Construction method of post-added steel beam of existing frame structure

Abstract

The invention relates to the technical field of engineering structure transformation and reinforcement, and discloses a construction method for a post-added steel beam of an existing frame structure, which comprises the following steps: S1, positioning and paying off: popping up position lines of a support anchor plate and a U-shaped hoop according to requirements; s2, existing frame beams and existing floor base layers are treated; s3, a steel plate U-shaped hoop is pasted on the existing frame beam and pressurized and fixed, and the steel plate U-shaped hoop is close to the support anchor plate; s4, a support anchor plate is manufactured and installed; s5, post-reinforcement steel beam ground manufacturing and lifting installation are carried out; and S6, joint sealing and glue injection are conducted on the support anchor plate, specifically, the periphery of the support anchor plate is sealed through joint sealing glue, and sticky steel pouring glue is poured into a gap between the support anchor plate and existing frame beam concrete. By changing the traditional process sequence, the problems of defects and hidden dangers caused by gas cutting trepanning, oblong hole reserving and direct welding of a connecting plate and a section steel beam in existing actual construction, trivial and complicated hoisting work amount, insufficient floor bearing capacity and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering structure renovation and strengthening, and particularly relates to a construction method for adding a steel beam to an existing frame structure. Background Art

[0002] In an existing frame structure, reducing the floor slab span by adding supports (such as adding new beams, columns or steel supports) is an effective method to improve the floor bearing capacity. This method can significantly reduce the floor slab bending moment and deformation, and enhance the overall bearing capacity. In actual operation, the method of adding a post-installed steel beam to improve the floor bearing capacity is extremely common, which has transparent price, short construction period, environmental protection, strong durability and safety.

[0003] Its general technological process is: positioning and setting out → base treatment → drilling and implanting bolts → installing the support anchor plate → welding the connecting plate and the support anchor plate → fabricating and installing the steel beam → caulking between the steel beam and the bottom of the original floor slab → painting. However, there are many drawbacks and potential hazards in the existing actual construction: 1. After the support anchor plate is drilled according to the design dimensions, holes are drilled in the existing main beam according to the hole size of the anchor plate to implant anchor bolts. At this time, it is impossible to use an electric hammer to drill holes, and the original beam stirrups and stress bars will surely be encountered. Only a water drill can be used to drill holes, and the original beam steel bars will surely be cut off by the water drill. There is no additional encrypted stirrup set at the mid-span of the original beam. Now, adding a post-installed steel beam increases a concentrated load, and combined with the situation of cutting off the original beam stirrups by the water drill, unfavorable factors are stacked up layer by layer.

[0004] 2. The holes of the support anchor plate, the holes of the connecting plate, and the bolt connection holes at the end web of the steel beam are cut and opened on-site by gas cutting. Because the gas cutting and hole expanding are highly random and the cutting surface is rough, it is clearly prohibited by the specification.

[0005] 3. When adding a post-installed steel beam to an existing structure, due to factors such as fixed construction space and construction errors of original components, oblong holes are generally opened on the connecting plate or the end of the steel beam to facilitate the smooth penetration of high-strength bolts. The specific drawbacks are as follows: 1). Damaging the structural strength and integrity The overall strength of the steel structure depends on the continuity of the steel. If the size, position or arrangement of the oblong hole is improper, it will directly reduce the effective bearing area of the cross-section. Especially under dynamic loads (such as live load, wind load, seismic force), stress concentration is likely to occur at the edge of the oblong hole, resulting in local cracking or fatigue failure.

[0006] 2). Affecting the impact resistance If the long axis direction of the oblong hole is consistent with the stress direction, the shear and bending resistance of the structure will be significantly reduced. For example, under the action of horizontal load, the oblong hole may exacerbate the deformation of the beam or column, weakening the ability of the structure to resist deformation.

[0007] 3). Increasing the deformation risk Long round holes may lead to uneven distribution of steel structure stiffness. If the holes are densely packed or located in key stress-bearing areas (such as near nodes), it will cause local buckling or overall instability, increasing the risk of building collapse.

[0008] 4 In actual construction, oblong holes are opened or the holes are too large. In order to reduce the deformation of the steel beam, the connection plate and the steel beam are directly welded. In general, pressure-bearing bolts are suitable for steel structure connections that bear static loads in industrial and civil buildings. Pressure-bearing connections allow joints to slip and have large deformations, while the deformation of welds is limited. Therefore, from a design concept, pressure-bearing connections cannot be used together with welding. This is a mandatory clause in the specification.

[0009] 5 After the connection plate and the support anchor plate are welded, lift or support the steel beam to the connection plate position, make the web plate of the steel beam close to the connection plate, and temporarily fix it, and then use the electromagnetic drill to open the hole. This method can meet the requirements of the specification, but there are also some disadvantages: 1) It is a high-altitude operation, not only anti-falling measures are required, but also the construction time is low; 2) The electromagnetic drill is for side construction, and a special person needs to be assigned to spray the cutting fluid from the side, and the working space is crowded and narrow. 3) Before construction, there must be measures to prevent the machine from falling due to unexpected power outages, and during construction, attention must be paid to the vibration of the machine moving downward and timely adjustments must be made.

[0010] 6. For the installation of steel beams after adding steel beams to the existing structure, the following methods are generally used: the holes in the floor slab are opened and lifted with a steel chain hoist or lifted with a forklift. Both construction methods have certain disadvantages: the holes in the floor slab must be filled in, and if the decorative surface layer is involved, a lot of trivial work will be added; the forklift lifting can only be carried out when the original floor slab bearing capacity meets the forklift load (forklift self-weight + lift weight + forklift braking force, etc.). If the floor slab bearing capacity is far from meeting the forklift operating conditions, the operation cannot be carried out.

[0011] 7. The conventional steel beams are caulked with the bottom of the original floor slabs, and the newly added components are not subjected to stress in time, so the bearing capacity of the steel beams cannot be fully utilized. Summary of the invention

[0012] The purpose of the present invention is to provide a construction method for adding steel beams to an existing frame structure to solve the problems in the background technology.

[0013] The above technical objectives of the present invention are achieved through the following technical solutions: A construction method for adding steel beams to an existing frame structure comprises the following steps: S1: Positioning and laying out: Pop out the support anchor plate and U-shaped hoop position lines as required, including horizontal lines, vertical lines, center lines, etc., to facilitate the positioning of the steel beam.

[0014] S2: Treatment of existing frame beams and existing floor slabs: Remove the dust, floating slurry, dirt, oil stains, original coatings, plaster layers or other finishing layers on the surfaces of the corresponding positions of the existing frame beams and existing floor slabs. Defects such as weathering, peeling, looseness, sanding, honeycombing, pitting, and corrosion on the concrete surface should be removed. After leveling with structural adhesive, use a angle grinder to chisel or polish the concrete bonding surface until the hard layer is exposed.

[0015] S3: Paste and press-fix steel plate U-shaped hoops on the existing frame beams, with the steel plate U-shaped hoops close to the support anchor plates; after folding the thin steel plate into a U-shaped hoop according to the cross-sectional dimensions of the existing frame beams, the mixed steel-bonding adhesive should be applied to both the steel plate U-shaped hoops and the concrete bonding surfaces at the same time. After checking that there is no missed application, the steel plate U-shaped hoops can be pasted to the concrete of the existing frame beams; the average thickness of the adhesive layer after pasting should be controlled within 2 mm to 3 mm. By adding steel plate U-shaped hoops, the problem of excessive concentrated force of the later-added steel beams is solved, and the concentrated bearing capacity of the existing frame beams is dispersed and shared.

[0016] S4: Fabrication and installation of support anchor plates: S5: Fabrication of the later-added steel beams on the ground and hoisting and installation: S6: Sealing and injecting glue for support anchor plates: Bond the injection nozzles to the injection holes at the bottom of the support anchor plates (2 symmetrically), insert exhaust pipes at the corner points and edges of the support anchor plates, with the exhaust hole spacing of 30 - 40 cm, and then seal the periphery of the support anchor plates with sealant. After the edge sealant cures, use a pump to pour the steel-bonding injection glue from the injection nozzles into the gap between the support anchor plates and the concrete of the existing frame beams. The pouring work continues until glue flows out of all the exhaust pipes. During the pouring process, use a rubber hammer to tap the support anchor plates to confirm whether the pouring is dense. Sealing and injecting glue can make the shear resistance of the screw synchronous and enhance the bonding force between the support anchor plates and the original concrete.

[0017] S8: Painting. After the installation of the steel beams is completed, for the pre-reserved connecting plates, support anchor plates and other parts, use the same process as the steel beams for painting: conduct rust removal treatment on the surface, and the rust removal grade should meet the design requirements. Then, apply anti-corrosion and fire-proof coatings, and the variety, number of layers, thickness, etc. of the coatings should meet the design requirements. The anti-corrosion and fire-proof coatings should be applied evenly, without missed application or running.

[0018] The present invention is further set as: The S4: Fabrication and installation of support anchor plates includes: S4-1: Treatment of the concrete surface of the existing frame beams; According to the requirements of the design drawings and combined with on-site measurement and positioning, mark the layout of the support anchor plates on the concrete surface of the existing frame beams and conduct grinding treatment to expose the solid concrete and form a flat rough surface. Use a pointed chisel to gently level the uneven parts, then brush with a wire brush, remove the surface loose materials, and finally rinse thoroughly with high-pressure water. After being completely dried, wipe the surface with absorbent cotton dipped in acetone or blow dry with oil-free high-pressure air.

[0019] S4-2: Drilling and embedding bolts; Use a reinforced concrete cover meter to identify the arrangement of the steel bars in the existing frame beam to avoid hitting the steel bars during drilling. Mark the positions where drilling is required according to the requirements of the design drawings. The hole diameter and depth should be strictly constructed according to the design requirements. After the hole is drilled, embed the bolts.

[0020] S4-3: Making the formwork and the bearing anchor plate; Cut the anchor plate according to the actual layout on the on-site concrete. Use 10-mm-thick extruded polystyrene board to make a formwork for the bolts embedded on-site, and drill holes for the newly added bearing anchor plate to be installed.

[0021] S4-4: Installing the bearing anchor plate; First, apply steel-bonding glue around the bolts, then fix the bearing anchor plate on the bolts, and ensure the gap between the bearing anchor plate and the concrete surface to ensure the thickness of the perfusion glue layer.

[0022] By first embedding the bolts and then making the formwork and drilling holes to make the bearing anchor plate, the steel bar structure of the existing frame beam can be prevented from being damaged when the bolts are embedded.

[0023] The present invention is further configured as follows: The said S5: Fabrication and hoisting installation of the later-added steel beam on the ground include: S5-1: Cutting the section steel beam: According to the design dimensions and shape of the section steel beam and combining with the on-site actual situation, use gas cutting or a plasma cutting machine to cut on-site to ensure accurate cutting dimensions. After cutting, grind the edges of the section steel beam to remove burrs and iron oxide.

[0024] S5-2: Assembling and drilling holes: Place the cut section steel beam flat on the ground with the web facing up. According to the design requirements and the on-site measured dimensions, temporarily fix the pre-prepared connecting plate to the end web of the section steel beam with spot welding, and use an electromagnetic drill to drill holes. After the hole opening is completed, knock off the connecting plate temporarily fixed on the web of the section steel beam (to leave an operating space for hoisting the section steel beam and facilitate construction). Then grind off the weld spots.

[0025] S5-3: Installing the section steel beam; After the section steel beam is processed, use a special section steel hoisting machine to hoist it in place (the self-weight of the hoisting machine is 200 kg, the effective hoisting height is 8 m, and the maximum hoisting weight is 400 kg). Fix the connecting plate (the connecting plate after on-site hole drilling) to the end web of the section steel beam with high-strength bolts. After adjusting the position of the section steel beam, weld the connecting plate and the bearing anchor plate using carbon dioxide gas shielded welding. After the weld cools down, tighten the high-strength bolts.

[0026] By using a special section steel hoisting machine, not only the trivial engineering quantity increased by the floor opening and the cooperation of the steel chain hoist for hoisting is avoided, but also the problem that when the floor bearing capacity far cannot meet the forklift operation conditions, the operation cannot be carried out is solved.

[0027] The present invention is further configured as follows: It further includes S7: preloading the profiled steel beam and inserting support steel plates; after the connection plate is welded to the support anchor plate and the curing time of the steel-bonding grouting adhesive in the support anchor plate is satisfied, the existing floor slab is preloaded through a pair of jacks at the mid-span of the profiled steel beam, and support iron plates are inserted between the profiled steel beam and the bottom of the original floor slab, and then high-strength polymer mortar is used to fill the joints throughout the length.

[0028] By preloading the profiled steel beam and inserting support iron plates, the problem that the post-added profiled steel beam and the floor slab cannot be stressed in a timely and coordinated manner and the bearing capacity cannot be fully exerted is solved.

[0029] The present invention is further configured as follows: The curing time of the steel-bonding grouting adhesive is not less than 3 days to ensure the effective curing time of the steel-bonding grouting adhesive and the bonding strength of the support anchor plate.

[0030] The present invention is further configured as follows: After the S4-3 sleeve mold and the support anchor plate are made and drilled, the bonding surface of the support anchor plate is rust-removed and roughened with a grinding machine or a wire brush grinder; the grinding lines should be perpendicular to the stress direction of the support anchor plate; the surface of the support anchor plate is wiped clean with absorbent cotton dipped in acetone.

[0031] The present invention is further configured as follows: In S4-4: when installing the support anchor plate, the gap between the support anchor plate and the concrete surface > 3mm to ensure the thickness of the glue layer and also offset the accumulated error generated during the installation of the profiled steel beam.

[0032] The present invention is further configured as follows: The special profiled steel lifting machine is an air duct automatic lifting machine disclosed in CN218231723U. Such a lifting machine is light in weight and can adapt to the bearing capacity of the floor slab.

[0033] The prominent effect of the present invention is: Compared with the prior art, by changing the traditional process sequence: drilling and implanting screw rods → installing the support anchor plate → welding the connection plate to the support anchor plate → fabricating and installing the steel beam. It is changed to: drilling and implanting screw rods → installing the support anchor plate → pre-assembling the profiled steel beam and the connection plate on the ground and then taking holes → lifting the profiled steel beam and welding the connection plate; not only solves the drawbacks and hidden dangers existing in gas cutting and opening holes, leaving oblong holes, and directly welding the connection plate to the profiled steel beam during actual construction, but also can reduce the high-altitude operation time and increase work efficiency.

[0034] By implanting screw rods first and then taking holes with the sleeve mold and sealing the joints and injecting glue, the shear resistance of the screw rods can be synchronized, and the bonding force between the support anchor plate and the original concrete can be enhanced.

[0035] By adding steel plate U-shaped hoops, the problem of excessive concentrated force of the post-added profiled steel beam is solved.

[0036] By using a special steel beam lifting machine, not only the trivial engineering work increased by floor slab hole opening and cooperation with chain hoists for lifting is avoided, but also the problem that operation cannot be carried out when the floor bearing capacity far cannot meet the forklift operation conditions is solved.

[0037] By preloading the steel beam, the steel beam is stressed in time, and the problem that the bearing capacity of the post-added steel beam cannot be fully exerted is solved. Brief Description of the Drawings

[0038] Figure 1 It is a schematic diagram of a post-added steel beam structure for an existing frame structure; Figure 2 It is a schematic diagram of the reinforcement node between the steel beam and the existing floor slab; Figure 3 It is a schematic diagram of the loading node of the steel beam; Figure 4 It is a flowchart of the method of the present invention; Figure 5 It is a flowchart of the fabrication and installation part of the support anchor plate; Figure 6 It is a flowchart of the fabrication on the ground and the lifting and installation part of the post-added steel beam.

[0039] Reference Signs in the Drawings: 1. Existing frame beam; 2. Existing floor slab; 3. Steel beam; 4. High-strength bolt; 5. Connecting plate; 6. Support anchor plate; 7. Embedded anchor bolt; 8. Support iron plate; 9. High-strength polymer mortar. Detailed Embodiment

[0040] The following will further describe in detail the specific embodiments of the present invention in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0041] The following reference Figures 1 to 6 is used to illustrate the present invention: A post-added steel beam structure for an existing frame structure, as Figure 1 shown, includes an existing frame beam 1 and an existing floor slab 2. A steel beam 3 is provided between two adjacent existing frame beams 1, and the steel beam 3 is located below the existing floor slab 2; the end of the steel beam 3 is fixed to a connecting plate 5 through a high-strength bolt 4, the connecting plate 5 is welded to a support anchor plate 6, the support anchor plate 6 is fixed to an embedded anchor bolt 7, and the embedded anchor bolt 7 is connected to the existing frame beam 1; at least one steel plate U-shaped hoop is provided on each side of each support anchor plate 6, the steel plate U-shaped hoop is inserted on the existing frame beam 1, and the steel plate U-shaped hoop is connected to the existing frame beam through bonding adhesive and anchor bolts.

[0042] As Figure 2As shown in the figure, there is a steel-bonding grouting adhesive layer between the support anchor plate 6 and the existing frame beam. A support iron plate 8 is inserted between the upper part of the profiled steel beam 3 and the bottom surface of the existing floor slab 2. The distance between adjacent support iron plates is 500 mm. The thickness of the support iron plate 8 is adjusted according to the gap between the existing floor slab and the profiled steel beam after loading. The remaining gaps between the profiled steel beam and the existing floor slab are filled with high-strength polymer mortar 9.

[0043] A construction method for adding a profiled steel beam to an existing frame structure includes the following steps: S1: Positioning and layout: Pop the position lines of the support anchor plate and U-shaped hoops according to requirements, including horizontal lines, vertical lines, center lines, etc., for the positioning of the profiled steel beam.

[0044] S2: Treatment of the base layer of the existing frame beam and the existing floor slab; Remove the dust, floating slurry, dirt, oil stains, original coatings, plaster layers or other finishing layers on the corresponding surfaces of the existing frame beam and the existing floor slab. Defects such as weathering, peeling, looseness, sanding, honeycombing, pitting, and corrosion on the concrete surface should be removed. After leveling with structural adhesive, the concrete bonding surface should be chiseled or polished with a angle grinder until the hard layer is exposed.

[0045] S3: Paste and press-fix the steel plate U-shaped hoops on the existing frame beam. The steel plate U-shaped hoops are close to the support anchor plate; After folding the thin steel plate into a U-shaped hoop according to the cross-sectional dimensions of the reinforced beam (i.e., the existing frame beam), the mixed steel-bonding adhesive should be applied to both the steel plate U-shaped hoop and the concrete bonding surface at the same time. After checking that there is no missed application, the steel plate U-shaped hoop can be pasted to the concrete of the existing frame beam; The average thickness of the adhesive layer after pasting should be controlled within 2 mm to 3 mm. When pasting vertically, the adhesive layer should be thicker at the top and thinner at the bottom; When pasting upside down, the vertical flow of the adhesive liquid should not be greater than 3 mm. The surface should be flat when pasting the steel plate U-shaped hoop, and the transition of the step difference should be smooth without sharp corners. After pasting the steel plate U-shaped hoop, it should be fixed by uniformly distributing points and pressing. The pressing sequence should be from one end of the steel plate U-shaped hoop to the other end point by point, or from the middle of the steel plate U-shaped hoop to both ends point by point; It is not allowed to press from both ends of the steel plate U-shaped hoop to the middle. The pressing and fixing is the anchor bolt (or screw) pressing method.

[0046] S4: Fabrication and installation of the support anchor plate: S4-1: Treatment of the concrete surface of the existing frame beam; According to the requirements of the design drawings and combined with on-site measurement and positioning, the large pattern of the support anchor plate position is marked on the concrete surface of the existing frame beam, and grinding treatment is carried out to expose the solid concrete and form a flat rough surface. The uneven surface should be gently chiseled and leveled with a pointed chisel, then brushed with a wire brush to remove the surface loose material, and finally rinsed thoroughly with high-pressure water. After being completely dry, wipe the surface with absorbent cotton dipped in acetone or blow dry with oil-free high-pressure air.

[0047] S4-2: Drilling and embedding bolts; Use a reinforced concrete cover meter to identify the arrangement of steel bars in the existing frame beam concrete to avoid hitting the steel bars during drilling. Mark the positions where drilling is required according to the requirements of the design drawings. The hole diameter and depth should be strictly constructed according to the design requirements. After the hole is drilled, embed the bolts.

[0048] S4-3: Making the formwork and the support anchor plate; Cut the anchor plate according to the actual layout on the site concrete. Use 10-mm-thick extruded polystyrene board to make a formwork for the bolts embedded on the site. Drill holes for the new support anchor plate to be installed. Then, use a grinding wheel or a wire brush grinder to remove rust and roughen the bonding surface of the support anchor plate. The grinding lines should be perpendicular to the stress direction of the support anchor plate; Wipe the surface of the support anchor plate clean with absorbent cotton dipped in acetone.

[0049] S4-4: Installing the support anchor plate; First, apply steel-bonding glue around the bolts, and then fix the support anchor plate on the bolts, ensuring that the gap between the support anchor plate and the concrete surface is more than 3 mm to ensure the thickness of the grouting layer.

[0050] S5: Fabrication and hoisting installation of the post-added steel beam on the ground: S5-1: Cutting the section steel beam: According to the design dimensions and shape of the section steel beam and the actual situation on the site, use gas cutting or a plasma cutting machine to cut the section steel beam on the site to ensure accurate cutting dimensions. After cutting, grind the edges of the section steel beam to remove burrs and iron oxide.

[0051] S5-2: Assembling and drilling holes: Place the cut section steel beam flat on the ground with the web facing up. According to the design requirements and the actual measured dimensions on the site, temporarily fix the pre-prepared connecting plate to the end web of the section steel beam with spot welding, and use an electromagnetic drill to drill holes. After the hole opening is completed, knock off the connecting plate temporarily fixed on the web of the section steel beam (to leave an operating space for hoisting the section steel beam and facilitate construction). Then, grind off the weld spots.

[0052] S5-3: Installing the section steel beam; After the section steel beam is processed, use a special section steel hoisting machine to hoist it in place (the special section steel hoisting machine is a kind of air duct automatic lifting hoist disclosed in CN218231723U, with a self-weight of 200 kg, an effective hoisting height of 8 m, and a maximum hoisting weight of 400 kg). Fix the connecting plate (the connecting plate after drilling holes on the site) to the end web of the section steel beam with high-strength bolts. After adjusting the position of the section steel beam, weld the connecting plate and the support anchor plate using carbon dioxide gas shielded welding. After the weld cools down, tighten the high-strength bolts. The self-weight of the existing ordinary hydraulic forklift is nearly 2 tons, and the load-bearing capacity of the floor is about 600-1000 kg per square meter. The self-weight of the hydraulic forklift plus the section steel beam exceeds the load-bearing capacity of the floor, resulting in a greater risk.

[0053] S6: Sealing and injecting glue into the bearing anchor plate: Bond the injection nozzles to the injection holes at the bottom of the bearing anchor plate (2 nozzles symmetrically). Insert exhaust pipes at the corner points and the edges of the bearing anchor plate, with the exhaust holes spaced 30 - 40 cm apart. Then, seal the periphery of the bearing anchor plate with sealing glue. After the edge-sealing glue cures, use a pump to inject the steel-bonding perfusion glue from the injection nozzles into the gap between the bearing anchor plate and the existing frame beam concrete until glue flows out of all the exhaust pipes. During the perfusion process, tap the bearing anchor plate with a rubber hammer to confirm whether it is densely perfused.

[0054] S7: Preloading the steel beam and inserting support steel plates; After the connection plates of the steel beam are welded to the bearing anchor plate and the perfusion glue in the bearing anchor plate has cured for 3 days, preload the existing floor slab at the mid-span of the steel beam through a pair of jacks, and insert support iron plates between the steel beam and the bottom of the original floor slab. Then, use high-strength polymer mortar to fill the joints throughout the length.

[0055] The loading structure is as Figure 3 shown. A support platform is tightly connected to the lower part at the mid-span of the steel beam. Jacks are placed at both ends of the support platform, and there are cushion steel plates clamped between the jacks and the ground of the existing floor slab.

[0056] The original floor slab is jacked upwards in reverse, with the steel beam as the jacking support point. The jacking amount is in accordance with Articles 9.3.5 - 9.3.6, Page 79 of the "Technical Code for Strengthening of Existing Building Foundation and Subgrade" JGJ123 - 2000. The maximum jacking value for each jacking in the fourth section of the jacking project does not exceed 10 mm. Considering the influence of the sequence of positions on the structure, the jacking amount is limited according to the allowable structural deformation of 0.003 - 0.005L. If the maximum spacing of the jacks is 1.2 m, then the allowable structural deformation is (0.003 - 0.005) x 1200 = 3.6 - 6.0 mm. Fine cracks have appeared in the original floor slab due to the load before reinforcement. By jacking in reverse, the cracks in the original floor slab are reduced or even closed, and the original floor slab generates an upward camber to offset part of the load deflection of the original floor slab. The subsequent added reinforcement components can also be stressed in a timely manner, thus improving the mechanical properties of the original floor slab structure and increasing the bearing capacity of the original floor slab.

[0057] S8: Painting. After the installation of the steel beam is completed, for the pre-reserved connection plates, bearing anchor plates and other parts, use the same process as the steel beam for painting: Conduct rust removal treatment on the surface, and the rust removal grade should meet the design requirements. Then, apply anti-corrosion and fire-proof coatings. The variety, number of layers, thickness, etc. of the coatings should meet the design requirements. The anti-corrosion and fire-proof coatings should be applied evenly, without missed painting or running.

[0058] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and modifications can be made. These improvements and modifications made under the above assumptions should also be regarded as the protection scope of the present invention.

Claims

1. A construction method for adding a steel beam to an existing frame structure, characterized in that: It includes the following steps: S1: Positioning and setting out: Pop the position lines of the support anchor plate and U-shaped hoops according to the requirements; S2: Treatment of the existing frame beam and the base layer of the existing floor slab; S3: Paste and press-fix the steel plate U-shaped hoops on the existing frame beam, and the steel plate U-shaped hoops are close to the support anchor plate; S4: Fabrication and installation of the support anchor plate; S5: Fabrication of the post-added steel beam on the ground and lifting and installation; S6: Sealing and injecting glue for the support anchor plate: Seal the periphery of the support anchor plate with sealant glue, and inject the steel-bonding injection glue into the gap between the support anchor plate and the concrete of the existing frame beam.

2. The construction method of adding a steel beam to an existing frame structure according to claim 1, characterized in that: The said S4: Fabrication and installation of the support anchor plate includes: S4-1: Surface treatment of the concrete of the existing frame beam; S4-2: Drilling and implanting bolts; Use a reinforced concrete protective layer tester to find out the reinforcement layout of the concrete of the existing frame beam to avoid touching the reinforcement during drilling, mark the positions where drilling is required, and implant bolts after the holes are drilled; S4-3: Moulding and fabricating the support anchor plate; Cut the anchor plate according to the actual layout on the site concrete, use extruded polystyrene board to mould the bolts implanted on the site, and punch holes for the newly added support anchor plate to be installed; S4-4: Install the support anchor plate; First apply steel-bonding glue around the bolts, then fix the support anchor plate on the bolts, and ensure the gap between the support anchor plate and the concrete surface to ensure the thickness of the injection glue layer.

3. The construction method of adding a steel beam to an existing frame structure according to claim 1, characterized in that: The said S5: Fabrication of the post-added steel beam on the ground and lifting and installation includes: S5-1: Cutting the section steel beam: According to the design dimensions and shape of the section steel beam and combining with the on-site actual situation, use gas cutting or plasma cutting machine to cut the section steel beam on the site to ensure accurate cutting dimensions; S5-2: Assembling and drilling holes: Lay the cut section steel beam flat on the ground, temporarily fix the connecting plate to the end web of the section steel beam by spot welding, and use an electromagnetic drill to drill holes. After the hole opening is completed, knock off the connecting plate; S5-3: Install the section steel beam; After the section steel beam is processed, use a special section steel lifting machine to lift it in place; Fix the connecting plate to the end web of the section steel beam with high-strength bolts. After adjusting the position of the section steel beam, weld the connecting plate to the support anchor plate. After the weld cools down, tighten the high-strength bolts.

4. The construction method of adding a steel beam to an existing frame structure according to claim 1, characterized in that: It also includes S7: Preloading the section steel beam and inserting support steel plates; After meeting the curing time of the steel-bonding injection glue in the support anchor plate, preload the existing floor slab through a jack at the mid-span of the section steel beam, insert support iron plates between the section steel beam and the bottom of the original floor slab, and use high-strength polymer mortar to fill the joints throughout the length.

5. The construction method of adding a post - installed steel beam to an existing frame structure according to claim 4, characterized in that: The curing time of the said steel-bonding injection glue is not less than 3 days.

6. The construction method of adding a steel beam to an existing frame structure according to claim 2, characterized in that: After punching holes in the moulding and fabricating the support anchor plate in S4-3, rust removal and roughening treatment are carried out on the bonding surface of the support anchor plate with a polishing grinder or a wire brush grinder, and the grinding lines should be perpendicular to the stress direction of the support anchor plate; Wipe the surface of the support anchor plate clean with absorbent cotton dipped in acetone.

7. The construction method of adding a steel beam to an existing frame structure according to claim 2, characterized in that: In the said S4-4: Installing the support anchor plate, the gap between the support anchor plate and the concrete surface > 3mm.

8. A construction method for adding a steel beam to an existing frame structure according to claim 3, characterized in that: The said special section steel lifting machine is a kind of air duct automatic lifting and hoisting machine disclosed in CN218231723U.

9. The construction method of adding a steel beam to an existing frame structure according to claim 3, characterized in that: In the said S5-3: Installing the section steel beam, the connecting plate and the support anchor plate are welded by carbon dioxide gas shielded welding.

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