Construction method of fabricated building

Abstract

This invention discloses a construction method for prefabricated buildings, relating to the field of prefabricated building construction technology. By reserving and constructing functionally differentiated connection structures at the high, low, and side ends of the cast-in-place main structure and the prefabricated staircase—namely, a high-end fixed hinge support structure within the first anchorage gap, a low-end sliding hinge support structure within the second anchorage gap, a lateral connection structure at the installation groove and connection position, and a gap-filling structure within the filling gap—a prefabricated staircase-main structure connection system is systematically constructed that can both transmit bending moment and shear force and coordinate deformation. This avoids the drawbacks of existing technologies, such as limited space for on-site grouting operations, stringent requirements for the precision of rebar hole alignment, and unclear force transmission paths at nodes, significantly improving construction efficiency and installation error tolerance, while ensuring the integrity and safety of the structure under loads such as earthquakes.

Description

Technical Field

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

[0002] As a crucial component of building structures, prefabricated staircase construction is a key step in improving project efficiency, reducing on-site wet work, and minimizing formwork support consumption. In the early stages of this technology's development, the installation of prefabricated staircases primarily focused on the ease of hoisting and temporary fixing, with connection nodes often employing simple grouting or partial welding. However, with the increase in high-rise and super high-rise buildings and increasingly stringent requirements for overall structural seismic performance, the connection technology between prefabricated staircases and the main structure has evolved from simple support to rigid or semi-rigid connections capable of transferring horizontal loads and participating in the overall structural stress distribution. This aims to address the reliable force transmission and deformation coordination issues between prefabricated components and the cast-in-place main structure (especially cast-in-place load-bearing beams and cast-in-place reinforced concrete shear walls).

[0003] Currently, in conventional prefabricated construction involving the connection of precast stairs with cast-in-place load-bearing beams and cast-in-place shear walls, the common practice is to use anchored reinforcement connection: pre-embed steel bar connecting sleeves or reserve bar insertion holes in the cast-in-place load-bearing beams or shear walls. After the precast stairs are hoisted into place, grout is injected to connect the reserved steel bars at the ends of the precast stairs with the cast-in-place structure as one unit, attempting to form a node with a certain bending moment transmission capacity.

[0004] However, in practical engineering applications and structural stress analysis, although the above-mentioned existing technical solutions improve the stiffness of anchorage-reinforced connections, the space for on-site grouting operations is small, the density is difficult to detect, the node structure is complex, the prefabrication accuracy requirements are extremely high, and even a small installation deviation may cause the reinforcing bars to not be aligned with the holes, which seriously affects the construction efficiency. Summary of the Invention

[0005] The main objective of this invention is to propose a construction method for prefabricated buildings, aiming to solve the technical problems of existing technologies for anchored and reinforced connections. Although these technologies improve rigidity, they suffer from limited space for on-site grouting, difficulty in detecting density, complex node structures, extremely high prefabrication precision requirements, and the fact that even slight installation deviations can lead to misalignment of reinforcing bars with holes, severely impacting construction efficiency.

[0006] To achieve the above objectives, in a first aspect, the present invention proposes a construction method for prefabricated buildings, comprising the following steps: In the pre-designed construction area, reinforced concrete pouring is carried out to form load-bearing beam layers that are spaced apart on both sides along the height direction and cast-in-place reinforced concrete shear walls surrounding the two load-bearing beam layers; wherein, connection positions are formed in the cast-in-place reinforced concrete shear walls. When both load-bearing beam layers and the cast-in-place reinforced concrete shear wall reach the preset strength, the prefabricated staircase is hoisted and its high and low ends are respectively placed on the two load-bearing beam layers; wherein, a first anchoring gap is formed between the high end and the corresponding load-bearing beam layer, and a second anchoring gap is formed between the low end and the corresponding load-bearing beam layer, one side of the prefabricated staircase is located close to the cast-in-place reinforced concrete shear wall and a filling gap is formed between the prefabricated staircase and the cast-in-place reinforced concrete shear wall, and an installation groove is formed in the area of ​​the prefabricated staircase corresponding to the connection position, and the installation groove is located on the stair surface of the prefabricated staircase; A high-end fixed hinge support structure is constructed and filled within the first anchoring gap. A low-end sliding hinge support structure is constructed and filled within the second anchoring gap. A lateral connection structure is provided at the mounting slot and the connection location; A gap-filling structure is constructed in the gap to connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall, thereby creating the prefabricated building.

[0007] In one embodiment, the step of pouring reinforced concrete in a predetermined construction area to form load-bearing beam layers spaced apart along the height direction on both sides and cast-in-place reinforced concrete shear walls surrounding the two load-bearing beam layers includes: In the pre-designed construction area, steel reinforcement binding operations are carried out to form a first steel reinforcement cage for constructing the two layers of the load-bearing beams and a second steel reinforcement cage for the cast-in-place reinforced concrete shear wall. A welding anchoring mechanism is pre-embedded in the second reinforcing cage; wherein the welding anchoring mechanism connects a connecting screw and an anchor plate, the connecting screw is welded to the main reinforcement bar in the second reinforcing cage, the connecting screw extends out of the second reinforcing cage along the thickness direction of the second reinforcing cage toward the first reinforcing cage and connects with the anchor plate, the anchor plate is exposed outside the second reinforcing cage, and the location of the anchor plate forms the connection position; Formwork is erected around the outer periphery of the first and second reinforcing cages; wherein, the side of the anchor plate facing the first reinforcing cage is exposed on the formwork. The concrete is poured in place to form the two layers of the load-bearing beams and the cast-in-place reinforced concrete shear wall.

[0008] In one embodiment, each of the load-bearing beam layers has an anchorage position at its top, and a pre-embedded anchor bolt is provided at the anchorage position; The step of filling the first anchorage gap with a high-end fixed hinge support structure includes: A conical hole is reserved at the high end of the prefabricated staircase; wherein the taper of the conical hole faces the bottom surface of the prefabricated staircase. The pre-embedded anchor bolts are passed through the conical holes and initially tightened on the top surface of the prefabricated staircase using nuts and washers; The inner wall of the conical hole is moistened before injection; High-strength, non-shrink grout is continuously injected to a level slightly higher than the conical opening, and then troweled; wherein the strength grade of the high-strength, non-shrink grout is C, and C≥C40.

[0009] In one embodiment, prior to the step of filling the second anchorage gap with the low-end sliding hinge support structure, the method further includes: Clean the base surface at the anchorage position corresponding to the lower end so that the lower end can overlap and cover the corresponding anchorage position.

[0010] In one embodiment, the step of filling the second anchorage gap with the low-end sliding hinge support structure includes: A graphite composite slip layer is laid between the anchoring position corresponding to the lower end and the lower end; wherein the graphite composite slip layer is composed of a lower layer of roofing felt, a middle graphite layer and an upper layer of roofing felt, and the coefficient of friction of the graphite composite slip layer is less than 0.1; The pre-embedded anchor bolts are passed through the straight holes or cavities reserved at the bottom of the prefabricated staircase, locked with double nuts, and a preset number of fasteners is reserved to form a vertical micro-movement gap, so that the prefabricated staircase can slide in a controlled manner along the longitudinal direction of the load-bearing beam to form the sliding hinge support structure; wherein, the preset number of fasteners is A, 1 fastener ≤ A ≤ 2 fasteners, and the vertical micro-movement gap is B, 1 mm ≤ B ≤ 2 mm.

[0011] In one embodiment, the step of performing a lateral connection structure at the mounting slot and the connection location includes: A first connecting mechanism is constructed within the mounting groove; wherein the first connecting mechanism includes an angle steel, a pre-embedded component, and a filler. The angle steel is installed within the mounting groove, and one side of the angle steel extends outward from the mounting groove along the width direction of the prefabricated staircase to form a welding position. A vertically arranged through hole is formed on the side of the angle steel located within the mounting groove. The through hole corresponds to a pre-embedded hole preset at the bottom of the mounting groove. The pre-embedded component passes vertically through the through hole and extends into the corresponding pre-embedded hole to anchor the angle steel to the staircase body. The filler fills the mounting groove to pre-embed the angle steel within the mounting groove. Weld the angle steel to the anchor plate; Mortar is poured into the top of the angle steel to form the lateral connection structure.

[0012] In one embodiment, the step of performing the first connecting mechanism within the mounting slot includes: The angle steel is anchored in the mounting groove using a pre-embedded component; wherein the pre-embedded component includes an adhesive block and a pre-embedded screw, the adhesive block is filled in the pre-embedded hole, and the pre-embedded screw passes through the through hole and is inserted into the adhesive block to anchor the angle steel to the ladder body.

[0013] In one embodiment, the step of constructing a gap-filling structure in the gap and connecting the prefabricated staircase to the cast-in-place reinforced concrete shear wall to form the prefabricated building includes: Fireproof rock wool board is filled into the filling gap; wherein, a bonding cavity is formed at each end of the fireproof rock wool board along its height direction; The two bonding cavities are filled with bonding material to form the gap filling structure and to connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall to form the prefabricated building.

[0014] In one embodiment, the step of filling the two bonding cavities with bonding material to form the gap-filling structure and connecting the prefabricated staircase with the cast-in-place reinforced concrete shear wall to manufacture the prefabricated building includes: PE rods and structural sealant are sequentially filled into the two bonding cavities to form the gap filling structure and connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall to form the prefabricated building.

[0015] In one embodiment, the placement lengths of both the high-end and low-end ends are not less than the minimum placement length required by the seismic fortification intensity.

[0016] The technical solution of this invention systematically constructs a connection system between the precast staircase and the main structure that can both transmit bending moment and shear force and coordinate deformation by reserving and constructing functionally differentiated connection structures at the high end, low end, and sides of the cast-in-place main structure and the precast staircase. This system includes a high-end fixed hinge support structure within the first anchorage gap, a low-end sliding hinge support structure within the second anchorage gap, a lateral connection structure at the installation groove and connection position, and a gap-filling structure within the filling gap. This avoids the drawbacks of existing technologies, such as limited space for on-site grouting operations, stringent requirements for the precision of rebar hole alignment, and unclear force transmission paths at nodes. It significantly improves construction efficiency and installation tolerance while ensuring the integrity and safety of the structure under loads such as earthquakes. Attached Figure Description

[0017] 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.

[0018] Figure 1 A flowchart of the construction method for prefabricated buildings provided by the present invention.

[0019] 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

[0020] 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.

[0021] 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.

[0022] 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.

[0023] This invention proposes a construction method for prefabricated buildings.

[0024] Please see Figure 1 To facilitate understanding, this construction method for prefabricated buildings includes the following steps: S100. In the pre-designed construction area, reinforced concrete pouring is carried out to form load-bearing beam layers distributed at intervals along the height direction on both sides and cast-in-place reinforced concrete shear walls surrounding the two load-bearing beam layers; wherein, connection positions are formed in the cast-in-place reinforced concrete shear walls.

[0025] Specifically, in this embodiment, the construction area is first surveyed and marked out according to the building structure drawings to determine the pouring range of the load-bearing beam layers and the cast-in-place reinforced concrete shear walls. The load-bearing beam layers referred to in this step are reinforced concrete structures that extend horizontally at different floor levels of the building and are used to bear the loads of floor slabs, stairs, and other components. By setting up formwork, tying the reinforcing steel frame, and pouring concrete either integrally or in batches, upper and lower load-bearing beam layers are formed, spaced apart along the building's height, along with a cast-in-place reinforced concrete shear wall that surrounds and connects these two load-bearing beam layers.

[0026] It is important to clarify that, in this embodiment, the connection points formed on the cast-in-place reinforced concrete shear wall refer to the pre-tying or welding of exposed connecting steel reinforcement components at corresponding positions on the shear wall reinforcement skeleton before the shear wall concrete is poured, based on the lateral connection requirements of the precast staircase. Alternatively, it can be steel reinforcement connection base points formed at a predetermined elevation of the shear wall through post-reinforcement technology after the concrete is poured and the formwork is removed. The function of these connection points is to provide a reliable physical interface for anchoring and force transmission between the subsequent lateral connection structure and the main structure, ensuring that effective lateral restraint can be established between the precast staircase and the shear wall, thereby solving the problem of lateral instability or incoordination with the deformation of the main structure that may occur under earthquakes or other horizontal loads.

[0027] S200. When the two load-bearing beam layers and the cast-in-place reinforced concrete shear wall have reached the preset strength, the prefabricated staircase is hoisted and its high end and low end are respectively placed on the two load-bearing beam layers; wherein, a first anchoring gap is formed between the high end and the corresponding load-bearing beam layer, and a second anchoring gap is formed between the low end and the corresponding load-bearing beam layer, one side of the prefabricated staircase is located close to the cast-in-place reinforced concrete shear wall and a filling gap is formed between the prefabricated staircase and the cast-in-place reinforced concrete shear wall, and an installation groove is formed in the area of ​​the prefabricated staircase corresponding to the connection position, and the installation groove is located on the stair surface of the prefabricated staircase.

[0028] Specifically, in this step, the precast staircase can only be hoisted after the concrete of the two load-bearing beam layers and the cast-in-place reinforced concrete shear wall, which are poured on-site, has cured to the preset strength required by the structural design. This preset strength usually refers to the concrete compressive strength reaching more than 75% of the design value, to ensure that the load-bearing base does not suffer localized compressive failure or structural damage when bearing the self-weight of the precast staircase and construction loads.

[0029] During the installation of prefabricated stairs, lifting equipment is used to lift the prefabricated stairs, which have been manufactured to precise dimensions in the factory, to the installation floor. By adjusting the lifting equipment and traction ropes, the spatial posture of the prefabricated stairs is made to meet the installation requirements. Finally, the upper end is stably erected on the predetermined cantilever or corbel support of the upper load-bearing beam, and the lower end is stably erected on the corresponding support or leveling layer of the lower load-bearing beam.

[0030] S300. Fill the first anchorage gap with a high-end fixed hinge support structure.

[0031] Specifically, in this step, after the high and low ends of the precast staircase are accurately positioned and temporarily fixed, the perimeter of the first anchoring gap is first sealed. This is typically done by creating a cofferdam using quick-setting cement mortar or specialized sealing materials to prevent the subsequent grout from leaking out. Then, high-strength, non-shrink grout or epoxy resin mortar, mixed according to precise proportions, is filled into the internal cavity of the first anchoring gap using pressure grouting or gravity injection until the entire gap is filled and in close contact with the surrounding structure.

[0032] The high-end fixed hinge support structure formed by the filling construction has the following main working mechanism: the hardened anchoring material firmly bonds and locks the end of the precast staircase's high end to the upper load-bearing beam layer into a whole. This structure can effectively restrain the displacement of the precast staircase's high end in the vertical, horizontal, and rotational directions, making it a fixed support node capable of transmitting vertical shear force, horizontal axial force, and in-plane bending moment. This construction measure directly solves the technical problems of existing simply supported structures being unable to transmit bending moment and having poor overall integrity, significantly improving the collaborative working ability of the staircase and the main structure under seismic loading, and enhancing the staircase's contribution as an inclined support component to the overall structural stiffness.

[0033] S400, Fill the second anchoring gap with a low-end sliding hinge support structure.

[0034] Specifically, in this step, the construction process for the lower-end second anchorage gap differs from that of the higher-end gap. Firstly, the filling material is not typically the same high-strength adhesive material used for the higher-end gap; instead, a structure with a specific lubrication or isolation layer may be chosen. For example, a layer of asphalt felt, PTFE board, or graphite powder lubrication layer is first laid on the lower support surface of the precast staircase or the bearing surface of the load-bearing beam within the second anchorage gap, and then the remaining gaps are filled with high-strength mortar, ensuring only vertical bearing capacity and horizontal restraint.

[0035] The core function of the low-end sliding hinge support structure formed by the filling construction is as follows: Under normal working conditions, the support can reliably withstand the vertical pressure transmitted from the precast staircase and limit its lateral displacement or overturning. When the main structure experiences inter-story displacement due to temperature changes, concrete shrinkage and creep, or seismic forces, the support structure allows the low end of the precast staircase to slide horizontally with a limited amplitude along the span of the stair slab. This sliding capability effectively releases the axial constraint force within the stair slab, avoiding stair slab cracking, crushing, or shear failure at the support due to forced deformation. It achieves deformation coordination between the precast staircase and the main frame structure, thereby solving the technical problem of secondary internal forces and damage easily generated during structural deformation in existing rigid connection schemes.

[0036] S500, A lateral connection structure is provided at the mounting slot and the connection position.

[0037] Specifically, in this step, the construction of the lateral connection structure is crucial for establishing a reliable force transmission path between the precast staircase and the cast-in-place reinforced concrete shear wall. During operation, construction workers can use the installation grooves on the precast staircase surface as their working space. First, clean the loose dust and debris from the installation grooves and check the condition of the exposed reinforcing bars or embedded parts at the corresponding connection positions on the cast-in-place reinforced concrete shear wall.

[0038] Next, the lateral connection structure is installed. A typical construction method is as follows: one end of the prefabricated L-shaped or flat steel connector is inserted into the installation groove and welded or bolted to the anchoring steel bars or embedded parts reserved in the prefabricated staircase; the other end of the connector is welded to the connection position on the cast-in-place reinforced concrete shear wall, i.e., the exposed steel bars or embedded steel plates, or fastened by methods such as through-hole plug welding.

[0039] It is particularly important to clarify that the primary function of the lateral connection structure after construction is to closely link the lateral horizontal displacement of the prefabricated staircase flights with the deformation of the cast-in-place reinforced concrete shear wall. This structure effectively suppresses any potential independent lateral vibration or swaying of the staircase flights relative to the main structural shear wall. Under seismic loads, horizontal shear force can be reliably transferred and distributed between the prefabricated staircase and the shear wall through this lateral connection structure, via the connection nodes at the mounting slots and the connection points on the shear wall. This ensures the coordinated operation of the staircase and the main structure, preventing out-of-plane instability or impact damage to the staircase flights due to lack of lateral support during earthquakes, thereby improving the overall seismic safety performance of the prefabricated building.

[0040] S600. A gap-filling structure is constructed in the gap and the prefabricated staircase is connected to the cast-in-place reinforced concrete shear wall to form the prefabricated building.

[0041] Specifically, in this step, after the high-end fixed hinge support structure, the low-end sliding hinge support structure, and the lateral connection structure have all been constructed and reached the required strength, the filling gap is finally treated. Construction workers can use foamed polyethylene rods or asphalt-impregnated hemp fibers as backing materials, inserting them deep into the filling gap, and then filling the surface with architectural sealant, such as polyurethane sealant or silicone sealant.

[0042] The completed gap-filling structure directly seals the vertical gap between the precast staircase and the cast-in-place reinforced concrete shear wall, providing fireproofing, smoke isolation, dust prevention, and a decorative appearance. From a higher structural function perspective, due to the elastic properties of its material, this gap-filling structure does not hinder the joint operation between the precast staircase and the shear wall achieved through the aforementioned connection structure. Instead, it flexibly fills the visible gaps left after the installation of the connecting components, seamlessly integrating the precast staircase and the cast-in-place reinforced concrete shear wall in terms of both architectural appearance and function. This completes the final step in the prefabricated building construction method, ultimately producing a prefabricated building that meets the design requirements.

[0043] In this embodiment, by reserving and constructing functionally differentiated connection structures at the high end, low end, and sides of the cast-in-place main structure and the precast staircase, namely, a high-end fixed hinge support structure in the first anchorage gap, a low-end sliding hinge support structure in the second anchorage gap, a lateral connection structure at the installation groove and connection position, and a gap-filling structure in the filling gap, a precast staircase and main structure connection system that can both transmit bending moment and shear force and coordinate deformation is systematically constructed. This avoids the drawbacks of existing technologies, such as limited space for on-site grouting operations, stringent requirements for the precision of steel reinforcement holes, and unclear force transmission paths at nodes, significantly improving construction efficiency and installation error tolerance, while ensuring the integrity and safety of the structure under loads such as earthquakes.

[0044] In one embodiment, step S100 includes: S110. In the pre-designated construction area, steel reinforcement binding operations are carried out to form a first steel reinforcement cage for constructing the two layers of the load-bearing beams and a second steel reinforcement cage for the cast-in-place reinforced concrete shear wall.

[0045] Specifically, construction workers measure and mark out the floor or foundation top surface of the pre-designated construction area according to the structural construction drawings. Subsequently, they use longitudinal main reinforcement bars and transverse stirrups of the appropriate specifications to carry out the binding work.

[0046] It is important to clarify that the first reinforcing cage refers to a steel reinforcement framework specifically designed to form the upper and lower load-bearing beam layers. This first reinforcing cage is tied according to the cross-sectional dimensions and span requirements of the load-bearing beams, and its interior contains structural reinforcement such as bottom or top longitudinal main bars to withstand bending moments, stirrups to resist shear forces, and web reinforcement. The second reinforcing cage refers to a steel mesh or framework used to form a cast-in-place reinforced concrete shear wall that surrounds and connects the two load-bearing beam layers. This second reinforcing cage is typically composed of vertical and horizontal distribution bars tied together, and is cross-tied, tied, or welded to the first reinforcing cage at the beam-wall junction area, thus forming a unified load-bearing framework in space. By pre-tying these two reinforcing cages, the thickness of the concrete cover and the position of the internal reinforcing bars of the load-bearing beam layers and shear walls are clearly defined, providing a stable reference for the precise positioning of subsequent embedded components and preventing arbitrary displacement of embedded parts during the pouring of flowing concrete.

[0047] S120. A welding anchoring mechanism is pre-embedded in the second reinforcing cage; wherein the welding anchoring mechanism connects a connecting screw and an anchor plate, the connecting screw is welded to the main reinforcement bar in the second reinforcing cage, the connecting screw extends out of the second reinforcing cage along the thickness direction of the second reinforcing cage toward the first reinforcing cage and connects with the anchor plate, the anchor plate is exposed outside the second reinforcing cage, and the location of the anchor plate forms the connection position.

[0048] In practice, construction workers securely fix one end of the connecting bolt in the welding anchoring mechanism to the vertical main reinforcement or horizontal distribution reinforcement on the side of the second reinforcing cage closest to the precast staircase installation using double-sided welding or lap welding. The welding operation must ensure that the weld length and fullness meet the specifications to provide sufficient tensile strength.

[0049] S130. Formwork is erected around the first and second reinforcing cages; wherein the side of the anchor plate facing the first reinforcing cage is exposed on the formwork.

[0050] Specifically, during formwork erection, wooden, steel, or aluminum formwork systems are used. Special attention needs to be paid to ensuring that the exposed surface of the anchor plate (facing the first reinforcing cage) is tightly fitted against the inner surface of the formwork on the inner side of the shear wall, corresponding to the embedded anchor plate. To prevent concrete slurry from seeping into the gap between the anchor plate and the formwork and covering the anchor plate during pouring, sponge strips or double-sided tape are typically applied around the anchor plate for sealing. With this formwork method, after the concrete hardens and the formwork is removed, this side of the anchor plate can be completely and unobstructed outside the inner wall surface of the cast-in-place reinforced concrete shear wall, serving as a connection point for direct welding operations.

[0051] S140. Perform in-situ concrete pouring to form the two layers of the load-bearing beams and the cast-in-situ reinforced concrete shear wall.

[0052] Specifically, after the formwork is firmly erected, the protective layer pads are in place, and the concealed works have passed inspection, the concrete pouring operation can begin. Fluid concrete is poured into the formwork cavities containing the first and second reinforcing cages using pumps or hopper hoisting methods, and is further compacted with immersion vibrators to remove air bubbles and ensure the concrete densely fills the interior of the reinforcing cages and around the anchor plates.

[0053] After the concrete hardens and reaches the specified curing age, the formwork is removed, revealing two layers of load-bearing beams spaced apart along the height on both sides, and a cast-in-place reinforced concrete shear wall surrounding the two load-bearing beam layers, with exposed anchor plate connection points at specific elevations on the inner wall surface. The connection points where these exposed anchor plates are located provide a solid material foundation for the precise, rapid, and reliable construction of the subsequent precast staircase lateral connection structure.

[0054] In one embodiment, each of the load-bearing beam layers has an anchorage position at its top, and a pre-embedded anchor bolt is provided at the anchorage position; Step S300 includes: S310. A conical hole is reserved at the high end of the prefabricated staircase; wherein the taper of the conical hole faces the bottom surface of the prefabricated staircase.

[0055] Specifically, the anchorage location refers to a specific structural point pre-marked and reserved in the top support area of ​​the load-bearing beam layer, based on the plane coordinates required for the installation of the precast staircase's upper end, during the binding of the first reinforcing cage and concrete pouring of the load-bearing beam layer. The pre-embedded anchor bolt is a metal rod pre-embedded and anchored into the concrete of the load-bearing beam layer at this anchorage location. The lower end of this pre-embedded anchor bolt typically has a hook, anchor plate, or threaded section to weld or mechanically connect with the reinforcing cage within the load-bearing beam layer, ensuring sufficient pull-out anchoring force in the concrete. Its upper end extends vertically upwards and protrudes a certain length from the top surface of the load-bearing beam layer, and is machined with external threads. The function of this exposed threaded section is to provide a force application point for the nut tightening after passing through the pre-reserved hole at the upper end of the precast staircase. By pre-setting anchoring positions with pre-embedded anchors at the top of each load-bearing beam layer, the high end of the precast staircase can obtain a precise connection base point with clear three-dimensional coordinates and high load-bearing capacity when it connects with the load-bearing beam layer, thus avoiding positioning deviations and structural damage caused by on-site drilling and rebar installation.

[0056] During the prefabrication stage in the factory, a conical hole is pre-embedded in the high-end support area of ​​the prefabricated staircase using a specially designed conical mold or polystyrene foam block. This conical hole extends along the thickness direction of the prefabricated staircase, with its upper end located on the top surface or tread surface of the prefabricated staircase and its lower end located on the bottom surface of the prefabricated staircase.

[0057] It is important to clarify that the taper of the conical hole faces the bottom surface of the precast staircase, meaning that the cross-sectional diameter of the hole gradually increases from the top to the bottom of the precast staircase, forming an inverted frustum-shaped cavity that is smaller at the top and larger at the bottom. This specific geometric shape has significant structural and functional implications: when high-strength, non-shrink grout is subsequently injected into the hole, the hardened grout clumps, due to their top-smaller-bottom-larger shape, will be wedge-bound by the concrete wall of the hole when subjected to the tightening pressure of the nuts from the top surface of the precast staircase or the upward pull-out force generated by vibration during use, preventing them from detaching upwards. This structural measure, through pure geometric interlocking, greatly enhances the bonding reliability and pull-out bearing capacity between the grout and the precast staircase concrete, effectively preventing the loosening and detachment of grout in traditional straight-hole grouting under long-term loads or vibrations.

[0058] S320. Pass the pre-embedded anchor bolt through the conical hole and initially tighten it on the top surface of the prefabricated staircase using nuts and washers.

[0059] Specifically, after the prefabricated staircase is hoisted into place, with its upper end stably erected on the upper load-bearing beam and its lower end on the lower load-bearing beam, the construction personnel must ensure that the upper end of the pre-embedded anchor bolt extending from the anchoring position at the top of the load-bearing beam is accurately aligned with and passes through the conical hole reserved at the upper end of the prefabricated staircase. Because the lower end of the conical hole has a relatively large diameter, it provides greater tolerance for the insertion of the pre-embedded anchor bolt, reducing the precision requirements and operational difficulty of the hoisting and alignment.

[0060] After the pre-embedded anchor bolts emerge from the upper end of the conical hole, the construction workers immediately insert steel flat washers and spring washers sequentially onto the top surface of the precast staircase, and then screw in nuts that match the threads of the pre-embedded anchor bolts. A torque wrench is used to apply the specified pre-tightening torque to initially tighten the nuts. This initial tightening serves two purposes: firstly, it temporarily presses the upper end of the precast staircase against the leveling layer or steel shims on the top surface of the load-bearing beam, eliminating any lifting misalignment and achieving geometric stability in the initial installation stage; secondly, the vertical preload applied by the nuts creates a tight, compressed contact between the upper end of the precast staircase and the load-bearing beam, providing favorable boundary conditions for subsequent grouting of the first anchorage gap and preventing grout leakage from the joint surface.

[0061] S330. Before injection, the inner wall of the conical hole is moistened.

[0062] Specifically, before injecting high-strength, non-shrink grout into the conical hole, the inner concrete surface of the hole must be moistened. This can be done by spraying clean water onto the inner wall of the hole with a sprayer, or by wiping the hole wall with a damp sponge or cotton cloth.

[0063] It is important to clarify that the purpose of this wetting treatment step is as follows: The precast staircase concrete is in a hardened and dry state. If it directly contacts the fluid, high-strength, non-shrink grout, the dry concrete pore walls will rapidly absorb moisture from the grout, causing an unfavorable change in the water-cement ratio at the interface. This results in incomplete hydration, reduced interfacial bond strength, and even shrinkage cracks. Pre-wetting ensures the pore wall concrete reaches a saturated, surface-dry state, preventing it from drawing moisture from the grout and avoiding a reduction in grout concentration due to surface water. This measure ensures the grout can fully hydrate during the hardening process, forming a dense, high-strength bond interface with the precast staircase concrete pore walls. This allows the geometric wedging effect of the conical hole and the material bonding effect to work together, thus guaranteeing the overall anchoring performance and long-term durability of the high-end fixed hinge support node.

[0064] S340. Continuously inject high-strength non-shrink grout to a level slightly higher than the conical hole opening, and then perform a troweling process; wherein, the strength grade of the high-strength non-shrink grout is C, and C≥C40.

[0065] Specifically, after wetting and waiting until there is no obvious water accumulation on the borehole wall, the injection of high-strength non-shrink grout should begin immediately. The high-strength non-shrink grout slurry, which is accurately weighed and thoroughly mixed according to the water-to-material ratio specified in the product instructions, is continuously and uninterruptedly injected into the upper end of the conical borehole through a hopper or pressure grouting pump.

[0066] It is important to specify that the strength grade C of the high-strength, non-shrink grouting material mentioned here is not lower than C40 (C≥C40), meaning its 28-day standard cubic compressive strength is not lower than 40 MPa. This strength grade of grouting material is chosen because this node, as a high-end fixed hinge support, needs to withstand and transmit the significant local compressive stress generated by the staircase's inclined support. A strength grade of C40 or higher ensures that the grouting material agglomerates will not crush or undergo plastic deformation under the pre-tightening force of the embedded anchor bolts and the applied load.

[0067] The grouting process should be completed in one go, until the grout level is slightly higher than the upper end of the conical hole, forming a full bulge. After grouting, once the grout has reached its initial setting state, use a trowel or putty knife to smooth the grout material protruding above the hole. This smoothing process involves leveling, compacting, and finishing the surface of the overflowing grout material, making it flush with the top surface of the precast staircase or forming a regular circular protrusion slightly higher than the top surface. This operation not only improves the appearance quality of the joint, but more importantly, by compacting the surface, it seals the capillary channels inside the grout material, enhancing surface density and impermeability, and preventing external moisture or corrosive media from penetrating the joint along the grout interface.

[0068] In one embodiment, prior to step S400, the method further includes: S700. Clean the base surface of the anchorage position corresponding to the lower end so that the lower end can overlap and cover the corresponding anchorage position.

[0069] Specifically, before the precast staircase is hoisted into place, or before the filling structure for the second anchoring gap has been constructed after the lower end of the precast staircase has been temporarily placed, the construction personnel need to carry out a special cleaning operation on the area on the top of the lower load-bearing beam layer that is used to support the lower end of the precast staircase—that is, the base surface of the anchoring position corresponding to the lower end.

[0070] It is important to clarify that the anchorage location corresponding to the lower end mentioned here refers to a specific planar area formed at the top of the load-bearing beam layer, corresponding to the support range of the lower end of the precast staircase. This anchorage location is typically a concrete leveling surface pre-reserved during the pouring of the load-bearing beam layer, the top surface of the embedded steel plate, or a flat bearing surface formed later by leveling with high-strength mortar. The base surface refers to the upper surface layer that directly contacts the bottom surface of the lower end of the precast staircase or the filling material in the second anchorage gap at this anchorage location. Ultimately, the base surface should be clean, flat, firm, and free of any insulating medium. Under these conditions, when the lower end of the precast staircase is in place, its bottom surface can smoothly overlap and cover the corresponding anchorage location.

[0071] In one embodiment, step S400 includes: S410. A graphite composite slip layer is laid between the anchoring position corresponding to the lower end and the lower end; wherein the graphite composite slip layer is composed of a lower layer of roofing felt, a middle graphite layer and an upper layer of roofing felt, and the coefficient of friction of the graphite composite slip layer is less than 0.1. S420. Pass the pre-embedded anchor bolt through the pre-reserved straight hole or cavity at the bottom of the prefabricated staircase, lock it with double nuts and leave a preset number of threads to form a vertical micro-movement gap, so that the prefabricated staircase can slide in a controlled manner along the longitudinal direction of the load-bearing beam to form the sliding hinge support structure; wherein, the preset number of threads is A, 1 thread ≤ A ≤ 2 threads, and the vertical micro-movement gap is B, 1 mm ≤ B ≤ 2 mm.

[0072] Specifically, after the graphite composite sliding layer is laid and the bottom of the precast staircase is placed on it, the pre-embedded anchor bolts at the anchoring position of the load-bearing beam layer are used to complete the vertical constraint structure of the bottom node.

[0073] During the prefabrication stage in the factory, prefabricated stairs have vertically penetrating straight holes or cavities extending a certain length along the span of the stair slabs, corresponding to the locations of the pre-embedded anchor bolts in the lower support area. The diameter of these straight holes or cavities is larger than the diameter of the pre-embedded anchor bolts to provide sufficient space for subsequent sliding movements.

[0074] During construction, the upper end of the pre-embedded anchor bolt is passed through the straight hole or cavity at the bottom of the precast staircase. Then, flat washers are sequentially fitted onto the threaded section of the pre-embedded anchor bolt on the top surface of the bottom of the precast staircase (corresponding to the upper end of the straight hole or cavity), and double nuts are screwed in. Double nuts refer to two nuts screwed onto the same bolt shank, forming a reliable mechanical anti-loosening structure by tightening the two nuts against each other.

[0075] It is important to clarify that during the tightening process, the double nuts do not directly press against the top surface of the precast staircase. Instead, a predetermined number of turns is intentionally left to create a vertical micro-movement gap. The predetermined number of turns A ranges from 1 to 2 turns, which is the distance the nut travels from being completely flush against the top surface of the precast staircase and then loosening it by one to two turns in the opposite direction. Correspondingly, the height of the gap formed between the bottom top surface of the precast staircase and the lower surface of the nut during this operation is the vertical micro-movement gap B, which ranges from 1 mm to 2 mm.

[0076] In one embodiment, step S500 includes: S510. A first connecting mechanism is constructed within the mounting groove; wherein the first connecting mechanism includes an angle steel, a pre-embedded component, and a filler; the angle steel is installed within the mounting groove, and one side of the angle steel extends outward from the mounting groove along the width direction of the prefabricated staircase to form a welding position; a vertically arranged through hole is formed on the side of the angle steel located within the mounting groove, the through hole corresponding to a pre-embedded hole preset at the bottom of the mounting groove; the pre-embedded component passes vertically through the through hole and extends into the corresponding pre-embedded hole to anchor the angle steel to the staircase body; the filler fills the mounting groove to pre-embed the angle steel within the mounting groove. S520. Weld the angle steel to the anchor plate; S530. Grout is poured into the top of the angle steel to form the lateral connection structure.

[0077] It is important to clarify that the mortar pouring on top of the angle steel is not merely a decorative finishing touch. Its structural protection functions are: first, to isolate the steel welds and exposed metal components from external air and moisture, preventing steel corrosion and ensuring the long-term durability of the lateral connection structure; second, the mortar protective layer has certain fire-resistant and heat-insulating properties, which can slow down the heating rate of the steel components in the event of a fire, buying valuable time for evacuation; and third, the smooth mortar surface transitions seamlessly with the shear wall and stair treads, making the connection joint invisible in the building's appearance, meeting the requirements of prefabricated buildings for interior aesthetic quality.

[0078] In one embodiment, step S510 includes: The angle steel is anchored in the mounting groove using a pre-embedded component; wherein the pre-embedded component includes an adhesive block and a pre-embedded screw, the adhesive block is filled in the pre-embedded hole, and the pre-embedded screw passes through the through hole and is inserted into the adhesive block to anchor the angle steel to the ladder body.

[0079] In this embodiment, after the adhesive has fully cured, the adhesive block tightly grips the embedded section of the pre-embedded screw, and the upper end of the pre-embedded screw presses the flange of the angle steel against the bottom surface of the mounting groove through its head or a mating nut. Thus, the pull-out anchoring force provided by the adhesive block in the pre-embedded hole and the vertical tightening force applied by the pre-embedded screw at the through hole work together to achieve an anchored connection between the angle steel and the ladder body.

[0080] In one embodiment, step S600 includes: S610. Fireproof rock wool board is filled into the filling gap; wherein, an adhesive cavity is formed at each end of the fireproof rock wool board along its height direction.

[0081] Specifically, after the welding of the lateral connection structure and the grouting of the protective layer have been completed and cured to a sufficient strength, the construction workers begin to fill the gaps.

[0082] It is important to clarify that the filling gap mentioned here refers to a vertically extending gap that is naturally formed or pre-reserved through positioning measures between the side of the precast staircase and the inner wall of the cast-in-place reinforced concrete shear wall. The existence of this gap provides space for constructing a filling structure with fireproofing, sound insulation, and deformation-adaptive functions.

[0083] During the operation, the concrete surfaces on both sides of the filling gap are first cleaned to remove dust, oil stains, and mortar residue that may have dripped during the construction of the lateral connection structure. Then, the fireproof rock wool boards, pre-cut to the width and height of the filling gap, are inserted into the filling gap manually or with the assistance of thin steel sheets.

[0084] It is important to clarify that the fireproof rock wool board is an inorganic fiber board made primarily from natural basalt or diabase, through high-temperature melting and fiberization. Its material properties determine its non-combustibility, meaning it does not produce flame spread or release toxic fumes under fire conditions, and it has extremely low thermal conductivity. Filling the gap between prefabricated staircases and shear walls with it effectively blocks the path of flames and high-temperature smoke from spreading upwards through this vertical channel during a fire, meeting the stringent fire separation requirements of building fire codes for stairwells and non-stairwell areas.

[0085] S620. Fill the two bonding cavities with bonding material to form the gap filling structure and connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall to form the prefabricated building.

[0086] Specifically, after the fireproof rock wool board has been filled and the bonding cavities at its upper and lower ends have been cleaned and moistened, the bonding material is then applied.

[0087] Construction workers use caulking guns or trowels to inject or apply pre-mixed bonding materials, such as polyurethane sealant, silicone weather-resistant adhesive, or polymer cement waterproof mortar with good flexibility and bonding strength, into the bonding cavities at both ends of the fireproof rock wool board. During filling, it is essential to ensure that the bonding material completely fills the entire cavity and forms a tight adhesive contact with the precast stair treads and cast-in-place reinforced concrete shear wall surfaces. After the bonding material cures, a rigid or elastic sealing strip will form at each end of the fireproof rock wool board, firmly bonded to the surrounding concrete structure.

[0088] In one embodiment, step S620 includes: PE rods and structural sealant are sequentially filled into the two bonding cavities to form the gap filling structure and connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall to form the prefabricated building.

[0089] In one embodiment, the placement lengths of both the high-end and low-end ends are not less than the minimum placement length required by the seismic fortification intensity.

[0090] 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 construction method for prefabricated buildings, characterized in that, Includes the following steps: In the pre-designed construction area, reinforced concrete pouring is carried out to form load-bearing beam layers that are spaced apart on both sides along the height direction and cast-in-place reinforced concrete shear walls surrounding the two load-bearing beam layers; wherein, connection positions are formed in the cast-in-place reinforced concrete shear walls. When both load-bearing beam layers and the cast-in-place reinforced concrete shear wall reach the preset strength, the prefabricated staircase is hoisted and its high and low ends are respectively placed on the two load-bearing beam layers; wherein, a first anchoring gap is formed between the high end and the corresponding load-bearing beam layer, and a second anchoring gap is formed between the low end and the corresponding load-bearing beam layer, one side of the prefabricated staircase is located close to the cast-in-place reinforced concrete shear wall and a filling gap is formed between the prefabricated staircase and the cast-in-place reinforced concrete shear wall, and an installation groove is formed in the area of ​​the prefabricated staircase corresponding to the connection position, and the installation groove is located on the stair surface of the prefabricated staircase; A high-end fixed hinge support structure is constructed and filled within the first anchoring gap. A low-end sliding hinge support structure is constructed and filled within the second anchoring gap. A lateral connection structure is provided at the mounting slot and the connection location; A gap-filling structure is constructed in the gap to connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall, thereby creating the prefabricated building.

2. The construction method for prefabricated buildings as described in claim 1, characterized in that, The steps of pouring reinforced concrete in a pre-designated construction area to form load-bearing beam layers spaced apart along the height on both sides and cast-in-place reinforced concrete shear walls surrounding the two load-bearing beam layers include: In the pre-designed construction area, steel reinforcement binding operations are carried out to form a first steel reinforcement cage for constructing the two layers of the load-bearing beams and a second steel reinforcement cage for the cast-in-place reinforced concrete shear wall. A welding anchoring mechanism is pre-embedded in the second reinforcing cage; wherein the welding anchoring mechanism connects a connecting screw and an anchor plate, the connecting screw is welded to the main reinforcement bar in the second reinforcing cage, the connecting screw extends out of the second reinforcing cage along the thickness direction of the second reinforcing cage toward the first reinforcing cage and connects with the anchor plate, the anchor plate is exposed outside the second reinforcing cage, and the location of the anchor plate forms the connection position; Formwork is erected around the outer periphery of the first and second reinforcing cages; wherein, the side of the anchor plate facing the first reinforcing cage is exposed on the formwork. The concrete is poured in place to form the two layers of the load-bearing beams and the cast-in-place reinforced concrete shear wall.

3. The construction method for prefabricated buildings as described in claim 2, characterized in that, Each load-bearing beam layer has an anchoring position at its top, and pre-embedded anchor bolts are installed at the anchoring position. The step of filling the first anchorage gap with a high-end fixed hinge support structure includes: A conical hole is reserved at the high end of the prefabricated staircase; wherein the taper of the conical hole faces the bottom surface of the prefabricated staircase. The pre-embedded anchor bolts are passed through the conical holes and initially tightened on the top surface of the prefabricated staircase using nuts and washers; The inner wall of the conical hole is moistened before injection; High-strength, non-shrink grout is continuously injected to a level slightly higher than the conical opening, and then troweled; wherein the strength grade of the high-strength, non-shrink grout is C, and C≥C40.

4. The construction method for prefabricated buildings as described in claim 3, characterized in that, Before the step of filling the second anchorage gap with the low-end sliding hinge support structure, the method further includes: Clean the base surface at the anchorage position corresponding to the lower end so that the lower end can overlap and cover the corresponding anchorage position.

5. The construction method for prefabricated buildings as described in claim 4, characterized in that, The step of filling the second anchoring gap with the low-end sliding hinge support structure includes: A graphite composite slip layer is laid between the anchoring position corresponding to the lower end and the lower end; wherein the graphite composite slip layer is composed of a lower layer of roofing felt, a middle graphite layer and an upper layer of roofing felt, and the coefficient of friction of the graphite composite slip layer is less than 0.1; The pre-embedded anchor bolts are passed through the straight holes or cavities reserved at the bottom of the prefabricated staircase, locked with double nuts, and a preset number of fasteners is reserved to form a vertical micro-movement gap, so that the prefabricated staircase can slide in a controlled manner along the longitudinal direction of the load-bearing beam to form the sliding hinge support structure; wherein, the preset number of fasteners is A, 1 fastener ≤ A ≤ 2 fasteners, and the vertical micro-movement gap is B, 1 mm ≤ B ≤ 2 mm.

6. The construction method for prefabricated buildings as described in claim 5, characterized in that, The step of constructing a lateral connection structure at the mounting slot and the connection location includes: A first connecting mechanism is constructed within the mounting groove; wherein the first connecting mechanism includes an angle steel, a pre-embedded component, and a filler. The angle steel is installed within the mounting groove, and one side of the angle steel extends outward from the mounting groove along the width direction of the prefabricated staircase to form a welding position. A vertically arranged through hole is formed on the side of the angle steel located within the mounting groove. The through hole corresponds to a pre-embedded hole preset at the bottom of the mounting groove. The pre-embedded component passes vertically through the through hole and extends into the corresponding pre-embedded hole to anchor the angle steel to the staircase body. The filler fills the mounting groove to pre-embed the angle steel within the mounting groove. Weld the angle steel to the anchor plate; Mortar is poured into the top of the angle steel to form the lateral connection structure.

7. The construction method for prefabricated buildings as described in claim 6, characterized in that, The step of installing the first connecting mechanism in the mounting slot includes: The angle steel is anchored in the mounting groove using a pre-embedded component; wherein the pre-embedded component includes an adhesive block and a pre-embedded screw, the adhesive block fills the pre-embedded hole, and the pre-embedded screw passes through the through hole and is inserted into the adhesive block to anchor the angle steel to the ladder body.

8. The construction method for prefabricated buildings as described in claim 7, characterized in that, The step of constructing a gap-filling structure in the gap and connecting the prefabricated staircase to the cast-in-place reinforced concrete shear wall to form the prefabricated building includes: Fireproof rock wool board is filled into the filling gap; wherein, a bonding cavity is formed at each end of the fireproof rock wool board along its height direction; The two bonding cavities are filled with bonding material to form the gap filling structure and to connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall to form the prefabricated building.

9. The construction method for prefabricated buildings as described in claim 8, characterized in that, The step of filling the two bonding cavities with bonding material to form the gap filling structure and connecting the prefabricated staircase with the cast-in-place reinforced concrete shear wall to manufacture the prefabricated building includes: PE rods and structural sealant are sequentially filled into the two bonding cavities to form the gap filling structure and connect the prefabricated staircase with the cast-in-place reinforced concrete shear wall to form the prefabricated building.

10. The construction method of the prefabricated building as described in any one of claims 1 to 9, characterized in that, The placement length of both the high-end and low-end sections shall not be less than the minimum placement length required by the seismic fortification intensity.

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