A new reinforcing method for high-rise building outer pasting reinforced concrete substructure

Abstract

The application discloses a new reinforcing method for an outer-pasted reinforced concrete substructure of a high-rise building, which comprises the following steps: excavating and checking a trench along a building outer periphery foundation pit; pouring a reinforced concrete raft and connecting the reinforced concrete raft with an original foundation; arranging an underground vertical reinforcing member on the raft; removing an original balcony structure and processing an outer wall base layer; forming a shear key groove at a connecting position of the outer wall and implanting connecting steel bars; arranging an outer-pasted reinforced concrete substructure on the outer side of the building outer wall, which comprises an outer-pasted concrete slab wall, outer-added columns, outer-added cross walls, horizontal slab strip beams and a newly-poured balcony structure; after the outer-pasted substructure is removed from a mold, arranging a steel mesh on the surface of the outer wall in the surrounding area of the outer-pasted substructure and spraying concrete to form a reinforced layer with an increased section; and specially reinforcing a stairwell wall. Through the cooperative work of the peripheral constraint substructure and the overall upgrading of the foundation, the overall rigidity and the anti-seismic performance of the old assembled high-rise building are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of reinforcement and renovation of existing building structures, and in particular to a novel reinforcement method for external reinforced concrete substructures of high-rise buildings. Background Technology

[0002] In the 1970s and 1980s, to meet the housing demand brought about by the rapid growth of the urban population, a large number of high-rise residential buildings were constructed in major Chinese cities such as Beijing, Shanghai, and Tianjin. Among them, the "internal casting and external hanging" large formwork structure system was the most representative prefabricated high-rise building structure during this period. This system is also known as "one formwork and three panels," and its basic structure is as follows: the interior walls are made of cast-in-place concrete using large formwork, with a steel mesh reinforcement inside the walls; the exterior walls use precast concrete composite wall panels, supplemented by structural columns and ring beams. This structural system had advantages at the time, such as fast construction speed, high degree of industrialization, and cost savings in some engineering projects.

[0003] However, after nearly half a century of service, these prefabricated high-rise buildings constructed in the 1970s have generally reached or exceeded their original design lifespan (generally 50 years), facing serious structural safety issues. Extensive engineering inspections have revealed the following structural defects in these buildings: the original concrete strength has significantly decreased from its design strength (e.g., C30), with some dropping below C18; the main reinforcing steel is widely corroded due to carbonization of the protective layer and environmental erosion; and the overall structural stiffness, load-bearing capacity, and ductility have significantly decreased. Simultaneously, with the continuous improvement of my country's seismic fortification standards—taking Beijing as an example, the current seismic fortification intensity is 8 degrees—the seismic resistance of these old buildings can no longer meet the requirements of current mandatory standards, posing significant structural safety hazards. They urgently require overall seismic reinforcement and renovation to meet the requirements for continued use.

[0004] Currently, the main technical approaches for seismic reinforcement of existing buildings include increasing the cross-section, external steel reinforcement, steel plate bonding reinforcement, fiber composite material bonding reinforcement, and external steel structure reinforcement.

[0005] The enlarged section method mainly improves the load-bearing capacity and stiffness of components such as beams, columns, and shear walls by increasing their cross-sectional dimensions. Although this method has mature construction technology and a wide range of applications, it has significant drawbacks. The newly added concrete components occupy a large amount of indoor space, involve a large amount of wet work, and have a long construction period. It can usually only be implemented after the residents have moved out, which has a significant impact on the normal use of existing buildings.

[0006] External steel reinforcement involves placing steel sections or plates around the original structure and forming a combined load-bearing structure using bolts or welding, which can improve the load-bearing capacity of components to some extent. However, this method uses a large amount of steel, has high requirements for fire resistance and corrosion resistance, and is prone to problems such as steel corrosion and aging of the fireproof layer during long-term service, resulting in high maintenance costs.

[0007] Steel plate bonding and carbon fiber fabric bonding reinforcement methods primarily utilize structural adhesives to bond steel plates or fiber composite materials to the surface of structural members, thereby improving their bending or shear capacity. These methods are convenient to implement and have minimal impact on interior spaces. However, their reinforcement effectiveness largely depends on the properties of the adhesive materials, and they are susceptible to the effects of temperature, humidity, and environmental aging during long-term service, posing risks such as interface delamination and weakened bonding performance. Furthermore, these methods mainly provide localized reinforcement for individual members and are unlikely to significantly improve the overall lateral force resisting system and overall seismic performance of the building.

[0008] In recent years, the method of strengthening existing buildings with external steel structures has been increasingly applied to the overall seismic retrofitting of existing buildings. This method typically involves installing a steel frame or steel bracing system around the building's perimeter. The added steel structure bears a portion of the horizontal load, thereby improving the building's overall seismic performance. While the external steel structure can improve the overall stress state of the building to some extent, the connection points between the steel structure and the original concrete structure are complex, requiring high construction precision. Furthermore, insufficient synergistic stress distribution between the new steel structure and the original main structure can easily occur. In addition, steel structures require high levels of fire resistance and corrosion protection, and their long-term durability is significantly affected by environmental factors.

[0009] While existing external concrete reinforcement schemes can improve the stiffness of building exterior components, most schemes primarily focus on the construction of the new exterior components themselves, neglecting to consider how to establish a reliable load-bearing connection between the new exterior structure and the original main structure, how the new exterior foundation and the original foundation can share the load, and how to gradually establish a complete external load-bearing system throughout the construction process. Some schemes only achieve the integration of the new and old structures through rebar installation or partial connections. The shear resistance of the new and old concrete interface is limited, making it prone to interface slippage under strong seismic forces, thus failing to fully utilize the overall seismic resistance of the new exterior structure.

[0010] On the other hand, the overall reinforcement of the exterior of existing buildings typically involves multiple construction stages, including foundation construction, underground structure construction, partial demolition of the main structure, connection between the old and new structures, construction of new exterior structures, waterproofing restoration, and backfilling. These stages have strict construction sequences and load-bearing dependencies. Improper construction organization can not only affect construction safety but may also prevent the new exterior structures from forming a continuous and complete load-bearing system, thereby reducing the overall seismic reinforcement effect.

[0011] Therefore, existing technologies still lack a method for the overall seismic reinforcement of existing buildings that can build around an outer reinforced concrete confined substructure, gradually establish an overall load-bearing system through the addition of a foundation, an underground outer bearing structure, a reliable connection between the old and new structures, and an above-ground outer confined structure, while taking into account construction safety, structural integrity, and long-term durability. Summary of the Invention

[0012] One object of the present invention is to provide a novel reinforcement method for external reinforced concrete substructures of high-rise buildings that at least solves any of the above-mentioned technical problems.

[0013] Specifically, this invention provides a novel reinforcement method for external reinforced concrete substructures of high-rise buildings, comprising the following steps: S1. Excavate the foundation pit along the perimeter of the high-rise building to be reinforced, and inspect the foundation pit around the original foundation. S2. Pour a concrete cushion layer in the foundation construction area formed by excavation, and after setting a steel reinforcement cage on the concrete cushion layer, pour a reinforced concrete raft slab so that the reinforced concrete raft slab and the original foundation structure form an integral load-bearing system. S3. An underground vertical reinforcement component is installed on the reinforced concrete raft slab. The underground vertical reinforcement component includes an external column and an external transverse wall. The underground vertical reinforcement component is connected to the original underground structure of the building to form an external force transmission path independent of the original internal structure of the building. S4. Remove the original balcony structure and exterior wall decoration layer, and treat the original building exterior wall base layer; S5. Shear keyways are formed at the connection points between the original building's exterior wall and the new structure, and connecting steel bars are inserted to form an anchored connection between the original building structure and the new structure. S6. An external reinforced concrete substructure is set on the outside of the building's exterior wall. The external reinforced concrete substructure includes an external concrete slab wall, external columns, external transverse walls, and horizontal slab beams set along the floors. A reinforced concrete balcony structure is recast. The reinforced concrete balcony structure is cast integrally with the external reinforced concrete substructure. S7. Pour the external reinforced concrete substructure. After it is demolded and formed, install a steel mesh on the surface of the original building exterior wall within the area enclosed by the external reinforced concrete substructure, and spray concrete to form an enlarged cross-section reinforcement layer. S8. Special reinforcement of the walls of the building's stairwells and exterior walls; S9. Conduct acceptance testing on the overall reinforced structure.

[0014] Furthermore, in step S2, the reinforced concrete raft slab is connected to the original grid beam foundation by rebar installation.

[0015] Furthermore, in step S5, the shear keyway is formed on the surface of the original building structure by drilling. An interface agent is placed inside the shear keyway, and it is used in conjunction with connecting steel bars to form a shear connection node between the old and new structures.

[0016] Furthermore, the connecting steel bars include a first connecting steel bar for connecting the external column and the external transverse wall, a second connecting steel bar for connecting the slab-beam, and a third connecting steel bar for connecting the external concrete slab wall.

[0017] Furthermore, in step S6, the additional columns are set in the weak areas of the building structure nodes, the additional transverse walls are set on both sides of the building facade, the slab beams are set at intervals along the building floor height direction, and the additional columns and additional transverse walls are connected as a whole.

[0018] Furthermore, the reinforced concrete balcony structure includes a balcony slab, a balcony beam, and a balcony railing, with the balcony railing and the balcony slab being cast simultaneously to form a primary structure.

[0019] Furthermore, in step S7, the steel mesh is connected to the original building exterior wall through L-shaped anchor bars, and the shotcrete is applied in layers to form an enlarged cross-section reinforcement layer for the exterior wall.

[0020] Furthermore, in step S8, the special reinforcement adopts the construction of pre-tensioned steel wire rope mesh in conjunction with basalt tough mortar surface layer.

[0021] Furthermore, in step S5, the depth of the rebar installation is 180mm~255mm, and the diameter of the installation hole is 12mm~16mm.

[0022] Furthermore, underground ring beams are installed between the underground vertical reinforcement components, and all underground vertical reinforcement components together form a closed underground force transmission system with the outer raft slab.

[0023] The technical effects and advantages of this invention are as follows: This invention abandons the traditional indoor reinforcement model, concentrating all main reinforcement work on the exterior of the building walls, basement public areas, and stairwells. It eliminates the need to demolish residents' interior finishes, completely avoiding issues of renovation damage, dust pollution, and noise pollution, thus resolving construction disturbances and resident disputes at their source. Simultaneously, by forming a complete external constraint system through external concrete panels, added columns, added transverse walls, and horizontal slab beams along the floors, combined with shear keyways and rebar anchoring, it effectively constrains the original precast exterior wall panels, precast gable walls, and prefabricated floor and roof slabs. This solves the industry problem of weak prefabricated joints and poor structural integrity that traditional reinforcement methods cannot overcome. Combined with an upgraded overall raft foundation, it achieves coordinated stress distribution between the upper and lower structures, enabling the aged building to stably meet the requirements of an 8-degree seismic fortification, achieving the dual goals of low-interference construction and high-performance reinforcement.

[0024] This invention simultaneously reserves an insulation layer and curtain wall connectors on the outer side of the external wall panel, completing seismic reinforcement and energy-saving renovation in one go. This avoids further disruption to residents' lives caused by secondary construction, shortens the overall construction period, and reduces overall costs. A transfer beam is installed at the top of the external substructure, providing a load-bearing system for future building additions or rooftop photovoltaic system installations. Pre-embedded anchor bolts eliminate the need for separate foundations on the existing roof for later installations, achieving a balance between current reinforcement and future development. Through the comprehensive integration of the external constraint substructure, energy-saving integration, and the top transfer beam, this invention forms a complete technical system with low construction interference, superior structural performance, and comprehensive functional coverage. It fills the gap in non-intrusive comprehensive reinforcement technology for old prefabricated high-rise buildings. The technology is replicable and highly scalable, possessing significant engineering demonstration and industry-leading value. Attached Figure Description

[0025] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic diagram of the overall reinforcement structure of the present invention.

[0026] Figure 2 For the present invention Figure 1 A frontal view of the structure.

[0027] Figure 3 For the present invention Figure 2 Schematic diagram of the cross-sectional structure along the AA direction.

[0028] Figure 4 For the present invention Figure 3 A magnified schematic diagram of a portion of F.

[0029] Figure 5 This is a schematic diagram of the connection and installation structure between the external transverse wall and the building wall of the present invention.

[0030] Figure 6 For the present invention Figure 2 Schematic diagram of the cross-sectional structure in the middle BB direction.

[0031] Figure 7 For the present invention Figure 6 A magnified schematic diagram of part B.

[0032] Figure 8 For the present invention Figure 6 A magnified schematic diagram of the structure of part D.

[0033] Figure 9 This is a cross-sectional view of another configuration of the balcony structure according to the present invention.

[0034] Figure 10 For the present invention Figure 9 A magnified schematic diagram of the structure of E in the middle.

[0035] Figure 11 This is a flowchart outlining the construction steps of the present invention.

[0036] Figure 12 This is a schematic diagram of the underground annular connecting beam location structure of the present invention.

[0037] Figure 13 This is a schematic diagram of the main structure for installing the reinforcing mesh of the present invention.

[0038] In the diagram: 100, underground vertical reinforcement component; 2, steel mesh; 200, reinforced concrete raft slab; 201, exterior wall; 202, foundation layer; 203, original bearing beam; 300, external reinforced concrete substructure; 301, external column; 302, slab-beam; 303, external transverse wall; 304, slab wall; 305, underground ring connecting beam; 400, ground surface; 500, balcony structure; 501, balcony beam; 502, balcony slab; 503, building wall; 600, shear keyway; 601, connecting reinforcement. Detailed Implementation

[0039] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Figure 1 This is a schematic diagram of the overall reinforcement structure of the present invention. Figure 2 For the present invention Figure 1 A frontal view of the structure. Figure 3 For the present invention Figure 2 Schematic diagram of the cross-sectional structure along the AA direction. Figure 4 For the present invention Figure 3 A magnified schematic diagram of a portion of F. Figure 5 This is a schematic diagram of the connection and installation structure between the external transverse wall and the building wall of the present invention. Figure 6 For the present invention Figure 2 Schematic diagram of the cross-sectional structure in the middle BB direction. Figure 7 For the present invention Figure 6 A magnified schematic diagram of part B. Figure 8 For the present invention Figure 6 A magnified schematic diagram of the structure of part D. Figure 9 This is a cross-sectional view of another configuration of the balcony structure according to the present invention. Figure 10 For the present invention Figure 9A magnified schematic diagram of the structure of E in the middle. Figure 11 This is a flowchart outlining the construction steps of the present invention. Figure 12 This is a schematic diagram of the underground annular connecting beam location structure of the present invention. Figure 13 This is a schematic diagram of the main structure for installing the reinforcing mesh of the present invention.

[0041] Example 1 This example focuses on a 12-story prefabricated high-rise residential building constructed in 1977. The building employs a "cast-in-place, externally attached" large-formwork structural system. The original design concrete strength grade was C30, but testing revealed that the current concrete strength has decreased to C18, and the main reinforcing steel is widely corroded. Overall seismic reinforcement is required to meet Beijing's seismic fortification requirements of intensity 8. The building's original foundation consisted of a grid beam and pile structure, not a monolithic raft foundation or box foundation, resulting in poor overall foundation stiffness and dispersed stress.

[0042] The novel reinforcement method for external reinforced concrete substructures of high-rise buildings in this embodiment includes the following steps: Preliminary preparations and safety protection during construction Preparatory work for the project was completed ahead of schedule, and a special guarantee plan was developed for the construction characteristics of old residential areas. This included: organizing the temporary relocation of residents; maintaining complete records of existing balconies and interior decorations; strictly adhering to the original demolition and restoration standards to ensure that the quality of the restored decoration was no less than the original standards; completing a special demolition plan and expert review for the critical balcony demolition project; and comprehensively setting up sound insulation, noise reduction, and dust control facilities at the construction site to avoid construction pollution and noise disturbance. Simultaneously, the distribution of pipelines around the building was investigated, and the relocation of various buried pipelines such as gas, heating, electricity, telecommunications, water supply, and sewage was completed to provide working conditions for earthwork excavation and foundation construction.

[0043] Step 1: Foundation Pit Excavation and Foundation Inspection The foundation trench was precisely excavated 400 meters around the building's outdoor ground level. Simultaneously, the original basement ground structure was broken up and demolished, and the trench was uniformly excavated down to the elevation of the original basement's grid beam foundation surface, ensuring sufficient working surface for foundation construction. After excavation, conventional probing techniques were used to test the foundation trench. In conjunction with the supervision and design units, a trench inspection was conducted to confirm that the foundation soil met standards, had no adverse geological hazards, and ensured uniform and stable foundation bearing capacity.

[0044] Step 2: Construction of the integral raft foundation A 100mm thick C15 concrete cushion layer 202 is poured monolithically on the foundation surface to form a smooth and hardened base layer. Subsequently, reinforcing bars are tied in the outdoor area and the basement core area, and a C30 reinforced concrete raft slab 200 is poured monolithically. Simultaneously, it is connected to the original load-bearing beam 203 to integrate the old and new foundation systems. During construction, the newly constructed raft slab reinforcement is reliably connected to the sides of the original structural grid beams using a rebar anchoring method. Specifically, the anchoring hole positions are determined by marking lines on the sides of the grid beams, holes are drilled using a water drill or electric hammer, the holes are cleaned, structural adhesive is injected, and connecting rebar 601 is inserted. After the structural adhesive cures, the raft slab reinforcement is tied and welded or tied to the anchored rebar. This rebar anchoring connection achieves complete load transfer from the superstructure, solving the defects of poor integrity and insufficient stiffness of the original grid beam foundation, and constructing an integral raft slab load-bearing system. It should be noted that the connecting rebar 601 in the rebar anchoring connection... Figure 5 The connection method between the intermediate plate wall 304 and the building wall 503 is the same.

[0045] Step 3: Basement overall waterproofing construction After the raft foundation concrete reaches its design strength, overall waterproofing construction will commence. 3 and 4SBS type II polyurethane membranes will be used as the primary waterproofing material, providing full coverage waterproofing for both the indoor and outdoor raft foundations. The outdoor waterproofing membrane will be rolled up 503mm along the building walls to 500mm above the outdoor ground level, while the indoor waterproofing membrane will be rolled up 250mm along the walls. Throughout the process, the waterproofing membrane will be ensured to be laid tightly, without hollow areas, damage, or overlapping, preventing basement seepage and dampness, and guaranteeing the durability of the foundation structure.

[0046] Step 4: Casting of underground vertical reinforcement components (100mm) and backfilling of foundation trench. like Figure 1 and Figure 2 As shown, the vertical reinforcement of the structural members is tied based on the newly constructed raft foundation. The vertical reinforcement of the external column 301 and external transverse wall 303 is rooted in the raft foundation and anchored to the structural reinforcement of the basement exterior wall 201 to ensure the integrity of the underground structure. Specifically, vertical reinforcement is reserved or installed at the corresponding positions in the raft foundation. The anchorage depth and lap length of the vertical reinforcement should comply with the relevant provisions of the "Code for Design of Strengthening Concrete Structures" (GB 50367). Formwork is erected strictly according to the design dimensions, and C30 concrete is poured integrally to complete the construction of the underground external column 301 and external transverse wall 303. After the strength of the components meets the standards, 2:8 lime-soil is used to backfill and compact the outdoor foundation trench and the interior room core in layers. The compaction degree meets the design requirements of the code, completing the overall structural reinforcement construction of the basement. Demolition of above-ground structures and treatment of the base layer A silent demolition method using hydrostatic shears and pneumatic drills was employed to remove the existing old balcony structure (500mm) and the exterior wall decorative layer (201mm). The structure was broken into small pieces, which were then transported vertically in cassettes and manually bagged and lowered to minimize construction noise and dust pollution. For the existing internally cast and externally clad exterior wall (201mm structure), debris and loose layers on the base wall were removed to ensure a solid and flat base for subsequent keyway construction and rebar installation.

[0047] Step 5: Construction of 600mm Shear Keyway Drilling and Precision Rebar Installation To ensure reliable anchoring between the external substructure and the original main structure and improve the overall collaborative stress performance, shear keyways of 600mm are installed at the connection points between the new and old structures according to the design spacing.

[0048] A 200mm diameter water drill was used to drill 180mm into the 503 wall of the building to form a keyway. The perimeter of the keyway was fully coated with an interface agent to enhance the bonding performance.

[0049] Simultaneous and precise rebar installation is carried out, with specific parameters strictly controlled according to standardized procedures. The connecting steel bar 601 is specifically as follows: First connecting reinforcement: At the junction of the external transverse wall 303, external column 301, and the original external wall 201 slab: vertical keyways 600 are spaced at 600mm intervals, with matching rebar holes of 16mm diameter, using grade III 12 steel bars, with a rebar depth of 180mm (15d), and the ends protruding 290mm, evenly distributed along the keyways 600. According to the "Code for Design of Strengthening Concrete Structures" (GB 50367), for HRB400 steel bars with a diameter of 12mm, the tensile anchorage depth in C30 concrete under non-seismic conditions is approximately 15d (i.e., 180mm). In this embodiment, the rebar depth of 180mm meets the code requirements; Second connecting reinforcement: At the junction of the slab beam 302 and the original exterior wall slab 201: horizontal keyway 600 spacing 600mm, matching anchoring hole diameter 16mm, using grade III 12 steel bars, anchoring depth 180mm (15d), end protrusion 290mm; Third connecting reinforcement: At the junction of the external concrete slab wall 304 and the original external wall panel: Grade III 8 steel bars are used, arranged in a quincunx pattern at @600×600mm, with a bar hole diameter of 12mm and a bar depth of 255mm. The ends are hooked to hook the outer wall panel reinforcement mesh 2. At the junction of balcony slab 502 and the original structure: Grade III 10 steel bars are used, with a spacing of 300mm, a rebar depth of 255mm, and an end protrusion of 600mm to ensure reliable anchoring of balcony structure 500. Before rebar installation, a pull-out test should be conducted on-site to determine whether the rebar and adhesive meet the design requirements. The sampling inspection rate after installation should not be less than 1% of the number of rebars installed, and should include at least three rebars. Hot-rolled ribbed steel bars should be used for rebar installation; plain round steel bars are not permitted.

[0050] Step 6: Construction of the overall casting of the ground-level external cladding structure The construction adopts a sequential, floor-to-floor construction method, prioritizing the completion of reinforcement binding and formwork support for core components such as external columns 301, external transverse walls 303, balcony beams and slabs, and slab-belt beams 302, followed by the unified pouring of C30 concrete. External columns 301 are located in weak areas of the building structure, external transverse walls 303 are located on both sides of the building facade, and slab-belt beams 302 are spaced along the building's floor height, connecting all external columns 301 and external transverse walls 303 into a unified structure.

[0051] The balcony balustrade was optimized from a traditional secondary structure to a single, integrally cast structure. The reinforced concrete balcony structure 500 comprises the balcony slab 502, balcony beam 501, and balcony balustrade. The balcony balustrade and balcony slab 502 are cast simultaneously to form the primary structure, significantly improving the integrity and seismic performance of the balcony structure 500. This allows the forces on the balcony structure 500 to be directly applied to the reinforced concrete raft slab 200 at its base, while simultaneously being fixedly integrated with the overall external structure. During construction, strict control was exercised over the horizontal component support system. Premature formwork removal was strictly prohibited for horizontal components such as the balcony beams, slabs, and slab-belt beams 302. Supports could only be removed after curing to the specified design strength to prevent structural deformation and cracking. It should be noted that the balcony beams are slab-like structures mounted on the balcony beams, with the lower part being the balcony beam and the upper part being the cast-in-place concrete slab of the balcony.

[0052] It should be noted that external transverse walls 303 are provided on both sides of the balcony slab 502. These external transverse walls 303 do not provide good lighting for the balcony and affect the view. To improve the user experience, they can be directly installed on the external columns 301 to increase the balcony's lighting and make the balcony more stable and evenly stressed. Specifically, as shown below... Figure 4 and Figure 10 As shown in the image.

[0053] Step 7: Strengthen the exterior wall by increasing the cross-section with 201 shotcrete. After the external column 301 and the slab-beam 302 are demolded and formed, the original structural slab wall 304 area within their enclosure will be reinforced by increasing its cross-section. For example... Figure 13 As shown in the diagram, the main body of the reinforcing mesh 2 is installed by binding a single layer of bidirectional reinforcing mesh 2. The reinforcing mesh 2 is connected to the original building exterior wall 201 through L-shaped anchor bars, which are reliably connected to the base layer. C30 concrete is sprayed in layers to complete the overall thickening and reinforcement of the exterior wall 201, filling the structural strength deficiency of the original exterior wall 201 and forming an integrated load-bearing system with the external reinforced concrete substructure 300. During the spraying concrete construction, the spraying distance and angle should be controlled to ensure the concrete density. Curing should be carried out promptly after spraying.

[0054] Step 8: Special reinforcement of stairwells For the side walls of stairwells in the core evacuation routes of the building, a special reinforcement process using pre-tensioned steel wire rope mesh and basalt tough mortar surface layer is adopted to ensure the structural safety and fire protection compliance of the escape routes. In specific construction, pre-tensioned steel wire rope mesh is first installed on the stairwell walls, and then a basalt tough mortar surface layer is applied to form an integral reinforcement layer.

[0055] Step 9: Conduct acceptance testing on the overall reinforced structure. After the overall structure is completed, a full set of acceptance work is carried out in accordance with the specifications, including concrete rebound testing, reinforcement cover measurement, and concrete strength evaluation. At the same time, construction data, concealed works records, and test reports are compiled to complete the overall project completion acceptance.

[0056] It should be further explained that the external columns 301, external transverse walls 303, outer perimeter wall 304 and slab beams 302 enclose and form multiple closed force-bearing units that are continuously arranged along the circumference of the building, so as to improve the overall lateral stiffness and spatial integrity of the external reinforced concrete substructure 300. The external reinforced concrete substructure 300mm is continuously arranged along the circumference of the building to form an outer constraint ring, which provides overall constraint to the main body. In the preferred embodiment, by Figure 12 As shown in the figure, an underground ring beam 305 is also provided between the underground vertical reinforcement components 100. All underground vertical reinforcement components 100 together with the outer reinforced concrete raft slab 200 form a closed underground force transmission system to ensure the stability of the underground structure under stress. Because the raft foundation involves the binding of vertical structural reinforcement, the vertical reinforcement of the external column 301 and external transverse wall 303 is rooted in the raft foundation and anchored to the structural reinforcement of the basement exterior wall 201. When an earthquake occurs, the seismic force is preferentially borne by the external reinforced concrete substructure 300, and is transferred from top to bottom to the raft foundation through the connected external column 301 and underground vertical reinforcement component 100. The force is applied to the reinforced concrete raft 200, forming an independent external force transmission system that is different from the original building foundation's force path. At the same time, by gradually connecting the external reinforced concrete substructure 300, the external reinforced concrete substructure 300 gradually participates in the main structure's load-bearing capacity, achieving a smooth load transfer.

[0057] It should be noted that the raft foundation mentioned in the instruction manual is the reinforced concrete valve plate 200.

[0058] Example 2 The difference between this embodiment and Embodiment 1 lies in the adjustment of the rebar installation parameters. For the original building structure with a low concrete strength grade (such as below C18), the rebar installation depth needs to be appropriately increased. According to the requirements of the "Code for Design of Strengthening Concrete Structures" (GB50367), low-strength concrete (such as below C20) needs to increase the anchorage depth by 25% to 30%. In this embodiment, when the original structure's concrete strength test result is lower than C20, the rebar installation depth is adjusted as follows: the installation depth of Grade III 12 rebar (used for the connection between external column 301, external transverse wall 303, slab beam 302 and external wall 201) is adjusted to 225mm (approximately 18.75d), the installation depth of Grade III 8 rebar (used for the connection of external wall panels) is adjusted to 320mm, and the installation depth of Grade III 10 rebar (used for the connection of balcony slab 502) is adjusted to 320mm. The remaining construction steps are the same as in Embodiment 1.

[0059] Example 3 The difference between this embodiment and Embodiment 1 lies in the foundation type. When the original building foundation is a raft foundation or a box foundation, the overall raft foundation pouring construction in step 3 can be simplified accordingly. Specifically, instead of pouring a new raft slab 200 as a whole, the underground vertical reinforcement component 100 is directly constructed after rebar connection on the surface of the original foundation. However, it is necessary to ensure an effective connection between the old and new foundations, and the rebar spacing and depth should be calculated and determined. The remaining construction steps are the same as in Embodiment 1.

[0060] Example 4 The difference between this embodiment and Embodiment 1 lies in the number of building floors. This embodiment is applied to the reinforcement and renovation of an 8-story old prefabricated high-rise building, approximately 26m in height. Due to the lower building height and relatively smaller horizontal seismic force, the spacing of the slab-beam 302 in step 8 can be appropriately increased, changing from one beam per floor to one beam every two floors. The cross-sectional dimensions and reinforcement of the external column 301 can be appropriately reduced based on calculations. The remaining construction steps are the same as in Embodiment 1.

[0061] Example 5 The difference between this embodiment and embodiment 1 is that the external columns 301, external transverse walls 303 and slab beams 302 in the external reinforced concrete substructure 300 adopt steel-concrete composite structures instead of ordinary reinforced concrete structures, that is, steel frames are configured in the concrete section to form steel-concrete external components.

[0062] Specifically, during the reinforcement binding stage of the external columns 301, external transverse walls 303, and slab beams 302, the steel frame is installed simultaneously. The steel frame uses Q355B grade hot-rolled H-beams or welded cross-shaped steel frames. The steel content of the steel should be controlled between 4% and 8%. The steel frame is reliably connected to the foundation raft slab 200 through anchor plates or embedded parts. The surface of the steel should be cleaned of oil and rust, and shear studs should be installed according to specifications to ensure the coordinated work between the steel and the outer concrete. After the steel frame is installed in place, the outer longitudinal reinforcement and stirrups are tied, and C30 or C40 concrete is poured uniformly after formwork is erected, so that the steel and concrete form an integral whole to share the load.

[0063] Compared with ordinary reinforced concrete external components, steel-concrete composite external components can increase the load-bearing capacity by 30% to 50% under the same cross-sectional size conditions, which can effectively solve the problem of narrow building boundaries and limited cross-sectional size of new external components in old residential areas.

[0064] Example 6 The difference between this embodiment and Embodiment 1 is that the external column 301 in the external reinforced concrete substructure 300 uses a steel pipe confined concrete structure instead of an ordinary reinforced concrete structure. Specifically, an outer steel pipe (round or square steel pipe) is first installed at the location of the external column 301, and a steel cage is tied inside the steel pipe before pouring C30 or C40 self-compacting concrete to form a steel pipe confined concrete external column.

[0065] The outer steel pipe should be made of Q355B grade welded steel pipe or seamless steel pipe, with a wall thickness not less than 6mm and a steel content controlled between 5% and 10%. The steel pipe should be installed in sections and welded on-site, with weld quality meeting the Class II weld standard. After the steel pipe is in place, longitudinal reinforcing bars and stirrups should be tied inside the pipe, and self-compacting concrete should be poured from the top. During pouring, a vibrator should be used to assist in compaction to ensure the concrete is dense. The outer surface of the steel pipe should be treated with anti-corrosion and fire-retardant coating according to specifications.

[0066] Compared to ordinary reinforced concrete columns, steel-tube confined concrete columns exhibit significantly improved load-bearing capacity and ductility due to the circumferential confinement of the steel tubes, which subjects the core concrete to triaxial compression. Under the same load-bearing requirements, the cross-sectional dimensions of steel-tube confined concrete columns can be reduced by 30% to 40%, making them particularly suitable for applications with extremely limited external space where conventional external structural members cannot meet the required dimensions. Furthermore, the steel tubes themselves can serve as formwork for concrete pouring, eliminating the need for formwork erection and accelerating construction.

[0067] Example 7 The difference between this embodiment and Embodiment 1 is that some components of the external reinforced concrete substructure 300 are produced by prefabrication and combined with cast-in-place components on site to form an integral load-bearing system, thereby reducing the amount of on-site wet work and construction noise.

[0068] Specifically, the external concrete slab wall 304 uses precast reinforced concrete wall panels. The reinforcement binding, formwork erection, and concrete pouring and curing are completed in the factory. Precast wall panels have pre-installed connecting steel sleeves and embedded parts. After the precast wall panels are transported to the site, they are hoisted into place using a tower crane or truck crane. Reliable connections are achieved with the pre-reserved steel reinforcement of the cast-in-place external columns 301 and slab-beam 302 using sleeve grouting or pre-reserved steel reinforcement lap connections. After the precast wall panels are installed, micro-expansion concrete is poured at the vertical joints between panels and at the horizontal connections between panels and cast-in-place components to form an integrated load-bearing system.

[0069] Linear components such as external columns 301, external transverse walls 303, and slab-beam 302 are still constructed using cast-in-place methods to ensure the reliability and integrity of node connections.

[0070] Precast and cast-in-place hybrid external structures transfer a large amount of rebar tying, formwork erection, and concrete pouring to the factory. On-site work only requires component hoisting and post-construction of joints, reducing on-site wet work by approximately 60%, significantly reducing construction noise and dust pollution, and shortening the construction cycle by approximately 30%. Simultaneously, the factory production of precast components ensures consistent component quality and reduces the impact of on-site human factors on construction quality. This embodiment is particularly suitable for renovation projects in old residential areas with limited construction sites and where residents are extremely sensitive to construction disturbances.

[0071] Example 8 The difference between this embodiment and Embodiment 1 is that, in the foundation reinforcement stage, in addition to pouring the integral reinforced concrete raft slab 200, micro piles are also driven between the original independent piles or engineering piles to form a pile-raft composite foundation, so as to further improve the foundation bearing capacity and overall stiffness.

[0072] Specifically, after the excavation of the foundation pit in step 2 and before the raft foundation pouring in step 3, micropile holes are arranged between the independent piles below the original grid beam foundation according to the design requirements. Micropiles can be micro-steel pipe piles or micro-reinforced concrete piles, with a pile diameter generally between 150mm and 300mm. The pile length is determined by calculation based on geological conditions and bearing capacity requirements. Small drilling rigs are used for hole drilling. After drilling, steel pipes or reinforcing cages are lowered, and grouting or pouring fine aggregate concrete is performed to form the pile. Micropile construction should be carried out with staggered pile intervals to avoid disturbing the original foundation.

[0073] After the micropiles are constructed, pile caps are installed on the pile tops, and the micropiles' top reinforcement is welded or tied to the raft foundation reinforcement. Then, a reinforced concrete raft foundation 200 is poured integrally, forming a pile-raft composite load-bearing structure with the micropiles, the original engineering piles, and the newly constructed raft foundation 200. The bearing capacity of the micropiles and the original engineering piles is synergistically distributed through the raft foundation 200.

[0074] Compared to a single raft foundation, a pile-raft composite foundation can increase the vertical bearing capacity by 40% to 60%, significantly improving the overall stiffness of the foundation and effectively addressing the shortcomings of insufficient stiffness and dispersed stress in traditional grid beam foundations. Furthermore, the micropile construction equipment is compact, produces minimal vibration and noise, and causes minimal disturbance to the surrounding environment and existing buildings, making it ideal for construction in confined spaces in older residential areas. This embodiment is particularly suitable for reinforcement projects of older buildings with insufficient foundation bearing capacity or where the original foundation has experienced uneven settlement.

[0075] Example 9 Based on Example 1, this embodiment adds rubber seismic isolation bearings to the top of the raft slab, supporting the external substructure and the original superstructure of the building together on the seismic isolation layer, realizing the dual coordinated work of external constraint and foundation seismic isolation, and significantly improving the seismic performance of old buildings in high-intensity seismic zones.

[0076] Specifically, after the raft foundation pouring is completed in step 3 and before the underground vertical reinforcement component 100 is poured in step 5, rubber seismic isolation bearings are installed on the top surface of the raft slab 200 at the designed positions. Lead-core rubber seismic isolation bearings (LRB) or natural rubber seismic isolation bearings (LNR) can be used, and the bearing specifications are determined by calculation based on the superstructure load and seismic fortification requirements. Before installing the seismic isolation bearings, precise layout and positioning should be carried out on the top surface of the raft slab 200 to ensure accurate installation. The pre-embedded steel plate under the bearing is connected to the top surface of the raft slab 200 using high-strength anchor bolts, and the pre-embedded steel plate on the bearing is connected to the transfer beam or transfer slab of the superstructure.

[0077] After the seismic isolation bearings are installed, a reinforced concrete transfer layer, transfer beam, or transfer slab is poured on top of the bearings to transfer the load of the original superstructure to the seismic isolation bearings through the transfer layer. Then, the vertical components of the external substructure (external columns 301, external transverse walls 303, etc.) are constructed from the transfer layer upwards. Isolation joints are set around the seismic isolation bearings according to the specifications to ensure that the seismic isolation bearings can deform freely during an earthquake. The maintenance and inspection passage of the seismic isolation layer should be reserved as required by the design.

[0078] By implementing external constraints and foundation isolation, the external substructure provides overall constraint to the original building, improving structural integrity and collapse resistance. Furthermore, the isolation bearings extend the natural period of the structure and reduce seismic input, significantly lowering the seismic response of the superstructure. According to relevant engineering practices, seismic isolation reinforcement can reduce the seismic load on the superstructure by 50% to 70%. This embodiment is particularly suitable for seismic reinforcement projects of old high-rise buildings in high-intensity seismic fortification zones (8 degrees and above).

[0079] Example 10 Based on Example 1, this embodiment simultaneously reserves an insulation layer and curtain wall connectors on the outside of the 304 external concrete slab wall, completing seismic reinforcement and energy-saving renovation in one go, avoiding further disruption to residents' lives due to secondary construction.

[0080] Specifically, after the completion of the shotcrete enlargement construction of the exterior wall 201 in step 9, and during the concrete curing period, insulation layer connectors and curtain wall connectors are pre-embedded on the outer surface of the exterior wall panel 304 and the shotcrete reinforcement layer according to the design requirements. The connectors are made of stainless steel or hot-dip galvanized material, with one end anchored in the exterior concrete structural layer to a depth of not less than 80mm, and the other end exposed for subsequent installation of the insulation layer and curtain wall keel. The spacing of the connectors should simultaneously meet the stress requirements for fixing the insulation layer and installing the curtain wall keel.

[0081] After the shotcrete reaches its design strength, the insulation layer can be installed on the connectors. The insulation layer can be made of molded polystyrene board (EPS), extruded polystyrene board (XPS), or rock wool board, with the thickness determined based on energy-saving calculations. The insulation board is reliably fixed to the structural layer using connectors, and the joints are sealed with a special adhesive. Fiberglass mesh is installed on the outside of the insulation layer, and a crack-resistant mortar protective layer is applied. Subsequently, the curtain wall joists and decorative panels are installed on the connectors.

[0082] By simultaneously pre-installing connectors on the outer side of the 304 stainless steel exterior wall panels, integrated construction of seismic reinforcement and energy-saving renovation was achieved. Compared to the traditional separate renovation model of reinforcement first and energy saving later, integrated construction avoids repeated disruptions to residents' lives caused by secondary scaffolding erection and secondary construction, shortening the overall construction period by approximately 20% and reducing the overall project cost by approximately 15%. Simultaneously, the pre-embedded connectors ensure the anchoring safety of the insulation layer and curtain wall system, preventing damage to the reinforced structural layer during subsequent anchoring construction. This embodiment is particularly suitable for renovation projects of old residential areas facing the dual needs of seismic reinforcement and energy-saving renovation.

[0083] Example 11 Based on Example 1, this embodiment sets a transfer beam on the top and roof layer of the external reinforced concrete substructure 300 to provide a load-bearing system for future building additions or roof photovoltaic system installation, achieving a balance between reinforcement and renovation and future development.

[0084] Specifically, during the overall casting construction of the above-ground external substructure in step 8, a continuous reinforced concrete transfer beam is added to the top of the external columns 301 and the slab beams 302. The transfer beam is arranged in a closed loop along the outer ring of the building, connecting the tops of each external column 301 into an integral frame. The cross-sectional dimensions and reinforcement of the transfer beam are determined by calculation based on future additions or photovoltaic loads; generally, the beam height should not be less than 500mm and the beam width should not be less than 300mm.

[0085] Anchor bolts or pre-reserved rebar joints for connecting additional columns or photovoltaic supports should be pre-embedded within the transfer beam. The specifications, spacing, and anchorage depth of the anchor bolts or rebar joints should be determined based on future loads. Sufficient operating space and connection work surface should be reserved on the top surface of the transfer beam, and waterproofing treatment should be carried out. After the transfer beam is constructed, its top surface can serve as the installation reference surface for future additions to the steel structure or photovoltaic supports.

[0086] By installing a transfer beam on top of the outer substructure, structural conditions are reserved for future functional upgrades of the building. When additional floors are needed, a steel frame or light steel addition structure can be directly installed on the transfer beam, with the load evenly transferred to the outer substructure and foundation system. When a rooftop photovoltaic system is installed, photovoltaic brackets can be directly fixed to the transfer beam, eliminating the need for a separate foundation on the existing roof. The transfer beam also serves as a replacement for the roof parapet wall, improving roof safety. This embodiment is particularly suitable for applications involving functional upgrades and green energy retrofits of existing buildings in urban renewal projects.

[0087] Example 12 This embodiment combines some of the technical features of embodiments 1 to 11 to form an optimized combination scheme for multiple complex working conditions.

[0088] Specifically, in the selection of external components, the external column 301 adopts a steel pipe confined concrete structure, the external transverse wall 303 and the slab-beam 302 adopt a steel-concrete composite structure, and the external slab wall 304 adopts a precast and cast-in-place hybrid structure, so as to achieve the comprehensive optimization of load-bearing capacity, construction efficiency and site adaptability.

[0089] For foundation reinforcement, a combination scheme of pile-raft composite foundation and seismic isolation bearing is adopted: first, micropiles are added to form a pile-raft composite foundation, and a reinforced concrete raft slab of 200mm is added to improve the bearing capacity of the foundation. Then, rubber seismic isolation bearings are installed on the top of the raft slab of 200mm to form a seismic isolation layer. The external restraint substructure is rooted from the top surface of the seismic isolation layer by the transfer beam, thus realizing a three-level seismic structure of pile-raft composite foundation, seismic isolation layer and external restraint substructure.

[0090] In terms of functional integration, the outer side of the 304 stainless steel exterior wall panel is pre-reserved for insulation layer and curtain wall connectors, completing seismic reinforcement and energy-saving renovation in one go; a transfer beam is set at the top of the exterior substructure to reserve conditions for future addition of floors or photovoltaic installation.

[0091] This comprehensive solution can achieve a balance between load-bearing capacity enhancement, seismic performance optimization, low construction interference, energy-saving renovation, and future functional reservation. It is suitable for reinforcement projects of old high-rise prefabricated buildings in high-intensity seismic fortification zones, with narrow building boundaries, and facing multiple renovation needs.

[0092] Structural performance testing was conducted on the building reinforced using the method described in Example 1. Concrete strength testing: After reinforcement, the rebound method was used to test the strength of the original structure's concrete and the newly added structure's concrete. The test results showed that although the original structure's concrete strength was still around C18, the overall load-bearing capacity of the structure was significantly improved through the overall restraint and load-bearing effect of the external reinforced concrete substructure 300mm; the strength of the newly added C30 concrete components met the design requirements.

[0093] Seismic performance verification was conducted on the reinforced structure in accordance with the "Standard for Seismic Appraisal of Buildings" (GB 50023) and the "Code for Seismic Design of Buildings" (GB50011). The verification results show that the overall stiffness and bearing capacity of the reinforced structure are significantly improved, and it can stably meet the requirements of Beijing's seismic fortification standard of intensity 8.

[0094] In terms of construction interference assessment, all main reinforcement work in this embodiment is concentrated on the outer side of the building's exterior wall 201 and the basement public area. The entire process does not require entering the residents' interiors for construction, nor does it require the removal of the residents' interior finished walls, floors, and ceilings. This effectively avoids the decoration damage, dust pollution, and noise pollution problems associated with traditional methods.

[0095] The quality inspection of the connection between the new and old structures was carried out by sampling inspection of the shear keyway 600 and the rebar connection nodes. The inspection results showed that the concrete in the keyway was poured densely, the interface agent was applied evenly, the pull-out force of the rebar was sufficient, the connection between the new and old structures was reliable, and the joint stress could be achieved.

[0096] 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 novel reinforcement method for external reinforced concrete substructures of high-rise buildings, characterized in that, Includes the following steps: S1. Excavate the foundation pit along the perimeter of the high-rise building to be reinforced, and inspect the foundation pit around the original foundation. S2. Pour a concrete cushion layer in the foundation construction area formed by excavation, and then pour a reinforced concrete raft slab after setting a steel reinforcement cage on the concrete cushion layer, so that the reinforced concrete raft slab and the original foundation structure form an integral load-bearing system. S3. An underground vertical reinforcement component is installed on the reinforced concrete raft slab. The underground vertical reinforcement component includes an external column and an external transverse wall. The underground vertical reinforcement component is connected to the original underground structure of the building to form an external force transmission path independent of the original internal structure of the building. S4. Remove the original balcony structure and exterior wall decoration layer, and treat the original building exterior wall base layer; S5. Shear keyways are formed at the connection points between the original building's exterior wall and the new structure, and connecting steel bars are inserted to form an anchored connection between the original building structure and the new structure. S6. An external reinforced concrete substructure is set on the outside of the building's exterior wall. The external reinforced concrete substructure includes an external concrete slab wall, external columns, external transverse walls, and horizontal slab beams set along the floors. A reinforced concrete balcony structure is recast. The reinforced concrete balcony structure is cast integrally with the external reinforced concrete substructure to form a closed load-bearing unit. S7. Pour the external reinforced concrete substructure. After it is demolded and formed, install a steel mesh on the surface of the original building exterior wall within the area enclosed by the external reinforced concrete substructure, and spray concrete to form an enlarged cross-section reinforcement layer. S8. Special reinforcement of the walls of the building stairwell and the exterior walls, wherein the special reinforcement adopts the construction of pre-tensioned steel wire rope mesh in combination with basalt tough mortar surface layer; S9. Conduct acceptance testing on the overall reinforced structure.

2. The novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, In step S2, the reinforced concrete raft slab is connected to the original grid beam foundation by rebar installation.

3. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, In step S5, the shear keyway is formed on the surface of the original building structure by drilling. An interface agent is placed inside the shear keyway, and it is used in conjunction with connecting steel bars to form a shear connection node between the old and new structures.

4. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 3, characterized in that, The connecting steel bars include a first connecting steel bar for connecting the external column and the external transverse wall, a second connecting steel bar for connecting the slab-beam, and a third connecting steel bar for connecting the external concrete slab wall.

5. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, In step S6, the additional columns are set in the weak areas of the building structure nodes, the additional transverse walls are set on both sides of the building facade, the slab beams are set at intervals along the building floor height direction, and the additional columns and additional transverse walls are connected as a whole.

6. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, The reinforced concrete balcony structure includes a balcony slab, a balcony beam, and a balcony railing, with the balcony railing and balcony slab being cast simultaneously to form a primary structure.

7. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, In step S7, the steel mesh is connected to the original building exterior wall through L-shaped anchor bars, and the shotcrete is applied in layers to form an enlarged cross-section reinforcement layer for the exterior wall.

8. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, In step S8, the pre-tensioned steel wire rope mesh is fixed to the surface of the stairwell wall by anchors, and the basalt tough mortar surface layer is constructed by layering and applying to form a special reinforcement layer for the stairwell.

9. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, In step S5, the depth of the connecting steel bar is 180mm~255mm, and the diameter of the hole is 12mm~16mm.

10. A novel reinforcement method for external reinforced concrete substructures of high-rise buildings according to claim 1, characterized in that, The external reinforced concrete substructure, the external wall enlarged section reinforcement layer, the stairwell special reinforcement layer, and the reinforced concrete raft foundation together constitute the overall seismic reinforcement system of the building; underground ring beams are set between the underground vertical reinforcement components, and the underground vertical reinforcement components together form a closed underground force transmission system with the outer raft foundation.

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