Connecting structure and method for hinging newly-added steel beam and existing concrete cylinder
By using a composite structure of an outer steel plate and an enlarged concrete layer, combined with longitudinal connecting plates and stiffening ribs, a reliable hinged connection between the steel beam and the concrete column was achieved. This solved the problems of unreasonable structural stress and complex construction when connecting the new steel beam to the existing concrete column, and improved the shear bearing capacity and construction safety of the joint.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI ACAD OF ARCHITECTONICS
- Filing Date
- 2026-03-05
- Publication Date
- 2026-04-21
AI Technical Summary
In existing technologies, when a new steel beam is connected to an existing concrete column, there are problems such as an unreasonable structural stress pattern, insufficient shear capacity of the joint, significant damage to the original concrete column, and complex construction.
The structure employs a composite structure consisting of an outer thick steel plate, longitudinal double connecting plates, thick steel ring plates, vertical stiffening ribs, and longitudinal bars and stirrups with enlarged cross-sections. The enlarged cross-section concrete layer is then poured into the column to form a hinged connection. M20 high-strength bolts are used to achieve a reliable hinged connection between the steel beam and the concrete column.
A reliable hinged connection between the steel beam and the column was achieved, meeting the load-bearing capacity requirements under normal use and seismic conditions. This avoids the problems of altered stress patterns and stress concentration in the main structure caused by traditional rigid connections, and reduces damage to the original structure and construction complexity.
Smart Images
Figure CN121897184A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of building structure reinforcement and renovation engineering, specifically a connection structure and method for hinged connection between a new steel beam and an existing concrete column. Background Technology
[0002] As urbanization shifts from incremental expansion to stock renewal, many existing buildings face the need for functional upgrades, spatial restructuring, and lifespan extension. In such renovations, adding steel structure platforms to achieve spatial division and load optimization is one of the most common technical approaches. Steel structures are lightweight, quick to construct, and have high load-bearing capacity, allowing for flexible adaptation to complex spatial requirements, while existing concrete structures (especially columns) are often retained as the main load-bearing components.
[0003] However, the loads from the new steel structure must be reliably transferred to the existing concrete columns. The connection between the new steel beams and the existing concrete columns is a core technical aspect of the renovation project. This connection must not only meet the load-bearing requirements under normal use conditions (such as vertical loads and horizontal wind loads), but also ensure the overall stability of the structure under accidental conditions such as earthquakes, avoiding cascading damage caused by connection failure.
[0004] When adding a steel beam to an existing concrete column, the connection nodes need to solve two core problems simultaneously:
[0005] Mechanical performance requirements: The steel beam and the cylindrical column must form a hinged connection (i.e., only vertical shear force is transmitted, not bending moment). A rigid connection would cause bending moment to be transmitted to the cylindrical column, changing the original stress pattern of the structure (the cylindrical section is mainly subjected to axial force, and bending moment would cause local stress concentration, reducing seismic performance); while a hinged connection can release the bending moment constraint, allowing the steel beam and the cylindrical column to each assume reasonable mechanical roles (in line with the seismic design principle of "strong column, weak beam").
[0006] Construction constraints: Existing concrete columns are typically located in the core area of a building (such as around load-bearing columns or shear walls), and their structural integrity directly affects overall safety. Furthermore, existing structures may have issues such as dense reinforcement and thin protective layers. Therefore, the construction of connection nodes must minimize damage to the original concrete columns (avoiding large-area concrete removal or deep drilling that could damage the reinforcement) while ensuring ease of construction and node reliability.
[0007] To address the aforementioned needs, various methods for connecting new steel beams and concrete columns have been proposed in the industry, as exemplified below:
[0008] Method 1: The concrete column is encased in a monolithic steel sleeve, and fixed by applying preload with high-strength tie bolts. This method has significant drawbacks in practical application: First, the monolithic steel sleeve is difficult to install, especially with an existing superstructure, making it almost impossible to insert it from the top of the column. Second, drilling holes in the concrete column is necessary for the tie bolts, often resulting in significant drilling deviations and even direct damage to the main reinforcement bars. Furthermore, the rigid connection created by this method alters the original structural stress pattern, causing stress concentration in the concrete column at the joint area, which is particularly detrimental to seismic resistance.
[0009] Method 2: The connecting plate is directly connected and fixed to the concrete column using chemical anchors, and then the steel beam is welded or bolted to the connecting plate. While this method is relatively simple to construct, it has several limitations: the load-bearing capacity of the chemical anchors is significantly affected by the concrete strength, resulting in poor performance in low-strength concrete; the anchor group experiences a cluster effect, leading to uneven stress distribution among the anchors, with edge anchors prone to failure first. Studies show that chemical anchors have poor fatigue performance under long-term dynamic loads, especially under repeated horizontal loads, where they are prone to anchorage colloid cracking failure.
[0010] Method 3: Partially encase the concrete column with channel steel or steel plate, then connect it to the cantilever corbel. While this method improves the overall integrity of the joint, it has significant drawbacks: a large amount of welding work is required in the joint area, resulting in a concentrated heat-affected zone; the butt welds of the channel steel require high precision and are difficult to perform on-site; the joint area experiences a sudden change in stiffness, easily becoming a weak point in seismic resistance. This method also makes the interface between the old and new concrete a weak point for shear force transfer, and involves a large amount of wet work and a long construction period. Numerous stiffening ribs are required at the connection between the cantilever corbel and the steel beam, resulting in a complex structure. The connection between the corbel flange and the steel beam flange (when rigidly connected) makes the stiffness of the joint area much greater than that of adjacent members, which does not conform to the design principle of strong column-weak beam.
[0011] In summary, from the perspective of the load-bearing capacity of the newly added steel structure platform, all three methods can provide the required load-bearing capacity for the steel structure platform. However, the construction of methods 1 and 3 is more complicated, with a large amount of on-site welding, and the quality of the welds is difficult to guarantee. In addition, there is a safety hazard of sliding at the shear force transfer surface between the newly added outer steel and the concrete column. Method 2 involves a large amount of on-site rebar installation, which causes greater damage to the original structure. The construction quality and durability of the rebar installation are also average.
[0012] Therefore, it is necessary to design a reinforcement structure and method that can meet the structural bearing capacity requirements and minimize the damage to existing concrete columns caused by the addition of steel beams. Summary of the Invention
[0013] The purpose of this invention is to provide a connection structure and method for hinged connection between a new steel beam and an existing concrete column, so as to solve the problems of unreasonable structural stress mode, insufficient shear bearing capacity of the joint, large damage to the original concrete column and complex construction in the prior art when connecting a new steel beam to an existing concrete column.
[0014] To achieve the above objectives, the present invention provides the following technical solution: a connection structure for hinged connection between a new steel beam and an existing concrete column, wherein the connection structure is configured as a composite structure that hinges the new steel beam to the existing concrete column and enhances the shear bearing capacity of the joint. This composite structure is arranged circumferentially along the existing concrete column and is bonded to the column through a post-cast enlarged cross-section concrete layer. The composite structure includes an outer thick steel plate, longitudinal double connecting plates, a thick steel ring plate, vertical stiffening ribs, enlarged cross-section longitudinal reinforcement, and the new steel beam, wherein:
[0015] A thick steel plate is wrapped around the outer surface of the existing concrete column. The plate is 20mm thick and is tightly bonded to the surface of the existing concrete column with structural adhesive. It is continuously installed along the vertical height of the existing concrete column and is coaxial with the existing concrete column. A fixed thick steel ring plate and vertical stiffening ribs are installed on the outside of the thick steel plate.
[0016] The longitudinal double connecting plate is a pair of parallel thick steel plates welded to the thick steel ring plate. The longitudinal double connecting plate is 16mm thick. The longitudinal double connecting plate is perpendicular to the horizontal direction of the new steel beam axis and is connected to the end of the new steel beam through M20 high-strength bolts to form a hinged force transmission path between the new steel beam and the concrete column.
[0017] The thick steel ring plate is located in the middle of the outer thick steel plate near the top or bottom of the existing concrete column. It is 20mm thick and is evenly segmented along the circumferential direction of the cross-section of the existing concrete column. Its inner side is welded to the outer thick steel plate, and its outer side is connected to the longitudinal double connecting plate by high-strength bolts. The thick steel ring plate is used to provide local stability of the connection part and a bolt anchoring platform.
[0018] The vertical stiffeners are vertical steel plates spaced vertically along the existing concrete cylinder. They are 8mm thick and are welded to the outer thick steel plate on the inner side and connected to the thick steel ring plate on the outer side. The vertical stiffeners are used to enhance the lateral stiffness and overall stability of the connection nodes.
[0019] The enlarged section concrete layer is a rough bonding surface formed by surface roughening of the existing concrete cylinder surface, which is formed by post-pouring grouting material. The enlarged section concrete layer wraps the enlarged section longitudinal reinforcement and enlarged section stirrups.
[0020] The enlarged section longitudinal reinforcement is arranged in a ring around the perimeter of the existing concrete column and is anchored inside the enlarged section concrete layer (anchorage depth ≥ 15d). The enlarged section longitudinal reinforcement is used to bear the main shear resistance in the joint area and provide longitudinal reinforcement.
[0021] The enlarged section stirrups are wrapped around the outside of the enlarged section longitudinal reinforcement. The enlarged section stirrups are used to restrain the enlarged section concrete layer and improve the compressive strength of the concrete in the joint area. After being tied and fixed, they together form the enlarged section area.
[0022] Preferably, the increased cross-section stirrups are HRB400 grade steel bars with a diameter of 8mm and a spacing of 200mm.
[0023] Preferably, the longitudinal reinforcement bars with increased cross-section are HRB400 grade steel bars with a diameter of 16mm and a spacing of 200mm.
[0024] The method for achieving the hinged connection between the newly added steel beam and the existing concrete column includes the following steps:
[0025] Step 1: Surface treatment and installation of the outer steel plate for the cylinder. First, determine the elevation and range of the new steel beam. Roughen the surface of the existing concrete cylinder (using mechanical sandblasting or manual roughening to create a uniform, uneven texture, increasing the bonding area). Clean the surface of dust and debris. Then, hoist a 20mm thick outer steel plate, continuously wrapping it along the entire vertical height of the cylinder and coaxial with it. Use structural adhesive (high-strength epoxy structural adhesive, applied 2-3mm thick) to firmly bond the steel plate to the concrete cylinder surface. Place a 20mm thick steel ring plate (as an anchoring platform for subsequent connection nodes) evenly along the circumference of the cylinder's cross-section. Divide the cylinder into four sector-shaped areas (each sector 90°). Leave a 20-30mm gap at the boundary of each sector to avoid welding stress concentration. Use manual arc welding or gas shielded welding to spot weld the inner side of the steel ring plate to the outer side of the outer thick steel plate for positioning. Then, continuously weld along the circumference for fixation (weld height 8-10mm, meeting the secondary weld quality requirements). Install 8mm thick vertical stiffening ribs in sequence (one rib is set every 500-800mm along the vertical direction of the cylinder, and 4-8 ribs are evenly distributed along the circumference). Weld the inner side of the vertical stiffening ribs to the outer thick steel plate (weld height 6-8mm) and spot weld the outer side to the steel ring plate for temporary fixation, completing the preliminary assembly of the cylindrical outer steel component.
[0026] Step 2: Welding of node connection components. Place the 16mm thick longitudinal double connection plates (a pair of parallel thick steel plates, the length of which matches the height of the steel beam web, and the width which covers the connection range of the steel beam flange) horizontally perpendicular to the axis of the new steel beam. Weld the outer side of the longitudinal double connection plates to the outer side of the steel ring plate (outer side of the four sector areas of the segment) to fix them in place (weld height 10-12mm, to ensure connection strength); check the quality of all welded parts (no porosity, slag inclusions, or lack of fusion defects). If necessary, perform ultrasonic testing on the welds. At this point, the installation of the steel structure connection components (including the outer thick steel plate, steel ring plate, vertical stiffening ribs, and longitudinal double connection plates) is completed.
[0027] Step 3: Binding and pouring of the enlarged cross-section reinforcement cage. The area on the surface of the existing concrete column requiring an enlarged cross-section is roughened a second time. After cleaning, the longitudinal reinforcement and stirrups for the enlarged cross-section are bound: 16mm diameter HRB400 grade longitudinal reinforcement bars are bent and anchored inside the existing concrete column (anchoring depth ≥ 15d, where d is the diameter of the reinforcement bar); 8mm diameter HRB400 grade stirrups (spaced 200mm) are wrapped around the outside of the longitudinal reinforcement bars and secured with wire (binding point spacing ≤ 200mm); after completing the reinforcement cage binding, high-performance grout (compressive strength ≥ 60MPa, fluidity ≥ 300mm, meeting the high density requirements of the joint area) is used to fill the enlarged cross-section area through pressure grouting or manual assisted pouring (wet the concrete column surface and apply an interface agent before pouring), forming an enlarged cross-section concrete layer (thickness typically 50–100mm) that is tightly bonded to the existing column. The layer is then cured to the design strength (≥ 75% of the design value before subsequent steel beam installation).
[0028] Step 4: Add a new steel beam hinged connection. Hoist the new steel beam to the design position and align its end with the longitudinal double connecting plate. Connect the web or connecting plate of the steel beam to the longitudinal double connecting plate using M20 high-strength bolts. During installation, control the bolts to only bear shear force (leave a 2-3mm gap between the end of the steel beam and the longitudinal double connecting plate to avoid transmitting bending moment). Finally, tighten the nuts to the design torque to complete the hinged connection between the new steel beam and the existing concrete column.
[0029] Step 5: Multi-directional steel beam plane adjustment. If it is a unidirectional steel beam connection, only one side of Step 4 needs to be completed. If it is a multi-directional (four-directional) steel beam connection, install the steel beams of the other three directions in the same way (evenly distributed at 90° with the already installed steel beams). During the installation process, use a level and theodolite to monitor the elevation and plane position of the top surface of each steel beam in real time. Use shims to make fine adjustments to ensure that the top surfaces of the four steel beams are on the same horizontal plane (height difference ≤ 2mm) and the plane projection is coplanar (deviation ≤ 3mm). Finally, complete the hinged connection construction of the entire node area.
[0030] Compared with existing technologies, the present invention has the following advantages: The present invention, through the synergistic operation of a composite structure consisting of an outer steel plate, an enlarged cross-section, and a hinged connection plate, achieves a reliable hinged connection between the steel beam and the column, meeting the load-bearing capacity requirements under normal use and seismic conditions, and avoiding the problems of altered stress patterns and stress concentration in the main structure caused by traditional rigid connections. Specific technical effects include the following:
[0031] 1. By using a 20mm thick outer steel plate and structural adhesive to wrap the existing concrete column, and combining it with a post-cast enlarged section concrete layer with enlarged longitudinal reinforcement and stirrups, the overall shear bearing capacity and bonding performance of the joint area can be significantly improved. This avoids the problem of damage to the original main reinforcement caused by large-area removal of concrete or deep drilling in traditional methods, and protects the integrity of the existing concrete column to the greatest extent.
[0032] 2. This invention forms a steel structure connection component by setting a thick steel ring plate and vertical stiffening ribs and welding them with longitudinal double connecting plates. Then, the newly added steel beam is hinged to the connection component by M20 high-strength bolts. This ensures that the node only transmits vertical shear force and not bending moment, which meets the mechanical requirements of the hinged node and avoids the problems of bending moment superposition and change of the stress mode of the main structure caused by traditional rigid connection. It conforms to the seismic design principle of strong column and weak beam.
[0033] 3. By optimizing the node structure and adopting a step-by-step construction process (installing steel components first, then pouring the enlarged cross-section layer, and finally connecting the steel beams), the amount of on-site welding work and construction difficulty can be significantly reduced, the construction cycle can be shortened, and problems such as concentrated heat-affected zones, difficulty in guaranteeing weld quality, and large amount of wet work caused by a large amount of on-site welding in traditional methods can be avoided. At the same time, the damage to the existing concrete columns caused by the new connection structure is minimized (only surface roughening and local steel bar bending are required), which improves construction safety and node reliability. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0035] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;
[0036] Figure 2 This is a cross-sectional view of AA in Embodiment 1 of the present invention;
[0037] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of the present invention;
[0038] Figure 4This is a cross-sectional view of BB in Embodiment 2 of the present invention.
[0039] In the picture:
[0040] 1. Existing concrete cylindrical column; 2. New steel beam; 3. Increased cross-section stirrups; 4. Increased cross-section longitudinal reinforcement; 5. Thick steel ring plate; 6. Vertical stiffening ribs; 7. Longitudinal double connecting plate; 8. High-strength bolts; 9. Outer thick steel plate. Detailed Implementation
[0041] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0042] As attached Figure 1 To be continued Figure 2 As shown:
[0043] Example 1: This invention provides a connection structure for hinged connection between a new steel beam 2 and an existing concrete column 1. The connection structure is configured as a composite structure that hinges the new steel beam 2 to the existing concrete column 1 and enhances the shear bearing capacity of the joint. This composite structure is arranged circumferentially along the existing concrete column 1 and is bonded to the column through a post-cast enlarged cross-section concrete layer. The composite structure includes an outer thick steel plate 9, longitudinal double connecting plates 7, a thick steel ring plate 5, vertical stiffening ribs 6, enlarged cross-section longitudinal reinforcement 4, and the new steel beam 2, wherein:
[0044] The outer thick steel plate 9 is wrapped around the outer surface of the existing concrete cylinder 1. The thickness is 20mm and it is tightly bonded to the surface of the existing concrete cylinder 1 with structural adhesive. It is continuously set along the vertical full height of the existing concrete cylinder 1 and is coaxial with the existing concrete cylinder 1. The outer thick steel plate 9 is provided with a fixed thick steel ring plate 5 and vertical stiffening ribs 6.
[0045] The longitudinal double connecting plate 7 is a pair of parallel thick steel plates and welded to the thick steel ring plate 5. The thickness of the longitudinal double connecting plate 7 is 16mm. The longitudinal double connecting plate 7 is perpendicular to the horizontal direction of the axis of the new steel beam 2 and is connected to the end of the new steel beam 2 through M20 high-strength bolts 8 to form a hinged force transmission path between the new steel beam 2 and the concrete column.
[0046] Thick steel ring plate 5 is located in the middle of the outer thick steel plate 9 near the top or bottom of the existing concrete cylinder 1 in the connection area. Its thickness is 20mm. It is evenly segmented along the circumferential direction of the cross-section of the existing concrete cylinder 1 (divided into 4 fan-shaped areas). Its inner side is welded to the outer thick steel plate 9, and its outer side is connected to the longitudinal double connecting plate 7 by high-strength bolts 8. Thick steel ring plate 5 is used to provide local stability of the connection part and bolt anchoring platform.
[0047] The vertical stiffening rib 6 is a vertical steel plate that is spaced vertically along the existing concrete cylinder 1. It is 8mm thick. Its inner side is welded to the outer thick steel plate 9, and its outer side is connected to the thick steel ring plate 5. The vertical stiffening rib 6 is used to enhance the lateral stiffness and overall stability of the connection node.
[0048] The enlarged section concrete layer is a rough bonding surface formed by surface roughening of the existing concrete cylinder 1. It is formed by post-pouring grout. The enlarged section concrete layer wraps the enlarged section longitudinal reinforcement 4 and the enlarged section stirrup 3. The enlarged section concrete layer has a circular structure. The enlarged section longitudinal reinforcement 4 is arranged in a ring around the perimeter of the existing concrete cylinder 1. The enlarged section stirrup 3 is arranged in a ring. At this time, the entire node area has a cylindrical haunch structure.
[0049] The longitudinal reinforcement 4 of the enlarged section is HRB400 grade steel bar with a diameter of 16mm and a spacing of 200mm. The longitudinal reinforcement 4 of the enlarged section is arranged in a ring around the perimeter of the existing concrete column 1 and is anchored inside the enlarged section concrete layer (anchorage depth ≥15d). The longitudinal reinforcement 4 of the enlarged section is used to bear the main shear resistance of the joint area and provide longitudinal reinforcement.
[0050] The enlarged section stirrup 3 is an HRB400 grade steel bar with a diameter of 8mm and a spacing of 200mm. The enlarged section stirrup 3 surrounds the outside of the enlarged section longitudinal reinforcement 4. The enlarged section stirrup 3 is used to restrain the enlarged section concrete layer and improve the compressive strength of the concrete in the joint area. After being tied and fixed together with the enlarged section longitudinal reinforcement 4, it forms the enlarged section area.
[0051] Working principle: In Example 1, the existing concrete column 1 is wrapped with a 20mm thick steel plate and bonded with structural adhesive to form a foundation shear layer. The shear bearing capacity of the joint is enhanced by the post-cast enlarged section concrete layer with increased cross-section longitudinal reinforcement 4 and stirrups. The newly added steel beam 2 is hinged to the longitudinal double connecting plate 7 with M20 high-strength bolts 8. The longitudinal and transverse forces are transmitted through the connecting plate to the thick steel ring plate 5, vertical stiffening ribs 6 and the outer steel plate. Finally, the composite structure diffuses the forces to the original column (existing concrete column 1 / original concrete column), realizing the function of the hinged joint that only transmits vertical shear force, while avoiding large-area damage to the original column and facilitating construction.
[0052] As attached Figure 3 To be continued Figure 4 As shown:
[0053] Example 2: This example is basically the same as the previous example, except that the enlarged section concrete layer is a square structure, the enlarged section longitudinal reinforcement 4 is distributed rectangularly around the existing concrete column (non-circular arrangement), and the enlarged section stirrups 3 are set in a rectangular or square shape (matching the arrangement of longitudinal reinforcement). At this time, the entire node area is a square haunch structure. At the same time, if it is difficult to install reinforcement in the enlarged section of the column head, it can be changed to a square section structure.
[0054] The method for hinged connection between the newly added steel beam and the existing concrete column in Embodiments 1 and 2 includes the following steps:
[0055] Step 1: Surface treatment of the cylinder and installation of the outer steel plate (thick outer steel plate 9). First, determine the elevation and range of the new steel beam 2 to be added. Roughen the surface of the existing concrete cylinder 1 (using mechanical sandblasting or manual roughening to create a uniform, uneven, rough texture, increasing the subsequent bonding area), and clean the surface of dust and debris. Then, hoist the 20mm thick outer steel plate 9, continuously wrapping it along the entire vertical height of the cylinder and coaxial with the cylinder. Use structural adhesive (using high-strength epoxy structural adhesive, applied 2-3mm thick) to tightly bond the steel plate to the surface of the concrete cylinder. Place the 20mm thick steel ring plate 5 (as an anchoring platform for subsequent connection nodes) along the cross-section of the cylinder. The cylinder is evenly divided into four sector-shaped areas (each sector 90°). A 20-30mm gap is reserved at the boundary of each sector-shaped area to avoid welding stress concentration. The inner side of the steel ring plate is tack welded to the outer side of the outer thick steel plate 9 using manual arc welding or gas shielded welding. Then, it is continuously welded and fixed along the circumference (weld height 8-10mm, meeting the secondary weld quality requirements). 8mm thick vertical stiffening ribs 6 are installed in sequence (one is set every 500-800mm along the vertical direction of the cylinder, and 4-8 pieces are evenly distributed along the circumference). The inner side of the vertical stiffening ribs 6 is welded to the outer thick steel plate 9 (weld height 6-8mm), and the outer side is temporarily fixed to the steel ring plate by tack welding, completing the preliminary assembly of the cylindrical outer steel component.
[0056] Step 2: Welding of node connection components. Place the 16mm thick longitudinal double connection plate 7 (a pair of parallel thick steel plates, the length of which matches the height of the steel beam web and the width of which covers the connection range of the steel beam flange) horizontally perpendicular to the axis of the new steel beam 2. Weld the outer side of the longitudinal double connection plate 7 to the outer side of the steel ring plate (outer side of the four segmented fan-shaped areas) to fix it in place (weld height 10-12mm, to ensure connection strength). Check the quality of all welded parts (no porosity, slag inclusions, or lack of fusion defects). If necessary, perform ultrasonic testing on the welds. At this point, the installation of the steel structure connection components (including the outer thick steel plate 9, steel ring plate, vertical stiffening rib 6, and longitudinal double connection plate 7) is completed.
[0057] Step 3: Binding and pouring of the enlarged cross-section reinforcement cage. The area on the surface of the existing concrete column 1 requiring an enlarged cross-section is roughened a second time. After cleaning, the longitudinal reinforcement 4 and stirrups for the enlarged cross-section are bound: 16mm diameter HRB400 grade longitudinal reinforcement 4 is bent and anchored inside the existing concrete column 1 (anchoring depth ≥ 15d, where d is the diameter of the reinforcement); 8mm diameter HRB400 grade stirrups 3 (spaced 200mm) are wrapped around the outside of the longitudinal reinforcement and fixed with wire (binding point spacing ≤ 200mm); after completing the reinforcement cage binding, high-performance grout (compressive strength ≥ 60MPa, fluidity ≥ 300mm, meeting the high density requirements of the joint area) is used to fill the enlarged cross-section area through pressure grouting or manual assisted pouring (wet the concrete column surface and apply an interface agent before pouring), forming an enlarged cross-section concrete layer (thickness usually 50-100mm) that is tightly bonded to the existing column. The layer is then cured to the design strength (≥ 75% of the design value before subsequent steel beam installation).
[0058] Step 4: Add a new steel beam 2 for hinged connection. Hoist the new steel beam 2 to the design position and align its end with the longitudinal double connecting plate 7. Connect the web or connecting plate of the steel beam to the longitudinal double connecting plate 7 using M20 high-strength bolts 8. During installation, control the bolts to only bear shear force (leave a 2-3mm gap between the end of the steel beam and the longitudinal double connecting plate 7 to avoid transmitting bending moment). Finally, tighten the nuts to the design torque to complete the hinged connection between the new steel beam 2 and the existing concrete column 1.
[0059] Step 5: Multi-directional steel beam plane adjustment. If it is a unidirectional steel beam connection, only one side of Step 4 needs to be completed. If it is a multi-directional (four-directional) steel beam connection, install the steel beams of the other three directions in the same way (evenly distributed at 90° with the already installed steel beams). During the installation process, use a level and theodolite to monitor the elevation and plane position of the top surface of each steel beam in real time. Use shims to make fine adjustments to ensure that the top surfaces of the four steel beams are on the same horizontal plane (height difference ≤ 2mm) and the plane projection is coplanar (deviation ≤ 3mm). Finally, complete the hinged connection construction of the entire node area.
[0060] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A connection structure for hinged connection between a new steel beam and an existing concrete column, the connection structure being configured as a composite structure that hinges the new steel beam (2) and the existing concrete column (1) and enhances the shear bearing capacity of the joint, the composite structure being arranged circumferentially along the existing concrete column (1) and bonded to the column body through a post-cast enlarged cross-section concrete layer, characterized in that: The composite structure includes an outer thick steel plate (9), longitudinal double connecting plates (7), thick steel ring plates (5), vertical stiffening ribs (6), longitudinal reinforcement with increased cross-section (4), and newly added steel beams (2), wherein: The outer thick steel plate (9) is wrapped around the outer surface of the existing concrete column (1) with a thickness of 20mm and is tightly bonded to the surface of the existing concrete column (1) with structural adhesive. It is continuously set along the vertical full height of the existing concrete column (1) and is coaxial with the existing concrete column (1). The outer thick steel plate (9) is provided with a fixed thick steel ring plate (5) and vertical stiffening ribs (6). The longitudinal double connecting plate (7) is a pair of parallel thick steel plates and welded to the thick steel ring plate (5). The thickness of the longitudinal double connecting plate (7) is 16mm. The longitudinal double connecting plate (7) is perpendicular to the horizontal direction of the axis of the new steel beam (2) and is connected to the end of the new steel beam (2) by high-strength bolts (8) to form a hinged force transmission path between the new steel beam (2) and the concrete column. Thick steel ring plate (5) is located in the middle of the outer thick steel plate (9) near the top or bottom of the existing concrete cylinder (1) in the connection area. Its thickness is 20mm. It is evenly segmented along the circumferential direction of the cross section of the existing concrete cylinder (1). Its inner side is welded to the outer thick steel plate (9), and its outer side is connected to the longitudinal double connecting plate (7) by high-strength bolts (8). The vertical stiffening rib (6) is a vertical steel plate that is vertically spaced along the existing concrete column (1), with a thickness of 8mm. Its inner side is welded to the outer thick steel plate (9), and its outer side is connected to the thick steel ring plate (5). The enlarged section concrete layer is a rough bonding surface formed by surface roughening treatment of the surface of the existing concrete column (1), which is formed by post-pouring grout. The enlarged section concrete layer wraps the enlarged section longitudinal reinforcement (4) and the enlarged section stirrup (3). The longitudinal reinforcement (4) with enlarged cross section is arranged in a ring around the perimeter of the existing concrete column (1) and is anchored inside the concrete layer with enlarged cross section. The longitudinal reinforcement (4) with enlarged cross section is used to bear the main shear resistance of the joint area and provide longitudinal reinforcement. The increased cross-section stirrups (3) surround the increased cross-section longitudinal reinforcement (4). The increased cross-section stirrups (3) are used to restrain the increased cross-section concrete layer and improve the compressive strength of the concrete in the joint area. After being tied and fixed, they together form the increased cross-section area.
2. The connection structure for hinged connection between a new steel beam and an existing concrete column according to claim 1, characterized in that: The increased cross-section stirrups (3) are HRB400 grade steel bars with a diameter of 8mm and a spacing of 200mm.
3. The connection structure for hinged connection between a new steel beam and an existing concrete column according to claim 1, characterized in that: The longitudinal reinforcement (4) with increased cross-section is HRB400 grade steel bar with a diameter of 16mm and a spacing of 200mm.
4. A method for hinged connection between a newly added steel beam and an existing concrete column as described in any one of claims 1-3, characterized in that: Includes the following steps: Step 1: Surface treatment of the cylinder and installation of the outer steel plate. First, the elevation and range of the new steel beam (2) to be added are marked. The surface of the existing concrete cylinder (1) is roughened and the surface dust and debris are cleaned. Then, a 20mm thick outer steel plate (9) is hoisted and continuously wrapped along the vertical height of the cylinder and is coaxial with the cylinder. The steel plate is tightly bonded to the surface of the concrete cylinder by structural adhesive. The 20mm thick steel ring plate (5) is evenly divided into four fan-shaped areas along the circumferential direction of the cylinder cross section. A 20-30mm gap is reserved at the boundary of each fan-shaped area to avoid welding stress concentration. The inner side of the steel ring plate is spot welded to the outer side of the outer steel plate (9) by manual arc welding or gas shielded welding. Then, it is continuously welded and fixed along the circumferential direction. The 8mm thick vertical stiffening ribs (6) are installed in sequence. The inner side of the vertical stiffening ribs (6) is welded to the outer steel plate (9), and the outer side is spot welded to the steel ring plate for temporary fixation. The initial assembly of the outer steel components of the cylinder is completed. Step 2: Welding of node connection components. Place the 16mm thick longitudinal double connection plate (7) horizontally perpendicular to the axis of the newly added steel beam (2). Weld the outer side of the longitudinal double connection plate (7) to the outer side of the steel ring plate. Check the quality of all welded parts and perform ultrasonic testing on the welds. The steel structure connection components are now installed. Step 3: Binding and pouring of the reinforcing cage for enlarged cross-section. The area on the surface of the existing concrete column (1) that needs to be enlarged is roughened a second time. After cleaning, the longitudinal reinforcement (4) and stirrups for enlarged cross-section are bound together: the 16mm diameter HRB400 grade longitudinal reinforcement (4) for enlarged cross-section is bent and anchored inside the existing concrete column (1); the 8mm diameter HRB400 grade stirrups for enlarged cross-section (3) are wrapped around the outside of the longitudinal reinforcement and fixed with wire. After the reinforcing cage is bound together, high-performance grout is used to fill the enlarged cross-section area by pressure injection or manual assisted pouring to form an enlarged cross-section concrete layer that is tightly bonded to the existing column. The concrete is then cured to the design strength. Step 4: Add a new steel beam (2) and make a hinged connection. Hoist the new steel beam (2) to the design position and align its end with the longitudinal double connecting plate (7). Connect the web or connecting plate of the steel beam to the longitudinal double connecting plate (7) with high-strength bolts (8). During installation, control the bolts to only bear shear force. Finally, tighten the nuts to the design torque to complete the hinged connection between the new steel beam (2) and the existing concrete column (1). Step 5: Multi-directional steel beam plane adjustment. If it is a unidirectional steel beam connection, only step 4 on one side needs to be completed. If it is a four-directional steel beam connection, install the steel beams in the other three directions in the same way. During the installation process, use a level and a theodolite to monitor the elevation and plane position of the top surface of each steel beam in real time. Use shims to make fine adjustments to ensure that the top surfaces of the four steel beams are on the same horizontal plane and the plane projection is coplanar. Finally, complete the hinged connection construction of the entire node area.