repair-free under the condition of large earthquake.

2. The invention is based on performance design, simultaneously reasonably arranges the working time sequences of two types of damping mechanisms, so that the node performance is more flexible and adjustable, and the initial stress level (applied initial strength/steel bar yield strength) of the prestressed steel bar can be reduced to 0.1 due to the introduction of the SMA damper and the friction damping of a medium-low level, thereby greatly reducing the anchoring difficulty of the prestressed steel bar and improving the anchoring reliability. The slightly tensioned PT node is matched with the low-friction damping to resist loads (such as wind loads) under normal use and dissipate energy within a low-medium shock range, and the SMA damper only contributes certain node rotational rigidity in the process, so that the adverse condition that the rigidity is sharply reduced after the node is disconnected is optimized, and almost no energy consumption is provided. Along with the increase of earthquake motion, the SMA damping enters a phase change stage, the node immediately enters a combined energy consumption mode, meanwhile, the rotational stiffness of the node is further reduced to reduce the damage of the main component beam column, and the node can be completely reset after the earthquake.

3. The invention has convenient installation, and the performance can be adjusted by changing the pretightening force of the high-strength bolt and the size of the SMA bar so as to adapt to different earthquake-resistant areas and the requirements of owners.

4. The node provided by the invention is completely symmetrical about a neutral axis, so that the performance of the node under the action of positive and negative bending moments is consistent, taking the positive bending moment as an example, under the action of the positive bending moment, the lower flange of the beam, which is in contact with a T-shaped piece, is gradually decompressed, the upper flange of the beam is gradually boosted, the bending resistance of the node is provided in a force transmission mode until the lower flange of the beam is completely decompressed, then the lower flange of the beam enters a static friction stage between the lower flange of the beam and the T-shaped piece, further, the beam and the T-shaped piece rotate relatively, SMA bar damping generates elastic elongation deformation, SMA bar damping enters phase change energy consumption along with continuous loading, and at the moment, the node can be completely reset after being unloaded, and a main component beam column is in an elastic working range, and the friction and the SMA damping.

5. The node adopts the NITI intelligent alloy with shape memory with moderate elastic modulus, and has two-stage benefits: firstly, under medium and small earthquakes, the mechanical property of the disconnected sections can be improved (the rotational rigidity of the joints is increased, and the elastic deformation is relied on), so that the lateral deformation of the structure is controlled, and the non-structural members sensitive to the interlayer lateral movement are protected, and secondly, under medium and large earthquakes, the phase change energy consumption behavior of the non-structural members is activated, and the non-structural members serve as supplementary damping and friction damping to form composite damping to achieve the purpose of fully dissipating the system energy, and meanwhile, along with the reduction of the rigidity of the joints, the main members (beams and columns) are favorably maintained in an elastic state, and the local damage of the bearing. In addition, after the earthquake of medium and large magnitude, the SMA damping is automatically reset, namely the additional damping does not increase the requirement of the steel strand, and the node can be restored to a nondestructive state without repairing.

6. According to the design, the size of the long round hole is reasonably designed, the condition that the hole wall and the bolt rod are allowed to bear pressure after the corner of the node exceeds 5% is considered, namely the node is converted into a pressure-bearing type node (the ultimate bearing capacity of the beam is exerted and is consistent with the stress of the traditional node), the structure is prevented from completely failing, and the multi-redundancy characteristic is presented.

Description of the drawings:

FIG. 1 is a schematic illustration of the position of the present invention in a structure;

FIG. 2-1 is a schematic view of the overall three-dimensional structure of the node of the present invention;

FIG. 2-2 is a schematic perspective view of a T-shaped connector;

FIGS. 2-3 are schematic perspective views of the anchoring device;

FIG. 3 is a schematic view of node disassembly;

FIG. 4 is a front view of the present invention;

FIG. 5 is a side view of the present invention;

FIG. 6 is a top view of the present invention;

FIG. 7 is a schematic view of an I-beam with bolt holes;

FIG. 8 is a schematic representation of SMA bar.

FIG. 9 is a schematic view of a prestressed steel bar and cylindrical anchor

Wherein, the numbering of each part is: 1. a steel column; 2. a column transverse stiffener; 3. a reinforcing plate; 4. a T-shaped connector; 4-1, a tee web; 4-2, a thread enlarging end; 4-3, tapping screw holes; 5-1, a first bolt; 5-2, a second bolt; 5-3, a third bolt; 6. an SMA bar damper; 6-1, a working section; 6-2, a thread enlarging end; 6-3, a truncated cone type amplification end; 6-4, a transition section; 7. an anchoring device; 7-1, screws; 7-2, a cover plate part; 7-3, a circular truncated cone type hole; 7-4, installing screw holes on the SMA installation device; 8. a steel beam; 9. post-tensioning the prestressed steel bar; 10. a transverse short rib; 11. an anchorage device; 12. filling a plate; 13. a stiffening rib.

The specific implementation mode is as follows:

in order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is made with reference to the accompanying drawings and specific embodiments.

The invention provides a post-tensioning self-resetting node based on an SMA damping device and friction multi-stage energy consumption, which comprises: the steel structure comprises I-shaped steel columns, I-shaped steel beams, T-shaped connecting pieces with enlarged ends, SMA bar dampers, prestressed steel rods, anchors, seven reinforcing plates at the anchoring positions of the outer flanges of the columns, eight transverse column reinforcing ribs, nine beam anchoring end plates and end reinforcing ribs, ten beam flange end plate reinforcing plates, and high-strength friction bolts.

The self-resetting node is taken from a beam-column node selected in a structure, and comprises the structural components described above, wherein the reinforcing plate at the column anchoring part is welded at the outer flange of the column by adopting a four-sided angle, the transverse stiffening rib of the column is welded at the node area of the I-shaped steel column by adopting a three-sided angle, and the beam-end anchoring end plate, the short rib and the beam-end flange reinforcing plate are welded at the preset position by adopting an angle welding mode.

Positioning the flange of the I-shaped steel beam and the flange of the steel column with the T-shaped part, installing bolts, further installing an SMA bar damper, initially screwing all the bolts, installing a prestressed steel bar, applying a target value exceeding the pre-tightening force, continuing for a period of time, returning oil, observing the rebound of a prestressed anchoring part, iterating for several times to the target value of the pre-tightening force, and finally screwing all the friction type high-strength bolts to a preset value. Wherein the web of the tee acts both as a friction plate and transfers nodal shear. In the stress process of the node, main components of the beam column are in an elastic range, and energy is dissipated through friction and SMA damping, but energy dissipation mechanisms can be repeatedly used, so that any repair is not needed in the preset performance. The assembly method of the post-tensioning self-resetting node based on the SMA damping device and the friction multi-stage energy consumption comprises the following steps:

1. after the components are produced in a corresponding factory standard mode, pre-positioning is carried out on a factory assembly line, holes are formed in the I-shaped steel column, the steel beam, the T-shaped part and each anchoring and reinforcing plate, and the stiffening ribs and the reinforcing plates are welded to the preset positions of the steel column and the steel beam; after the SMA bar is formed, heat treatment is needed, and then threads are machined; the enlarged end of the T-shaped piece needs to be drilled and tapped to connect the SMA bar damper; SMA damping anchor mounting devices require drilling and cutting.

2. The flanges of the tee are bolted to the column flange preset locations. And after the connection is finished, the bolts are transported to the site to finish the connection of all the components, and all the bolts are initially screwed.

3. And tensioning the prestressed steel bar, and screwing all the bolts to a target torque after tensioning.

Compared with the traditional node, the node has the following innovation: (1) the SMA bar damping is separated from the node shearing resistance mechanism and used as a damping force to improve the rotational rigidity of the node after disconnection under medium and small earthquakes, and the energy consumption behavior of the structure is enhanced under medium and large earthquakes, so that the functions are more definite. (2) Because the SMA bar damping is introduced, the node energy consumption behavior is improved without increasing the resetting burden of the node, and the rigidity of the disconnected node is improved, so that the initial prestress level of the high-strength steel rod can be greatly reduced, the anchoring reliability is improved, and the anchoring difficulty is reduced. (3) The node separates the energy consumption behavior from the main components and has friction and SMA phase change to bear, and the mechanisms can be used for infinite times without replacement and repair and almost completely reset under the restoring force of the prestressed steel bars. (4) Compared with a PT node, the novel node realizes the same initial rigidity by using a smaller prestress level, greatly improves the unloading rigidity of the node after the node is separated, and is favorable for controlling the interlayer deformation of the structure under medium and small earthquakes. (5) Compared with the SMA bar self-reset node, the initial rigidity of the node is greatly improved, and the unfavorable condition that the SMA bar is in shearing is avoided. (6) The novel node realizes multi-stage energy consumption by reasonably arranging energy consumption time sequences of two energy consumption mechanisms, and further optimizes the node performance. (7) All the installation operations can be assembled, and the construction period is shortened.

The node of the invention is essentially effective combination of two self-reset nodes, and adjusts the working time sequence of an energy consumption mechanism to further realize the anti-seismic requirements under different stages, for example, the node needs to strictly control the deformation between layers to avoid the damage of non-structural components under medium and small earthquakes, so the rotational rigidity of the node after unloading can not be reduced too much but can not be too flexible, and the SMA bar damper can flexibly adjust the rigidity of the node at the stage. When the structure is subjected to strong earthquake, the key of reducing the repair difficulty and period after the earthquake is to ensure that main components are not damaged, so that the main structure is weakened, the SMA damping enters a phase change energy consumption stage, the main structure can be reset by virtue of the reset element after the earthquake, and the main structure does not need to be repaired, so that the invention has higher comprehensive economic benefit in the whole life cycle of the structure.

The foregoing is merely a specific example of the present invention, and it is within the scope of the invention to cover such modifications and substitutions as may be made without departing from the spirit and scope of the invention.

Claims

1. A multi-stage energy-consuming post-tensioning self-resetting node comprises a steel column (1), a T-shaped connecting piece (4), an SMA bar damper (6), a post-tensioning pre-stress steel bar (9) and a steel beam (8), and is characterized in that the steel beam (8) is installed on one side of a flange of the steel column (1), a long round bolt hole (8-1) is formed in the end portion of the steel beam (8), and the T-shaped connecting piece (4) is installed on the upper side and the lower side of the end portion of the steel beam (8); the high-strength first bolt (5-1) penetrates through the long round bolt hole (8-1) to fix the T-shaped connecting piece (4) and the steel beam (8); the T-shaped connecting piece (4) is connected with the flange of the steel column (1); an anchoring device (7) is further fixed on the steel beam (8); one end of the SMA bar damper (6) is connected with the T-shaped connecting piece (4), and the other end is connected with the anchoring device (7); the post-tensioning prestressed steel bar (9) penetrates through the steel column (1) and the steel beam (6) and is symmetrically arranged on two sides of the axis of the steel beam (6) and anchored at the outer flange of the steel column (1) and a stiffening rib (13) at the end part of the steel beam (8) through an anchorage device (11).

2. The multi-stage energy-consuming post-tensioning self-resetting node is characterized in that a T-shaped enlarged end (4-2) is formed at the end part of the middle web plate of the T-shaped connecting piece (4) in a protruding mode, and a tapping screw hole (4-3) is embedded in the T-shaped enlarged end (4-2); the anchoring device (7) comprises a body portion and a cover portion (7-2); the main body part is fixedly connected with a steel beam (8); the main body part and the cover plate part (7-2) are covered to form a circular table type hole (7-3), and the main body part and the cover plate part (7-2) are fixed through a screw (7-1); one end of the SMA bar damper (6) is fixed with the tapping screw hole (4-3) in a threaded manner, and the other end of the SMA bar damper is fixed with the circular truncated cone-shaped hole (7-3).

3. The multi-stage energy-consuming post-tensioning self-resetting node as claimed in claim 2, wherein the SMA bar damper (6) comprises a working section (6-1), and a thread enlarged end (4-2) matched with the tapping screw hole (4-3) and a truncated cone enlarged end (6-3) matched with the truncated cone hole (7-3) are respectively connected to two ends of the working section (6-1) through a transition section (6-3).

4. A multi-stage energy consuming post-tensioned self-resetting joint as claimed in claim 2, characterised in that the steel beam (8) is formed with a circular hole (8-2) and a third bolt (5-3) is passed through the circular hole (8-2) to connect the anchoring device (7) to the steel beam (8).

5. A multi-stage energy consuming post-tensioned self-resetting node according to claim 1, characterised in that transverse short ribs (10) are welded at the steel beam (8) end stiffeners (13).

6. A multi-stage energy consuming post-tensioned self-resetting joint as claimed in claim 1, characterised in that a filler plate (12) is mounted between the web of the T-connector (4) and the steel beam (8); the contact surfaces of the web plate of the T-shaped connecting piece (4) and the filling plate (12) are both formed with rough layers.

7. A multi-stage energy consuming post-tensioned self-resetting node according to claim 1, characterised in that the steel columns (1) are i-shaped steel columns; the steel beam (8) is an I-shaped steel beam; the T-shaped part consists of a flange, a web (4-1) and an enlarged end (4-2) of the T-shaped part; the first bolt (5-1), the second bolt (5-2) and the third bolt (5-3) are all friction high-strength bolts; the steel column is provided with a transverse stiffening rib (2) and a reinforcing plate (3) for anchoring a prestressed steel bar.

8. A multi-stage energy consuming post-tensioned self-resetting joint as claimed in claim 1, characterised in that at a 5% turn of the joint the first bolt (5-1) is in contact with the wall of the oblong bolt hole (8-1), i.e. the radial distance between the centre of the high-strength first bolt (5-1) and the wall of the oblong bolt hole (8-1) is the product of the beam height h times 5% plus the radius of the first bolt (5-1).

9. The assembling method of the multi-stage energy-consuming post-tensioning self-resetting node is characterized by comprising the following steps of:

the method comprises the following steps: the method comprises the following steps of producing a steel column (1), a steel beam (8), a T-shaped connecting piece (4) with a thread enlarged end (4-2), an SMA bar damper (6), an anchoring device (7), a post-tensioning prestressed steel bar (9), corresponding beam column tightening ribs and an anchoring plate in a factory in a standardized manner; bolt holes are formed in corresponding parts of the steel beam (8), the steel column (1), the T-shaped connecting piece (4), the anchoring device (7) and the filling plate (12); welding stiffening ribs (13) and reinforcing plates (3) on corresponding parts of the steel columns (1) and the steel beams (8);

step two: installing and positioning a steel beam (8), a steel column (1) and a T-shaped connecting piece (4) with a thread enlarged end (4-2) through bolts, and screwing the bolts;

step three: one end of an SMA bar damper (6) is installed and screwed at an enlarged end (4-2) of a T-shaped part, the other end of the SMA bar damper (6) is connected with an anchoring device (7), the anchoring device (7) is fixed at a preset position of a steel beam (8) through bolts, a second bolt (5-2) for fixing the steel beam (8) and a T-shaped connecting piece (4) and a third bolt (5-3) for fixing the anchoring device (7) and the steel beam (8) apply half of a target pretightening force firstly, a web plate (4-1) and the steel beam (8) of the T-shaped connecting piece (4) are pressed and the anchoring device (7) are pressed, and the first bolt (5-1) is manually screwed and positioned; secondly, applying prestress of a post-tensioning prestress steel bar (9) through a hydraulic jack, and pressing a flange of the steel column (1) and the steel beam (8); and finally, applying the first bolt (5-1), the second bolt (5-2) and the third bolt (5-3) to the target pretightening force, and finishing the assembly.