A construction method for adding a shock isolation structure to an existing concrete frame column

Abstract

The application discloses a construction method for adding a shock insulation structure on an existing concrete frame column, and belongs to the technical field of building structure anti-seismic reinforcement. The method comprises the following steps: first, constructing an upper and lower bearing structure connected by a column cap and a pull beam above and below a predetermined cutting position of the existing frame column to form an integral support frame and a construction space; after setting a temporary steel support in the space, cutting the original column statically to form upper and lower column heads; then, constructing a support pier between the column heads and installing a shock insulation support; finally, performing load conversion through a jack, removing the temporary steel support, and smoothly transferring the load to the shock insulation support. The application solves the technical problems of smooth load conversion, reliable connection of new and old structures and precise implantation of shock insulation supports during local shock insulation reinforcement of the existing bearing column under the premise of slight disturbance by constructing a system of first fixation and then cutting and smooth support replacement, and is particularly suitable for improving the anti-seismic performance of existing structures such as historical buildings which need to be protected in the original state.

Description

Technical Field

[0001] This invention belongs to the field of seismic-resistant concrete construction, and in particular, it is a construction method for adding seismic isolation structures to existing concrete frame columns. Background Technology

[0002] Adding seismic isolation bearings to existing building structures, especially concrete frame columns, is a crucial and highly challenging issue in the current fields of urban renewal and historical building preservation. Many existing historical buildings and important public buildings, constructed in the early years of the People's Republic of China or even earlier, were not adequately designed and constructed with seismic fortification in mind, or had low seismic standards, and generally lack effective seismic isolation and damping measures. Over time, as material properties degrade, the vulnerability of these buildings to earthquakes becomes increasingly apparent, facing serious damage and even the risk of collapse. Many historical buildings not only bear important functional responsibilities but also possess irreplaceable cultural value and historical memory; demolition and reconstruction are not only uneconomical but also result in the permanent loss of cultural heritage. Therefore, how to improve the performance of buildings and incorporate modern seismic isolation technology while preserving their original appearance to the greatest extent possible and without affecting daily use has become a key issue that urgently needs to be addressed by the engineering community.

[0003] Traditional seismic isolation technology is mainly applied to new buildings, achieved by installing a seismic isolation layer between the foundation and the superstructure. However, for existing buildings, especially when focusing on seismic isolation reinforcement of only key load-bearing components such as concrete columns, a series of complex challenges arise: 1. Work must be carried out under or inside existing columns, and the construction space is usually limited; Second, the original columns need to be partially cut and the load transfer needs to be changed. During the process, it is necessary to ensure that the load transfer path of the superstructure is continuous and stable, and to strictly control settlement and deformation. Third, construction should minimize interference with the building's historical appearance, internal functions, and surrounding environment. Fourth, the newly added seismic isolation structure must have reliable durability, stable recovery capability, and effective connection with the original structure.

[0004] Therefore, there is an urgent need for a technology that can improve the seismic performance of existing concrete columns without affecting their original appearance and use, and can be used for local seismic isolation and reinforcement. Summary of the Invention

[0005] The purpose of this invention is to provide a construction method for adding seismic isolation structures to existing concrete frame columns. It aims to solve the technical problems of how to achieve reliable connection and coordinated operation between the old and new structures, how to achieve smooth transition and stable support of the stress system, how to achieve micro-disturbance construction to protect the building, and how to implant the seismic isolation structure and ensure its function within a limited space.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A construction method for adding seismic isolation structures to existing concrete frame columns, comprising the following steps: S1, Construction of new structural steps: Above and below the predetermined cutting positions of each existing frame column, construct upper and lower load-bearing structures respectively. The upper and lower load-bearing structures between adjacent existing frame columns are connected as a whole by upper and lower horizontal connection structures. The upper and lower load-bearing structures and the upper and lower horizontal connection structures surround the existing frame columns to form a construction space. S2, Temporary steel support procedure during construction: Within the construction space, a set of temporary steel supports is symmetrically installed between the upper and lower load-bearing structures; S3, Cutting existing frame columns: Within the construction space, cut the existing frame columns twice at the predetermined cutting positions to separate the column body into upper and lower column heads; S4, Installation steps for seismic isolation bearings: Install seismic isolation bearings between the upper and lower column heads formed by cutting, and fix the upper and lower parts of the seismic isolation bearings to the upper and lower load-bearing structures respectively. S5, using jacks for two support replacement steps: In the construction space, a set of jacks is set up symmetrically between the upper and lower load-bearing structures and the temporary steel supports. The temporary steel supports are removed by loading with jacks, and then the seismic isolation bearings are replaced by unloading with jacks.

[0007] S1 specifically includes the following steps: Detailed design: Based on the design drawings of the existing frame columns, clarify the axis number and elevation benchmark of each existing frame column, and refine the design of the new structure, including the new load-bearing structure composed of upper and lower column caps and upper and lower supports, as well as the upper and lower horizontal connection structure formed by upper and lower tie beams and seismic isolation bearings, and carry out the positioning and layout on site according to the layout drawing; S11, Construction column cap reinforcement: Simultaneously construct the upper column cap reinforcement and the lower column cap reinforcement around the existing frame column; S12, Construction tie beam longitudinal reinforcement: The upper and lower tie beams are set between adjacent existing frame columns, respectively connecting the adjacent upper column cap and the adjacent lower column cap. The longitudinal axis of the upper and lower tie beams is aligned with the longitudinal axis of the existing frame column. The reinforcement of the upper and lower tie beams includes the longitudinal reinforcement of the upper and lower tie beams. The longitudinal reinforcement of the upper and lower tie beams is fixedly connected to the reinforcement of the upper and lower column caps as a whole within the range of the upper and lower column caps. It penetrates the existing frame column within the range of the existing frame column, and the ends extend out of the side surface of the upper and lower column caps to form the connection end of the upper and lower beam reinforcement. S13, longitudinal reinforcement of construction support: the upper and lower support reinforcement includes the upper and lower support longitudinal reinforcement. The upper and lower support longitudinal reinforcement are respectively set at intervals around the existing frame column and fixedly connected to the corresponding upper and lower column cap reinforcement as a whole. The ends extend out of the bottom surface of the upper column cap or the top surface of the lower column cap to form the connection end of the upper and lower support longitudinal reinforcement. S14, pour concrete for the upper and lower column caps and upper and lower tie beams to form a construction space: the upper and lower tie beam reinforcement also includes upper and lower tie beam stirrups. First, the connection ends of two adjacent corresponding upper and lower beam reinforcements are fixedly connected as one unit by the upper and lower beam extension reinforcements. Then, the upper and lower tie beam stirrups are fixedly connected to complete the construction of all upper and lower tie beam reinforcements. Then, the upper and lower column caps and upper and lower tie beams are supported by an integrated formwork. High-strength grouting holes corresponding to the longitudinal reinforcements of the upper and lower supports are reserved in the upper column cap. Then, the concrete of the upper and lower column caps and upper and lower tie beams is poured as a whole to form the newly added upper and lower load-bearing structures and cured to the design strength. At this time, a construction space is formed between the newly added upper and lower load-bearing structures.

[0008] S2 specifically includes the following steps: Temporary steel supports are symmetrically arranged in the center of the construction space. The steel supports are height-adjustable supports and are located at the four corners of the upper and lower column caps or at the center of the edges of the upper and lower column caps. The top and bottom of the steel supports abut against the bottom surface of the upper column cap and the top surface of the lower column cap, respectively. Meanwhile, two displacement gauges are symmetrically arranged in the center of the construction space, located symmetrically between the upper and lower tie beams and near the upper and lower column caps, respectively. The top and bottom of the displacement gauges are in contact with the surfaces of the upper and lower tie beams, respectively.

[0009] S3 cutting is performed using a wire saw static cutting method within the construction space.

[0010] S4 specifically includes the following steps: S41, Lower positioning plate for construction support piers and seismic isolation bearings: The lower support reinforcement also includes lower support U-shaped reinforcement and lower support stirrups. The lower support U-shaped reinforcement is inverted and fixedly connected to the lower support longitudinal reinforcement connection end embedded in the lower support as a whole. The elevation of the lower support U-shaped reinforcement after connection is higher than the top surface elevation of the lower column head. Then the lower support stirrups are fixed on the outside of the lower support U-shaped reinforcement. Position the lower positioning plate of the seismic isolation bearing and fix the anchor bar at the bottom of the plate to the support reinforcement. Then, chisel the construction joint where the upper surface of the lower support and the lower column cap meet. Erect the formwork for the lower support pier, then pour high-strength grout and cure it. The upper surface of the lower positioning plate is flush with the upper surface of the lower support pier. According to the test results of the test block under the same conditions, after the compressive strength of the high-strength grout for the lower support pier is not less than 75% of the design strength, remove the formwork for the lower support pier. S42, Construction of seismic isolation bearings and upper positioning plates for seismic isolation bearings: Transport each seismic isolation bearing to the vicinity of the corresponding frame column, clean the lower support surface, unscrew the temporary connecting bolts, re-measure the elevation and plane position of the seismic isolation bearing after the seismic isolation bearing is in place, tighten the connecting bolts, and then install the upper positioning plate of the seismic isolation bearing. S43, Construction support pier: The upper support reinforcement also includes upper support U-shaped reinforcement and upper support stirrups. The upper support U-shaped reinforcement is fixedly connected to the upper support longitudinal reinforcement pre-embedded in the upper support as a whole. The elevation of the upper support U-shaped reinforcement after connection is lower than the bottom elevation of the lower column head. The upper positioning plate is fixedly connected to the upper support reinforcement, and then the upper support stirrups are fixed on the outside of the upper support U-shaped reinforcement. The construction joint where the lower surface of the upper support pier and the upper column cap meet is then chiseled. The upper support pier formwork is then erected, and high-strength grout is poured through the reserved pouring holes and cured. After pouring, the lower surface of the upper positioning plate is flush with the lower surface of the lower support pier. Once the upper support pier reaches the design strength, the upper support pier formwork is removed.

[0011] S5 specifically includes the following steps: S51, Install the jack: Jacks are arranged symmetrically with the steel supports within the construction space. That is, when the steel supports are located at the four corners of the upper and lower column caps, the jacks are located at the center of the edges of the upper and lower column caps. The top and bottom of the jacks abut against the bottom surface of the upper column cap and the top surface of the lower column cap, respectively. S52, Steel support removal: Use jacks to replace the supports, adjust the jack load until the force is stable, then symmetrically dismantle the steel supports, and move them to the next construction area after dismantling. S53, jacks are simultaneously unloaded and removed: After adjusting the jacks to unload and detach from the upper support, check the seismic isolation bearings. If there are no abnormalities, remove the jacks and move them to the next construction area. At this point, the construction of the seismic isolation structure is complete.

[0012] S3 specifically includes the following steps: S31. Based on the height h of the seismic isolation bearing, draw lines to locate the upper and lower cutting lines of the existing frame column. The distance between the upper cutting line and the surface of the lower column cap is ≥h+5mm, and the distance between the lower cutting line and the surface of the lower column cap is ≤5mm. S32, install wire saw cutting equipment and guide rail on the pull-down beam, install wire saw guide wheel on the upper part of the upper cutting line, and set up a temporary protective frame for the steel support without cutting between the inner side of the steel support and the outer side of the wire saw. S33, start the wire saw cutting equipment, first cut according to the lower cutting line, then cut according to the upper cutting line. When the existing frame column section is reduced to 1 / 4, reduce the cutting speed until the cut section separates from the original existing frame column.

[0013] In S5, the selection of jacks is determined based on the calculated axial force of the existing frame columns. The principle for calculating the axial force of the existing frame columns is to calculate it based on the sum of one dead load and one variable load, while ensuring that the jack equipment has a safety factor of not less than 2.

[0014] In S52, the loading is controlled by CNC equipment to control the hydraulic pressure. The maximum force value of the jack is calculated based on the pressure of the existing frame column. It is divided into ten levels of loading force value. Each time the load is increased by one level, the steel support is checked for loosening. When all the steel supports can be loosened, the jack loading is stopped and stabilized at the force value at this time. Then the steel support is removed.

[0015] After S33, the lower surface of the upper column head formed by cutting is chiseled flush with the lower surface of the upper column cap, and the upper surface of the lower column head formed by cutting is chiseled flush with the upper surface of the lower column cap.

[0016] Compared with the prior art, the present invention has the following features and beneficial effects: This invention establishes a multi-anchored connection system between the old and new structures. The upper and lower column cap reinforcements encircle the original frame columns, and longitudinal reinforcements in the tie beams penetrate the column body, creating a hooping and tying effect on the original frame columns, enhancing the integrity of the joint area. The upper and lower supports are welded to the subsequently constructed U-shaped reinforcements through pre-embedded longitudinal reinforcement connections, and then compacted using high-strength grout. This creates a high-strength, non-shrinkage vertical load-bearing interface between the new supports and the original column caps and columns, ensuring reliable axial force transmission. The upper and lower tie beams laterally connect the newly added structures to adjacent frame columns, forming a horizontal connection and compensating for potential local stiffness reduction due to single-column cutting. Multiple columns can work together to bear loads, improving the overall lateral stiffness and stability of the structure, thus solving the technical problem of how to achieve reliable connection and collaborative operation between the old and new structures.

[0017] This invention introduces a new load transfer system. First, a rigid U-shaped frame, formed by upper and lower column caps and tie beams penetrating the column, connects adjacent columns before cutting, initially dispersing and transferring the load, providing support for subsequent steel bracing. Second, during cutting, steel bracing is installed, and deformation is monitored in real time using displacement gauges to ensure a safe and controllable cutting process. Finally, load transfer is achieved synchronously using jacks arranged symmetrically to complement the steel bracing. The replacement steel bracing is loaded first, then unloaded, smoothly transferring the load to the seismic isolation bearings, realizing the transition from temporary steel bracing to permanent seismic isolation. The entire process involves minimal structural deformation, solving the technical problem of achieving a smooth transition and stable support of the load-bearing system.

[0018] This invention employs wire saw static cutting technology to cut the original frame columns, maximizing the protection of the original structure from damage. All new components are constructed within the construction space formed between the column caps, i.e., within the limited space surrounding the original columns, eliminating the need for large-scale demolition or disruption to the building's spatial layout. Load transfer is completed locally using pre-set supports and jacks, minimizing interference with other parts of the building and essentially not affecting its normal use in other areas during the same period. This invention solves the technical problem of achieving minimally disturbed construction while protecting the building.

[0019] To ensure the installation and operation of the seismic isolation structure, this invention pre-installs the lower or upper positioning plate of the seismic isolation bearing and fixes it to the reinforcing steel during the pier reinforcement binding stage. This ensures the precise planar position and elevation of the bearing connection surface. High-strength grout is then poured to fill the gap, ensuring the bearing base plate bears the load and subsequent load transfer. The cutting position is designed to reserve construction operation space according to the height of the seismic isolation bearing, providing conditions for the installation of the bearing, ensuring construction accuracy and quality, and solving the technical problem of how to implant the seismic isolation structure and ensure its function within a limited space.

[0020] This invention effectively isolates seismic forces by creating seismic isolation interfaces at specific locations within existing concrete columns. Its working principle is as follows: First, a temporary and permanent alternative force transmission system is constructed using rebar installation, new piers, and tie beams. Active load transfer is achieved using steel supports and hydraulic jacks, transferring the upper load from the original column to the new piers, ultimately guiding it to the seismic isolation bearings. This ensures continuous stress distribution during the force transmission path conversion, avoiding abrupt changes. Second, a localized seismic isolation layer is implanted, with high-performance seismic isolation bearings inserted into the column to attenuate the upward transmission of seismic energy. Finally, relying on the synergy and overall enhancement of the new and old structures, full-section rebar installation, U-shaped rebar welding, and high-strength grouting ensure reliable integration and shared load-bearing between the new piers, tie beams, and the original column. The tie beams strengthen the inter-column connection, compensate for local stiffness reduction, and ensure coordinated operation of the upper and lower structures of the seismic isolation layer.

[0021] This invention reduces the seismic load on the superstructure and extends the structure's natural vibration period by implanting seismic isolation bearings. Compared to traditional reinforcement methods that simply increase the cross-section or complete demolition and reconstruction, this invention only modifies key local components, reducing engineering costs, avoiding the expenses of excavating and transporting backfill soil and rebuilding the main structure, and minimizing economic losses caused by long-term building closures. The seismic isolation bearings have a design life of up to 50 years and are easy to inspect and maintain, reducing maintenance costs throughout the building's lifecycle. This invention significantly enhances the seismic safety reserves of existing buildings, especially valuable historical buildings, effectively extending their service life. It has significant practical implications and engineering value for promoting sustainable urban development and the preservation of historical and cultural heritage. Attached Figure Description

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the existing frame column 1 before the construction of this invention.

[0024] Figure 2 This is a schematic diagram of the structure of the newly added structural steel bars in step S2 of the present invention.

[0025] Figure 3 This is a schematic diagram of the newly added structural concrete after the completion of step S2 of the present invention.

[0026] Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure.

[0027] Figure 5 This is a schematic diagram of the steel support and displacement gauge after the construction of step S2 of the present invention.

[0028] Figure 6 yes Figure 5 A schematic diagram of the cross-sectional structure.

[0029] Figure 7 This is a schematic diagram of the structure of cutting the existing frame column in step S3 of the present invention.

[0030] Figure 8 yes Figure 7 A schematic diagram of the structure after cutting.

[0031] Figure 9 yes Figure 8 A schematic diagram of the cross-sectional structure.

[0032] Figure 10 This is a schematic diagram of the reinforcement of the lower support pier after the construction of step S4 of the present invention.

[0033] Figure 11 This is a structural schematic diagram of the lower support pier, lower positioning plate, and seismic isolation bearing after the completion of step S4 of the present invention.

[0034] Figure 12 yes Figure 11 A schematic diagram of the cross-sectional structure.

[0035] Figure 13 This is a schematic diagram of the reinforcement structure of the upper support pier after the construction of step S4 of the present invention.

[0036] Figure 14 This is a schematic diagram of the upper support pier after the construction of step S4 of the present invention.

[0037] Figure 15 This is a schematic diagram of the jack structure after step S5 of the present invention is completed.

[0038] Figure 16 yes Figure 15 A schematic diagram of the cross-sectional structure.

[0039] Figure 17 This is a schematic diagram of the structure after the steel support is removed in step S5 of the present invention.

[0040] Figure 18 yes Figure 17 A schematic diagram of the cross-sectional structure.

[0041] Figure 19 This is a schematic diagram of the jack after unloading in step S5 of the present invention.

[0042] Figure 20 yes Figure 19 A schematic diagram of the cross-sectional structure.

[0043] Figure 21 yes Figure 19 A schematic diagram of the connection structure between two adjacent existing frame columns.

[0044] Figure label: Original structure and cut parts 1 - Existing frame column, 11 - Pre-determined cutting position, 111 - Upper cutting line, 112 - Lower cutting line, 12 - Upper column head, 13 - Lower column head; New structure 2 - New structure; 21 - Upper column cap; 211 - Upper column cap reinforcement; 22 - Lower column cap; 221 - Lower column cap reinforcement; 23 - Upper tie beam; 231 - Upper tie beam longitudinal reinforcement; 232 - Upper tie beam stirrups; 233 - Upper beam reinforcement connection end; 234 - Upper beam extension reinforcement; 24 - Lower tie beam; 241 - Lower tie beam longitudinal reinforcement; 242 - Lower tie beam stirrups; 243 - Lower beam reinforcement connection end; 244 - Lower beam extension reinforcement; 25 - Upper support; 251 - Upper support longitudinal reinforcement; 252 - Upper support U-shaped reinforcement; 253 - Upper support stirrups; 26 - Lower support; 261 - Lower support longitudinal reinforcement; 262 - Lower support U-shaped reinforcement; 263 - Lower support stirrups; 27 - Construction space; 28 - Pouring hole; Seismic isolation bearing system 3 - Seismic isolation bearing, 31 - Upper positioning plate of seismic isolation bearing, 32 - Lower positioning plate of seismic isolation bearing, 33 - Anchor bar; Temporary steel supports and measurement system; 4 - Steel support, 5 - Jack, 6 - Displacement gauge; Construction interface 7 - Construction joint; Equipment and tools 10 - Wire saw cutting equipment, 101 - Guide rail, 102 - Wire saw guide wheel. Detailed Implementation

[0045] See the examples. Figure 1-21As shown, a construction method for adding a seismic isolation structure to an existing concrete frame column includes the following steps: S1, Construction of the new structure 2 steps: Above and below the predetermined cutting position 11 of each existing frame column 1, construct the upper and lower load-bearing structures to form an integral whole. The upper and lower load-bearing structures, as well as the upper horizontal connecting structure and the lower horizontal connecting structure, surround the existing frame column 1 to form a construction space 27.

[0046] S1 specifically includes the following steps: Detailed Design: Based on the design drawings of the existing frame columns 1, clarify the axis numbers and elevation benchmarks of each existing frame column 1, and refine the design of the new structure, including the new load-bearing structure composed of upper column caps 21, lower column caps 22, upper supports 25, and lower supports 26, as well as the horizontal connection structure formed by upper tie beams 23 and lower tie beams 24, and the seismic isolation bearings 3. On-site positioning and layout should be carried out according to the layout drawings. When laying out the actual construction, it is necessary to clarify the axis numbers, elevation benchmarks, key data of the dimensions of upper and lower column caps, upper and lower supports, upper and lower tie beams, and seismic isolation bearing components according to the detailed design drawings, and draw the layout drawings. S11, Construction column cap reinforcement: See Figure 1-2 As shown, the upper column cap reinforcement 211 and the lower column cap reinforcement 221 are constructed simultaneously around the existing frame column 1. S12, longitudinal reinforcement of construction tie beam: see Figure 2 As shown, the upper tie beam 23 and the lower tie beam 24 are set between adjacent existing frame columns 1, respectively connecting the adjacent upper column cap 21 and the adjacent lower column cap 22. The longitudinal axis of the upper tie beam 23 and the lower tie beam 24 is aligned with the longitudinal axis of the existing frame column 1. The upper and lower tie beams are reinforced with longitudinal bars 231 and 241. The longitudinal bars 231 and 241 are fixedly connected to the upper column cap reinforcement 211 and the lower column cap reinforcement 221 within the range of the upper column cap 21 and the lower column cap 22. They penetrate the existing frame column 1 within the range of the existing frame column 1, without cutting the longitudinal bars inside the existing frame column 1, and the ends extend out of the surface of the upper column cap 21 and the lower column cap 22 to form the upper beam reinforcement connection end 233 and the lower beam reinforcement connection end 243. S13, Longitudinal reinforcement of construction supports: See Figure 2 As shown, the upper and lower support reinforcements include upper support longitudinal reinforcement 251 and lower support longitudinal reinforcement 261. The upper support longitudinal reinforcement 251 and lower support longitudinal reinforcement 261 are respectively arranged at intervals around the existing frame column 1 and are fixedly connected to the corresponding upper column cap reinforcement 211 and lower column cap reinforcement 221 as a whole. The ends extend out of the bottom surface of the upper column cap 21 or the top surface of the lower column cap 22 to form the connection end of the upper support longitudinal reinforcement 251 and lower support longitudinal reinforcement 261. S14, see also Figure 3-4As shown, the concrete for the upper column cap 21, lower column cap 22, upper tie beam 23, and lower tie beam 24 is poured to form the construction space 27. The upper and lower tie beam reinforcement also includes upper tie beam stirrups 232 and lower tie beam stirrups 242. First, the adjacent corresponding upper tie beam reinforcement connection ends 233 and lower tie beam reinforcement connection ends 243 are fixedly connected as one unit by upper tie beam extension reinforcement 234 and lower tie beam extension reinforcement 244. Then, the upper tie beam stirrups 232 and lower tie beam stirrups 242 are fixedly connected to complete all the upper and lower tie beam reinforcement. The construction proceeds as follows: then, the upper column cap 21, lower column cap 22, upper tie beam 23, and lower tie beam 24 are supported by an integrated formwork, and high-strength grouting holes 28 corresponding to the longitudinal reinforcement 251 of the upper support and the longitudinal reinforcement 261 of the lower support are reserved in the upper column cap 21. Then, the concrete of the upper column cap 21, lower column cap 22, upper tie beam 23, and lower tie beam 24 is poured in an integrated manner to form the upper and lower newly added load-bearing structures and cured to reach the design strength. At this time, a construction space 27 is formed between the upper and lower newly added load-bearing structures.

[0047] S2, Temporary steel support for construction step 4: Within the construction space 27, a set of temporary steel supports 4 are symmetrically installed between the upper and lower load-bearing structures.

[0048] S2 specifically includes the following steps: See [link / details] Figure 5-6 As shown, temporary steel supports 4 are symmetrically arranged in the center of the construction space 27. The steel supports 4 are height-adjustable supports and are located at the four corners of the upper column cap 21 and the lower column cap 22 or at the center of the edge of the upper column cap 21 and the lower column cap 22. The top and bottom of the steel supports 4 abut against the bottom surface of the upper column cap 21 and the top surface of the lower column cap 22, respectively. Meanwhile, two displacement gauges 6 are symmetrically arranged in the center of the construction space 27, located symmetrically between the upper tie beam 23 and the lower tie beam 24 near the upper column cap 21 and the lower column cap 22, respectively. The top and bottom of the displacement gauges 6 are in contact with the surfaces of the upper tie beam 23 and the lower tie beam 24, respectively.

[0049] Four steel supports (4) are installed for ease of subsequent cutting of existing frame columns and installation of seismic isolation bearings. One steel support is placed at each of the four corners of the column cap. The diameter and wall thickness of the steel supports need to be calculated based on the axial force of the existing frame columns, simultaneously meeting strength and stability requirements, with a safety factor of 2. Displacement gauges (6) can also be placed diagonally on the column cap to measure and verify the displacement of the column cap during unloading. After the steel supports are installed, their axial position, diameter, wall thickness, and height are checked to ensure correct installation.

[0050] S3, Cutting existing frame column 1: Within the construction space 27, cut the existing frame column 1 twice at the predetermined cutting position 11 to separate the column into upper column head 12 and lower column head 13.

[0051] When cutting S3, a wire saw static cutting method is used within the construction space 27.

[0052] S3 specifically includes the following steps: S31, see also Figure 7-9 As shown, based on the height h of the seismic isolation bearing 3, the positions of the upper cutting line 111 and the lower cutting line 112 of the existing frame column 1 are drawn. The distance between the upper cutting line 111 and the surface of the lower column cap 22 is ≥h+5mm, and the distance between the lower cutting line 112 and the surface of the lower column cap 22 is ≤5mm. S32, a wire saw cutting device 10 and a guide rail 101 are installed on the pull-down beam 24, a wire saw guide wheel 102 is installed on the upper part of the upper cutting line 111, and a temporary protective door frame for the steel support 4 is erected between the inner side of the steel support 4 and the outer side of the wire saw, in order to protect the steel support from being cut by the wire saw.

[0053] S33, start the wire saw cutting equipment 10 and cut slowly and evenly along the predetermined cutting line. During the cutting process, closely monitor the equipment's operation and adjust the cutting parameters in a timely manner to ensure cutting quality and efficiency. First, cut according to the lower cutting line 112, monitoring displacement changes in real time. If any abnormality is found, stop the operation immediately and resume cutting after the problem is resolved. Then, cut according to the upper cutting line 111. When 1 / 4 of the existing frame column 1's cross-section remains, reduce the cutting speed until the cut section separates from the original existing frame column 1. The separated cut section is then crushed and transported to the spoil disposal site. After cutting, manually chisel the surface. After S33, chisel the lower surface of the upper column head 12 and the lower surface of the upper column cap 21 to avoid affecting the subsequent construction of the pier reinforcement. Chisel the upper surface of the lower column head 13 and the upper surface of the lower column cap 22 to make them flush. After chiseling, remove the slag from the groove and then fill the groove with grout.

[0054] S4, Steps for installing the seismic isolation bearing 3: Install the seismic isolation bearing 3 between the upper column head 12 and the lower column head 13 formed by cutting, and fix the upper and lower parts of the seismic isolation bearing 3 to the upper and lower load-bearing structures respectively.

[0055] S4 specifically includes the following steps: S41, see also Figure 10 As shown, the lower positioning plate 32 of the construction support 26 and the seismic isolation bearing 3: The lower support reinforcement 26 also includes a lower support U-shaped reinforcement 262 and a lower support stirrup 263. The lower support U-shaped reinforcement 262 is inverted and fixedly connected to the connection end of the lower support longitudinal reinforcement 261 embedded in the lower support 26. The elevation of the lower support U-shaped reinforcement 262 after connection is higher than the top surface elevation of the lower column head 13. Then, the lower support stirrup 263 is fixed on the outside of the lower support U-shaped reinforcement 262.

[0056] Position the lower positioning plate 32 of the seismic isolation bearing 3 and fix the anchor bar 33 at the bottom of the plate to the support bar. Then, chisel the construction joint 7 where the upper surface of the lower support 26 and the lower column cap 22 meet. Erect the formwork for the lower support pier, then pour the micro-expansion high-strength grout and cure it. The upper surface of the lower positioning plate 32 is flush with the upper surface of the lower support pier 26. According to the test results of the test block under the same conditions, after the compressive strength of the micro-expansion high-strength grout of the lower support pier 26 is not less than 75% of the design strength, remove the formwork for the lower support pier. S42, see also Figure 11-12 As shown, the seismic isolation bearing 3 and the upper positioning plate 31 of the seismic isolation bearing 3 are constructed: Each seismic isolation bearing 3 is transported to the vicinity of the corresponding frame column using a transport rail. A liftable forklift is used to transport the seismic isolation bearing to the lower support 26. The surface of the lower support 26 is cleaned, and the temporary connecting bolts of the lower positioning plate 32 are unscrewed. After the seismic isolation bearing 3 is in place, the elevation and plane position of the seismic isolation bearing 3 are re-measured. The elevation and plane position of the seismic isolation bearing are re-measured using a total station or level. The connecting bolts are tightened, and then the upper positioning plate 31 of the seismic isolation bearing 3 is installed. S43, see also Figure 13-14 As shown, the upper support pier is 25: The upper support reinforcement 25 also includes upper support U-shaped reinforcement 252 and upper support stirrup 253. The upper support U-shaped reinforcement 252 is fixedly connected to the connection end of the upper support longitudinal reinforcement 251 embedded in the upper support 25 as a whole. The elevation of the upper support U-shaped reinforcement 252 after connection is lower than the bottom elevation of the lower column head 13. The upper positioning plate 31 is fixedly connected to the upper support reinforcement 25, and then the upper support stirrup 253 is fixed on the outside of the upper support U-shaped reinforcement 252. Subsequently, the construction joint 7, where the lower surfaces of the upper support 25 and the upper column cap 21 meet, is chiseled. Then, the upper support formwork is erected, and micro-expansion high-strength grout is poured through the reserved pouring hole 28 and cured. After pouring, the lower surface of the upper positioning plate 31 is flush with the lower surface of the lower support 26. Once the upper support 25 reaches its design strength, the upper support formwork is removed. During the pouring of the micro-expansion high-strength grout for the upper support, it is necessary to prevent grout leakage caused by incomplete formwork sealing from affecting the flatness of its bottom surface.

[0057] S5, using jack 5 to perform two support replacement steps: In the construction space 27, a set of jacks 5 is set up symmetrically between the upper and lower load-bearing structures and the temporary steel support 4. The temporary steel support 4 is removed by loading the jacks 5 to replace the support, and then the seismic isolation bearing 3 is replaced by unloading the jacks 5.

[0058] S5 specifically includes the following steps: S51, see S51. Figure 15-16 As shown, install jack 5: In S5, the selection of jack 5 is determined based on the calculated axial force of the existing frame column 1. The principle for calculating the axial force of the existing frame column 1 is to calculate it according to the sum of one dead load and one variable load, while ensuring that the jack 5 equipment has a safety factor of not less than 2.

[0059] Within the construction space 27, jacks 5 are arranged symmetrically to complement the steel support 4. That is, when the steel support 4 is located at the four corners of the upper column cap 21 and the lower column cap 22, the jacks 5 are located at the center of the edges of the upper column cap 21 and the lower column cap 22. The top and bottom of the jacks 5 abut against the bottom surface of the upper column cap 21 and the top surface of the lower column cap 22, respectively. In this embodiment, two jacks are used according to the axial force of the existing frame column and are symmetrically installed in the middle position of each side of the support. If the axial force of the column is large, four jacks can be used.

[0060] S52, see S52. Figure 17-18 As shown, steel support 4 is removed: Use jack 5 to replace the support. Adjust the load on jack 5 until the force is stable. Then, symmetrically dismantle the steel support 4. After dismantling, move it to the next construction area. In S52, the loading is controlled by CNC equipment to control the hydraulic pressure. The maximum force value of jack 5 is calculated based on the pressure of the existing frame column 1. It is divided into ten loading force values. Every time the load of jack 5 increases by one level, the steel support 4 is checked for looseness. When all steel supports 4 can be loosened, the loading of jack 5 is paused and stabilized at the force value at this time. Then the steel support is removed.

[0061] S53, see also Figure 19-21 As shown, jack 5 is simultaneously unloaded and removed: The position and stability of the jacks are checked again, and the hydraulic equipment and oil circuits are checked to ensure they are operating normally. Synchronous unloading and debugging are then performed. Once conditions are met, unloading work begins. After adjusting jack 5 to unload and detach from the upper support 25, the seismic isolation bearing 3 is checked. After waiting half an hour, the condition of the seismic isolation bearing is checked again. If there are no abnormalities, jack 5 is removed and moved to the next construction area. At this point, the seismic isolation structure construction is complete.

Claims

1. A construction method for adding a seismic isolation structure to existing concrete frame columns, characterized in that, The construction steps include: S1, Construction of new structure (2) steps: Above and below the predetermined cutting position (11) of each existing frame column (1), construct the upper and lower load-bearing structures to form an integral whole. The upper and lower load-bearing structures and the upper and lower horizontal connection structures surround the existing frame column (1) to form a construction space (27). S2, Temporary steel support (4) Step: In the construction space (27), a set of temporary steel supports (4) are symmetrically set between the upper and lower load-bearing structures. S3, Cutting existing frame column (1) step: In the construction space (27), cut the existing frame column (1) twice at the predetermined cutting position (11) to separate the column into upper and lower column heads (12, 13). S4, Installation of seismic isolation bearing (3) Step: Install seismic isolation bearing (3) between the upper and lower column heads (12, 13) formed by cutting, and fix the upper and lower parts of the seismic isolation bearing (3) to the upper and lower load-bearing structures respectively. S5, use jacks (5) to perform two support replacement steps: in the construction space (27), a set of jacks (5) are set up symmetrically between the upper and lower load-bearing structures and the temporary steel support (4). Use jacks (5) to load and replace the temporary steel support (4), and then use jacks (5) to unload the replacement support and seismic isolation bearing (3).

2. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 1, characterized in that: S1 specifically includes the following steps: Detailed design: Based on the design drawings of the existing frame columns (1), clarify the axis number and elevation benchmark of each existing frame column (1), and detail the design of the new structure (2), including the upper and lower column caps (21, 22) and the upper and lower support piers (25, 26) forming the new load-bearing structure, as well as the horizontal connection structure formed by the upper and lower tie beams (23, 24), and the seismic isolation bearing (3), and perform on-site positioning and layout according to the layout diagram; S11, Construction column cap reinforcement: Simultaneously construct the upper column cap reinforcement (211) and the lower column cap reinforcement (221) around the existing frame column (1). S12, Construction tie beam longitudinal reinforcement: The upper and lower tie beams (23, 24) are set between adjacent existing frame columns (1), respectively connecting the adjacent upper column cap (21) and the adjacent lower column cap (22). The longitudinal axis of the upper and lower tie beams (23, 24) is aligned with the longitudinal axis of the existing frame column (1). The upper and lower tie beam reinforcement includes the upper and lower tie beam longitudinal reinforcement (231, 241). The upper and lower tie beam longitudinal reinforcement (231, 241) is fixedly connected to the upper and lower column cap reinforcement (211, 221) within the range of the upper and lower column caps (21, 22), penetrates the existing frame column (1) within the range of the existing frame column (1), and the ends extend out of the surface of the upper and lower column caps (21, 22) to form the upper and lower beam reinforcement connection ends (233, 243). S13, longitudinal reinforcement of construction support: the upper and lower support reinforcement includes upper and lower support longitudinal reinforcement (251, 261). The upper and lower support longitudinal reinforcement (251, 261) are respectively set around the existing frame column (1) at intervals and fixedly connected with the corresponding upper and lower column cap reinforcement (211, 221) as a whole. The ends extend out of the bottom surface of the upper column cap (21) or the top surface of the lower column cap (22) to form the connection end of the upper and lower support longitudinal reinforcement (251, 261). S14, pour concrete for the upper and lower column caps (21, 22) and the upper and lower tie beams (23, 24) to form a construction space (27): the upper and lower tie beam reinforcement also includes the upper and lower tie beam stirrups (232, 242). First, the two adjacent corresponding upper and lower tie beam reinforcement connection ends (233, 243) are fixedly connected as one unit by the upper and lower tie beam extension reinforcement (234, 244). Then, the upper and lower tie beam stirrups (232, 242) are fixedly connected to complete the construction of all upper and lower tie beam reinforcement. Then, the upper and lower column caps (21, 22) and the upper and lower tie beams (23, 24) are supported by an integrated formwork. High-strength grouting material pouring holes (28) corresponding to the longitudinal reinforcement (251, 261) of the upper and lower supports are reserved in the upper column cap (21). Then, the concrete of the upper and lower column caps (21, 22) and the upper and lower tie beams (23, 24) is poured in an integrated manner to form the upper and lower newly added load-bearing structures and cured to reach the design strength. At this time, a construction space (27) is formed between the upper and lower newly added load-bearing structures.

3. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 1, characterized in that: S2 specifically includes the following steps: Temporary steel supports (4) are symmetrically arranged in the center of the construction space (27). The steel supports (4) are height-adjustable supports, located at the four corners of the upper and lower column caps (21, 22) or at the center of the edge of the upper and lower column caps (21, 22). The top and bottom of the steel supports (4) abut against the bottom surface of the upper column cap (21) and the top surface of the lower column cap (22), respectively. Meanwhile, two displacement gauges (6) are symmetrically arranged in the center of the construction space (27), located at the symmetrical positions of the upper and lower column caps (21, 22) between the upper and lower tie beams (23, 24), respectively. The top and bottom of the displacement gauges (6) are in contact with the surfaces of the upper and lower tie beams (23, 24), respectively.

4. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 1, characterized in that: When cutting S3, a wire saw is used for static cutting within the construction space (27).

5. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 1, characterized in that: S4 specifically includes the following steps: S41, the lower positioning plate (32) of the construction support pier (26) and the seismic isolation bearing (3): The lower support reinforcement (26) also includes the lower support U-shaped reinforcement (262) and the lower support stirrup (263). The lower support U-shaped reinforcement (262) is inverted and fixedly connected to the lower support longitudinal reinforcement (261) embedded in the lower support (26) as a whole. The elevation of the lower support U-shaped reinforcement (262) after connection is higher than the top surface elevation of the lower column head (13). Then the lower support stirrup (263) is fixed on the outside of the lower support U-shaped reinforcement (262). Position the lower positioning plate (32) of the seismic isolation bearing (3) and fix the anchor bar (33) at the bottom of the plate to the support bar. Then, chisel the construction joint (7) where the lower support (26) and the upper surface of the lower column cap (22) meet. The formwork of the lower support pier is erected, and then high-strength grout is poured and cured. The upper surface of the lower positioning plate (32) is flush with the upper surface of the lower support pier (26). According to the test results of the test block under the same conditions, the formwork of the lower support pier is removed after the compressive strength of the high-strength grout of the lower support pier (26) is not less than 75% of the design strength. S42, construction of seismic isolation bearing (3) and upper positioning plate (31) of seismic isolation bearing (3): Each seismic isolation bearing (3) is transported to the vicinity of the corresponding frame column. The surface of the lower support (26) is cleaned, and the temporary connecting bolts are unscrewed. After the seismic isolation bearing (3) is in place, the elevation and plane position of the seismic isolation bearing (3) are re-measured, the connecting bolts are tightened, and then the upper positioning plate (31) of the seismic isolation bearing (3) is installed. S43, Construction support pier (25): The upper support reinforcement (25) also includes upper support U-shaped reinforcement (252) and upper support stirrup (253). The upper support U-shaped reinforcement (252) is fixedly connected to the upper support longitudinal reinforcement (251) embedded in the upper support (25) as a whole. The elevation of the upper support U-shaped reinforcement (252) after connection is lower than the bottom elevation of the lower column head (13). The upper positioning plate (31) is fixedly connected to the upper support reinforcement (25), and then the upper support stirrup (253) is fixed on the outside of the upper support U-shaped reinforcement (252). The construction joint (7) where the lower surface of the upper support (25) and the upper column cap (21) meet is chiseled. Then the upper support formwork is erected, and high-strength grout is poured through the reserved pouring hole (28) and cured. After pouring, the lower surface of the upper positioning plate (31) is flush with the lower surface of the lower support (26). When the strength of the upper support (25) reaches the design strength, the upper support formwork is removed.

6. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 1, characterized in that: S5 specifically includes the following steps: S51, Install jack (5): Jacks (5) are arranged symmetrically with steel supports (4) in the construction space (27). When the steel supports (4) are located at the four corners of the upper and lower column caps (21, 22), the jacks (5) are located at the center of the edge of the upper and lower column caps (21, 22). When the steel supports (4) are located at the center of the edge of the upper and lower column caps (21, 22), the jacks (5) are located at the four corners of the upper and lower column caps (21, 22). The top and bottom of the jacks (5) are respectively in contact with the bottom surface of the upper column cap (21) and the top surface of the lower column cap (22). S52, Steel support (4) removal: Use jacks (5) to replace the support, adjust the load of jacks (5) until the force is stable, then dismantle the steel support (4) symmetrically, and after dismantling, move it to the next construction area; S53, jack (5) is unloaded and removed simultaneously: After adjusting the jack (5) to unload and separate from the upper support (25), check the seismic isolation bearing (3). If there is no abnormality, remove the jack (5). After removal, move to the next construction area. At this time, the construction of the seismic isolation structure is completed.

7. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 4, characterized in that: S3 specifically includes the following steps: S31, according to the height h of the seismic isolation bearing (3), draw lines to locate the positions of the upper and lower cutting lines (111, 112) of the existing frame column (1). The distance between the upper cutting line (111) and the surface of the lower column cap (22) is ≥h+5mm, and the distance between the lower cutting line (112) and the surface of the lower column cap (22) is ≤5mm. S32, install the wire saw cutting device (10) and guide rail (101) on the pull-down beam (24), install the wire saw guide wheel (102) on the upper part of the upper cutting line (111), and erect a temporary protective door frame of the steel support (4) between the inner side of the steel support (4) and the outer side of the wire saw. S33, start the wire saw cutting device (10), first cut according to the lower cutting line (112), then cut according to the upper cutting line (111). When the column section of the existing frame column (1) is reduced to 1 / 4, reduce the cutting speed until the cut section is separated from the original existing frame column (1).

8. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 1 or 6, characterized in that: In S5, the selection of the jack (5) is determined based on the calculated axial force of the existing frame column (1). The principle of calculating the axial force of the existing frame column (1) is to calculate it according to the sum of one time the dead load and one time the variable load, while ensuring that the jack (5) equipment has a safety factor of not less than 2 times.

9. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 6, characterized in that: In S52, the loading is controlled by CNC equipment to control the hydraulic pressure. The maximum force value of the jack (5) is calculated based on the pressure of the existing frame column (1). It is divided into ten levels of loading force value. The jack (5) checks whether the steel support (4) is loose after each level of load is added. When all the steel supports (4) can be loosened, the jack (5) is suspended from loading and stabilized at the force value at this time. Then the steel support is removed.

10. The construction method for adding a seismic isolation structure to an existing concrete frame column according to claim 7, characterized in that: After S33, the lower surface of the upper column head (12) formed by cutting is chiseled flush with the lower surface of the upper column cap (21), and the upper surface of the lower column head (13) formed by cutting is chiseled flush with the upper surface of the lower column cap (22).

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