Assembled x-shaped buckling-restrained brace with built-in parallel-stripped steel plates in staggered and superimposed middle part

Abstract

The application relates to an assembled X-shaped buckling-restrained brace with built-in parallel strip steel plates in the middle staggered superposition of a rotatable steel member, and relates to the field of building structure earthquake resistance. The application solves the problems of the existing X-shaped buckling-restrained brace, such as difficult maintenance and replacement, middle connection defects, discontinuous constraint, sudden load capacity reduction and insufficient local bending resistance. The application comprises a built-in steel plate support and a constraint steel member. The built-in steel plate support is arranged in two directions and is not connected in the middle. The constraint steel member is arranged outside the built-in support and is provided with a rotatable connection in the middle staggered superposition area. The built-in steel plate support is a slotted steel plate support or a strip steel plate support. A gap is left between the built-in steel plate support and the constraint steel member in the axial direction, the plate thickness direction and the plate width direction. The built-in steel plate support and the constraint steel member are rotatably connected through bolts without pre-tightening force in the middle staggered superposition area. The application is used in building construction.

Description

Technical Field

[0001] This invention relates to the field of seismic resistance of building structures, specifically to an X-shaped buckling-resistance brace with internally arranged parallel steel plates built into a centrally interlocking rotatable steel component, for use in the construction industry. Background Technology

[0002] 1) In the existing commonly used buckling-restrained brace structures, when the restraint members are integrally welded steel components or integrally cast reinforced concrete with mortar filling in steel pipes, the integrally manufactured restraint members are not conducive to the inspection and replacement of the internal braces. After the internal brace fails due to low-cycle fatigue, even if the restraint members are intact, they are difficult to reuse. Moreover, these structures are difficult to form an X-shaped buckling-restrained brace arrangement with internal braces arranged along the entire length, which deteriorates the ductility and energy dissipation capacity of the brace.

[0003] Because traditional integrated restraint components cannot be reused, the entire brace must be replaced after it breaks. Therefore, existing buckling-restrained braces present difficulties in maintenance and replacement.

[0004] 2) In existing X-shaped buckling-restrained braces, when the two built-in braces in two directions are fixedly connected at the middle, defects and stress concentrations inevitably exist at the middle connection, which will degrade the ductility and energy dissipation capacity of the brace. After the middle connection, the stress and deformation of the braces in the two directions directly affect each other, making it difficult to accurately predict the hysteretic stress behavior of the buckling-restrained brace in each direction. Furthermore, when half of the brace in one direction breaks, the unbroken half of the brace in that direction will affect the stress and deformation of the unbroken brace in the other direction through the middle connection, thus degrading the hysteretic performance of the entire X-shaped buckling-restrained brace after fracture.

[0005] The fixed connection at the middle of the two-way support leads to stress concentration, which degrades ductility and energy dissipation capacity. Therefore, defects in the middle connection can easily cause stress concentration.

[0006] 3) In the existing buckling-restrained brace construction, in order to leave appropriate axial clearance between the two ends of the restraint member and the built-in brace, it is often necessary to weld a limiting clip in the middle of the built-in brace or to limit the restraint member by locally changing the cross section of the built-in brace in the middle of the brace. This makes the cross section in the middle of the built-in brace prone to processing defects, and the local abrupt change in the middle section will also lead to stress concentration, which makes the cross section in the middle of the built-in brace prone to premature tensile cracking and fracture, thus deteriorating the hysteresis performance of the brace.

[0007] 4) In the existing X-shaped buckling-restrained brace structure, in the rotational structure of the restraint member at the intersection of two braces, the restraint member in one direction is always completely disconnected on the front or back of the brace, which cannot reliably provide continuous lateral restraint for the built-in brace. This often leads to the restraint member failing in the middle due to insufficient local bending resistance, thus deteriorating the ductility of the brace.

[0008] Because the existing structure has the constraint members broken at the front or back, it causes problems of insufficient lateral constraint capacity and discontinuous constraint capacity.

[0009] 5) In the existing X-shaped buckling-restrained brace construction, when the built-in brace sections used in both directions are large under the requirement of high bearing capacity, if the steel plate brace in one direction breaks, the total lateral force resistance capacity of the brace will be halved, which will lead to a sudden drop in the lateral stiffness and bearing capacity of the entire X-shaped brace, which will be detrimental to the gradual transition and redistribution of internal forces in the structure and affect the structural safety.

[0010] Because the existing structure uses a single, continuous steel plate, the X-shaped support experiences a sharp drop in load-bearing capacity after the steel plate breaks.

[0011] 6) In the existing X-shaped buckling-restrained brace construction, when the built-in brace sections used in both directions are relatively wide, in order to enable the restraint members to rotate relative to each other at the intersection of the two braces, the rotating structure of the central restraint member with a disc of the same size often leads to an excessively large spacing of high-strength bolts in the central assembly area. In other words, the bolt spacing of the rotating structure in the central part of the wide cross-section brace is too large, which easily leads to local bending failure of the restraint members, thereby deteriorating the ductility, bearing capacity and energy dissipation capacity of the brace.

[0012] The excessively large spacing between the connecting bolts of the restraining member due to the central rotational connection deteriorates the local bending resistance of the restraining member in the central rotational region. Therefore, the restraining member is prone to localized bending failure.

[0013] In summary, existing X-shaped buckling-restrained braces suffer from problems such as difficulties in maintenance and replacement, defects in the central connection, discontinuous restraint, sudden drop in bearing capacity, and insufficient local bending resistance. Summary of the Invention

[0014] The purpose of this invention is to solve the problems of existing X-shaped buckling-restrained braces, such as difficulties in maintenance and replacement, defects in the central connection, discontinuous restraint, sudden drop in bearing capacity, and insufficient local bending resistance. In order to provide an assembled X-shaped buckling-restrained brace with a centrally interlocked and rotatable steel component and built-in parallel strip steel plates.

[0015] The technical solution of this invention is:

[0016] An X-shaped buckling-resistance brace consisting of internally arranged parallel strip steel plates and a centrally staggered, rotatable steel component includes an internal steel plate support and a restraining steel component. The internal steel plate support is staggered in two directions and not connected in the middle. The restraining steel component is laid outside the internal support and has a rotatable connection in the central staggered area. The internal steel plate support is a slotted steel plate support or a strip steel plate support. A gap is left between the internal steel plate support and the restraining steel component along the axial direction and in the plate thickness and width directions.

[0017] Furthermore, the central overlapping area of ​​the built-in steel plate support and the constrained steel components is rotatably connected by bolts without preload.

[0018] Furthermore, when the built-in steel plate support is a slotted steel plate support, the built-in steel plate support includes a slotted first support plate, a slotted second support plate, and slotted stiffening ribs. The slotted first support plate and the slotted second support plate are both provided with long slots in the middle of their length direction, and the slotted first support plate and the slotted second support plate are arranged alternately. Slotted stiffening ribs are welded to both ends of the slotted first support plate and the slotted second support plate.

[0019] Furthermore, when the built-in steel plate support is a slotted steel plate support, the constraint steel components include slotted constraint strips in one direction, slotted constraint strips in two directions, a thin steel plate in one direction, a thin steel plate in two directions, a slotted back constraint skeleton, and a slotted front constraint skeleton. The thin steel plate in one direction is installed on the slotted constraint strips to form slotted constraint one, and the thin steel plate in two directions is installed on the slotted constraint strips to form slotted constraint two. Slotted constraint one and slotted constraint two are respectively installed on the slotted first support plate and the slotted second support plate. The slotted back constraint skeleton and the slotted front constraint skeleton are installed on slotted constraint one and slotted constraint two from the back and the front, respectively.

[0020] Furthermore, the slotted constraint unidirectional constraint strip includes two outer continuous perforated strips, an inner middle perforated strip, and two inner end perforated strips; the two outer continuous perforated strips are arranged in parallel, the inner middle perforated strip is located between the two outer continuous perforated strips, and the two inner end perforated strips are located on both sides of the inner middle perforated strip.

[0021] Preferably, two elongated holes are provided on the perforated strip at the inner end of the support, one of which partially overlaps with one end of the perforated strip at the middle of the inner side of the support.

[0022] Preferably, the slotted constraint thin steel plate includes four thin steel plates with open holes on the outer side of the support, two thin steel plates with open holes on the middle of the inner side of the support, and two slotted strips on the end of the inner side of the support; the two thin steel plates with open holes on the outer side of the support are arranged in a group along the length direction, and the two groups of thin steel plates with open holes on the outer side of the support are arranged in parallel, the two thin steel plates with open holes on the middle of the inner side of the support are located between the two groups of thin steel plates with open holes on the outer side of the support, and the two slotted strips on the end of the inner side of the support are located on both sides of one of the thin steel plates with open holes on the middle of the inner side of the support.

[0023] Furthermore, the back-side constraint skeleton and the front-side constraint skeleton of the slot are structurally identical. The back-side constraint skeleton of the slot includes a first perforated constraint steel plate, two first perforated pads, a second perforated constraint steel plate, and two second perforated pads. The two first perforated pads are installed on the inner side of the first perforated constraint steel plate to form the first back-side skeleton, and the two second perforated pads are installed on the inner side of the second perforated constraint steel plate to form the second back-side skeleton. The first back-side skeleton and the second back-side skeleton are arranged alternately and installed on the slotted constraint one-direction constraint strip and the slotted constraint two-direction constraint strip. The opposite ends of the two first perforated pads and the two second perforated pads are zigzag-shaped.

[0024] Furthermore, when the built-in steel plate support is a slab steel plate support, the built-in steel plate support includes a first group of slab support plates, a second group of slab support plates, and slab stiffening ribs, with two slab stiffening ribs installed at each end of the first group of slab support plates and the second group of slab support plates.

[0025] Furthermore, when the built-in steel plate support is a slab steel plate support, the restraining steel components include slab support one-direction restraining strips, slab support two-direction restraining strips, slab support one-direction thin steel plates, slab support two-direction thin steel plates, slab back restraining skeletons, and slab front restraining skeletons. The slab support one-direction restraining strips are installed on the first group of slab support plates. The slab support one-direction thin steel plates are discontinuous thin steel plates and are installed on the slab support one-direction restraining strips. The slab support two-direction restraining strips and slab support two-direction thin steel plates are respectively installed on the left and right sides of the second group of slab support plates. The slab back restraining skeletons and slab front restraining skeletons are respectively installed on the slab support one-direction thin steel plates and slab support two-direction restraining strips.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. This invention employs a fully prefabricated steel component structure, improving the punching shear resistance of the restraint members and preventing brittle failure. Within the structural plane, the restraint members in both directions and the central portion of the internal supports are arranged in an alternating manner and can rotate relative to each other, making the X-shaped buckling-restrained brace arrangement easier to implement and better utilizing the ductility of the buckling-restrained braces. Simultaneously, the prefabricated structure facilitates the inspection and replacement of the internal supports and the reuse of well-maintained restraint members.

[0028] 2. This invention separates and staggers the built-in supports in two directions, preventing them from connecting at the midpoint. This avoids stress concentration caused by abrupt changes in the cross-section and premature breakage due to connection defects. Axial stress and deformation are more uniform along the entire support length, better utilizing the support's plastic deformation and energy dissipation capabilities. Furthermore, it prevents the stress on one support from interfering with the stress on the other, facilitating deformation coordination between the two built-in supports and avoiding adverse effects. It also allows for accurate prediction of the buckling-resistance brace's hysteretic behavior in each direction. Simultaneously, even if one built-in support breaks, it will not interfere with the normal stress distribution of the other support, thus improving the overall support's post-breakage stress performance.

[0029] 3. When the internal steel plate supports of the X-shaped buckling-restrained brace of the present invention are arranged in an alternating manner in two directions, after the constraint members in the two directions are also staggered and assembled together in the entire X-shaped brace plane, the constraint member laid on the built-in support in one direction will slide along the axial direction of the support and will be constrained in the middle region by the built-in steel plate supports arranged in an alternating manner in the other direction. In this way, the built-in supports in the two directions can provide a natural limiting function for the external constraint members, avoiding the local weakening of the cross section or the introduction of defects caused by additional openings for limiting or additional welding of limiting steel components on the built-in supports. This can ensure better uniform stress distribution and development of plastic deformation in the built-in supports in both directions, and improve the ductility and energy dissipation capacity of the X-shaped buckling-restrained brace.

[0030] 4. In this invention, the built-in staggered and continuous two-directional steel plate support arrangement addresses the issue of prefabricated X-shaped constraint members. When the constraint member skeleton is made of constraint steel plates with welded steel pipes, the staggered steel pipes occupy too much space in the thickness direction, necessitating the disconnection of one steel pipe on the front or back of one support direction. When a steel pipe is disconnected in one direction of the constraint member on one side of the front or back, the constraint steel plate in that direction remains continuous, while the steel pipe in the other direction remains continuous while the constraint steel plate is disconnected. This disconnection significantly degrades the local bending resistance of the central constraint member. When the constraint member skeleton is directly made of constraint steel plates, the constraint members in both directions can remain continuous without disconnection. This facilitates the staggered arrangement of the constraint members in both directions to achieve mutual rotation while maintaining the continuity of the constraint members, thereby ensuring that the constraint members on the front or back can provide continuous lateral constraint for the built-in support and improving the local bending resistance of the constraint member skeleton.

[0031] 5. In the application of the X-shaped buckling-restrained brace of the present invention, when a large axial force is required to meet the bearing capacity requirements, the fracture of the built-in brace in one direction will abruptly and significantly weaken the lateral resistance of the brace, which is detrimental to the structural stress. After separating the built-in brace in one direction into two built-in steel plate braces, the possibility of the built-in brace under stress in one direction simultaneously fracturing under tension is greatly reduced. In particular, when two built-in braces with different yield strengths and plastic deformation capabilities are arranged side by side in the same direction, it is easier to control the successive fracture of the brace section. In this way, even if the brace fractures under tension, the smaller cross-section of the successively fractured brace results in a smaller amplitude of the successive reduction in bearing capacity, which helps the lateral bearing capacity and stiffness of the structure to decrease slowly, facilitating the redistribution of internal forces and stable stress distribution in the structure.

[0032] 6. In the application of the X-shaped buckling-restrained brace of the present invention, when a large axial force is required to meet the bearing capacity requirements, the brace section is usually wide. After separating the built-in brace in one direction into two built-in steel plate braces, it can not only alleviate the sudden drop in bearing capacity caused by the tensile fracture of the built-in brace in one direction, but also arrange additional restraint members and tensile bolts between the two built-in braces in each direction, reduce the bolt spacing of the assembly restraint members in the central rotation area, enhance the local bending resistance of the restraint members in the central rotation area, avoid local bending failure, and further improve the ductility of the brace. Attached Figure Description

[0033] Figure 1 This is an exploded view of the X-shaped buckling-resistance brace used in this invention with slotted steel plate support;

[0034] Figure 2 This is an exploded view of the X-shaped buckling-resistance brace used in this invention with slab steel plate support;

[0035] Figure 3 This is a schematic diagram of the assembly of the first structure of the present invention, which consists of seven layers from the back to the front.

[0036] Figure 4 This is a schematic diagram of the assembly of the second structure of the present invention, which consists of seven layers from the back to the front.

[0037] Figure 5 This is a schematic diagram of the first structure of the present invention after assembly and installation on a steel beam;

[0038] Figure 6 This is a schematic diagram of the second construction method of the present invention after assembly and installation on a steel beam;

[0039] Figure 7 This is a schematic diagram of the first structure of the present invention after assembly, used to illustrate and explain the position of the "axial clearance" of the structure.

[0040] Figure 3 and Figure 4The layers are arranged from left to right, starting with the first layer and continuing to the last layer.

[0041] In the diagram, 1. First slotted support plate; 2. Second slotted support plate; 3. Slotted stiffening rib; 4. Long slot; 5. Slotted constraint strip in one direction; 5-1. Continuous perforated strip on the outer side of the support; 5-2. Perforated strip in the middle of the inner side of the support; 5-3. Perforated strip at the end of the inner side of the support; 6. Slotted constraint strip in two directions; 7. Thin steel plate in one direction of slotted constraint; 7-1. Thin steel plate with a broken perforation on the outer side of the support; 7-2. Thin steel plate with a broken perforation in the middle of the inner side of the support; 7-3. Slotted strip at the end of the inner side of the support; 8. Thin steel plate in two directions of slotted constraint; 9. The structure comprises: 9-1, 9-2, 9-3, 9-4, 9-5, 9-6, 9-7, 9-8, 9-9, 9-10, 9-11, 9-2, 9-3, 9-4, 9-5, 9-12, 9-13, 9-14, 9-15, 9-16, 9-17, 9-18, 9-19, 9-19. The slits are: 9-1, 9-2, 9-3, 9-4, 9-10, 9-19, 9-10, 9-11, 9-2, 9-12, 9-13, 9-14, 9-15, 9-16, 9-17, 9-18, 9-19, 9-19. The slits are: 9-1, 9-2, 9-19, 9-10, 9-19, 9-10, 9-11, 9-12, 9-13, 9-14, 9-15, 9-16, 9-17, 9-18, 9-19, 9-19, 9-19, 9-10 ...9, 9-10, 9-19, 9-10, 9-19, 9-19, 9-10, 9-19, 9-19, 9-10, 9-19, 9-19, Detailed Implementation

[0042] Specific implementation method one: Combining Figures 1 to 7 This embodiment describes an X-shaped buckling-resistance brace with internally arranged parallel strip steel plates, comprising internal steel plate supports and restraint steel members. The internal steel plate supports are arranged in two staggered directions and are not connected in the middle. The restraint steel members are laid outside the internal supports and are rotatably connected in the central staggered area. The internal steel plate supports are slotted steel plate supports or strip steel plate supports. A gap is left between the internal steel plate supports and the restraint steel members along the axial direction and in the plate thickness and width directions.

[0043] In this embodiment, "axial clearance" refers to the length direction of the support. It is located between the end of the stiffening rib of the built-in steel plate support and the end slot of the restraining steel member (e.g., Figure 1 The stiffening rib 3 and the slotted end slots of the slotted back constraint skeleton 9 and the slotted front constraint skeleton 10 are used to ensure that the support can deform freely axially under tension / compression, preventing the constraint members from participating in axial force. It also prevents the constraint members from yielding due to the squeezing of the stiffening ribs against the edge of the slots during support deformation.

[0044] There are two locations for the "axial clearance": one is located "between the end of the stiffening rib of the built-in steel plate support and the end slot of the restraining steel member"; the other is located within the slot of the slotted steel plate support, "with the two inner end slotted strips (7-3) located on both sides of the thin steel plate (7-2) with a broken opening in the middle of the inner side of one support". The axial clearance is left between each end slotted strip (7-3) and the thin steel plate (7-2) with a broken opening in the middle (e.g.) Figure 7 (As shown).

[0045] In this embodiment, the "plate thickness gap" refers to the direction perpendicular to the plane of the steel plate. This plate thickness gap is created using a perforated thin steel plate, and the gap is located between the inner surface of the plate supporting the built-in steel plate and the inner surface of the restraining steel members on both sides of the plate thickness that it may contact. Its function is to prevent the axially compressed built-in steel plate support from compressing the restraining members on both sides of the plate thickness direction as it thickens along its own thickness direction, thereby avoiding damage to the restraining members due to compression, ensuring that the deformation of the built-in steel plate support along the plate thickness caused by the Poisson effect is not restricted, and ensuring that the built-in steel plate support independently bears the axial load along the axial direction. At the same time, an appropriate plate thickness gap also helps to limit the amplitude of multi-wave buckling deformation in the plate thickness direction.

[0046] In this embodiment, the "plate width gap" refers to the gap along the width of the steel plate. It is located between the side of the built-in steel plate support and the strips or frame of the restraining steel members (e.g., between the two sides of the long slot 4 of the slotted support and the continuous perforated strip 5-1 on the outer side of the support, or the perforated strip 5-2 in the middle of the inner side of the support). Its function is to prevent the axially compressed built-in steel plate support from widening along its own width direction and compressing the restraining members on both sides of the plate width direction, thereby avoiding damage to the restraining members due to compression, ensuring that the deformation of the built-in steel plate support along the plate width caused by the Poisson effect is not restricted, and ensuring that the built-in steel plate support independently bears the axial load. At the same time, a suitable plate width gap also helps to limit the amplitude of multi-wave buckling deformation in the plate width direction.

[0047] In summary, the purpose of setting the aforementioned gap in this embodiment is as follows: 1. Mechanical decoupling: The gap isolates the force path between the constraint member and the built-in support, ensuring that only the support bears the axial force, while the constraint member only provides lateral constraint. 2. Deformation adaptation: It allows the support to be freely tensile and compressive during earthquakes, restricts large-scale multi-wave buckling deformation of the support, and at the same time, the constraint member remains elastic. 3. Maintainability: The gap facilitates the disassembly and replacement of the built-in support, and even allows the application of materials such as high-temperature resistant and corrosion-resistant grease within the gap to protect the built-in steel plate support, which meets the "maintainability" advantage emphasized in the patent.

[0048] This invention provides two types of assembled X-shaped buckling-restrained bracing structures with two-way internally built-in parallel strip steel plates and externally laid rotatable restraining steel members with staggered overlaps in the middle. The first type is a structure with internally built-in two-way slotted steel plate support (first structure); the second type is a structure with internally built-in two-way strip steel plate support (second structure).

[0049] The first type of construction (with built-in two-way slotted steel plate support) is shown below. Figure 1 It consists of two built-in slotted steel plate supports and restraining steel components in two directions. Its main components include: two built-in slotted steel plate supports and restraining steel components laid outside the supports. The two built-in slotted steel plate supports are identical, each with steel plate stiffening ribs at both ends. The stiffening ribs at both ends are of the same size and welded to the steel plate supports. The two slotted steel plate supports in two directions are not connected to each other and are arranged in an X-shape. Each slotted steel plate support is made from a single piece of steel plate with a long slot cut in the middle and stiffening ribs welded to both ends. The centerline of the slot width and the centerline of the stiffening rib thickness coincide with the axis of the entire support. Each slotted end of each slotted steel plate support is welded with an inner end slotted restraining strip. During manufacturing, the inner end slotted restraining strip is locally welded to the steel plate support in a plane (the weld is located in the middle of the width of the plate at the end of the slotted restraining strip, and the weld length is approximately one-third of the width of the slotted restraining strip), and the weld surface is ground flush with the steel plate surface.

[0050] In the constrained steel member, the perforated constrained steel plate has slots at both ends and three rows of holes along its length. Only one large bolt hole, with a diameter no smaller than the others, is located in the middle row, thus strengthening the connection and local bending resistance of the constrained member's middle section. The perforated pad also has three rows of holes along its length, a slot at one end, and a broken-line cross-section at the other end. The broken-line cross-section facilitates rotation in the middle while minimizing any reduction in its lateral constraint on the internal support in the middle. The end slots of the perforated constrained steel plate and the perforated pad have the same dimensions.

[0051] For the X-shaped buckling-restrained brace of structure one, its composition can be divided into seven layers from the back to the front. The plate thickness of the steel plate brace and the perforated restraint steel plates and perforated pads of the second, third, fifth, and sixth layers are all the same. The thickness of the perforated restraint steel plates in the first and seventh layers can be the same as or different from that of the second, third, fifth, and sixth layers. When a greater bending resistance is required from the restraint members, in addition to increasing the thickness of the perforated restraint steel plates in the first and seventh layers, the perforated restraint steel plates in the first and seventh layers can also be replaced with cross-sectional forms with greater bending stiffness, such as perforated restraint channel steel.

[0052] Taking the first and seventh layers using perforated restrained channel steel as an example, the slotted steel plate supports in both directions are placed in the third and fifth layers, respectively. Within each layer, the steel plate supports and restrained steel members of the same plate thickness are arranged coplanarly. The fourth layer consists of all thin restrained steel members, all with the same plate thickness, placed coplanarly within the same layer to allow for a gap along the thickness direction of the slotted steel plate supports between the restrained steel members and the two-way slotted steel plate supports. The perforated restrained steel plates and perforated pads in each of the second and sixth layers also have the same plate thickness and are placed coplanarly. At the same bolt passage location, the hole diameter in the restrained steel members of each layer is the same.

[0053] Depend on Figure 1 It is known that, along each support direction, the outer surface of each layer of constraint members is flush with the outer surface along the width direction of the steel plate support. Inside the support, a gap needs to be left between the constraint members and the support along the width direction of the steel plate support. The gap amount can be determined by leaving approximately 0.5mm for every 50mm of the steel plate support width on each side of the slotted support (the gap amount on one side of the steel plate support on each side of the slot). The slot depth of the end slotted steel members in the constraint members (including the perforated constraint steel plate, perforated pad, and perforated constraint channel steel) must ensure that the end of the support stiffening rib and the inner end of the slot do not experience compression along the support axis when the support undergoes the expected maximum axial compressive deformation. The slot width should be 10-15mm larger than the thickness of the support stiffening rib and ensure that the connection weld between the stiffening rib and the steel plate support does not touch the edge of the slot along the width direction of the steel plate support. The dimensions of each slot on the slotted constraint strip and the thin slotted strip on the inner end of the support must ensure that the bolt shank within the slot does not compress against each end of the slot along the support's axial direction when the support undergoes its expected maximum axial tensile and compressive deformation. The width of the slot can be 1-2 mm larger than the bolt diameter. Simultaneously, an axial clearance must be maintained between the slotted constraint strip at the inner end of the support and the perforated constraint strip in the middle of the inner side of the support to prevent mutual axial compression between the two strips when the inner steel plate support shaft is compressed for a short period. Within the same layer, the dimensions of the broken-line section of the perforated pad and the closest distance (5-10 mm) between the end of the broken-line section and the edge of the perforated constraint steel plate must be determined based on the mutual rotation requirements between the supports in both directions. The fourth layer of thin steel plate is used to leave a gap between the steel plate support and the restraining steel member along its thickness direction. The thickness of the thin steel plate is determined by leaving about 0.4 mm for every 10 mm of the thickness of the steel plate support (equivalent to 0.2 mm on each side of the thickness direction of the steel plate support).

[0054] The second type of construction (with built-in bidirectional segmented steel plate support) is shown below. Figure 2It consists of four built-in slab steel plate supports in two directions and restraining steel components. Its main components include: four built-in slab steel plate supports and restraining steel components laid on the outside of the supports. The four built-in slab steel plate supports are identical, each with steel plate stiffening ribs at both ends. The stiffening ribs at both ends are of the same size and welded to the steel plate supports. The four slab steel plate supports in both directions are not connected to each other and are arranged in an X-shape. Each slab steel plate support is made from a single piece of steel plate with stiffening ribs welded to both ends. The centerline of the stiffening rib plate thickness coincides with the axis of each slab steel plate support.

[0055] In the constrained steel member, the perforated constrained steel plate has slots at both ends and three rows of holes along its length. Only one large bolt hole, with a diameter no smaller than the others, is located in the middle row, thus strengthening the connection and local bending resistance of the constrained member's middle section. The perforated pad also has three rows of holes along its length, a slot at one end, and a broken-line cross-section at the other end. The broken-line cross-section facilitates rotation in the middle while minimizing the reduction in its lateral constraint on the internal support in the middle. The end slots of the perforated constrained steel plate and the perforated pad have the same dimensions, and two slots are provided at each end.

[0056] For the X-shaped buckling-restrained brace of structure two, it can be divided into seven layers from the back to the front. The plate thickness of the steel plate brace and the perforated restraint steel plates and perforated pads of the second, third, fifth, and sixth layers are the same. The thickness of the perforated restraint steel plates in the first and seventh layers can be the same as or different from that of the second, third, fifth, and sixth layers. When a greater bending resistance is required from the restraint members, in addition to increasing the thickness of the perforated restraint steel plates in the first and seventh layers, the perforated restraint steel plates in the first and seventh layers can also be replaced with cross-sectional forms with greater bending stiffness, such as perforated restraint channel steel.

[0057] Taking the first and seventh layers using perforated restrained channel steel as an example, the slab steel plate supports in both directions are placed in the third and fifth layers respectively. Within each layer, the steel plate supports and restrained steel members of the same plate thickness are arranged coplanarly. The fourth layer consists of all thin restrained steel members, all with the same plate thickness, placed coplanarly in the same layer to allow for a gap between the restrained steel members and the slab steel plate supports in both directions along the thickness direction of the slab steel plate supports. The perforated restrained steel plates and perforated pads in each of the second and sixth layers also have the same plate thickness and are placed coplanarly. At the same bolt passage location, the diameter of the holes in the restrained steel members in each layer is the same.

[0058] Along the axial direction of the two slab supports parallel to each direction, the constraint members of each layer are flush with the outer surface along the width direction of the steel plate support. Inside the support, a gap needs to be left between the constraint member and the support along the width direction of the steel plate support. The gap on each side of the slab support can be determined by leaving approximately 0.5mm for every 50mm of the width of each slab steel plate support. The groove depth of the end slotted steel members in the constraint members (including perforated constraint steel plates, perforated pads, and perforated constraint channel steel) must ensure that the end of the support stiffening rib and the inner end of the groove do not compress along the support axis when the support undergoes the expected maximum axial compressive deformation. The width of each groove should be 10-15mm larger than the thickness of the support stiffening rib and ensure that the connection weld between the stiffening rib and the steel plate support does not touch the edge of the groove along the width direction of the steel plate support. Within the same layer, the dimensions of the broken section of the perforated pad and the closest distance (which can be 5-10mm) between the end of the broken section and the edge of the perforated constraint steel plate need to be determined based on the mutual rotation requirements between the supports in the two directions. The fourth layer of thin steel plate is used to leave a gap between the steel plate support and the restraining steel member along its thickness direction. The thickness of the thin steel plate is determined by leaving about 0.4 mm for every 10 mm of the thickness of the steel plate support (equivalent to 0.2 mm on each side of the thickness direction of the steel plate support).

[0059] Furthermore, for the second configuration, both the first group of strip support plates 11 (containing two strip supports) and the second group of strip support plates 12 (containing two strip supports) are made of the same material. Alternatively, the first and third strip supports can be made of the same material, while the second and fourth strip supports can be made of a different material. This maintains a balance of axial forces in both directions and is more conducive to preventing the four supports from breaking simultaneously, further improving the ductility of the entire X-shaped buckling-restrained brace.

[0060] Specific Implementation Method Two: Combining Figures 1 to 2 In this embodiment, the built-in steel plate support and the middle overlapping area of ​​the constraint steel member are rotatably connected by bolts without preload.

[0061] This configuration enables relative rotation of the two-directional constraint members: adapting to angle changes: under horizontal loads, the angle between the two built-in supports in the X-shaped brace will dynamically change (such as reciprocating deformation during an earthquake). The bolt without preload allows the constraint steel members to rotate freely in the central overlapping area, avoiding bending or stress concentration in the constraint members caused by rigid connections. It eliminates rotational constraints: excessive bolt preload restricts rotation, causing the constraint members to bear additional bending moments and fail prematurely. It improves the local bending resistance of the constraint members in the rotation area: by using a large bolt without preload to ensure that the constraint steel members in both directions can rotate relative to each other, it strengthens the joint working capacity of the front and back constraint steel members in the central area, further improving the local bending bearing capacity of the constraint members and preventing yielding or local failure of the constraint members. It releases rotational stress: traditional fixed connections or preloaded bolts generate shear forces or bending moments on the constraint members when the support deforms. However, this invention, through a non-preloaded connection, allows the constraint members to only provide lateral constraints and not participate in axial force, ensuring that they remain in an elastic state. Protecting the central region: The central region is the most complex area for stress in the X-shaped support. The rotatable design disperses the deformation concentration effect, preventing tearing or shearing damage to the steel plates around the bolt holes. Ensuring free axial deformation of the built-in support: It does not interfere with the energy dissipation mechanism: The built-in support needs to dissipate energy through axial tensile and compressive yielding. If the restraint member's movement is restricted by the bolt preload, it will hinder the free deformation of the support and reduce energy dissipation efficiency. Maintaining clearance function: Untightened bolts allow the restraint member to slide slightly with the deformation of the built-in support, ensuring that the reserved axial clearance (such as the gap between the slot and the stiffening rib) is always effective and avoiding compression. Simplifying assembly and maintenance for easy disassembly: Untightened bolts are easier to disassemble and assemble, meeting the "replaceable" design goal of this invention. Reducing friction effects: The central overlapping surface is coated with grease, and the untightened bolts reduce frictional resistance during rotation, avoiding wear. Enhancing overall stability: Dynamically coordinating deformation: During an earthquake, the deformation of the supports in the two directions is asynchronous. The rotatable connection allows the restraint member to adapt to the deformation differences in real time, avoiding local damage caused by forced coordinated deformation. Other components and connection relationships are the same as in Specific Implementation Method 1.

[0062] The above design of this embodiment achieves the following through the "rotatable non-pre-tightening connection" in the central interlocking region: mechanical decoupling between the constraint member and the built-in support; balance between the free deformation of the support and the continuity of the constraint; effective release of complex stress in the middle, significantly improving the ductility and durability of the support.

[0063] Specific implementation method three: Combining Figure 1In this embodiment, when the built-in steel plate support is a slotted steel plate support, the built-in steel plate support includes a slotted first support plate 1, a slotted second support plate 2, and slotted stiffening ribs 3. Both the slotted first support plate 1 and the slotted second support plate 2 have long slots 4 in the middle along their length direction, and the slotted first support plate 1 and the slotted second support plate 2 are arranged alternately. Both ends of the slotted first support plate 1 and the slotted second support plate 2 are welded with slotted stiffening ribs 3.

[0064] This design achieves precise energy dissipation: concentrated plastic deformation in the long groove area efficiently dissipates seismic energy; natural restraint: staggered arrangement replaces welded restraint clips, avoiding stress concentration; end stability: stiffening ribs ensure reliable load transfer path and prevent local instability; coordinated deformation: clearance fit with restraint components ensures axial deformation freedom. Other components and connections are the same as in specific implementation method one or two.

[0065] In this embodiment, the slotted design (long slot 4) plays the following roles: (1) Forming a clear yield section: The long slot 4 is opened in the middle of the slotted first support plate 1 and the slotted second support plate 2, which weakens the cross section of the area and makes it a plastic section (yield section) of the support. (2) Under seismic load, the long slot area preferentially undergoes plastic deformation and dissipates energy, while the stiffening rib area (elastic section) at both ends remains stable, avoiding overall instability. (3) Uniform stress distribution: The symmetrical design of the long slot avoids stress concentration caused by abrupt changes in the cross section, ensuring uniform deformation of the yield section along the axial direction and improving hysteresis performance.

[0066] The staggered arrangement in this embodiment serves the following purposes: (1) Natural limiting constraint components: The slotted first support plate 1 and the slotted second support plate 2 are arranged in an X-shape, with the steel plates in both directions interlocking in the intersection area. The staggered arrangement of the steel plates provides physical limitation for the external constraint steel components, preventing the constraint components from sliding along the support axis (no additional welding limit clips are required). (2) Enhanced rotation coordination in the middle: The staggered design allows the supports in both directions to deform independently in the middle area, adapting to the angle change through the rotation structure without pre-tightened bolts, reducing mutual interference.

[0067] The function of the slotted stiffening rib 3 used in this embodiment is: (1) End rigidity enhancement: The stiffening rib is welded to both ends of the steel plate support, which significantly improves the bending stiffness of the end section and ensures that the elastic section does not buckle locally when under stress. (2) Transmission of axial load: The stiffening rib, as a transition component connecting the node and the main body of the support, uniformly transmits the axial force from the frame beam to the yield section (long slot area) of the support. (3) Gap control function: The stiffening rib thickness and the end slot of the restraint steel member are reserved with a gap (10-15mm) to ensure that the stiffening rib does not contact the slot when the support is under pressure, and to avoid the restraint member participating in the axial force.

[0068] This embodiment can produce a synergistic effect with the constraint member: (1) Clearance fit: A clearance is reserved between the slotted steel plate and the constraint steel member along the plate thickness direction (0.4mm for every 10mm of plate thickness) to ensure that the axial deformation of the support is not hindered by the friction of the constraint member. (2) Limitation of multi-wave buckling amplitude: When the support is under compression, the long slot area undergoes multi-wave bending deformation under the constraint of the hole wall of the constraint member. The above-mentioned appropriate clearance can prevent the built-in energy-consuming steel plate from premature fatigue fracture due to large-scale multi-wave instability.

[0069] Specific implementation method four: Combination Figure 1 In this embodiment, when the built-in steel plate support is a slotted steel plate support, the constraint steel components include a slotted constraint strip 5 in one direction, a slotted constraint strip 6 in another direction, a thin steel plate 7 in one direction, a thin steel plate 8 in another direction, a slotted back constraint frame 9, and a slotted front constraint frame 10. The thin steel plate 7 in one direction forms slotted constraint one after being installed on the slotted constraint strip 5. The thin steel plate 8 in another direction forms slotted constraint two after being installed on the slotted constraint strip 6. Slotted constraint one and slotted constraint two are respectively installed on the slotted first support plate 1 and the slotted second support plate 2. The slotted back constraint frame 9 and the slotted front constraint frame 10 are respectively installed on slotted constraint one and slotted constraint two from the back and the front, respectively.

[0070] This configuration, through the layered modular design of the constrained steel components (slats + thin steel plates + frame), achieves the following: continuous constraint: the front and back frame ensures lateral stability of the built-in support along its entire length; precise clearance: the thin steel plates control the plate thickness gaps, ensuring free deformation of the support; rotational adaptation: the untightened bolts in the middle allow for dynamic and coordinated deformation; maintainability: the prefabricated structure facilitates inspection and replacement. Other components and connections are the same as in any of the specific implementation methods one to three.

[0071] The layered modular design (constraint strips + thin steel plates) used in this implementation method serves the following purpose:

[0072] 1. Slotted constraint one / two-way constraint strips: (1) Provide main constraint stiffness: As the main load-bearing part of the constraint steel member, it forms an integral frame by high-strength bolt connection, providing continuous lateral constraint for the built-in support (slotted first support plate 1, slotted second support plate 2) to prevent the overall buckling of the support. (2) Slotted fit stiffening ribs: The slots at the ends of the constraint strips match the stiffening ribs 3 of the built-in support, with a reserved axial gap (10-15mm) to ensure that the axial deformation of the support is not restricted by the constraint member.

[0073] 2. Slotted constraint thin steel plate in one / two directions: (1) Auxiliary constraint and gap control: The thin steel plate is a thin steel plate installed on the constraint strip to accurately control the gap in the thickness direction between the built-in support and the constraint member (0.4mm is left for every 10mm of plate thickness) to avoid friction hindering the deformation of the support. (2) Reasonable control of multi-wave buckling: The thin steel plate and the constraint strip together form the hole wall, which limits the amplitude of multi-wave bending deformation when the support is under pressure and optimizes the energy consumption efficiency.

[0074] 3. Functions of the front and back constraint skeletons: (1) Continuity assurance: Traditional X-shaped supports have constraint breakage problems at the front or back, while the front and back constraint skeletons of this invention are all continuous components (such as perforated constraint steel plates or channel steel), ensuring that the built-in support obtains uniform lateral constraint throughout the entire length. (2) Enhanced bending resistance: The front and back constraint skeletons are connected to the central staggered overlapping area by high-strength bolts to form a closed box section (referring to the entire support section, in addition to the internal support, the external constraint components form a closed box section, in which the slotted area or strip area in the middle is a closed box section of two chambers), which significantly improves the overall bending resistance of the constraint components and prevents local punching and shear failure. (3) Rotation structure support: The front and back skeletons are connected in the central area by untightened bolts, allowing the constraint components in both directions to rotate relative to each other, adapting to changes in the support angle (such as reciprocating deformation during an earthquake).

[0075] 4. Synergistic effect with built-in support: (1) Dynamic deformation adaptation: The layered design of the constrained steel member (slats + thin steel plate + skeleton) and the gap fit with the built-in support ensure that when the support is subjected to tensile and compressive deformation, the constrained member only provides lateral constraint and does not participate in axial force. (2) Natural limiting function: The staggered arrangement of the built-in supports in two directions provides natural limiting for the constrained steel member through physical interlocking, avoiding the constrained member from sliding along the support axis (no need to weld the limiting card).

[0076] 5. Advantages of prefabricated design: Disassembly and maintenance: All restraint steel components are assembled with bolts, facilitating disassembly, inspection, or replacement of internal supports. Standardized production: Components such as slats, thin steel plates, and frames can be prefabricated in the factory and quickly assembled on-site, improving construction efficiency.

[0077] Specific Implementation Method Five: Combining Figure 1 This embodiment describes a slotted constraint unidirectional constraint strip 5 comprising two outer-side continuous perforated strips 5-1, an inner-side middle perforated strip 5-2, and two inner-side end perforated strips 5-3. The two outer-side continuous perforated strips 5-1 are arranged in parallel, the inner-side middle perforated strip 5-2 is located between the two outer-side continuous perforated strips 5-1, and the two inner-side end perforated strips 5-3 are located on both sides of the inner-side middle perforated strip 5-2.

[0078] This configuration uses slotted constraint slats as a constraint skeleton: providing lateral stiffness against buckling for the built-in support; serving as an assembly carrier: integrating thin steel plates, bolts, and other components to form a modular constraint layer; and acting as a deformation adapter: coordinating the axial deformation and rotational requirements of the support through end slots and a central rotating structure. This embodies the inventive concept of "prefabricated, rotatable, and continuously constrained" design. Other components and connections are the same as in any of the specific embodiments one through four.

[0079] Specific Implementation Method Six: Combination Figure 1 In this embodiment, the inner end perforated plate 5-3 of the support has two elongated holes, one of which partially overlaps with one end of the middle perforated plate 5-2 of the inner side of the support.

[0080] This design, through the partial overlap of the elongated holes, achieves: free deformation: dynamic adaptation of axial tension / compression and rotational deformation; stress release: preventing the constrained components from yielding due to forced coordinated deformation; and ease of construction: simplifying assembly precision requirements. This embodies the invention's balance between high-strength constraint and flexible deformation capabilities. Other components and connections are the same as in any of the specific embodiments one through five.

[0081] Specific implementation method seven: Combining Figure 1 This embodiment describes a slotted constraint thin steel plate 7 comprising four outer-side disconnected perforated thin steel plates 7-1, two inner-side middle-side disconnected perforated thin steel plates 7-2, and two inner-side end slotted strips 7-3. The two outer-side disconnected perforated thin steel plates 7-1 form a group along their length, and the two groups of outer-side disconnected perforated thin steel plates 7-1 are arranged in parallel. The two inner-side middle-side disconnected perforated thin steel plates 7-2 are located between the two groups of outer-side disconnected perforated thin steel plates 7-1, and the two inner-side end slotted strips 7-3 are located on both sides of one inner-side middle-side disconnected perforated thin steel plate 7-2.

[0082] With this configuration, although the slotted constraint thin steel plate 7 is a thin-layer component, it can achieve gap control, ensuring the freedom of support deformation; it can reasonably limit buckling, effectively controlling the amplitude of multi-wave instability; it can be assembled and adapted, improving the construction error tolerance rate; and it can protect the surface, reducing wear damage. This achieves "high-precision constraint" and "low-damage deformation." Other components and connections are the same as any one of the specific implementation methods one to six.

[0083] Specific implementation method eight: Combination Figure 1In this embodiment, the slotted back constraint frame 9 and the slotted front constraint frame 10 have the same structure. The slotted back constraint frame 9 includes a first perforated constraint steel plate 9-1, two first perforated pads 9-2, a second perforated constraint steel plate 9-3, and two second perforated pads 9-4. The two first perforated pads 9-2 are installed on the inner side of the first perforated constraint steel plate 9-1 to form a first back constraint frame, and the two second perforated pads 9-4 are installed on the inner side of the second perforated constraint steel plate 9-3 to form a second back constraint frame. The first back constraint frame and the second back constraint frame are arranged alternately and installed on the slotted constraint one-direction constraint strip 5 and the slotted constraint two-direction constraint strip 6. The opposite ends of the two first perforated pads 9-2 and the two second perforated pads 9-4 are zigzag-shaped.

[0084] With this configuration, this implementation achieves fully enclosed constraint, eliminating the risk of support buckling; it integrates rotational and bending resistance, making the middle section both flexible and strong; and it uses prefabricated force transmission, achieving a balance between convenient construction and mechanical performance. Other components and connections are the same as any one of the specific implementation methods one through seven.

[0085] The specific effects of this implementation method are as follows:

[0086] 1. Provides fully enclosed lateral restraint:

[0087] (1) Functional realization: The front and back constraint skeleton (9, 10) serves as the outermost layer of the constraint steel component. It is connected by high-strength bolts to form a closed box section, which completely encloses the built-in support (1 / 2 of the slotted steel plate).

[0088] (2) Technical aspects: Prevent the built-in support from buckling or twisting under pressure; ensure that the support has continuous and uniform lateral restraint throughout its entire length (including the central intersecting area).

[0089] 2. Enhance the bending resistance of the central rotation area:

[0090] (1) Key structural design: The front and back frames are connected by large-diameter bolts that are not pre-tightened in the middle of the overlapping area, allowing the two-way constraint members to rotate relative to each other; the continuity of the frame and the box-shaped section significantly improve the local bending stiffness of the area, avoiding punching shear or local bending failure caused by the breakage of the constraint in the middle of the traditional X-shaped support.

[0091] (2) Earthquake adaptability: When the support angle changes dynamically during an earthquake, the frame releases stress through rotation and maintains its elastic state.

[0092] 3. Achieve modular assembly of the constraint system:

[0093] (1) Layered assembly core: The back frame 9 and the front frame 10 are the outermost layers, which are quickly connected to the middle layer (constraint strips, thin steel plates) by bolts; support non-destructive disassembly, which is convenient for maintenance or replacement of internal supports.

[0094] (2) Standardized production: The frame can be prefabricated using hot-rolled steel plates or channel steel, and assembled on site after opening / grooving, which improves construction efficiency.

[0095] 4. Optimize load transfer path:

[0096] (1) Mechanical synergy: The front and back frames are aligned with the stiffening ribs 3 of the built-in support, so that the shear force from the frame beam is evenly transmitted to the entire support system through the connection of the support ends.

[0097] Specific Implementation Method Nine: Combining Figure 2 In this embodiment, when the built-in steel plate support is a slab steel plate support, the built-in steel plate support includes a first group of slab support plates 11, a second group of slab support plates 12, and slab stiffening ribs 13. Two slab stiffening ribs 13 are respectively installed at both ends of the first group of slab support plates 11 and the second group of slab support plates 12.

[0098] This configuration achieves safety redundancy in this implementation: segmentation prevents the instantaneous failure of the entire steel plate, improving seismic reliability; precise energy dissipation: stiffening ribs define the elastic / yield sections, optimizing the distribution of plastic deformation; and collaborative constraint: it forms an efficient interaction mechanism with external constraint components. This reflects the invention's ability to address high load-bearing capacity requirements and fracture control. Other components and connections are the same as in any of the specific implementations one through eight.

[0099] The functions of the slit support plate in this embodiment are: (1) Slit energy dissipation design, with two independent slit support plates in each direction (such as the first group 11 containing two plates), achieved through slit construction; (2) Successive fracture control: when a single support breaks, the other can still maintain part of the bearing capacity, avoiding a sharp drop in lateral resistance after the traditional integral support breaks; (3) Differentiated material configuration: the 1 / 3 and 2 / 4 of the slit support can use steels with different strengths or ductility (such as a combination of high and low yield points), further optimizing the fracture sequence and energy dissipation gradient; (4) Mechanical advantages of staggered arrangement: the slit supports in the two directions are arranged in an X-shape, forming a natural limit; (5) replacing the traditional welded limit card, avoiding stress concentration; (6) the cross area is physically fitted to constrain the axial sliding of the external constraint components.

[0100] The functions of the slit stiffeners 13 in this embodiment are: (1) end rigidity enhancement: stiffeners 13 are welded to both ends of each slit support plate, which significantly improves the bending stiffness of the end section and ensures that the elastic section (non-yielding section) does not buckle locally when under stress; (2) a 10-15mm gap is reserved between the thickness of the stiffeners and the groove of the constraint steel member to avoid the constraint member from participating in axial stress; (3) efficient load transfer: the stiffeners serve as transition components between the support and the frame beam / column connection node, and uniformly transfer the external load to the yielding section (the middle area without stiffeners) of the slit support plate; (4) the welds avoid the edge of the constraint groove to prevent stress concentration.

[0101] The coordination mechanism between this implementation method and the constrained steel member is as follows: (1) Gap fit optimization: A 0.5mm gap is left every 50mm along the width direction between the slit support plate and the constrained steel member to ensure free axial deformation; the slit design allows for the arrangement of additional constrained strips between the two supports, reducing the bolt spacing and enhancing the bending resistance in the middle. (2) Multi-wave buckling guidance: The hole wall of the constrained steel member restricts the buckling mode of the slit support plate under compression, so as to effectively control the amplitude of multi-wave bending deformation, prevent premature low-cycle fatigue fracture due to large bending, and mainly dissipate seismic energy through repeated axial plastic deformation.

[0102] Specific Implementation Method Ten: Combining Figure 2 In this embodiment, when the built-in steel plate support is a slab steel plate support, the constraint steel components include a slab support first-direction constraint strip 14, a slab support second-direction constraint strip 15, a slab support first-direction thin steel plate 16, a slab support second-direction thin steel plate 17, a slab back constraint frame 18, and a slab front constraint frame 19. The slab support first-direction constraint strip 14 is installed on the first group of slab support plates 11. The slab support first-direction thin steel plate 16 is a split thin steel plate and is installed on the slab support first-direction constraint strip 14. The slab support second-direction constraint strip 15 and the slab support second-direction thin steel plate 17 are respectively installed on the left and right sides of the second group of slab support plates 12. The slab back constraint frame 18 and the slab front constraint frame 19 are respectively installed on the slab support first-direction thin steel plate 16 and the slab support second-direction constraint strip 15.

[0103] Combination Figures 1 to 7 The specific implementation process of this invention is explained as follows:

[0104] 1) Fabrication of built-in slotted steel plate supports or slit steel plate supports

[0105] For structure one, the steel plates required for fabricating the slotted steel plate supports and stiffening ribs are cut and prepared, and the steel plate supports are also slotted. There is one slotted steel plate support in each direction, with two slotted steel plate supports in total arranged in an X-shape, without connection in the middle. In actual fabrication, the slotted steel plate supports and stiffening ribs can be cut from the same steel plate.

[0106] The slotted steel plate support is planed, including milling the edges of the internal slotted areas and smoothing the edges of the stiffening ribs. The slotted steel plate support and stiffening ribs are then welded together. The unslotted sections of the slotted steel plate support (including the sections with stiffening ribs) are elastic sections, while the slotted sections are yielding sections. Furthermore, the slotted constraint strips at the inner end of the processed support are welded coplanarly to the steel plate support (the weld is located at the midpoint of the width of the slotted constraint strip at its end, and the weld length is approximately one-third of the width of the slotted constraint strip), and the weld surface is ground flush with the steel plate surface.

[0107] For structure two, the steel plates required for the fabrication of the slab steel plate supports and stiffening ribs are cut and prepared. Two slab steel plate supports are prepared in each direction, resulting in a total of four internal slab steel plate supports arranged in an X-shape, without connection in the middle. In actual fabrication, the slab steel plate supports and stiffening ribs can be prepared from the same steel plate.

[0108] The slit steel plate supports are planed, and the stiffening ribs are trimmed at the edges. Then, the slit supports and stiffening ribs are welded together. The sections of the slit support with stiffening ribs are considered elastic sections, while the sections without stiffening ribs are considered yielding sections.

[0109] 2) Fabrication of restraint steel components

[0110] First construction:

[0111] The perforated constraint steel plates, perforated pads, perforated constraint strips on the outer side of the support, perforated constraint strips on the inner middle side of the support, slotted constraint strips on the inner end of the support, continuous thin perforated strips on the outer side of the support, thin perforated strips on the inner middle side of the support, thin slotted strips on the inner end of the support, and discontinuous thin perforated strips on the outer side of the support (each consisting of two sections) and discontinuous thin perforated strips on the inner middle side of the support are all cut and prepared according to requirements, and perforations and slots are made. The edges of the plates are then smoothed. The areas where the thickness of the perforated constraint strips on the inner middle side of the support and the slotted constraint strips on the inner end of the support can be made by grinding away half the thickness of the steel plate as required, or they can be formed by butt welding steel plates of different thicknesses together.

[0112] Second construction:

[0113] The steel plates with openings, the pads with openings, the outer opening restraint strips of the supports, the inner opening restraint strips of the supports, the outer continuous thin opening strips of the supports, the inner continuous thin opening strips of the supports, the outer broken thin opening strips of the supports (each including two sections), and the inner broken thin opening strips of the supports are all cut and prepared according to requirements, and holes and grooves are made, and the edges of the plates are smoothed.

[0114] The first and second constructions:

[0115] To ensure dimensional accuracy and facilitate precise assembly, the steel plate thickness of the restraint steel components in each layer is uniform; in actual fabrication, it is advisable to use the same steel plate for cutting. The steel plate supports and the perforated restraint steel plates and perforated pads in the second, third, fifth, and sixth layers are all made of steel plates of the same thickness; in actual fabrication, it is advisable to use the same steel plate for cutting. The thickness of the perforated restraint steel plates in the first and seventh layers can be the same as or different from that of the second, third, fifth, and sixth layers. When greater bending resistance is required from the restraint components, in addition to increasing the thickness of the perforated restraint steel plates in the first and seventh layers, the perforated restraint steel plates in the first and seventh layers can be replaced with perforated restraint channel steel or other cross-sectional forms with greater bending stiffness. The channel steel cross-section can be hot-rolled channel steel or channel steel composed of welded steel plates, with slots and holes cut into it. All thin restraint steel components in the fourth layer are made of steel plates of the same thickness; in actual fabrication, it is advisable to use the same thin steel plate for cutting and then cut with holes or slots.

[0116] 3) Gaps are left between the built-in slotted steel plate support or slit steel plate support and the X-shaped constraint steel components.

[0117] 4) Assembly of X-shaped buckling-restrained braces

[0118] First construction:

[0119] It consists of seven layers, and the assembly order, stacked from back to front, is as follows:

[0120] (1) Place the perforated constraint steel plate along the slotted support direction on a horizontal surface (when using perforated constraint channel steel, the web of the channel steel is on the upper side) to form the first layer.

[0121] (2) Place the second layer of constraint steel components (including the perforated pads along the direction of slotted support 2 and the perforated constraint steel plates along the direction of slotted support) on the first layer in a coplanar manner.

[0122] (3) Place the constraint steel members and steel plate supports of the third layer on the second layer in a plane (first place the slotted support 2 with the slotted constraint strips welded to the inner end of the support, then place the constraint strips with holes in the middle of the inner side of the support and the constraint strips with holes on the outer side of the support parallel to the direction of the slotted support 2, and place the perforated pad along the direction of the slotted support 1).

[0123] (4) Place the thin constraint steel members of the two slotted support directions of the fourth layer on the third layer in a coplanar manner.

[0124] (5) Place the fifth layer of constraint steel members and steel plate supports on the fourth layer in a plane (first place the slotted support 1 with the slotted constraint strips welded to the inner end of the support, then place the middle hole constraint strips of the support and the outer hole constraint strips of the support parallel to the direction of the slotted support 1, and place the hole pads along the direction of the slotted support 2).

[0125] (6) Place the sixth layer of constraint steel components (including the perforated pads along the direction of slotted support 1 and the perforated constraint steel plates along the direction of slotted support 2) on the fifth layer in a coplanar manner.

[0126] (7) Place the perforated constraint steel plate along the direction of slotted support 1 on the sixth layer (when using perforated constraint channel steel, the web of the channel steel is on the lower side) to form the seventh layer.

[0127] (8) To ensure correct positioning, during assembly, ensure that the bolt holes of each layer of constraint components are coaxial in each support direction corresponding to the same bolt position, and check the positioning of each layer of constraint steel components.

[0128] (9) After all the constraint steel components, the two built-in slotted supports, and the gap between the constraint steel components and the slotted constraints have been checked and adjusted correctly, the high-strength bolts are then installed and tightened (one high-strength bolt with a large bolt hole in the middle of the constraint component is not pre-tightened), thus completing the assembly of the entire first type of X-shaped support component.

[0129] Second construction:

[0130] It consists of seven layers, and the assembly order, stacked from back to front, is as follows:

[0131] (1) Place the perforated constraint steel plate along the direction of the third and fourth slit supports on a horizontal plane (when using perforated constraint channel steel, the web of the channel steel is on the upper side) to form the first layer.

[0132] (2) The second layer of constraint steel members (including the perforated pads along the direction of the third and fourth slab supports and the perforated constraint steel plates along the direction of the first and second slab supports) are placed coplanarly on the first layer.

[0133] (3) Place the constraint steel members and steel plate supports of the third layer on the second layer in a coplanar manner (first place the third and fourth slab supports, then place the inner and outer slab support constraint strips parallel to the direction of the third and fourth slab supports, and place the perforated pads along the direction of the first and second slab supports).

[0134] (4) Place the thin constrained steel members of the four strip support directions of the fourth layer on the third layer in a coplanar manner.

[0135] (5) Place the fifth layer of constrained steel members and steel plate supports on the fourth layer in a coplanar manner (first place the first slab support and the second slab support, then place the inner and outer slab support constrained plates parallel to the direction of the first and second slab supports, and place the perforated pads along the direction of the third and fourth slab supports).

[0136] (6) Place the sixth layer of constrained steel members (including the perforated pads along the first and second slab supports and the perforated constrained steel plates along the third and fourth slab supports) on the fifth layer in a coplanar manner.

[0137] (7) Place the perforated constraint steel plate along the direction of the first slit support and the second slit support on the sixth layer (when using perforated constraint channel steel, the web of the channel steel is on the lower side) to form the seventh layer.

[0138] (8) To ensure correct positioning, during assembly, ensure that the bolt holes of each layer of constraint members are coaxial in each support direction corresponding to the same bolt position, and check the positioning of each layer of constraint members.

[0139] (9) After all the restraint steel components, the four built-in strip supports, and the gap between the restraint steel components and the strip supports have been checked and adjusted correctly, the high-strength bolts are then installed and tightened (one high-strength bolt with a large bolt hole in the middle of the restraint component is not pre-tightened), thus completing the assembly of the entire second type of X-shaped support component.

[0140] If the support needs to be disassembled, the bolts can be loosened and the components can be removed in the reverse order of the installation described above.

[0141] Before assembly, the surface of the steel plate support is derusted. Then, high-temperature and aging-resistant grease is applied to the contact areas of the steel plate support surface and the interlocking constraint steel components in the middle. This reduces the friction between the steel plate support and the constraint components, as well as between the constraint components in the mutual rotation area, and prevents corrosion of the slotted or slit steel plate support.

[0142] Furthermore, the present invention comprises seven layers of restraining steel components on both sides, assembled using high-strength bolts to encapsulate two interlocking, non-connected slotted steel plate supports or slab steel plate supports in both directions. Notably, the restraining steel components in both directions can mutually support each other in the middle and also rotate relative to each other. Using steel plates significantly reduces the thickness of the restraining components, expanding the usable space. Stiffening ribs are welded to the ends of the built-in slotted steel plate supports or slab steel plate supports. Along each support axis, the restraining components are connected by three rows of bolts. In addition to the two rows of bolts at the edges, restraining strips and bolts are also installed within the slots of the slotted steel plate supports or between the slab steel plate supports, significantly improving the bending resistance and local punching shear capacity of the restraining components. Lubricant is applied to the contact surfaces of the restraining steel components in the central interlocking area to facilitate rotation between the restraining components in both directions. Each layer of restraining steel components can be made of hot-rolled steel plates or sections, avoiding additional welding processes. Perforated restraining steel components are connected using high-strength bolts. Along the axial direction of the steel plate support, the slots at both ends of the slotted components of the restraining steel members and the stiffening ribs at both ends of the corresponding supports have appropriate axial clearances, and the clearances at both ends are the same. It should also be noted that in the central overlapping area of ​​the restraining steel members in both directions, only one large-diameter high-strength bolt without preload is installed, and no other high-strength bolts with preload are installed. In the central overlapping area, the slotted steel plate supports or strip steel plate supports in both directions are not connected. In this way, the built-in steel plates and restraining members in both directions can rotate relative to each other within the plane of the support, while outside the support plane, the restraining members and steel plate supports in both directions can actually support each other.

[0143] The transmission relationship of the present invention is as follows:

[0144] Under horizontal earthquakes or wind action, when adjacent upper and lower floors experience relative horizontal lateral displacement, the assembled X-shaped buckling-restrained brace shifts horizontally in the reverse direction. During this horizontal lateral displacement, the built-in brace connected to the frame beam undergoes either compression shortening or tension elongation along the axial direction. When the brace is compressed, the axial gap between the stiffening ribs at both ends of the brace and the slotted components (perforated constraint steel plates (or even perforated constraint channel steel) and perforated pads) of the restraining steel member allows the brace to deform freely relative to the restraining steel member along the brace's axial direction. This makes the axial tensile and compressive deformation of the slotted steel plate brace or slab steel plate brace in both directions smoother during the horizontal lateral displacement of the brace. Simultaneously, the practice of leaving axial gaps between the upper and lower slots of the restraining steel member and the upper and lower stiffening ribs of the built-in brace facilitates the design principles and stress characteristics of providing normal bending resistance to the brace while ensuring smooth axial deformation of the built-in brace, minimizing axial pressure on the restraining member, and preventing yielding of the restraining member. Meanwhile, the constrained steel members of this invention employ a three-row bolt connection. In addition to the two rows of bolts at the edges, constrained strips and bolts are also installed within the slots of the slotted steel plate supports or between the stripped steel plate supports. This significantly improves the bending resistance and local punching shear bearing capacity of the constrained members, preventing the failure of the central constrained members in existing X-shaped buckling-restrained braces with central rotation. Under large earthquake loads, when the floor steel beams undergo plastic deformation and significant axial tensile or compressive deformation, the requirement for the mutual rotation capability between the two supports of the X-shaped buckling-restrained brace will further increase. The zigzag cross-section of the inner end of the perforated pad in this invention, and the distance between the end of the perforated pad and the edge of the perforated constrained steel plate, can satisfy this rotational deformation capability requirement through the central mutual rotation structure.

[0145] Because the X-shaped restraint steel members are laid on slotted or slit steel plate supports in two directions with gaps between them, when the X-shaped supports move horizontally, the built-in supports drive the restraint steel members to translate and rotate. The two built-in supports bear all horizontal forces. The restraint members provide lateral restraint to the built-in supports in the form of bending members. When the X-shaped restraint members can provide sufficient lateral restraint to the built-in supports, it ensures that the supports do not buckle under compression. Under horizontal reciprocating action, both built-in supports can yield under tension and compression and continue to bear loads. The mutual rotation structure of the restraint members makes the lateral deformation of the supports smoother and the stress distribution more reasonable, preventing the restraint members from yielding and failing. Furthermore, the restraint members are precisely assembled and laid on the staggered built-in supports using bolts. The staggered built-in supports in two directions form a natural limiting function for the X-shaped restraint members, facilitating precise construction and control of gap settings, and effectively controlling the placement of the restraint members on the supports. This avoids the current widely used practice of welding limiting clips to the built-in support, which leads to stress concentration and early low-cycle fatigue failure. It is conducive to achieving a more uniform cross-section of the support yield section and stress along the axial direction, and can further improve the ductility of the X-shaped buckling-restrained brace.

[0146] Combination Figures 1 to 6 Explanation of the working principle of this invention:

[0147] The X-shaped buckling-restrained brace, with its centrally staggered, rotatable steel components and built-in parallel slab steel plates, is essentially a novel type of buckling-restrained brace that uses built-in slab steel plates to support yield energy dissipation and provides lateral restraint through the assembly of X-shaped constraint steel components. It can be achieved through… Figure 1 and Figure 2 The X-shaped buckling-restrained brace is connected to the steel frame using methods such as welding the thick-end plates. A reasonable structure should ensure that the brace achieves the following working state: while utilizing mutual support to improve its overall compressive stability and bearing capacity, the adverse interactions between the two braces should be minimized as much as possible. Based on this consideration, the present invention leaves gaps along the support axis between the upper and lower slots of the restraint member and the upper and lower stiffening ribs of the built-in support. Large bolts without pre-tension are installed in the middle of the restraint member, passing through the slab steel plate support or channel steel plate support, to ensure that the restraint steel members in the two directions can rotate relative to each other. Continuous restraint steel members, such as continuously perforated restraint steel plates or perforated restraint channel steel, are used on both the front and back of the X-shaped brace. The built-in supports and restraint steel members in the two directions are then staggered and overlapped in the middle. Applying grease between the surfaces enhances the mutual support between the two buckling-restrained braces, improving the overall stability and bearing capacity of the buckling-restrained braces and further reducing the cross-sectional dimensions of the restraint members, making the design of X-shaped buckling-restrained braces more economical. At the same time, the axial clearance and the structure of mutual rotation in the middle ensure that the steel plate supports can smoothly undergo axial tensile and compressive deformation during the translation and rotation of the restraint members driven by the two built-in supports, and enable the restraint members to adapt to the rotational deformation requirements caused by the change in the included angle between the two supports in real time, avoiding yielding and failure of the restraint members.

[0148] Because of the gap between the built-in slab steel plate support and the constrained steel member, after the built-in slab steel plate support yields under pressure, it will undergo multi-wave bending deformation within the hole wall of the constrained steel member, thereby locally compressing the constrained steel member at the crests or troughs of the bending deformation. Both Structure 1 and Structure 2 of this invention utilize the spacing of the slab steel plate supports and the slotted space of the slotted steel plate supports in the central overlapping area to install a large bolt without preload. This ensures that the constrained steel members in both directions can rotate relative to each other, while simultaneously strengthening the joint working capacity of the front and back constrained steel members in the central area. This further improves the local bending bearing capacity of the constrained member and prevents local bending failure caused by the slab steel plate support undergoing multi-wave bending deformation around its weak axis and punching and shearing the constrained steel member. Compared to previous structures that used a large central disk for rotation, this invention does not use a central disk, which simplifies and facilitates the manufacture of the constraint components. It also reduces the central rotation area and decreases the bolt spacing along the support axis in the central staggered overlapping area of ​​the constraint components in each direction. This enhances the local bending resistance of the constraint components in the central rotation area and avoids local bending failure.

[0149] The restraining steel members in each direction should be continuous and provide continuous bending resistance to the built-in supports in that direction, thereby ensuring that the built-in supports receive continuous lateral support from the restraining steel members. In previous X-shaped buckling-restrained braces with central rotation, there was always a problem of poor continuity of the restraining members in the middle of one side of the front or back, resulting in potential vulnerabilities in the local restraint capacity of the main structure, making it prone to local bending failure under the punching and shearing action of the built-in supports. For the first and second structures of this invention, continuous restraining steel members such as perforated restraining steel plates or perforated restraining channel steels are used on both the front and back of the X-shaped brace, which are connected together by high-strength bolts, which can significantly improve the continuity and bending resistance of the restraining steel members.

[0150] The story shear force applied to the assembled X-shaped buckling-restrained braces is jointly borne by the compressive brace in one direction and the tension brace in the other direction in the form of axial force. Due to the staggered overlapping structure in the middle, the compressive brace can improve its overall compressive stability bearing capacity by receiving lateral support from the tension brace. When the assembled X-shaped buckling-restrained braces are subjected to story lateral displacement not exceeding the axial yield displacement of the corresponding brace, the built-in X-shaped brace does not yield and the brace is in an elastic state; when the inter-story lateral displacement exceeds the inter-story lateral displacement of the corresponding brace axial yield displacement, the built-in X-shaped brace enters the yielding stage, that is, energy is dissipated through the cumulative plastic development of the yielding section of the built-in X-shaped brace. The internal two-way slatted steel plate braces (including slotted steel plate braces) have a structure in which the upper and lower stiffening ribs are axially spaced along the brace and the middle of the restraint steel members can rotate relative to each other to ensure smooth axial tensile and compressive deformation and angle changes of the two braces, avoiding compression of the restraint steel members which would lead to yielding and failure of the restraint steel members, and ensuring that the slotted steel plate brace or slatted steel plate brace in the section with stiffening ribs and all restraint steel members are always in an elastic state.

[0151] When X-shaped buckling-restrained braces require large axial forces to meet load-bearing capacity requirements, to avoid a sudden and significant weakening of the brace's lateral resistance due to the fracture of the entire cross-section of the built-in brace in one direction, this invention employs slotted steel plate braces or slit steel plate braces. This breaks down the traditional single brace in each direction into two braces, facilitating the successive fracture of the brace cross-section. Thus, even if the brace fractures under tension, the smaller cross-sections of each fracture result in a smaller reduction in load-bearing capacity, contributing to a gradual decrease in the structure's lateral resistance and stiffness, and facilitating the redistribution of internal forces and stable stress distribution. In particular, for configuration two, besides using the same material for the first, second, third, and fourth slit braces, it is also possible to use the same material for the first and third slit braces, while using a different material for the second and fourth slit braces. This symmetrical arrangement of the slit braces in both directions maintains a balance of axial forces in both directions. Furthermore, when two built-in supports with different yield strengths and plastic deformation capabilities are used under stress in the same direction, it is easier to control the successive fracture of the support section, which is more conducive to achieving that the four strip supports do not fracture at the same time, and further improves the ductility of the entire X-shaped buckling-restrained brace.

[0152] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An assembled X-shaped buckling-resistance brace with internally arranged parallel strip steel plates of a centrally interlocking, rotatable steel component, characterized in that: It includes built-in steel plate supports and restraining steel components. The built-in steel plate supports are arranged in two staggered directions and are not connected in the middle. The restraining steel components are laid outside the built-in steel plate supports and are rotatably connected in the staggered overlapping area in the middle. The built-in steel plate supports are slotted steel plate supports. A gap is left between the built-in steel plate supports and the restraining steel components along the axial direction and in the direction of plate thickness and plate width. The built-in steel plate support includes a slotted first support plate (1), a slotted second support plate (2), and a slotted stiffening rib (3). The slotted first support plate (1) and the slotted second support plate (2) are both provided with long slots (4) in the middle of their length direction, and the slotted first support plate (1) and the slotted second support plate (2) are arranged alternately. The slotted first support plate (1) and the slotted second support plate (2) are both welded with slotted stiffening ribs (3). The constraint steel components include slotted constraint 1 direction constraint strip (5), slotted constraint 2 direction constraint strip (6), slotted constraint 1 direction thin steel plate (7), slotted constraint 2 direction thin steel plate (8), slotted back constraint skeleton (9) and slotted front constraint skeleton (10). The slotted constraint 1 direction thin steel plate (7) is installed on the slotted constraint 1 direction constraint strip (5) to form slotted constraint 1. The slotted constraint 2 direction thin steel plate (8) is installed on the slotted constraint 2 direction constraint strip (6) to form slotted constraint 2. Slotted constraint 1 and slotted constraint 2 are respectively installed on slotted first support plate (1) and slotted second support plate (2). Slotted back constraint skeleton (9) and slotted front constraint skeleton (10) are respectively installed on slotted constraint 1 and slotted constraint 2 from the back and front.

2. The X-shaped buckling-resistance brace with internally arranged parallel strip steel plates in the centrally interlocked rotatable steel component as described in claim 1, characterized in that: The interlocking areas between the built-in steel plate supports and the constrained steel components are rotatably connected by bolts without preload.

3. The X-shaped buckling-resistance brace with internally arranged parallel strip steel plates in the centrally interlocked rotatable steel component according to claim 2, characterized in that: The slotted constraint unidirectional constraint strip (5) includes two outer continuous perforated strips (5-1), an inner middle perforated strip (5-2), and two inner end perforated strips (5-3); the two outer continuous perforated strips (5-1) are arranged in parallel, the inner middle perforated strip (5-2) is located between the two outer continuous perforated strips (5-1), and the two inner end perforated strips (5-3) are located on both sides of the inner middle perforated strip (5-2).

4. The X-shaped buckling-resistance brace with internally arranged parallel strip steel plates in the centrally interlocked rotatable steel component as described in claim 3, characterized in that: Two elongated holes are provided on the inner end perforated strip (5-3) of the support, one of which partially overlaps with one end of the inner middle perforated strip (5-2) of the support.

5. The X-shaped buckling-resistance brace with internally arranged parallel strip steel plates in the centrally interlocked rotatable steel component according to claim 4, characterized in that: The slotted constraint thin steel plate (7) includes four thin steel plates with open holes on the outer side of the support (7-1), two thin steel plates with open holes in the middle of the inner side of the support (7-2), and two slotted strips at the ends of the inner side of the support (7-3). Two thin steel plates with open outer sides (7-1) are arranged in a group along the length direction. The two groups of thin steel plates with open outer sides (7-1) are arranged in parallel. Two thin steel plates with open inner sides (7-2) are located between the two groups of thin steel plates with open outer sides (7-1). Two slotted strips (7-3) at the ends of the inner sides of the supports are located on both sides of one of the thin steel plates with open inner sides (7-2).

6. The X-shaped buckling-resistance brace with internally arranged parallel strip steel plates in the centrally interlocked rotatable steel component according to claim 5, characterized in that: The slotted back constraint frame (9) and the slotted front constraint frame (10) have the same structure. The slotted back constraint frame (9) includes a first opening constraint steel plate (9-1), two first opening pads (9-2), a second opening constraint steel plate (9-3), and two second opening pads (9-4). Two first perforated pads (9-2) are installed on the inner side of the first perforated constraint steel plate (9-1) to form a first back skeleton, and two second perforated pads (9-4) are installed on the inner side of the second perforated constraint steel plate (9-3) to form a second back skeleton. The first back skeleton and the second back skeleton are arranged alternately and installed on the slotted constraint one-direction constraint strip (5) and the slotted constraint two-direction constraint strip (6). The opposite ends of the two first perforated pads (9-2) and the two second perforated pads (9-4) are zigzag-shaped.

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