Construction method and construction system for cantilever eave of high-rise building

Abstract

The invention discloses a construction method and system for a cantilever eave of a high-rise building, the top of the high-rise building comprises a roof floor slab, the roof floor slab comprises a first side and a second side opposite to the first side, the cantilever eave is arranged in the area above the first side, and the cantilever eave is arranged in the area above the second side. The overhanging eaves comprise an overhanging eave above a house floor slab and an overhanging part overhanging eave, a roof beam is arranged on the second side, a first anchor ring is pre-embedded in the top of the roof beam, a plurality of pieces of parallel profile steel are arranged on the upper surface of the first side of the roof floor slab in the X-axis direction, the overhanging eave above the house floor slab is constructed above the edge area, and a second anchor ring is pre-embedded in the second side of the roof floor slab. A second anchor ring is arranged at the highest eave beam, and the first anchor ring and the second anchor ring are connected through inhaul cables and tensioned to a certain tensile force; the overhanging eave of the overhanging part is constructed in the area above the section steel extending out of the roof floor slab; and a parapet wall is constructed beside the eave column.

Description

Technical Field

[0001] The present invention relates to the field of high-rise building construction, and in particular to a construction method and a construction system for cantilevered eaves of a high-rise building. Background Art

[0002] High-rise buildings offer advantages such as large volume ratios, high land utilization rates, and low unit costs, but their facades cannot exhibit significant fluctuations. Eaves are a crucial element of traditional architecture, not only enhancing the building's beauty but also carrying rich cultural connotations. The challenge in integrating cantilevered eaves with high-rise architecture, ensuring that the building retains its traditional charm and appeal while maintaining a contemporary and technological feel, presents a technical challenge. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method and construction system for cantilevered eaves of high-rise buildings, so as to solve the problems existing in the above-mentioned prior art.

[0004] In order to solve the above problems, a first aspect of the present invention provides a method for constructing a cantilevered eave of a high-rise building, characterized in that the top of the high-rise building includes a roof slab, the roof slab includes a first side and a second side opposite to the first side, the cantilevered eaves are provided in an area above the first side, the cantilevered eaves include a cantilevered eave above the roof slab and a cantilevered eaves of a cantilevered portion, the second side is provided with a roof beam, the roof beam and the length direction of the cantilevered eaves are parallel to the X-axis direction, and the construction method comprises the following steps:

[0005] Step 1: pre-embed a first anchor ring at the top of the roof beam, arrange a plurality of parallel steel sections along the X-axis direction on the upper surface of the first side of the roof slab, wherein the length direction of the steel sections is consistent with the Y-axis direction, a portion of the steel sections is arranged on the first side of the roof slab, and another portion of the steel sections extends out of the first side of the roof slab;

[0006] Step 2: In the overlapping area between the section steel and the roof slab, the portion of the section steel close to the edge of the roof slab is the edge area and the remaining portion is the inner area; a cantilevered eave above the roof slab is constructed above the edge area; the cantilevered eave above the roof slab includes a vertically supported eaves column, a portion of the eaves board and an eaves beam; a portion of the eaves board is arranged above the eaves column and is gradually lowered from the inside to the outside of the high-rise building; the eaves beam is arranged at a height of the eaves board and is arranged along the X-axis in its length direction; a second anchor ring is arranged at the highest eaves beam; a cable is used to connect the first anchor ring and the second anchor ring respectively and tighten them to a certain tension;

[0007] Step 3: constructing the cantilevered eaves in the area above the steel section extending out of the roof slab, wherein the cantilevered eaves include another portion of the eaves board and another portion of the eaves beam, wherein the other portion of the eaves board continues to extend obliquely along the eaves board of the cantilevered eaves above the roof slab, and the other portion of the eaves board is provided with another portion of the eaves beam, and the length direction of the other portion of the eaves beam is arranged along the X-axis;

[0008] Step 4: dismantle the formwork, protective device and the cables set up for the cantilevered eaves above the roof floor constructed in step 2, dismantle the formwork and protective device set up for the cantilevered eaves of the cantilevered part constructed in step 3, and then construct a parapet next to the eaves column.

[0009] Optionally, in step 2, a ballast is placed in the inner area of ​​the steel section.

[0010] Optionally, F N is the tension of the cable, θ is the horizontal angle between the cable and the roof slab, F Ny F N The vertical component of force, F1 is the weight of the weight, L1 is the distance between F1 and the edge support point of the roof floor, L2 is F Ny The distance between the line of action and the edge support point of the roof slab, G1 is the deadweight of the cantilevered eaves above the roof slab, F2 is the deadweight of the formwork frame erected for the construction of the cantilevered eaves above the roof slab, L3 is the distance between the point of action of the combined forces of G1 and F2 and the edge support point of the roof slab, G2 is the deadweight of the cantilevered eaves of the cantilevered part, F3 is the deadweight of the formwork frame erected for the construction of the cantilevered eaves of the cantilevered part, L4 is the distance between the point of action of the combined forces of G2 and F3 and the edge support point of the roof slab, where

[0011] When the effect of the cable is not considered,

[0012]

[0013] The gravity F1 of the ballast must satisfy:

[0014]

[0015] When the effect of the ballast is not considered,

[0016]

[0017] The tension F of the cable N Need to meet:

[0018]

[0019] Optionally, the specifications of the steel section are determined according to the deadweight G2 of the cantilevered eaves and the deadweight F3 of the formwork, specifically satisfying:

[0020] The design value of the bearing capacity of a single steel section is F y Need to meet:

[0021]

[0022] Wherein, S is the spacing of the steel sections, and n is the number of steel sections;

[0023] Section bending modulus W of steel y Need to meet:

[0024]

[0025] Where f is the design value of the steel section’s bending strength.

[0026] Optionally, the steel section is hot-rolled H-shaped steel, the spacing S of the steel sections is 0.8~1.5m, the cross-sectional height H is 200~400mm, and the length of the steel section extending out of the first side of the roof floor does not exceed 2 / 3 of the total length of the steel section.

[0027] Optionally, the embedding depth and specifications of the first anchor ring and the second anchor ring are determined according to the cable tension F N Confirm, specifically meet:

[0028] Anchorage length L of anchor ring a Need to meet:

[0029]

[0030] Wherein, d is the diameter of the steel bars of the first anchor ring and the second anchor ring, and τb is the bond strength between concrete and steel bars;

[0031] Anchor ring steel cross-sectional area A s Need to meet:

[0032]

[0033] Among them, f y is the design value of steel bar tensile strength.

[0034] Optionally, the first anchor ring and the second anchor ring are made of HRB400 grade steel bars with a diameter of not less than 20 mm and a buried depth of not less than 30 times the diameter of the steel bars, and a 180° hook is provided at the end of the anchor ring.

[0035] Optionally, the cable is made of steel strand or high-strength steel wire bundle, and its breaking strength standard value F pk Need to meet:

[0036]

[0037] The connection between the cable and the anchor ring adopts hot cast anchor or cold extruded anchor.

[0038] A second aspect of the present invention provides a construction system for a cantilevered eave of a high-rise building, the construction system comprising a high-rise building and a roof slab disposed on top of the high-rise building, the roof slab comprising a first side and a second side opposite to the first side, the cantilevered eaves being disposed in an area above the first side, the cantilevered eaves comprising a cantilevered eave above the roof slab and a cantilevered eave of a cantilevered portion, the second side being provided with a roof beam, the roof beam being parallel to the length direction of the cantilevered eaves along the X-axis direction;

[0039] A first anchor ring is embedded in the top of the roof beam, and a plurality of parallel steel sections are arranged along the X-axis direction on the upper surface of the first side of the roof slab, wherein the length direction of the steel sections is consistent with the Y-axis direction, a portion of the steel sections is arranged on the first side of the roof slab, and another portion of the steel sections extends out of the first side of the roof slab.

[0040] In the overlapping area of ​​the steel section and the roof slab, the portion of the steel section close to the edge of the roof slab is the edge area and the remaining portion is the inner area. A cantilevered eaves above the roof slab is provided above the edge area. The cantilevered eaves above the roof slab include vertically supported eaves columns, part of the eaves slab and eaves beams. Part of the eaves slabs are arranged above the eaves columns and are gradually lowered from the inside to the outside of the high-rise building. The eaves beams are arranged at a height of the eaves slabs and are arranged along the X-axis in their length direction. A second anchor ring is provided at the highest eaves beam. The first anchor ring and the second anchor ring are respectively connected by cables and tightened to a certain tension.

[0041] The cantilevered eaves are provided in the upper area of ​​the steel section extending out of the roof slab, and the cantilevered eaves include another part of the eaves plate and another part of the eaves beam. The other part of the eaves plate continues to extend obliquely along the part of the eaves plate that cantilevers out above the roof slab, and the other part of the eaves plate is provided with another part of the eaves beam, and the length direction of the other part of the eaves beam is arranged along the X-axis.

[0042] Optionally, a ballast is placed in the inner area of ​​the steel section.

[0043] The beneficial effects of the present invention are:

[0044] The method adopts the method of pre-embedded anchor rings on the roof beams, and adopts steel sections as the load-bearing members of the cantilevered eaves. First, the cantilevered eaves above the roof floor (eaves columns, eaves beams and eaves boards on the upper part of the roof floor) are constructed. The cast eaves beams and anchor rings are tightened by cables to form a redundant first anti-overturning system. Then the cantilevered eaves of the cantilevered part are constructed, and finally the parapet part is constructed to complete the construction of the large cantilevered eaves. The present invention changes the traditional ground support mode to an aerial support mode, which has the advantages of not requiring the leveling and hardening of the foundation, not being restricted by the height of the building, and having strong adaptability. The steel sections of the present invention are directly placed on the roof floor, and there is no need to use through-plate bolts for fixing, which effectively avoids the risk of insufficient bearing capacity of the roof floor and the risk of water seepage in the roof caused by the pre-embedded bolts in the roof floor in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a general schematic diagram of a construction method according to an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of a cantilevered eave above a construction roof floor according to an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of a cantilevered eave of a construction cantilever portion according to an embodiment of the present invention;

[0048] Figure 4 A schematic diagram of a parapet wall construction according to an embodiment of the present invention;

[0049] Figure 5 FIG. 1 is a schematic diagram of force analysis according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the objects, features and advantages of the present invention can be more clearly understood. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0051] In the following description, for the purpose of illustrating the various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other cases, well-known devices, components, and techniques associated with this application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0052] References throughout this specification to "one embodiment" or "an embodiment" indicate that a particular feature, component, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, components, or characteristics may be combined in any manner in one or more embodiments.

[0053] In the following description, in order to clearly show the components and working methods of the present invention, many directional words will be used for description, but words such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and should not be understood as restrictive terms.

[0054] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the component must be completely horizontal, but rather that it can be slightly tilted.

[0055] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0056] Example 1

[0057] This embodiment provides a construction method for cantilevered eaves of a high-rise building, referring to Figures 1 to 4 The top of the high-rise building includes a roof slab 1, which includes a first side 14 and a second side 15 opposite to the first side 14. The upper area of ​​the first side 14 is provided with a cantilevered eave 16, which includes a cantilevered eave 161 above the roof slab and a cantilevered eave 162 of the cantilevered portion. The second side 15 is provided with a roof beam 2, and the length direction of the roof beam 2 and the cantilevered eave 16 is parallel to the X-axis direction. The construction method includes the following steps:

[0058] Step 1: Reference Figure 1 and 2A first anchor ring 13 is embedded in the top of the roof beam 2, and a plurality of parallel steel sections 7 are arranged along the X-axis direction on the upper surface of the first side 14 of the roof slab 1. The length direction of the steel sections 7 is consistent with the Y-axis direction. A portion of the steel sections 7 is arranged on the first side 14 of the roof slab 1, and the other portion of the steel sections 7 extends out of the first side 14 of the roof slab; the steel sections 7 are directly placed on the first side 14 of the roof slab 1, and the steel sections 7 are fixed to the roof slab without bolts.

[0059] Step 2: Reference Figure 1 and 2 In the overlapping area between the steel section 7 and the roof slab 1, the portion of the steel section 7 close to the edge of the roof slab 1 is the edge area 17, and the remaining portion is the inner area 18. A cantilevered eaves 161 above the roof slab is constructed above the edge area 17. The cantilevered eaves 161 above the roof slab includes a vertically supported eaves column 4, a portion of the eaves slab 5, and an eaves beam 6. The portion of the eaves slab 5 is arranged above the eaves column 4 and is inclined to gradually decrease from the inside to the outside of the high-rise building. The eaves beam 6 is arranged at a height of the eaves slab 5 and its length direction is arranged along the X-axis. A second anchor ring 13' is provided on the highest eaves beam 6. The first anchor ring 13 and the second anchor ring 13' are respectively connected by a cable 12 and tightened to a certain tension.

[0060] Step 3: Reference Figure 1 and Figure 3 , a cantilevered part of the cantilevered eaves 162 is constructed in the area above the steel section 7 extending out of the roof slab 1. The cantilevered part of the cantilevered eaves 162 includes another part of the eaves board 5 and the eaves beam 6. The other part of the eaves board 5 continues to extend obliquely along the eaves board 5 of the cantilevered eaves 161 above the roof slab. The other part of the eaves board 5 is provided with another part of the eaves beam 6, and the length direction of the other part of the eaves beam 6 is arranged along the X-axis. It can be understood that the eaves board 5 and the eaves beam 6 are constructed in two steps. First, the eaves board 5 and the eaves beam 6 at the cantilevered eaves 161 above the roof slab are constructed, and then the eaves board 5 and the eaves beam 6 of the cantilevered part of the cantilevered eaves 162 are constructed to meet the mechanical properties of anti-overturning.

[0061] Step 4: Reference Figure 1 and Figure 4 After removing the formwork 9, protective devices, and cables 12 erected for the cantilevered eaves 161 above the roof slab during construction in step 2, and the formwork 9 and protective devices erected for the cantilevered eaves 162 during construction in step 3, construct the parapet 3 next to the eaves columns 4. The formwork 9 can be a steel pipe fastener-type formwork, a disc-type formwork, or the like; the protective devices can include a horizontal protective net 10 and a horizontal protective railing 11.

[0062] It should be noted that:

[0063] The X-axis is perpendicular to the paper, the Y-axis is parallel to the paper and horizontal, and the Z-axis is parallel to the paper and vertical.

[0064] With this design, anchor rings are embedded in the roof beams, and steel sections are used as load-bearing components for the cantilevered eaves. First, the cantilevered eaves above the roof slab are constructed (eaves columns, eaves beams, and eaves slabs on the upper part of the roof slab). The cast eaves beams and anchor rings are tightened by cables to form a redundant first anti-overturning system. Then, the cantilevered eaves of the cantilevered part are constructed, and finally, the parapet part is constructed to complete the construction of the large cantilevered eaves. The present invention changes the traditional ground support mode to an aerial support mode, which has the advantages of not requiring the leveling and hardening of the foundation, not being restricted by the height of the building, and having strong adaptability. The steel sections of the present invention are placed directly on the roof slab without the need for through-plate bolts for fixing, effectively avoiding the risk of insufficient bearing capacity of the roof slab and the risk of water seepage in the roof caused by the embedded bolts in the roof slab in the later stage.

[0065] In one embodiment of the present invention, in step 2, a ballast 8 is placed in the inner area 18 of the steel section 7. The ballast 8 can be a heavy object such as a sandbag, steel, or brick.

[0066] With such a design, a second anti-overturning system is formed by the ballast.

[0067] In one embodiment of the present invention, referring to Figures 1 to 5 The conditions that the first anti-overturning system and the second anti-overturning system need to meet are as follows:

[0068] F N is the tension of the cable 12, θ is the horizontal angle between the cable 12 and the roof slab 1, F Ny F N The vertical component of force, F1 is the weight of the weight piece 8, L1 is the distance between F1 and the edge support point of the roof floor 1, and L2 is F Ny The distance between the line of action and the edge support point of the roof slab 1, G1 is the deadweight of the cantilevered eaves 161 above the roof slab, F2 is the deadweight of the formwork frame erected for the cantilevered eaves 161 above the construction roof slab, L3 is the distance between the point of action of the combined force of G1 and F2 and the edge support point of the roof slab 1, G2 is the deadweight of the cantilevered eaves 162 of the cantilevered part, F3 is the deadweight of the formwork frame erected for the cantilevered eaves 162 of the construction cantilevered part, L4 is the distance between the point of action of the combined force of G2 and F3 and the edge support point of the roof slab 1, wherein, when calculating the first anti-overturning system, the effect of the weight member 8 is not considered, and when calculating the second anti-overturning system, the effect of the cable 12 is not considered.

[0069] When the effect of the cable is not considered,

[0070]

[0071] The gravity F1 of the ballast 8 must satisfy:

[0072]

[0073] When the effect of the weight 8 is not considered,

[0074]

[0075] Tension F of cable 12 N Need to meet:

[0076]

[0077] Through such a design, two redundant anti-overturning systems, namely the ballast 8 and the cable 12, are provided, and the anti-overturning safety factor is ≮2, so that a good aerial support mode can be achieved.

[0078] In one embodiment of the present invention, a sensor is embedded in the cable or under the weight to monitor stress changes in real time. When the force value of the cable or the weight deviates from the design value by 10%, an automatic warning is issued. For example, a fiber optic sensor can be embedded in the cable.

[0079] In one embodiment of the present invention, in step 2, the eaves columns 4 are arranged in the edge area 17 and along the upward extension line of the outer wall of the high-rise building.

[0080] Through such a design, the eaves columns are arranged vertically along the extension line of the exterior wall, so that the vertical load of the cantilevered eaves can be transferred to the main structure (such as shear walls or frame columns) through the shortest path.

[0081] In one embodiment of the present invention, referring to Figures 1 to 5 The specifications of the steel section 7 are determined based on the deadweight G2 of the cantilevered eaves 162 and the deadweight F3 of the formwork, specifically meeting the following requirements:

[0082] Design value F of the bearing capacity of a single steel section 7 y Need to meet:

[0083]

[0084] Among them, S is the spacing of the steel sections, and n is the number of steel sections;

[0085] Section bending modulus W of steel y Need to meet:

[0086]

[0087] Where f is the design value of the steel section’s bending strength.

[0088] In one embodiment of the present invention, referring to Figures 1 to 5The steel section 7 is made of hot-rolled H-shaped steel, the spacing S of the steel section is 0.8~1.5m, the cross-sectional height H is 200~400mm, and the length of the steel section 7 extending out of the first side 14 of the roof floor 1 does not exceed 2 / 3 of the total length of the steel section 7.

[0089] In one embodiment of the present invention, referring to Figures 1 to 5 The burial depth and specifications of the first anchor ring 13 and the second anchor ring 13' are determined by the tension F of the cable 12. N Confirm, specifically meet:

[0090] Anchorage length L of anchor ring a Need to meet:

[0091]

[0092] Where d is the diameter of the steel bars of the first and second anchor rings, and τb is the bond strength between concrete and steel bars;

[0093] Anchor ring steel cross-sectional area A s Need to meet:

[0094]

[0095] Among them, f y is the design value of steel bar tensile strength.

[0096] In one embodiment of the present invention, referring to Figures 1 to 5 The first anchor ring 13 and the second anchor ring 13' are made of HRB400 grade steel bars with a diameter of not less than 20 mm and a buried depth of not less than 30 times the diameter of the steel bars. A 180° hook is provided at the end of the anchor ring.

[0097] In one embodiment of the present invention, referring to Figures 1 to 5 The cable 12 is made of steel strand or high-strength steel wire bundle, and its breaking strength standard value is F pk Need to meet:

[0098]

[0099] The connection between the cable and the anchor ring adopts hot cast anchor or cold extruded anchor.

[0100] Example 2

[0101] This embodiment provides a construction system for a cantilevered eave of a high-rise building. The construction system includes a high-rise building and a roof slab 1 disposed on the top of the high-rise building. The roof slab 1 includes a first side 14 and a second side 15 opposite to the first side 14. A cantilevered eave 16 is provided in an area above the first side 14. The cantilevered eave 16 includes a cantilevered eave 161 above the roof slab and a cantilevered eave 162 at the cantilevered portion. A roof beam 2 is provided on the second side 15. The length direction of the roof beam 2 and the cantilevered eave 16 is parallel to the X-axis direction.

[0102] Reference Figure 1 and Figure 2 A first anchor ring 13 is embedded in the top of the roof beam 2, and a plurality of parallel section steels 7 are arranged along the X-axis direction on the upper surface of the first side 14 of the roof slab 1. The length direction of the section steel 7 is consistent with the Y-axis direction. A portion of the section steel 7 is arranged on the first side 14 of the roof slab 1, and another portion of the section steel 7 extends out of the first side 14 of the roof slab.

[0103] Reference Figure 1 and 2 In the overlapping area between the steel section 7 and the roof slab 1, the portion of the steel section 7 close to the edge of the roof slab 1 is an edge area 17, and the remaining portion is an inner area 18. A cantilevered eave 161 above the roof slab is provided above the edge area 17. The cantilevered eave 161 above the roof slab includes a vertically supported eave column 4, a portion of the eave slab 5, and an eave beam 6. The portion of the eave slab 5 is provided above the eave column 4 and is arranged in an inclined manner gradually decreasing from the inside to the outside of the high-rise building. The eave beam 6 is provided at a height lower than the eave slab 5 and its length direction is arranged along the X-axis. A second anchor ring 13' is provided at the highest eave beam 6. A cable 12 is used to connect the first anchor ring 13 and the second anchor ring 13', respectively, and is tightened to a certain tension.

[0104] Reference Figure 1 and Figure 3 A cantilevered eave 162 is provided above the section steel 7 extending out of the roof slab 1. The cantilevered eave 162 includes another portion of the eaves board 5 and an eaves beam 6. The other portion of the eaves board 5 continues to extend obliquely along the eaves board 5 of the cantilevered eave 161 above the roof slab. The other portion of the eaves board 5 is provided with another portion of the eaves beam 6. The length direction of the other portion of the eaves beam 6 is arranged along the X-axis.

[0105] In one embodiment of the present invention, a ballast is placed in the inner area 18 of the section steel 7 .

[0106] In one embodiment of the present invention, the conditions that the first anti-overturning system and the second anti-overturning system need to meet, the specifications of the steel sections, and the embedding depths and specifications of the first anchor ring and the second anchor ring can refer to Example 1.

[0107] While the preferred embodiments of the present invention have been described in detail above, it should be understood that, after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention. Such equivalents also fall within the scope of the claims appended hereto.

Claims

1. A construction method for cantilevered eaves of a high-rise building, characterized in that: The top of the high-rise building includes a roof slab, the roof slab includes a first side and a second side opposite to the first side, the upper area of ​​the first side is provided with the cantilevered eaves, the cantilevered eaves include a cantilevered eave above the roof slab and a cantilevered eaves of the cantilevered portion, the second side is provided with a roof beam, the length direction of the roof beam and the cantilevered eaves is parallel to the X-axis direction, and the construction method includes the following steps: Step 1: pre-embed a first anchor ring at the top of the roof beam, arrange a plurality of parallel steel sections along the X-axis direction on the upper surface of the first side of the roof slab, wherein the length direction of the steel sections is consistent with the Y-axis direction, a portion of the steel sections is arranged on the first side of the roof slab, and another portion of the steel sections extends out of the first side of the roof slab; Step 2: In the overlapping area between the section steel and the roof slab, the portion of the section steel close to the edge of the roof slab is the edge area and the remaining portion is the inner area; a cantilevered eave above the roof slab is constructed above the edge area; the cantilevered eave above the roof slab includes a vertically supported eaves column, a portion of the eaves board and an eaves beam; a portion of the eaves board is arranged above the eaves column and is gradually lowered from the inside to the outside of the high-rise building; the eaves beam is arranged at a height of the eaves board and is arranged along the X-axis in its length direction; a second anchor ring is arranged at the highest eaves beam; a cable is used to connect the first anchor ring and the second anchor ring respectively and tighten them to a certain tension; Step 3: constructing the cantilevered eaves in the area above the steel section extending out of the roof slab, wherein the cantilevered eaves include another portion of the eaves board and another portion of the eaves beam, wherein the other portion of the eaves board continues to extend obliquely along the eaves board of the cantilevered eaves above the roof slab, and the other portion of the eaves board is provided with another portion of the eaves beam, and the length direction of the other portion of the eaves beam is arranged along the X-axis; Step 4: dismantle the formwork, protective device and the cables set up for the cantilevered eaves above the roof floor constructed in step 2, dismantle the formwork and protective device set up for the cantilevered eaves of the cantilevered part constructed in step 3, and then construct a parapet next to the eaves column.

2. The construction method of a cantilevered eave of a high-rise building according to claim 1, characterized in that: In step 2, a ballast is placed on the inner area of ​​the steel section.

3. The construction method of a cantilevered eave of a high-rise building according to claim 2, characterized in that: F N is the tension of the cable, θ is the horizontal angle between the cable and the roof slab, F Ny F N The vertical component of force, F1 is the weight of the weight, L1 is the distance between F1 and the edge support point of the roof floor, L2 is F Ny The distance between the line of action and the edge support point of the roof slab, G1 is the deadweight of the cantilevered eaves above the roof slab, F2 is the deadweight of the formwork frame erected for the construction of the cantilevered eaves above the roof slab, L3 is the distance between the point of action of the combined forces of G1 and F2 and the edge support point of the roof slab, G2 is the deadweight of the cantilevered eaves of the cantilevered part, F3 is the deadweight of the formwork frame erected for the construction of the cantilevered eaves of the cantilevered part, L4 is the distance between the point of action of the combined forces of G2 and F3 and the edge support point of the roof slab, where When the effect of the cable is not considered, ； The gravity F1 of the ballast must satisfy: ； When the effect of the ballast is not considered, ； The tension F of the cable N Need to meet: 。 4. The construction method of a cantilevered eave of a high-rise building according to claim 3, characterized in that: The specifications of the steel sections are determined based on the deadweight G2 of the cantilevered eaves and the deadweight F3 of the formwork, specifically meeting the following requirements: The design value of the bearing capacity of a single steel section is F y Need to meet: ； Wherein, S is the spacing of the steel sections, and n is the number of steel sections; Section bending modulus W of steel y Need to meet: ； Where f is the design value of the steel section’s bending strength.

5. The construction method of a cantilevered eave of a high-rise building according to claim 4, characterized in that: The steel section is hot-rolled H-shaped steel, the spacing S of the steel section is 0.8~1.5m, the cross-sectional height H is 200~400mm, and the length of the steel section extending from the first side of the roof floor does not exceed 2 / 3 of the total length of the steel section.

6. The construction method of a cantilevered eave of a high-rise building according to claim 3, characterized in that: The buried depth and specifications of the first anchor ring and the second anchor ring are determined by the cable tension F N Confirm, specifically meet: Anchorage length L of anchor ring a Need to meet: ； Wherein, d is the diameter of the steel bars of the first anchor ring and the second anchor ring, and τb is the bond strength between concrete and steel bars; Anchor ring steel cross-sectional area A s Need to meet: ； Among them, f y is the design value of steel bar tensile strength.

7. The construction method of a cantilevered eave of a high-rise building according to claim 6, characterized in that: The first anchor ring and the second anchor ring are made of HRB400 grade steel bars with a diameter of not less than 20 mm and a buried depth of not less than 30 times the diameter of the steel bars, and a 180° hook is provided at the end of the anchor ring.

8. The construction method of a cantilevered eave of a high-rise building according to claim 1, characterized in that: The cable is made of steel strand or high-strength steel wire bundle, and its breaking strength standard value F pk Need to meet: ； The connection between the cable and the anchor ring adopts hot cast anchor or cold extruded anchor.

9. A construction system for cantilevered eaves of high-rise buildings, characterized in that: The construction system includes a high-rise building and a roof slab disposed on the top of the high-rise building, wherein the roof slab includes a first side and a second side opposite to the first side, the upper area of ​​the first side is provided with the cantilevered eaves, the cantilevered eaves include a cantilevered eave above the roof slab and a cantilevered eave of a cantilevered portion, and the second side is provided with a roof beam, wherein the length direction of the roof beam and the cantilevered eaves is parallel to the X-axis direction; in A first anchor ring is embedded in the top of the roof beam, and a plurality of parallel steel sections are arranged along the X-axis direction on the upper surface of the first side of the roof slab, wherein the length direction of the steel sections is consistent with the Y-axis direction, a portion of the steel sections is arranged on the first side of the roof slab, and another portion of the steel sections extends out of the first side of the roof slab. In the overlapping area of ​​the steel section and the roof slab, the portion of the steel section close to the edge of the roof slab is the edge area and the remaining portion is the inner area. A cantilevered eaves above the roof slab is provided above the edge area. The cantilevered eaves above the roof slab include vertically supported eaves columns, part of the eaves slab and eaves beams. Part of the eaves slabs are arranged above the eaves columns and are gradually lowered from the inside to the outside of the high-rise building. The eaves beams are arranged at a height of the eaves slabs and are arranged along the X-axis in their length direction. A second anchor ring is provided at the highest eaves beam. The first anchor ring and the second anchor ring are respectively connected by cables and tightened to a certain tension. The cantilevered eaves are provided in the upper area of ​​the steel section extending out of the roof slab, and the cantilevered eaves include another part of the eaves plate and another part of the eaves beam. The other part of the eaves plate continues to extend obliquely along the part of the eaves plate that cantilevers out above the roof slab, and the other part of the eaves plate is provided with another part of the eaves beam, and the length direction of the other part of the eaves beam is arranged along the X-axis.

10. The construction system for cantilevered eaves of high-rise buildings according to claim 9, characterized in that: A ballast is placed in the inner area of ​​the steel section.

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