Variable cross-section swing rigid frame reinforcing system and construction method thereof

Abstract

The invention discloses a variable cross-section swing rigid frame reinforcing system which comprises an existing building, multiple layers of vertical constraint assemblies and multiple layers of horizontal constraint assemblies are sequentially and alternately arranged on the periphery of the existing building from a foundation to a roof, and the horizontal constraint assemblies are connected to the periphery of the existing building in a cantilever mode. A portal rigid frame beam is arranged above the top-layer vertical constraint component in a pouring mode. The construction method comprises the following steps that firstly, piling is conducted on the periphery of the existing building and the position where the variable cross-section rigid frame column is planned to be arranged, and a bearing platform is poured; secondly, a vertical reinforcement cage extends out of the bearing platform and is exposed out of the ground, and concrete is poured to form a buttress after formwork erecting; and thirdly, a hinged support is arranged at the top of the buttress. According to the variable cross-section rigid frame column, the lateral stiffness and the anti-seismic bearing capacity of the structure are improved while home-entry construction is not carried out, traffic is not affected, emergency evacuation and parking are not carried out, and the earthquake action borne by an existing building is partially transmitted to the variable cross-section rigid frame column.

Description

Technical Field

[0001] This invention relates to the field of existing building reinforcement technology, specifically to a variable cross-section swaying rigid frame reinforcement system and its construction method. Background Technology

[0002] Existing buildings, as an important component of urban construction and development, are massive in scale and widely distributed, serving multiple social functions such as residence, office, and commerce. However, many existing buildings, due to their age and limitations imposed by the design standards and construction techniques of their time, generally suffer from problems such as low material strength, insufficient structural integrity, and weak joint connections. This makes it difficult for them to meet current code requirements in terms of safety and seismic performance, making them highly susceptible to structural damage or even collapse under natural disasters such as earthquakes. Therefore, effective reinforcement is urgently needed to eliminate these safety hazards.

[0003] Traditional seismic reinforcement methods require in-house construction, which causes significant disturbance and is difficult to implement. While seismic isolation technology can significantly improve the seismic safety performance of a structure, it requires piling inside and around the building, foundation underpinning and seismic isolation retrofitting, as well as flexible connection modifications to water, electricity and gas pipelines, and suspension modifications to elevators and staircases. The amount of pile foundation construction and earthwork excavation is large, the overall renovation cost is high, and the disturbance is significant. Existing building reinforcement projects with large scale and wide scope cannot provide a large number of temporary housing units.

[0004] To address these issues, the industry has developed "external portal frame-built-in prestressed tie rod reinforcement technology," which offers the advantage of eliminating the need for on-site construction and demonstrates significant application potential in the reinforcement of existing buildings. However, in practical engineering applications, this technology still has certain limitations: when existing buildings are adjacent to courtyard walls, fire escape routes within the courtyard, parking spaces, or municipal roads, the portal frame columns need to be grounded, and their bottom components will occupy ground-level space, leading to obstructed passage, blocked fire emergency evacuation routes, or the inability to use parking spaces normally. Consequently, the entire reinforcement solution may be difficult to implement due to its incompatibility with site functional requirements, limiting its widespread application in complex environmental conditions.

[0005] To address the aforementioned shortcomings of existing technologies, the development of a new type of existing building reinforcement technology is of great significance for promoting the large-scale implementation of seismic reinforcement projects for existing buildings, eliminating safety hazards, and protecting life and property. Summary of the Invention

[0006] The purpose of this invention is to provide a variable cross-section swaying rigid frame reinforcement system and its construction method, which solves the problem of needing to carry out on-site construction in the reinforcement and renovation of existing buildings.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A variable cross-section swaying rigid frame reinforcement system includes an existing building. Multiple layers of vertical restraint components and multiple layers of horizontal restraint components are alternately arranged around the perimeter of the existing building, extending from the foundation to the roof. The horizontal restraint components are cantilevered around the perimeter of the existing building. A portal frame beam is cast above the top-level vertical restraint components. Multiple foundations are set around the existing building, and piers are set on top of the foundations, with hinged supports on the top of the piers. The vertical constraint assembly includes multiple variable cross-section rigid frame columns and multiple portal rigid frame columns. The bottom of the multiple variable cross-section rigid frame columns is hinged to the hinge support. Multiple layers of horizontal constraint assemblies and multiple layers of portal rigid frame columns are arranged alternately and in layers above the multiple variable cross-section rigid frame columns. A portal rigid frame beam is cast on the top portal rigid frame column. The variable cross-section rigid frame column is a two-way variable cross-section structure, which is wider at the top and narrower at the bottom, and thinner at the top and thicker at the bottom. The horizontal constraint assembly includes multiple longitudinal partitions and multiple transverse partitions. A longitudinal partition is provided in the longitudinal direction of the existing building, between the tops of two adjacent variable cross-section rigid frame columns or two portal rigid frame columns, and one end of the longitudinal partition is located on the existing building. A transverse partition is provided in the transverse direction of the existing building, between the tops of two adjacent variable cross-section rigid frame columns or two portal rigid frame columns, and one end of the transverse partition is located on the existing building.

[0008] Preferably, a passageway is provided between the variable cross-section rigid frame column and the existing building.

[0009] Preferably, both the longitudinal partition and the transverse partition are located at the elevation of each floor slab.

[0010] Preferably, two variable cross-section rigid frame columns or two portal rigid frame columns arranged opposite each other in the transverse direction of the existing building are connected by steel tie rods, and the steel tie rods penetrate the existing building.

[0011] Preferably, the steel tie rod is a steel bar or steel strand, and both ends are anchored to the variable cross-section rigid frame column or portal rigid frame column.

[0012] Preferably, the steel tie rod can be straight, broken, or curved, and prestress is applied to its end to form an upward arching force. When the vertical bearing capacity of the existing building's internal walls is insufficient, the steel tie rod is unloaded.

[0013] Preferably, the hinge support is a ball joint or a pin. A construction method for a variable cross-section swaying rigid frame reinforcement system includes the following steps: Step 1: Drive piles around the existing building at the locations where variable cross-section rigid frame columns are to be installed, and pour the foundation. Step 2: Extend the vertical steel reinforcement cage from the foundation and expose it above the ground. After setting up the formwork, pour concrete to form the support pier. Step 3: Install hinged supports on the top of the pier; Step 4: Tie steel bars above the pier and cast-in-place variable cross-section rigid frame columns, or assemble variable cross-section rigid frame columns using prefabricated methods. The bottom of the variable cross-section rigid frame column is connected to the top of the pier through a hinged support. Step 5: Connect the steel tie rods between two variable cross-section rigid frame columns that are arranged opposite each other in the transverse direction of the existing building; Step 6: Tie cast-in-place or prefabricated horizontal restraint components above the cross-section rigid frame columns at the first floor elevation of the existing building; Step 7: Tie reinforcing steel bars to the cast-in-place portal frame column above the horizontal constraint components; Step 8: Connect the steel tie rods between two portal frame columns that are arranged laterally and opposite each other in the existing building. Step 9: Tie or install the horizontal restraint components at the second floor level of the existing building. Step 10: Repeat the steps until the top of the portal frame column is located at the existing building roof elevation, and install portal frame beams along the direction of the portal frame column.

[0014] The beneficial effects of this invention are reflected in: This invention proposes a method for reinforcing existing buildings using a swing portal frame system, which has advantages such as no need for entry, minimal site impact, low construction difficulty, and high reinforcement efficiency. This ensures that reinforcement and renovation projects are carried out efficiently and with high quality, thereby meeting the needs of a large number of existing buildings that urgently require reinforcement.

[0015] This invention can be used in existing masonry structures, as well as existing frame structures, bottom-frame brick houses, and inner-frame brick houses, and has good applicability.

[0016] By installing longitudinal and transverse partitions at each floor level, the problems of out-of-plane stability and longitudinal integrity of the portal frame columns are solved, and the space can also be used as a terrace, enhancing the user experience.

[0017] At each floor slab elevation, horizontal restraint components are installed between variable cross-section rigid frame columns or portal rigid frame columns. The horizontal restraint components are reliably connected to the existing floor slabs of each floor to form a horizontal restraint effect. The bottom of the variable cross-section rigid frame column is connected to the column pier through a hinged support, which allows rotation but restricts horizontal and vertical displacement. The portal rigid frame column is reliably connected to the existing structure through rebar or tie rods to form a vertical restraint effect. Finally, the outer swing portal rigid frame reinforcement technology is formed.

[0018] This technology improves the lateral stiffness and seismic bearing capacity of the structure without construction inside the building or affecting traffic, emergency evacuation, and parking, and transfers part of the seismic load borne by the existing building to the variable cross-section rigid frame column.

[0019] When the existing building is a masonry structure, prestress can be applied by steel tie rods or steel strands to generate an upward arching force in the existing building walls. This ensures the overall connection between the portal frame and the main structure, and also unloads the original main structure walls layer by layer, solving the problem of insufficient vertical bearing capacity of the original walls and the need for reinforcement at the building entrance.

[0020] To avoid insufficient bearing capacity caused by the small bottom size of the portal frame column, and damage caused by excessive additional axial force during an earthquake, the variable cross-section frame column is a two-way variable cross-section structure, which is wider at the top and narrower at the bottom, and thinner at the top and thicker at the bottom. The variable cross-section frame column can strengthen the structure while minimizing the impact on functions such as travel, emergency evacuation and parking. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the completed structure in step four of the present invention; Figure 3 This is a partial structural diagram of the present invention; Figure 4 This is a schematic diagram of the completed structure in step five of the present invention; Figure 5 A top view of the structure for this invention; Figure 6 This is a schematic diagram of the hinged support connection structure in one embodiment of the present invention; Figure 7 This is a schematic diagram of the hinged support connection structure in another embodiment of the present invention; In the diagram: 1. Existing building; 2. Vertical restraint component; 3. Horizontal restraint component; 4. Pier; 5. Hinged support; 6. Steel tie rod; 7. Portal frame beam; 8. Pier cap; 20. Variable cross-section frame column; 21. Portal frame column; 30. Longitudinal diaphragm; 31. Transverse diaphragm. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings: like Figures 1 to 7 The variable cross-section swaying rigid frame reinforcement system shown includes an existing building 1. Multiple layers of vertical restraint components 2 and multiple layers of horizontal restraint components 3 are alternately arranged around the existing building 1, extending from the foundation to the roof. The horizontal restraint components 3 are cantilevered around the existing building 1. A portal frame beam 7 is cast and installed above the top vertical restraint component 2.

[0023] Multiple foundations 8 are set on the periphery of the existing building 1, and a support 4 is set on the top of the foundation 8. A hinged support 5 is set on the top of the support 4.

[0024] The vertical restraint assembly 2 includes multiple variable cross-section rigid frame columns 20 and multiple portal frame columns 21. The bottoms of the multiple variable cross-section rigid frame columns 20 are hinged to hinged supports 5. Above the multiple variable cross-section rigid frame columns 20, multiple layers of horizontal restraint assemblies 3 and multiple layers of multiple portal frame columns 21 are arranged alternately and in layers. A portal frame beam 7 is cast and installed on the top layer of portal frame columns 21. In this example, the hinged support 5 is a ball joint or a pin. The portal frame beam 7 and the portal frame columns 21 form a reinforced concrete portal frame.

[0025] The variable cross-section rigid frame column 20 is a two-way variable cross-section structure, wider at the top and narrower at the bottom, with a thinner top and thicker bottom. Specifically, the variable cross-section rigid frame column 20 gradually changes from a rectangular cross-section in the upper section to a rectangular or square cross-section at the connection with the pier 4 in two directions. On the one hand, from the appearance, the thickness change of the variable cross-section rigid frame column 20 is not obvious, and on the other hand, the concrete cross-sectional dimensions at the contact point do not change, reducing safety issues caused by insufficient axial compression ratio.

[0026] A passageway is provided between the variable cross-section rigid frame column 20 and the existing building 1. The horizontal constraint component 3 includes multiple longitudinal partitions 30 and multiple transverse partitions 31. A longitudinal partition 30 is provided in the longitudinal direction of the existing building 1, between the tops of two adjacent variable cross-section rigid frame columns 20 or two portal rigid frame columns 21, and one end of the longitudinal partition 30 is provided on the existing building 1.

[0027] A transverse partition 31 is provided on the transverse side of the existing building 1, between the tops of two adjacent variable cross-section rigid frame columns 20 or two portal rigid frame columns 21, and one end of the transverse partition 31 is provided on the existing building 1.

[0028] Two variable cross-section rigid frame columns 20 or two portal rigid frame columns 21 arranged laterally opposite each other in the existing building 1 are connected by steel tie rods 6, which penetrate through the existing building 1. Specifically, boreholes are provided in the existing building 1, and the two ends of the steel tie rods 6 are anchored to the variable cross-section rigid frame columns 20 or portal rigid frame columns 21. The steel tie rods 6 pass through the boreholes, and the boreholes are filled with polymer mortar or grouting materials or other binding materials.

[0029] Both longitudinal partitions 30 and transverse partitions 31 are installed at the elevation of each floor slab.

[0030] The steel tie rod 6 is made of steel bars or steel strands, and its two ends are anchored to the variable cross-section rigid frame column 20 or the portal rigid frame column 21. The steel tie rod 6 can be straight, broken, or curved, and prestress is applied to its ends to form an upward arching force, so that the variable cross-section rigid frame column 20 or the portal rigid frame column 21 forms a reliable connection with the existing building 1. When the vertical bearing capacity of the internal walls of the existing building 1 is insufficient, the steel tie rod 6 is equivalent to unloading the internal walls.

[0031] When used in existing masonry structures, bottom-frame brick buildings, and internal-frame brick buildings, the longitudinally arranged variable cross-section rigid frame columns 20 or portal rigid frame columns 21 and longitudinal diaphragms can be omitted. Instead, reinforced concrete slab walls can be installed on the gable walls at both ends of the building and the exposed exterior longitudinal walls. The horizontal reinforcement bars of the reinforced concrete slab walls are anchored into the variable cross-section rigid frame columns 20 or portal rigid frame columns 21. The interior walls of public areas such as stairwells are reinforced with a steel mesh mortar surface layer.

[0032] A construction method for a variable cross-section swaying rigid frame reinforcement system includes the following steps: Step 1: Drive piles around the existing building 1 at the location where the variable cross-section rigid frame column 20 is to be installed, and pour the foundation 8. Step 2: Extend the vertical steel reinforcement cage from the foundation 8 and expose it above the ground. After setting up the formwork, pour concrete to form the support pier 4. Step 3: Install hinged support 5 on the top of support 4; Step 4: Tie steel bars above the support 4 and cast in place the variable cross-section rigid frame column 20, or assemble the variable cross-section rigid frame column 20 by prefabrication. The bottom of the variable cross-section rigid frame column 20 is connected to the top of the support 4 through the hinged support 5. Step 5: Connect the steel tie rods 6 between the two variable cross-section rigid frame columns 20 arranged laterally and opposite each other in the existing building 1. Step 6: Tie the cast-in-place or prefabricated horizontal restraint assembly 3 above the first floor elevation of the existing building 1 and the cross-section rigid frame column 20; Step 7: Tie the reinforcing steel bars to the cast-in-place portal frame column 21 above the horizontal constraint component 3; Step 8: Connect the steel tie rods 6 between the two portal frame columns 21 that are arranged opposite each other in the transverse direction of the existing building 1. Step 9: Tie or install the horizontal restraint components 3 at the second floor elevation of the existing building 1; Step 10: Repeat the steps until the top of the portal frame column 21 is located at the roof elevation of the existing building 1, and install the portal frame beam 7 along the direction of the portal frame column 21.

[0033] The above embodiments are merely illustrative of the concept and implementation of the present invention and are not intended to limit it. Under the concept of the present invention, technical solutions without substantial changes are still within the scope of protection.

Claims

1. A variable cross-section swaying rigid frame reinforcement system, comprising an existing building (1), characterized in that: Multi-layer vertical constraint components (2) and multi-layer horizontal constraint components (3) are alternately arranged around the existing building (1) from the foundation to the roof. The horizontal constraint components (3) are cantilevered around the existing building (1). A portal frame beam (7) is cast above the top vertical constraint component (2). Multiple foundations (8) are provided around the existing building (1), and a support pier (4) is provided above the foundation (8). A hinged support (5) is provided on the top of the support pier (4). The vertical constraint component (2) includes multiple variable cross-section rigid frame columns (20) and multiple portal rigid frame columns (21). The bottom of the multiple variable cross-section rigid frame columns (20) is hinged to the hinge support (5). Multiple horizontal constraint components (3) and multiple portal rigid frame columns (21) are arranged alternately and layer by layer above the multiple variable cross-section rigid frame columns (20). A portal rigid frame beam (7) is cast on the top portal rigid frame column (21). The variable cross-section rigid frame column (20) is a two-way variable cross-section structure, which is wider at the top and narrower at the bottom, and thinner at the top and thicker at the bottom; The horizontal constraint component (3) includes multiple longitudinal partitions (30) and multiple transverse partitions (31). A longitudinal partition (30) is provided between the tops of two adjacent variable cross-section rigid frame columns (20) or two portal rigid frame columns (21) in the longitudinal direction of the existing building (1), and one end of the longitudinal partition (30) is provided on the existing building (1). A transverse partition (31) is provided between the tops of two adjacent variable cross-section rigid frame columns (20) or two portal rigid frame columns (21) in the transverse direction of the existing building (1), and one end of the transverse partition (31) is provided on the existing building (1).

2. The variable cross-section swaying rigid frame reinforcement system according to claim 1, characterized in that: A passage is left between the variable cross-section rigid frame column (20) and the existing building (1).

3. The variable cross-section swaying rigid frame reinforcement system according to claim 1, characterized in that: Both the longitudinal partition (30) and the transverse partition (31) are installed at the elevation of each floor slab.

4. The variable cross-section swaying rigid frame reinforcement system according to claim 1, characterized in that: Two variable cross-section rigid frame columns (20) or two portal rigid frame columns (21) arranged opposite each other in the transverse direction of the existing building (1) are connected by steel tie rods (6), and the steel tie rods (6) penetrate the existing building (1).

5. The variable cross-section swaying rigid frame reinforcement system according to claim 4, characterized in that: The steel tie rod (6) is a steel bar or steel strand, and its two ends are anchored to the variable cross-section rigid frame column (20) or portal rigid frame column (21).

6. The variable cross-section swaying rigid frame reinforcement system according to claim 4, characterized in that: The steel tie rod (6) can be straight, broken, or curved, and prestress is applied to its end to form an upward arching force.

7. The variable cross-section swaying rigid frame reinforcement system according to claim 1, characterized in that: The hinge support (5) is a ball joint or a pin.

8. A construction method for a variable cross-section swaying rigid frame reinforcement system according to claims 1-7, characterized in that, Includes the following steps: Step 1: Drive piles around the existing building (1) at the location where the variable cross-section rigid frame column (20) is to be set up, and pour the foundation (8). Step 2: Extend the vertical steel cage on the foundation (8) and expose it to the ground. After setting up the formwork, pour concrete to form the support pier (4). Step 3: Install hinged support (5) on the top of the support (4); Step 4: Tie steel bars above the support (4) and cast in place the variable cross-section rigid frame column (20), or assemble the variable cross-section rigid frame column (20) by prefabrication. The bottom of the variable cross-section rigid frame column (20) is connected to the top of the support (4) through the hinged support (5). Step 5: Connect steel tie rods (6) between two variable cross-section rigid frame columns (20) arranged laterally and opposite each other in the existing building (1). Step 6: Tie cast-in-place or prefabricated horizontal restraint components (3) above the first floor elevation of the existing building (1) and the cross-section rigid frame column (20); Step 7: Tie the reinforcing steel bars to the cast-in-place portal frame column (21) above the horizontal constraint component (3); Step 8: Connect steel tie rods (6) between two portal frame columns (21) arranged laterally and opposite each other in the existing building (1). Step 9: Tie or install the horizontal restraint components (3) at the second floor elevation of the existing building (1). Step 10: Repeat the steps until the top of the portal frame column (21) is located at the roof elevation of the existing building (1), and set up a portal frame beam (7) along the direction of the portal frame column (21).

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