Prefabricated stair concealed anti-seismic connecting joint and construction method thereof

Abstract

The application discloses an assembled stair hidden anti-seismic connecting joint and a construction method thereof, and the connecting joint is used for connecting a stair component and a main component into a whole, and comprises a shearing steel bar assembly and an adjusting assembly arranged on the main component, and a steel assembly arranged on the stair component; the steel assembly is detachably connected with the adjusting assembly; the shearing steel bar assembly, the steel assembly and the adjusting assembly are integrally poured with concrete to form the connecting joint; the steel assembly is used for transmitting the load of the stair component to the main component in the assembling stage, and transmitting the load of the stair component to the concrete and the shearing steel bar assembly after the concrete of the connecting joint reaches the design strength; the application can realize the active separation and orderly conversion of the stress system in the assembling stage and the using stage, realize the orderly conversion of the stress path, form the hidden whole anti-seismic connecting joint, and ensure the stress continuity and the ductility performance of the structure.

Description

Technical Field

[0001] This invention relates to the field of prefabricated building structure technology. More specifically, this invention relates to a concealed seismic-resistant connection node for prefabricated staircases and its construction method. Background Technology

[0002] With the widespread application of prefabricated construction in residential and public buildings, prefabricated staircases, as a highly standardized and important component, have gradually achieved factory production and on-site hoisting and installation. Staircases not only serve the function of pedestrian access but also constitute an important vertical traffic component within the overall structural system. Their connection nodes must meet multiple requirements, including vertical load-bearing capacity, horizontal restraint, and seismic performance. Especially in seismically fortified areas, staircase connection nodes must also possess good ductility and energy dissipation capacity to ensure the overall structural safety under seismic loads.

[0003] However, under the existing prefabricated construction model, an overall stress-bearing approach is adopted. Prefabricated staircase connection nodes often use methods such as sleeve grouting, post-cast concrete, or steel component connections to achieve overall structural stress. During the staircase hoisting stage, it is necessary to ensure that the nodes reach the design load-bearing capacity, which places high demands on the connection structure and construction precision, making construction difficult. The design focus of overall stress bearing is usually concentrated on the load-bearing capacity and seismic performance after completion, while insufficient attention is paid to the stress state during construction. Some nodes bear the load of the final reinforced steel system during the installation stage, lacking temporary stress transition structures. This causes the loads during construction and the design loads during the service stage to be superimposed in the same stress path, making it difficult to achieve phased control. This results in eccentric loads, impact loads, and installation disturbances generated during construction potentially acting directly on the final reinforced steel system, easily leading to stress concentration or micro-crack damage at the nodes, adversely affecting the later seismic performance.

[0004] Furthermore, most corbels connecting joints are exposed, with components directly visible from the interior or exterior facade, making it difficult to coordinate with the architectural space and facade aesthetics. Some steel corbels require corrosion and fireproofing maintenance during long-term service, increasing later operation and maintenance costs and management complexity. Moreover, technical solutions for prefabricated corbels often focus on strengthening the joint structure or connection design, such as increasing load-bearing capacity by adding exposed reinforcing bars. While this technology enhances the final load-bearing performance of the joint to some extent, it neglects the increased complexity and durability of the molds added during the prefabrication stage, making it economically unfeasible. Additionally, existing technologies for adjusting corbel elevation often rely on manual intervention or additional structures, lacking a systematic stress conversion mechanism, making it difficult to effectively eliminate assembly errors without increasing construction complexity. In particular, existing prefabricated corbels, once subjected to stress during the assembly stage, are usually unable to actively exit the main stress state after the structure is formed. This results in the stress path during the construction stage being fixed as the stress path during the use stage, making it difficult to achieve phased switching and optimization of the stress state, and making it difficult to balance the safety and flexibility during the construction stage with the overall stress rationality after the structure is formed.

[0005] Therefore, there is an urgent need for a prefabricated staircase concealed seismic connection node that can balance construction convenience and seismic performance, and achieve reasonable stress distribution at different stages. Summary of the Invention

[0006] Another objective of this invention is to provide a concealed seismic-resistant connection node for prefabricated staircases and its construction method, which can realize the active separation and orderly conversion of the force system between the assembly stage and the use stage, realize the orderly conversion of the force path, and form a concealed overall seismic-resistant connection node to ensure the continuity of structural force and ductility performance.

[0007] To achieve these objectives and other advantages of the present invention, a prefabricated staircase concealed seismic connection node is provided for connecting staircase components and main components into a whole, including shear reinforcement components and adjustment components disposed on the main components, and steel components disposed on the staircase components, wherein the steel components and the adjustment components are detachably connected, and the shear reinforcement components, steel components and adjustment components are formed by integrally casting concrete to form the connection node. The steel components are used to transfer the load of the stair components to the main components through the adjustment components during the assembly stage, and to transfer the load of the stair components to the concrete and shear reinforcement components after the concrete at the connection node reaches the design strength.

[0008] Preferably, the shear reinforcement assembly includes a plurality of shear stirrups spaced apart along the length of the main component. One end of each shear stirrup is embedded in the main component, and the other end extends out of the main component and is connected into a whole by a plurality of longitudinal reinforcing bars. Any longitudinal reinforcing bar is welded to the inner bottom surface of the plurality of shear stirrups.

[0009] Preferably, the adjustment assembly includes multiple support components spaced apart along the length of the main component and located below the first shear stirrup. Each support component includes a first load-bearing plate pre-embedded in the main component, a second load-bearing plate vertically arranged on the first load-bearing plate, a support plate welded between the bottom surfaces of the first load-bearing plate and the second load-bearing plate, the free end of the second load-bearing plate extending horizontally out of the main component, two guide plates symmetrically arranged on both sides of the top surface of the free end of the second load-bearing plate, and an adjustment bolt installed on the free end of the second load-bearing plate.

[0010] Preferably, the steel component includes multiple shear stirrups 2 embedded inside the stair component, the multiple shear stirrups 2 are welded to one side of the same steel plate, the other side of the steel plate extends out of the stair component and is welded with multiple stair support pads, the multiple stair support pads are respectively connected to the multiple supporting components.

[0011] Preferably, any stair support pad includes a support pad frame, which is a rectangular frame structure formed by welding multiple steel plates. The steel plate on one side of the support pad frame is welded to the steel plate, and the steel plate on the other side is clamped between two guide plates. The steel plate at the bottom of the support pad frame abuts against the top surface of the first adjusting bolt, and the installation height of the stair component is adjusted by the first adjusting bolt. The second load-bearing plate has threaded holes, and the steel plates at the top and bottom of the support pad frame have corresponding semi-circular through holes. The second adjusting bolt passes through the threaded holes and the semi-circular through holes to connect the stair support pad and the support assembly into a whole.

[0012] Preferably, the bottom of the steel plate located between the two guide plates is provided with a chamfered structure.

[0013] Preferably, steel components are welded to the sidewalls of the steel plate extending outside the staircase components.

[0014] A construction method for a concealed seismic-resistant connection node in a prefabricated staircase includes the following steps: S1. Precast main components: During the precasting stage of the main components, shear-resistant steel reinforcement components and supporting components are pre-embedded at the connection between the main components and the stair components. S2. Precast stair components: During the prefabrication stage of the stair components, shear stirrups and steel plates are pre-embedded at the connection between the stair components and the main components; after the stair components are prefabricated, stair support pads are welded onto the steel plates. S3. Install the main components. After the main components are installed in place, adjust the top surface of adjusting bolt one to the design elevation position according to the design elevation requirements of the stair components. S4. Hoist the stair components until the bottom surface of the stair support pad abuts against the top surface of the adjusting bolt one, and then adjust the adjusting bolt one again until the stair components are at the design elevation position; S5. After the stair components are adjusted to the design elevation, the stair support pads and support components are connected by adjusting bolt two, and the stair components and support components are temporarily connected. S6. Cast the reserved connection area between the main components and the stair components, so that the shear reinforcement components, steel components and adjustment components form an integral cast connection node; S7. Once the strength of the connection node reaches the design requirements, remove adjusting bolt one and adjusting bolt two, and release the temporary connection between the stair components and the supporting components. At this point, the construction of the concealed seismic connection node of the prefabricated staircase is completed.

[0015] The present invention has at least the following beneficial effects: 1. In the assembly stage, this invention forms a temporary support system by connecting steel components and adjusting components. After the cast-in-place connection nodes reach their design strength, the connection between the steel components and adjusting components gradually transfers the end loads of the stair components to the permanent seismic-resistant load-bearing system composed of shear-resistant steel reinforcement components and cast-in-place concrete. By constructing a dual-path structure in the nodes, which separates the temporary load-bearing system during the assembly stage from the permanent seismic-resistant load-bearing system during the service stage, the construction load and the design seismic-resistant load-bearing path are separated and orderly converted in time and space. This avoids the adverse effects of non-design conditions during the construction stage on the final seismic-resistant steel reinforcement system, thereby improving the safety and reliability of the nodes. This design enhances the structure's ability to maintain its function under seismic loads and its post-disaster repairability. When extreme forces such as earthquakes cause local damage or failure of cast-in-place connection nodes, the temporary load-bearing system formed during the original assembly stage can still continue to bear the basic load at the end of the staircase, forming a redundant load-bearing path. This ensures the structural integrity of the evacuation route and provides adjustable and reusable conditions for post-disaster repair, improving the structural system's toughness and recoverability. Furthermore, the node construction is hidden inside the main components, avoiding the impact of exposed corbels or cantilevered steel components on the building space and facade effect. It also reduces the need for later anti-corrosion and fireproofing maintenance, improving the overall durability and economy of the building.

[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0017] Figure 1 This is a structural schematic diagram of the concealed seismic-resistant connection node of the prefabricated staircase of the present invention; Figure 2This is a side sectional view of the concealed seismic-resistant connection node of the prefabricated staircase of the present invention. Figure 3 This is a schematic diagram of the connection structure of the shear reinforcement component, the support component, and the steel component of the present invention; Figure 4 This is a schematic diagram of the connection structure of the shear reinforcement component, the support component, and the steel component of the present invention; Figure 5 This is a schematic diagram of the connection structure of the shear reinforcement component, the support component, and the steel component of the present invention; Figure 6 This is a schematic diagram of the structure of the support component of the present invention; Figure 7 This is a schematic diagram of the installation structure of the shear reinforcement assembly of the present invention; Figure 8 This is a schematic diagram of the installation structure of the steel component of the present invention; Figure 9 This is a schematic diagram of the installation structure of the stair support pad and steel components of the present invention; Figure 10 This is a schematic diagram of the structure of the stair support pad of the present invention; Figure 11 This is a schematic diagram of the steel component of the present invention; Figure 12 This is a schematic diagram of the assembly structure of the support component and the stair support pad of the present invention; Figure 13 This is a structural schematic diagram of the cast-in-place stage of the present invention; Figure 14 This is a schematic diagram of the structure after the completion of the construction of this invention; Explanation of reference numerals in the instruction manual: 1. Staircase components; 2. Main components; 3. Shear reinforcement components; 301. Shear stirrup one; 302. Longitudinal reinforcing bars; 4. Support components; 401. Load-bearing plate one; 402. Load-bearing plate two; 403. Support plate; 404. Guide plate; 405. Adjusting bolt one; 406. Threaded hole; 5. Steel components; 501. Shear stirrup two; 502. Steel plate; 6. Staircase support pad; 601. Steel plate piece; 602. Semi-waisted through hole; 603. Chamfered structure; 604. Steel component; 605. Adjusting bolt two; 7. Connection node. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0019] It should be noted that in the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Example

[0020] In prefabricated staircase projects, the stress requirements of staircase connection nodes differ between the construction and normal service phases. During construction, the focus is on positioning, leveling, and temporary stability, with loads primarily consisting of hoisting loads and construction disturbances. However, the service phase must meet the requirements of long-term vertical loads and repeated stress under seismic action. If the loads during construction are directly borne by the final seismic-resistant steel reinforcement system, unfavorable stress states may arise before the connection nodes have fully formed constraints, affecting the structure's ductility. Furthermore, if there is a lack of clear transition design between temporary support structures and permanent connection systems, a smooth transition of the stress path cannot be guaranteed, impacting the stability of the connection nodes during construction and their seismic performance after completion. Therefore, it is necessary to design staircase connection nodes in stages and construct a controllable stress transition mechanism. Additionally, existing corbel structures often require complex cantilevered or additional structures during the prefabrication stage, increasing mold complexity and placing higher demands on reinforcement arrangement, demolding, and transportation, which is detrimental to the large-scale, standardized production of prefabricated components.

[0021] To solve the above problems, such as Figure 1-12 As shown, this embodiment provides a concealed seismic-resistant connection node for prefabricated stairs that enables an orderly transfer of force paths between the assembly construction stage and the normal use stage of the structure. It is used to connect the stair component 1 and the main component 2 into a whole, as shown below. Figure 1-3 As shown, it includes a shear reinforcement assembly 3 and an adjustment assembly set on the main component 2, and a steel assembly 5 set on the stair component 1. The steel assembly 5 and the adjustment assembly are detachably connected. The shear reinforcement assembly 3, the steel assembly 5 and the adjustment assembly are connected to a connection node 7 by integral concrete casting. Steel component 5 is used during the assembly stage to transfer the load of stair component 1 to the main component 2 via an adjusting component. After the concrete at connection node 7 reaches its design strength, it transfers the load of stair component 1 to the concrete and shear reinforcement component 3. Specifically: Shear reinforcement assembly 3 is a seismic-resistant reinforcing steel system, such as... Figure 4 , Figure 5 , Figure 7As shown, it includes multiple shear stirrups 301 spaced apart along the length of the main component 2. One end of each shear stirrup 301 is embedded in the main component 2, and the other end extends out of the outside of the main component and is connected into a whole by multiple longitudinal reinforcing bars 302. Any longitudinal reinforcing bar 302 is welded to the inner bottom surface of the multiple shear stirrups 301.

[0022] like Figure 5 , Figure 6 As shown, the adjustment assembly includes multiple support components 4 spaced apart along the length of the main component 2 and located below the shear stirrups 301. The support components 4 are used to adjust the elevation of the stair component 1 and provide temporary support during the assembly stage to form an independent force path during the construction stage. The support components 4 include a load-bearing plate 401 pre-embedded in the main component 2, a load-bearing plate 402 vertically arranged on the load-bearing plate 401, a support plate 403 welded between the bottom surfaces of the load-bearing plate 401 and the load-bearing plate 402, the free end of the load-bearing plate 402 extending horizontally out of the main component 2, two guide plates 404 symmetrically arranged on both sides of the top surface of the free end of the load-bearing plate 402, and an adjustment bolt 405 installed on the free end of the load-bearing plate 402 by high-strength bolts. The support components 4 can be installed between two adjacent shear stirrups 301 at corresponding positions to facilitate the installation and positioning of the support components 4.

[0023] like Figure 5 , Figure 8 , Figure 9 As shown, the steel component 5 includes multiple shear stirrups 501 pre-embedded inside the stair component 1. These shear stirrups 501 are welded to one side of the same steel plate 502. The other side of the steel plate 502 extends outward from the stair component 1 and is welded with multiple stair support pads 6. These stair support pads 6 are respectively connected to multiple supporting components 4. Figure 5 , Figure 10 As shown, any stair support pad 6 includes a support pad frame, which is a rectangular frame structure formed by welding multiple steel plates 601. One side of the support pad frame has a steel plate 601 welded to a steel plate 502, while the other side has a steel plate 601 secured between two guide plates 404. The bottom of the steel plate 601 has a chamfered structure 603, which reduces stress concentration during assembly and improves placement smoothness. The steel plate 601 at the bottom of the support pad frame abuts against the top surface of an adjusting bolt 405. The installation elevation of the stair component 1 is adjusted by the adjusting bolt 405. During assembly, the stair support pad 6 is positioned between two shear reinforcement bars 301 at corresponding positions. The steel plate 601 at the bottom of the support pad frame is positioned above the longitudinal reinforcing bars 302 to prevent the longitudinal reinforcing bars 302 and the shear reinforcement bars 301 from obstructing the connection and installation of the stair support pad and the supporting component 4. Figure 6 , Figure 10 , Figure 12As shown, the load-bearing plate 402 has threaded holes 406, and the steel plates 601 at the top and bottom of the support frame have corresponding semi-circular through holes 602. Adjusting bolts 605 pass through the threaded holes 406 and semi-circular through holes 602 to connect the stair support pad 6 and the support assembly 4 into a whole. The steel assembly 5 and the adjusting assembly are detachably connected by bolting. The semi-circular through holes 602 are used to adjust assembly errors and release local constraint stress. Steel components 604 are also welded to the side wall of the steel plate 502 extending outside the stair component 1, such as... Figure 11 As shown, steel component 604 is a rectangular frame structure formed by welding multiple steel plates identical to the support frame.

[0024] During the assembly phase, after the stair component 1 is hoisted into place, the steel component 5 is connected to the adjusting component to form a temporary support system. The end load of the stair component 1 is first transferred to the adjusting component through the steel component 5, forming an independent temporary force path. This allows the temporary support system to bear the vertical loads and disturbance loads generated during the construction phase, and to separate it from the final seismic-resistant steel reinforcement system. After the cast-in-place connection node reaches its design strength, the connection between the steel component 5 and the adjusting component is released by adjusting bolt 405 and adjusting bolt 605, allowing the end load of the stair component 1 to be gradually transferred to the permanent seismic-resistant force system composed of the shear-resistant steel reinforcement component 3 and the cast-in-place concrete. This invention achieves the active separation and orderly conversion of the force system between the assembly phase and the service phase by constructing a "controllable dual force path node," realizing the orderly conversion from the temporary force path in the assembly phase to the seismic-resistant force path in the service phase. At the same time, it forms a hidden integral seismic-resistant connection node, ensuring the continuity and ductility of the structure. In the event of an earthquake, if the cast-in-place connection node is damaged and fails, the temporary support system of the original assembly stage can still bear the load at the end of the staircase, ensuring that the escape route is unobstructed. After the disaster, the staircase elevation can be adjusted and cast-in-place can be carried out again, and the node can still be used. At this time, the original temporary support system is converted into a load-bearing component to continue to bear the basic load at the end of the staircase, forming a redundant load path. This provides adjustable and reusable conditions for post-disaster repair, improving the seismic toughness and recoverability of the node.

[0025] The construction method for concealed seismic connection nodes in prefabricated staircases, as described above, includes the following steps: S1. Precast main component 2. In this embodiment, the main structure is a precast wall panel. During the prefabrication stage of the main component 2, shear reinforcement assembly 3 and support assembly 4 are pre-embedded at the corresponding positions where it connects with the stair component 1. The shear reinforcement assembly 3 includes longitudinal reinforcing bars 302 and shear stirrups 301. The longitudinal reinforcing bars 302 can be integrated during the prefabrication of the wall panel to ensure the anchorage length and stress continuity of the reinforcing bars, and to avoid the need for supplementary or welding operations in the later stage under the limited space of the stairwell, thereby improving the feasibility of construction and the reliability of the structure, without increasing the complexity of the wall panel mold structure. The support assembly 4 is equipped with an adjustable adjusting bolt 405 so that the support assembly 4 has an adjustment function. The adjusting bolt 405 is a high-strength bolt. The support assembly 4 is used to adjust the elevation of the stair component 1 and provide temporary support during the assembly stage to form an independent stress path during the construction stage.

[0026] S2. Precast stair component 1: During the prefabrication stage of stair component 1, shear stirrup 2 501 and steel plate 502 are pre-embedded at the connection between stair component 1 and main component 2. Shear stirrup 2 501 and steel plate 502 are used to form a structural connection interface with the support component 4 in the main component 2 and the subsequent cast-in-place connection node, and serve as key force transmission components for staged force conversion. The pre-embedding method during the prefabrication stage ensures its anchorage reliability and force continuity, while not increasing the complexity of the stair mold structure. After the stair component 1 is prefabricated, stair support pad 6 and steel component 604 are welded onto steel plate 502. The stair support pad 6 serves as a contact force transmission component in the temporary force path during the assembly stage. It is used to form a rigid support contact interface with the support component 4 in the main component 2, so as to stably transfer the vertical load and local bending moment generated at the end of the staircase to the support component 4. The steel component 604 is used to further improve the strength of the cast connection node.

[0027] S3. On the construction site, the main component 2 is hoisted and positioned to ensure that the precast wall panel is accurately installed in the design position and forms a stable support state. According to the design elevation requirements of the stair component 1, the top surface of the adjusting bolt 405 is initially adjusted to the design elevation position. Specifically, the adjusting bolt 405 is rotated so that its top support surface is close to the design control elevation, providing an initial support benchmark for the subsequent installation of the stair component 1. The pre-adjustment process is used to establish a temporary bearing interface in the assembly stage, so that after the stair component 1 is installed, it can achieve fine elevation correction through the support component 4 and form a controllable force path in the construction stage.

[0028] S4. The stair component 1 is hoisted so that the stair support pad 6 at its end is in contact with the support component 4. The steel plate 601 with the chamfered structure 603 on the stair support pad 6 forms a contact guide interface with the two guide plates 404 on the support component 4 during the lowering process, thereby forming a self-guiding positioning relationship. This guides the stair component 1 to move along the predetermined direction to the design position, corrects local deviations during hoisting, reduces manual intervention, reduces stress concentration during assembly, and improves the smoothness of positioning, achieving fast and stable positioning and reducing the risk of component damage caused by hard collisions. When the steel plate 601 located on the bottom surface of the stair support pad 6 contacts the top support surface of the adjusting bolt 405, the stair component 1 completes its initial positioning and forms a stable temporary support state. The adjusting bolt 405 is then rotated again until the stair component 1 is at the design elevation, ensuring that the elevation, levelness, and installation position of the stair component 1 meet the design accuracy requirements. At this stage, no permanent connection nodes have been formed between the components. The structural load forms an independent temporary force system through the adjusting assembly. Its force path is: end load of stair component 1 → stair support pad 6 → adjusting assembly → main component 2. This temporary force system bears the construction stage load before the formation of the cast-in-place node and is independent of the subsequent permanent seismic force system, thereby achieving staged force separation and controllable conversion.

[0029] S5. After adjusting the stair component 1 to the design elevation, screw in the adjusting bolt 605 into the threaded hole 406 and the semi-circular through hole 602, and equip it with a shim. Connect the stair support pad 6 and the support component 4 to achieve a temporary locking connection between the stair component 1 and the main component 2, so that the two form an integral temporary constraint system during the assembly stage. This temporary connection node can constrain and distribute the horizontal construction dynamic load and possible eccentric effects on the basis of the support component 4 bearing the vertical load, thereby improving the overall stability during the safety stage and keeping the force path clear and controllable. Through this temporary locking measure, the main component 2 and the stair component 1 can form a stable force unit before the cast-in-place node is formed. At the same time, this structural form provides the construction conditions for permanent connection after the main structure of the building has basically settled, realizing the phased establishment of the temporary force system and the final seismic force system in the time dimension. The semi-circular through hole 602 is used to adjust assembly errors and release local constraint stress.

[0030] During the construction phase, adverse factors such as vibration loads, impact loads, and eccentricity may exist, causing disturbance to the already positioned stair component 1. However, due to the synergistic effect of adjusting bolt 405, adjusting bolt 605, and the self-weight of stair component 1, a multi-faceted contact interlocking combination structure is formed between the supporting component 4 and the stair support pad 6, thus forming a temporary integral unit with spatial constraint characteristics. This combination structure can effectively resist the displacement and rotation caused by construction dynamic loads and eccentric loads, ensuring structural stability during the assembly phase. In this state, the temporary force path is: end load of stair component 1 → stair support pad 6, supporting component 4 → main component 2. Even if adjusting bolt 405 and adjusting bolt 605 fail under sudden strong impact or abnormal load, the supporting component 4 and the stair support pad 6 will still form a three-dimensional spatial constraint system through structural limiting, as detailed below. Figure 12 As shown: In the Z-axis direction, the upper part is restricted by the self-weight of the stair component 1, and the lower part is supported and limited by the load-bearing plate 401 on the stair support pad 6; in the Y-axis direction, the steel plate 601 located between the two guide plates 404 is laterally clamped and restricted by the two guide plates 404; in the X-axis direction, the steel plate 601 located between the two guide plates 404 is laterally constrained by the structural boundary of the main component 2 and the adjusting bolt 605. Even if the adjusting bolt 605 fails, the load-bearing plate 401 can still provide necessary displacement for it, thus forming a multiple structural redundancy mechanism, so that the main component 2 and the stair component 1 remain under control under extreme working conditions, thereby ensuring structural safety and the continuity of the staircase as an evacuation route.

[0031] S6, such as Figure 13 As shown, cast-in-place concrete or high-strength grouting is carried out in the reserved connection area between the main component 2 and the stair component 1, so that the shear reinforcement component 3, the steel component 5 and the adjustment component form an integral cast-in-place connection node 7. Through vibration compaction and standardized curing, the connection node 7 reaches the design strength requirements. After the formation of this cast-in-place connection node 7, a continuous reinforcement anchorage and concrete integral force system is established between the stair component 1 and the main component 2, providing a structural foundation for the subsequent conversion of the temporary force path to the permanent seismic force path. This connection node not only undertakes the function of vertical load transfer, but also forms a structural core area that works in coordination with shear, bending and seismic resistance.

[0032] S7. Once the strength of the connection node meets the design requirements, such as Figure 14As shown, by manually and actively unscrewing adjusting bolts 405 and 605, the supporting component 4 and the stair support pad 6 are released from their stress-bearing contact state, thus terminating the temporary connection between the stair component 1 and the supporting component 4 and dismantling the temporary stress system formed during the assembly stage. This releases the stress between the supporting component 4 and the support pad 6. After this stress release, the structure enters the forming and service stage, and the load transfer path changes. The stress path is as follows: end load and displacement control of stair component 1 → stair support pad 6, steel component 604 → cast-in-place connection node → shear reinforcement component 3 → main component 2. This process, through active yielding structural design, achieves a controllable conversion from a temporary stress system to a permanent seismic-resistant stress system, making the stress paths of the construction stage and the service stage independent of each other in the time dimension, forming a continuous and reliable overall stress system after the structure is formed.

[0033] After the bolts are removed, the construction of the concealed seismic connection node of the prefabricated staircase is completed. The main component 2 and the staircase component 1 form a continuous and stable overall load-bearing structure, and the structure enters the normal use state.

[0034] Under rare earthquakes or extreme working conditions, through differentiated design of component stiffness and load-bearing capacity, the cast-in-place connection area composed of shear stirrups and longitudinal reinforcing bars is made a controllable ductile energy-dissipating component that preferentially enters the deformation stage. Meanwhile, the supporting components, stair supports, and steel components, due to their high stiffness and strength design, remain basically intact in the overall structure. Through the above-mentioned graded design of structural performance, the connection nodes form a "controllable damage, main body preservation" failure mode under strong earthquake action. During post-earthquake repair, it is only necessary to reset the stair components and clean and recast the cast-in-place connection node areas that have undergone plastic deformation or damage to restore the overall structural performance. During the repair stage, the shear stirrups and longitudinal reinforcing bars are removed from the main load-bearing system due to deformation, and the combined structure of the supporting components, stair supports, and steel components assumes the load-bearing function under the service conditions.

[0035] This invention, through the pre-embedded arrangement of various connecting components, node structural design, temporary stress control, and final overall stress formation, classifies and controls the stress state of staircase connection nodes at different stages. By constructing a hidden seismic-resistant connection node system, an independent temporary stress path is formed during the assembly stage to withstand hoisting and construction disturbance loads. After the nodes are cast-in-place or the connection structure reaches the design strength, the stress is converted from the temporary support system to the permanent seismic-resistant stress system in a controllable manner. This achieves the separation design and controllable conversion of the stress path between the assembly stage and the service stage, enabling the structure to enter a continuous and reliable permanent seismic-resistant stress state. The stress path after the structure is formed meets the seismic design requirements. Under strong earthquakes, a controllable ductile failure mode is formed through performance-graded design, preserving key steel components. This approach enables rapid post-earthquake repair and functional restoration, ultimately achieving synergistic optimization of safety and stability during the construction phase and seismic performance during the usage phase. It enhances the overall reliability of prefabricated staircase joints, improves their stability during construction, and enhances their seismic performance after completion. Without significantly increasing the structural complexity and production difficulty of components, it addresses the issues of mixed force paths, lack of phased control, and the difficulty in balancing seismic performance and construction convenience in prefabricated staircase connection joints during construction and usage phases. It not only solves the technical challenges of installation accuracy, force conversion, and seismic performance in prefabricated staircases but also achieves an orderly connection of the force systems during construction and usage phases in a temporal dimension, forming a prefabricated connection method and system with clear structural paths, distinct phases, safety redundancy, and recoverability.

[0036] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A concealed seismic-resistant connection node for prefabricated staircases, used to connect staircase components and main body components into a whole, characterized in that, It includes shear reinforcement components and adjustment components installed on the main components, and steel components installed on the stair components. The steel components and the adjustment components are detachably connected. The shear reinforcement components, steel components and adjustment components are connected by integral concrete casting to form a connection node. The steel components are used to transfer the load of the stair components to the main components through the adjustment components during the assembly stage, and to transfer the load of the stair components to the concrete and shear reinforcement components after the concrete at the connection node reaches the design strength.

2. The prefabricated staircase concealed seismic connection node as described in claim 1, characterized in that, The shear reinforcement assembly includes multiple shear stirrups spaced apart along the length of the main component. One end of each shear stirrup is embedded in the main component, and the other end extends out of the main component and is connected into a whole by multiple longitudinal reinforcing bars. Any longitudinal reinforcing bar is welded to the inner bottom surface of the multiple shear stirrups.

3. The concealed seismic-resistant connection node for prefabricated staircases as described in claim 2, characterized in that, The adjustment assembly includes multiple support components spaced apart along the length of the main component and located below the first shear stirrup. Each support component includes a first load-bearing plate embedded in the main component, a second load-bearing plate vertically mounted on the first load-bearing plate, a support plate welded between the bottom surfaces of the first and second load-bearing plates, the free end of the second load-bearing plate extending horizontally out of the main component, two guide plates symmetrically arranged on both sides of the top surface of the free end of the second load-bearing plate, and an adjustment bolt installed on the free end of the second load-bearing plate.

4. The concealed seismic-resistant connection node for prefabricated staircases as described in claim 3, characterized in that, The steel component includes multiple shear stirrups embedded inside the stair component. The multiple shear stirrups are welded to one side of the same steel plate. The other side of the steel plate extends out of the stair component and is welded with multiple stair support pads. The multiple stair support pads are respectively connected to the multiple supporting components.

5. The prefabricated staircase concealed seismic-resistant connection node as described in claim 4, characterized in that, Each stair support pad includes a support pad frame, which is a rectangular frame structure formed by welding multiple steel plates. The steel plate on one side of the support pad frame is welded to the steel plate, and the steel plate on the other side is clamped between two guide plates. The steel plate at the bottom of the support pad frame abuts against the top surface of the first adjusting bolt, and the installation elevation of the stair component is adjusted by the first adjusting bolt. The second load-bearing plate has threaded holes, and the steel plates at the top and bottom of the support pad frame have corresponding semi-circular through holes. The second adjusting bolt passes through the threaded holes and the semi-circular through holes to connect the stair support pad and the support assembly into a whole.

6. The concealed seismic-resistant connection node for prefabricated staircases as described in claim 5, characterized in that, The bottom of the steel plate located between the two guide plates has a chamfered structure.

7. The concealed seismic-resistant connection node for prefabricated staircases as described in claim 4, characterized in that, The steel plate extends outward from the side wall of the staircase component, where steel components are also welded.

8. A construction method for a concealed seismic-resistant connection node in a prefabricated staircase as described in claim 5, characterized in that, Includes the following steps: S1. Precast main components: During the precasting stage of the main components, shear-resistant steel reinforcement components and supporting components are pre-embedded at the connection between the main components and the stair components. S2. Precast stair components: During the prefabrication stage of the stair components, shear stirrups and steel plates are pre-embedded at the connection between the stair components and the main components; after the stair components are prefabricated, stair support pads are welded onto the steel plates. S3. Install the main components. After the main components are installed in place, adjust the top surface of adjusting bolt one to the design elevation position according to the design elevation requirements of the stair components. S4. Hoist the stair components until the bottom surface of the stair support pad abuts against the top surface of the adjusting bolt one, and then adjust the adjusting bolt one again until the stair components are at the design elevation position; S5. After the stair components are adjusted to the design elevation, the stair support pads and support components are connected by adjusting bolt two, and the stair components and support components are temporarily connected. S6. Cast the reserved connection area between the main components and the stair components, so that the shear reinforcement components, steel components and adjustment components form an integral cast connection node; S7. Once the strength of the connection node reaches the design requirements, remove adjusting bolt one and adjusting bolt two, and release the temporary connection between the stair components and the supporting components. At this point, the construction of the concealed seismic connection node of the prefabricated staircase is completed.

Images