Low-cost high-ductility fatigue-resistant core energy dissipation structure and buckling-resistant energy-dissipation support

Abstract

The present invention relates to a low-cost high-ductility fatigue-resistant core energy-dissipation structure and an anti-buckling energy-dissipation support. The core energy dissipation structure comprises at least a first steel plate and a second steel plate. The second steel plate must be and can only be adjacent to and welded to the first steel plate. The microstructure of each of two types of steel plate material used is mainly a ferrite structure; the yield strength and plastic deformation flow stress of the first steel plate material are both higher than that of the second steel plate material. In a plastic deformation strengthening stage, when true strain is not greater than 0.12, the deformation work hardening rate of the first steel plate material is not less than the deformation work hardening rate of the second steel plate material; and under fatigue deformation conditions of a strain amplitude of 1%, a loading frequency of 0.1-0.2 Hz, and a strain ratio of -1, the room-temperature fatigue life of each of the two types of steel plate material is not less than 500 cycles. The ratio of the allowable limit of displacement to the calculated yield displacement of the buckling-resistant energy-dissipation support of the present invention is not less than 7, and the allowable limit of displacement is not less than 1 / 80 of the length of the buckling-resistant energy-dissipation support.

Description

Low-cost high-ductility anti-fatigue core energy dissipation structure and buckling-restrained energy dissipation support TECHNICAL FIELD

[0001] The application belongs to the technical field of building engineering structures and relates to a low-cost high-ductility anti-fatigue core energy dissipation structure and a buckling-restrained energy dissipation support. BACKGROUND

[0002] High-intensity earthquakes and external long-duration vibrations can cause great harm to high-rise buildings and structures. Using energy dissipation devices and technologies can effectively absorb external seismic energy, reducing the damage of buildings and structures to the minimum. Buckling-restrained energy dissipation support is a common axial energy dissipation and seismic reduction element, which is widely used in civil engineering structures due to its direct force transmission path and good economy. Buckling-restrained energy dissipation support is composed of a core energy dissipation structure and a peripheral constraint member. The core energy dissipation structure plays a role in absorbing external seismic energy when the buckling-restrained energy dissipation support is subjected to periodic alternating tensile-compressive plastic deformation, while the peripheral constraint member plays a role in restraining the lateral displacement of the core energy dissipation structure and preventing the core energy dissipation structure from buckling instability. Under the action of small vibrations, the buckling-restrained energy dissipation support can provide additional lateral stiffness to the beam-column main structure and reduce structural deformation; under the action of large vibrations, the buckling-restrained energy dissipation support can realize yield deformation under tension and compression, showing good hysteretic energy dissipation characteristics.

[0003] At present, the core energy dissipation structure of the buckling-restrained energy dissipation support is mainly made of low-yield-point steel plates assembled by welding (the steel plates that make up the core energy dissipation structure are usually called 'core plates'), and the steel material of the above-mentioned core plates belongs to low-carbon ferrite steel. Due to the limited fatigue resistance of the above-mentioned core plates (and steel materials), under the action of large vibrations, the buckling-restrained energy dissipation support will fatigue fracture after a few cycles of cyclic loading, and the cumulative cyclic plastic deformation capacity and cumulative plastic energy dissipation efficiency of the buckling-restrained energy dissipation support are limited. Existing research shows that the fatigue performance of the buckling-restrained energy dissipation support made of LY160 and other low-yield-point steels as core plate materials is that under the condition of 1 / 100 of the total length of the support tensile (or compressive) displacement, the buckling-restrained energy dissipation support can basically complete about 30 cycles of tensile-compressive fatigue deformation. The inventors have found that the fundamental reason for the limited fatigue life of the above-mentioned buckling-restrained energy dissipation support lies in the premature and continuous local deformation of the core plates and the core energy dissipation structure. Therefore, inhibiting the continuous local deformation of the core plates and the core energy dissipation structure is an important technical approach to improving the anti-fatigue damage capacity of the buckling-restrained energy dissipation support.

[0004] The applicant has proposed to use low-energy Fe-Mn-Si austenitic alloy steel to develop a buckling-restrained energy dissipation support (or axial steel damper), which can be specifically referred to patent CN114351884B or CN114263287B. The low-energy Fe-Mn-Si austenitic alloy steel is usually rich in one or more of Al, Ni, and Cu elements, and has a high Mn content. Although the buckling-restrained energy dissipation support (or axial steel damper) made of low-energy Fe-Mn-Si austenitic alloy steel material has excellent fatigue resistance and cumulative cyclic plastic deformation capacity, the rich Al, Ni, and Cu elements in the alloy steel material can significantly increase the raw material cost of the alloy steel (Ni and Cu are high-priced metal materials) or increase the manufacturing process cost of the alloy steel (Al reduces the fluidity of the molten steel during alloy steel smelting, increases the difficulty of removing inclusions in the molten steel, thereby increasing the manufacturing difficulty and process cost of the alloy steel). Therefore, the buckling-restrained energy dissipation support (or axial steel damper) made of low-energy Fe-Mn-Si austenitic alloy steel does not have an advantage in cost. Under the premise of meeting the anti-seismic protection requirements, engineering projects often focus on the cost performance of the damping component, that is, the required buckling-restrained energy dissipation support type axial energy dissipation and seismic mitigation component only needs to have enhanced ductility and fatigue resistance capacity on the basis of moderate price, and does not need to have the super-high ductility and excellent fatigue resistance provided by the buckling-restrained energy dissipation support / axial steel damper made of low-energy Fe-Mn-Si austenitic alloy steel.

[0005] In view of the above technical problems and actual application needs, it is urgent to develop a high-ductility anti-fatigue buckling-restrained energy dissipation support with lower cost. The developed buckling-restrained energy dissipation support needs to have outstanding high-ductility and anti-fatigue failure capacity compared with conventional buckling-restrained energy dissipation supports; compared with the buckling-restrained energy dissipation support / axial steel damper made of low-energy Fe-Mn-Si austenitic alloy steel, the newly developed buckling-restrained energy dissipation support needs to have a significant low-cost advantage. SUMMARY

[0006] The present application provides a low-cost high-ductility anti-fatigue core energy dissipation structure and a buckling-restrained energy dissipation support. The buckling-restrained energy dissipation support of the present application can replace the existing buckling-restrained energy dissipation support to significantly improve the seismic protection performance of the building.

[0007] The new buckling-restrained energy dissipation support of the present application can delay or inhibit the premature occurrence of sustained local deformation of the core energy dissipation structure, thereby significantly improving the ductility and fatigue resistance of the buckling-restrained energy dissipation support.

[0008] The object of the present application can be achieved by the following technical solutions.

[0009] The present application provides a low-cost high-ductility anti-fatigue core energy dissipation structure for buckling-restrained energy dissipation brace, which can absorb external vibration energy when the buckling-restrained energy dissipation brace is subjected to cyclic alternating tensile-compressive plastic deformation,

[0010] The low-cost high-ductility anti-fatigue core energy dissipation structure comprises at least a first steel plate and a second steel plate, the second steel plate must be adjacent to and connected with the first steel plate by welding, and the connecting weld between the first steel plate and the second steel plate is parallel to the axial direction of the core energy dissipation structure;

[0011] The yield strength and plastic deformation flow stress of the first steel plate material are greater than those of the second steel plate material, and the yield strength of the first steel plate material is greater than that of the second steel plate material by more than 40 MPa;

[0012] In the plastic deformation strengthening stage, when the true strain is not greater than 0.12, the plastic deformation work hardening rate of the first steel plate material is not less than that of the second steel plate material;

[0013] Under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.1-0.2 Hz, and a strain ratio of -1, the room temperature fatigue life of the first steel plate material and the second steel plate material is not less than 500 cycles;

[0014] The mass percentage of the chemical composition of the first steel plate material is: 0.05%≤C≤0.25%, Mn≤1.8%, Si≤1.0%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest is Fe and inevitable impurity elements; the yield strength of the first steel plate material is between 180 MPa and 400 MPa, and the elongation after fracture is not less than 26%; the microstructure of the first steel plate material comprises ferrite structure with a volume fraction of not less than 85%, and the average size of the ferrite grains is not greater than 200 μm; when the microstructure of the first steel plate material is not entirely ferrite structure, the remaining structure is one or more than one of α′ martensite or carbide;

[0015] The mass percentage of the chemical composition of the second steel plate material is: C≤0.22%, Mn≤1.5%, Si≤0.8%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest is Fe and inevitable impurity elements; the yield strength of the second steel plate material is not greater than 300 MPa, and the elongation after fracture is not less than 28%; the microstructure of the second steel plate material is ferrite and carbide with a volume fraction of not more than 6%, and the average size of the ferrite grains is not greater than 200 μm;

[0016] Further, the first steel plate material further comprises one or more of Ti, Nb, and V, and the mass percentage of Ti, Nb, and V is Ti≤0.1%, Nb≤0.1%, and V≤0.15%;

[0017] Further, the second steel plate material further comprises one or more of Ti, Nb, and V, and the mass percentage of Ti, Nb, and V is Ti≤0.08%, Nb≤0.08%, and V≤0.1%;

[0018] The thickness of the first steel plate is 0.5 times or more of the thickness of the second steel plate.

[0019] In the low-cost high-ductility anti-fatigue core energy dissipation structure, the ratio of the sum of the cross-sectional areas of all the second steel plate core energy dissipation segments to the sum of the cross-sectional areas of all the first steel plate core energy dissipation segments is not less than 0.6; when the low-cost high-ductility anti-fatigue core energy dissipation structure only comprises one first steel plate, the sum of the cross-sectional areas of all the first steel plate core energy dissipation segments is the cross-sectional area of the first steel plate core energy dissipation segment; when the low-cost high-ductility anti-fatigue core energy dissipation structure only comprises one second steel plate, the sum of the cross-sectional areas of all the second steel plate core energy dissipation segments is the cross-sectional area of the second steel plate core energy dissipation segment.

[0020] When the second steel plate is not adjacent to the first steel plate on both sides, the product of the distance from the connecting weld between the two types of adjacent connected steel plates to any non-welding side of the second steel plate core energy dissipation segment and the thickness of the second steel plate is 2.5 times or less of the cross-sectional area of the core energy dissipation segment of the adjacent connected first steel plate; and the ratio of the distance from the connecting weld between the two types of adjacent connected steel plates to any non-welding side of the second steel plate core energy dissipation segment to the thickness of the second steel plate is not more than 20. The distance from the connecting weld between the two types of adjacent connected steel plates to any non-welding side of the second steel plate core energy dissipation segment, the thickness of the second steel plate, and the cross-sectional area of the core energy dissipation segment of the first steel plate all use consistent units of measurement when measured or calculated, such as distance in millimeters, thickness in millimeters, and cross-sectional area in square millimeters.

[0021] The application provides: in the low-cost high-ductility anti-fatigue core energy consumption structure, if the cross-sectional geometry of the first steel plate or the second steel plate remains unchanged along the length direction, the core energy consumption section of the first steel plate or the second steel plate is the full length of the first steel plate or the second steel plate, at this time, the cross section of the core energy consumption section of the first steel plate or the second steel plate is the cross section of the first steel plate or the second steel plate; if the cross-sectional geometry of the first steel plate or the second steel plate presents the characteristics of wide at both ends and narrow in the middle along the length direction, the core energy consumption section of the first steel plate or the second steel plate is the narrow part in the middle of the first steel plate or the second steel plate, at this time, the cross section of the core energy consumption section of the first steel plate or the second steel plate is the cross section of the narrow part in the middle of the first steel plate or the second steel plate.

[0022] The application provides: in the low-cost high-ductility anti-fatigue core energy consumption structure, the second steel plate must be adjacent to the first steel plate and connected by welding; and the yield strength and plastic deformation flow stress of the first steel plate material are greater than the yield strength and plastic deformation flow stress of the second steel plate material, and the yield strength of the first steel plate material is greater than the yield strength of the second steel plate material by more than 40 MPa. Because the first steel plate and the second steel plate are closely connected, in the cyclic deformation process, the two types of steel plates form a constraint structure, the cyclic deformation stress is redistributed between the two types of steel plates, and the two types of steel plates maintain deformation strain compatibility at the connecting weld.

[0023] In the application, the mechanical properties of the steel plate material are inherent properties of the steel plate material, which are associated with the chemical composition and microstructure of the steel plate material (further, the microstructure of the steel plate material is closely related to the chemical composition and preparation process of the steel plate material), and the basic performance data are obtained by the experimental method conforming to the national standard. The yield strength, plastic deformation flow stress and plastic deformation work hardening rate of the steel plate material are described as follows.

[0024] The yield strength refers to the minimum stress value when the material begins to have obvious plastic deformation (also expressed as the yield limit when the material has yield phenomenon); for the metal material without obvious yield, the stress value producing 0.2% residual deformation is defined as the yield strength.

[0025] The plastic deformation flow stress refers to the stress produced by the material in plastic deformation, which is the same as the stress on the true stress-strain curve, that is, the stress corresponding to the true strain. Usually, the true stress is represented by σ, and the true strain is represented by ε. The corresponding engineering stress and engineering strain are σ e and e, and the relationship between them is σ e (1+e), ε=ln(1+e). Therefore, the true stress-strain curve can be obtained from the engineering stress-strain curve.

[0026] The plastic deformation work hardening rate is used to represent the hardening behavior of the material during plastic deformation, which can be mathematically equivalent to the slope dσ / dε of the true stress-strain curve. The higher the work hardening rate, the more obvious the hardening of the material during plastic deformation, and the greater the slope of the true stress-strain curve.

[0027] The deformation strengthening stage refers to: the material enters the plastic deformation stage; and with the increase of the deformation strain, the stress borne by the material also gradually increases. After the deformation strengthening stage ends, the material deformation enters the local inhomogeneous deformation stage, i.e. the necking stage.

[0028] In addition, it should be pointed out that in the core energy dissipation structure, the fatigue failure resistance of the core plate (i.e. the first steel plate and the second steel plate) is not completely equivalent to that of the core plate material (i.e. the first steel plate material and the second steel plate material) (the latter is obtained by the experimental method conforming to the national standard); the fatigue failure resistance of the core plate is not only related to the fatigue deformation performance of the core plate material, but also closely related to the intactness of the cutting side surface of the core plate after cutting and blanking. The core plate constituting the core energy dissipation structure inevitably has cutting side surface defects (although the defect size can be reduced to a certain extent through polishing process), which will accelerate the continuous local inhomogeneous deformation of the core plate during fatigue deformation, and further induce premature fatigue fracture of the core plate. The applicant of the present application found that the good work hardening capacity and cyclic deformation work hardening capacity of the core plate material help to delay the local inhomogeneous deformation of the core plate during fatigue deformation, inhibit or even prevent the continuity of the local inhomogeneous deformation, and further help to enhance the fatigue failure resistance of the core plate and the core energy dissipation structure as a whole.

[0029] Since the yield strength and plastic deformation flow stress of the first steel plate material are greater than the yield strength and plastic deformation flow stress of the second steel plate material respectively, the cyclic deformation stress of the first steel plate material is also greater than the cyclic deformation stress of the second steel plate material under the condition of the same strain amplitude of cyclic deformation. When the true strain is not greater than 0.12 in the deformation strengthening stage, the plastic deformation work hardening rate of the first steel plate material is not less than the plastic deformation work hardening rate of the second steel plate material, so that the cyclic deformation work hardening rate of the first steel plate material is also not less than the cyclic deformation work hardening rate of the second steel plate material with the increase of the strain amplitude in the range of large strain amplitude of cyclic deformation. When the yield strength of the first steel plate material is greater than the yield strength of the second steel plate material by more than 40 MPa, the plastic deformation flow stress and the cyclic deformation stress of the first steel plate material are greater than the plastic deformation flow stress and the cyclic deformation stress of the second steel plate material respectively, and the cyclic deformation work hardening rate of the first steel plate material is not less than the cyclic deformation work hardening rate of the second steel plate material, a strong constraint connection is formed between the two types of steel plates in the core energy dissipation structure, and the local inhomogeneous deformation of the second steel plate in the cyclic deformation process is significantly inhibited by the first steel plate and the connecting weld; compared with the unconstrained case of the two types of steel plates, the strong constraint action between the two types of steel plates can significantly improve the fatigue resistance of the second steel plate, and further improve the fatigue resistance and ductility of the whole core energy dissipation structure. The application limits that the second steel plate must and can only be connected with the first steel plate, and the purpose is to use the high plastic deformation flow stress and excellent work hardening capacity of the first steel plate material to improve the ability of the second steel plate to resist local inhomogeneous deformation and the fatigue resistance in the core energy dissipation structure; if the second steel plate is only connected with itself, the fatigue resistance of the second steel plate cannot be improved.

[0030] In addition, the application provides that under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.1-0.2 Hz and a strain ratio of-1, the room temperature fatigue life of the first steel plate material and the second steel plate material is not less than 500 cycles. The purpose of the above provision is to provide a necessary condition for the core energy dissipation structure to have good fatigue resistance.

[0031] The application further limits the chemical composition, microstructure and mechanical properties of the two types of steel plate materials.

[0032] The microstructure of the first steel plate material and the second steel plate material is mainly ferrite structure, and the average size of the ferrite grains is not greater than 200 μm. The provision that the microstructure of the two types of steel plate materials is mainly ferrite structure is to enable the material composition to be designed simply as low-carbon and low-alloy, thereby significantly reducing the material cost. The application limits that the average grain size of the ferrite is not more than 200 μm; this is because when the ferrite grains are too large, fatigue cracks will easily be initiated and propagated from the ferrite grain boundaries, thereby significantly reducing the fatigue resistance of the two types of steel plates and the whole core energy dissipation structure.

[0033] The first steel plate material has a chemical composition with mass percentage of 0.05%≤C≤0.25%, Mn≤1.8%, Si≤1.0%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest of Fe and inevitable impurity elements. In addition, Cu, Cr or Ni elements can be added to improve the corrosion resistance of the first steel plate material, and the present application limits the content of Cu, Cr and Ni elements to be no more than 1.0%. The yield strength of the first steel plate material is limited to be between 180MPa and 400MPa, which aims to ensure that the core energy dissipation structure and the buckling-restrained energy dissipation support have lower yield force and yield displacement and higher ductility. The microstructure of the first steel plate material mainly contains ferrite structure with volume fraction no less than 85% (when the microstructure of the first steel plate material is not entirely ferrite structure, the remaining structure is one or more than one of α'martensite or carbide), the elongation after fracture of the first steel plate material is no less than 26%, and the fatigue life of the first steel plate material at room temperature under the fatigue deformation loading condition of strain amplitude 1%, loading frequency 0.1-0.2Hz and strain ratio-1 is no less than 500 cycles, which aims to ensure that the first steel plate material has good ductility and fatigue resistance, so that the core energy dissipation structure has good ductility and fatigue resistance.

[0034] Further, the alloying elements of the first steel plate material can also contain one or more than one of Ti, Nb and V elements, and the mass percentage of Ti, Nb and V elements is limited to Ti≤0.1%, Nb≤0.1% and V≤0.15%. At this time, the chemical composition of the first steel plate material has mass percentage of 0.05%≤C≤0.25%, Mn≤1.8%, Si≤1.0%, Ti≤0.1%, Nb≤0.1%, V≤0.15%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest of Fe and inevitable impurity elements. Since Ti, Nb and V elements are strong carbide-forming elements, adding excessive Ti, Nb and V elements will form carbide particles with too high volume content in the material matrix, which will excessively increase the yield strength and plastic deformation flow stress of the first steel plate material and significantly weaken the fatigue resistance, thereby significantly increasing the yield displacement of the core energy dissipation structure and reducing the fatigue resistance and ductility of the core energy dissipation structure. Therefore, the present application limits the addition amount of Ti, Nb and V elements.

[0035] The second steel plate material has the following chemical composition in mass percentage: C≤0.22%, Mn≤1.5%, Si≤0.8%, P≤0.045%, S≤0.03%, N≤0.03%, and the balance of Fe and inevitable impurities. In addition, Cu, Cr or Ni elements can be added to improve the corrosion resistance of the second steel plate material, and the content of Cu, Cr and Ni elements is limited to not more than 1.0% according to the present application. The microstructure of the second steel plate material is limited to ferrite and carbides with a volume fraction of not more than 6%, the elongation after fracture of the second steel plate material is limited to not less than 28%, and the fatigue life of the second steel plate material at room temperature under the fatigue deformation loading condition of strain amplitude 1%, loading frequency 0.1-0.2 Hz and strain ratio-1 is limited to not less than 500 cycles, so as to ensure that the second steel plate material has good fatigue resistance. The second steel plate material has the above-mentioned alloy composition and microstructure, and the yield strength of the second steel plate material is limited to not more than 300 MPa, which helps to reduce the yield force and yield displacement of the overall core energy dissipation structure, thereby helping the core energy dissipation structure and the buckling-restrained energy dissipation brace to have higher ductility.

[0036] Further, the alloy composition of the second steel plate material can further include one or more of Ti, Nb and V elements, and the mass percentage of Ti, Nb and V elements is limited to Ti≤0.08%, Nb≤0.08% and V≤0.1%. At this time, the second steel plate material has the following chemical composition in mass percentage: C≤0.22%, Mn≤1.5%, Si≤0.8%, Ti≤0.08%, Nb≤0.08%, V≤0.1%, P≤0.045%, S≤0.03%, N≤0.03%, and the balance of Fe and inevitable impurities. Similarly, excessive addition of Ti, Nb and V elements will form carbide particles with too high volume content in the material matrix, thereby excessively increasing the yield strength and plastic deformation flow stress of the second steel plate material and significantly reducing the fatigue resistance, and further significantly increasing the yield displacement of the core energy dissipation structure and reducing the fatigue resistance and ductility of the core energy dissipation structure. Therefore, the present application limits the addition amount of Ti, Nb and V elements.

[0037] The present application limits the thickness of the first steel plate to be more than 0.5 times the thickness of the second steel plate. This is because, when the thickness of the first steel plate is less than 0.5 times the thickness of the second steel plate, the first steel plate is not easy to fully constrain the deformation of the second steel plate through the connecting weld during the tensile-compressive alternating plastic deformation.

[0038] The ratio of the sum of the cross-sectional areas of all the second steel plate core energy dissipation segments to the sum of the cross-sectional areas of all the first steel plate core energy dissipation segments is not less than 0.6. If the ratio of the sum of the cross-sectional areas of all the second steel plate core energy dissipation segments to the sum of the cross-sectional areas of all the first steel plate core energy dissipation segments is too small (less than 0.6), the load bearing of the core energy dissipation structure is mainly dominated by the first steel plate, which significantly increases the yield force and yield displacement of the core energy dissipation structure, and further reduces the ductility of the core energy dissipation structure and the buckling-restrained energy dissipation support.

[0039] In an embodiment of the present application, when the second steel plate is not adjacent to the first steel plate on both sides thereof, the product of the distance from the connecting weld between the two types of steel plates of the adjacent connection to any non-welding side of the second steel plate core energy dissipation segment and the thickness of the second steel plate is less than 2.5 times the cross-sectional area of the core energy dissipation segment of the first steel plate of the adjacent connection; and the ratio of the distance from the connecting weld between the two types of steel plates of the adjacent connection to any non-welding side of the second steel plate core energy dissipation segment to the thickness of the second steel plate is not greater than 20. Here, the following two connection modes of the second steel plate and the adjacent first steel plate need to be considered:

[0040] First, the second steel plate is adjacent to the first steel plate on only one side, i.e., the connecting weld between the two types of steel plates is located on one side of the second steel plate, at this time, the second steel plate has only one non-welding side. Common connection forms include: 2 second steel plates and 1 first steel plate are connected to form a cross-shaped structure, wherein the 2 second steel plates are vertically located above and below the first steel plate, respectively; 1 second steel plate and 1 first steel plate are connected to form a T-shaped structure, wherein the second steel plate is placed perpendicular to the first steel plate, and the connecting weld between the two types of steel plates is located on the first steel plate (i.e., the connecting weld is located between the two sides of the first steel plate).

[0041] Second, the connecting weld between the two types of steel plates is located above the second steel plate, i.e., the connecting weld is located between the two sides of the second steel plate (the connecting weld is not on any side of the second steel plate), at this time, the second steel plate has two non-welding sides. Common connection forms include: 2 second steel plates and 1 first steel plate are connected to form an I-shaped structure, wherein the first steel plate is vertically located between the 2 second steel plates; 1 second steel plate and 1 first steel plate are connected to form a T-shaped structure, wherein the second steel plate is placed perpendicular to the first steel plate.

[0042] For the above two cases, if the product of the distance from the connecting weld between the two types of steel plates to any non-welded side of the core energy dissipation section of the second steel plate and the thickness of the second steel plate is more than 2.5 times the cross-sectional area of the core energy dissipation section of the adjacent connected first steel plate, the constraint effect of the first steel plate on the second steel plate as a whole is limited, and the fatigue resistance of the second steel plate as a whole cannot be significantly improved, thereby the fatigue resistance of the core energy dissipation structure as a whole and the buckling-restrained energy dissipation support cannot be significantly enhanced. Similarly, when the ratio of the distance from the constraint connecting weld to any non-welded side of the core energy dissipation section of the second steel plate to the thickness of the second steel plate is too large (greater than 20), the constraint effect on the part of the material of the second steel plate far from the weld is almost lost, and this part of the material is prone to fatigue failure compared with the material near the weld constraint, thereby leading to failure and destruction of the entire second steel plate and the core energy dissipation structure. Therefore, the present application limits that the product of the distance from the constraint connecting weld to any non-welded side of the core energy dissipation section of the second steel plate and the thickness of the second steel plate is less than 2.5 times the cross-sectional area of the core energy dissipation section of the adjacent connected first steel plate; and the ratio of the distance from the constraint connecting weld to any non-welded side of the core energy dissipation section of the second steel plate to the thickness of the second steel plate is not greater than 20.

[0043] When the second steel plate is connected with the adjacent first steel plates on both sides, the second steel plate is constrained and protected on both sides, and therefore fatigue cracks cannot be formed from both sides, which can significantly improve the fatigue resistance of the second steel plate. In the present application, when the second steel plate is connected with the first steel plates on both sides, the condition "the ratio of the sum of the cross-sectional areas of all core energy dissipation sections of the second steel plate to the sum of the cross-sectional areas of all core energy dissipation sections of the first steel plates is not less than 0.6; and the ratio of the cross-sectional area of the core energy dissipation section of the constraint connected second steel plate to the cross-sectional area of any core energy dissipation section of the adjacent first steel plate is not greater than 5.0" needs to be met. And from the perspective of deformation stability of the core energy dissipation structure, it is suggested that the distance between the welds on both sides of the second steel plate is not more than 80 times the thickness of the second steel plate.

[0044] The case that the second steel plate is connected with the first steel plates on both sides includes that one second steel plate and two first steel plates are connected to form an I-shaped structure, wherein the second steel plate is vertically located between the two first steel plates.

[0045] In an embodiment of the present application, the cross section of the core energy dissipation structure can have any type of axisymmetric geometric shape. The cross-sectional form with any type of axisymmetric geometric shape mainly includes cross-shaped and I-shaped.

[0046] In one embodiment of the present application, the core energy dissipation structure of the buckling-restrained energy dissipation brace has a cross-section shape of narrow in the middle and wide at both ends, as shown in Figs. 1 and 2. Fig. 1 shows the geometry and relative position of the first steel plate and the second steel plate constituting a core energy dissipation structure, and Fig. 2 shows a schematic view of the core energy dissipation structure formed by welding the two types of steel plates.

[0047] In the present application, when the two types of steel plates have a geometry shape of narrow in the middle and wide at both ends (the narrow part in the middle of the steel plate is referred to as the core energy dissipation segment), the narrow part in the middle of the core energy dissipation structure composed of the two types of steel plates is referred to as the core energy dissipation segment of the core energy dissipation structure. Since the buckling-restrained energy dissipation brace is connected to the beam-column main structure or other steel braces of the building through the connection joint or other connecting members, the above-mentioned cross-section geometry design of the core energy dissipation structure is to make the plastic deformation of the buckling-restrained energy dissipation brace concentrate only in the core energy dissipation segment of the core energy dissipation structure, so as to avoid the connection joint or other connecting members from possibly undergoing significant yield deformation or even damage during the service of the buckling-restrained energy dissipation brace.

[0048] The reasonable selection of the ratio of the cross-sectional area of the core energy dissipation segment to the cross-sectional area of the both ends of the core energy dissipation structure mainly depends on the material strength of the core energy dissipation structure and the connection joint (or other connecting members) and the connecting strength therebetween. In principle, the yield force of the connection joint (or other connecting members) when yielding needs to be greater than the yield force of the core energy dissipation structure when yielding.

[0049] The present application also provides a buckling-restrained energy dissipation brace comprising the above-mentioned core energy dissipation structure and a peripheral constraint member, wherein the core energy dissipation structure serves to absorb external seismic energy when the buckling-restrained energy dissipation brace undergoes periodic alternating tensile-compressive plastic deformation, and the peripheral constraint member serves to constrain the lateral displacement of the core energy dissipation structure and prevent the core energy dissipation structure from buckling instability.

[0050] There is a layer of unbonding material between the peripheral constraint member and the core energy dissipation structure, so as to eliminate the bonding friction therebetween.

[0051] In one embodiment of the present application, the peripheral constraint member of the buckling-restrained energy dissipation brace can be selected as a constraint sleeve formed by combining a steel pipe with inner filled concrete, or a reinforced concrete constraint sleeve, or a pure steel type structure constraint.

[0052] This invention defines the ultimate permissible displacement and calculated yield displacement of a buckling-restrained energy dissipation brace. The ultimate permissible displacement is the maximum tensile (or compressive) displacement allowed during cyclic alternating tensile-compression plastic deformation of the buckling-restrained energy dissipation brace, at which the brace can withstand at least 30 cycles of cyclic tensile-compression plastic deformation. When the tensile (or compressive) displacement of the cyclic deformation exceeds this maximum permissible displacement, the buckling-restrained energy dissipation brace fails to complete 30 cycles of cyclic deformation. The calculated yield displacement represents the displacement corresponding to yielding when the buckling-restrained energy dissipation brace undergoes cyclic alternating tensile-compression deformation at the ultimate permissible displacement. Figure 3 illustrates the hysteresis curve formed by the buckling-restrained energy dissipation brace during cyclic alternating tensile-compression plastic deformation at the ultimate permissible displacement. The elastic stiffness of the buckling-restrained energy dissipation brace is obtained from the unloading segment of the hysteresis curve. When the center of the hysteresis curve is not at the origin of the coordinate axis, the maximum displacement of the tensile portion of the hysteresis curve is... The maximum displacement of the compression portion of the hysteresis curve is Then the limit allowable displacement u d,max Count as If the center of the hysteresis curve is at the origin of the coordinate axis, then the maximum displacement of the stretching part of the hysteresis curve is the same as the maximum displacement of the compression part. In this case, we have: The elastic stiffness corresponding to the unloading section of the hysteresis curve under tension is: The elastic stiffness corresponding to the unloading segment of the compression part of the hysteresis curve is if The elastic stiffness K of the buckling-resistance energy dissipation brace d Count as if At this point, there is elastic stiffness supported by buckling-resistance energy dissipation bracing. Draw a line through the origin with a slope equal to the elastic stiffness K. d The displacement corresponding to the intersection of the straight line and the tensile portion of the hysteresis curve is the calculated yield displacement during cyclic deformation tensile testing. The displacement corresponding to the intersection of the straight line and the compression portion of the hysteresis curve is the calculated yield displacement during cyclic deformation compression. Calculation of yield displacement u of buckling-restrained energy dissipation brace dy Count as From the limit allowable displacement u d,max Calculation of yield displacement u dy The u of the buckling-resistance energy dissipation support can then be obtained. d,max with u dy The ratio of the two values ​​is the ductility coefficient of the buckling-resistance energy dissipation brace.

[0053] The ductility and fatigue properties of the buckling-resistance energy dissipation brace of the present invention are as follows:

[0054] When the yield strength of the second steel plate material is less than or equal to 180 MPa, the ratio of the ultimate allowable displacement of the buckling-restrained energy dissipation brace to the calculated yield displacement is not less than 9, and the ultimate allowable displacement is not less than 1 / 70 of the length of the buckling-restrained energy dissipation brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the bearing capacity attenuation is less than 15%;

[0055] When the yield strength of the second steel plate material is greater than 180 MPa and not greater than 300 MPa, the ratio of the ultimate allowable displacement of the buckling-restrained energy dissipation brace to the calculated yield displacement is not less than 7, and the ultimate allowable displacement is not less than 1 / 80 of the length of the buckling-restrained energy dissipation brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the bearing capacity attenuation is less than 15%.

[0056] In addition, since the core energy dissipation structure has good ability to resist local non-uniform deformation, the buckling-restrained energy dissipation brace of the present application can withstand tensile-compressive cyclic plastic deformation at high speed (or high strain rate).

[0057] The fatigue resistance and / or ductility of the buckling-restrained energy dissipation brace of the present application can be significantly better than that of a buckling-restrained energy dissipation brace made of only the first steel plate or the second steel plate.

[0058] The present application also provides the use of the buckling-restrained energy dissipation brace, which is used alone or in combination with other steel braces to form an axial energy dissipation brace, installed in a building or structure, connected with the beam-column main structure and connection joint of the building or structure to form an integral whole, and plays a role in dissipating external seismic energy, which can significantly improve the seismic performance of the building and structure.

[0059] In an embodiment of the present application, the buckling-restrained energy dissipation brace can be connected with other steel braces through flanges or intermediate connecting plates to form an axial energy dissipation brace to meet the requirements of prefabricated buildings and rapid replacement after earthquakes.

[0060] Compared with the prior art, the present application has the following advantages:

[0061] 1) Compared with the prior art buckling-restrained energy dissipation brace (the core energy dissipation structure is usually made of low yield point steel), the buckling-restrained energy dissipation brace of the present application has good ductility, fatigue resistance and cumulative cyclic plastic deformation capacity.

[0062] 2) Compared with buckling-restrained energy dissipation brace or axial steel damper made of low stacking fault energy Fe-Mn-Si series austenitic alloy steel, the buckling-restrained energy dissipation brace of the application has obvious low cost advantage, because the steel plate material cost of the core energy dissipation structure of the buckling-restrained energy dissipation brace of the application is significantly lower than the low stacking fault energy Fe-Mn-Si series austenitic alloy steel material cost.

[0063] 3) Compared with the existing buckling-restrained energy dissipation brace, the buckling-restrained energy dissipation brace of the application can withstand tensile-compression cyclic plastic deformation at high speed (or high strain rate). BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is the geometric shape and relative position of the first steel plate and the second steel plate constituting a core energy dissipation structure.

[0065] Figure 2 is a schematic diagram of a core energy dissipation structure of a buckling-restrained energy dissipation brace.

[0066] Figure 3 is the hysteresis curve formed when the buckling-restrained energy dissipation brace is subjected to periodic alternating tensile-compression plastic deformation at the limit allowable displacement. The ductility coefficient of the buckling-restrained energy dissipation brace is obtained from the limit allowable displacement and the calculated yield displacement.

[0067] Figure 4 is the geometric shape of the first steel plate constituting the core energy dissipation structure of the buckling-restrained energy dissipation brace in Example 1.

[0068] Figure 5 is the geometric shape of the second steel plate constituting the core energy dissipation structure of the buckling-restrained energy dissipation brace in Example 1.

[0069] Figure 6 is the engineering stress-strain curve of the first steel plate material and the second steel plate material constituting the core energy dissipation structure in Example 1.

[0070] Figure 7 is the true stress-strain curve of the first steel plate material and the second steel plate material constituting the core energy dissipation structure in Example 1.

[0071] Figure 8 is the change relationship of the plastic deformation work hardening rate of the first steel plate material and the second steel plate material constituting the core energy dissipation structure in Example 1 with the true strain.

[0072] Figure 9 is a front view of the core energy dissipation structure of the buckling-restrained energy dissipation brace in Example 1.

[0073] Figure 10 is a top view of the core energy dissipation structure of the buckling-restrained energy dissipation brace in Example 1.

[0074] Figure 11 is a side view of the core energy dissipation structure of the buckling-restrained energy dissipation brace in Example 1.

[0075] Figure 12 is a front view of the buckling-restrained energy dissipation brace in Example 1.

[0076] Fig. 13 is a plan view of the buckling-restrained energy dissipation brace in Example 1.

[0077] Fig. 14 is a section view of the buckling-restrained energy dissipation brace in Example 1 along A-A.

[0078] Fig. 15 is a hysteresis curve corresponding to the plastic deformation of the buckling-restrained energy dissipation brace in Example 1 subjected to tensile-compressive cyclic deformation at a loading frequency of 0.2 Hz.

[0079] Fig. 16 is a hysteresis curve corresponding to the plastic deformation of the buckling-restrained energy dissipation brace in Example 2 subjected to tensile-compressive cyclic deformation at a loading frequency of 1.75 Hz.

[0080] Reference numerals in the drawings: 1, first steel plate; 2, second steel plate; 21, welded side; 22, non-welded side; 3, weld; 4, peripheral constraint steel tube; 5, buckling-restrained energy dissipation brace; 6, concrete. DETAILED DESCRIPTION

[0081] The present application will be described in detail below with reference to the accompanying drawings and specific examples.

[0082] Example 1:

[0083] A buckling-restrained energy dissipation brace is composed of a low-cost high-ductility fatigue-resistant core energy dissipation structure and a peripheral constraint member.

[0084] The core energy dissipation structure has a cross section with a cruciform axisymmetric geometry, with the axis of symmetry being the axial direction of the buckling-restrained energy dissipation brace, and the cross section being narrow in the middle and wide at both ends along the axial direction. As shown in Figs. 1 and 2, the core energy dissipation structure is composed of one first steel plate 1 and two second steel plates 2, the first steel plate 1 and the second steel plates 2 being the same in longitudinal length; the two second steel plates 2 are respectively disposed above and below the first steel plate 1, with the longitudinal center line of the first steel plate 1 as the axis of symmetry; the two second steel plates 2 are respectively tightly connected to the first steel plate 1 by welding, with the welds 3 being parallel to the axial direction of the core energy dissipation structure and the buckling-restrained energy dissipation brace. In Fig. 1, the two sides of the second steel plate 2 are respectively the welded side 21 and the non-welded side 22.

[0085] The geometry of the first steel plate constituting the core energy dissipation structure is shown in Fig. 4. The total length of the first steel plate L = 2000 mm; the length of the core energy dissipation section of the first steel plate L0= 1530 mm, the width W0= 150 mm; the thickness of the first steel plate T = 16 mm.

[0086] The chemical composition and its mass percentage of the first steel plate material are: 0.54% Mn, 0.16% Si, 0.19% C, 0.013% P, 0.006% S, 0.006% N, and the rest is Fe and inevitable impurity elements. The yield strength of the first steel plate material is 282 MPa, and the elongation after fracture is 36%. Under the fatigue deformation loading conditions of strain amplitude 1%, loading frequency 0.2 Hz, and strain ratio -1, the room temperature fatigue life of the first steel plate material is about 1000 cycles. The microstructure of the first steel plate material is mainly ferrite structure (the ferrite matrix contains carbides with a volume fraction not more than 6%), and the average ferrite grain size is about 50 μm.

[0087] The geometric shape of the second steel plate constituting the core energy dissipation structure is shown in Fig. 5. The total length of the second steel plate is l = 2000 mm; the length of the core energy dissipation section of the second steel plate is l0= 1530 mm, and the width is w0 / 2 = 75 mm; the thickness of the second steel plate is t = 16 mm.

[0088] The chemical composition and its mass percentage of the second steel plate material are: 0.08% Mn, less than 0.02% Si, 0.003% C, 0.01% P, 0.015% S, 0.005% N, and the rest is Fe and inevitable impurity elements. The yield strength of the second steel plate material is 153 MPa, and the elongation after fracture is 48%. Under the fatigue deformation loading conditions of strain amplitude 1%, loading frequency 0.2 Hz, and strain ratio -1, the room temperature fatigue life of the second steel plate material is about 1300 cycles. The microstructure of the second steel plate material is ferrite structure (the ferrite matrix is distributed with a small amount of carbide particles), and the average ferrite grain size is about 50 μm.

[0089] Fig. 6 is the engineering stress-strain curve of the first steel plate material and the second steel plate material. Fig. 7 is the true stress-strain curve of the first steel plate material and the second steel plate material. Fig. 8 is the plastic deformation work hardening rate curve of the first steel plate material and the second steel plate material with true strain. As shown in Figs. 6 and 7, the yield strength and plastic deformation flow stress of the first steel plate material are greater than those of the second steel plate material, and the yield strength of the first steel plate material is 129 MPa greater than that of the second steel plate material. As shown in Fig. 8, in the deformation strengthening stage, when the true strain is not greater than 0.12, the plastic deformation work hardening rate of the first steel plate material is greater than that of the second steel plate material. In addition, under the fatigue deformation loading conditions of strain amplitude 1%, loading frequency 0.1-0.2 Hz, and strain ratio -1, the room temperature fatigue life of the first steel plate material and the second steel plate material is not less than 500 cycles.

[0090] The thickness of the first steel plate is the same as the thickness of the second steel plate. The ratio of the sum of the cross-sectional areas of the two second steel plate core energy consumption segments to the cross-sectional area of the first steel plate core energy consumption segment is 1.0. After welding and assembly, the product of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welding side of the second steel plate core energy consumption segment (i.e., the width w0 / 2 of the second steel plate core energy consumption segment) and the thickness (t) of the second steel plate is 0.5 times the cross-sectional area (W0T) of the adjacent first steel plate core energy consumption segment. The ratio of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welding side of the second steel plate core energy consumption segment (i.e., the width w0 / 2 of the second steel plate core energy consumption segment) to the thickness (t) of the second steel plate is about 4.7.

[0091] After welding and assembly, the front view, top view and side view of the core energy consumption structure are shown in Figures 9, 10 and 11, respectively.

[0092] The peripheral constraint member is a constraint sleeve formed by the combination of the peripheral constraint steel pipe 4 and the inner filled concrete 6. The peripheral constraint member functions to constrain the lateral displacement of the core energy consumption structure and prevent the core energy consumption structure from buckling. There is a layer of unbonding material between the peripheral constraint member and the core energy consumption structure to eliminate the adhesion friction therebetween.

[0093] After assembly, the front view, top view and cross-sectional view along the A-A plane of the buckling-restrained energy dissipation support are shown in Figures 12, 13 and 14, respectively.

[0094] When the cyclic deformation loading frequency is 0.2 Hz, the above buckling-restrained energy dissipation support is subjected to periodic alternating tensile-compression for 3 cycles at a displacement of 5.8 mm, 3 cycles at a displacement of 10 mm, 3 cycles at a displacement of 19.5 mm, 30 cycles at a displacement of 28.7 mm and 24 cycles at a displacement of 35 mm, respectively, without fatigue failure and with the maximum bearing capacity almost unchanged (28.7 mm working displacement is equivalent to 1 / 70 of the axial length of the buckling-restrained energy dissipation support), so the ultimate allowable displacement of the buckling-restrained energy dissipation support is much greater than 28.7 mm. Figure 15 shows the hysteresis curve of the buckling-restrained energy dissipation support subjected to tensile-compression cyclic plastic deformation. The elastic stiffness is obtained from the unloading segment of the 28.7 mm displacement hysteresis curve, and then the calculated yield displacement is about 3.0 mm. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e., the ductility coefficient) of the buckling-restrained energy dissipation support is much greater than 9.5.

[0095] In this embodiment, the yield strength of the second steel plate material is less than 180 MPa, the ratio of the ultimate allowable displacement of the buckling-restrained energy dissipation brace to the calculated yield displacement is greater than 9, and the ultimate allowable displacement is greater than 1 / 70 of the axial length of the buckling-restrained energy dissipation brace; and under this ultimate allowable displacement condition, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the load-carrying capacity attenuation is less than 15%.

[0096] Embodiment 2:

[0097] A buckling-restrained energy dissipation brace, a manufacturing method, and geometrical shape and size, a first steel plate material, and a second steel plate material are the same as those of Embodiment 1.

[0098] Under the cyclic deformation loading frequency of 1.75 Hz, the buckling-restrained energy dissipation brace is subjected to 3 cycles of periodic alternating tensile-compressive deformation at a displacement of 5.5 mm, 3 cycles of periodic alternating tensile-compressive deformation at a displacement of 8.5 mm, 3 cycles of periodic alternating tensile-compressive deformation at a displacement of 18 mm, 30 cycles of periodic alternating tensile-compressive deformation at a displacement of 28.8 mm, and 14 cycles of periodic alternating tensile-compressive deformation at a displacement of 34 mm, respectively, and still does not fail and the maximum load-carrying capacity remains almost unchanged (28.8 mm working displacement is equivalent to 1 / 70 of the axial length of the buckling-restrained energy dissipation brace), so the ultimate allowable displacement of the buckling-restrained energy dissipation brace is much greater than 28.8 mm. The hysteresis curve of the buckling-restrained energy dissipation brace subjected to tensile-compressive cyclic plastic deformation is shown in FIG. 16. The elastic stiffness is obtained from the unloading segment of the 28.8 mm displacement hysteresis curve, and then the calculated yield displacement is about 3.0 mm. The ratio of the ultimate allowable displacement of the buckling-restrained energy dissipation brace to the calculated yield displacement (i.e., the ductility coefficient) is much greater than 9.6. When the tensile-compressive cyclic deformation displacement is 28.8 mm and the loading frequency is 1.75 Hz, the average rate of deformation of the buckling-restrained energy dissipation brace is 201.6 mm / s.

[0099] In this embodiment, the yield strength of the second steel plate material is less than 180 MPa, the ratio of the ultimate allowable displacement of the buckling-restrained energy dissipation brace to the calculated yield displacement is greater than 9, and the ultimate allowable displacement is greater than 1 / 70 of the axial length of the buckling-restrained energy dissipation brace; and under this ultimate allowable displacement condition, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the load-carrying capacity attenuation is less than 15%. The buckling-restrained energy dissipation brace can have good fatigue deformation capacity at high speed (or high strain rate).

[0100] Embodiments 3-4:

[0101] A buckling-restrained energy dissipation brace is composed of a core energy dissipation structure and a peripheral restraining member.

[0102] The cross section of the core energy dissipation structure has a cross-shaped axisymmetric geometry, the symmetry axis of which is the axial direction of the buckling-restrained energy dissipation brace, and the cross section is narrow in the middle and wide at both ends along the axial direction. The geometry and size of the two types of steel plates, the preparation method and geometry and size of the core energy dissipation structure, and the manufacturing method and geometry and size of the buckling-restrained energy dissipation brace are the same as those of Embodiment 1, and are specifically shown in Figs. 1 and 2, Figs. 4 and 5, Figs. 9-11, Figs. 12-14. The thicknesses of the first steel plate and the second steel plate are the same, both being 16 mm. The ratio of the sum of the cross-sectional areas of the two second steel plate core energy dissipation segments to the cross-sectional area of the first steel plate core energy dissipation segment is 1.0. After welding and assembly, the product of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welding side of the second steel plate core energy dissipation segment (i.e., half the width w0 of the second steel plate core energy dissipation segment) and the thickness (t) of the second steel plate is 0.5 times the cross-sectional area (W0T) of the core energy dissipation segment of the adjacent first steel plate. The ratio of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welding side of the second steel plate core energy dissipation segment to the thickness of the second steel plate is about 4.7. The total length of the buckling-restrained energy dissipation brace is 2000 mm.

[0103] The chemical compositions (the steel inevitably contains trace amounts of P, S, N and other impurity elements), mechanical properties (including yield strength, elongation after fracture and room temperature fatigue life; the test conditions for material fatigue life are strain amplitude 1%, loading frequency 0.2 Hz and strain ratio -1) and main microstructure characteristics of the two types of steel plate materials are listed in Table 1. The microstructure of the first steel plate material mainly contains ferrite structure with a volume fraction of not less than 85% (when the microstructure of the first steel plate material is not entirely ferrite structure, the remaining structure is one or more than one of α' martensite or carbide), and the average size of the ferrite grains is not greater than 200 μm. The microstructure of the second steel plate material is ferrite and carbide with a volume fraction of not more than 6%, and the average size of the ferrite grains is not greater than 200 μm.

[0104] In Embodiments 3 and 4, the yield strength and plastic deformation flow stress of the first steel plate material are greater than those of the second steel plate material, and the yield strength of the first steel plate material is greater than that of the second steel plate material by more than 40 MPa; in the deformation strengthening stage, when the true strain is not greater than 0.12, the plastic deformation work hardening rate of the first steel plate material is not less than that of the second steel plate material. In addition, under the fatigue deformation loading conditions of strain amplitude 1%, loading frequency 0.1-0.2 Hz and strain ratio -1, the room temperature fatigue life of both the first steel plate material and the second steel plate material is not less than 500 cycles.

[0105] Table 1

[0106] The peripheral constraint member is a constraint sleeve formed by a steel pipe combined with inner filled concrete. There is a layer of unbonded material between the peripheral constraint member and the core energy dissipation structure.

[0107] In Example 3, the buckling-restrained energy dissipation brace did not fail and the maximum load capacity remained almost unchanged after 3 cycles of periodic alternating tension-compression with 10mm displacement and 32 cycles of periodic alternating tension-compression with 30mm displacement at the loading frequency of 0.2Hz (30mm working displacement is equivalent to 1 / 67 of the axial length of the buckling-restrained energy dissipation brace), so the ultimate allowable displacement of the buckling-restrained energy dissipation brace is greater than 30mm. The elastic stiffness is obtained from the unloading segment of the 30mm displacement hysteresis curve, and then the calculated yield displacement is about 3.6mm. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility factor) of the buckling-restrained energy dissipation brace is greater than 8.3.

[0108] In Example 4, the buckling-restrained energy dissipation brace did not fail and the maximum load capacity remained almost unchanged after 3 cycles of periodic alternating tension-compression with 10mm displacement and 32 cycles of periodic alternating tension-compression with 30.4mm displacement at the loading frequency of 0.2Hz (30.4mm working displacement is equivalent to 1 / 66 of the axial length of the buckling-restrained energy dissipation brace), so the ultimate allowable displacement of the buckling-restrained energy dissipation brace is greater than 30.4mm. The elastic stiffness is obtained from the unloading segment of the 30.4mm displacement hysteresis curve, and then the calculated yield displacement is about 3.8mm. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility factor) of the buckling-restrained energy dissipation brace is greater than 8.0.

[0109] In Example 3 and Example 4, the yield strength of the second steel plate material is between 180MPa and 300MPa, the ratio of the ultimate allowable displacement to the calculated yield displacement of the buckling-restrained energy dissipation brace is greater than 7, and the ultimate allowable displacement is greater than 1 / 80 of the axial length of the buckling-restrained energy dissipation brace; and under this ultimate allowable displacement condition, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tension-compression plastic deformation and the load capacity attenuation is less than 15%.

[0110] In Example 3 and Example 4, the calculated yield displacement, the ultimate allowable displacement, and the ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility factor) of the buckling-restrained energy dissipation brace are shown in Table 2.

[0111] Table 2

[0112] Examples 5-8:

[0113] A buckling-restrained energy dissipation brace is composed of a core energy dissipation structure and a peripheral constraint member.

[0114] The cross section of the core energy dissipation structure has a cross-shaped axisymmetric geometry, the symmetry axis of which is the axial direction of the buckling-restrained energy dissipation brace, and the cross section is narrow in the middle and wide at both ends along the axial direction. The core energy dissipation structure is composed of one first steel plate and two second steel plates; the two second steel plates are respectively arranged above and below the first steel plate, with the longitudinal center line of the first steel plate as the symmetry axis; the two second steel plates are tightly connected with the first steel plate by welding, and the welds are parallel to the axial direction of the core energy dissipation structure and the buckling-restrained energy dissipation brace. The geometric shapes of the two types of steel plates, the preparation method and geometric shape of the core energy dissipation structure, and the manufacturing method and geometric shape of the buckling-restrained energy dissipation brace are shown in FIGS. 1 and 2, FIGS. 4 and 5, FIGS. 9-11, and FIGS. 12-14, respectively. The core energy dissipation segment length of the first steel plate and the second steel plate is L0=l0=1530mm, and the total length of the first steel plate and the second steel plate (i.e. the total length of the buckling-restrained energy dissipation brace) is 2000mm.

[0115] In Examples 5-8, the first steel plate material constituting the core energy dissipation structure is the same, and the second steel plate material constituting the core energy dissipation structure is also the same. The chemical composition and mass percentage of the first steel plate material are: 0.54% Mn, 0.16% Si, 0.19% C, 0.013% P, 0.006% S, 0.006% N, and the rest is Fe and inevitable impurity elements. The yield strength of the first steel plate material is 282MPa, and the elongation after fracture is 36%. Under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.2Hz, and a strain ratio of -1, the room temperature fatigue life of the first steel plate material is about 1000 cycles. The microstructure of the first steel plate material is mainly ferrite structure (ferrite matrix containing carbides with a volume fraction of not more than 6%), and the average ferrite grain size is about 50μm.

[0116] The chemical composition and mass percentage of the second steel plate material are: 0.08% Mn, less than 0.02% Si, 0.003% C, 0.01% P, 0.015% S, 0.005% N, and the rest is Fe and inevitable impurity elements. The yield strength of the second steel plate material is 153MPa, and the elongation after fracture is 48%. Under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.2Hz, and a strain ratio of -1, the room temperature fatigue life of the second steel plate material is about 1300 cycles. The microstructure of the second steel plate material is ferrite structure, and the average ferrite grain size is about 50μm.

[0117] The yield strength and plastic deformation flow stress of the first steel plate material are greater than the yield strength and plastic deformation flow stress of the second steel plate material respectively, and the yield strength of the first steel plate material is 129 MPa greater than the yield strength of the second steel plate material; in the deformation strengthening stage, when the true strain is not greater than 0.12, the plastic deformation work hardening rate of the first steel plate material is not less than the plastic deformation work hardening rate of the second steel plate material. In addition, under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.1-0.2 Hz and a strain ratio of -1, the room temperature fatigue life of the first steel plate material and the second steel plate material is not less than 500 cycles.

[0118] Other geometric dimensions of the first steel plate and the second steel plate are listed in Table 3. The main geometric characteristics of the core energy dissipation structure, including the ratio of the thickness of the first steel plate to the thickness of the second steel plate (T / t), the ratio of the sum of the cross-sectional areas of the two second steel plate core energy dissipation segments to the cross-sectional area of the first steel plate core energy dissipation segment (2·(w0 / 2)·t / W0·T), the product of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welded side of the second steel plate core energy dissipation segment (i.e. the width w0 / 2 of the second steel plate core energy dissipation segment) to the thickness of the second steel plate (t) relative to the cross-sectional area of the adjacent connected first steel plate core energy dissipation segment (W0T) ((w0 / 2)·t / W0·T), and the ratio of the distance from the connecting weld between the second steel plate and the adjacent first steel plate to the non-welded side of the second steel plate core energy dissipation segment to the thickness of the second steel plate (w0 / 2 / t) are also listed in Table 3.

[0119] Table 3

[0120] As can be seen from Table 3, in Examples 5-8, the geometric dimensions of the first steel plate and the second steel plate and the correlation between the related geometric dimensions meet the various requirements of the present application, i.e. the thickness of the first steel plate is more than 0.5 times the thickness of the second steel plate; the ratio of the sum of the cross-sectional areas of all second steel plate core energy dissipation segments to the sum of the cross-sectional areas of all first steel plate core energy dissipation segments is not less than 0.6; the product of the distance from the connecting weld between the two types of steel plates to the non-welded side of the second steel plate core energy dissipation segment to the thickness of the second steel plate is 2.5 times or less the cross-sectional area of the first steel plate core energy dissipation segment; and the ratio of the distance from the connecting weld between the two types of steel plates to the non-welded side of the second steel plate core energy dissipation segment to the thickness of the second steel plate is not greater than 20.

[0121] The peripheral constraint member is a constraint sleeve formed by a steel pipe combined with inner filled concrete. There is a layer of unbonding material between the peripheral constraint member and the core energy dissipation structure.

[0122] In Example 5, the buckling-restrained energy-dissipating brace did not fail and the maximum load capacity remained almost unchanged after being subjected to 3 cycles of alternating tension-compression with 10 mm displacement, 3 cycles of alternating tension-compression with 20 mm displacement, and 32 cycles of alternating tension-compression with 28.7 mm displacement (28.7 mm working displacement is equivalent to 1 / 70 of the axial length of the buckling-restrained energy-dissipating brace), and thus the ultimate allowable displacement of the buckling-restrained energy-dissipating brace is greater than 28.7 mm. The calculated yield displacement is about 3.0 mm from the 28.7 mm displacement hysteresis curve. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e., the ductility factor) of the buckling-restrained energy-dissipating brace is greater than 9.5.

[0123] In Example 6, the buckling-restrained energy-dissipating brace did not fail and the maximum load capacity remained almost unchanged after being subjected to 3 cycles of alternating tension-compression with 10 mm displacement, and 33 cycles of alternating tension-compression with 29.4 mm displacement (29.4 mm working displacement is equivalent to 1 / 68 of the axial length of the buckling-restrained energy-dissipating brace), and thus the ultimate allowable displacement of the buckling-restrained energy-dissipating brace is greater than 29.4 mm. The calculated yield displacement is about 3.2 mm from the 29.4 mm displacement hysteresis curve. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e., the ductility factor) of the buckling-restrained energy-dissipating brace is greater than 9.1.

[0124] In Example 7, the buckling-restrained energy-dissipating brace did not fail and the maximum load capacity remained almost unchanged after being subjected to 3 cycles of alternating tension-compression with 10.4 mm displacement, and 32 cycles of alternating tension-compression with 28.7 mm displacement (28.7 mm working displacement is equivalent to 1 / 70 of the axial length of the buckling-restrained energy-dissipating brace), and thus the ultimate allowable displacement of the buckling-restrained energy-dissipating brace is greater than 28.7 mm. The calculated yield displacement is about 3.0 mm from the 28.7 mm displacement hysteresis curve. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e., the ductility factor) of the buckling-restrained energy-dissipating brace is greater than 9.5.

[0125] In Example 8, the buckling-restrained energy-dissipating brace did not fail and the maximum load capacity remained almost unchanged after being subjected to 34 cycles of alternating tension-compression with 29.1 mm displacement (29.1 mm working displacement is equivalent to 1 / 69 of the axial length of the buckling-restrained energy-dissipating brace), and thus the ultimate allowable displacement of the buckling-restrained energy-dissipating brace is greater than 29.1 mm. The calculated yield displacement is about 3.0 mm from the 29.1 mm displacement hysteresis curve. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e., the ductility factor) of the buckling-restrained energy-dissipating brace is greater than 9.7.

[0126] In the above examples, the calculated yield displacement, the ultimate allowable displacement, and the ratio of the ultimate allowable displacement to the calculated yield displacement (i.e., the ductility factor) of the buckling-restrained energy-dissipating brace are shown in Table 4.

[0127] Table 4

[0128] In the above embodiments, the yield strength of the second steel plate material is less than 180 MPa, the ratio of the ultimate allowable displacement of the buckling-restrained energy-dissipating brace to the calculated yield displacement is greater than 9, and the ultimate allowable displacement is greater than 1 / 70 of the axial length of the buckling-restrained energy-dissipating brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy-dissipating brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the load carrying capacity attenuation is less than 15%.

[0129] Embodiments 9-12:

[0130] A buckling-restrained energy-dissipating brace is composed of a core energy-dissipating structure and a peripheral restraining member.

[0131] The core energy-dissipating structure is composed of one first steel plate and one second steel plate, and the first steel plate and the second steel plate have the same longitudinal length; the second steel plate is placed perpendicular to the first steel plate; the second steel plate is tightly connected to the first steel plate by welding, the welding seam is parallel to the axial direction of the buckling-restrained energy-dissipating brace, and the connecting welding seam is located on the first steel plate (i.e., the connecting welding seam is located between the two sides of the first steel plate).

[0132] The geometric shape of the first steel plate is shown in FIG. 4. The total length of the first steel plate L = 2000 mm; the length of the core energy-dissipating segment of the first steel plate L0= 1530 mm, and the width W0= 75 mm; the thickness of the first steel plate T = 16 mm.

[0133] The geometric shape of the second steel plate is shown in FIG. 5. The total length of the second steel plate l = 2000 mm; the length of the core energy-dissipating segment of the second steel plate l0= 1530 mm, and the width w0 / 2 = 75 mm; the thickness of the second steel plate t = 16 mm.

[0134] The ratio of the thickness of the first steel plate to the thickness of the second steel plate is 1.0; the ratio of the cross-sectional area of the core energy-dissipating segment of the second steel plate to the cross-sectional area of the core energy-dissipating segment of the first steel plate is 1.0; the product of the distance from the connecting welding seam between the two adjacent steel plates to the non-welding side of the core energy-dissipating segment of the second steel plate and the thickness of the second steel plate is 1 times the cross-sectional area of the core energy-dissipating segment of the adjacent first steel plate (i.e., the same as the front and back); and the ratio of the distance from the connecting welding seam between the second steel plate and the adjacent first steel plate to the non-welding side of the core energy-dissipating segment of the second steel plate to the thickness of the second steel plate is 4.7.

[0135] The chemical compositions (the inevitable trace amounts of P, S, N and other impurities in the steel), mechanical properties (including yield strength, elongation after fracture and fatigue life at room temperature; the test conditions for the fatigue life of the material are strain amplitude 1%, loading frequency 0.2 Hz and strain ratio -1) and microstructure characteristics of the two types of steel plate materials are listed in Table 5. The microstructure of the first steel plate material mainly contains ferrite structure with a volume fraction of not less than 85% (when the microstructure of the first steel plate material is not entirely ferrite structure, the remaining structure is one or more than one of α' martensite or carbide), and the average size of the ferrite grains is not greater than 200 μm. The microstructure of the second steel plate material is ferrite and carbide with a volume fraction of not more than 6%, and the average size of the ferrite grains is not greater than 200 μm.

[0136] In Examples 9 to 12, the yield strength and plastic deformation flow stress of the first steel plate material are greater than those of the second steel plate material, and the yield strength of the first steel plate material is greater than that of the second steel plate material by more than 40 MPa; in the deformation strengthening stage, when the true strain is not greater than 0.12, the plastic deformation work hardening rate of the first steel plate material is not less than that of the second steel plate material. In addition, under the fatigue deformation loading conditions of strain amplitude 1%, loading frequency 0.1 to 0.2 Hz and strain ratio -1, the room temperature fatigue life of the first steel plate material and the second steel plate material are both not less than 500 cycles.

[0137] Table 5

[0138] The peripheral constraint member is a constraint sleeve formed by a combination of a steel pipe and inner filled concrete. There is a layer of unbonded material between the peripheral constraint member and the core energy dissipation structure.

[0139] In the above examples, at a loading frequency of 0.25 Hz, the calculated yield displacement, the ultimate allowable displacement, the ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility factor) of the buckling-restrained energy dissipation brace are shown in Table 6. Under the ultimate allowable displacement condition, the buckling-restrained energy dissipation brace all completed at least 30 cycles of cyclic tensile-compressive plastic deformation without fatigue failure, and the bearing capacity of the buckling-restrained energy dissipation brace did not attenuate.

[0140] Table 6

[0141] In the above embodiments, when the yield strength of the second steel plate material is between 180 MPa and 300 MPa, the ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility factor) of the buckling-restrained energy-dissipating brace is greater than 7, and the ultimate allowable displacement is not less than 1 / 80 (25 mm) of the length of the buckling-restrained energy-dissipating brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy-dissipating brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the load carrying capacity attenuation is less than 15%.

[0142] Embodiment 13:

[0143] A buckling-restrained energy-dissipating brace is composed of a core energy-dissipating structure and a peripheral restraining member.

[0144] The core energy-dissipating structure is composed of one first steel plate and one second steel plate, and the first steel plate and the second steel plate have the same longitudinal length; the second steel plate is placed perpendicularly to the first steel plate; the second steel plate is tightly connected to the first steel plate by welding, the welding seam is parallel to the axial direction of the buckling-restrained energy-dissipating brace, and the connecting welding seam is located on the first steel plate (i.e. the connecting welding seam is located between the two sides of the first steel plate).

[0145] The chemical composition and its mass percentage of the first steel plate material are: 0.27% Mn, 0.18% Si, 0.056% C, 0.01% P, 0.007% S, 0.006% N, and the rest is Fe and inevitable impurity elements. The yield strength of the first steel plate material is 189 MPa, and the elongation after fracture is 46%. Under the fatigue deformation loading condition of a strain amplitude of 1%, a loading frequency of 0.2 Hz, and a strain ratio of -1, the fatigue life of the first steel plate material at room temperature is about 1250 cycles. The microstructure of the first steel plate material is mainly ferrite structure (the ferrite matrix contains carbides with a volume fraction of not more than 4%), and the average ferrite grain size is about 41 μm.

[0146] The chemical composition and its mass percentage of the second steel plate material are: 0.03% Mn, 0.01% Si, 0.004% C, 0.02% Ti, 0.007% P, 0.011% S, 0.005% N, and the rest is Fe and inevitable impurity elements. The yield strength of the second steel plate material is 125 MPa, and the elongation after fracture is 52%. Under the fatigue deformation loading condition of a strain amplitude of 1%, a loading frequency of 0.2 Hz, and a strain ratio of -1, the fatigue life of the second steel plate material at room temperature is about 730 cycles. The microstructure of the second steel plate material is ferrite structure, and the average ferrite grain size is about 54 μm.

[0147] The yield strength and plastic deformation flow stress of the first steel plate material are greater than the yield strength and plastic deformation flow stress of the second steel plate material respectively, and the yield strength of the first steel plate material is 64 MPa greater than the yield strength of the second steel plate material; in the deformation strengthening stage, when the true strain is not greater than 0.12, the plastic deformation work hardening rate of the first steel plate material is not less than the plastic deformation work hardening rate of the second steel plate material. In addition, under the fatigue deformation loading conditions of strain amplitude 1%, loading frequency 0.1-0.2 Hz and strain ratio-1, the room temperature fatigue life of the first steel plate material and the second steel plate material is not less than 500 cycles.

[0148] The geometric shape of the first steel plate is shown in Fig. 4. The total length of the first steel plate L = 2000 mm; the length of the core energy dissipation section of the first steel plate L0= 1530 mm, the width W0= 75 mm; the thickness of the first steel plate T = 16 mm.

[0149] The geometric shape of the second steel plate is shown in Fig. 5. The total length of the second steel plate l = 2000 mm; the length of the core energy dissipation section of the second steel plate l0= 1530 mm, the width w0 / 2 = 75 mm; the thickness of the second steel plate t = 16 mm.

[0150] The ratio of the thickness of the first steel plate to the thickness of the second steel plate is 1.0; the ratio of the cross-sectional area of the core energy dissipation section of the second steel plate to the cross-sectional area of the core energy dissipation section of the first steel plate is 1.0; the product of the distance from the connecting weld between the two types of steel plates connected adjacently to the non-welding side of the core energy dissipation section of the second steel plate and the thickness of the second steel plate is 1 times the cross-sectional area of the core energy dissipation section of the first steel plate connected adjacently (i.e. the same as the former); the ratio of the distance from the connecting weld between the second steel plate and the adjacent first steel plate to the non-welding side of the core energy dissipation section of the second steel plate to the thickness of the second steel plate is 4.7.

[0151] The peripheral constraint member is a constraint sleeve formed by a peripheral constraint steel pipe combined with inner filled concrete. There is a layer of unbonding material between the peripheral constraint member and the core energy dissipation structure.

[0152] When the cyclic deformation loading frequency is 0.2 Hz, the buckling-restrained energy dissipation brace described above does not fail and the maximum bearing capacity remains almost unchanged (29.2 mm working displacement is equivalent to 1 / 69 of the axial length of the buckling-restrained energy dissipation brace) after 3 cycles of periodic alternating tension-compression with 10 mm displacement and 32 cycles of periodic alternating tension-compression with 29.2 mm displacement, so the ultimate allowable displacement of the buckling-restrained energy dissipation brace is greater than 29.2 mm. The elastic stiffness is obtained from the unloading segment of the 29.2 mm displacement hysteresis curve, and then the calculated yield displacement is about 2.8 mm. The ratio of the ultimate allowable displacement of the buckling-restrained energy dissipation brace to the calculated yield displacement (i.e. the ductility coefficient) is greater than 10.4.

[0153] In this embodiment, the yield strength of the second steel plate material is less than 180 MPa, the ratio of the ultimate allowable displacement of the buckling-restrained energy-dissipating brace to the calculated yield displacement is greater than 9, and the ultimate allowable displacement is greater than 1 / 70 of the axial length of the buckling-restrained energy-dissipating brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy-dissipating brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the load carrying capacity attenuation is less than 15%.

[0154] Comparative Example 1

[0155] A buckling-restrained energy-dissipating brace is composed of a core energy-dissipating structure and a peripheral restraint member. The cross section of the core energy-dissipating structure has a cruciform axisymmetric geometry, the axis of symmetry being the axial direction of the energy-dissipating brace, and the cross section is narrow in the middle and wide at both ends along the axial direction. Specifically, the core energy-dissipating structure is composed of one wide steel plate and two narrow steel plates, the three steel plates having the same length in the longitudinal direction; the two narrow steel plates are respectively arranged above and below the wide steel plate, with the longitudinal center line of the wide steel plate as the axis of symmetry; and the three steel plates are tightly connected by welding, and the welds are parallel to the axial direction of the buckling-restrained energy-dissipating brace.

[0156] The geometry of the wide steel plate is shown in FIG. 4, the total length of the wide steel plate L = 2000 mm, the length of the core energy-dissipating segment L0= 1530 mm, the width W0= 150 mm, and the thickness of the steel plate T = 16 mm. The geometry of the narrow steel plate is shown in FIG. 5, the total length of the narrow steel plate l = 2000 mm, the length of the core energy-dissipating segment l0= 1530 mm, the width w0 / 2 = 75 mm, and the thickness of the steel plate t = 16 mm.

[0157] The wide and narrow steel plates are of the same material, and the chemical composition by mass percentage is: 0.08% Mn, less than 0.02% Si, 0.003% C, 0.01% P, 0.015% S, 0.005% N, and the rest is Fe and unavoidable impurity elements. The yield strength of the steel plate material is 153 MPa, and the elongation after fracture is 48%. Under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.2 Hz, and a strain ratio of -1, the room temperature fatigue life of the steel plate material is about 1300 cycles. The microstructure of the steel plate material is ferrite structure, and the average ferrite grain size is about 50 μm.

[0158] The peripheral restraint member is a restraint sleeve formed by a steel pipe combined with inner filled concrete. There is a layer of unbonding material between the peripheral restraint member and the core energy-dissipating structure.

[0159] The buckling-restrained energy dissipation brace failed in fatigue at 24 cycles of alternating tensile-compressive deformation with 25 mm displacement at loading frequency of 0.2 Hz. The 25 mm working displacement is equivalent to 1 / 80 of the total length of the brace. Therefore, the limit allowable displacement of the buckling-restrained energy dissipation brace of the present comparative example is less than 25 mm, i.e. less than 1 / 80 of the axial length of the core energy dissipation structure.

[0160] Comparative Example 2

[0161] A buckling-restrained energy dissipation brace is composed of a core energy dissipation structure and a peripheral restraining member. The core energy dissipation structure is composed of one first steel plate and one second steel plate, the first steel plate and the second steel plate have the same length along the longitudinal direction; the second steel plate is placed perpendicularly to the first steel plate; the second steel plate is connected to the first steel plate by welding, the welding seam is parallel to the axial direction of the buckling-restrained energy dissipation brace, and the connecting welding seam is located on the first steel plate (i.e. the connecting welding seam is located between the two sides of the first steel plate).

[0162] The geometry of the first steel plate is shown in Figure 4, the total length of the first steel plate L = 2000 mm, the length of the core energy dissipation segment L0= 1530 mm, the width W0= 75 mm, and the thickness of the first steel plate T = 16 mm. The geometry of the second steel plate is shown in Figure 5, the total length of the second steel plate l = 2000 mm, the length of the core energy dissipation segment l0= 1530 mm, the width w0 / 2 = 75 mm, and the thickness of the second steel plate t = 16 mm.

[0163] The ratio of the thickness of the first steel plate to the thickness of the second steel plate is 1.0; the ratio of the cross-sectional area of the core energy dissipation segment of the second steel plate to the cross-sectional area of the core energy dissipation segment of the first steel plate is 1.0; the product of the distance from the connecting welding seam between the two types of steel plates to the non-welding side of the core energy dissipation segment of the second steel plate and the thickness of the second steel plate is 1 times the cross-sectional area of the core energy dissipation segment of the first steel plate (i.e. the same as the front and back); the ratio of the distance from the connecting welding seam between the second steel plate and the adjacent first steel plate to the non-welding side of the core energy dissipation segment of the second steel plate to the thickness of the second steel plate is 4.7.

[0164] The chemical composition and its mass percentage of the first steel plate material are: 1.25% Mn, 0.44% Si, 0.20% C, 0.012% P, 0.008% S, 0.01% N, and the rest is Fe and unavoidable impurity elements. The yield strength of the first steel plate material is 376 MPa, and the elongation after fracture is 22% (less than the minimum required value of 26% specified in the present application); under the fatigue deformation loading condition of strain amplitude 1%, loading frequency 0.2 Hz, and strain ratio -1, the room temperature fatigue life of the first steel plate material is about 410 cycles (less than the minimum required value of 500 cycles specified in the present application). The microstructure of the steel plate is mainly ferrite structure, and the average ferrite grain size is 52 μm.

[0165] The second steel plate material has the following chemical composition and mass percentage: 0.08% Mn, less than 0.02% Si, 0.003% C, 0.01% P, 0.015% S, 0.005% N, and the balance of Fe and inevitable impurities. The yield strength of the second steel plate material is 153 MPa, and the elongation after fracture is 48%. The fatigue life of the second steel plate material at room temperature is about 1300 cycles under the fatigue deformation loading condition of strain amplitude 1%, loading frequency 0.2 Hz, and strain ratio -1. The microstructure of the second steel plate material is ferrite, and the average ferrite grain size is about 50 μm.

[0166] The peripheral constraint member is a constraint sleeve formed by a steel pipe combined with inner filled concrete. There is a layer of unbonded material between the peripheral constraint member and the core energy dissipation structure.

[0167] The buckling-restrained energy dissipation brace is subjected to fatigue failure after 22 cycles of alternating tension-compression at a displacement of 28.6 mm, but it can be subjected to fatigue failure after about 30 cycles of alternating tension-compression at a displacement of 25 mm. Therefore, the ultimate allowable displacement of the buckling-restrained energy dissipation brace is about 25 mm (corresponding to 1 / 80 of the length of the buckling-restrained energy dissipation brace). The calculated yield displacement is about 3.2 mm according to the hysteresis curve at a displacement of 25 mm. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility coefficient) of the buckling-restrained energy dissipation brace is about 7.8. In the present comparative example, although the yield strength of the second steel plate material is less than 180 MPa, the ratio of the ultimate allowable displacement to the calculated yield displacement of the buckling-restrained energy dissipation brace is less than 9, and the ultimate allowable displacement is not more than 1 / 70 of the axial length of the buckling-restrained energy dissipation brace.

[0168] Comparative Example 3:

[0169] A buckling-restrained energy dissipation brace is composed of a core energy dissipation structure and a peripheral restraining member. The cross section of the core energy dissipation structure has a cross-shaped axisymmetric geometry, with the axis of symmetry being the axial direction of the buckling-restrained energy dissipation brace, and the cross section being narrow in the middle and wide at both ends along the axial direction. The core energy dissipation structure is composed of a first steel plate and a second steel plate. The geometry and size of the two types of steel plates, the preparation method and geometry and size of the core energy dissipation structure, and the manufacturing method and geometry and size of the buckling-restrained energy dissipation brace are the same as those of Embodiment 1. The thicknesses of the first steel plate and the second steel plate are the same, both being 16 mm. The ratio of the sum of the cross-sectional areas of the two core energy dissipation segments of the second steel plate to the cross-sectional area of the core energy dissipation segment of the first steel plate is 1.0. After welding and assembly, the product of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welding side of the core energy dissipation segment of the second steel plate (i.e., half the width w0 of the core energy dissipation segment of the second steel plate) and the thickness (t) of the second steel plate is 0.5 times the cross-sectional area (W0T) of the core energy dissipation segment of the first steel plate adjacent to the connecting weld. The ratio of the distance from the connecting weld between the second steel plate and the first steel plate to the non-welding side of the core energy dissipation segment of the second steel plate to the thickness of the second steel plate is 4.7. The total length of the buckling-restrained energy dissipation brace is 2000 mm.

[0170] The chemical composition and mass percentage of the first steel plate material are: 1.29% Mn, 0.62% Si, 0.27% C, 0.01% P, 0.008% S, 0.012% N, and the balance of Fe and inevitable impurity elements. The yield strength of the first steel plate material is 412 MPa, and the elongation after fracture is 25%. Under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.2 Hz, and a strain ratio of -1, the room temperature fatigue life of the first steel plate material is 452 cycles. The microstructure of the steel plate is mainly ferrite structure, and the average ferrite grain size is 48 μm. The C content, yield strength, elongation after fracture, and fatigue life of the first steel plate material do not meet the specified values of the present application.

[0171] The chemical composition and mass percentage of the second steel plate material are: 0.9% Mn, 0.2% Si, 0.16% C, 0.05% V, 0.01% P, 0.008% S, 0.01% N, and the balance of Fe and inevitable impurity elements. The yield strength of the second steel plate material is 316 MPa, and the elongation after fracture is 28%. Under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.2 Hz, and a strain ratio of -1, the room temperature fatigue life of the second steel plate material is about 670 cycles. The microstructure of the second steel plate material is mainly ferrite structure, and the average ferrite grain size is 52 μm. The yield strength of the second steel plate material does not meet the specified value of the present application.

[0172] The peripheral constraint member is a constraint sleeve formed by a steel tube combined with inner filled concrete. There is a layer of unbonded material between the peripheral constraint member and the core energy dissipation structure.

[0173] The buckling-restrained energy dissipation brace failed in fatigue after 30 cycles of alternating tensile-compressive plastic deformation with a displacement of 25.4 mm. Therefore, the ultimate allowable displacement of the buckling-restrained energy dissipation brace is about 25.4 mm. The displacement of 25.4 mm is equivalent to 1 / 79 of the length of the buckling-restrained energy dissipation brace. The calculated yield displacement is 3.9 mm from the hysteresis curve of the displacement of 25.4 mm. The ratio of the ultimate allowable displacement to the calculated yield displacement (i.e. the ductility factor) of the buckling-restrained energy dissipation brace is about 6.5 (less than 7).

[0174] In the present comparative example, although the buckling-restrained energy dissipation brace can complete 30 cycles of alternating tensile-compressive plastic deformation with a displacement of about 1 / 80 of the total length of the brace, the ductility factor of the buckling-restrained energy dissipation brace is less than 7.

[0175] The foregoing description of the examples has been presented for the purposes of illustration and description. It is apparent to those skilled in the art that modifications can be made to the examples without departing from the scope of the application. It is intended that changes to the examples come within the scope of the application. Accordingly, the application is not limited to the examples described above, but extends to any changes or modifications within the scope of the present application, as encompassed by the appended claims.

Claims

1. A low-cost high-ductility anti-fatigue core energy dissipation structure for buckling-restrained energy dissipation brace, which plays a role in absorbing external vibration energy when the buckling-restrained energy dissipation brace is subjected to cyclic alternating tensile-compressive plastic deformation, characterized in that the low-cost high-ductility anti-fatigue core energy dissipation structure comprises at least a first steel plate and a second steel plate, the second steel plate must be and can only be adjacent to the first steel plate and connected by welding, and the connecting weld between the first steel plate and the second steel plate is parallel to the axial direction of the core energy dissipation structure; the yield strength and plastic deformation flow stress of the material of the first steel plate are greater than the yield strength and plastic deformation flow stress of the material of the second steel plate respectively, and the yield strength of the material of the first steel plate is greater than the yield strength of the material of the second steel plate by more than 40 MPa; the plastic deformation work hardening rate of the material of the first steel plate is not less than the plastic deformation work hardening rate of the material of the second steel plate when the true strain is not greater than 0.12 in the plastic deformation strengthening stage; the room temperature fatigue life of the material of the first steel plate and the material of the second steel plate is not less than 500 cycles under the fatigue deformation loading conditions of a strain amplitude of 1%, a loading frequency of 0.1-0.2 Hz, and a strain ratio of -1; the chemical composition of the material of the first steel plate is 0.05%≤C≤0.25%, Mn≤1.8%, Si≤1.0%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest is Fe and inevitable impurity elements; the yield strength of the material of the first steel plate is between 180 MPa and 400 MPa, and the elongation after fracture is not less than 26%; the microstructure of the material of the first steel plate comprises ferrite structure with a volume fraction of not less than 85%, and the average size of ferrite grains is not greater than 200 μm; when the microstructure of the material of the first steel plate is not entirely ferrite structure, the remaining structure is one or more than one of α' martensite or carbide; the chemical composition of the material of the second steel plate is C≤0.22%, Mn≤1.5%, Si≤0.8%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest is Fe and inevitable impurity elements; the yield strength of the material of the second steel plate is not greater than 300 MPa, and the elongation after fracture is not less than 28%; the microstructure of the material of the second steel plate is ferrite and carbide with a volume fraction of not more than 6%, and the average size of ferrite grains is not greater than 200 μm; the thickness of the first steel plate is more than 0.5 times the thickness of the second steel plate; in the low-cost high-ductility anti-fatigue core energy dissipation structure, the ratio of the sum of the cross-sectional areas of all the second steel plate core energy dissipation segments to the sum of the cross-sectional areas of all the first steel plate core energy dissipation segments is not less than 0.

6. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ When the second steel plate is connected to the first steel plate on both sides, the ratio of the distance between the connecting welds of the two types of steel plates to the thickness of the second steel plate is not greater than 20. When the second steel plate is connected to the first steel plate on both sides, the ratio of the cross-sectional area of the core energy dissipation section of the second steel plate to the cross-sectional area of the core energy dissipation section of any of the adjacent first steel plates is not greater than 5.

0.

2. The low cost high ductility fatigue resistant core energy dissipation structure of claim 1, wherein, When the second steel plate is connected to the first steel plate on both sides, the distance between the welds on both sides of the second steel plate is not greater than 80 times the thickness of the second steel plate.

3. The low-cost, high-ductility, fatigue-resistant core energy dissipation structure of any one of claims 1-2, wherein, The chemical composition of the first steel plate material further comprises one or more of Ti, Nb, and V; the mass percentage of the chemical composition of the first steel plate material is: 0.05%≤C≤0.25%, Mn≤1.8%, Si≤1.0%, Ti≤0.1%, Nb≤0.1%, V≤0.15%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest is Fe and unavoidable impurities.

4. The low cost, high ductility, fatigue resistant core energy dissipating structure of any one of claims 1-2, wherein, The chemical composition of the second steel plate material further comprises one or more of Ti, Nb, and V; the mass percentage of the chemical composition of the second steel plate material is: C≤0.22%, Mn≤1.5%, Si≤0.8%, Ti≤0.08%, Nb≤0.08%, V≤0.1%, P≤0.045%, S≤0.03%, N≤0.03%, and the rest is Fe and unavoidable impurities.

5. The low cost, high ductility, fatigue resistant core energy dissipating structure of any one of claims 1-2, wherein, If the cross-sectional geometry of the first steel plate or the second steel plate remains unchanged along the length direction, the core energy dissipation section of the first steel plate or the second steel plate is the full length of the first steel plate or the second steel plate. If the cross-sectional geometry of the first steel plate or the second steel plate presents the feature of being wide at both ends and narrow in the middle along the length direction, the core energy dissipation section of the first steel plate or the second steel plate is the narrow part in the middle of the first steel plate or the second steel plate.

6. The low cost, high ductility, fatigue resistant core energy dissipating structure of any one of claims 1-2, wherein, The cross-section of the core energy dissipation structure is selected to be an axisymmetric geometric shape.

7. A buckling-restrained energy dissipation brace, characterized by, The low-cost high-ductility fatigue-resistant core energy dissipation structure and the peripheral constraint member according to any one of claims 1-6, wherein the peripheral constraint member functions to constrain the lateral displacement of the core energy dissipation structure and prevent the core energy dissipation structure from buckling.

8. The buckling-restrained energy dissipation brace of claim 7, wherein, The peripheral constraint member is selected to be a constraint sleeve formed by a steel pipe combined with inner filled concrete, a reinforced concrete constraint sleeve, or a pure steel type structure constraint.

9. The buckling-restrained energy-dissipating brace according to claim 7, wherein When the yield strength of the second steel plate material is less than or equal to 180 MPa, the ratio of the ultimate allowable displacement to the calculated yield displacement of the buckling-restrained energy dissipation brace is not less than 9, and the ultimate allowable displacement is not less than 1 / 70 of the length of the buckling-restrained energy dissipation brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the bearing capacity attenuation is less than 15%; When the yield strength of the second steel plate material is greater than 180 MPa and not greater than 300 MPa, the ratio of the ultimate allowable displacement to the calculated yield displacement of the buckling-restrained energy dissipation brace is not less than 7, and the ultimate allowable displacement is not less than 1 / 80 of the length of the buckling-restrained energy dissipation brace; and under the condition of the ultimate allowable displacement, the buckling-restrained energy dissipation brace can complete at least 30 cycles of periodic alternating tensile-compressive plastic deformation and the bearing capacity attenuation is less than 15%.

10. Use of the buckling-restrained energy dissipation brace according to any one of claims 7 to 9, characterized in that, The buckling-restrained energy dissipation brace is installed in a building or structure and connected with the beam-column main structure of the building or structure to form an integral whole, thereby playing a role in dissipating external vibration energy.

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