Method for intelligently monitoring unsupported prestressed tendon space bionic fish belly linear reinforcing transfer beam column disassembly

Abstract

The invention discloses an intelligent monitoring unsupported prestressed tendon space bionic fish belly linear reinforcing transfer beam column disassembling method. The method comprises the following steps that S1, a to-be-disassembled concrete column and a related structure are determined based on a structure drawing; s2, carrying out structural overall modeling calculation analysis by utilizing PKPM software, and determining a reinforcing mode of adopting external prestress in cooperation with section increase based on a calculation analysis result; s3, construction preparation is conducted; s4, other non-dismantled concrete columns which are coaxial with the to-be-dismantled concrete column are reinforced; s5, external prestressed tendons are installed and tensioned, and the external prestressed tendons are linearly arranged along the bionic fish belly of the beam bottom; s6, reinforcing the transfer beam by adopting a section increasing method; s7, the to-be-dismantled concrete column is subjected to segmented dismantling construction under the supporting-free condition; and S8, in the dismantling process of the to-be-dismantled concrete column, the mid-span displacement of the transfer beam, the stress change of the transfer beam and the change of the external prestressed tendon in the dismantling process are monitored in real time.

Description

Technical Field

[0001] This invention relates to the field of reinforcement and renovation technology for existing engineering structures, specifically to a method for dismantling columns in a spatially biomimetic fish-belly-shaped reinforcement and conversion beam with intelligent monitoring of unsupported prestressed tendons. Background Technology

[0002] With supply-side structural reforms, an increasing number of existing buildings are undergoing economic transformation and renovation. Some of these renovations aim to increase load-bearing capacity, while others are designed to enhance functionality. In many existing buildings, the column spacing is narrow, severely limiting functionality. Using a beam-supported column-removal method can perfectly solve this problem, not only meeting functional requirements but also improving spatial design and enhancing safety and stability.

[0003] The traditional method for removing columns from beams involves first erecting a load-bearing support frame for the beam segment requiring column removal. Then, the frame column is dismantled using static or dynamic methods, and the frame beam is reinforced using traditional strengthening methods such as increasing the cross-section, transforming the previously separate beam segments into a single unit. Once the reinforcement materials have reached the required strength, the load-bearing support frame is removed, completing the beam-column removal process. During monitoring, external detection equipment is frequently used to monitor structural deformation and infer the stress state of the structure.

[0004] For example, Chinese patent CN111472566A discloses a support device and method for beam-column replacement. This support device includes, from top to bottom, a double-web H-beam, a horizontally supporting H-beam, and jacks. This invention is simple to construct, reliable in quality, safe and controllable, and cost-effective. However, this solution relies on a physical support system of double-web H-beams and jacks, which requires a large amount of space and can obstruct construction access and normal building use.

[0005] Chinese patent CN112502471A discloses a method and structure for reinforcing a steel frame structure by modifying and removing columns, including the following steps: welding temporary steel brackets on both sides of the steel column to be removed, and setting jacks under the temporary steel brackets; adjusting the jacks to apply a pre-jacking force; cutting the steel column to be removed below the temporary steel brackets to form a cut; determining the lifting displacement of the steel column to be removed, and gradually increasing the load of the jacks to the preset value; inserting steel pads into the cut of the steel column to be removed to fix the steel column at the lifting position and prevent further downward displacement, and unloading the jacks; reinforcing the steel frame structure by welding and fixing the steel truss to the steel frame structure; and removing the steel column and steel beam to be removed located below the steel truss. This method not only solves the problems of high structural unloading requirements and difficulty in achieving large spaces and large spans in conventional methods, but also uses a small-volume steel truss reinforcement structure that is easy to transport and construct, saving on project costs. However, the patent uses a temporary steel bracket and jack support system, which still requires welding of temporary structures, and the jacks need to be applied in stages when lifting, which poses a high risk of manual control.

[0006] Chinese patent CN116220428A discloses a beam-supported column removal structure and its construction method, including the following steps: Rebar installation: increasing the cross-section of some columns and beams by one or more combinations of reinforcing frame columns, adding new columns, reinforcing frame beams, adding new beams, adding new slabs, and adding new frame columns; Formwork: calculating the formwork support load and preparing a formwork plan; Demolition: uniformly demolishing the frame columns, disconnecting each frame column at a certain depth each time. However, this patent uses a full-scale scaffolding support system throughout the entire construction process, hindering the normal use of the building, and lacks real-time deformation control during demolition. The temporary erection and dismantling of supports increases the construction period and cost.

[0007] Chinese patent CN119021502A discloses a construction method for reinforcing and renovating a large-span drag beam by removing columns, including the following steps: Step 1, determining the columns to be retained and the columns to be removed from the building to be renovated; Step 2, determining the reinforcement construction monitoring scheme, arranging displacement, stress, and strain monitoring markers, and collecting initial values; Step 3, increasing the size of the lower foundation of the retained columns for reinforcement, and adding a number of anchor static pressure piles to reinforce the foundation and form a foundation foundation. However, this patent still requires the erection of a full-span scaffolding support system and temporary supports with jacks and I-beams, which occupies a large space and does not mention intelligent monitoring, relying on manual measurement, which cannot perceive changes in internal forces in real time and is prone to causing sudden accidents. Summary of the Invention

[0008] The purpose of this invention is to provide a method for intelligently monitoring and dismantling columns of unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced conversion beams. The technical problems to be solved are: First, it requires the construction of a physical support system, which occupies a lot of space and will obstruct construction access and normal building use; Second, it does not have intelligent real-time monitoring and adjustment, relies on manual measurement, cannot perceive changes in internal forces in real time, and is prone to sudden accidents.

[0009] To achieve the above objectives, this invention provides a method for intelligently monitoring and dismantling columns in unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beams, comprising the following steps: S1. Determine the concrete columns to be demolished and related structures based on the structural drawings; S2. Use PKPM software to perform overall structural modeling, calculation and analysis, and determine the reinforcement method of external prestressing combined with increasing the cross section based on the calculation and analysis results; S3. Construction preparation: Lay out and position the external prestressing tendons according to the design drawings; S4. Reinforce other concrete columns that are not to be demolished and are on the same axis as the concrete column to be demolished; S5. Installation and tensioning of external prestressing tendons: The external prestressing tendons are arranged in a biomimetic fish belly shape along the bottom of the beam. S6. The transfer beam is reinforced by increasing the cross-section. S7. Segmented demolition of concrete columns to be demolished under unsupported conditions. S8. During the demolition of the concrete column to be demolished, monitor in real time the mid-span displacement of the transfer beam, the stress change of the transfer beam, and the changes of the external prestressing tendons during the column demolition.

[0010] In a preferred embodiment, step S2 involves performing overall structural modeling and calculation analysis using PKPM software, including: S211. Establish an unreinforced structural model according to the original structural drawings. According to the requirements of the new function, apply new loads to the structure and calculate and analyze to obtain the reinforcement area required for the unreinforced structure to meet the bearing capacity and service requirements. At the same time, determine whether the original cross section of the structure meets the bearing capacity requirements. If it does not meet the requirements, the cross section needs to be increased for reinforcement. S212. Based on the calculation results of the unreinforced structural model, establish the first reinforced structural model. In the first reinforced structural model, increase the original beam cross-section to a transfer beam cross-section and increase the original column cross-section. Perform calculation and analysis on the first reinforced structural model to determine whether the added cross-section meets the bearing capacity requirements. S213. Based on the first reinforced structural model, nodal forces are added to simulate the effect of external prestressing tendons on the structure. At the same time, one concrete column in the middle is removed to form a second reinforced structural model. After removing one column, the span of the transfer beam changes from the original 4m span to 8m span. The second reinforced structural model is calculated and analyzed to determine whether the bearing capacity and deflection of the transfer beam meet the requirements after applying prestress and removing one concrete column. S214. Based on the second reinforced structure model, remove another concrete column and change the span of the transfer beam from 8m to 12m to form the third reinforced structure model. Perform calculation and analysis on the third reinforced structure model to check whether the bearing capacity of the beam and column meets the requirements and whether the deflection of the transfer beam meets the requirements. S215. Use the masonry reinforcement module for calculation and analysis. The calculation and analysis process shall be carried out in accordance with the requirements of steps S211 to S214. S216. Compare the calculation results of the concrete structure module and the masonry reinforcement module in PKPM, and take the maximum value of the two reinforcement calculation results for reinforcement treatment.

[0011] In a preferred embodiment, step S2, determining the reinforcement method of using external prestressing combined with increasing the cross-section, includes: S221. For the four adjacent concrete columns on the same axis as the two concrete columns to be demolished in the middle, the cross-section should be increased for reinforcement. S222. External prestressing tendons are used for reinforcement. There are two bundles of external prestressing tendons. The two bundles of external prestressing tendons are set on the bottom surface of the original beam, and the distance between the two bundles of external prestressing tendons is less than or equal to the width of the original beam. Each bundle of external prestressing tendons includes three unbonded steel strands, one of which is a smart steel strand. The smart steel strand has an optical fiber in its center, which can read the stress change of the external prestressing tendon. The optical signal is converted into an electrical signal to further read the prestress strain. The prestressing tensioning end is set at the two concrete columns adjacent to the concrete column to be demolished, on the outside of the beam end perpendicular to the transfer beam. The beam end is drilled with a water drill to allow the external prestressing tendon to pass through and is anchored on one side of the beam end. S223. The transfer beam is reinforced by increasing the cross-section.

[0012] In a preferred embodiment, step S5, the installation and tensioning of the external prestressing tendons, wherein the external prestressing tendons are arranged in a biomimetic fish-belly shape along the bottom of the beam, includes: S51. According to the arrangement of the external prestressing tendons and the steel strands, cut the materials first, install the steel hanging rods, and drill 80mm diameter holes with a water drill at 290mm from the end of the beam and 280mm from the bottom of the slab to reinforce the transfer beam. S52. Install the universal joint conversion support mechanism, and detect the position of the original steel bars in the beam during installation; S53, Inserted external prestressing tendons; S54. Pre-tension the external prestressing tendons; S55. Tension the external prestressing tendons to the design required force value.

[0013] In a preferred embodiment, step S55, tensioning the external prestressing tendons to the design required force value, includes: symmetrically tensioning two bundles of external prestressing tendons in stages, with the tension control stress taken as 50% of the standard value of the tensile ultimate strength of the prestressing tendons, and tensioning in four stages: 0.3, 0.6, 0.9, and 1.0. The corresponding tension forces for each external prestressing tendon are 39.06kN, 78.12kN, 117.18kN, and 130.2kN, respectively. During each stage of tensioning, all steel strands must complete one stage of tensioning before proceeding to the next stage.

[0014] In a preferred embodiment, step S6 involves reinforcing the transfer beam by increasing its cross-section, including: treating the interface of the original component, wherein the surface unevenness of the transfer beam is not less than 6mm, and grooves are chiseled at regular intervals on the casting surface of the original component to form shear keys, and the surface is roughened or grooved, with a groove depth of not less than 6mm and a spacing not greater than the stirrup spacing or 200mm, and a concrete interface binder is used when pouring new concrete.

[0015] In a preferred embodiment, step S7 involves segmented demolition of the unsupported concrete column, including: S71. Erect a protective frame. The frame shall be erected within a 4m radius of the concrete columns to be demolished, extending to the bottom of the slab, and forming a U-shaped structure on the outside of the two concrete columns to be demolished. S72. Cut the connection between the concrete column to be demolished and the structure, including: S721. Fix the track of the wire saw's power wheel at a position 1m above the ground at the first concrete column to be demolished; S722. Draw a horizontal line at the top of the concrete column to be demolished, 50mm from the bottom of the beam, as the horizontal line for cutting; S723. Install two steering pulleys at the horizontal line 50mm above the top of the concrete column to be demolished, so that the wire saw can be steered; S724. Start the wire saw to begin trial cutting; S725. During the cutting process, after the wire saw has cut to a depth of about 100mm, stop cutting, turn off the power to the wire saw, and insert a steel wedge into the cutting gap for the first time. When the cutting depth reaches 200mm, stop cutting, turn off the power to the wire saw, and insert a steel wedge into the cutting gap for the second time; S726. After cutting is completed, turn off the power to the wire saw, let it stand for 1 hour, and then begin disassembling the equipment; S727. Repeat steps S721-S726 for the second concrete column to be demolished. S73. Cut and break the two concrete columns to be demolished in sections.

[0016] In a preferred embodiment, step S73, segmentally cutting and breaking the two concrete columns to be demolished, includes: S731. Insert chemical anchors into the transfer beam, fix the chain hoist, and divide the concrete column to be demolished from top to bottom into sections of 200mm each, with the top section being the first section, and so on, until the bottom of the column. S732. An anchor bolt is inserted in the middle of the first section and connected to the chain hoist hook with a closing hook to tension the chain hoist. S733. Before cutting begins, prepare wooden blocks. If there is an emergency during the cutting process, insert wooden blocks to hold them in place. S734. Start cutting the first section. The first step has already used a wire saw to cut the top of the column from the structure. After the cutting is completed, use a water drill to disconnect the first section from the lower column. S735. After cutting, use a chain hoist to slowly and steadily place the first section on the ground; S736. Cut the second section. First, insert an anchor bolt in the middle of the second section. Connect the closing hook to the chain hoist hook. Tension the chain hoist. After cutting, use the chain hoist to slowly and steadily place the second section on the ground. Remove it in sequence. S737. Break up the dismantled column segments and remove them, completing the cutting and breaking of the first concrete column to be demolished. S738. Cut and break another concrete column to be demolished in the same order.

[0017] In a preferred embodiment, step S8 involves real-time monitoring of the mid-span displacement of the transfer beam, the stress change of the transfer beam, and the changes of the prestressed steel strands during the demolition of the concrete column. This includes: S81. Three stress monitoring points are set at intervals at the bottom mid-span of the transfer beam to monitor the stress changes of the beam. S82. Three deflection monitoring points are set at intervals at the mid-span of the transfer beam to monitor the mid-span displacement of the beam. Two horizontal displacement monitoring points are set at the top of the two concrete columns adjacent to the concrete column to be demolished to monitor the horizontal displacement of the structure during the demolition of the concrete column. S83. Use intelligent steel strands to monitor the stress changes of prestressed tendons before, during and after column dismantling.

[0018] In a preferred embodiment, the universal transfer support mechanism is fixed to both sides of the concrete column to be demolished with anchor bolts. Steel hanging rods are installed on the inner sides of the two concrete columns adjacent to the concrete column to be demolished. The steel hanging rods are located 290mm from the inner side of the beam end and 280mm from the bottom of the slab, and penetrate through the transfer beam. One end of the external prestressing tendon is installed at the fixed end using an extrusion anchor, and the other end is installed at the tensioning end using a wedge anchor. When tensioning the external prestressing tendon, since the external prestressing tendon is a spatial biomimetic fish belly shape rather than a planar line shape, it adapts to the angle through the universal transfer support mechanism to avoid bending the prestressing tendon and transmit the lifting force to the transfer beam.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses biomimetic fish-belly-shaped prestressed tendons and a universal conversion support mechanism to enable the prestressed tendons to adapt to the angle and effectively transmit the lifting force provided by the prestressed tendons to the structure. During the reinforcement and renovation process, no separate support (such as full-span scaffolding) is required, which can save space, avoid construction interference, increase safety, reduce the loss of internal force of the prestressed tendons and avoid bending of the prestressed tendons.

[0020] 2. This invention, by setting up intelligent steel strands, can monitor changes in prestressed tendon values ​​in real time and provide feedback for construction, thus ensuring subsequent safety warnings. It also monitors beam and column stress in real time by setting up fiber optic grating sensors and tracks mid-span deflection of conversion beams by setting up video displacement meters, thereby achieving multi-dimensional intelligent monitoring.

[0021] 3. Unlike traditional passive reinforcement using prestressing for post-reinforcement strengthening, the prestressing tendons of this invention are tensioned before column removal, actively offsetting the dead load and reducing the risk of beam deformation. The lifting force provided by the prestressing tendons can serve as the deflection recovery force for the transfer beam in the later stages. After the concrete columns are removed, the span of the transfer beam changes from 4m to 12m. Under the action of dead loads, live loads, and other loads, the deflection of the transfer beam will increase, leading to larger cracks. Now, the spatial biomimetic fish-belly-shaped prestressing tendons provide lifting force for the transfer beam, which can reduce the deflection of the transfer beam and turn the lifting force into a deflection recovery force. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the overall structure of the present invention; Figure 3 This is an elevation view of the external prestressing tendons of the present invention arranged in a biomimetic fish belly shape along the bottom space of the beam; Figure 4 for Figure 3 A schematic diagram along the AA direction; Figure 5 for Figure 3A schematic diagram along the BB direction; Figure 6 This is a schematic diagram of the universal conversion support mechanism of the present invention; Figure 7 for Figure 6 A schematic diagram along the CC direction; Figure 8 Schematic diagram for setting up a protective frame; Figure 9 This is a schematic diagram of the elevation cut by a wire saw. Figure 10 A schematic diagram of the concrete column facade to be demolished in sections; Figure 11 This is a schematic diagram of the construction monitoring points. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0024] The following describes the method of this invention in detail using an actual demolition and alteration project as an example. The demolition and alteration project involved a one-story structure above ground, with a two-story lobby section. There was no basement. The structure was a brick-concrete structure with a partial internal frame. The load-bearing exterior and interior walls were 360mm thick, the sintered bricks were designed to a strength grade of MU15, the mortar was designed to a strength grade of M5.0, and the floor and roof slabs were made of cast-in-place hollow concrete slabs with a thickness of 120mm. The test and evaluation report estimated the concrete strength as follows: the estimated compressive strength of the original structural columns on the first and second floors was 20.0MPa; the estimated compressive strength of the original structural beams on the first and second floors was 20.8MPa.

[0025] like Figures 1 to 11 As shown, the preferred embodiment of the present invention provides a method for intelligently monitoring and dismantling columns of unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beams, comprising the following steps: Step S1: Determine the concrete columns and related structures to be demolished based on the structural drawings. In order to meet the owner's needs and achieve the display effect in the building's function, it was determined that two concrete columns in the middle of the first-floor lobby need to be demolished. The original structural beam section was 250x650mm, and the column section was a circle with a diameter of 420mm.

[0026] Step S2: Use PKPM software to perform overall structural modeling, calculation and analysis, and determine the reinforcement method of external prestressing combined with increasing the cross section based on the calculation and analysis results.

[0027] Due to the complexity of the structure, which incorporates both masonry and concrete elements, the exterior walls and some interior walls are brick masonry, while the interior also includes concrete beam-slab-column structures. In this case, simply using the masonry module in PKPM to calculate the structure will not yield accurate results. Therefore, both the concrete structure module and the masonry module in PKPM are used for modeling and calculation. Specifically, the overall structural modeling, calculation, and analysis are performed using PKPM software, including: Step S211: Establish an unreinforced structural model according to the original structural drawings. According to the requirements of the new function, apply new loads to the structure and perform calculations and analyses to obtain the reinforcement area required for the unreinforced structure to meet the bearing capacity and usage requirements. At the same time, determine whether the original cross-section of the structure meets the bearing capacity requirements. If it does not meet the requirements, the cross-section needs to be increased for reinforcement.

[0028] Step S212: Based on the calculation results of the unreinforced structural model, establish the first reinforced structural model. In the first reinforced structural model, the original beam cross-section is increased to a transfer beam cross-section, and the original column cross-section is also increased. Besides adding the buttress columns, the main focus is on the calculation process of the central hall support beam and column removal. That is, the original beam cross-section of 250x650mm is modified to the transfer beam cross-section in the hall location, which is changed from the original 650x1000mm. The concrete strength is considered according to C17. The original column cross-section is modified from 420mm to 700mm, and the strength is considered according to C17. The first reinforced structural model is then calculated and analyzed to determine whether the added cross-sections meet the bearing capacity requirements.

[0029] Step S213: Based on the first reinforced structure model, add nodal forces to simulate the effect of external prestressing tendons on the structure. At the same time, remove one concrete column to be demolished in the middle to form the second reinforced structure model. After removing one concrete column to be demolished, the span of the transfer beam changes from the original 4m span to 8m span. Perform calculation and analysis on the second reinforced structure model to determine whether the bearing capacity and deflection of the transfer beam meet the requirements after applying prestress and removing one concrete column to be demolished.

[0030] Step S214: Based on the second reinforced structure model, remove another concrete column to be demolished, and change the span of the transfer beam from 8m to 12m to form the third reinforced structure model. Perform calculation and analysis on the third reinforced structure model to check whether the bearing capacity of the beam and column meets the requirements and whether the deflection of the transfer beam meets the requirements.

[0031] Step S215: Perform calculation and analysis using the masonry reinforcement module. The calculation and analysis process shall be carried out in accordance with the requirements of steps S211 to S214.

[0032] Step S216: Compare the calculation results of the concrete structure module and the masonry reinforcement module in PKPM, and take the maximum value of the two reinforcement calculation results for reinforcement treatment.

[0033] Calculations determined that an external prestressing method combined with increased cross-section reinforcement would be adopted, including: Step S221: For the four adjacent concrete columns 2 on the same axis as the two middle concrete columns 1 to be demolished, the cross-section is increased to strengthen them. The original cross-section is 420mm, and now it is increased to 700mm.

[0034] Step S222: Reinforcement is carried out using external prestressing tendons 3. The external prestressing tendons 3 consist of two bundles, which are placed on the bottom surface of the original beam. The distance between the two bundles of external prestressing tendons is less than or equal to the width of the original beam. Each bundle of external prestressing tendons 3 includes three unbonded steel strands, one of which is a smart steel strand. The smart steel strand has an optical fiber in its center, which can read the stress change of the external prestressing tendon. The optical signal is converted into an electrical signal to further read the prestress strain. The prestressing tensioning end 31 is set at the two concrete columns adjacent to the concrete column to be demolished, on the outside of the beam end 41 perpendicular to the transfer beam 3. The beam end 41 is drilled with a water drill to allow the external prestressing tendon to pass through, and it is anchored on one side of the beam end 41.

[0035] Step S223: Reinforce the transfer beam using the cross-section enlargement method. Since the surface finish at the top elevation of the transfer beam cannot be damaged, stirrups are inserted through the beam at the bottom of the slab. Holes are drilled 50mm from the bottom of the slab using an electric hammer, with a depth equal to the beam width. After cleaning the holes, horizontal stirrups are inserted through the concrete beam, ensuring the lengths of the horizontal stirrups on both sides of the beam are symmetrical and equal. Holes are drilled on the sides and bottom of the beam using an electric hammer, with a depth of 120mm and a spacing of 200mm, and tie bars are then inserted. U-shaped stirrups are used at the bottom and lapped with the horizontal stirrups, with a weld length of 50mm on both sides. New upper and lower longitudinal reinforcement bars are tied and inserted through the concrete column and the beams on both sides of the column.

[0036] Step S3: Prepare for construction: Lay out and position the external prestressing tendons according to the design drawings.

[0037] Step S4: Reinforce the other concrete columns 2 that are not to be demolished and are on the same axis as the concrete column 1 to be demolished. Specifically, the original cross-section of the concrete column 2 was 420mm, which is now increased to 700mm. First, excavate to the original foundation elevation, and then install and tie the reinforcing bars according to the drawings. Roughen the base layer of the column surface, and then insert tie bars. The tie bars 8@400 are spaced 400mm apart along the column height, and the tie bars of the upper and lower layers are staggered as much as possible.

[0038] Step S5: Installation and tensioning of external prestressing tendons 3. The external prestressing tendons 3 are arranged in a biomimetic fish-belly shape along the bottom of the beam. Specifically, this includes: a fixed base 51, a rotatable limiting member 52, high-strength bolts 53, and inverted V-shaped connectors 54. The fixed base 51 is fixed to the original transfer beam 4 by anchor bolts along both sides of its length, near the column end. Two inverted V-shaped connectors 54 are symmetrically fixed to the bottom of the fixed base 51 by high-strength bolts 53. The upper end of the rotatable limiting member 52 is movably positioned within the inverted V-shaped connector 54, and the external prestressing tendons 3 are inserted through the lower frame of the rotatable limiting member 52 to limit lateral displacement of the external prestressing tendons 3. When tensioning the prestress, the rotatable limiting member 52 can rotate along the prestress to adapt to the shape of the external prestressing tendons 3.

[0039] Step S51: According to the arrangement of the external prestressing tendons 3 and the steel strands, cut the materials. First, install the steel hanging rod 6. At a distance of 290mm from the beam end 41 and 280mm from the bottom of the slab, use a water drill to open a 60mm diameter through hole 401, so that it passes through the beam end 41 of the reinforced transfer beam 4. The hole should be as close as possible to the column end. Then, open a through groove 101 on the column side of the concrete to be demolished, close to the beam end 41, so that the external prestressing tendons 3 pass through the top of the concrete column close to the beam side.

[0040] Step S52: Install universal conversion support mechanism 5 on both sides of the concrete column 1 to be demolished. The universal conversion support mechanism 5 is fixed to the original concrete with anchor bolts. During installation, detect the position of the original steel bars in the beam. Step S53: After installing the steel hoist 6 and the universal conversion support mechanism 5, insert the external prestressing tendon 3. One end of the external prestressing tendon 3 is installed at the fixed end using a compression anchor. The other end is installed at the prestressing tensioning end using a wedge anchor. The external prestressing tendon 3 passes through the through hole 401 at a distance 41 from the beam end, passes through the wedge-shaped anchor plate, and then passes through the group anchor.

[0041] Specifically, the universal joint support mechanism 5 includes: a fixed base 51, an inverted U-shaped connector 5, Step S54: Pre-tension the external prestressing tendons.

[0042] Step S55: Tension the external prestressing tendons to the design required force value, including: symmetrically tensioning two bundles of external prestressing tendons in stages, using 50% of the standard value of the tensile ultimate strength of the prestressing tendons as the tension control stress, and performing tensioning in four stages: 0.3, 0.6, 0.9, and 1.0. The corresponding tension forces for each external prestressing tendon are 39.06 kN, 78.12 kN, 117.18 kN, and 130.2 kN, respectively. During each tensioning stage, all steel strands must complete one stage of tensioning before proceeding to the next. After the first tensioning is completed, the reinforcement for increasing the beam cross-section is tied, and extruded polystyrene boards are used to create cavity molds at the tensioning end. This allows for tension adjustments after the concrete beam is poured, during the removal of the concrete column, and afterwards. Tensioning is stopped once the intelligent steel strand monitoring values ​​meet the requirements, and then the cavity molds are sealed.

[0043] Step S6: Reinforce the transfer beam 4 using the cross-section enlargement method, changing the beam cross-section 42 from 250x650mm to 600x1000mm. This includes: treating the original component's interface surfaces, ensuring the surface unevenness of the transfer beam is no less than 6mm, chiseling grooves at regular intervals on the original component's casting surface to form shear keys, roughening the surface or creating grooves with a depth of no less than 6mm and a spacing no greater than the stirrup spacing or 200mm, and using a concrete interface binder when pouring new concrete. In this project, the increased cross-section portion is poured using self-compacting fine aggregate concrete. To ensure the compactness of the grouting, grouting should begin from one side and continue until overflow from the other side; simultaneous grouting from all sides is prohibited. Once grouting begins, it must be continuous without interruption, and the grouting time should be minimized. Vibration is strictly prohibited during grouting; if necessary, bamboo strips can be used for guiding the flow. When the thickness of the grouting layer exceeds a certain limit, grouting should be carried out in layers. However, the thickness of the bottom layer should not exceed 100m, and it should be carried out 8 to 10 hours after the first grouting.

[0044] Step S7: Demolish the concrete column 1 to be demolished in sections without support. This means that demolition can be carried out directly without the need for support. Specifically, this includes: Step S71: Erect protective frame 7. The erection range is 4m away from the concrete column to be demolished, and the height reaches the bottom of the slab. A U-shaped structure is formed on the outside of the two concrete columns to be demolished.

[0045] Step S72: Cut the connection between the concrete column 1 to be demolished and the structure, including: S721: Fix the track 81 of the wire saw power wheel 80 at a position 1m above the ground at the first concrete column 1 to be demolished; S722: Draw a horizontal line at the top of the concrete column to be demolished, 50mm from the bottom of the beam, as the horizontal line for cutting; S723: Install two steering pulleys 82 at the horizontal line 50mm above the top of the concrete column to be demolished, so that the wire saw can be steered; S724: Start the wire saw 83 to begin trial cutting; S725: During the cutting process, after the wire saw 83 has cut to a depth of about 100mm, stop cutting, turn off the power to the wire saw, insert a steel wedge into the cutting gap for the first time, and when the cutting depth reaches 200mm, stop cutting, turn off the power to the wire saw, and insert a steel wedge into the cutting gap for the second time; S726: After cutting is completed, turn off the power to the wire saw, let it stand for 1 hour, and then begin disassembling the equipment; S727: Repeat steps S721-S726 for the second concrete column to be demolished.

[0046] Step S73: Segmentally cut and break the two concrete columns to be demolished 1.

[0047] Furthermore, in step S73, the two concrete columns to be demolished are cut and broken in sections, including: Step S731: Insert chemical anchors 9 into the transfer beam, fix the chain hoist 10, and divide the concrete column to be demolished from top to bottom into sections of 200mm each, with the top section being the first section, and so on, until the bottom of the column. Step S732: Insert an anchor bolt in the middle of the first section, connect it to the chain hoist hook with a closing hook, and tension the chain hoist; Step S733: Before cutting begins, prepare wooden blocks. If there is an emergency during the cutting process, insert wooden blocks to hold them in place. Step S734: Start cutting the first section. The first step has already used a wire saw to cut the top of the column from the structure. After the cutting is completed, use a water drill to disconnect the first section from the lower column. Step S735: After cutting, use a chain hoist to slowly and steadily place the first section on the ground; Step S736: Cut the second section. First, insert an anchor bolt in the middle of the second section, connect it with the chain hoist hook using a closed hook, and tension the chain hoist. After cutting, use the chain hoist to slowly and steadily place the second section on the ground, and dismantle it in sequence. Step S737: Crush the dismantled column segments and remove them, completing the cutting and crushing of the first concrete column to be demolished. Step S738: Cut and break another concrete column to be demolished in the same order. Step S8: During the demolition of the concrete column, monitor in real time the mid-span displacement of the transfer beam, the stress change of the transfer beam, and the changes of the external prestressing tendons before, during, and after the column demolition, including: Step S81: Arrange stress monitoring points: Set up three stress monitoring points at intervals at the bottom mid-span of the transfer beam, such as by setting up strain gauges at the bottom of the beam to monitor the stress changes of the beam; Step S82: Arrange displacement monitoring points: Set three deflection monitoring points at intervals at the mid-span of the transfer beam, and set two horizontal displacement monitoring points at the top of the two concrete columns adjacent to the concrete column to be demolished, such as by setting displacement gauges to monitor the mid-span displacement of the beam. Step S83: Use smart steel strands to monitor the changes in prestressed tendons during column removal. Two smart steel strands, each with three measuring points, are used for real-time monitoring during the column removal process.

[0048] (1) The manufacturing process of intelligent steel strand is as follows: The intelligent steel strand is manufactured using an intelligent optical fiber groove embedding process. A groove about 0.5mm deep is made on the surface of the steel wire (the center wire of the steel strand), and an intelligent optical fiber with a diameter of 0.1mm is embedded and coupled together with the steel wire and the steel strand to form the intelligent steel strand.

[0049] (2) Static load limit performance index and sensing performance index of intelligent steel strand: The fabricated intelligent steel strand was placed in a tensioning table and connected to a fiber optic grating demodulator for tensioning. To better calibrate the intelligent steel strand, at least 10 tensioning stages were performed. The fracture test calibration data are shown in Table 1. The static load tension calibration test results show that the grating sensor can track the steel strand breakage and that the strand is subjected to coordinated stress. The ultimate load of the intelligent steel strand is 260.3 kN, meeting the mechanical performance requirements of ordinary steel strands. The measured strain sensitivity coefficient of the intelligent steel strand is... The linearity of the calibration curve can reach over 99%, and the repeatability error does not exceed 0.5%.

[0050] (3) Fatigue performance indicators: Simultaneously using 3 intelligent steel strands , The stress amplitude was subjected to 2 million fatigue tests. The test results showed that the intelligent steel strand has good fatigue performance and can meet the requirements for long-term monitoring.

[0051] Table 1. Fracture Test Calibration Data The intelligent monitoring results of this invention can be fed back to the terminal control system in real time. The terminal control system automatically controls the hydraulic oil pump to control the tension value and make real-time adjustments, thereby realizing dynamic feedback and construction adjustments. The intelligent monitoring feedback process is as follows: (1) Setting the safety threshold for monitoring data: Based on structural design specifications and PKPM calculation results, pre-set warning thresholds and limit thresholds for each monitoring parameter: Mid-span displacement of transfer beam: The warning threshold is 80% of the calculated allowable deflection (e.g., L / 400, where L is the beam span), and the ultimate threshold is 95% of the allowable deflection; Stress variation in transfer beams: The warning threshold is 70% of the design strength standard value, and the ultimate threshold is 85% (to avoid overstress failure); Changes in prestressed steel strands: The warning threshold is 10% of the initial tension loss (e.g., if the initial tension is 130.2 kN and the loss is ≥13 kN, an early warning is issued), and the extreme threshold is ≥20% of the loss (immediate intervention is required).

[0052] (2) Establish a dynamic feedback and construction adjustment mechanism: By collecting sensor data in real time (fiber optic signals from intelligent steel strands, strain points at the bottom of the beam, and displacement gauge data), and comparing it with a threshold, a graded response is triggered. Normal state (below the warning value): Continue dismantling according to the original plan, maintain the current dismantling speed (e.g., 200mm per section), and record the data trend.

[0053] Warning status: Suspend dismantling and analyze the cause of abnormal data: If the displacement / stress is growing too fast: extend the dismantling time of the current segment (e.g., from 2 hours / segment to 4 hours) and reduce the amount of dismantling at one time; if the prestress loss is abnormal: check whether the intelligent steel strand is damaged, and if necessary, re-tension or replace the steel strand.

[0054] Extreme condition: Stop dismantling immediately and take emergency measures: If the prestress loss exceeds the limit: re-tension the external prestressing tendons to the design value, or increase the number of intelligent steel strands to supplement monitoring.

[0055] (3) Adjustment of forecasts based on data trends: By analyzing trends in historical and current data, the structural response in the subsequent demolition phase can be predicted, and the plan can be optimized in advance: if the slope of the displacement-demolition progress curve suddenly increases (e.g., the displacement rate is 0.5 mm / segment in the first 3 segments and increases to 1.2 mm / segment in the 4th segment), it is predicted that the subsequent deformation may exceed the limit, and the demolition speed should be reduced or the segment length should be increased (e.g., from 200 mm / segment to 150 mm / segment).

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for intelligently monitoring and dismantling columns of unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beams, characterized in that: Includes the following steps: S1. Determine the concrete columns to be demolished and related structures based on the structural drawings; S2. Use PKPM software to perform overall structural modeling, calculation and analysis, and determine the reinforcement method of external prestressing combined with increasing the cross section based on the calculation and analysis results; S3. Construction preparation: Lay out and position the external prestressing tendons according to the design drawings; S4. Reinforce other concrete columns that are not to be demolished and are on the same axis as the concrete column to be demolished; S5. Installation and tensioning of external prestressing tendons, wherein the external prestressing tendons are arranged in a biomimetic fish belly shape along the bottom of the beam; S6. The transfer beam is reinforced by increasing the cross-section. S7. Segmented demolition of concrete columns to be demolished under unsupported conditions. S8. During the demolition of the concrete column to be demolished, monitor in real time the mid-span displacement of the transfer beam, the stress change of the transfer beam, and the changes of the external prestressing tendons during the column demolition.

2. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 1, characterized in that: In step S2, the overall structure is modeled, calculated, and analyzed using PKPM software, including: S211. Establish an unreinforced structural model according to the original structural drawings. According to the requirements of the new function, apply new loads to the structure and calculate and analyze to obtain the reinforcement area required for the unreinforced structure to meet the bearing capacity and service requirements. At the same time, determine whether the original cross section of the structure meets the bearing capacity requirements. If it does not meet the requirements, the cross section needs to be increased for reinforcement. S212. Based on the calculation results of the unreinforced structural model, establish the first reinforced structural model. In the first reinforced structural model, increase the original beam cross-section to a transfer beam cross-section and increase the original column cross-section. Perform calculation and analysis on the first reinforced structural model to determine whether the added cross-section meets the bearing capacity requirements. S213. Based on the first reinforced structural model, nodal forces are added to simulate the effect of external prestressing tendons on the structure. At the same time, one concrete column in the middle is removed to form a second reinforced structural model. After removing one column, the span of the transfer beam changes from the original 4m span to 8m span. The second reinforced structural model is calculated and analyzed to determine whether the bearing capacity and deflection of the transfer beam meet the requirements after applying prestress and removing one concrete column. S214. Based on the second reinforced structure model, remove another concrete column and change the span of the transfer beam from 8m to 12m to form the third reinforced structure model. Perform calculation and analysis on the third reinforced structure model to check whether the bearing capacity of the beam and column meets the requirements and whether the deflection of the transfer beam meets the requirements. S215. Use the masonry reinforcement module for calculation and analysis. The calculation and analysis process shall be carried out in accordance with the requirements of steps S211 to S214. S216. Compare the calculation results of the concrete structure module and the masonry reinforcement module in PKPM, and take the maximum value of the two reinforcement calculation results for reinforcement treatment.

3. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 1, characterized in that: In step S2, the reinforcement method of external prestressing combined with increasing the cross-section is determined, including: S221. For the four adjacent concrete columns on the same axis as the two concrete columns to be demolished in the middle, the cross-section should be increased for reinforcement. S222. External prestressing tendons are used for reinforcement. The external prestressing tendons are in two bundles, which are placed on the bottom surface of the original beam. The distance between the two bundles of external prestressing tendons is less than or equal to the width of the original beam. Each bundle of external prestressing tendons includes three unbonded steel strands, one of which is a smart steel strand. The smart steel strand has an optical fiber in its center, which can read the stress change of the external prestressing tendon. The optical signal is converted into an electrical signal to further read the prestress strain. The prestressing tensioning end is set at the two concrete columns adjacent to the concrete column to be demolished, on the outside of the beam end perpendicular to the transfer beam. The beam end is drilled with a water drill to allow the external prestressing tendon to pass through and is anchored on one side of the beam end. S223. The transfer beam is reinforced by increasing the cross-section.

4. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 3, characterized in that: In step S5, the installation and tensioning of the external prestressing tendons, wherein the external prestressing tendons are arranged in a biomimetic fish-belly shape along the bottom of the beam, includes: S51. According to the arrangement of the external prestressing tendons and the steel strands, cut the materials first, install the steel hanging rods, and drill 80mm diameter holes with a water drill at 290mm from the end of the beam and 280mm from the bottom of the slab to reinforce the transfer beam. S52. Install the universal joint conversion support mechanism, and detect the position of the original steel bars in the beam during installation; S53, Inserted external prestressing tendons; S54. Pre-tension the external prestressing tendons; S55. Tension the external prestressing tendons to the design required force value.

5. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 4, characterized in that: In step S55, the external prestressing tendons are tensioned to the design required force value, including: symmetrically tensioning two bundles of external prestressing tendons in stages, with the tension control stress taken as 50% of the standard value of the tensile ultimate strength of the prestressing tendons, and tensioning is carried out in four stages: 0.3, 0.6, 0.9, and 1.

0. The corresponding tension forces for each external prestressing tendon are 39.06kN, 78.12kN, 117.18kN, and 130.2kN, respectively. During each stage of tensioning, all steel strands must complete one stage of tensioning before proceeding to the next stage.

6. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 3, characterized in that: In step S6, the transfer beam is reinforced by increasing the cross-section, including: treating the joint surface of the original component, wherein the unevenness of the transfer beam surface is not less than 6mm, and grooves are chiseled at certain intervals on the casting surface of the original component to form shear keys, and the surface is roughened or grooved, with a groove depth of not less than 6mm and a spacing not greater than the stirrup spacing or 200mm, and a concrete interface binder is used when pouring new concrete.

7. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 6, characterized in that: In step S7, the concrete column to be demolished is dismantled in sections under unsupported conditions, including: S71. Erect a protective frame. The frame shall be erected within a 4m radius of the concrete columns to be demolished, extending to the bottom of the slab, and forming a U-shaped structure on the outside of the two concrete columns to be demolished. S72. Cut the connection between the concrete column to be demolished and the structure, including: S721. Fix the track of the wire saw's power wheel at a position 1m above the ground at the first concrete column to be demolished; S722. Draw a horizontal line at the top of the concrete column to be demolished, 50mm from the bottom of the beam, as the horizontal line for cutting; S723. Install two steering pulleys at the horizontal line 50mm above the top of the concrete column to be demolished, so that the wire saw can be steered; S724. Start the wire saw to begin trial cutting; S725. During the cutting process, after the wire saw has cut to a depth of about 100mm, stop cutting, turn off the power to the wire saw, and insert a steel wedge into the cutting gap for the first time. When the cutting depth reaches 200mm, stop cutting, turn off the power to the wire saw, and insert a steel wedge into the cutting gap for the second time; S726. After cutting is completed, turn off the power to the wire saw, let it stand for 1 hour, and then begin disassembling the equipment; S727. Repeat steps S721-S726 for the second concrete column to be demolished. S73. Cut and break the two concrete columns to be demolished in sections.

8. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 7, characterized in that: In step S73, the two concrete columns to be demolished are cut and broken in sections, including: S731. Insert chemical anchors into the transfer beam, fix the chain hoist, and divide the concrete column to be demolished from top to bottom into sections of 200mm each, with the top section being the first section, and so on, until the bottom of the column. S732. An anchor bolt is inserted in the middle of the first section and connected to the chain hoist hook with a closing hook to tension the chain hoist. S733. Before cutting begins, prepare wooden blocks. If there is an emergency during the cutting process, insert wooden blocks to hold them in place. S734. Start cutting the first section. The first step has already used a wire saw to cut the top of the column from the structure. After the cutting is completed, use a water drill to disconnect the first section from the lower column. S735. After cutting, use a chain hoist to slowly and steadily place the first section on the ground; S736. Cut the second section. First, insert an anchor bolt in the middle of the second section. Connect the closing hook to the chain hoist hook. Tension the chain hoist. After cutting, use the chain hoist to slowly and steadily place the second section on the ground. Remove it in sequence. S737. Break up the dismantled column segments and remove them, completing the cutting and breaking of the first concrete column to be demolished. S738. Cut and break another concrete column to be demolished in the same order.

9. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 8, characterized in that: In step S8, during the demolition of the concrete column to be demolished, the mid-span displacement of the transfer beam, the stress change of the transfer beam, and the changes of the prestressed steel strands during the column demolition are monitored in real time, including: S81. Three stress monitoring points are set at intervals at the bottom mid-span of the transfer beam to monitor the stress changes of the beam. S82. Three deflection monitoring points are set at intervals at the mid-span of the transfer beam, and two horizontal displacement monitoring points are set at the top of the two concrete columns adjacent to the concrete column to be demolished to monitor the mid-span displacement of the beam. S83. Use intelligent steel strands to monitor the changes of prestressed tendons during column dismantling.

10. The method for dismantling columns of an unsupported prestressed tendon spatial biomimetic fish-belly-shaped reinforced transfer beam according to claim 4, characterized in that: The universal conversion support mechanism is fixed to both sides of the concrete column to be demolished with anchor bolts. Steel hanging rods are installed on the inner side of the two concrete columns adjacent to the concrete column to be demolished. The steel hanging rods are 290mm from the inner side of the beam end and 280mm from the bottom of the slab, and pass through the conversion beam. One end of the external prestressing tendon is installed at the fixed end with an extrusion anchor, and the other end is installed at the tensioning end with a wedge anchor. When tensioning the external prestressing tendon, the external prestressing tendon adapts to the angle through the universal conversion support mechanism and transmits the lifting force to the conversion beam.

Images