Fabricated stair anti-seismic structure and construction method thereof

Abstract

The invention discloses a fabricated stair anti-seismic structure and a construction method thereof, a double-wing-plate integrated stair anti-seismic deepened design is adopted, trapezoidal wing plate shear walls and prefabricated column post-cast nodes are used for strengthening and cooperatively bearing, and outer extending steel bars at the end parts of transverse stair beams are provided with anchor plates; pre-embedded tie bars of a prefabricated column body are in butt joint with transverse distribution steel bars of a T-beam wing plate to form a post-cast joint, the unbonded prestressed tendons are integrally formed in a built-in mode, perforated, tensioned and anchored, the lowermost unbonded prestressed tendons stretch across the trapezoidal wing plate shear wall, the oblique ladder beam and the transverse ladder beam, and a laminated slab connecting joint is connected through pre-embedded steel bars in supporting holes and additionally provided with anchoring plates. And a high-strength grouting material hole sealing process is adopted, so that a double-wing-plate integrated stair collaborative main body structure anti-seismic system is constructed, and the overall anti-seismic performance of the fabricated building is improved.

Description

Technical Field

[0001] This invention relates to the field of prefabricated buildings, specifically to a prefabricated staircase earthquake-resistant structure and its construction method. Background Technology

[0002] In recent years, with the continuous improvement of the level of industrialization in the construction industry, prefabricated concrete structures have become an important direction for the transformation and upgrading of the construction industry due to their advantages such as fast construction speed, less on-site wet work, and strong quality control. However, in earthquake-prone areas, the seismic performance of prefabricated buildings, especially the seismic reliability of key escape routes—staircases, still faces severe challenges.

[0003] Traditional cast-in-place staircases have a natural advantage in terms of overall integrity, while existing prefabricated staircases mostly use simple placement or hinged connections, lacking an effective collaborative force-bearing mechanism with the main structure. In the event of an earthquake, the staircases are highly susceptible to fracture, slippage, or even collapse due to insufficient joint stiffness, connection failure, or localized stress concentration, seriously threatening the safety of personnel evacuation. Furthermore, some current prefabricated systems unilaterally emphasize the design concept of "equivalent to cast-in-place," neglecting the unique characteristics of prefabricated components in terms of joint construction, construction deviation control, and post-earthquake repairability, leading to problems such as "ideal design, disjointed construction, and difficulties in acceptance" in actual projects.

[0004] Specifically, existing prefabricated staircases face the following technical bottlenecks: (1) The connection between the staircase and the main structure is weak, making it difficult to form an effective force transmission path; (2) The hoisting accuracy requirements are high during the construction process, but the skills of the operators vary, which can easily cause deviations in the placement of components and affect the overall structure. (3) The staircase itself lacks independent lateral resistance and is prone to failure when the main structure undergoes large deformation, thus losing its escape function; (4) Post-earthquake damage is difficult to assess, repair costs are high, and in some cases, the entire structure may need to be demolished and rebuilt.

[0005] To address the aforementioned issues, while the industry has attempted to improve stair joint performance by adding shear keys, pre-embedded sleeves, or post-cast strips, these approaches often focus only on strengthening local connections and fail to achieve "integrated seismic synergy" between the staircase and the main structure at the system level. Especially in high-intensity earthquake zones, there is an urgent need for a new type of prefabricated staircase structure system that can ensure both ease of construction and the stability and usability of the staircase under seismic loads. Summary of the Invention

[0006] The purpose of this invention is to provide a prefabricated staircase earthquake-resistant structure and its construction method to solve the problems raised in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a prefabricated staircase earthquake-resistant structure, comprising prefabricated columns, composite slabs, and a double-wing integrated staircase disposed between the prefabricated columns, wherein the prefabricated columns are provided with embedded tie rods and reserved holes; The double-wing plate integrated staircase is prefabricated as a whole in the prefabricated PC factory, including stair sections, horizontal ladder beams, inclined ladder beams, trapezoidal wing plate shear walls and unbonded prestressed tendons. The horizontal ladder beams are located at the upper and lower ends of the stair sections, and the extended steel bars of the horizontal ladder beams are provided with anchor plates for connecting with the truss bars of the composite plate. The inclined stair beams are located on the left and right sides of the stair section, and the trapezoidal wing shear wall is located on the upper side of the inclined stair beams. The trapezoidal wing shear wall has transversely distributed reinforcing bars extending outward on both sides, and its top surface is horizontal and has masonry. A post-cast section is provided between the trapezoidal wing shear wall and the adjacent precast column, and the embedded tie bars are connected to the transversely distributed reinforcing bars of the trapezoidal wing shear wall in the post-cast section. The unbonded prestressed tendons are inserted through the trapezoidal wing shear wall, the post-cast section, and the reserved holes, and are tensioned and anchored to the outside of the precast column or the bottom of the inclined ladder beam by anchors.

[0008] Preferably, the trapezoidal wing shear wall has a trapezoidal cross-section, and its thickness is equal to the width of the inclined ladder beam. The vertical distributed reinforcement of the trapezoidal wing shear wall extends from the inside of the inclined ladder beam. The bottom inclined design angle of the trapezoidal wing shear wall is consistent with the design angle of the stair section. The vertical side of the trapezoidal wing shear wall in the post-cast section is roughened or keyways are provided, and the roughness is not less than 85%.

[0009] Preferably, the diameter of the embedded tie bar is not less than 8mm and not less than the diameter of the horizontally distributed steel bars inside the trapezoidal wing shear wall, the length of the embedded tie bar is not less than 300mm, and the end is provided with a 180-degree hook; the unbonded prestressed tendon passes through the reserved hole and is anchored to the side of the precast column. The diameter of the reserved hole is 2mm to 3mm larger than the outer diameter of the unbonded prestressed tendon. The position of the reserved hole corresponds one-to-one with the position of the unbonded prestressed tendon inside the trapezoidal wing shear wall, and the installation error shall not exceed 2mm.

[0010] Preferably, the extended reinforcing bars of the transverse ladder beam are achieved by bending the longitudinal reinforcing bars of the stair section and extending them out of the transverse ladder beam, and a double-row design is adopted; the length of the extended reinforcing bars is not less than 600mm, and the lower row of extended reinforcing bars rests on the top of the composite slab truss reinforcement and is fixed to the truss reinforcement by spot welding.

[0011] Preferably, the transverse ladder beam is provided with support holes, and the upper side of the composite plate is provided with a pre-embedded steel rod inserted into the support hole. The diameter of the support hole is not less than 80mm, the diameter of the pre-embedded steel rod is not less than 40mm, and the top of the pre-embedded steel rod is provided with an anchor plate. The top surface elevation of the anchor plate is 3mm~5mm lower than the top surface elevation of the transverse ladder beam. High-strength grout is injected into the cavity between the pre-embedded steel rod and the support hole. The high-strength grout is a micro-expansion low-shrinkage sulfur mortar grout.

[0012] Preferably, part of the bottommost unbonded prestressing tendon is inside the trapezoidal wing shear wall, and the other part is pre-embedded inside the inclined ladder beam. One end of this unbonded prestressing tendon is anchored to the side of the precast column, and the other end is anchored to the bottom of the inclined ladder beam.

[0013] This invention also provides a construction method for a prefabricated staircase seismic-resistant structure, the overall construction process of which is as follows: Step S1: Prefabricate the double-wing integrated staircase in advance and hoist the various components of the frame structure; Step S2: Verify the positional relationship of the pre-embedded steel bars, and hoist the double-wing plate integrated staircase into place; Step S3: Tighten the anchor plate inside the support hole and fill the hole with high-strength grout; Step S4: Tighten the transverse ladder beam end overhanging reinforcement and its end anchor plate, and pour the composite slab concrete; Step S5: Drilling and positioning of unbonded prestressed tendons, and connecting the transverse distributed steel bars of the trapezoidal wing shear wall and the pre-embedded tie bars of the precast columns; Step S6: Post-cast concrete pouring and curing, tensioning and anchoring of unbonded prestressed tendons.

[0014] This invention also provides a construction method for a prefabricated staircase earthquake-resistant structure, and the detailed construction process is as follows: Step S1: Prefabrication of the double-wing integrated staircase; hoisting of various components of the frame structure: The double-wing integrated staircase is prefabricated in a prefabricated PC factory. Using matching molds, the staircase sections, transverse stair beams, inclined stair beams, trapezoidal wing shear walls, and unbonded prestressed tendons are cast in one piece, completing the process in one go without construction joints. The reinforcing bars at the corners of the inclined stair beams and trapezoidal wing shear walls are bent 90 degrees from the inside of the inclined stair beams and extend into the interior of the trapezoidal wing shear wall mold, forming an integrated beam-slab node. The left and right ends of the trapezoidal wing shear wall are 300mm from the corresponding transverse stair beam edges, and their extended transverse reinforcing bars meet design requirements. Requirements: Demolding, hoisting, transportation, and stacking of concrete after it reaches 100% of the design strength; during the process, finished product protection shall be provided for the stair sections, corners of trapezoidal wing shear walls, extended transverse distributed reinforcement, extended reinforcement at the ends of transverse stair beams, and their end anchor plates; the prefabricated building main frame structure shall be hoisted simultaneously to provide a working surface for the overall hoisting of the staircase; the reserved holes and embedded tie bars of the precast columns shall meet the design requirements and be protected; the reserved holes shall be sealed with special rubber plugs before hoisting to avoid affecting the subsequent perforation of unbonded prestressed tendons; Step S2: Verify the positional relationship of the pre-embedded steel bars, and hoist the integrated double-wing staircase into place: After the double-wing integrated staircase is delivered to the site and all prefabricated components of the main frame are hoisted, the positional relationship and outward extension length of the embedded steel bars at the upper and lower ends of the staircase are checked, and hoisting is carried out under controllable error conditions. During the hoisting process, the staircase is slowly positioned to ensure that the embedded steel bars on the composite slab are accurately aligned with the support holes in the transverse ladder beams at the upper and lower ends of the staircase, and the position is repeatedly checked and adjusted. Step S3: Tighten the anchor plate inside the support hole, and fill the hole with high-strength grout. After the double-wing integrated staircase is in place, a high-pressure air gun is used to clean the cavity between the support hole of the horizontal stair beam and the pre-embedded steel bar; the anchor plate is screwed onto the top of the pre-embedded steel bar one by one to ensure that the top elevation meets the requirements; then high-strength grouting material is filled into the cavity between the support hole and the pre-embedded steel bar, and the grouting material fills the cavity and covers the top surface of the anchor plate. Step S4: Tighten the transverse ladder beam end overhanging reinforcement and its end anchor plate, and pour the composite slab concrete: After the high-strength grout reaches its initial setting strength, adjust the extended steel bars at the ends of the transverse ladder beams and their end anchor plates, and then pour the upper concrete of the composite slab. Ensure that each extended steel bar is fitted with an anchor plate. The end anchor plates of the extended steel bars at the ends of the transverse ladder beams and the anchor plates in the support holes are different components. The extended steel bars and anchor plates are poured together in the upper composite layer of the composite slab. The concrete strength of the composite slab is not lower than C35 and is one grade higher than the concrete strength of the double-wing integrated staircase. Step S5: Drilling and positioning of unbonded prestressing tendons; connection of transverse reinforcing bars in trapezoidal wing shear wall and pre-embedded tie bars in precast columns: After the composite slab concrete is poured, the transverse distributed steel bars extending outward at both ends of the trapezoidal wing plate shear wall are welded to the pre-embedded tie bars in the precast column body; the special rubber plugs in the precast column reserved holes are pulled out, and the unbonded prestressed tendons extending outward at both ends of the trapezoidal wing plate shear wall are passed through the precast column reserved holes and temporarily fixed with anchors. Step S6: Post-cast concrete pouring and curing, tensioning and anchoring of unbonded prestressed tendons: After the reinforcement connections and unbonded prestressing tendon insertion holes in the post-cast section are in place, a high-pressure air gun is used to clean the bottom of the post-cast section between the precast column and the trapezoidal wing shear wall. Aluminum formwork is used for support, and low-shrinkage, micro-expansion fine aggregate concrete of not less than C35 is poured in one go without leaving construction joints, and curing is strengthened. After the concrete strength of the post-cast section reaches 100% of the design strength, the unbonded prestressing tendons are tensioned and anchored. The tensioning sequence is to start from the top of the trapezoidal wing shear wall, tensioning one by one from top to bottom, symmetrically, and anchoring as tensioning, and finally tensioning the unbonded prestressing tendons that pass through the inclined ladder beam and inside the trapezoidal wing shear wall. Due to the limited working space, the prestressing tendons in this part are first anchored to the bottom end of the inclined ladder beam, and then anchored to the side of the precast column by tensioning one end. All anchorages are sealed with sulfur mortar high-strength grout. The top surface of the trapezoidal wing shear wall is a horizontal plane, and non-load-bearing walls are directly built on it.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: 1. This invention adopts a structural system composed of precast columns, double-wing slab integrated staircases and composite slabs, and introduces unbonded prestressed tendon technology, which effectively enhances the synergistic seismic resistance between the staircase and the main structure, achieving the design goal of "when an earthquake occurs, the main structure and the staircase will not be damaged, and the main structure and the staircase will not collapse".

[0016] 2. This invention adopts an integrated structural design of trapezoidal wing plate shear wall and inclined stair beam, and roughens the vertical side of the post-cast section or sets keyways, which improves the overall stability and durability of the structure and ensures the safe use of the staircase during an earthquake.

[0017] 3. This invention further strengthens the connection between the staircase and the main frame structure by designing the transverse ladder beam end extension steel bars and their end anchor plates, and by adding anchor plates to the pre-embedded steel bars in the support holes, thereby improving the seismic performance of the overall structure.

[0018] 4. This invention proposes a systematic construction method. From the prefabrication of the double-wing integrated staircase to the on-site hoisting and placement, and then to the perforation, tensioning and anchoring of the unbonded prestressed tendons, each step is carefully designed, reducing construction errors and improving work efficiency and project quality. Attached Figure Description

[0019] Figure 1This is a top view showing the positional relationship between the double-wing integrated staircase and the precast column of the present invention; Figure 2 This is a side view illustrating the positional relationship between the integrated double-wing staircase and the precast columns of this invention. Figure 2 The unbonded prestressed tendons, post-cast sections, and masonry are drawn as visible. Figure 3 This is a simplified structural view of the double-wing integrated staircase of the present invention; Figure 4 This is a top view showing the positional relationship between the double-wing integrated staircase and the composite slab of the present invention; Figure 5 yes Figure 4 Select the sectional view at the support hole; The staircase in the above-mentioned attached figure is a stepped type, and it has been simplified to the form shown in the attached figure for the sake of simplifying the lines. Figure 6 This is a process flow diagram of the construction method of the present invention. Detailed Implementation

[0020] This invention discloses a prefabricated staircase seismic-resistant structure, mainly composed of prefabricated columns 1, a double-wing integrated staircase 2, and composite slabs 31. The prefabricated columns 1 and composite slabs 31 are part of the main building frame. (See also...) Figures 1 to 5 A double-wing integrated staircase 2 is provided between the four precast columns 1. Each precast column 1 is equipped with embedded tie bars and reserved holes. The double-wing integrated staircase 2 is designed and formed as a whole in the prefabricated PC factory, consisting of stair section 21, transverse stair beam 22, inclined stair beam 23, trapezoidal wing shear wall 24, and unbonded prestressed tendons 26. The specific structure is as follows: See Figure 1 and Figure 2 The staircase 21 has two transverse stair beams 22 at its upper and lower ends, and two diagonal stair beams 23 on its left and right sides. The double-wing integrated staircase 2 has outward-extending steel bars at the transverse stair beams 22, and each outward-extending steel bar has an anchor plate 7 at its end. A trapezoidal wing shear wall 24 is provided on the upper side of the diagonal stair beams 23. The trapezoidal wing shear wall 24 and the diagonal stair beams 23 are an integrated structure, and the two are cast together with concrete.

[0021] The transverse reinforcing bars at both ends of the trapezoidal wing shear wall 24 extend outwards. The top surface of the trapezoidal wing shear wall 24 is horizontal and has masonry 5 on top. A post-cast section 4 is provided between the trapezoidal wing shear wall 24 and two adjacent precast columns 1. The embedded tie bars on the precast columns 1 and the transverse reinforcing bars at both ends of the trapezoidal wing shear wall 24 are in a one-to-one correspondence and are firmly connected in the post-cast section 4. The unbonded prestressed tendons 26 inside each trapezoidal wing shear wall 24 pass through the pre-reserved holes in the post-cast section 4 and the precast columns 1. Finally, the unbonded prestressed tendons 26 are tensioned and anchored to the outside of the precast columns 1 or the bottom of the inclined ladder beam 23 through the anchor 6.

[0022] See Figure 3 The trapezoidal wing shear wall 24 is trapezoidal in shape, with a thickness equal to the width of the inclined ladder beam 23. The vertical reinforcing bars of the trapezoidal wing shear wall 24 extend from inside the inclined ladder beam 23, and the bottom inclined design angle of the trapezoidal wing shear wall 24 is consistent with the design angle of the stair section 21. The unbonded prestressing tendons 26 inside the trapezoidal wing shear wall 24 are pre-embedded in it before the concrete is poured in the precast concrete of the trapezoidal wing shear wall 24 PC factory. The pre-embedding position of the unbonded prestressing tendons 26 should take into account the position of the reserved holes on the precast column 1, and the outward extension length of the unbonded prestressing tendons should meet the requirements of hoisting, tensioning after positioning, and anchoring processes. The vertical sides of the trapezoidal wing shear wall 24 in the post-cast section 4 are roughened or keyways are set, and the roughness is not less than 85%.

[0023] At the connection point between the precast column 1 and the trapezoidal wing shear wall 24, a post-cast section 4 is provided. Near the post-cast section 4, the precast column 1 has embedded tie bars. These tie bars are accurately embedded during the precast column 1 PC manufacturing process. The diameter of the embedded tie bars is not less than 8mm and not less than the diameter of the horizontally distributed reinforcing bars inside the trapezoidal wing shear wall 24. The length of the embedded tie bars is not less than 300mm, and the ends are provided with 180-degree hooks. To facilitate the tensioning and anchoring of the unbonded prestressing tendons 26 after they pass through the post-cast section 4 and the precast column 1, a pre-drilled hole is provided inside the precast column 1. The unbonded prestressing tendons 26 pass through this pre-drilled hole and are anchored to the side of the precast column 1. The diameter of the pre-drilled hole is 2mm to 3mm larger than the outer diameter of the unbonded prestressing tendons 26. The position of the pre-drilled hole in the column corresponds one-to-one with the position of the integrally formed unbonded prestressing tendons 26 inside the trapezoidal wing shear wall 24, and the installation error must not exceed 2mm.

[0024] See Figure 4 and Figure 5The double-wing integrated staircase 2 is anchored one by one into the upper part of the truss reinforcement in the composite slab 31 by the outward-extending steel bars and anchor plates 7 provided at the transverse ladder beam 22. It adopts a double-row outward-extending steel bar design, and each outward-extending steel bar is provided with an anchor plate 7 at the end to enhance the coordinated seismic resistance of the double-wing integrated staircase 2 and the main prefabricated frame structure. The length of the outward-extending steel bar is not less than 600mm. The outward-extending steel bar is designed to be bent out of the transverse ladder beam 22 after the longitudinal steel bar of the stair section 21. The lower row of outward-extending steel bars rests on the top of the truss reinforcement of the composite slab 31 and is fixed to the truss reinforcement by spot welding.

[0025] The transverse ladder beam 22 is provided with support holes 27. The pre-embedded steel rods 32 on the composite slab 31 are inserted into the support holes 27 when the double-wing integrated staircase 2 is hoisted and positioned. The diameter of the support holes 27 is not less than 80mm, and the diameter of the pre-embedded steel rods 32 is not less than 40mm. An anchor plate 7 is also provided on the top of the pre-embedded steel rods 32. The top surface elevation of the anchor plate 7 is 3mm~5mm lower than the top surface elevation of the transverse ladder beam 22. High-strength grouting material is injected into the cavity between the pre-embedded steel rods 32 and the support holes 27. The high-strength grouting material is micro-expansion low-shrinkage sulfur mortar grouting material.

[0026] When the bottom unbonded prestressing tendon 26 is prefabricated in the prefabricated PC factory to produce the double-wing integrated staircase 2, the design scheme of "pre-embedded and transverse through the trapezoidal wing shear wall + inclined stair beam integrated molding" is adopted. That is, the bottom unbonded prestressing tendon 26 is not only partially embedded inside the trapezoidal wing shear wall 24, but also partially embedded inside the inclined stair beam 23. One end of this unbonded prestressing tendon 26 is anchored to the side of the prefabricated column 1, and the other end is anchored to the bottom of the inclined stair beam 23.

[0027] This invention provides a construction method for a prefabricated seismic-resistant staircase structure to achieve the aforementioned prefabricated seismic-resistant staircase structure. (See reference...) Figure 6 The overall construction process is as follows: Step S1: Prefabricate the double-wing integrated staircase in advance and hoist the various components of the frame structure; Step S2: Verify the positional relationship of the pre-embedded steel bars, and hoist the double-wing plate integrated staircase into place; Step S3: Tighten the anchor plate inside the support hole and fill the hole with high-strength grout; Step S4: Tighten the transverse ladder beam end overhanging reinforcement and its end anchor plate, and pour the composite slab concrete; Step S5: Drilling and positioning of unbonded prestressed tendons, and connecting the transverse distributed steel bars of the trapezoidal wing shear wall and the pre-embedded tie bars of the precast columns; Step S6: Post-cast concrete pouring and curing, tensioning and anchoring of unbonded prestressed tendons.

[0028] The above construction method generally follows the technical solution of "integrated double-wing staircase seismic design, trapezoidal wing shear wall and precast column post-cast joint reinforcement to enhance the load-bearing capacity, anchor plates for all extended steel bars at the ends of the transverse stair beams, pre-embedded tie bars in the precast column body to connect with the transverse distributed steel bars of the T-beam wing plate to form post-cast joints, integrated unbonded prestressed tendons for molding, perforation, tensioning and anchoring, the lowest unbonded prestressed tendons spanning the trapezoidal wing shear wall and the inclined stair beams, and the connection nodes of the transverse stair beams and composite slabs using pre-embedded steel bars in the support holes with added anchor plates, and high-strength grouting sealing process, thereby constructing a seismic system for the integrated double-wing staircase and the main structure." The specific construction process details are as follows: Step S1: Prefabrication of the double-wing integrated staircase; hoisting of various components of the frame structure: According to the technical plan, the double-wing integrated staircase is prefabricated in a prefabricated PC factory. Specialized molds are used to cast the staircase sections, transverse beams, inclined beams, trapezoidal wing shear walls, and unbonded prestressed tendons into a single, integrated concrete structure, without any construction joints. The reinforcing bars at the corners of the inclined beams and trapezoidal wing shear walls are bent 90 degrees from the inside of the inclined beams and extend into the trapezoidal wing shear wall mold, forming an integrated beam-slab node. The left and right ends of the trapezoidal wing shear wall are 300mm from the corresponding transverse beam edges, and the outwardly extending transverse reinforcing bars at both ends of the trapezoidal wing shear wall must meet design requirements. After the prefabrication of the double-wing integrated staircase, demolding, hoisting, transportation, and stacking can only proceed after the concrete strength reaches 100% of the design strength. During this process, special attention should be paid to protecting the finished double-wing integrated staircase, especially the staircase sections, the corners of the trapezoidal wing shear walls, the transverse reinforcing bars extending outwards at both ends of the trapezoidal wing shear walls, the outward-extending reinforcing bars at the ends of the transverse stair beams, and the anchor plates at the ends of the outward-extending reinforcing bars. Simultaneously with the prefabrication of the double-wing integrated staircase, the main frame structure of the prefabricated building should be hoisted and constructed to provide an effective working surface for the overall hoisting and positioning of the double-wing integrated staircase. For the prefabricated columns in the prefabricated building frame structure, it must be ensured that the reserved holes and embedded tie bars in the column body meet the design requirements and are protected. Before the double-wing integrated staircase is hoisted and positioned, the reserved holes in the prefabricated column body should be sealed with special rubber plugs to avoid affecting the subsequent drilling of unbonded prestressed tendons. Process acceptance and recording should be carried out.

[0029] Step S2: Verify the positional relationship of the pre-embedded steel bars, and hoist the integrated double-wing staircase into place: According to the technical plan, once the integrated double-wing staircase is transported to the site and all prefabricated components of the prefabricated building's main frame are hoisted, the staircase can be hoisted and positioned. Before hoisting the integrated double-wing staircase, the positional relationship and outward extension length of the embedded steel bars at the upper and lower end composite slabs of the staircase should be accurately checked to ensure that the error is controllable before proceeding with the hoisting operation. During the hoisting process, the staircase should be positioned slowly, accurately aligning the embedded steel bars on the composite slabs with the support holes in the transverse ladder beams at the upper and lower ends of the staircase. Repeated checks and adjustments should be made, and process acceptance and records should be maintained.

[0030] Step S3: Tighten the anchor plate inside the support hole, and fill the hole with high-strength grout. According to the technical plan, after the double-wing integrated staircase is hoisted into place, a high-pressure air gun is used to clean the cavity between the support holes and the embedded steel bars on the transverse stair beams. At the same time, in order to enhance the integrity between the double-wing integrated staircase and the composite slabs (floor slabs and rest platforms) in the main frame structure, anchor plates are tightened one by one onto the top of the embedded steel bars to ensure that the top elevation of the anchor plates meets the requirements after tightening. Then, high-strength grouting material is filled into the cavity between the support holes and the embedded steel bars on the double-wing integrated staircase that has been installed. The high-strength grouting material should fill the entire cavity between the support holes and the embedded steel bars and cover the top surface of the anchor plates. The concealed works acceptance and recording are carried out.

[0031] Step S4: Tighten the transverse ladder beam end overhanging reinforcement and its end anchor plate, and pour the composite slab concrete: According to the technical plan, after the high-strength grouting material reaches its initial setting strength, the protruding reinforcing bars at the transverse stair beams and their end anchor plates will be adjusted before the concrete pouring of the upper part of the composite slab. This ensures that 100% of the protruding reinforcing bars at the transverse stair beams have anchor plates tightened at their ends. It is important to note that the anchor plates at the ends of the protruding reinforcing bars at the transverse stair beam ends and the anchor plates inside the support holes of the transverse stair beams are not the same component. The protruding reinforcing bars and anchor plates will be poured into the composite section of the upper part of the composite slab in one go to further strengthen the integrity between the integrated double-wing staircase and the main frame structure. The concrete strength of the composite slab should not be lower than C35 and should be one grade higher than the concrete strength of the integrated double-wing staircase. Concealed works acceptance and recording should be properly carried out.

[0032] Step S5: Drilling and positioning of unbonded prestressing tendons; connection of transverse reinforcing bars in trapezoidal wing shear wall and pre-embedded tie bars in precast columns: According to the technical plan, after the composite slab concrete is poured, the transversely distributed steel bars extending from the left and right ends of the trapezoidal wing shear wall are welded to the pre-embedded tie bars of the precast column body. The special rubber plugs in the reserved holes inside the precast column body are pulled out, and the unbonded prestressed tendons extending from the left and right ends of the trapezoidal wing shear wall are passed through the reserved holes inside the precast column. The unbonded prestressed tendons are temporarily fixed with anchors, and the concealed works are inspected and recorded.

[0033] Step S6: Post-cast concrete pouring and curing, tensioning and anchoring of unbonded prestressed tendons: According to the technical plan, after the steel reinforcement connection and unbonded prestressing tendon perforation and positioning in the post-cast section, the bottom of the post-cast section between the precast column and the trapezoidal wing shear wall is cleaned with a high-pressure air gun, and aluminum formwork is used to support the post-cast section. Then, fine stone concrete of not less than C35 is used to pour the post-cast section in one go without leaving construction joints. The concrete pouring in the post-cast section is treated with low shrinkage and micro-expansion fine stone concrete and is strengthened for curing. Once the concrete strength of the post-cast section reaches 100% of the design strength, the unbonded prestressing tendons can be tensioned and anchored. The on-site tensioning of the unbonded prestressing tendons adopts the following method: "starting with the prestressing tendons at the top of the trapezoidal wing shear wall, tensioning one by one from top to bottom, symmetrical tensioning, anchoring as tensioning progresses, and finally tensioning the unbonded prestressing tendons that traverse the inclined ladder beam and the interior of the trapezoidal wing shear wall." Due to the limitations of the on-site work surface and construction environment, the tensioning of the unbonded prestressing tendons that traverse the inclined ladder beam and the interior of the trapezoidal wing shear wall involves first anchoring the end of the unbonded prestressing tendon at the bottom of the inclined ladder beam, and then using a one-end tensioning method to anchor the unbonded prestressing tendon to the side of the precast column. Finally, all anchorages are sealed with high-strength sulfur mortar. Since the area above the top surface of the trapezoidal wing shear wall is a non-load-bearing wall, and the top surface of the trapezoidal wing shear wall is designed to be horizontal, the masonry can be directly constructed from the top surface of the trapezoidal wing shear wall, and process acceptance and recording should be carried out.

[0034] In summary, this invention integrates the prefabrication of stair sections, transverse stair beams, diagonal stair beams, and trapezoidal wing shear walls, and combines these with unbonded prestressed tendons, post-cast joint connections, outward reinforcement anchorage, and high-strength grouting construction techniques to create an effective collaborative force-bearing system between the prefabricated staircase and the main structure. Without altering the basic form of existing prefabricated frames, it enhances the overall integrity, stability, and resilience of the staircase under seismic loads, while also improving the controllability of joint construction quality and the inspectability of concealed works.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A prefabricated staircase earthquake-resistant structure, characterized in that, The staircase includes precast columns, composite slabs, and a double-wing plate integrated staircase between the precast columns, wherein the precast columns are provided with embedded tie rods and reserved holes; The double-wing plate integrated staircase is prefabricated as a whole in the prefabricated PC factory, including stair sections, horizontal ladder beams, inclined ladder beams, trapezoidal wing plate shear walls and unbonded prestressed tendons. The horizontal ladder beams are located at the upper and lower ends of the stair sections, and the extended steel bars of the horizontal ladder beams are provided with anchor plates for connecting with the truss bars of the composite plate. The inclined stair beams are located on the left and right sides of the stair section, and the trapezoidal wing shear wall is located on the upper side of the inclined stair beams. The trapezoidal wing shear wall has transversely distributed reinforcing bars extending outward on both sides, and its top surface is horizontal and has masonry. A post-cast section is provided between the trapezoidal wing shear wall and the adjacent precast column, and the embedded tie bars are connected to the transversely distributed reinforcing bars of the trapezoidal wing shear wall in the post-cast section. The unbonded prestressed tendons are inserted through the trapezoidal wing shear wall, the post-cast section, and the reserved holes, and are tensioned and anchored to the outside of the precast column or the bottom of the inclined ladder beam by anchors.

2. The prefabricated staircase seismic-resistant structure according to claim 1, characterized in that, The trapezoidal wing shear wall has a trapezoidal cross-section, and its thickness is equal to the width of the inclined ladder beam. The vertical distributed reinforcement of the trapezoidal wing shear wall extends from the inside of the inclined ladder beam. The bottom inclined design angle of the trapezoidal wing shear wall is consistent with the design angle of the stair section. The vertical side of the trapezoidal wing shear wall in the post-cast section is roughened or keyways are set, and the roughness is not less than 85%.

3. The prefabricated staircase seismic-resistant structure according to claim 1, characterized in that, The diameter of the embedded tie bar shall not be less than 8mm and not less than the diameter of the horizontally distributed steel bars inside the trapezoidal wing shear wall. The length of the embedded tie bar shall not be less than 300mm, and the end shall be provided with a 180-degree hook. The unbonded prestressed tendon shall be anchored to the side of the precast column after passing through the reserved hole. The diameter of the reserved hole shall be 2mm to 3mm larger than the outer diameter of the unbonded prestressed tendon. The position of the reserved hole shall correspond one-to-one with the position of the unbonded prestressed tendon inside the trapezoidal wing shear wall, and the installation error shall not exceed 2mm.

4. The prefabricated staircase seismic-resistant structure according to claim 1, characterized in that, The extended reinforcing bars of the transverse ladder beam are achieved by bending the longitudinal reinforcing bars of the stair section and extending them out of the transverse ladder beam, and a double-row design is adopted; the length of the extended reinforcing bars is not less than 600mm, and the lower row of extended reinforcing bars rests on the top of the composite slab truss reinforcement and is fixed to the truss reinforcement by spot welding.

5. The prefabricated staircase seismic-resistant structure according to claim 1, characterized in that, The transverse ladder beam is provided with support holes, and the upper side of the composite plate is provided with a pre-embedded steel bar inserted into the support hole. The diameter of the support hole is not less than 80mm, and the diameter of the pre-embedded steel bar is not less than 40mm. An anchor plate is provided on the top of the pre-embedded steel bar. The top surface elevation of the anchor plate is 3mm~5mm lower than the top surface elevation of the transverse ladder beam. High-strength grout is injected into the cavity between the pre-embedded steel bar and the support hole. The high-strength grout is a micro-expansion low-shrinkage sulfur mortar grout.

6. The prefabricated staircase seismic-resistant structure according to claim 1, characterized in that, The bottommost unbonded prestressing tendon is partly inside the trapezoidal wing shear wall and partly embedded inside the inclined ladder beam. One end of this unbonded prestressing tendon is anchored to the side of the precast column and the other end is anchored to the bottom of the inclined ladder beam.

7. A construction method for a prefabricated staircase seismic-resistant structure, characterized in that, The overall construction process is as follows: Step S1: Prefabricate the double-wing integrated staircase in advance and hoist the various components of the frame structure; Step S2: Verify the positional relationship of the pre-embedded steel bars, and hoist the double-wing plate integrated staircase into place; Step S3: Tighten the anchor plate inside the support hole and fill the hole with high-strength grout; Step S4: Tighten the transverse ladder beam end overhanging reinforcement and its end anchor plate, and pour the composite slab concrete; Step S5: Drilling and positioning of unbonded prestressed tendons, and connecting the transverse distributed steel bars of the trapezoidal wing shear wall and the pre-embedded tie bars of the precast columns; Step S6: Post-cast concrete pouring and curing, tensioning and anchoring of unbonded prestressed tendons.

8. A construction method for a prefabricated staircase seismic-resistant structure, characterized in that, The detailed construction process is as follows: Step S1: Prefabrication of the double-wing integrated staircase; hoisting of various components of the frame structure: The double-wing integrated staircase is prefabricated in a prefabricated PC factory. Using matching molds, the staircase sections, transverse stair beams, inclined stair beams, trapezoidal wing shear walls, and unbonded prestressed tendons are cast in one piece, completing the process in one go without construction joints. The reinforcing bars at the corners of the inclined stair beams and trapezoidal wing shear walls are bent 90 degrees from the inside of the inclined stair beams and extend into the interior of the trapezoidal wing shear wall mold, forming an integrated beam-slab node. The left and right ends of the trapezoidal wing shear wall are 300mm from the corresponding transverse stair beam edges, and their extended transverse reinforcing bars meet design requirements. Requirements: Demolding, hoisting, transportation, and stacking of concrete after it reaches 100% of the design strength; during the process, finished product protection shall be provided for the stair sections, corners of trapezoidal wing shear walls, extended transverse distributed reinforcement, extended reinforcement at the ends of transverse stair beams, and their end anchor plates; the prefabricated building main frame structure shall be hoisted simultaneously to provide a working surface for the overall hoisting of the staircase; the reserved holes and embedded tie bars of the precast columns shall meet the design requirements and be protected; the reserved holes shall be sealed with special rubber plugs before hoisting to avoid affecting the subsequent perforation of unbonded prestressed tendons; Step S2: Verify the positional relationship of the pre-embedded steel bars, and hoist the integrated double-wing staircase into place: After the double-wing integrated staircase is delivered to the site and all prefabricated components of the main frame are hoisted, the positional relationship and outward extension length of the embedded steel bars at the upper and lower ends of the staircase are checked, and hoisting is carried out under controllable error conditions. During the hoisting process, the staircase is slowly positioned to ensure that the embedded steel bars on the composite slab are accurately aligned with the support holes in the transverse ladder beams at the upper and lower ends of the staircase, and the position is repeatedly checked and adjusted. Step S3: Tighten the anchor plate inside the support hole, and fill the hole with high-strength grout. After the double-wing integrated staircase is in place, a high-pressure air gun is used to clean the cavity between the support hole of the horizontal stair beam and the pre-embedded steel bar; the anchor plate is screwed onto the top of the pre-embedded steel bar one by one to ensure that the top elevation meets the requirements; then high-strength grouting material is filled into the cavity between the support hole and the pre-embedded steel bar, and the grouting material fills the cavity and covers the top surface of the anchor plate. Step S4: Tighten the transverse ladder beam end overhanging reinforcement and its end anchor plate, and pour the composite slab concrete: After the high-strength grout reaches its initial setting strength, adjust the extended steel bars at the ends of the transverse ladder beams and their end anchor plates, and then pour the upper concrete of the composite slab. Ensure that each extended steel bar is fitted with an anchor plate. The end anchor plates of the extended steel bars at the ends of the transverse ladder beams and the anchor plates in the support holes are different components. The extended steel bars and anchor plates are poured together in the upper composite layer of the composite slab. The concrete strength of the composite slab is not lower than C35 and is one grade higher than the concrete strength of the double-wing integrated staircase. Step S5: Drilling and positioning of unbonded prestressing tendons; connection of transverse reinforcing bars in trapezoidal wing shear wall and pre-embedded tie bars in precast columns: After the composite slab concrete is poured, the transverse distributed steel bars extending outward at both ends of the trapezoidal wing plate shear wall are welded to the pre-embedded tie bars in the precast column body; the special rubber plugs in the precast column reserved holes are pulled out, and the unbonded prestressed tendons extending outward at both ends of the trapezoidal wing plate shear wall are passed through the precast column reserved holes and temporarily fixed with anchors. Step S6: Post-cast concrete pouring and curing, tensioning and anchoring of unbonded prestressed tendons: After the reinforcement connections and unbonded prestressing tendon insertion holes in the post-cast section are in place, a high-pressure air gun is used to clean the bottom of the post-cast section between the precast column and the trapezoidal wing shear wall. Aluminum formwork is used for support, and low-shrinkage, micro-expansion fine aggregate concrete of not less than C35 is poured in one go without leaving construction joints, and curing is strengthened. After the concrete strength of the post-cast section reaches 100% of the design strength, the unbonded prestressing tendons are tensioned and anchored. The tensioning sequence is to start from the top of the trapezoidal wing shear wall, tensioning one by one from top to bottom, symmetrically, and anchoring as tensioning, and finally tensioning the unbonded prestressing tendons that pass through the inclined ladder beam and inside the trapezoidal wing shear wall. Due to the limited working space, the prestressing tendons in this part are first anchored to the bottom end of the inclined ladder beam, and then anchored to the side of the precast column by tensioning one end. All anchorages are sealed with sulfur mortar high-strength grout. The top surface of the trapezoidal wing shear wall is a horizontal plane, and non-load-bearing walls are directly built on it.

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