Prefabricated stairway and method of construction thereof

Abstract

This invention discloses a prefabricated staircase and its construction method, relating to the field of prefabricated building construction technology. By setting up the staircase body and two anchoring structures, under normal use, the anchoring structures provide sufficient vertical bearing capacity and horizontal shear resistance, ensuring the overall stability of the staircase. In the event of sudden disasters such as earthquakes, due to the presence of through-type anchor bodies within the anchor holes, when the stair slab participates in resisting lateral forces in the main structure, the shear force is mainly distributed to the load-bearing beam through the anchor bodies in the anchor hole area, rather than concentrated at the single lap interface between the stair slab and the load-bearing beam. This effectively avoids concentrated shear failure caused by the short column effect at the stair slab ends due to abrupt changes in stiffness, reducing the risk of brittle shear failure of the stair slab, thereby protecting the prefabricated staircase components from severe damage. The staircase is less prone to overall collapse or severe displacement, which helps maintain the relative unobstructed escape route during earthquakes and increases the possibility of safe evacuation.

Description

Technical Field

[0001] This invention relates to the field of prefabricated construction technology, and in particular to a prefabricated staircase and its construction method. Background Technology

[0002] In current technology, when installing prefabricated stairs, grouting materials are usually used to fix the prefabricated stairs to the load-bearing beams. Although this method can fix the prefabricated stairs to the load-bearing beams, when a sudden disaster such as an earthquake occurs, the prefabricated stairs will participate in the lateral force resistance of the main structure, generating a short column effect, which will cause the stair slabs to undergo shear failure. This not only damages the components, but may also block the escape route and prevent people from evacuating safely. Summary of the Invention

[0003] The main objective of this invention is to propose a prefabricated staircase and its construction method, aiming to solve the technical problem that in the existing technology, when installing prefabricated staircases, grouting materials are usually used to directly fix the prefabricated staircases to the load-bearing beams. Although this method can fix the prefabricated staircases to the load-bearing beams, when sudden disasters such as earthquakes occur, the prefabricated staircases will participate in the lateral force resistance of the main structure, generating a short column effect, which will cause the stair slabs to undergo shear failure. This not only damages the components, but may also block the escape route and hinder the safe evacuation of personnel.

[0004] To achieve the above objectives, in a first aspect, the present invention proposes a prefabricated staircase, wherein the high end and the low end of the prefabricated staircase are respectively erected on load-bearing beams on two adjacent floor slabs, and anchoring positions are provided on both load-bearing beams. The prefabricated staircase includes: The ladder body is a precast reinforced concrete structure. Anchoring holes extending vertically through the ladder body are formed at both its high and low ends. Both the high and low ends of the ladder body can overlap with corresponding anchoring positions, forming an anchoring filling space between them. Two anchoring structures are provided, which can enter and fill the anchoring filling space and the anchoring hole to anchor the ladder body to the corresponding load-bearing beam.

[0005] In one embodiment, the anchoring filling space includes interconnected horizontal and vertical regions. A plurality of vertically arranged guide members are pre-embedded at the anchoring position. The guide members are arranged in the horizontal region. The number of anchoring holes is the same as the number of guide members, and they are inserted and fitted one-to-one.

[0006] In one embodiment, the anchoring structure includes: A first anchoring component, capable of filling the anchoring filling space, thereby anchoring the ladder body to the corresponding load-bearing beam; and... The second anchoring component can be filled into the anchoring hole to fix the ladder body to the load-bearing beam.

[0007] In one embodiment, the first anchoring component includes: A calibration pad is placed between the bottom surface of the ladder body and the load-bearing beam. The calibration pad is located in the horizontal area and avoids the guide member. A leveling layer, said leveling layer filling the horizontal area to fix the calibration pad and the guide member; and A buffer component, which fills the vertical area and whose bottom is connected to the leveling layer.

[0008] In one embodiment, the buffer assembly includes a polystyrene board, a PE rod, and an adhesive layer, which are filled sequentially from bottom to top within the vertical region.

[0009] In one embodiment, the adhesive layer is located on top of the PE rod, and the top surface of the adhesive layer is at the same elevation as the top surface of the ladder body.

[0010] In one embodiment, the leveling layer is made of cement mortar with a strength grade of A, where A ≥ M15.

[0011] In one embodiment, the anchoring holes are arranged in a gradually decreasing vertical direction from top to bottom.

[0012] In one embodiment, the second anchoring component includes: Grouting material, which is filled into the anchoring hole to connect the guide member and the ladder body as a single unit; and, A mortar sealing layer is provided, which fills the anchor hole and is located on top of the grouting material, and the top elevation of the mortar sealing layer is consistent with the top elevation of the ladder body.

[0013] Based on the same technical concept, in a second aspect, the present invention also proposes a construction method for a prefabricated staircase, used for constructing the prefabricated staircase described in the first aspect, the construction method comprising the following steps: In the pre-designed construction area, reinforced concrete is poured in place to form two load-bearing beams that are spaced apart vertically; wherein, each load-bearing beam has an anchorage position, and the two anchorage positions are opposite to each other and staggered vertically. After the load-bearing beams reach the preset strength, the ladder body is hoisted and installed at the anchoring positions of the two load-bearing beams; wherein, an anchoring filling gap is formed between the high end and the low end of the ladder body and the corresponding anchoring position. Anchoring structures are constructed within the two anchoring gaps to complete the installation of the ladder body.

[0014] The technical solution of this invention, through the setting of a ladder body and two anchoring structures, achieves an anchoring connection between the ladder body and the load-bearing beam by setting vertically penetrating anchoring holes at the high and low ends of the ladder body, and simultaneously filling the anchoring space formed by the anchoring holes and the overlap using the anchoring structures. Under normal use, the anchoring structures provide sufficient vertical bearing capacity and horizontal shear resistance, ensuring the overall stability of the staircase. In the event of sudden disasters such as earthquakes, due to the presence of through anchor bodies in the anchoring holes, when the ladder slab participates in resisting lateral forces of the main structure, the shear force is mainly distributed to the load-bearing beam through the anchor bodies in the anchoring hole area, rather than concentrated at the single overlap interface between the ladder slab and the load-bearing beam. This effectively avoids concentrated shear failure caused by the short column effect at the end of the ladder slab due to abrupt changes in stiffness, reducing the risk of brittle shear failure of the ladder slab, thereby protecting the prefabricated staircase components from severe damage. At the same time, since shear failure at the end of the ladder slab is effectively suppressed, the staircase is less likely to collapse or shift severely, which helps to maintain the relative unobstructed escape route during earthquakes and increases the possibility of safe evacuation of personnel. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a structural schematic diagram of the prefabricated staircase provided by the present invention; Figure 2 for Figure 1 An enlarged structural diagram of part A in the example; Figure 3 This is a flowchart illustrating a construction method exemplified by the present invention.

[0017] Figure label: 100. Load-bearing beam; 200. Ladder body; 210. Anchor hole; 300. Anchoring structure; 220. Horizontal area; 230. Vertical area; 400. Guide component; 310. First anchoring component; 320. Second anchoring component; 311. Adjustment pad; 312. Leveling layer; 313. Buffer assembly; 314. Polystyrene board; 315. PE rod; 316. Adhesive layer; 321. Grouting material; 322. Mortar sealing layer.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] In current technology, when installing prefabricated stairs, grouting materials are usually used to fix the prefabricated stairs to the load-bearing beams. Although this method can fix the prefabricated stairs to the load-bearing beams, when a sudden disaster such as an earthquake occurs, the prefabricated stairs will participate in the lateral force resistance of the main structure, generating a short column effect, which will cause the stair slabs to undergo shear failure. This not only damages the components, but may also block the escape route and prevent people from evacuating safely.

[0023] This invention proposes a prefabricated staircase and its construction method.

[0024] Please see Figures 1 to 3 For ease of understanding, this type of prefabricated staircase has its high and low ends mounted on load-bearing beams 100 on two adjacent floor slabs, with anchoring positions provided on both load-bearing beams 100. Precast stairs include: The ladder body 200 is a precast reinforced concrete structure. Anchor holes 210 are formed at both the high and low ends of the ladder body 200, penetrating vertically. Both the high and low ends of the ladder body 200 can overlap with corresponding anchoring positions, forming an anchoring filling space between them. Two anchoring structures 300 are provided, which can enter and fill the anchoring filling space and the anchoring hole 210, so that the ladder body 200 is anchored to the corresponding load-bearing beam 100.

[0025] Specifically, the high end of the prefabricated staircase is erected on the load-bearing beam 100 of the upper floor slab, and the low end of the prefabricated staircase is erected on the load-bearing beam 100 of the lower floor slab. Anchorage positions are pre-set on the two load-bearing beams 100, and the anchorage positions can be in the form of embedded steel plates, steel components or reserved anchorage grooves, etc.

[0026] The ladder body 200 is integrally cast using precast reinforced concrete, with processes such as rebar tying, formwork erection, concrete pouring, and curing completed in the factory. Anchor holes 210, extending vertically through the entire thickness of the ladder slab, are formed at both the high and low ends of the ladder body 200. The cross-sectional shape of these anchor holes 210 can be circular, rectangular, or polygonal, with the diameter and depth determined based on stress calculations. They typically penetrate the entire thickness of the ladder slab to ensure sufficient penetration of the anchoring material. After the ladder body 200 is formed, it is transported to the site. During hoisting and positioning, the high end of the ladder body 200 overlaps with the corresponding anchoring position of the upper load-bearing beam 100, and the low end overlaps with the corresponding anchoring position of the lower load-bearing beam 100. At this time, anchoring filling spaces with a certain height are naturally formed between the high bottom surface of the ladder body 200 and the upper surface of the upper anchoring position, and between the low bottom surface of the ladder body 200 and the upper surface of the lower anchoring position. The thickness of the space is generally controlled within the range of 10mm to 50mm, depending on the design gap and construction precision.

[0027] Subsequently, two anchoring structures 300 are constructed at the corresponding anchoring areas at the high and low ends of the ladder body 200, respectively. The specific construction process is as follows: First, the inner walls of the anchoring holes 210 and the contact surfaces of the anchoring filling spaces are cleaned to ensure there is no floating dust, oil, or loose particles. Then, high-pressure air blowing or vacuuming is used to remove accumulated water and debris. Next, after the anchoring material is prepared, it is poured into the anchoring holes 210 on the upper or lower surface of the ladder body 200, allowing the anchoring material to gradually fill the entire anchoring hole 210 under gravity and with appropriate vibration, continuing to overflow and fill the anchoring filling spaces at the high or low ends until the anchoring filling spaces are completely filled and the surface is slightly higher than the reference surface of the anchoring position of the load-bearing beam 100. After the anchoring material has initially set, the overflow portion can be smoothed and finished as needed.

[0028] After hardening, the anchoring structure 300 achieves a firm engagement with the ladder body 200 through the through-hole anchoring body formed in the anchoring hole 210. On the other hand, the anchoring body filled in the anchoring filling space forms a large area of ​​bonding and compression connection with the anchoring position of the load-bearing beam 100, thereby making the ladder body 200 and the upper and lower load-bearing beams 100 form an integral force-bearing system.

[0029] In this embodiment, vertically penetrating anchor holes 210 are provided at the high and low ends of the stair body 200, and the anchoring structure 300 simultaneously fills the anchor holes 210 and the anchoring filling space formed by the overlap, thereby achieving the anchoring connection between the stair body 200 and the load-bearing beam 100. Under normal use, the anchoring structure 300 provides sufficient vertical bearing capacity and horizontal shear resistance to ensure the overall stability of the staircase. In the event of sudden disasters such as earthquakes, due to the presence of through anchor bodies within the anchor holes 210, when the stair slab participates in resisting lateral forces in the main structure, the shear force is mainly dispersed and transmitted to the load-bearing beam 100 through the anchor bodies in the area of ​​the anchor holes 210, rather than being concentrated on the single overlap interface between the stair slab and the load-bearing beam 100. This effectively avoids concentrated shear failure caused by the short column effect at the end of the stair slab due to abrupt changes in stiffness, reduces the risk of brittle shear failure of the stair slab, and thus protects the prefabricated staircase components themselves from severe damage. At the same time, because shear failure at the ends of the stair slabs is effectively suppressed, the staircase is less likely to collapse as a whole or shift severely, which helps to keep the escape route relatively unobstructed during an earthquake and increases the possibility of safe evacuation of people.

[0030] In one embodiment, the anchoring filling space includes a horizontal region 220 and a vertical region 230 that are interconnected. A plurality of guide members 400 arranged vertically are pre-embedded at the anchoring position. The guide members 400 are arranged in the horizontal region 220. The number of anchoring holes 210 is the same as that of the guide members 400 and they are inserted and matched one by one.

[0031] Specifically, the horizontal region 220 is mainly located in the planar gap formed between the top or bottom surface (or top surface) of the ladder body 200 and the top surface (or bottom surface) of the anchorage position of the load-bearing beam 100, and its thickness is usually controlled in the range of 20mm to 50mm; the vertical region 230 is mainly composed of the small vertical gap that may exist between the side of the end of the ladder body 200 and the lateral limiting surface of the anchorage position of the load-bearing beam 100. The vertical region 230 is generally small in height but is connected to the horizontal region 220, so that the entire anchorage filling space forms an integral and connected cavity, which facilitates the uniform flow and filling of the anchorage material from bottom to top or from one side to multiple directions during the grouting process.

[0032] Multiple vertically extending guide members 400 are pre-embedded at the anchorage positions of the load-bearing beam 100. These guide members 400 can be made of various forms such as reinforcing bars, threaded steel bars, short steel sections, or precast concrete pins, and are typically pre-embedded during the casting of the load-bearing beam 100 or the installation of the anchorage components. The guide members 400 are vertically positioned, with their lower (or upper) end anchored in the concrete inside the load-bearing beam 100, and their upper (or lower) end extending beyond the top surface of the anchorage position. The extension length is generally 1 / 3 to 2 / 3 of the total length of the guide member 400, depending on the height of the anchorage filling space and the guiding requirements. The extended portion of the guide member 400 is located within the horizontal area 220, and its position is precisely aligned with the anchorage hole 210 at the corresponding end of the ladder body 200.

[0033] During the prefabrication stage, vertical through anchoring holes 210, corresponding in number and position to the guide members 400, are pre-drilled at both the high and low ends of the ladder body 200 according to the design drawings. The diameter of the anchoring holes 210 is typically 10mm to 30mm larger than the outer diameter of the guide members 400 to form an annular gap, facilitating the wrapping and gripping of subsequent anchoring materials. During hoisting and positioning, the high or low end of the ladder body 200 is slowly lowered, allowing each anchoring hole 210 to be accurately fitted into its corresponding guide member 400, until the ladder body 200 is fully anchored to the load-bearing beam 100. At this point, the guide member 400 penetrates the entire anchoring hole 210 and extends upward (or downward) by a certain length within the horizontal area 220, forming preliminary positioning and guiding constraints on the ends of the ladder body 200.

[0034] Following this, the anchoring material is poured in. Before pouring, the upper opening and surrounding area of ​​the anchoring hole 210 are cleaned. Then, high-flowability anchoring material is slowly poured into the upper (or lower, depending on the orientation) end of the anchoring hole 210. Under gravity and appropriate vibration, the material first flows downwards (or upwards) along the anchoring hole 210, wrapping the outer surface of the guide member 400 and filling the annular gap between the hole wall and the guide member 400. After the anchoring material fills the anchoring hole 210, it continues to overflow upwards (or downwards) into the horizontal area 220. Utilizing the connectivity between the horizontal area 220 and the vertical area 230, it gradually spreads outwards and into the vertical area 230 until the entire anchoring filling space is completely filled and the surface is slightly higher than the reference plane. After the material has initially set, the overflow portion can be smoothed out.

[0035] In this embodiment, the guide member 400 provides precise alignment and temporary positioning during the hoisting stage, preventing significant displacement at the end of the ladder body 200. Secondly, after the anchoring material hardens, the guide member 400, acting as a rigid skeleton penetrating the anchoring hole 210 and the anchoring filling space, together with the anchoring material, forms a high-rigidity anchor body, significantly improving the shear, pull-out, and fatigue resistance of the connection area. Under seismic loading, when the main structure experiences inter-story displacement, the guide member 400 can effectively constrain the relative sliding and rotation of the end of the ladder body 200, forcing the shear force to be transmitted more along the axial direction of the guide member 400 to the main body of the load-bearing beam 100, rather than concentrated at the weak section at the end of the ladder slab. This significantly weakens the conditions for the short column effect, reduces the possibility of concentrated shear failure at the end of the ladder slab, protects the stair components from brittle failure, and maintains the basic integrity of the escape route.

[0036] In one embodiment, the anchoring structure 300 includes: The first anchoring component 310 is capable of filling the anchoring filling space to anchor the ladder body 200 to the corresponding load-bearing beam 100; and... The second anchoring component 320 can be filled into the anchoring hole 210 to fix the ladder body 200 to the load-bearing beam 100.

[0037] Specifically, the first anchoring component 310 mainly fills the anchoring space formed between the high or low end of the ladder body 200 and the corresponding anchoring position of the load-bearing beam 100, and the second anchoring component 320 mainly fills the vertical through anchoring hole 210 reserved at the end of the ladder body 200. After the construction is completed, the two anchoring components are connected to each other and hardened as a whole to form a unified anchoring connection system.

[0038] After the ladder body 200 is hoisted into place, its high and low ends overlap the anchorage positions of the load-bearing beam 100. The anchorage filling space includes interconnected horizontal areas 220 and vertical areas 230. Multiple vertically arranged guide members 400 are pre-embedded at the anchorage positions of the load-bearing beam 100. The guide members 400 extend into the horizontal area 220 and are inserted into the anchorage holes 210 of the ladder body 200 in a corresponding manner. The anchorage holes 210 penetrate the full thickness of the ladder slab, and the guide members 400 are inserted into the holes with an annular gap.

[0039] During construction, the anchoring area is first treated by removing dust, oil, and water from the inner wall of the anchoring hole 210, the surface of the guide member 400, and the contact surface of the anchoring filling space to ensure a clean interface. Then, the anchoring material is prepared, typically using a material with high fluidity, high strength, and no shrinkage or slight expansion properties. The pouring sequence is generally to slowly inject the anchoring material into the opening of the anchoring hole 210 on the upper surface (high end) or lower surface (low end) of the ladder body 200. Under gravity and appropriate vibration, the material first flows downwards (or upwards) along the anchoring hole 210, gradually wrapping around the outer surface of the guide member 400 and filling the annular gap between the hole wall and the guide member 400, until it fills the entire anchoring hole 210 and forms a material layer of a certain thickness at the bottom or top of the hole. This part constitutes the second anchoring component 320. After hardening, the second anchoring component 320, together with the guide member 400, forms a rigid anchoring column that penetrates the thickness of the ladder slab, achieving reliable interlocking and bonding with the concrete of the ladder body 200.

[0040] As the anchoring material continues to be poured and overflows from the other end of the anchoring hole 210, the material naturally enters the horizontal region 220 and the vertical region 230 of the anchoring filling space. It then spreads outwards through the connectivity of these two regions, gradually filling the entire anchoring filling space until its surface is slightly higher than the reference surface of the anchoring position of the load-bearing beam 100 and forms a certain overflow layer. This part constitutes the first anchoring component 310. After the first anchoring component 310 hardens, it forms a large-area bond with the bottom (or top) and sides of the end of the ladder body 200, and also achieves a tight compression connection with the surface of the anchoring position of the load-bearing beam 100 and the protruding part of the pre-embedded guide 400, thereby firmly connecting the ladder body 200 and the load-bearing beam 100 into a whole.

[0041] In this embodiment, through a phased but interconnected construction process, the first anchoring component 310 primarily bears the interface bonding and compression force transmission between the stair body 200 and the load-bearing beam 100, while the second anchoring component 320 primarily provides shear, pull-out, and fatigue restraints penetrating the thickness of the stair slab. The synergistic effect of both significantly improves the overall stiffness and ductility of the connection node. Under normal use, the anchoring structure 300 provides sufficient vertical bearing capacity and horizontal shear resistance to ensure the stability of the staircase. Under seismic loading, when the main structure experiences inter-story displacement, the through-type anchoring column in the second anchoring component 320 can transfer more shear force axially to the main body of the load-bearing beam 100. Simultaneously, the large-area interface bonding of the first anchoring component 310 can disperse local stress concentration, preventing excessive shear force accumulation at the weak sections at the ends of the stair slab. This effectively weakens the conditions for the formation of the short-column effect at the ends, significantly reduces the risk of brittle shear failure of the stair slab due to abrupt changes in stiffness, protects the prefabricated staircase components from severe damage, and helps maintain the basic accessibility of the escape route during earthquakes.

[0042] In one embodiment, the first anchoring member 310 includes: The adjustment pad 311 is placed between the bottom surface of the ladder body 200 and the load-bearing beam 100. The adjustment pad 311 is located in the horizontal area 220 and avoids the guide component 400. Leveling layer 312 fills the horizontal area 220 to fix the calibration pad 311 and the guide member 400; and, The buffer component 313 fills the vertical region 230, and the bottom of the buffer component 313 is connected to the leveling layer 312.

[0043] Specifically, after the ladder body 200 is hoisted into place, an anchoring filling space including a horizontal area 220 and a vertical area 230 is formed between its high or low bottom surface (or top surface) and the anchoring position of the load-bearing beam 100. Multiple guide members 400 arranged vertically are pre-embedded at the anchoring position of the load-bearing beam 100. The guide members 400 have penetrated the anchoring holes 210 of the ladder body 200 and extended into the horizontal area 220. The anchoring structure 300 is divided into a first anchoring component 310 (filling the anchoring filling space) and a second anchoring component 320 (filling the anchoring holes 210).

[0044] During construction, before the ladder body 200 is hoisted or positioned but before large-scale grouting, a leveling shim 311 is placed in the horizontal area 220 of the anchorage position of the load-bearing beam 100, based on the actual measured elevation on site. The leveling shim 311 is generally made of high-strength cement fiberboard, steel plate, or precast concrete thin slab, with the thickness determined according to the actual overlap gap, typically 10mm to 40mm. The leveling shims 311 are arranged in localized blocks or strips, and their placement must avoid all embedded guide components 400. Specifically, a circular or rectangular clearance hole with a diameter or side length 30mm to 60mm larger than the outer diameter of each guide component 400 is reserved around it, ensuring that the leveling shim 311 does not directly contact or compress the guide component 400. The function of the leveling shim 311 is to precisely control the installation elevation of the ladder body 200, ensuring that the ladder slope meets design requirements, and providing a stable lower support surface for the subsequent leveling layer 312.

[0045] After the adjustment pad 311 is positioned and temporarily fixed, the leveling layer 312 is constructed. The leveling layer 312 uses a cement-based grout 321 or special mortar with good fluidity, rapid early strength development, and no shrinkage or slight expansion. The material of the second anchoring component 320, injected from the upper (or lower) end of the anchoring hole 210 of the ladder body 200, continues to overflow into the horizontal area 220 after filling the anchoring hole 210. It first contacts and wraps the lower surface and sides of the adjustment pad 311, while simultaneously filling the gaps between the adjustment pads 311, the annular gap between the adjustment pad 311 clearance holes and the guide member 400, and other gaps in the horizontal area 220 not occupied by the adjustment pads 311. During the hardening process, the leveling layer 312 forms an integral composite layer with the adjustment pad 311, firmly locking the adjustment pad 311 in the predetermined position, and further enhancing the lateral restraint capability of the guide member 400 by wrapping the protruding part of the guide member 400. The final surface of the leveling layer 312 should be slightly higher than the reference surface of the anchorage position of the load-bearing beam 100 and form a grout layer of a certain thickness to facilitate finishing.

[0046] Before the leveling layer 312 initially sets (generally controlled within 30-90 minutes after grouting, depending on the material setting time), buffer components 313 are filled into the vertical area 230 of the anchoring filling space. Buffer components 313 can be made of materials with low elastic modulus but certain compressive strength, such as polyurethane foam, rubber-modified mortar, foamed concrete, or precast elastic blocks. The bottom of the buffer components 313 is in direct contact and bonded to the upper surface of the leveling layer 312. The filling height is generally consistent with the actual height of the vertical area 230, typically 5mm-30mm. Filling methods can include on-site foaming, precast block embedding, or troweling to ensure effective contact between the buffer components 313 and the side ends of the ladder body 200 and the lateral limiting surfaces of the load-bearing beam 100.

[0047] In this embodiment, the structure formed through phased construction ensures accurate elevation of the first anchoring component 310 under normal use by relying on the leveling pad 311 to guarantee precise elevation and the leveling layer 312 to provide large-area rigid bonding and compression force transmission, meeting the bearing and stability requirements under conventional static loads. Under seismic action, when the main structure experiences inter-story displacement or the ends of the staircase 200 exhibit slight relative rotation and shear deformation tendencies, the low stiffness of the buffer component 313 allows for a certain amount of controlled compression or shear deformation, thereby absorbing and dissipating some of the seismic input energy and reducing the instantaneous peak shear stress transmitted to the concrete at the ends of the staircase. Simultaneously, the composite rigid layer of the leveling pad 311 and the leveling layer 312 effectively limits excessive deformation, preventing excessive nonlinear slippage or pull-out at the connection nodes. In this way, the abrupt change in end stiffness is mitigated to a certain extent, the conditions for the formation of the short column effect are weakened, and the risk of concentrated shear failure at the ends of the staircase is further reduced, which is beneficial for protecting the precast staircase components from severe brittle failure and preserving more possibilities for the rapid evacuation of personnel along the staircase during an earthquake.

[0048] In one embodiment, the buffer assembly 313 includes a polystyrene board 314, a PE rod 315, and an adhesive layer 316, which are filled sequentially from bottom to top within the vertical region 230.

[0049] Specifically, the buffer assembly 313 includes, from bottom to top, a polystyrene board 314, a PE rod 315, and an adhesive layer 316. The three components together fill the vertical area 230 of the anchoring filling space, forming a reliable connection with the top of the aforementioned leveling layer 312. This creates a buffer system with layered and variable stiffness between the side of the end of the ladder body 200 and the lateral limiting surface of the anchoring position of the load-bearing beam 100.

[0050] After the ladder body 200 is hoisted into place, the vertical area 230 of the anchoring filling space is mainly located between the side of the end of the ladder body 200 and the lateral limiting surface of the anchoring position of the load-bearing beam 100, with a height of generally 5mm to 30mm; the leveling layer 312 of the first anchoring component 310 has filled the horizontal area 220 and forms an integral composite layer with the adjustment pad 311 and the guide component 400, and its top surface (or bottom surface) serves as the direct lower support surface of the buffer component 313.

[0051] During construction, after the leveling layer 312 has been poured and reached the initial setting stage but not yet fully set (usually 30-120 minutes after pouring, depending on the setting time of the grout 321 used), the vertical area 230 is filled in layers. First, pre-cut polystyrene board strips (or blocks) adapted to the actual height and length of the vertical area 230 are embedded segment by segment into the bottom of the vertical area 230, so that the lower surface of the polystyrene board 314 is tightly attached to the top surface of the leveling layer 312. The thickness of the polystyrene board 314 generally accounts for 40% to 60% of the total height of the vertical area 230. Flame-retardant polystyrene board 314 with a density of 18-25 kg / m³ is commonly used. An interface agent can be pre-coated on the surface to enhance the adhesion with the upper and lower layers. After the polystyrene board 314 is embedded, its upper surface should be basically flat, and a small gap (about 1 to 3 mm) should be left between it and the side of the ladder body 200 and the lateral limiting surface of the load-bearing beam 100, so as to allow for subsequent material filling.

[0052] Next, PE rods 315 are placed or embedded on the upper surface of the polystyrene board 314. PE rods 315 are typically round or rectangular high-density polyethylene rods with a diameter or side length 0.6 to 0.9 times the width of the vertical region 230, and their length corresponds to the corresponding section of the vertical region 230. The PE rods 315 may be pre-cut with shallow longitudinal grooves or have their surfaces roughened to increase the gripping force with the adhesive layer 316. During placement, the lower surface of the PE rod 315 should be firmly attached to the upper surface of the polystyrene board 314; if necessary, a small amount of structural adhesive can be used for temporary fixation. The thickness of the PE rod 315 generally accounts for 20% to 40% of the total height of the vertical region 230, and its compressive modulus is between that of the polystyrene board 314 and the adhesive layer 316, serving as a transition layer.

[0053] Finally, a low-modulus, high-elasticity adhesive is used to fill all remaining gaps on the upper surface of the PE rod 315 and between the polystyrene board 314, the PE rod 315, and the side components (the side of the ladder body 200 and the lateral limiting surface of the load-bearing beam 100), forming an adhesive layer 316. Commonly used materials are single-component or two-component polyurethane sealant, silicone structural adhesive, or modified epoxy flexible adhesive, with a Shore hardness generally between 20 and 50. The adhesive is applied using a dedicated caulking gun, slowly injecting it from the pre-drilled injection holes in the upper or side of the vertical area 230. A thin sheet or special tool is used to assist in venting air during injection, ensuring that the adhesive completely fills all gaps and forms a continuous, void-free bond with the polystyrene board 314, the PE rod 315, and the concrete surfaces on both sides. The surface of the adhesive layer 316 should be slightly raised and smoothed to form a flat protective layer. After the adhesive layer 316 has fully cured (usually 24–72 hours), any excess can be trimmed as needed.

[0054] In this embodiment, through a construction process of filling from bottom to top, the buffer component 313 provides stable lateral support and maintains the geometric stability of the nodes by relying on the synergistic compression of each layer of material under normal use. Under rare earthquake action, when the main structure experiences large inter-story displacement or the ends of the ladder body 200 show a significant relative rotation trend, the polystyrene board 314 first undergoes large compression deformation to absorb the initial stage of earthquake input energy. Subsequently, the PE rod 315 enters the compression stage, further dissipating energy and limiting the deformation rate. The uppermost adhesive layer 316, with its high elasticity and bonding performance, constrains overall slippage and prevents through cracks or local voids from occurring. In this way, the stiffness gradient characteristics of the three-layer material from soft to hard and from large deformation to small deformation make the lateral stiffness of the end connection node present a gradual and non-abrupt distribution. This effectively alleviates the short column effect caused by abrupt stiffness changes in traditional rigid connections, significantly reduces the possibility of concentrated shear failure of the concrete at the end of the stair slab under seismic shear force, thus better protecting the precast stair components from brittle fracture and providing a higher guarantee for the continued usability of the staircase as an escape route during earthquakes.

[0055] In one embodiment, the adhesive layer 316 is located on top of the PE rod 315, and the top surface of the adhesive layer 316 is at the same elevation as the top surface of the ladder body 200.

[0056] Specifically, after the ladder body 200 is hoisted into place, the vertical area 230 of the anchoring filling space is formed between the side of the end of the ladder body 200 and the lateral limiting surface of the anchoring position of the load-bearing beam 100. The buffer assembly 313 has been filled in the vertical area 230 in the order from bottom to top with polystyrene board 314, PE rod 315 and injection layer 316. The bottom of the polystyrene board 314 is connected to the top surface of the leveling layer 312, the PE rod 315 is placed on the polystyrene board 314, and the injection layer 316 covers the top of the PE rod 315 and fills all remaining gaps.

[0057] During construction, after the polystyrene board 314 and PE rod 315 are embedded and initially fixed, before injecting adhesive into the remaining space of the vertical area 230, the expected top surface elevation of the adhesive layer 316 must be accurately measured and marked. This elevation is consistent with the top surface of the ladder body 200 (i.e., the tread surface or platform surface), and is usually marked with a horizontal control line on the side of the end of the ladder body 200 and the lateral limiting surface of the load-bearing beam 100 using a laser level or a level as a pouring reference. Low-modulus, high-ductility sealant (such as polyurethane or modified silicone sealant) is used for adhesive injection, and is slowly and continuously injected through the pre-reserved injection holes in the upper or side of the vertical area 230. A uniform injection speed is maintained, and thin steel sheets or special air venting tools are used to help remove air bubbles, ensuring that the adhesive gradually fills all the gaps between the top of the PE rod 315 and the top surface of the ladder body 200, as well as the small gaps between the side component surfaces and the PE rod 315 and polystyrene board 314, from bottom to top.

[0058] Due to the thixotropic and self-leveling properties of the adhesive material, under gravity and slight manual assistance, the adhesive will form a continuous covering layer on the top surface of the PE rod 315 and gradually flow upwards to the preset elevation. Construction workers use a ruler or aluminum alloy straightedge to smooth the surface of the adhesive layer 316 along the control line in real time, ensuring that its final top surface is precisely flush with the top surface of the stair body 200, forming a smooth, uneven transition surface. After the adhesive is applied, any excess adhesive that has overflowed onto the top surface of the stair body 200 or the surface of the load-bearing beam 100 is immediately cleaned with a damp cloth or special tools to avoid affecting subsequent finishing work. After the adhesive layer 316 has fully cured (usually 24–72 hours, depending on the ambient temperature and type of adhesive), its top surface and the top surface of the stair body 200 form a continuous interface at the same elevation.

[0059] In this embodiment, by strictly controlling the top surface of the adhesive layer 316 to be at the same elevation as the top surface of the stair body 200, this structure can ensure a smooth and continuous surface in the joint area under normal use conditions, avoiding obvious height differences or grooves. This is beneficial for the smooth laying of subsequent finishing materials such as treads, skirting boards, or waterproof layers, reducing the accumulation of construction errors and the risk of hollowing and cracking later. Under seismic action, when the end of the stair body 200 experiences a slight relative rotation or lateral displacement, the flush connection between the top surface of the adhesive layer 316 and the top surface of the stair body 200 allows the seismic shear deformation to be coordinated more by the shear deformation of the adhesive layer 316 itself, rather than being concentrated at the abrupt cross section of the concrete at the end of the stair slab. As the top layer of the buffer component 313, the adhesive layer 316 not only continues the graded energy dissipation characteristics of the polystyrene board 314 and PE rod 315 below, but also further constrains the local warping and tearing trend of the end concrete through the continuous elevation interface with the top surface of the stair body 200. It effectively suppresses the initiation and expansion of concentrated shear cracks at the end caused by the short column effect, thereby protecting the end of the stair slab from brittle failure to a greater extent and maintaining the overall integrity and escape function of the prefabricated staircase under rare earthquakes.

[0060] In one embodiment, the leveling layer 312 is made of cement mortar with a strength grade of A, where A ≥ M15.

[0061] Specifically, after the ladder body 200 is hoisted into place, the horizontal area 220 of the anchoring filling space is mainly formed between the bottom (or top) surface of the ladder body 200 and the anchoring position of the load-bearing beam 100. It contains an adjustment pad 311 and multiple embedded guide components 400. The leveling layer 312, as the core filling material of the first anchoring component 310, needs to simultaneously wrap the lower surface and sides of the adjustment pad 311, fill the gaps between the adjustment pads 311, fill the annular gap between the adjustment pad 311 clearance hole and the guide component 400, and achieve material communication with the subsequently injected second anchoring component 320 at the overflow point of the anchoring hole 210.

[0062] During construction, after the leveling plate 311 is installed and temporarily fixed according to the measured elevation, cement mortar is prepared. The cement mortar uses a strength grade of not less than M15, usually 42.5 or 52.5 grade ordinary Portland cement, with medium sand (fineness modulus 2.3-2.8) as the fine aggregate. The mortar mix ratio can be adjusted according to the weight ratio of cement:sand:water = 1:2.5-3.0:0.45-0.55, and an appropriate amount of water-reducing agent and micro-expansion agent are added (expansion rate controlled at 0.02%-0.10%) to ensure that the mortar has good fluidity (spread 220-260mm), water retention and early strength development characteristics. After preparation, it is thoroughly mixed with a mixer until the color is uniform and there are no lumps.

[0063] Before grouting, all contact surfaces within the horizontal area 220 (including the surface of the adjustment pad 311, the outer surface of the guide component 400, the bottom surface of the ladder body 200, and the surface of the anchoring position of the load-bearing beam 100) are treated with interface treatment: high-pressure water washing is used to remove floating dust, oil stains, and loose particles. If necessary, an interface agent is applied or the surface is roughened to improve adhesion. Subsequently, high-flowability grout 321 is slowly injected into the second anchoring component 320 from the upper (or lower) end of the anchoring hole 210 of the ladder body 200. After it fills the anchoring hole 210 and overflows from the hole into the horizontal area 220, cement mortar is continued to be poured as the main material of the leveling layer 312. Under the influence of gravity and appropriate vibration (using a small-diameter vibrator or plate vibrator), cement mortar gradually fills all voids within the horizontal area 220: First, it wraps the lower surface and sides of the adjustment pad 311, forming bottom support and lateral constraint for the adjustment pad 311; then, it fills the joints between the adjustment pads 311 and the annular gap between the clearance holes and the guide members 400, ensuring that the protruding part of each guide member 400 is completely wrapped by mortar and forms a protective layer of not less than 15mm; finally, the mortar continues to flow upwards until the horizontal area 220 is completely filled, with the surface slightly higher than the reference plane of the anchorage position of the load-bearing beam 100 by 5-10mm, forming a certain overflow layer. During construction, it should be poured in layers, with each layer thickness controlled within 150mm, and the interval between layers not exceeding the initial setting time (generally 1-2 hours) to avoid cold joints. After the mortar is poured, use an aluminum alloy straightedge to smooth the surface around the 100mm anchorage position of the load-bearing beam, and cover it with plastic film or sprinkle water for curing for no less than 7 days to ensure that the mortar is fully hydrated and reaches the design strength.

[0064] By using cement mortar with a strength grade of A≥M15 as the leveling layer 312 material, this structure can provide sufficient compressive strength and interfacial bonding force under normal use conditions, so that the leveling pad 311, the guide 400 and the adjacent concrete surface form an integral composite force system, effectively transferring the load at the end of the stair slab to the load-bearing beam 100. Under seismic action, when the joint is subjected to large shear and local compression, the cement mortar with a strength grade of M15 and above has high shear bearing capacity and crack resistance, which can limit the premature propagation of micro-cracks inside the leveling layer 312. At the same time, by gripping the guide 400 over a large area and stably locking the leveling pad 311, the overall rigidity and resistance to lateral deformation of the first anchoring component 310 are further enhanced. The leveling layer 312 can ensure reliable force transmission at the connection nodes under static loads, and can also work in conjunction with the buffer component 313 in rare earthquakes to weaken the short column effect caused by sudden changes in end stiffness, reduce the risk of concentrated shear failure at the end of the stair slab, and thus significantly improve the overall lateral force resistance and component protection capabilities of the precast staircase under seismic conditions.

[0065] In one embodiment, the anchoring hole 210 is arranged to gradually decrease in length from top to bottom along the vertical direction.

[0066] Specifically, after the ladder body 200 is hoisted into place, the anchoring holes 210 reserved at its high or low end correspond to the guide members 400 embedded in the anchoring position of the load-bearing beam 100. The guide members 400 have penetrated the anchoring holes 210 and extended into the horizontal area 220. The material of the second anchoring component 320 is injected from the upper (or lower) end of the anchoring hole 210, filling the entire anchoring hole 210 and overflowing into the horizontal area 220, connecting with the leveling layer 312 material to form an integral whole. The first anchoring component 310 fills the horizontal area 220 and the vertical area 230.

[0067] During the factory fabrication stage of precast stair components, the anchoring holes 210 are pre-formed using a special steel mold or a detachable mandrel. The steel mold is designed vertically as a tapered shape or a multi-segment zigzag tapering form with the cross-sectional dimensions gradually decreasing from top to bottom. The upper opening is generally 40-80mm larger than the outer diameter of the guide component 400, while the lower opening narrows to 15-35mm larger than the outer diameter of the guide component 400. The taper is controlled between 1:50 and 1:20 (i.e., the hole diameter decreases by 2-5mm for every 100mm downward). The specific tapering method can be a straight tapered shape, a stepped multi-stage diameter reduction, or a smooth curved tapering. The hole wall surface should be flat and without obvious bumps or depressions. If necessary, a release agent is applied to the inner surface of the mold. When pouring the concrete for the stair body 200, the steel mold or mandrel is positioned and fixed at the predetermined position at the end of the stair slab. After the concrete is vibrated and compacted, it is cured and demolded, forming the anchoring holes 210 with the cross-section gradually decreasing from top to bottom vertically. Before on-site hoisting, the inner wall of the anchor hole 210 should be cleaned to remove floating dust, release agent residue and loose particles. If necessary, the surface should be slightly roughened with a wire brush to improve the bonding force of the subsequent grouting material 321.

[0068] After hoisting into place and completing the construction of the leveling plate 311 and leveling layer 312, the second anchoring component 320 is grouted. A special grouting material 321 with high fluidity, no shrinkage or slight expansion (compressive strength ≥60MPa, fluidity ≥260mm) is slowly and continuously injected from the top of the anchoring hole 210. Benefiting from the gradually narrowing geometry of the anchoring hole 210 from top to bottom, the cross-section of the grouting material 321 gradually decreases as it flows downwards under gravity, leading to a gradual increase in grout velocity and a gradually increasing lateral compressive force on the hole wall. The upward return of the grout after filling the lower, smaller cross-sectional area is also constrained by the narrowing wall surface, making it easier for air bubbles to escape upwards along the wall, significantly reducing the probability of residual air bubbles and voids in the hole. After the grout overflows from the orifice, continue to inject under low pressure for several minutes to ensure that the grout fully fills all the tiny gaps in the tapering section and forms a tight wrap with the outer surface of the guide 400; the overflowing grout automatically flows into the horizontal area 220 and connects with the leveling layer 312 material to harden.

[0069] The anchoring holes 210 are arranged vertically from top to bottom in a gradually decreasing manner. Under normal use, this structure can create a gradually increasing bond force and compressive stress distribution between the second anchoring component 320 and the concrete of the ladder body 200, improving the pull-out resistance and shear bearing capacity of the connection interface. Under seismic action, when the end of the ladder body 200 is subjected to upward pull-out or lateral shear force, the gradually decreasing hole wall produces a "wedge-shaped self-locking" constraint effect on the grout 321 column. The grout at the smaller lower section is first subjected to greater lateral compressive constraint, which limits the overall slippage and pull-out deformation of the grout 321 column. At the same time, the decreasing geometry makes the contact area between the grout 321 and the hole wall non-uniformly distributed along the depth. The larger contact surface at the top helps to disperse the initial shear stress, while the stronger compressive zone at the bottom effectively prevents the rapid propagation of cracks along the interface. The anchoring hole 210 and the second anchoring component 320 together form an anchoring system with gradually changing stiffness and increasing constraint along the depth direction. This effectively alleviates the early bond failure or pull-out failure caused by interface stress concentration in traditional straight holes with uniform cross-sections. It significantly improves the pull-out resistance and shear resistance of the end nodes under rare earthquakes, and reduces the risk of brittle spalling or overall pull-out of the concrete at the end of the stair slab due to anchoring failure. This further ensures the connection reliability and personnel evacuation function of the precast staircase under extreme loads.

[0070] In one embodiment, the second anchoring member 320 includes: Grouting material 321 is filled into the anchoring hole 210 to connect the guide member 400 and the ladder body 200 into one unit; and, The mortar sealing layer 322 fills the anchor hole 210 and is located on top of the grouting material 321, and the top elevation of the mortar sealing layer 322 is consistent with the top elevation of the ladder body 200.

[0071] Specifically, after the ladder body 200 is hoisted into place, the guide component 400 has penetrated the anchor hole 210 and extended into the horizontal area 220. The anchor hole 210 is set to gradually narrow from top to bottom vertically. The second anchor component 320 is responsible for firmly connecting the guide component 400 to the ladder body 200, and at the same time, it achieves material communication with the first anchor component 310 (leveling layer 312) at the overflow point of the anchor hole 210. The buffer component 313 has been filled in the vertical area 230, and the leveling layer 312 has completed the filling of the horizontal area 220.

[0072] During construction, a high-flowability grout 321 is first prepared. Typically, a non-shrink or micro-expansion cement-based grout 321 with a compressive strength ≥60MPa and an initial flowability ≥260mm is selected. An appropriate amount of early-strength agent and water-reducing agent can be added to control the setting time within the range of 30–90 minutes. After cleaning the hole, the grout 321 is slowly and continuously injected from the upper end of the anchoring hole 210 (or from the lower end depending on site conditions) using pressure grouting or gravity grouting. Under the action of gravity and slight pressure, the grout 321 gradually fills the tapered anchoring hole 210 from top to bottom: first filling the lower, smaller cross-sectional area, forming a strong lateral compression and wrapping around the lower section of the guide member 400; then returning upwards, gradually filling the middle and upper, larger cross-sectional area until a stable overflow appears at the hole opening (the overflow flow is stable and no obvious bubbles emerge). At this point, stop grouting, but maintain a low pressure for 3-5 minutes to ensure that the grout is fully compacted and forms a continuous, void-free bonding interface with the converging hole wall and the outer surface of the guide 400. The overflowing grout 321 automatically flows into the horizontal area 220, where it connects and hardens with the leveling layer 312 cement mortar to form an integral composite anchor body.

[0073] When the grouting material 321 has initially set but not yet fully set (generally 1.5 to 4 hours after grouting, depending on the type of material and ambient temperature; the surface will leave a slight fingerprint but will not be sticky), begin preparing the cement mortar for the sealing layer 322. The mortar should be of the same or similar strength grade as the leveling layer 312 (M15 to M30), with a mix ratio of cement:sand:water = 1:2.5 to 3.0:0.45 to 0.50. The slump should be controlled at 80 to 120 mm, and appropriate amounts of polycarboxylate superplasticizer and micro-expansion agent should be added. Using a special small shovel or grouting gun, fill the mortar in stages into the top space of the initially set grouting material 321 from the top of the anchoring hole 210, gently tamping it down with a thin steel bar or bamboo strip while filling to remove any trapped air. The filling height should be slightly higher than the top surface of the stair body 200 by 5-8mm. Then, use an aluminum alloy straightedge or trowel to smooth and finish the surface along the horizontal control line around the top surface of the stair body 200, ensuring the final top surface of the mortar sealing layer 322 is precisely at the same elevation as the top surface (tread or platform surface) of the stair body 200. During construction, prevent mortar from contaminating the completed finish of the stair body 200; if necessary, temporarily apply protective tape around the opening. After sealing, cover with damp burlap sacks or plastic film and cure with water for at least 3 days to prevent early drying shrinkage and cracking.

[0074] By setting a mortar sealing layer 322 on top of the grouting material 321 and strictly controlling its top surface to be at the same elevation as the top surface of the ladder body 200, a smooth and continuous node surface can be formed under normal use conditions, avoiding pits or height differences at the anchor hole 210. This facilitates the overall laying of the subsequent floor leveling layer 312, surface layer, or waterproof layer, reducing the risk of surface hollowing, cracking, and leakage. Under seismic action, when the end of the ladder body 200 tends to pull upward or undergo lateral shear deformation, the lower grouting material 321 section relies on gradual contraction... The progressively reinforcing constraint of the borehole wall first provides the main pull-out and shear bearing capacity, while the upper mortar sealing layer 322, with its continuous interface with the top surface of the ladder body 200 and good early stiffness, restricts the local warping and tearing of the top area of ​​the grouting material 321 column, and delays the upward propagation of interface cracks. At the same time, the material transition zone (initial setting overlap surface) formed between the mortar sealing layer 322 and the grouting material 321 can achieve a smooth stress transfer, avoiding concentrated cracking caused by the sudden change in stiffness of the single high-strength grouting material 321 at the borehole opening. The second anchoring component 320 exhibits a composite characteristic of high constraint and high strength at the bottom and flatness and coordinated deformation at the top. It effectively suppresses early peeling and pull-out damage at the orifice interface, which is common in the traditional straight hole full grouting material 321 system. It further improves the pull-out resistance, shear ductility and surface integrity of the end nodes under rare earthquakes, and reduces the risk of brittle spalling or overall instability caused by anchoring failure at the end of the stair slab. Thus, it provides a more comprehensive structural guarantee for the connection durability and escape route reliability of precast stairs under extreme loads.

[0075] Based on the same technical concept, the second aspect of the present invention also proposes a construction method for a prefabricated staircase, used for constructing the prefabricated staircase of the first aspect, the construction method comprising the following steps: S100. In the pre-designed construction area, reinforced concrete is poured in place to form two load-bearing beams that are spaced apart vertically; wherein, each load-bearing beam has an anchorage position, and the two anchorage positions are opposite to each other and staggered vertically. S200. After the load-bearing beams reach the preset strength, the ladder body is hoisted and installed at the anchoring positions of the two load-bearing beams; wherein, an anchoring filling gap is formed between the high end and the low end of the ladder body and the corresponding anchoring position. S300. Anchoring structures are constructed within the two anchoring filling gaps to complete the installation of the ladder body.

[0076] Specifically, the final connection nodes of the precast staircase include the anchoring position on the load-bearing beam, the anchoring hole at the end of the staircase body, the guide component passing through it, the first anchoring component (leveling layer) and the second anchoring component (grouting material and mortar sealing layer) in the horizontal and vertical areas, and the buffer components (polystyrene board, PE rod, and adhesive injection layer) in the vertical area; the anchoring filling gap is formed by the vertical area formed between the side of the end of the staircase body and the lateral limiting surface of the anchoring position of the load-bearing beam, and the horizontal area formed between the bottom (or top) surface of the end of the staircase body and the anchoring position of the load-bearing beam.

[0077] Construction begins with setting up formwork at the designated floor levels, tying the reinforcing cages for the load-bearing beams, and pre-embedding guide components (usually threaded or plain round steel bars or steel anchors, with lengths determined by calculation, extending at least 300mm beyond the top or side of the load-bearing beam) at the anchorage positions of the load-bearing beams. The load-bearing beams are cast-in-place using C30-C50 concrete, compacted by vibration, covered with plastic film, and watered for curing. The ladder body can only be hoisted when the concrete compressive strength reaches more than 80% of the design strength (generally 7-14 days, depending on the mix proportion and ambient temperature) and there are no obvious cracks on the surface.

[0078] Before hoisting, clean the anchor holes at the ends of the ladder body and measure the actual elevation of the top (or side) of the anchorage position of the load-bearing beam. Calculate the thickness of the leveling pads and the expected thickness of the leveling layer. Use a truck crane or tower crane to hoist the entire ladder body to the installation position and lower it slowly, aligning the high end of the ladder body with the anchorage position of the upper load-bearing beam and the low end with the anchorage position of the lower load-bearing beam. During the lowering process, the guide components should accurately pass through the anchor holes at the ends of the ladder body and extend into the reserved space in the horizontal area. After the ladder body is in place, use temporary supports or adjustable brackets for initial fixation. Use a theodolite or laser line projector to verify the longitudinal and transverse positions, elevation, and verticality of the ladder body, ensuring the error is within the allowable range specified in the standards. Subsequently, in the horizontal area, place the leveling pads in sequence and pour the leveling layer cement mortar (strength grade M15 or higher). After the leveling layer has initially set, embed polystyrene boards and PE rods in the vertical area from bottom to top, leaving space for the adhesive layer.

[0079] After the leveling layer reaches a certain strength (generally 3-7 days after grouting), the second anchoring component is constructed: high-flowability grout is pressure-injected from the upper (or lower) end of the anchoring hole until it overflows into the horizontal area and connects with the leveling layer; after the grout has initially set, a mortar sealing layer is filled at the top of the anchoring hole and leveled to the same elevation as the top surface of the staircase. Finally, adhesive is injected into the remaining space in the vertical area to form a continuous interface where the top surface of the adhesive layer is flush with the top surface of the staircase. After all anchoring structures are completed, the temporary supports are removed, and subsequent floor construction and finishing processes begin.

[0080] By employing a step-by-step, orderly construction method, a reliable rigid-flexible composite anchoring system can be ensured between the load-bearing beam and the staircase body. Under normal use, the second anchoring component provides the main resistance to pull-out and shear bearing capacity, while the first anchoring component (leveling layer) achieves uniform load transfer and interface stability. The buffer component absorbs local stress concentration at the node through graded compression deformation, resulting in a reasonable overall connection stiffness distribution. This avoids the problems of long construction cycles and large quality dispersion in traditional cast-in-place staircase nodes. Under seismic loading, when the node is subjected to large inter-story displacement or shear deformation, the polystyrene board, PE rod, and grouting layer in the vertical area successively play the roles of low stiffness buffering, high ductility energy dissipation, and surface coordination, significantly weakening the end short column effect and delaying the initiation and propagation of concentrated shear cracks in the concrete at the end of the stair slab. At the same time, the tapered anchoring holes and the segmented second anchoring components work together to form progressively stronger constraints, limiting the pull-out deformation of the grout column, while the mortar sealing layer maintains the continuity of the node surface and reduces the risk of local tearing at the hole opening. This construction method, while ensuring installation accuracy, enables the precast staircase end nodes to maintain sufficient load-bearing capacity and deformation coordination under rare earthquakes, effectively protecting the stair slab ends from brittle failure and ensuring the unobstructed escape route and overall structural safety after an earthquake.

[0081] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A prefabricated staircase, characterized in that, The high and low ends of the prefabricated staircase are respectively erected on the load-bearing beams of two adjacent floor slabs, and anchoring positions are provided on both load-bearing beams. The prefabricated staircase includes: The ladder body is a precast reinforced concrete structure. Anchoring holes extending vertically through the ladder body are formed at both its high and low ends. Both the high and low ends of the ladder body can overlap with corresponding anchoring positions, forming an anchoring filling space between them. Two anchoring structures are provided, which can enter and fill the anchoring filling space and the anchoring hole to anchor the ladder body to the corresponding load-bearing beam.

2. The prefabricated staircase as described in claim 1, characterized in that, The anchoring filling space includes interconnected horizontal and vertical areas. Multiple guide members are pre-embedded at the anchoring position and arranged vertically. The guide members are located in the horizontal area. The number of anchoring holes is the same as the number of guide members and they are inserted and matched one-to-one.

3. The prefabricated staircase as described in claim 2, characterized in that, The anchoring structure includes: A first anchoring component, capable of filling the anchoring filling space, thereby anchoring the ladder body to the corresponding load-bearing beam; and... The second anchoring component can be filled into the anchoring hole to fix the ladder body to the load-bearing beam.

4. The prefabricated staircase as described in claim 3, characterized in that, The first anchoring component includes: A calibration pad is placed between the bottom surface of the ladder body and the load-bearing beam. The calibration pad is located in the horizontal area and avoids the guide member. A leveling layer, said leveling layer filling the horizontal area to fix the calibration pad and the guide member; and A buffer component, which fills the vertical area and whose bottom is connected to the leveling layer.

5. The prefabricated staircase as described in claim 4, characterized in that, The buffer assembly includes a polystyrene board, a PE rod, and an adhesive layer, which are filled sequentially from bottom to top within the vertical region.

6. The prefabricated staircase as described in claim 5, characterized in that, The glue injection layer is located on top of the PE rod, and the top surface of the glue injection layer is at the same elevation as the top surface of the ladder body.

7. The prefabricated staircase as described in claim 4, characterized in that, The leveling layer is made of cement mortar, and the strength grade of the cement mortar is A, where A≥M15.

8. The prefabricated staircase as described in any one of claims 3 to 7, characterized in that, The anchoring holes are arranged in a gradually decreasing pattern from top to bottom along the vertical direction.

9. The prefabricated staircase as described in claim 8, characterized in that, The second anchoring component includes: Grouting material, which is filled into the anchoring hole to connect the guide member and the ladder body as a single unit; and, A mortar sealing layer is provided, which fills the anchor hole and is located on top of the grouting material, and the top elevation of the mortar sealing layer is consistent with the top elevation of the ladder body.

10. A construction method for a precast staircase, characterized in that, For constructing prefabricated stairs as described in any one of claims 1 to 9, the construction method comprises the following steps: In the pre-designed construction area, reinforced concrete is poured in place to form two load-bearing beams that are spaced apart vertically; wherein, each load-bearing beam has an anchorage position, and the two anchorage positions are opposite to each other and staggered vertically. After the load-bearing beams reach the preset strength, the ladder body is hoisted and installed at the anchoring positions of the two load-bearing beams; wherein, an anchoring filling gap is formed between the high end and the low end of the ladder body and the corresponding anchoring position. Anchoring structures are constructed within the two anchoring gaps to complete the installation of the ladder body.

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