High ductility fracture-free double-yield-point buckling-restrained brace with cross-shaped steel negative poisson's ratio core and multi-story fabricated building

Abstract

The application discloses a high-ductility fracture-free double-yield-point buckling-restrained brace with a cross-shaped steel negative Poisson's ratio core and a multi-storey or high-rise fabricated building, and the buckling-restrained brace comprises a cross-shaped steel first-order core, a corner steel second-order core, and corner steel peripheral constraints; the cross-shaped steel first-order core comprises a middle negative Poisson's ratio weakening area one in the middle of the cross-shaped steel; the corner steel second-order core comprises a middle negative Poisson's ratio weakening area two in the middle of the corner steel; the corner steel peripheral constraints comprise a middle pre-tightening area in the middle of the corner steel; four groups of the corner steel second-order core are respectively arranged at four corners of the cross-shaped steel first-order core; four groups of the corner steel peripheral constraints are respectively arranged at peripheries of the four groups of the corner steel second-order core and are pre-tightened in the middle pre-tightening area; the cross-shaped steel first-order core can produce a first displacement longitudinal sliding relative to the corner steel second-order core; the corner steel second-order core can produce a second displacement longitudinal sliding relative to the corner steel peripheral constraints; and the second displacement is greater than the first displacement. The application aims to solve the problems of the buckling-restrained brace, such as insufficient ductility, easy fracture and limited energy dissipation of the core under an earthquake.

Description

Technical Field

[0001] This application relates to the field of building structure technology, especially prefabricated structures, specifically to a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cross-shaped steel negative Poisson's ratio core and prefabricated buildings for multi-story and high-rise buildings. Background Technology

[0002] The trend of modern industrialized construction is creating an increasing demand for prefabricated building structures. Prefabricated buildings offer numerous advantages, including rapid construction, easy quality control, and minimal environmental impact. In the field of building support structures, prefabricated buckling-restrained braces can be easily prefabricated in factories and then quickly assembled on-site. This method can significantly shorten the construction cycle and reduce the complexity of on-site construction.

[0003] Regarding the performance of building structures, especially prefabricated building structures, on the one hand, with the increasing demands for seismic and disaster resistance, research on highly ductile materials (structures) is receiving increasing attention. Traditional building materials (structures) are prone to fracture under large deformations, which is extremely detrimental to the structural safety under extreme disasters (such as strong earthquakes and strong winds). Highly ductile materials (structures), on the other hand, can maintain their integrity under large tensile or compressive deformations, avoiding sudden fractures that could lead to local or overall structural damage. This demand for such material (structural) properties has driven research and application of highly ductile fracture-resistant materials (structures) in the field of building structures.

[0004] On the other hand, yield point is a key indicator of a material's mechanical properties. Single-yield-point braces have only one yield point; once the yield strength is reached, they begin to dissipate energy through plastic deformation. Under strong earthquakes, single-yield-point braces will experience significant deformation beyond their yield point. If the structural design is inadequate, this can lead to brace failure and compromise structural safety. With the continuous development of engineering technology, the requirements for material properties are becoming increasingly complex and diverse. In some special engineering applications, single-yield-point braces cannot meet the demands. Therefore, double-yield-point braces have emerged, offering unique advantages in building structures. Double-yield-point braces have two yield stages, gradually yielding and dissipating energy under different stress levels. In minor and moderate earthquakes, double-yield-point braces first begin dissipating energy at a lower yield point, and in strong earthquakes, they can further dissipate energy at a higher yield point, resulting in a smoother and more continuous energy dissipation process. Compared to single-yield-point braces, double-yield-point braces have higher energy dissipation efficiency and can better control the phased energy dissipation of the structure, further controlling inter-story displacement.

[0005] To meet the performance and construction requirements of buckling-restrained braces in prefabricated buildings, based on the above research results, it is necessary to continue researching a new type of buckling-restrained brace to solve the problems of insufficient ductility and easy fracture of existing buckling-restrained braces under large deformations. Summary of the Invention

[0006] In view of the shortcomings of existing technologies, this application provides a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core and its application in multi-story and high-rise prefabricated buildings. The aim is to solve the problems of insufficient ductility, easy fracture, and limited energy dissipation in buckling-restrained braces during earthquakes, particularly in the core, and to improve the toughness of the component by addressing energy dissipation issues. Through innovative geometric design and material optimization, this brace significantly enhances its energy dissipation capacity, deformation performance, and structural stability.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0008] This application first provides a high-ductility, fracture-free, double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core, comprising: a first-order cruciform steel core, including a central negative Poisson's ratio weakening zone I formed within a predetermined length range in the middle of the steel, and end connection zones I on both sides; a second-order angle steel core, including a central negative Poisson's ratio weakening zone II formed within a predetermined length range in the middle of the steel, and end connection zones II at both ends; and an outer constraint of the angle steel, including a central pre-tightening zone formed within a predetermined length range in the middle of the angle steel, and end connection zones III at both ends; four sets of the second-order angle steel cores are respectively installed at the four corners of the first-order cruciform steel core, and four sets of the outer constraints of the angle steel are respectively installed around the four sets of the second-order angle steel cores and pre-tightened in the central pre-tightening zone; the first-order cruciform steel core is capable of longitudinal sliding with a first displacement relative to the second-order angle steel core, and the second-order angle steel core is capable of longitudinal sliding with a second displacement relative to the outer constraints of the angle steel, wherein the second displacement is greater than the first displacement.

[0009] The buckling-restrained brace provided in this application effectively overcomes the shortcomings of insufficient ductility in traditional prefabricated buckling-restrained brace systems by employing a double yield point design. Traditional prefabricated buckling-restrained braces typically suffer from poor ductility and the design limitation of a single yield point. Although single yield point braces can fully utilize their energy dissipation capacity during strong earthquakes, their design limitations may prevent them from providing sufficient energy dissipation capacity under seismic loads of different magnitudes. In contrast, the double yield point brace design can adjust the energy absorption mechanism according to changes in earthquake magnitude, thus adapting more flexibly to seismic loads of different magnitudes. This double yield point structure can utilize the effect of the lower yield point during smaller earthquakes, while providing additional energy absorption capacity through the higher yield point during stronger earthquakes, thereby improving the overall seismic performance and durability of the structure.

[0010] This application also provides a multi-story or high-rise prefabricated building, including the buckling-restrained brace.

[0011] The advantages of this application compared to the prior art are as follows: This application provides a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core, applicable to multi-story and high-rise prefabricated buildings. It aims to solve the problems of insufficient ductility, easy fracture, and limited energy dissipation in buckling-restrained braces during earthquakes, particularly in the core, and improves the toughness of the component by addressing energy dissipation issues. Specifically:

[0012] 1. Enhanced Seismic Performance: This application employs a double-yield-point structure, enabling phased energy dissipation. Through rational design, buckling-restrained braces are positioned at the weakest layer. Under dynamic loads such as earthquakes, the weakest layer reaches its yield point first, beginning energy dissipation under relatively small loads. This provides a buffer time for the structure to resist subsequent impacts, effectively reducing the initial impact of an earthquake on the overall structure. As the load continues to increase, the second-stage energy dissipation device activates, providing greater resistance to reduce inter-story deformation in the weakest layer. Simultaneously, the second yield point rapidly strengthens the structure's load-bearing capacity. Working in conjunction with the L-shaped core energy dissipation components and high-strength bolt groups on the outer side of the core, it precisely distributes axial pressure based on the real-time deformation state of the core, enhancing the stability and reliability of the structure under high loads and making the bracing more robust during disasters. Compared to traditional single-yield-point bracing, double-yield-point bracing enables adaptive control of the deformation mode under strong earthquakes, suppressing the weak-layer effect, significantly improving the ultimate deformation capacity and ultra-low cycle fatigue performance of the bracing, extending the structural service life, and reducing post-earthquake repair costs.

[0013] 2. Buckling-Free Characteristics: By designing a reasonable pore pattern and porosity, peanut-shaped pores are used to weaken the core component in the central weakening zone, preventing buckling instability under high loads. This "buckling-free" design, through reasonable adjustment of the component's geometry and constraints, ensures that the core does not undergo local or overall buckling deformation under stress, avoiding the performance degradation problems caused by buckling in traditional designs. Under extreme seismic conditions, the stability of the core component is guaranteed, effectively preventing buckling failure, thereby improving overall seismic performance and long-term service stability. Through buckling-free design, the structure can maintain good deformation capacity and efficient energy absorption, enhancing the seismic toughness of the components.

[0014] 3. Enhanced Ductility: The peanut-shaped perforation design induces a negative Poisson's ratio effect in the core components, causing them to exhibit a unique behavior of lateral contraction and longitudinal expansion under stress. This negative Poisson's ratio effect significantly suppresses lateral expansion of the core components during stress, inhibiting local buckling, while simultaneously improving the ductility of the components, enabling them to maintain load-bearing capacity even under large deformations. This design enhances the ductility of the components, giving the structure better deformation capacity, allowing it to absorb more energy through plastic deformation during strong earthquakes, thus enhancing the structure's seismic resistance and durability.

[0015] 4. Fracture-free characteristics: The inner and outer cores are firmly bound by the outer constraint, forming an effective outer constraint guarantee. When subjected to extreme seismic forces, the inner and outer core components may fracture due to large deformation. At this time, the outer constraint device, as the last line of defense, continues to bear the load, thereby achieving fracture-free characteristics.

[0016] 5. Highly efficient post-earthquake repair capability: Because the design fully considers the controllability of plastic deformation, the components can withstand repeated loads without serious damage or fracture after undergoing plastic deformation. Therefore, the support system's resilience is maintained after an earthquake; only the core components need to be replaced, without replacing the outer components. This design significantly reduces the difficulty and cost of post-earthquake repair.

[0017] It should be understood that the implementation of any embodiment of this application does not mean that it will simultaneously possess or achieve multiple or all of the above-mentioned beneficial effects. Attached Figure Description

[0018] To more clearly illustrate the embodiments of this application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0020] Figure 1 An isometric view of a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core is shown as an example.

[0021] Figure 2 An exemplary front view of a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core is shown.

[0022] Figure 3 An exemplary cross-sectional view of a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core is shown.

[0023] Figure 3A An exemplary diagram illustrates the plate gap of a high-ductility, fracture-free double-yield-point buckling restraint brace with a cruciform steel negative Poisson's ratio core.

[0024] Figure 4 An exploded view of a high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core is shown as an example.

[0025] Figure 5 An illustrative view of an isometric drawing of a first-order core of a cruciform steel negative Poisson's ratio core high-ductility fracture-free double-yield-point buckling-restrained brace is shown.

[0026] Figure 6 An exemplary view shows a front view of a first-order core of a cruciform steel negative Poisson's ratio core high-ductility fracture-free double yield point buckling restraint brace;

[0027] Figure 7 An isometric view of a second-order core of an angle steel cross-shaped steel negative Poisson's ratio core high ductility fracture-free double yield point buckling restraint brace is shown as an example.

[0028] Figure 8 An isometric view of an angle steel peripheral restraint brace with a cruciform steel negative Poisson's ratio core and high ductility, fracture-free double yield point buckling restraint is shown as an example.

[0029] Figure 9 An exemplary schematic diagram of a high-ductility, fracture-free double-yield-point buckling restraint brace with a cruciform steel negative Poisson's ratio core and an elongated hole is shown.

[0030] Marked in the image:

[0031] The first-order core of the cross-shaped steel is 1, the end connection area is 11, the round hole is 111, the negative Poisson's ratio weakening area in the middle is 12, and the peanut hole is 121.

[0032] Angle steel second-order core 2, end connection area 21, elongated hole 1 211, middle negative Poisson ratio weakening area 22, peanut hole 221;

[0033] Angle steel outer constraint 3, end connection area 31, oblong hole 2 311, middle pre-tightening area 32, round hole 2 321;

[0034] High-strength bolt group 4;

[0035] High-strength bolt group 25;

[0036] Pre-tightening pad 6.

[0037] In the various figures, the same or corresponding reference numerals indicate the same or corresponding parts. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and descriptions of this application are used to explain this application, but are not intended to limit this application.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] It should be understood that the terms "comprising / including," "consisting of," or any other variations are intended to cover non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements includes not only those elements but may also include, where necessary, other elements not expressly listed, or elements inherent to such a product, apparatus, process, or method. Without further limitation, an element defined by the phrases "comprising / including," "consisting of," does not exclude the presence of additional identical elements in the product, apparatus, process, or method that includes said element.

[0041] It should also be understood that the terms “upper,” “lower,” “front,” “back,” “left,” “right,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device, component, or structure referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation on this application.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0043] The following is a detailed description of the specific implementation and preferred scheme of the high ductility and fracture-free double yield point buckling restraint brace with a cross-shaped steel negative Poisson's ratio core proposed in this application for multi-story and high-rise prefabricated buildings.

[0044] Research on negative Poisson's ratio materials originated in the 1980s. Scientists discovered that certain special microstructures or material geometries can lead to the negative Poisson's ratio effect. From a microscopic perspective, the structural units of these materials undergo special rotation or twisting when subjected to stress, resulting in lateral deformation opposite to that of conventional materials. When a negative Poisson's ratio component is subjected to tensile or compressive forces, its internal periodic negative Poisson's ratio cells utilize their in-plane rotation mechanism to enable the component to exhibit excellent deformation performance, thereby dissipating more energy from the outside. Due to their outstanding energy absorption capacity, negative Poisson's ratio structures are widely used in many fields such as protection, vibration reduction, and energy absorption.

[0045] Double-yield-point bracing has two yielding stages, allowing it to gradually yield and dissipate energy under different stress levels. During minor and moderate earthquakes, double-yield-point bracing begins to dissipate energy at the lower yield point, and during major earthquakes, it continues to dissipate energy at the higher yield point, resulting in a smoother and more continuous energy dissipation process. Compared to single-yield-point bracing, double-yield-point bracing offers higher energy dissipation efficiency and better control over the phased energy dissipation of the structure, further enabling control over inter-story drift.

[0046] Based on the above understanding, this application studies a high-ductility, fracture-free, double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core, such as... Figure 1-4 As shown, it mainly includes: a first-order core of cross-shaped steel 1, a second-order core of angle steel 2, an outer constraint of angle steel 3, and a group of high-strength bolts. The first-order core of cross-shaped steel 1 includes a central negative Poisson's ratio weakening zone 12 formed within a predetermined length range in the middle of the steel, and end connection zones 11 on both sides; the second-order core of angle steel 2 includes a central negative Poisson's ratio weakening zone 22 formed within a predetermined length range in the middle of the steel, and end connection zones 21 at both ends; the outer constraint of angle steel 3 includes a central pre-tightening zone 32 formed within a predetermined length range in the middle of the angle steel, and end connection zones at both ends. Section 31; The first-stage core 1 of the cruciform steel, the second-stage core 2 of the angle steel, and the outer restraints 3 of the angle steel are arranged sequentially from the inside out. Four sets of second-stage core 2 of the angle steel are installed at the four corners of the first-stage core 1 of the cruciform steel, and four sets of outer restraints 3 are installed around the four sets of second-stage core 2 of the angle steel and pre-tightened in the central pre-tightening zone 32. The first-stage core 1 of the cruciform steel can slide longitudinally with a first displacement relative to the second-stage core 2 of the angle steel, and the second-stage core 2 of the angle steel can slide longitudinally with a second displacement relative to the outer restraints 3 of the angle steel, with the second displacement being greater than the first displacement. The resulting structure has two yield points, allowing the support to have two yield stages when the structure undergoes large deformation, thus improving the overall ductility of the structure and preventing component fracture.

[0047] For details, see Figure 4-6The illustration exemplifies a structure of a first-order core made of cruciform steel. The first-order core 1 is made of cruciform steel and serves as the internal core of the entire component. The two ends of the first-order core 1 are used to connect to the main building structures on both sides. Bolt holes can be provided as needed, or it can be welded to the building structures on both sides.

[0048] The cross-shaped steel is designed with two sections facing inwards and upwards along its axis. The inner side is the end connection area 11. The end connection area 11 has a circular hole 111. The circular hole 111 is used to connect and fix the angle steel second-stage core 2 and the outer constraint 3 of the angle steel through a group of high-strength bolts 4. Since it is a circular hole, the axial force is transmitted through the group of high-strength bolts 4 to achieve the purpose of structural collaborative operation.

[0049] It should be noted that, as Figure 3A As shown, the first-stage core 1 of the cross-shaped steel and the second-stage core 2 of the outer angle steel are not tightly attached; a certain gap needs to be left between the plates to allow the first-stage core 1 of the cross-shaped steel to have some deformation space. Similarly, the second-stage core 2 of the angle steel and the outer constraint 3 of the angle steel are not tightly attached; a certain gap needs to be left between the plates to allow the second-stage core 2 of the angle steel to have some deformation space. The required gap can be achieved by setting different positions for the bolt holes of the upper and lower limbs and the left and right limbs of the first-stage core 1 of the cross-shaped steel, as if the second-stage core is hung on the first-stage core. For example, if it is necessary to maintain the gap between the horizontal planes, the second-stage core is hung higher; if it is necessary to maintain the gap between the vertical planes, the second-stage core is hung further away. If the dimensions of the horizontal plane and the vertical plane of the component are inconsistent, bolt holes at different distances should be set if the same gap is to be maintained. If the dimensions are consistent, bolt holes at the same distance can also be set. In short, the goal is to maintain the gap between the first-stage core 1 of the cross-shaped steel and the second-stage core 2 of the outer angle steel of the core.

[0050] Inside the end connection area 11, a negative Poisson's ratio weakening zone 12 is designed within a predetermined length range in the middle of the steel section. The specific weakening length and degree are determined according to design requirements. This central weakening zone, as the core part of the core component, is specifically designed as a weakening area to control the plastic deformation region of the component. By weakening the central region, its load-bearing capacity is made lower than that of other external regions. This design effectively guides plastic deformation to occur in the middle of the member, preventing excessive plastic deformation or damage in other areas, thereby improving the system's energy dissipation capacity.

[0051] Specifically, peanut-shaped through-holes (121) are created in the central negative Poisson's ratio weakening zone 12. These "peanut-shaped through-holes" are easily understood. The peanut-shaped through-holes (121) are arranged alternately horizontally and vertically in the central negative Poisson's ratio weakening zone 12, specifically in a multi-row, multi-column matrix arrangement along the four limbs of the cross-shaped steel section. Figure 6As shown, in the same row, a horizontal peanut-shaped hole alternates with a vertical peanut-shaped hole, and in the same column, a vertical peanut-shaped hole alternates with a horizontal peanut-shaped hole. The weakening zone of the first-order core of the cruciform steel is designed as a peanut-shaped hole structure, giving the structure a negative Poisson's ratio characteristic. A negative Poisson's ratio structure has better plasticity and toughness, thus providing better structural protection. Furthermore, when undergoing large deformations, especially plastic deformation, the negative Poisson's ratio structure generates higher energy dissipation, improving the energy dissipation capacity of the supporting structure and effectively reducing the damage to the structure from impact forces. A well-designed thickness and porosity can prevent buckling of the structure. Although the load-bearing capacity is weakened, it can more efficiently utilize the energy dissipation capacity under small to medium earthquakes.

[0052] The opening ratio of peanut-shaped holes is determined according to design requirements. If the opening ratio is too small, the negative Poisson's ratio effect will be difficult to reflect. If the opening ratio is too large, the structural strength will be difficult to guarantee. Studies have shown that an opening ratio of 40-50% is appropriate, that is, a solid ratio of 50-60% is a reasonable range.

[0053] See also Figure 4 , 7 The diagram illustrates the structure of a second-order core of angle steel. The second-order core 2 is made of angle steel or L-shaped steel and is attached to the periphery of the first-order core 1 of cross-shaped steel. The second-order core 2 is divided into two areas: the end connection area 21 and the middle negative Poisson's ratio weakening area 22. The end connection area 21 is located at both ends of the second-order core 2. The end connection area 21 has elongated holes 211. The diagram shows that there are three elongated holes 211 on each of the two limbs of the second-order core 2. They are connected and fixed to the end connection area 111 of the first-order core 1 of cross-shaped steel by means of a group of high-strength bolts 4. The semi-circular dimension of the elongated hole 211 is consistent with the dimension of the circular hole 111 on the end connection area 11 of the first-stage core 1 of the cross-shaped steel. They are connected by a group of high-strength bolts 4. The connection between the circular hole and the elongated hole enables the first-stage core and the second-stage core to work together to achieve the effect of double yield point support. When the first-stage core 1 of the cross-shaped steel deforms, the high-strength bolt can slide from one end to the other in the elongated hole, thereby transmitting force through the high-strength bolt.

[0054] The central negative Poisson's ratio weakening zone 22 is also located within a predetermined length range in the middle of the second-order core of the angle steel. The specific weakening length and degree are determined according to design requirements. As the core part of the second-order core component, the central weakening zone is specifically designed as a weakening area to control the plastic deformation region of the component. By weakening the central region, its load-bearing capacity is made lower than that of other external regions. This design effectively guides plastic deformation to occur in the middle of the member, preventing excessive plastic deformation or damage in other areas, thereby improving the system's energy dissipation capacity.

[0055] Similarly, peanut-shaped holes 221 are opened in the central negative Poisson's ratio weakening zone 22. These peanut-shaped holes 221 are arranged alternately horizontally and vertically in the central negative Poisson's ratio weakening zone 22. Specifically, they are arranged in a multi-row, multi-column matrix pattern on both sides of the second-order core 2 of the angle steel, such as... Figure 7 As shown, in the same row, a horizontal peanut-shaped hole alternates with a vertical peanut-shaped hole, and in the same column, a vertical peanut-shaped hole alternates with a horizontal peanut-shaped hole. The opening ratio of the peanut-shaped holes is determined according to the design requirements. Similar to the first-order core 1 of the cross-shaped steel, the structure has a negative Poisson's ratio characteristic by creating holes in the second-order core 2 of the angle steel to achieve the same purpose.

[0056] In addition, since the second-order core 2 of the angle steel also has a perforated form, it may reduce the load-bearing capacity of the entire component too much. In order to improve the load-bearing capacity of the component and resist higher intensity earthquakes, a dog bone weakening plate with a smaller weakening rate can also be used to improve the second-order load-bearing capacity and thus improve the load-bearing capacity of the entire component.

[0057] It should be noted that the opening form must first enable the first-order and second-order cores to exhibit a negative Poisson's ratio effect. Since the second-order core 2 of the angle steel and the first-order core 1 of the cross-shaped steel have different structural forms, the opening forms of peanut hole 221 and peanut hole 121 can be the same or different, as long as the negative Poisson's ratio effect can be achieved within a reasonable opening range.

[0058] See also Figure 4 , 8 The diagram illustrates a structural diagram of an angle steel perimeter constraint. The angle steel perimeter constraint 3 is made of angle steel or L-shaped steel and is attached to the periphery of the second-order core 2 of the angle steel. It forms end connection areas 31 at both ends and a central pre-tightening area 32 in the middle. The end connection areas 31 have elongated holes 311 with the same number, size and position as the elongated holes 211 of the second-order core 2 of the angle steel. The elongated holes 211, elongated holes 311 and round holes 111 are connected and fixed by a group of high-strength bolts 4, thereby fixing the angle steel perimeter constraint 3 to the periphery of the second-order core 2 of the angle steel and fixing them together to the four corners of the first-order core 1 of the cross-shaped steel.

[0059] It should be noted that the high-strength bolt group 4 is connected but not tightened; that is, no preload is applied, only connection is required. When the component is under stress, for example, when the earthquake intensity is low, the first-order core 1 of the cross-shaped steel deforms first, which is the first-order energy dissipation. When the earthquake intensity is high, as the deformation gradually intensifies, the high-strength bolt in the circular hole 111 gradually contacts and is stuck to the hole wall of the oblong hole 211. At this time, the second-order core 2 of the angle steel begins to bear part of the load, providing additional support force, which is the second-order energy dissipation, thus achieving the effect of double yield points.

[0060] Preferably, the elongated hole 311 is designed to be longer than the elongated hole 211, such as... Figure 9As shown in the figure, orange represents oblong hole 2 (311) and red represents oblong hole 1 (211). This allows sufficient energy to be dissipated internally before the external structure can begin to function, leaving room for the internal structure to play its role.

[0061] In addition, the outer constraint 3 of the angle steel also has two round holes 321 on the sides of the two limbs of the pre-tightening zone 32 in the middle. The number of round holes 321 on the two limbs of the pre-tightening zone 32 in the middle is determined according to the design requirements. The figure shows that they are densely opened at both ends, and the distance between them in the middle area can be appropriately increased. The round holes 321 are used to connect and fix the two adjacent groups of outer constraints 3 of angle steel through the high-strength bolt group 5 and to pre-tighten them.

[0062] Based on the above explanation, combined with Figure 1 , 3 During assembly, the first-stage core 1 of the cross-shaped steel is located at the innermost core position of the entire support. The four sets of second-stage cores 2 of angle steel are respectively attached to the four corners of the first-stage core 1 of the cross-shaped steel. The four sets of outer constraints 3 of angle steel are respectively attached to the outer periphery of the four sets of second-stage cores 2 of angle steel. They are connected and fixed but not pre-tightened by high-strength bolt group 4 passing through oblong hole 311, oblong hole 211 and round hole 111. The two adjacent sets of outer constraints 3 of angle steel are connected, fixed and pre-tightened by high-strength bolt group 25 passing through round hole 321 on the side of the outer constraint 3 of the adjacent angle steel.

[0063] In this embodiment, the purpose of fastening the high-strength bolt group 2 5 in the circular hole 2 321 is to firmly bind the four sets of angle steel peripheral constraints 3 to the four corners of the inner and outer double cores through the high-strength bolt group 2 5, thereby providing effective peripheral constraint protection for the first-order core and second-order core energy dissipation components. When subjected to extreme seismic action, the cross-shaped steel first-order core component and the angle steel second-order core component may fracture due to large deformation. At this time, the channel steel peripheral constraint device, as the last line of defense, continues to bear the load, thereby achieving the fracture-free characteristic.

[0064] Thus, by creating perforations in the first-order core component of the cruciform steel, the structure acquires negative Poisson's ratio characteristics. When the first-order core is subjected to axial force, the negative Poisson's ratio allows the structure to absorb external force energy through special deformation behaviors (bending, torsion, or other nonlinear deformations), converting the absorbed mechanical energy into elastic or plastic energy. Furthermore, negative Poisson's ratio structures exhibit high toughness and plasticity, meaning they can undergo significant deformation under external forces without easily fracturing. This deformation adaptability allows the material to function effectively over a wider deformation range. Compared to traditional positive Poisson's ratio structures, this plastic deformation absorbs a large amount of energy, effectively protecting the structure from severe impacts or overloads. Moreover, a well-designed thickness and perforation method can effectively prevent out-of-plane deformation of the core, reducing the thickness requirements of the outer components.

[0065] When the first-stage core 1 of the cross-shaped steel deforms, the high-strength bolt group 4 moves within the elongated hole 211 of the second-stage core 2 of the angle steel along with the circular hole 111 at the end of the first-stage core 1 of the cross-shaped steel. When the high-strength bolt moves to one end of the elongated hole, the first-stage core 1 of the cross-shaped steel has undergone a certain degree of deformation. The second-stage core 2 of the angle steel outside the core begins to be subjected to the force transmitted by the high-strength bolt and begins to share the force of the first-stage core 1 of the cross-shaped steel, thereby achieving the effect of double yield point.

[0066] The outer constraint 3 of the angle steel forms a protective sleeve on the outside of the entire support. When the first-stage core 1 of the cross-shaped steel and the second-stage core 2 of the angle steel undergo large deformation, the protective sleeve can play a buckling restraint role, thereby preventing the support from breaking. When the core fails, the axial force will be transmitted to the outer constraint 3 of the angle steel through the high-strength bolt group 2 5. Since the outer constraint 3 of the angle steel has a larger cross-sectional area than the first-stage core 1 of the cross-shaped steel and the second-stage core 2 of the angle steel, it can bear greater internal forces.

[0067] See also Figure 1-4 In one embodiment of this application, the buckling restraint support further includes a pre-tightening pad 6. Since the second-order core 2 of the angle steel and the outer restraint 3 of the angle steel are both located at the four corners of the first-order core 1 of the cross-shaped steel, that is, two adjacent second-order cores 2 of the angle steel and the outer restraint 3 of the angle steel clamp one limb of the first-order core 1 of the cross-shaped steel. Figure 3 As shown, a pre-tightening pad 6 is set between one leg of the first-stage core 1 of the cross-shaped steel and the outer perimeter constraint 3 of the two adjacent angle steels. The thickness of the pre-tightening pad 6 is the sum of the thickness of one leg of the first-stage core 1 of the cross-shaped steel and the thickness of the two legs of the second-stage core 2 of the angle steel. That is, the thickness of the pre-tightening pad 6 is consistent with the distance between the two legs of the outer perimeter constraint 3 of the two adjacent angle steels. This allows the pre-tightening pad 6 to fill the gap after the outer perimeter constraint 3 of the angle steel is fixed. The gap between the outer perimeter constraint 3 of the angle steel and the internal components is controlled by the thickness of the pad.

[0068] Furthermore, a circular hole 61 is provided on the pre-tightening pad 6, and a group of high-strength bolts 5 are connected and fixed to the circular hole 61 on the pre-tightening pad 6 by passing through the circular hole 321 on the outer restraint 3 side of the adjacent angle steel. Multiple circular holes 61 are evenly distributed along the longitudinal direction of the pre-tightening pad 6, and the number of circular holes 61 can be appropriately increased near both ends of the pre-tightening pad 6.

[0069] Optionally, the pre-tightening pad 6 can be a perforated, continuous strip plate with the same length as the second-stage core 2 and the outer constraint 3 of the angle steel, or multiple perforated pads. The figure shows four perforated, continuous single plates, which makes assembly easier.

[0070] In one embodiment of this application, the length L1 of the first-order core 1 of the cross-shaped steel, the length L2 of the second-order core 2 of the angle steel, and the length L3 of the outer constraint 3 of the angle steel satisfy the relationship L1>L2=L3, that is, the second-order core 2 of the angle steel and the outer constraint 3 of the angle steel are of equal length and their two ends are aligned, but are less than the length of the first-order core 1 of the cross-shaped steel. Thus, the two ends of the first-order core 1 of the cross-shaped steel extend beyond the two, and the extended part is used to connect the main structure of the building.

[0071] In one embodiment of this application, the widths W1 of each limb of the first-order core 1 of the cross-shaped steel, the widths W2 of each limb of the second-order core 2 of the angle steel, and the widths W3 of each limb of the outer constraint 3 of the angle steel satisfy the relationship W1=W2<W3, that is, the widths of each limb of the first-order core 1 of the cross-shaped steel are the same as the widths of each limb of the second-order core 2 of the angle steel. Thus, after the second-order core 2 of the angle steel is attached to the four corners of the first-order core 1 of the cross-shaped steel, the boundaries of each limb remain flush, making the entire component have a flat appearance.

[0072] Furthermore, after the outer perimeter constraint 3 of the angle steel is attached to the outside of the second-order core 2 of the angle steel, the boundaries of each limb of the outer perimeter constraint 3 of the angle steel exceed the boundaries of each limb of the second-order core 2 of the angle steel, which facilitates the opening of round holes 321 on the limb edges of each limb of the outer perimeter constraint 3 of the angle steel and the insertion of high-strength bolt groups 5.

[0073] Based on this, the length of the pre-tightening pad 6 is consistent with the length L2 of the second-order core 2 of the angle steel and the length L3 of the outer constraint 3 of the angle steel, and the width is the difference between the width W3 of each limb of the outer constraint 3 of the angle steel and the width W1 of each limb of the first-order core 1 of the cross-shaped steel (or the width W2 of each limb of the second-order core 2 of the angle steel) (ignoring the influence of the thickness of each limb).

[0074] In one embodiment of this application, the two ends of the first-stage core 1 of the cross-shaped steel are plated, for example by welding or structural adhesive bonding, to enhance rigidity and prevent buckling failure at the outer end of the first-stage core 1 of the cross-shaped steel, ensuring that the failure occurs later than the core component.

[0075] In one embodiment of this application, the first-order core 1 of the cross-shaped steel and the second-order core 2 of the angle steel are made of high-ductility materials. High-ductility materials include low-yield-point steel, aluminum alloys, or iron-based shape memory alloys, etc.

[0076] In one embodiment of this application, PTFE tape is adhered to the mating surfaces of the first-order core 1 of the cross-shaped steel, the second-order core 2 of the angle steel, and the outer constraint 3 of the angle steel to reduce the influence of friction on the symmetry of the tensile and compressive bearing capacity of the support.

[0077] As described above, the high-ductility, fracture-free double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core provided in this application mainly consists of a first-order cruciform steel core member with peanut-shaped holes, four second-order angle steel cores with peanut-shaped holes, four external constraints of angle steel, and a group of high-strength bolts. This buckling-restrained brace can improve the overall ductility of the component and prevent it from fracturing. When the core has large deformation, the axial force can be transferred through the second-order angle steel cores and the group of high-strength bolts on the outer side of the core. By creating peanut-shaped holes in the first-order cruciform steel core and the second-order angle steel core, the structure has a negative Poisson's ratio characteristic. The external constraint device serves to prevent buckling instability of the first-order cruciform steel core member and the second-order angle steel cores on the outer side of the core. When the first-order cruciform steel core is subjected to axial force, due to the characteristics of negative Poisson's ratio, the structure is allowed to absorb external force energy through special deformation behavior (bending, torsion, or other nonlinear deformation), converting the externally absorbed mechanical energy into elastic or plastic energy. Furthermore, the negative Poisson's ratio structure has high toughness and plasticity, which means that under the action of external force, they can undergo large deformation without easily undergoing brittle fracture. This plastic deformation absorbs a large amount of energy, thus effectively protecting the structure from severe impacts or overloads.

[0078] When the first-order core of the cruciform steel enters the plastic stage, the first stage of the structure begins to yield. As the axial force increases, the outer side of the core begins to share the axial force on the first-order core of the cruciform steel with the help of the movement of the high-strength bolt group in the elongated hole, and gradually enters the plastic state. Thus, the support has two yield stages, achieving higher energy dissipation efficiency.

[0079] When both the first-order core of the cruciform steel and the core energy-dissipating component of the angle steel undergo significant deformation, the outer constraint device forms a protective sleeve from the outside, which plays a role in buckling constraint, thereby preventing the support from breaking. It can effectively achieve buckling constraint of the first-order core of the cruciform steel and the second-order core of the angle steel core energy-dissipating component outside the core. Furthermore, when the core fails, the axial force will be transferred to the outer constraint of the angle steel through the high-strength bolt group, and the outer constraint of the angle steel will continue to bear greater internal forces.

[0080] While several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this application. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

Claims

1. A high-ductility, fracture-free, double-yield-point buckling-restrained brace with a cruciform steel negative Poisson's ratio core, characterized in that... include: The first-order core of the cross-shaped steel includes a central negative Poisson's ratio weakening zone formed within a predetermined length range in the middle of the steel, and end connection zones on both sides. The second-order core of the angle steel includes a central negative Poisson's ratio weakening zone II formed within a predetermined length range in the middle of the steel section, and an end connection zone II at both ends; The outer restraint of the angle steel includes a central pre-tightening zone formed within a predetermined length range in the middle of the angle steel, and end connection zones at both ends. The four sets of second-order cores of the angle steel are respectively installed at the four corners of the first-order core of the cross-shaped steel. The four sets of external constraints of the angle steel are respectively installed on the periphery of the four sets of second-order cores of the angle steel and pre-tightened in the central pre-tightening zone. The first-order core of the cross-shaped steel can produce a first displacement longitudinal sliding relative to the second-order core of the angle steel, and the second-order core of the angle steel can produce a second displacement longitudinal sliding relative to the external constraints of the angle steel. The second displacement is greater than the first displacement.

2. The buckling-restrained brace according to claim 1, characterized in that, The central negative Poisson's ratio weakening region is provided with peanut-shaped holes, which enable the first-order core of the cross-shaped steel to form a negative Poisson's ratio effect; the peanut-shaped holes are arranged in an alternating horizontal and vertical array in the central negative Poisson's ratio weakening region. The second negative Poisson's ratio weakening region in the middle is formed by opening two peanut-shaped holes, which causes the second-order kernel of the angle steel to form a negative Poisson's ratio effect; the second peanut-shaped holes are arranged in an alternating horizontal and vertical array in the second negative Poisson's ratio weakening region in the middle.

3. The buckling-restrained brace according to claim 1, characterized in that, A circular hole is provided in the end connection area; The end connection area 2 is provided with an elongated hole 1, which corresponds to the circular hole 1; The end connection area three has an elongated hole two that is longer than the elongated hole one, and the elongated hole two corresponds to the elongated hole one and the hole one; The four sets of second-order cores of the angle steel are respectively set at the four corners of the first-order core of the cross-shaped steel. The four sets of external constraints of the angle steel are respectively set on the periphery of the four sets of second-order cores of the angle steel, and are connected and fixed by a group of high-strength bolts passing through the second elongated hole, the first elongated hole, and the first round hole.

4. The buckling-restrained brace according to claim 1, characterized in that, The central pre-tightening zone has two round holes on the sides of each leg of the angle steel. High-strength bolts are used to pass through the round holes on the periphery of two adjacent groups of angle steel to connect, fix and pre-tighten the legs.

5. The buckling-restrained brace according to claim 4, characterized in that, The buckling restraint support also includes: A pre-tightening pad is provided in the middle pre-tightening area between the two outer restraints of two adjacent groups of angle steels, and a third round hole is provided on the pre-tightening pad. A group of high-strength bolts passes through the second round hole of the two outer restraints of the two adjacent groups of angle steels and is connected and fixed to the third round hole on the pre-tightening pad for pre-tightening.

6. The buckling-restrained brace according to claim 5, characterized in that, The pre-tightening pad is a perforated, elongated strip plate with the same length as the second-order core of the angle steel and the outer constraint of the angle steel, or it may be multiple perforated pads.

7. The buckling-restrained brace according to claim 1, characterized in that, The length L1 of the first-order core of the cross-shaped steel, the length L2 of the second-order core of the angle steel, and the length L3 of the outer constraint of the angle steel satisfy L1 > L2 = L3. The portions of the first-order core of the cross-shaped steel that extend beyond both ends are used to connect to the main structure of the building.

8. The buckling-restrained brace according to claim 1, characterized in that, The first-stage core of the cruciform steel and the second-stage core of the angle steel are made of high-ductility materials, including low-yield-point steel, aluminum alloy or iron-based shape memory alloy.

9. The buckling-restrained brace according to claim 1, characterized in that, PTFE tape is applied to the mating surfaces of the first-stage core of the cross-shaped steel, the second-stage core of the angle steel, and the outer constraint of the angle steel to reduce the influence of friction on the symmetry of the tensile and compressive bearing capacity of the support.

10. A multi-story, high-rise prefabricated building, comprising the buckling-restrained brace as described in any one of claims 1 to 9.

Images