Construction method of cantilever structure

Abstract

The application provides a cantilever structure construction method, and relates to the field of building construction; wherein the cantilever structure construction method comprises the following steps: constructing a plurality of cantilever beams on a second floor above a first floor, and fixing each cantilever beam to a main structure of the second floor, and at least part of the cantilever beams extends into the main structure of the second floor by one span; erecting a steel platform on the first floor, and fixing the steel platform to the main structure of the first floor; erecting a scaffold on the steel platform, and then installing a suspending rod and a suspending formwork on the scaffold to the cantilever beams; pouring concrete into the suspending formwork, and after the concrete is coagulated, the suspending formwork, the scaffold and the steel platform are removed; the cantilever structure is self-bearing by the connection of the cantilever beams and the second floor, and the load of the cantilever structure is not transmitted to the scaffold and the steel platform, so that the construction process is simplified, and the construction efficiency is improved under the premise of meeting the safety requirement.

Description

Technical Field

[0001] This application relates to the field of building construction, and more specifically, to a method for constructing cantilever structures. Background Technology

[0002] Traditional cantilever structure construction mainly relies on two techniques: erecting a full-span scaffold or an I-beam formwork platform. The cantilever structure transfers the load through the scaffold or I-beam formwork platform, thus requiring high load-bearing capacity. In addition, full-span scaffolds consume a lot of materials, requiring various uprights, crossbars, and scissor frames, which not only makes installation difficult and construction costs high, but also requires the scaffold to be erected from the ground up to the cantilever structure, which cannot guarantee construction safety. The cantilever I-beam formwork platform uses I-beams to build the platform, which is relatively complex in structure and has a high degree of difficulty in hoisting and dismantling, which does not conform to the concept of fast, safe, and efficient on-site construction. Summary of the Invention

[0003] The purpose of this application is to provide a construction method for cantilever structures that simplifies the construction process, improves construction efficiency, reduces erection costs, achieves self-supporting capabilities, and ensures high safety.

[0004] In a first aspect, the present invention provides a method for constructing a cantilever structure, comprising:

[0005] Multiple cantilever beams are constructed on the second floor above the first floor, and each cantilever beam is fixed to the main structure of the second floor, with at least a portion of the cantilever beams extending into the main structure of the second floor by one span.

[0006] A steel platform is erected on the first floor, and the steel platform is fixed to the main structure of the first floor;

[0007] Scaffolding is erected on the steel platform, and then hanging rods and formwork are installed on the cantilever beam using the scaffolding;

[0008] Concrete is poured into the suspended formwork, and after the concrete has set, the suspended formwork, the scaffolding, and the steel platform are removed.

[0009] In an optional implementation, the length of the cantilever beam is prefabricated according to the design drawings, including: bolting adjacent I-beams together with fixing plates, and reserving welding openings at the connection of adjacent I-beams.

[0010] In an optional embodiment, an ear plate is pre-embedded in the main structure of the second floor, and the ear plate and the welded opening are connected by turnbuckles respectively.

[0011] In an optional implementation, the erection of the steel platform includes: installing multiple main ribs along the edge perpendicular to the first floor, then installing multiple secondary ribs along the direction perpendicular to the main ribs, and finally laying steel plates on the secondary ribs.

[0012] In an optional implementation, the main joists, the secondary joists, and the steel plates are installed in order from the edge of the first floor outwards, with appropriate safety measures in place.

[0013] In an optional implementation, the outward extension lengths of both the steel platform and the scaffolding are greater than the length of the cantilever beam compared to the outward extension length of the cantilever beam.

[0014] In an optional embodiment, a portion of the cantilever beam is welded to the hanger rod, and the portion of the cantilever beam is fixed to the first template of the hanging formwork by binding with steel bars before concrete is poured. After the concrete has set, the first template is removed to obtain the main beam.

[0015] In an optional embodiment, the main beam and the main structure of the second floor are tied together and fixed, then multiple first support members are installed above the main beam in a direction perpendicular to the main beam, and finally multiple second support members are installed above the first support members in a direction perpendicular to the first support members.

[0016] In an optional embodiment, the remaining cantilever beam and the second formwork of the suspended formwork are fixed together with steel bars and then connected to the second support member by a suspension rod to form an integral whole. Concrete is then poured, and after the concrete has set, the second formwork, the first support member and the second support member are removed to obtain the secondary beam and the bottom slab.

[0017] In an optional embodiment, a third support and a third template are installed within multiple intervals formed by the main beam, the secondary beam, and the bottom plate, and concrete is poured on the third template to obtain the top plate.

[0018] Compared to existing technologies, the beneficial effects of this application are:

[0019] This application achieves the self-supporting goal of the cantilever structure by connecting the cantilever beam to the second floor, avoiding the transfer of load from the cantilever structure to the scaffolding and steel platform. Therefore, the scaffolding serves as the construction space for the suspended formwork, and the fixing of the steel platform to the first floor is sufficient to meet the load-bearing requirements. Under the premise of meeting safety requirements, the construction process is simplified and the construction efficiency is improved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This embodiment shows a diagram illustrating the positional relationship between the first and second floors.

[0022] Figure 2 A schematic diagram of the connection between the second floor and the cantilever structure in this embodiment is shown (some components are omitted);

[0023] Figure 3 A schematic diagram of the cantilever beam structure in this embodiment is shown;

[0024] Figure 4 A schematic diagram of the ear plate structure in this embodiment is shown;

[0025] Figure 5 A schematic diagram of the turnbuckle structure in this embodiment is shown;

[0026] Figure 6 A schematic diagram of the guy rope installation in this embodiment is shown;

[0027] Figure 7 A schematic diagram of the connection between the first floor and the steel platform in this embodiment is shown (some components are omitted);

[0028] Figure 8 This diagram illustrates the connection between the I-beam and the formwork and lifting rod in this embodiment.

[0029] Figure 9 This diagram illustrates the connection between the main beam and the suspended formwork in this embodiment.

[0030] Figure 10 This diagram illustrates the connection between the main beam, secondary beam, and suspended formwork in this embodiment.

[0031] Figure 11 This embodiment shows a schematic diagram of the main beam removal. Figure 1 ;

[0032] Figure 12 This embodiment shows a schematic diagram of the main beam removal. Figure 2 ;

[0033] Figure 13 A flowchart of the cantilever structure construction method of this embodiment is shown.

[0034] Explanation of key component symbols:

[0035] 100 - First floor; 200 - Second floor; 210 - Ear plate; 300 - Cantilever beam; 301 - Main beam; 302 - Secondary beam; 303 - Bottom plate; 304 - Top plate; 310 - I-beam; 311 - Web plate; 312 - Flange plate; 313 - Welded joint; 320 - First fixing plate; 330 - Second fixing plate; 340 - Third fixing plate; 350 - First bolt; 360 - Second bolt; 370 - Lifting hole; 400 - Turnbuckle; 50 0-Guide rope; 510-Main tension rope; 520-Secondary tension rope; 530-Rope clip; 540-Lifting ring; 600-Steel platform; 610-Main support; 611-Lifting lug; 620-Secondary support; 630-U-shaped buckle; 700-Lifting formwork; 710-First support component; 720-Second support component; 730-Third support component; 740-Timber; 750-Double channel steel; 800-Lifting rod; 810-High-strength bolt; 910-Hand chain hoist; 920-Lifting rope. Detailed Implementation

[0036] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0037] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] This embodiment is applicable to the construction of cantilever structures such as eaves, balconies, and corridors, enabling buildings to obtain open spaces and extend usable spaces. This embodiment is especially suitable for ultra-long cantilever structures with a cantilever length exceeding 4 meters.

[0042] It is worth noting that the length referred to in this embodiment is the distance extending outward from the edge of the floor slab.

[0043] This embodiment can improve construction efficiency, reduce construction costs, and increase project value while ensuring safety, thus addressing the shortcomings of traditional construction methods.

[0044] Please base on Figure 13 Please refer to the following figures.

[0045] Please see Figure 1 and Figure 2 This embodiment provides a construction method for a cantilever structure, including the following steps:

[0046] S100. Construct multiple cantilever beams 300 on the second floor 200 above the first floor 100, and fix each cantilever beam 300 to the main structure of the second floor 200, and at least part of the cantilever beam 300 extends into the main structure of the second floor 200 by one span.

[0047] The construction building includes multiple floors, and the cantilever structure is located at least on the second floor or above. In this embodiment, the following settings can be made: the construction building includes a total of fifteen floors, and the cantilever structure is located on the tenth floor, that is, the second floor 200 is the tenth floor, and the first floor 100 is the ninth floor.

[0048] First, please refer to Figure 3 For the length of the cantilever beam 300, the construction personnel need to prefabricate the length of the cantilever beam 300 according to the design drawings, including: bolting between adjacent I-beams 310 through fixing plates, and reserving a welding cutout 313 at the connection of adjacent I-beams 310.

[0049] For example, if the design drawings specify that the length of the cantilever beam 300 is 5 meters, while the standard length of the I-beam 310 is 2.5 meters, then the two I-beams 310 need to be spliced ​​together to meet the construction requirements.

[0050] Each I-beam 310 includes a web 311 and two flanges 312, and the fixing plates include a first fixing plate 320, a second fixing plate 330 and a third fixing plate 340.

[0051] There are two first fixing plates 320, which are located on both sides of the web plate 311 respectively. The first bolts 350 are vertically inserted into the two fixing plates and the two web plates 311 between the two fixing plates.

[0052] There are eight second fixing plates 330 and eight third fixing plates 340. Each pair of second fixing plates 330 is located on both sides of a corresponding wing plate 312. Each pair of third fixing plates 340 clamps two second fixing plates 330 on the same side. The second bolts 360 are vertically inserted through the two third fixing plates 340 and the two second fixing plates 330 between the two third fixing plates 340. The two third fixing plates 340 and the two second fixing plates 330 form a lifting hole 370.

[0053] Since the first bolt 350 and the second bolt 360 are set perpendicularly, the two I-beams 310 form a stable fixed connection, reducing the bending moment at the node, improving safety and load-bearing capacity, and providing feasibility for the self-supporting of the cantilever structure.

[0054] In addition, in this embodiment, a 45° inclined welding slit 313 is cut on the two flanges 312 of one of the I-beams 310, and the inclined surfaces of the welding slit 313 face the same direction.

[0055] Secondly, please base on Figure 3 For further information Figure 1 , Figure 4 and Figure 5 Ear plates 210 are pre-embedded in the main structure of the second floor 200, and turnbuckles 400 are used to connect the ear plates 210 and the welded opening 313 respectively, thereby achieving the purpose of fixing the cantilever beam 300 to the main structure of the second floor 200. Moreover, the turnbuckles 400 can be adjusted at both ends, making them more flexible and convenient to use.

[0056] The ear plate 210 has multiple holes for connecting multiple turnbuckles 400.

[0057] In some other embodiments, please refer to Figure 1 and Figure 6 The cantilever beam 300 can also be fixed to the main structure of the second floor 200 by means of guy rope 500.

[0058] The guy rope 500 includes a main tension rope 510, a secondary tension rope 520, and rope clamps 530. The cross-sectional area of ​​the main tension rope 510 is larger than that of the secondary tension rope 520, and the secondary tension rope 520 is located between the bend of the main tension rope 510 and the rope clamp 530. It can be understood that there are multiple rope clamps 530. At the position between two rope clamps 530, the secondary tension rope 520 forms a safety bend relative to the main tension rope 510, thereby strengthening the tension capacity of the guy rope 500.

[0059] Please refer to further information. Figure 3 The guy rope 500 is made of smooth steel wire rope with an engineering tensile strength of 1550Mpa and a diameter of 15.5mm. One end of the guy rope 500 is equipped with a lifting ring 540, which is made of φ20 round steel. The length of the guy rope 540 anchored into the beam of the main structure is greater than 30d (bent anchor), and the angle between the guy rope 500 and the horizontal plane shall not be less than 45°. The upper pull node is connected to the lifting hole 370 of the cantilever beam 300.

[0060] Finally, in this embodiment, the cantilever beam 300 can be welded and assembled with the main structure along with the main structure. In this case, if all the cantilever beams 300 are set to extend one span into the main structure of the second floor 200, it can be ensured that the two sides can achieve a certain balance effect during the pre-hoisting, which facilitates the safe hoisting of the cantilever beam 300 and the main structure.

[0061] It is worth noting that a span refers to the distance between two supports on both sides of the main structure.

[0062] In some other embodiments, if the cantilever beam 300 cannot be hoisted in advance synchronously with the main structure due to external constraints, the location of the weld of the cantilever beam 300 (i.e., at the weld section 313), the length of the reserved steel reinforcement, and the location of the concrete construction joint should be fully considered. The three should not be on the same cross-section to prevent the steel reinforcement and concrete from breaking due to the weld of the cantilever beam 300, thereby improving the safety factor and load-bearing capacity.

[0063] Please see Figure 7 .

[0064] S200. Erect a steel platform 600 on the first floor 100 and fix the steel platform 600 to the main structure of the first floor 100.

[0065] Multiple main ribs 610 are installed along the edge perpendicular to the first floor 100, and then multiple secondary ribs 620 are installed along the direction perpendicular to the main ribs 610. Finally, steel plates are laid on the secondary ribs 620. The main ribs 610 use Q335 H-beams, and the secondary ribs 620 use 20a Q235 I-beams 310. The steel plates are 3mm thick Q235 patterned steel plates.

[0066] The main joists 610, secondary joists 620, and steel plates are installed in the order from the edge of the first floor 100 outwards, and safety measures are taken.

[0067] In practical applications, U-shaped buckles 630 can be pre-embedded within 100 meters of the first floor. The main rib 610 can be fixed using the U-shaped buckles 630. The secondary rib 620 is welded above the main rib 610. Finally, the steel plate is laid on top of the secondary rib 620.

[0068] Understandably, please refer to the following as well. Figure 2 and Figure 7 The cantilever beam 300 is constructed on the second floor at 200 meters, and the steel platform 600 is constructed on the first floor at 100 meters. Therefore, the construction of the cantilever beam 300 and the steel platform 600 does not affect each other and can be flexibly arranged according to the construction schedule of different construction personnel. The cantilever beam 300 can be constructed first, the steel platform 600 can be constructed first, or both cantilever beam 300 and steel platform 600 can be constructed simultaneously.

[0069] Please refer to the following: Figure 2 , Figure 7 and Figure 8 .

[0070] S300. Erect scaffolding on the steel platform 600, and then use the scaffolding to install the hanging rod 800 and the hanging formwork 700 on the cantilever beam 300.

[0071] First, compared to the outward extension length of the cantilever beam 300, the outward extension lengths of the steel platform 600 and the scaffolding are both greater than the length of the cantilever beam 300.

[0072] Specifically, the scaffolding is erected using precast steel pipes. If the modularity is insufficient, it can be reinforced locally using steel pipes with couplers. This embodiment is configured as follows: the spacing between the bottom working platforms is 1.5×1.5×2m, the outer scaffolding dimensions are 0.6×1.5×2m, and the inner and outer scaffolding should be connected as a whole to ensure overall stability. A 1m space is reserved for the outer scaffolding, meaning the working platform dimensions extend 1m beyond the cantilevered structure area.

[0073] Compared to existing technologies, the scaffolding and steel platform 600 in this embodiment only serve as the operating space for construction, bearing the load of the suspended formwork 700 and the load of operators and equipment, without bearing the load from the cantilever structure. Therefore, the steel platform 600 does not need to be equipped with diagonal bracing or other reinforcement measures, and its structure is simpler. Under the premise of ensuring operational safety, the amount of high-altitude splicing work is reduced.

[0074] In addition, due to the reduced load from the cantilever structure, the settlement and deflection of the steel platform 600 are also smaller, the steel platform 600 is less prone to deformation under stress, the relative position of the cantilever structure is easier to control, the welding quality of the cantilever structure is improved, and thus the flatness of the cantilever structure is guaranteed.

[0075] Secondly, a portion of the cantilever beam 300 is welded to the hanger 800, and this portion of the cantilever beam 300 is fixed to the first formwork of the hanging formwork 700 by binding with steel bars before concrete is poured. After the concrete has set, the first formwork is removed to obtain the main beam 301.

[0076] In this embodiment, when the hanger rods 800 are customized, the spacing between the hanger rods 800 should be slightly larger than the width of the I-beam 310 in the cantilever beam 300, and M20 high-strength bolts 810 are used at the connection.

[0077] The main beam 301 and the main structure of the second floor 200 are connected and fixed by turnbuckles 400.

[0078] Please refer to the following: Figure 9 and Figure 10 Then, multiple first support members 710 are installed above the main beam 301 in a direction perpendicular to the main beam 301, and finally multiple second support members 720 are installed above the first support members 710 in a direction perpendicular to the first support members 710.

[0079] The first support member 710 serves as the back rib for supporting the formwork system and can be made of 36a I-beam. The second support member 720 is used to support the formwork system and can be made of 22a I-beam.

[0080] After the remaining cantilever beam 300 and the second formwork of the suspended formwork 700 are fixed together with steel bars, they are connected to the second support member 720 through the hanger 800 to form a whole. Then concrete is poured. After the concrete sets, the second formwork, the first support member 710 and the second support member 720 are removed to obtain the secondary beam 302 and the bottom plate 303.

[0081] The third support member 730 and the third template are installed in the multiple intervals formed by the main beam 301, the secondary beam 302 and the bottom plate 303, and concrete is poured on the third template to obtain the top plate 304.

[0082] Therefore, the top plate 304 and the bottom plate 303, along with the main beam 301 and the secondary beam 302 located between the top plate 304 and the bottom plate 303, together form a cantilever structure. The weight during the formwork hoisting process is borne by the main beam 301 and the secondary beam 302. Therefore, this embodiment does not require the use of scaffolding for load transfer, making the construction scheme more effective.

[0083] For further information, please refer to [link / reference]. Figure 8 To reinforce the suspended formwork 700, the following settings are made in this embodiment: five secondary ribs × 100 timber 740 and main ribs # double channel steel 750 are set on the bottom formwork; secondary ribs × 100 timber 740 and main ribs double round steel pipes are set on the side formwork, and four M14 tie bolts are set.

[0084] Please refer to further information. Figure 7 The suspended formwork 700 system in this embodiment is simple and does not affect the structural construction within the floor. Furthermore, the steel platform 600 is easy to use and has a short welding period, which greatly saves on construction time and corresponding cost.

[0085] S400. Pour concrete inside the suspended formwork 700. After the concrete has set, remove the suspended formwork 700, scaffolding, and steel platform 600.

[0086] S300 provides a detailed step-by-step description of the dismantling work, and the steel platform 600 should be dismantled by cutting and dismantling in the order of steel plate, secondary rib 620, and main rib 610. The secondary rib 620 is either directly hoisted by a tower crane or cut and then directly dismantled by a construction unit.

[0087] Please see Figure 11 and Figure 12 The main beam 610 was dismantled using a tower crane and a hand-operated hoist 910. The dismantling method of one of the main beams 610 is further explained below:

[0088] S410. Fix a hand chain hoist 910 on the main structure above the first floor 100;

[0089] S420. Weld lifting lugs 611 to both ends of the main beam 610. The lifting lugs 611 on the outer side are fixed to the lifting rope 920 of the tower crane, and the lifting lugs 611 on the inner side are fixed to the hand chain hoist 910.

[0090] S430. Cut off the connection between the main rib 610 and the first floor 100 along the edge of the first floor 100, release the hand chain hoist 910, and the inner main rib 610 slowly descends until the main rib 610 is placed in a vertical position.

[0091] S440. The hoisting rope 920 rises and drives the main beam 610 to the cantilever structure. The hand chain hoist 910 is released. With the cooperation of the construction personnel, the hoisting rope 920 is gradually lowered, and the construction personnel pull the main beam 610 to the second floor 200 and place it.

[0092] Furthermore, after the secondary joists 620 and the main joists 610 are removed, the inner layer of the steel platform 600 is dismantled, and the remaining main joists 610 located on the first floor 100 and the embedded U-shaped parts that fix the main joists 610 are cut. Finally, the concrete surface is repaired.

[0093] This embodiment makes full use of the structure's own bearing capacity, minimizing the construction load transmitted to the steel platform 600 below the cantilever structure during concrete pouring. While increasing construction safety, it simplifies the platform structure, improves construction efficiency, makes construction operations simpler, improves quality control, and reduces construction costs.

[0094] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0095] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A construction method for a cantilever structure, characterized in that, include: Multiple cantilever beams are constructed on the second floor above the first floor, and each cantilever beam is fixed to the main structure of the second floor, with at least a portion of the cantilever beams extending into the main structure of the second floor by one span. While constructing the cantilever beam, a steel platform is erected on the first floor and fixed to the main structure of the first floor; Scaffolding is erected on the steel platform, with a reserved space between the scaffolding and the cantilever beam. Compared to the outward extension length of the cantilever beam, the outward extension lengths of both the steel platform and the scaffolding are greater than the length of the cantilever beam. Hanging rods and formwork are then installed on the scaffolding and onto the cantilever beam. Concrete is poured into the suspended formwork. After the concrete sets, the suspended formwork, the scaffolding, and the steel platform are removed to obtain a cantilever structure formed by the top slab, the bottom slab, and the main beams and secondary beams located between the top slab and the bottom slab. The length of the cantilever beam is prefabricated according to the design drawings, including: bolting adjacent I-beams together with fixing plates, and reserving welding openings at the connection of adjacent I-beams; Ear plates are pre-embedded in the main structure of the second floor, and the ear plates and the welded opening are connected by turnbuckles respectively. Each I-beam consists of a web and two flanges; The fixing plate includes a first fixing plate, a second fixing plate, and a third fixing plate; The webs of two adjacent I-beams are connected by two first fixing plates. The two first fixing plates are located on both sides of the webs respectively, and the first bolts are perpendicularly inserted into the two fixing plates and the two webs between the two fixing plates. The two flanges of two adjacent I-beams are connected by eight second fixing plates and eight third fixing plates. Each pair of second fixing plates is located on both sides of the corresponding flange. Each pair of third fixing plates clamps the two second fixing plates on the same side. The second bolts are vertically inserted through the two third fixing plates and the two second fixing plates between the two third fixing plates. The two third fixing plates and the two second fixing plates form a lifting hole. One of the I-beams has two flanges cut to form a 45° inclined weld cut, and the inclined surfaces of the weld cut face the same direction. Ear plates are pre-embedded in the main structure of the second floor, and then the ear plates and welding slots are connected by turnbuckles to fix the cantilever beam to the main structure of the second floor.

2. The construction method for cantilever structures as described in claim 1, characterized in that, The construction of the steel platform includes: installing multiple main ribs along the edge perpendicular to the first floor, then installing multiple secondary ribs along the direction perpendicular to the main ribs, and finally laying steel plates on the secondary ribs.

3. The construction method for cantilever structures as described in claim 2, characterized in that, The main joists, secondary joists, and steel plates are installed in order from the edge of the first floor outwards, with appropriate safety measures in place.

4. The construction method for cantilever structures as described in claim 1, characterized in that, A portion of the cantilever beam is welded to the hanger rod, and this portion of the cantilever beam is fixed to the first template of the hanging formwork by binding with steel bars before concrete is poured. After the concrete has set, the first template is removed to obtain the main beam.

5. The construction method for cantilever structures as described in claim 4, characterized in that, The main beam and the main structure of the second floor are tied together and fixed. Then, multiple first support members are installed above the main beam in a direction perpendicular to the main beam. Finally, multiple second support members are installed above the first support members in a direction perpendicular to the first support members.

6. The construction method for cantilever structures as described in claim 5, characterized in that, After the remaining cantilever beam and the second formwork of the suspended formwork are fixed together with steel bars, they are connected to the second support member by a suspension rod to form a whole. Then concrete is poured. After the concrete sets, the second formwork, the first support member and the second support member are removed to obtain the secondary beam and the bottom slab.

7. The construction method for cantilever structures as described in claim 6, characterized in that, A third support and a third template are installed in the multiple intervals formed by the main beam, the secondary beam and the bottom plate, and concrete is poured on the third template to obtain the top plate.

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