Post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation

Abstract

The present invention discloses a post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation, which includes a steel column (1), a bracket (2), a steel beam (3), a web connection plate (41), a lower flange connection plate, and a mild steel damper (6); the bracket is installed on the steel column, and the upper flange (21) of the bracket is butt-jointed and fixed with the upper flange (31) of the steel beam; the web (22) of the bracket is slidably connected to the web (32) of the steel beam through the web connection plate, and the lower flange (23) of the bracket is slidably connected to the lower flange (33) of the steel beam through the lower flange connection plate; when the bracket is butt-jointed with the steel beam, the mild steel damper is inserted and bite-connected between the lower flange of the bracket and the lower flange of the steel beam, and the mild steel damper is slidably connected to the lower flange connection plate. The present invention can ensure that the beam-column connection joint is a fully rigid connection under static conditions and small earthquake actions, dissipates energy and reduces vibration under medium and large earthquake actions, is convenient for installation and post-earthquake repair, and does not occupy the clear height of the beam bottom.

Description

Technical Field

[0001] The present invention relates to a steel structure beam-column connection node, and particularly to a post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and dual energy dissipation. Background Art

[0002] The energy dissipation and seismic reduction structure refers to a structure in which energy dissipation and seismic reduction devices are installed in a building. The existing energy dissipation and seismic reduction devices include metallic mild steel dampers, friction dampers, viscous dampers, etc. The seismic energy input into the structure is dissipated by the relative deformation work of the energy dissipation and seismic reduction devices to meet the expected energy dissipation and seismic reduction requirements.

[0003] At present, the beam-column connection nodes of the existing seismic steel frame structures usually adopt the bolt-welding connection with a bracket. The flange of the bracket and the steel beam is connected by butt welding, and the web is connected by high-strength bolts. And a flange weakening section is set at the beam end to form a plastic hinge under medium and large earthquakes to meet the requirement of strong columns and weak beams.

[0004] The advantages of the existing beam-column node connection method are convenient installation. During construction, the web bolts are first positioned, and then the butt welding of the upper and lower flanges is carried out. Its disadvantages are that the plastic hinge at the beam end dissipates energy under medium and large earthquakes, which is not conducive to post-earthquake repair, and the energy dissipation capacity of the plastic hinge at the beam end is limited.

[0005] Chinese Invention Patent (CN111851757A) discloses a steel structure beam-column connection node with a metallic round bar energy dissipation damper, and Chinese Invention Patent (CN112832400A) discloses a friction energy dissipation type damper and a steel frame beam-column connection node. The above two invention patents can both meet the energy dissipation of the beam-column connection node through the additional damper under earthquake action, and the damper is easy to replace after damage. However, in order to give play to the role of the damper, a certain amount of slip needs to be allowed between the lower flange of the steel beam and the steel column, resulting in a non-fully rigid connection of the beam-column connection node, and its rotational stiffness is related to the characteristics of the damper, showing a non-linear characteristic, which brings great difficulties to the design and analysis in practical applications. In addition, the installed damper needs to occupy the space at the bottom of the beam, which is not applicable to buildings with high requirements for the net height of the building, and the installation of the damper at the bottom of the beam also has a greater impact on the aesthetic appearance of the ceiling.

[0006] Therefore, it is necessary to provide a beam-column connection node form that combines rigid connection, energy dissipation, replaceability after damage, convenient installation and does not occupy the net height at the bottom of the beam. Summary of the Invention

[0007] The purpose of the present invention is to provide a post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and dual energy dissipation, which can ensure that the beam-column connection node is a fully rigid connection under static conditions and small earthquakes, dissipates energy and reduces seismic effects under medium and large earthquakes, is convenient for installation and post-earthquake repair, and does not occupy the net height at the bottom of the beam.

[0008] The present invention is implemented as follows:

[0009] A post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation includes a steel column, a bracket, a steel beam, a web connection plate, a lower flange connection plate and a mild steel damper; one end of the bracket is installed on the steel column, and the upper flange of the bracket at the other end of the bracket is butted and fixed with the upper flange of the steel beam at one end of the steel beam; the web of the bracket at the other end of the bracket is slidably connected to the web of the steel beam at one end of the steel beam through the web connection plate, and the lower flange of the bracket at the other end of the bracket is slidably connected to the lower flange of the steel beam at one end of the steel beam through the lower flange connection plate; the length of the lower flange of the bracket is less than the length of the web of the bracket, and the length of the lower flange of the steel beam is less than the length of the web of the steel beam, so that when the bracket is butted with the steel beam, the mild steel damper can be arranged between the lower flange of the bracket and the lower flange of the steel beam, and the mild steel damper is slidably connected to the lower flange connection plate.

[0010] A plurality of web bolt holes are opened at the other end of the web of the bracket and one end of the web of the steel beam, and a plurality of first oblong holes are opened on the web connection plate, so that the web bolts can penetrate through the web bolt holes and the first oblong holes, and the web of the bracket can be slidably connected to the web of the steel beam through the web connection plate via the first oblong holes; the length direction of the first oblong holes is parallel to the length direction of the steel beam; there are two web connection plates, and the two web connection plates are symmetrically arranged on both sides of the web of the bracket and the web of the steel beam.

[0011] The length of the web of the bracket is less than the length of the upper flange of the bracket, and the length of the web of the steel beam is less than the length of the upper flange of the steel beam, so that after the upper flange of the bracket is butted with the upper flange of the steel beam, a gap is formed between the web of the bracket and the web of the steel beam, and the width of the gap is greater than the relative displacement amount of the web of the steel beam and the web of the bracket under a major earthquake.

[0012] A plurality of lower flange bolt holes are opened at the other end of the lower flange of the bracket and one end of the lower flange of the steel beam, and a plurality of second oblong holes are opened on the lower flange connection plate, so that the lower flange bolts can penetrate through the lower flange bolt holes and the second oblong holes, and the lower flange of the bracket can be slidably connected to the lower flange of the steel beam through the lower flange connection plate via the second oblong holes; the length direction of the second oblong holes is parallel to the length direction of the steel beam.

[0013] The described lower flange connecting plate includes a first lower flange connecting plate and a second lower flange connecting plate; a pair of first lower flange connecting plates are respectively arranged on the top surfaces of the bracket lower flange and the steel beam lower flange and are symmetrically located on both sides of the bracket web and the steel beam web. A first friction surface is formed between the bottom surfaces of the pair of first lower flange connecting plates and the top surfaces of the bracket lower flange and the steel beam lower flange; the second lower flange connecting plate is arranged under the bottom surfaces of the bracket lower flange and the steel beam lower flange, and a second friction surface is formed between the top surface of the second lower flange connecting plate and the bottom surfaces of the bracket lower flange and the steel beam lower flange; the starting slip internal force between the bracket lower flange and the lower flange connecting plate and between the steel beam lower flange and the lower flange connecting plate is greater than the internal force design value of the steel beam lower flange under the static condition and the action of a minor earthquake.

[0014] The described mild steel damper includes a damper core material and damper connecting heads. A pair of damper connecting heads are respectively symmetrically arranged at both ends of the damper core material, and the pair of damper connecting heads are respectively connected with the steel beam lower flange and the bracket lower flange in an inserted and engaged manner.

[0015] Wedge-shaped slots are opened at the other end of the bracket lower flange and one end of the steel beam lower flange. The end of the damper connecting head is formed with a wedge-shaped insert strip, and the wedge-shaped insert strip can be inserted into the wedge-shaped slot in a matching manner, so that the damper connecting head is connected with the steel beam lower flange and the bracket lower flange in an inserted and engaged manner; the wedge-shaped insert strip is welded to the damper core material, and the tensile bearing capacity of its weld and the axial tensile and compressive bearing capacities at the weakest section of the cross-section of the wedge-shaped slot and the wedge-shaped insert strip should be greater than the ultimate axial internal force design value of the mild steel damper under the action of a major earthquake.

[0016] A number of third oblong holes are opened on the damper core material, and a number of damper bolt holes are opened on the lower flange connecting plate. The length direction of the third oblong holes is parallel to the length direction of the steel beam. The damper bolts can penetrate through the third oblong holes and the damper bolt holes, so that the damper core material is connected with the lower flange connecting plate in a slidable manner through the third oblong holes.

[0017] Partition plates are arranged on both the top surface and the bottom surface of the damper core material. A number of fourth oblong holes are opened on the partition plates, and the number of fourth oblong holes are respectively aligned with the number of third oblong holes. The partition plates are connected and fixed with the mild steel damper, the first lower flange connecting plate, and the second lower flange connecting plate through damper bolts.

[0018] The total thickness of the damper core material and the upper and lower two partition plates is equal to the thickness of the bracket lower flange and the thickness of the steel beam lower flange.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. Since the present invention is provided with a web connection plate with a first oblong hole and a lower flange connection plate with a second oblong hole, the web connection plate, the bracket web and the steel beam web are locked by web bolts, and the lower flange connection plate, the bracket lower flange and the steel beam lower flange are locked by lower flange bolts. Under static conditions or minor earthquake actions, the internal force of the lower flange is completely borne and transmitted by the friction between the plates without slippage, providing sufficient stiffness for the structure and ensuring the rigid connection characteristics of the beam-column connection node, thus ensuring that the steel frame has sufficient lateral stiffness resistance.

[0021] 2. Since the present invention is provided with a mild steel damper, under medium and major earthquake actions, when the internal force between the bracket lower flange and the steel beam lower flange exceeds the friction resistance limit between the plates, a relative displacement occurs between the steel beam lower flange and the bracket lower flange, and the friction between the bracket lower flange, the steel beam lower flange and the lower flange connection plate does work to consume seismic energy. At the same time, the mild steel damper deforms accordingly, further consuming seismic energy, thereby achieving double energy dissipation and improving the energy dissipation capacity of the node under earthquake actions.

[0022] 3. Since the present invention is provided with a mild steel damper, the plastic deformation of the beam-column node is concentrated on the mild steel damper, ensuring that the beam of the main structure does not suffer damage under earthquake actions. The two ends of the damper core are matched and inserted into the wedge-shaped slots of the bracket lower flange and the steel beam lower flange through the wedge-shaped inserts of the damper connector, which is convenient for disassembly and assembly and easy to repair after an earthquake.

[0023] 4. Since the present invention sets the mild steel damper between the bracket lower flange and the steel beam lower flange within the flange height range, it does not occupy the clear height at the bottom of the beam, and the bottom of the beam is flat and beautiful. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a three-dimensional view of the post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and double energy dissipation of the present invention;

[0025] Figure 2 is Figure 1 an enlarged schematic view of part A in

[0026] Figure 3 is an exploded view of the post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and double energy dissipation of the present invention;

[0027] Figure 4 is an exploded view of the mild steel damper and the partition in the post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and double energy dissipation of the present invention;

[0028] Figure 5 is the front view of the post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and double energy dissipation of the present invention;

[0029] Figure 6 is Figure 5The sectional view taken along line a-a in;

[0030] Figure 7 is Figure 5 The sectional view taken along line b-b in;

[0031] Figure 8 is Figure 5 The sectional view taken along line c-c in.

[0032] In the figure, 1 is a steel column, 2 is a bracket, 21 is the upper flange of the bracket, 22 is the web of the bracket, 23 is the lower flange of the bracket, 3 is a steel beam, 31 is the upper flange of the steel beam, 32 is the web of the steel beam, 33 is the lower flange of the steel beam, 41 is a web connection plate, 42 is a web bolt, 43 is a first oblong hole, 44 is a web bolt hole, 51 is a first lower flange connection plate, 52 is a second lower flange connection plate, 53 is a lower flange bolt, 54 is a damper bolt, 55 is a lower flange bolt hole, 56 is a second oblong hole, 57 is a damper bolt hole, 6 is a mild steel damper, 61 is a damper core material, 62 is a damper connector, 63 is a wedge insert, 64 is a third oblong hole, 65 is a wedge slot, 7 is a diaphragm, 71 is a fourth oblong hole, 81 is a first friction surface, 82 is a second friction surface. Detailed implementation manners

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] Please refer to the attached Figure 1 to the attached Figure 3 , a post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation, including a steel column 1, a bracket 2, a steel beam 3, a web connection plate 41, a lower flange connection plate and a mild steel damper 6; one end of the bracket 2 is installed on the steel column 1, and the upper flange 21 of the bracket at the other end of the bracket 2 is butted and fixed with the upper flange 31 of the steel beam at one end of the steel beam 3; the web 22 of the bracket at the other end of the bracket 2 is slidably connected to the web 32 of the steel beam at one end of the steel beam 3 through the web connection plate 41, and the lower flange 23 of the bracket at the other end of the bracket 2 is slidably connected to the lower flange 33 of the steel beam at one end of the steel beam 3 through the lower flange connection plate; the length of the lower flange 23 of the bracket is less than the length of the web 22 of the bracket, and the length of the lower flange 33 of the steel beam is less than the length of the web 32 of the steel beam, so that when the bracket 2 is butted with the steel beam 3, the mild steel damper 6 can be arranged between the lower flange 23 of the bracket and the lower flange 33 of the steel beam, and the mild steel damper 6 is slidably connected to the lower flange connection plate.

[0035] A sliding connection is formed between the web connecting plate 41 and the corbel web 22 and the steel beam web 32, and a sliding connection is formed between the lower flange connecting plate and the corbel lower flange 23 and the steel beam lower flange 33, forming a multi-level defense structure, and the relative friction between the sliding surfaces is used to ensure the complete rigid connection of the beam-column connection node under static working conditions and small earthquakes. At the same time, the soft steel damper 6 adopts an inserted bite connection between the corbel lower flange 23 and the steel beam lower flange 33. During medium and large earthquakes, the corbel lower flange 23 and the steel beam lower flange 33 slide to do work, consume seismic energy, and cause the soft steel damper 6 to deform accordingly, further consume seismic energy, and achieve the purpose of energy dissipation and shock reduction.

[0036] Please see attached Figure 2 and attached Figure 4 The other end of the corbel web 22 and one end of the steel beam web 32 are both provided with a plurality of web bolt holes 44, and the web connecting plate 41 is provided with a plurality of first oblong holes 43, so that the web bolts 42 can pass through the web bolt holes 44 and the first oblong holes 43, and the corbel web 22 can be slidably connected to the steel beam web 32 through the web connecting plate 41 via the first oblong holes 43.

[0037] By utilizing the setting of the first oblong hole 43, while locking the web connecting plate 41, the steel beam web 32 and the corbel web 22, the sliding amount of the web bolt 42 during moderate and severe earthquakes does not exceed the allowable sliding length of the first oblong hole 43, thereby ensuring that the bolt hole wall is not squeezed and damaged, and the corbel web 22 and the steel beam web 32 can always slide freely with the corbel lower flange 23 and the steel beam lower flange 33.

[0038] The length direction of the first oblong hole 43 is parallel to the length direction of the steel beam 3, and the allowable slip length of the first oblong hole 43 is slightly larger than the slip amount of the web bolt 42 under a large earthquake. The length of the first oblong hole 43 can be calculated according to the seismic intensity of the project location.

[0039] Please see attached Figure 1 , Attachment Figure 3 and attached Figure 5 The length of the corbel web 22 is smaller than the length of the corbel upper flange 21, and the length of the steel beam web 32 is smaller than the length of the steel beam upper flange 31, so that after the corbel upper flange 21 is butted against the steel beam upper flange 31, a gap is formed between the corbel web 22 and the steel beam web 32, and the gap width is slightly larger than the relative displacement between the steel beam web 32 and the corbel web 22 under a large earthquake.

[0040] The gap between the corbel web 22 and the steel beam web 32 can be set to prevent the corbel web 22 and the steel beam web 32 from sliding relative to each other during moderate or severe earthquakes, thereby preventing the two from colliding and squeezing each other.

[0041] Please see attached Figure 3 and attachedFigure 6 There are two web connecting plates 41, which are symmetrically arranged on both sides of the bracket web 22 and the steel beam web 32 to form a double-shear connection.

[0042] Please refer to the appendix Figure 3 At the other end of the lower flange 23 of the bracket and one end of the lower flange 33 of the steel beam, a number of lower flange bolt holes 55 are opened. A number of second oblong holes 56 are opened on the lower flange connecting plate, so that the lower flange bolts 53 can pass through the lower flange bolt holes 55 and the second oblong holes 56, and the lower flange 23 of the bracket can be slidably connected to the lower flange 33 of the steel beam through the lower flange connecting plate via the second oblong holes 56.

[0043] By using the second oblong holes 56, when the lower flange connecting plate, the lower flange 33 of the steel beam and the lower flange 23 of the bracket are locked, the slip amount of the lower flange bolts 53 under medium and large earthquakes does not exceed the allowable slip length of the second oblong holes 56, so as to ensure that the bolt hole walls are not damaged by extrusion.

[0044] The length direction of the second oblong holes 56 is parallel to the length direction of the steel beam 3, and the length of the second oblong holes 56 is slightly larger than the slip amount of the lower flange bolts 53 under large earthquakes. The allowable slip length of the second oblong holes 56 can be calculated according to the fortification earthquake intensity of the project location.

[0045] Please refer to the appendix Figure 2 and the appendix Figure 3 and the appendix Figure 7 Please refer to the appendix

[0046] The lower flange connecting plate includes a first lower flange connecting plate 51 and a second lower flange connecting plate 52; a pair of first lower flange connecting plates 51 are respectively arranged on the top surfaces of the lower flange 23 of the bracket and the lower flange 33 of the steel beam and are symmetrically located on both sides of the bracket web 22 and the steel beam web 32. A first friction surface 81 is formed between the bottom surfaces of the pair of first lower flange connecting plates 51 and the top surfaces of the lower flange 23 of the bracket and the lower flange 33 of the steel beam; the second lower flange connecting plate 52 is arranged under the bottom surfaces of the lower flange 23 of the bracket and the lower flange 33 of the steel beam, and a second friction surface 82 is formed between the top surface of the second lower flange connecting plate 52 and the bottom surfaces of the lower flange 23 of the bracket and the lower flange 33 of the steel beam.

[0047] The friction coefficients between the first friction surface 81 and the second friction surface 82 need to be designed such that the starting slip internal forces between the lower flange 23 of the corbel, the first lower flange connecting plate 51, and the second lower flange connecting plate 52, as well as between the lower flange 33 of the steel beam, the first lower flange connecting plate 51, and the second lower flange connecting plate 52, are slightly greater than the internal force design value of the lower flange 33 of the steel beam under the static condition and the action of minor earthquakes. Under the action of moderate and major earthquakes, when the internal force design value of the lower flange 33 of the steel beam exceeds the above-mentioned starting slip internal force, relative displacement occurs between the lower flange 23 of the corbel and the lower flange 33 of the steel beam. The frictional forces on the first friction surface 81 and the second friction surface 82 do work and dissipate energy, and at the same time, the mild steel damper 6 undergoes axial deformation to dissipate energy.

[0048] Please refer to Appendix Figure 2 , Appendix Figure 4 and Appendix Figure 8 , the mild steel damper 6 includes a damper core 61 and damper connectors 62. A pair of damper connectors 62 are symmetrically arranged at both ends of the damper core 61, and a pair of damper connectors 62 are respectively inserted and bite-connected to the lower flange 33 of the steel beam and the lower flange 23 of the corbel.

[0049] The damper core 61 is inserted and bite-connected to the lower flange 23 of the corbel and the lower flange 33 of the steel beam through the damper connectors 62, which is convenient for disassembly and assembly. When the mild steel damper 6 is damaged, it is easy to replace, facilitating post-earthquake repair.

[0050] Please refer to Appendix Figure 4 , wedge-shaped slots 65 are opened at the other end of the lower flange 23 of the corbel and one end of the lower flange 33 of the steel beam. Wedge-shaped inserts 63 are formed at the ends of the damper connectors 62, and the wedge-shaped inserts 63 can be inserted into the wedge-shaped slots 65 to enable the damper connectors 62 to be inserted and bite-connected to the lower flange 33 of the steel beam and the lower flange 23 of the corbel.

[0051] By using the bite connection between the wedge-shaped inserts 63 and the wedge-shaped slots 65, the damper core 61 can be subjected to bidirectional forces under tension and compression. Not only can it ensure that under moderate and major earthquakes, the damper core 61 undergoes axial deformation with the relative displacement between the lower flange 33 of the steel beam and the lower flange 23 of the corbel, further dissipating seismic energy.

[0052] The damper core material 61 is made of mild steel with low yield strength, enabling it to deform under medium and large earthquakes. The wedge-shaped insert 63 at the end of the damper connector 62 is made of ordinary steel or high-strength steel, so that it does not deform when the damper core material fails, ensuring the reliability of the plug-in bite connection. The wedge-shaped insert 63 is welded to the damper core material 61. The tensile bearing capacity of its welded joint, as well as the axial tensile and compressive bearing capacities at the weakest section of the wedge-shaped slot 65 and the wedge-shaped insert 63, should be greater than the design value of the ultimate axial internal force borne by the mild steel damper 6 under large earthquakes, ensuring that the mild steel damper 6 can work properly under large earthquakes.

[0053] Please refer to the appendix Figure 4 , a number of third oblong holes 64 are opened on the damper core material 61, and a number of damper bolt holes 57 are opened on the lower flange connecting plate. The length direction of the third oblong holes 64 is parallel to the length direction of the steel beam 3. The damper bolts 54 can penetrate the damper bolt holes 57 and the third oblong holes 64, enabling the damper core material 61 to be slidably connected to the lower flange connecting plate through the third oblong holes 64. Through the setting of the third oblong holes 64, it is convenient for the setting and disassembly of the damper bolts 54. The setting of the damper bolts 54 can also prevent the mild steel damper 6 from falling off between the lower flange 33 of the steel beam and the lower flange 23 of the corbel.

[0054] Please refer to the appendix Figure 2 and the appendix Figure 3 , partitions 7 are provided on both the top and bottom surfaces of the damper core material 61. A number of fourth oblong holes 71 can be opened on the partitions 7. A number of the fourth oblong holes 71 are aligned with a number of the third oblong holes 64 respectively. The partitions 7 are connected and fixed to the mild steel damper 6, the first lower flange connecting plate 51, and the second lower flange connecting plate 52 through the damper bolts 54.

[0055] Preferably, both surfaces of the partition 7 are smooth surfaces. The partition 7 can be made of polytetrafluoroethylene plate or other similar materials, used to eliminate the frictional force between the mild steel damper 6 and the first lower flange connecting plate 51 and the second lower flange connecting plate 52.

[0056] The total thickness of the damper core material 61 and the upper and lower partitions 7 is equal to the thickness of the lower flange 23 of the corbel and the thickness of the lower flange 33 of the steel beam, ensuring that the first lower flange connecting plate 51 and the second lower flange connecting plate 52 exert an effective restraint on the damper core material 61 after installation, preventing the damper core material 61 from buckling under compression.

[0057] Please refer to the appendix Figure 1 to the appendix Figure 8 , the installation method and working principle of the present invention are as follows:

[0058] The steel beam 3 is hoisted into place and connected to the steel column 1 through the bracket 2 to form a beam-column connection joint. The specific operation is as follows: The steel beam 3 is hoisted into place. First, the web connection plate 41 with the first oblong hole 43 is used to connect the web of the bracket 22 and the web of the steel beam 32 through the web bolts 42. Then, the upper flange 31 of the steel beam and the upper flange 21 of the bracket are butt-welded with full penetration. Next, the steel beam lower flange 33 and the bracket lower flange 23 are connected through the first lower flange connection plate 51 and the second lower flange connection plate 52 with the second oblong hole 56 through the lower flange bolts 53. Finally, the mild steel damper 6 and the upper and lower two partition plates 7 matching the thickness of the lower flange plate are inserted into the gap between the steel beam lower flange 33 and the bracket lower flange 23, and the damper bolts 54 are installed and tightened.

[0059] The first oblong hole 43 can be set on the web of the steel beam 32 and the web of the bracket 22, or on the web connection plate 41. The allowable slip length of the first oblong hole 43 is slightly greater than the slip amount of the web bolts 42 under a major earthquake, ensuring that the bolt hole wall will not be damaged by extrusion under the action of a major earthquake. During the deformation process, the web bolts 42 can always be in a slip state.

[0060] A certain width of gap is left between the web of the steel beam 32 and the web of the bracket 22. The width of this gap is slightly greater than the relative displacement amount between the web of the steel beam 32 and the web of the bracket 22 under a major earthquake, ensuring that the web of the steel beam 32 and the web of the bracket 22 will not collide and be damaged under the action of a major earthquake.

[0061] The second oblong hole 56 can be set on the lower flange 33 of the steel beam and the lower flange 23 of the bracket, or on the lower flange connection plate. The allowable slip length of the second oblong hole 56 is slightly greater than the slip amount of the lower flange bolts 53 under a major earthquake, ensuring that the bolt hole wall will not be damaged by extrusion under the action of a major earthquake. During the deformation process, the lower flange bolts 53 can always be in a slip state. By adjusting the friction coefficients of the first friction surface 81 and the second friction surface 82, the starting slip internal force of the bracket lower flange 23 and the steel beam lower flange 33 can be controlled.

[0062] The damper core 61 is made of steel with a low yield strength, and the damper connector 62 is made of ordinary steel or high-strength steel. Multiple third oblong holes 64 are opened in the middle of the damper core 61, which can not only facilitate the penetration of the damper bolts 54, but also form a weakening in the middle of the damper core 61. Under the action of an earthquake, the middle section of the damper core 61 first enters the yield energy dissipation state.

[0063] Partition plates 7 with fourth oblong holes 71 are arranged on the upper and lower surfaces of the damper core 61 to eliminate the frictional force between the mild steel damper 6 and the first lower flange connection plate 51 and the second lower flange connection plate 52, so that the mild steel damper 6 only produces plastic deformation energy dissipation under the action of an earthquake.

[0064] Under the static load condition or under the action of minor earthquakes, the frictional force generated between the lower flange 23 of the bracket, the lower flange 33 of the steel beam, the first lower flange connecting plate 51, and the second lower flange connecting plate 52 can fully bear and transfer the internal forces of the lower flange 33 of the steel beam and the lower flange 23 of the bracket without slipping, ensuring that the joint is a fully rigid connection, and the mild steel damper 6 does not deform and does not participate in earthquake energy dissipation.

[0065] Under the action of moderate earthquakes and major earthquakes, the internal forces of the lower flange 33 of the steel beam and the lower flange 23 of the bracket exceed the frictional resistance generated between the lower flange 33 of the steel beam, the lower flange 23 of the bracket, the first lower flange connecting plate 51, and the second lower flange connecting plate 52. A relative displacement occurs between the lower flange 33 of the steel beam and the lower flange 23 of the bracket. The frictional force on the first friction surface 81 and the second friction surface 82 does work to dissipate earthquake energy. At the same time, the mild steel damper 6 deforms accordingly to dissipate earthquake energy.

[0066] If the mild steel damper 6 is damaged after the earthquake, loosen the damper bolt 54, remove the mild steel damper 6 from the side along the wedge-shaped slot 65, replace it with a new mild steel damper 6, and reinstall the damper bolt 54 to complete the post-earthquake repair of the beam-column connection joint of the present invention.

[0067] The definitions of minor earthquakes, moderate earthquakes, and major earthquakes mentioned in the present invention are as follows: Minor earthquakes refer to the earthquake intensity with an exceedance probability of approximately 63% within 50 years in this area, that is, the modal intensity, also known as the frequently-occurring earthquake. Moderate earthquakes refer to the earthquake intensity with an exceedance probability of approximately 10% within 50 years in this area, also known as the basic intensity or the fortification intensity. Major earthquakes refer to the earthquake intensity with an exceedance probability of approximately 2% - 3% within 50 years in this area, also known as the rare earthquake.

[0068] The above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the invention. Therefore, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation, characterized in that: It includes a steel column (1), a bracket (2), a steel beam (3), a web connection plate (41), a lower flange connection plate, and a mild steel damper (6); one end of the bracket (2) is installed on the steel column (1), and the upper flange of the bracket (21) at the other end of the bracket is butted and fixed to the upper flange of the steel beam (31) at one end of the steel beam (3); the web of the bracket (22) at the other end of the bracket is slidably connected to the web of the steel beam (32) at one end of the steel beam (3) through the web connection plate (41), and the lower flange of the bracket (23) at the other end of the bracket is slidably connected to the lower flange of the steel beam (33) at one end of the steel beam (3) through the lower flange connection plate; the length of the lower flange of the bracket (23) is less than the length of the web of the bracket (22), and the length of the lower flange of the steel beam (33) is less than the length of the web of the steel beam (32), so that when the bracket (2) is butted with the steel beam (3), the mild steel damper (6) can be arranged between the lower flange of the bracket (23) and the lower flange of the steel beam (33), and the mild steel damper (6) is slidably connected to the lower flange connection plate; The mild steel damper (6) includes a damper core material (61) and damper connection heads (62), and a pair of damper connection heads (62) are symmetrically arranged at both ends of the damper core material (61) respectively, and the pair of damper connection heads (62) are respectively connected to the lower flange of the steel beam (33) and the lower flange of the bracket (23) by insertion and biting connection; Wedge-shaped slots (65) are opened at the other end of the lower flange of the bracket (23) and one end of the lower flange of the steel beam (33), and wedge-shaped inserts (63) are formed at the end of the damper connection head (62), and the wedge-shaped inserts (63) can be inserted into the wedge-shaped slots (65) in a matching manner, so that the damper connection head (62) is connected to the lower flange of the steel beam (33) and the lower flange of the bracket (23) by insertion and biting connection; the wedge-shaped inserts (63) are welded to the damper core material (61), and the tensile bearing capacity of its weld seam and the axial tensile and compressive bearing capacities at the weakest cross-section of the wedge-shaped slots (65) and the wedge-shaped inserts (63) should be greater than the ultimate axial internal force design value of the mild steel damper (6) under the action of a major earthquake.

2. The post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and double energy dissipation according to claim 1, characterized in that: A number of web bolt holes (44) are opened at the other end of the web of the bracket (22) and one end of the web of the steel beam (32), and a number of first oblong holes (43) are opened on the web connection plate (41), so that the web bolts (42) can pass through the web bolt holes (44) and the first oblong holes (43), and the web of the bracket (22) is slidably connected to the web of the steel beam (32) through the web connection plate (41) via the first oblong holes (43); the length direction of the first oblong holes (43) is parallel to the length direction of the steel beam (3); there are two web connection plates (41), and the two web connection plates (41) are symmetrically arranged on both sides of the web of the bracket (22) and the web of the steel beam (32).

3. The post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation according to claim 1, characterized in that: The length of the bracket web (22) is less than the length of the bracket upper flange (21), and the length of the steel beam web (32) is less than the length of the steel beam upper flange (31). After the bracket upper flange (21) is butted with the steel beam upper flange (31), a gap is formed between the bracket web (22) and the steel beam web (32), and the width of the gap is greater than the relative displacement amount between the steel beam web (32) and the bracket web (22) under a major earthquake.

4. The post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation according to claim 1, characterized in that: A plurality of lower flange bolt holes (55) are provided at the other end of the bracket lower flange (23) and one end of the steel beam lower flange (33), and a plurality of second oblong holes (56) are provided on the lower flange connecting plate, so that the lower flange bolts (53) can penetrate through the lower flange bolt holes (55) and the second oblong holes (56), and the bracket lower flange (23) can be slidably connected to the steel beam lower flange (33) through the lower flange connecting plate via the second oblong holes (56); the length direction of the second oblong holes (56) is parallel to the length direction of the steel beam (3).

5. The post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation according to claim 4, characterized in that: The lower flange connecting plate includes a first lower flange connecting plate (51) and a second lower flange connecting plate (52); a pair of first lower flange connecting plates (51) are respectively arranged on the top surfaces of the bracket lower flange (23) and the steel beam lower flange (33) and symmetrically located on both sides of the bracket web (22) and the steel beam web (32), and a first friction surface (81) is formed between the bottom surfaces of the pair of first lower flange connecting plates (51) and the top surfaces of the bracket lower flange (23) and the steel beam lower flange (33); the second lower flange connecting plate (52) is arranged under the bottom surfaces of the bracket lower flange (23) and the steel beam lower flange (33), and a second friction surface (82) is formed between the top surface of the second lower flange connecting plate (52) and the bottom surfaces of the bracket lower flange (23) and the steel beam lower flange (33); the starting slip internal force between the bracket lower flange (23) and the lower flange connecting plate and between the steel beam lower flange (33) and the lower flange connecting plate is greater than the internal force design value of the steel beam lower flange (33) under the static condition and the action of a minor earthquake.

6. The post-earthquake replaceable steel frame beam-column connection node with multi-level fortification and double energy dissipation according to claim 1 is characterized in that: A plurality of third oblong holes (64) are provided on the damper core material (61), and a plurality of damper bolt holes (57) are provided on the lower flange connecting plate. The length direction of the third oblong holes (64) is parallel to the length direction of the steel beam (3), and the damper bolts (54) can penetrate through the third oblong holes (64) and the damper bolt holes (57), so that the damper core material (61) can be slidably connected to the lower flange connecting plate through the third oblong holes (64).

7. The post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation according to claim 6, characterized in that: Partition plates (7) are provided on both the top surface and the bottom surface of the damper core material (61), and a plurality of fourth oblong holes (71) are provided on the partition plates (7). The plurality of fourth oblong holes (71) are respectively arranged in alignment with the plurality of third oblong holes (64), and the partition plates (7) are fixedly connected to the mild steel damper (6), the first lower flange connecting plate (51), and the second lower flange connecting plate (52) through the damper bolts (54).

8. The post-earthquake replaceable steel frame beam-column connection joint with multi-level fortification and double energy dissipation according to claim 7, characterized in that: The total thickness of the damper core material (61) and the upper and lower partition plates (7) is equal to the thickness of the bracket lower flange (23) and the thickness of the steel beam lower flange (33).

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