Construction method of super-high 50-meter floor-mounted outer scaffold

Abstract

This invention discloses a method for erecting an ultra-high 50-meter-tall ground-supported external scaffold, including the following steps: Step 1, pre-construction preparation; Step 2, scaffold foundation treatment. This invention targets ultra-high ground-supported scaffolds above 50 meters by setting up a layered double-track steel wire rope unloading system to transfer the vertical load of the upper scaffold to the main building structure, significantly reducing the vertical axial force on the lower uprights and preventing upright instability, thus solving the core problem of insufficient upright bearing capacity in ultra-high ground-supported scaffolds. The steel wire rope corners are equipped with shear protection and safety bends, ensuring a safe and reliable unloading structure. Pre-embedded rigid wall ties are used, with positioning and pre-embedding completed before concrete pouring. Compared to post-installed wall ties, this provides greater connection rigidity. The spacing of the wall ties is differentiated across layers, and some floors are equipped with anti-eddy current reverse-pull rings, significantly improving the scaffold's resistance to lateral displacement and overturning, making it suitable for typhoons and rainy, windy conditions in South China.

Description

Technical Field

[0001] This invention relates to the field of building construction scaffolding technology, specifically a method for erecting an ultra-high 50-meter-high ground-supported external scaffolding. Background Technology

[0002] Coupler-type steel pipe ground-supported scaffolding is widely used for protective operations during the construction of exterior walls of industrial plants and high-rise buildings. According to current standards, the conventional erection height limit for ordinary double-row ground-supported scaffolding is 32m. Erection heights exceeding 50m are considered to be of a relatively high risk and must undergo expert review of a special plan.

[0003] However, traditional construction using ground-based scaffolding for heights exceeding 50m has the following drawbacks: (1) The total height of the frame is large and the vertical axial force of the uprights is huge. If the uprights are relied on to transfer all the vertical loads, the uprights are prone to buckling and the risk of the overall frame collapse is high. Conventional construction lacks reasonable layered unloading technology. The construction of unloading rings and wire ropes is not standardized. Shear protection is lacking and the wire ropes are prone to wear and breakage. (2) The wall ties are rear-mounted, which is not stiff enough. The pre-embedded positioning is inaccurate. After the concrete is poured, the wall ties fail to connect. The frame is not strong enough to resist lateral displacement and overturning. In typhoon and rainy areas, the horizontal wind load is large, and the frame is very easy to deform laterally. (3) The construction lacks dynamic monitoring methods throughout the entire process and relies solely on manual visual inspection. The axial force of the uprights and the displacement of the frame cannot be quantified, and the risk discovery is delayed. There is a lack of phased acceptance inspection and the graded control of hazardous sources has not been implemented. (4) The dismantling process of ultra-high scaffolding is extremely risky. On site, there are often instances of premature removal of wall ties and unloading components, cross-operation between upper and lower levels, and throwing of materials from high altitudes, which can easily lead to falls from heights and scaffolding collapse accidents. (5) When scaffolding is erected on the basement top slab or roof floor, without verifying the load-bearing capacity of the floor slab and setting back supports, it is easy to cause floor slab cracking and collapse accidents. Summary of the Invention

[0004] The purpose of this invention is to provide a method for erecting a 50-meter-high ground-supported external scaffolding, addressing the following issues in the background: the scaffolding has a large total height, resulting in enormous vertical axial forces on the uprights. If the entire vertical load is transferred solely by the uprights, the uprights are prone to buckling and instability, leading to a high risk of overall scaffolding collapse. Other issues include: conventional construction methods lacking proper layered unloading techniques; non-standard construction of unloading rings and wire ropes; lack of shear protection; and wire ropes being prone to wear and breakage. Furthermore, the use of post-installed wall ties results in insufficient rigidity. Inaccurate pre-embedded positioning leads to displacement after concrete pouring, causing wall tie failure and insufficient resistance to lateral displacement and overturning. This method is also applicable in typhoon-prone and rainy areas. The horizontal wind load is large, making the scaffolding extremely prone to lateral deformation; the construction process lacks dynamic monitoring methods throughout, relying solely on manual visual inspection, making it impossible to quantify the axial force of the uprights and the displacement of the scaffolding, resulting in delayed risk detection; there is a lack of phased acceptance inspections and the failure to implement graded control of hazard sources; the dismantling process of ultra-high scaffolding is extremely risky, with frequent instances of premature removal of wall ties and unloading components, overlapping operations at different levels, and materials being thrown from heights, which greatly increases the risk of falls from heights and scaffolding collapses; when scaffolding is erected on basement slabs or roof slabs, the lack of calculation of the slab's load-bearing capacity and the installation of back support can easily lead to slab cracking and collapse accidents.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for erecting a 50-meter-high ground-supported external scaffold, comprising the following steps: Step 1: Pre-construction preparation: Complete the preparation, calculation and verification of the special plan and expert review; conduct on-site inspection of incoming steel pipes, fasteners, scaffold boards, unloading wire ropes and embedded lifting rings; conduct safety technical briefings for workers. Step 2, Scaffolding foundation treatment: Treat the outdoor ground or basement roof foundation. For outdoor foundations, compact and harden with C20 plain concrete. For basement roof slabs, use C30 concrete slabs. Set temporary back support under the roof slab at the position corresponding to the uprights. Set drainage ditches and sump drainage structures for the foundation. Set bases and wooden pads with a length of not less than two spans at the bottom of the uprights. Step 3: Erect the scaffold layer by layer: Use φ48.3×3.6mm steel pipes to erect double-row ground scaffolding, with a longitudinal spacing of 1.5m, a transverse spacing of 0.8m, and a step distance of 2.0m; the uprights are connected by butt couplers, and the joints of adjacent uprights are staggered; erect longitudinal horizontal bars, transverse horizontal bars, and ground-level bars simultaneously; and install continuous scissor bracing on the outer side at full height as the erection progresses. Step 4: Construction of pre-embedded rigid wall ties: Pre-embed wall ties before pouring the main structure; in areas with a floor height ≤ 4m, use 2 spans per ties, and in areas with a floor height > 4m, use 3 spans per ties; the wall ties are set close to the main nodes, and the distance from the main nodes is no more than 300mm. Rigid ties are used, and anti-eddy current reverse tension structures are set up at the same time. Step 5: Layered steel wire rope unloading installation: Erect the scaffold to the preset unloading elevation, utilize the pre-embedded φ20 steel rebar lifting rings in the structure, and install φ14 steel wire rope unloading components; set up two unloading levels for the 55.5m total height ground scaffold, with the first unloading elevation at 16.00m and the second unloading elevation at 31.25m; hook the steel wire ropes to the main nodes of the scaffold body, set rope clamps and safety bends, and install anti-shear protection pads at the contact points between the steel wire ropes and the lifting rings; Step Six: Construction of Scaffold Protection and Enclosure: Lay scaffold boards on the working level and install guardrails and toe boards; fully hang dense safety netting on the exterior facade of the scaffold, and install horizontal safety netting at intervals below the working level; set up personnel access channels, protective sheds, and lightning protection grounding structures; Step 7: Full-process monitoring and control: The entire erection process is monitored using total stations and stress sensors. Monitoring items include the verticality of the scaffold, the horizontal displacement of the scaffold, and the axial force of the uprights. Warning thresholds are set, and work is stopped immediately when the warning value is reached. The frequency of re-measurement is increased before and after typhoons and rainstorms. Step 8: Risk Classification and Control during Use: Implement risk classification and control of scaffolding hazards, regularly check the torque of fasteners, wall ties, unloading wire ropes, and the integrity of components; implement the sign-raising acceptance system, and prohibit the use of scaffolding that has not passed the acceptance. Step Nine, Standardized Dismantling by Grade: Dismantling follows the principles of top-down, dismantling after erection, and dismantling the last erected first, and setting up a warning and isolation zone; first dismantle the protective facilities, and then dismantle the poles layer by layer; unloading wire ropes and wall ties are dismantled layer by layer simultaneously with the scaffolding, and it is strictly forbidden to dismantle wall ties and unloading components in advance; components and materials are passed by tools, and throwing from heights is prohibited.

[0006] As a further technical solution of the present invention, when the scaffolding is placed on the basement roof in step two, the roof is 250mm thick, made of C30 concrete, and reinforced with double-layer Φ10@150 reinforcement; the axial force of the uprights is verified, and the safety factor is not less than 1.10; temporary steel pipe back support is erected at the corresponding upright positions under the roof.

[0007] As a further technical solution of the present invention, in step three, all the pole extensions except for the top step of the top layer use butt couplers and overlapping is strictly prohibited; the scissor bracing is continuously laid out along the entire height of the outer side of the frame, the width of each scissor bracing is ≥4 spans and ≥6m, the angle between the diagonal bar and the ground is 45°-60°, the overlap length of the scissor bracing diagonal bar extension is ≥1000mm, and it is fixed with no less than 2 swivel couplers.

[0008] As a further technical solution of the present invention, in step five, the unloading wire rope is a 6×19 structure φ14 wire rope, the lifting ring is pre-embedded with HPB300Φ20 steel bars, and the pre-embedded anchorage depth is ≥35d; the number of rope clamps is not less than 3, the spacing between rope clamps is 6-8 times the diameter of the wire rope, a safety bend is set at the end of the rope, and rubber anti-shear pads are set at the corner of the wire rope.

[0009] As a further technical solution of the present invention, the pre-embedded wall ties in step four are positioned and fixed during the formwork erection stage, and form a rigid connection after the concrete is poured; for floors with a floor height greater than 4m, the wall ties are arranged in 3 spans; for floors with a floor height not greater than 4m, they are arranged in 2 spans, and some floors are equipped with a 5-span anti-eddy current reverse pull ring structure.

[0010] As a further technical solution of the present invention, the monitoring in step seven is specifically as follows: during the erection stage, monitoring is carried out once every two steps after the erection is completed; during the use stage, monitoring is carried out once every 7 days under normal circumstances; re-measurement must be carried out before and after heavy rain and typhoon; the allowable deviation of the verticality of the frame is 1 / 200 of the total height of the frame, and the maximum deviation is no more than 100mm.

[0011] As a further technical solution of the present invention, the acceptance inspection in step eight specifically involves conducting segmented acceptance inspections after the scaffolding is erected in sections. The inspection documents include component information, calculation sheets, erection records, and monitoring records. If the inspection fails, construction work is strictly prohibited.

[0012] As a further technical solution of the present invention, the dismantling operation in step nine specifically includes: simultaneously dismantling operations at different levels are strictly prohibited; wall ties and unloading components must be dismantled layer by layer along with the frame, and large-scale dismantling of wall ties in advance is prohibited; dismantling operations must be stopped immediately in case of strong winds or heavy rain.

[0013] As a further technical solution of the present invention, the formula for calculating the stability of the upright in step two is as follows:

[0014] In the formula, N is the design value of the axial force of the upright, in kN. Let A be the stability coefficient of the axially compressed member, and A be the cross-sectional area of ​​the steel pipe upright (in mm²). 2 f is the design value of the compressive strength of the steel pipe, in N / mm². 2 The formula for calculating the strength of the unloading wire rope in step one is as follows:

[0015] In the formula, T is the design value of the maximum tensile force that the wire rope can withstand, in kN, and F. g The total breaking strength of the wire rope is kN, and K is the safety factor of the wire rope. For unloading, K≥8. The formula for calculating the design value of the axial force of the wall tie in step four is as follows:

[0016] In the formula, N lw The axial force generated by the wall ties constraining the out-of-plane deformation of the scaffold; N wThe axial force on the wall ties under wind load is given. The formula for calculating the standard value of the scaffolding wind load in step two is as follows:

[0017] In the formula, w k The standard value of wind load is kN / m. 2 μ s For scaffolding wind load shape coefficient; μ z is the wind pressure height variation coefficient; w0 is the basic wind pressure, taken as 0.55 kN / m. 2 .

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. For ultra-high ground-supported scaffolding over 50m, a layered double-track steel wire rope unloading system is installed to transfer the vertical load of the upper scaffolding to the main building structure, significantly reducing the vertical axial force of the lower uprights, preventing upright instability, and solving the core problem of insufficient upright load-bearing capacity of ultra-high ground-supported scaffolding; the steel wire rope corners are equipped with anti-shear protection and safety bends, making the unloading structure safe and reliable. 2. Pre-embedded rigid wall ties are used, and the positioning and pre-embedding are completed before concrete pouring. Compared with post-installed wall ties, the connection rigidity is greater. The spacing of the wall ties is set differently for each floor. Some floors are equipped with anti-eddy current reverse pull rings, which significantly improves the frame's resistance to lateral displacement and overturning, and is suitable for typhoon, rainy and windy conditions in South China. 3. Differentiate between outdoor ground and basement roof slab foundations. Perform load-bearing capacity calculations on the roof slab and install back support to prevent cracking and damage to the floor slab due to the pressure of the uprights. Provide drainage ditches and sump pits for the foundation to prevent waterlogging and settlement. 4. Implement full-process quantitative monitoring, including scaffold verticality, horizontal displacement, and pole axial force, set early warning thresholds, and conduct tiered monitoring during erection, use, and before and after typhoons and rainstorms, replacing traditional manual visual inspection with quantitative data monitoring to provide early warning of risks; implement segmented sign-based acceptance and tiered control of hazardous sources to achieve closed-loop management; 5. The dismantling process must be strictly carried out from top to bottom. Wall ties and unloading components must be dismantled layer by layer along with the scaffolding. Premature dismantling is strictly prohibited. Warning and isolation measures must be set up, and throwing materials from heights is prohibited to avoid major safety risks of collapse and falls from heights during the dismantling of ultra-high scaffolding. 6. The entire construction method fully complies with the expert demonstration requirements for major and hazardous projects. The procedures are complete, and 50-56m double-row coupler-type ground scaffolding is directly applied. It can be used for both new factory buildings and high-rise building exterior wall construction, and has strong versatility. Attached Figure Description

[0019] Figure 1 This is a flowchart of the present invention; Figure 2 This is a perspective view of the embedded part of the wall connection component of the present invention; Figure 3 This is a side view of the fastener of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1-3 This invention provides a method for erecting a 50-meter-high ground-supported external scaffold, comprising the following steps: Step 1: Pre-construction preparation: Complete the preparation, calculation and verification of the special plan and expert review; conduct on-site inspection of incoming steel pipes, fasteners, scaffold boards, unloading wire ropes and embedded lifting rings; conduct safety technical briefings for workers. Step 2, Scaffolding foundation treatment: Treat the outdoor ground or basement roof foundation. For outdoor foundations, compact and harden with C20 plain concrete. For basement roof slabs, use C30 concrete slabs. Set temporary back support under the roof slab at the position corresponding to the uprights. Set drainage ditches and sump drainage structures for the foundation. Set bases and wooden pads with a length of not less than two spans at the bottom of the uprights. Step 3: Erect the scaffold layer by layer: Use φ48.3×3.6mm steel pipes to erect double-row ground scaffolding, with a longitudinal spacing of 1.5m, a transverse spacing of 0.8m, and a step distance of 2.0m; the uprights are connected by butt couplers, and the joints of adjacent uprights are staggered; erect longitudinal horizontal bars, transverse horizontal bars, and ground-level bars simultaneously; and install continuous scissor bracing on the outer side at full height as the erection progresses. Step 4: Construction of pre-embedded rigid wall ties: Pre-embed wall ties before pouring the main structure; in areas with a floor height ≤ 4m, use 2 spans per ties, and in areas with a floor height > 4m, use 3 spans per ties; the wall ties are set close to the main nodes, and the distance from the main nodes is no more than 300mm. Rigid ties are used, and anti-eddy current reverse tension structures are set up at the same time. Step 5: Layered steel wire rope unloading installation: Erect the scaffold to the preset unloading elevation, utilize the pre-embedded φ20 steel rebar lifting rings in the structure, and install φ14 steel wire rope unloading components; set up two unloading levels for the 55.5m total height ground scaffold, with the first unloading elevation at 16.00m and the second unloading elevation at 31.25m; hook the steel wire ropes to the main nodes of the scaffold body, set rope clamps and safety bends, and install anti-shear protection pads at the contact points between the steel wire ropes and the lifting rings; Step Six: Construction of Scaffold Protection and Enclosure: Lay scaffold boards on the working level and install guardrails and toe boards; fully hang dense safety netting on the exterior facade of the scaffold, and install horizontal safety netting at intervals below the working level; set up personnel access channels, protective sheds, and lightning protection grounding structures; Step 7: Full-process monitoring and control: The entire erection process is monitored using total stations and stress sensors. Monitoring items include the verticality of the scaffold, the horizontal displacement of the scaffold, and the axial force of the uprights. Warning thresholds are set, and work is stopped immediately when the warning value is reached. The frequency of re-measurement is increased before and after typhoons and rainstorms. Step 8: Risk Classification and Control during Use: Implement risk classification and control of scaffolding hazards, regularly check the torque of fasteners, wall ties, unloading wire ropes, and the integrity of components; implement the sign-raising acceptance system, and prohibit the use of scaffolding that has not passed the acceptance. Step Nine, Standardized Dismantling by Grade: Dismantling follows the principles of top-down, dismantling after erection, and dismantling the last erected first, and setting up a warning and isolation zone; first dismantle the protective facilities, and then dismantle the poles layer by layer; unloading wire ropes and wall ties are dismantled layer by layer simultaneously with the scaffolding, and it is strictly forbidden to dismantle wall ties and unloading components in advance; components and materials are passed by tools, and throwing from heights is prohibited.

[0022] As a further technical solution of the present invention, in step two, when the scaffolding is placed on the top slab of the basement, the top slab is 250mm thick, made of C30 concrete, and reinforced with double-layer Φ10@150 reinforcement in both directions; the axial force of the uprights is verified, and the safety factor is not less than 1.10; temporary steel pipe back support is erected at the corresponding upright positions under the top slab.

[0023] As a further technical solution of the present invention, in step three, all the pole extensions except the top step of the top layer use butt couplers and overlapping is strictly prohibited; the scissor bracing is continuously laid out along the entire height of the outer side of the frame, each scissor bracing is ≥4 spans wide and ≥6m wide, the angle between the diagonal brace and the ground is 45°-60°, the overlapping length of the scissor bracing diagonal brace extension is ≥1000mm, and it is fixed with no less than 2 swivel couplers.

[0024] As a further technical solution of the present invention, in step five, the unloading wire rope is a 6×19 structure φ14 wire rope, the lifting ring is pre-embedded with HPB300Φ20 steel bars, and the pre-embedded anchorage depth is ≥35d; the number of rope clamps is not less than 3, the spacing between rope clamps is 6-8 times the diameter of the wire rope, a safety bend is set at the end of the rope, and rubber anti-shear pads are set at the corner of the wire rope.

[0025] As a further technical solution of the present invention, the pre-embedded wall tie in step four is positioned and fixed during the formwork erection stage, and a rigid connection is formed after the concrete is poured; for floors with a floor height greater than 4m, the wall tie is arranged in 3 spans; for floors with a floor height not greater than 4m, it is arranged in 2 spans, and some floors are equipped with a 5-span anti-eddy current reverse pull ring structure.

[0026] As a further technical solution of the present invention, the monitoring in step seven is specifically as follows: during the erection stage, monitoring is carried out once every two steps after the erection is completed; during the use stage, monitoring is carried out once every 7 days under normal circumstances; re-measurement must be carried out before and after heavy rain and typhoon; the allowable deviation of the verticality of the frame is 1 / 200 of the total height of the frame, and the maximum deviation is no more than 100mm.

[0027] As a further technical solution of the present invention, the acceptance inspection in step eight specifically involves conducting segmented acceptance inspections after the scaffolding is erected in sections. The inspection documents include component information, calculation sheets, erection records, and monitoring records. If the inspection fails, construction work is strictly prohibited.

[0028] As a further technical solution of the present invention, the dismantling operation in step nine specifically includes: simultaneously dismantling operations at different levels are strictly prohibited; wall ties and unloading components must be dismantled layer by layer along with the frame, and large-scale dismantling of wall ties in advance is prohibited; dismantling operations must be stopped immediately in case of strong winds or heavy rain.

[0029] As a further technical solution of the present invention, the formula for calculating the stability of the upright in step two is as follows:

[0030] In the formula, N is the design value of the axial force of the upright, in kN. Let A be the stability coefficient of the axially compressed member, and A be the cross-sectional area of ​​the steel pipe upright (in mm²). 2 f is the design value of the compressive strength of the steel pipe, in N / mm². 2 The formula for calculating the strength of the unloading wire rope in step one is as follows:

[0031] In the formula, T is the design value of the maximum tensile force that the wire rope can withstand, in kN, and F. g The total breaking strength of the wire rope is kN, and K is the safety factor of the wire rope. For unloading, K≥8. The calculation formula for the design value of the axial force of the wall tie in step four is as follows:

[0032] In the formula, N lw The axial force generated by the wall ties constraining the out-of-plane deformation of the scaffold; N w The axial force on the wall ties under wind load is given. The formula for calculating the standard value of the scaffolding wind load in step two is as follows:

[0033] In the formula, w k The standard value of wind load is kN / m. 2 μ s For scaffolding wind load shape coefficient; μ zis the wind pressure height variation coefficient; w0 is the basic wind pressure, taken as 0.55 kN / m. 2 .

[0034] In this invention, the method was applied to Buildings 2 and 3 of the Longda Digital Technology Cloud Corridor Factory Project. The maximum erection height of the double-row, ground-supported scaffolding was 55.50m, which is considered a large-scale, hazardous project. After expert review and approval of the specific plan, the construction method of this invention was implemented. In the early stages of construction, a special construction plan for ultra-high ground-supported scaffolding was prepared, and multi-condition calculations of the load-bearing capacity of the scaffolding and top slab were completed and expert review was organized. φ48.3×3.6mm steel pipes were used for the incoming steel pipes, and steel pipes, fasteners, and wire ropes underwent retesting upon arrival. Specialized scaffolders were required to hold valid certificates and safety technical briefings were conducted for all personnel. Scaffolding foundation treatment: Part of the scaffolding is placed on the outdoor ground, where the original soil is compacted and then a 100mm thick layer of C20 plain concrete is poured for hardening; the other part of the scaffolding is placed on the basement roof slab, which is made of 250mm thick C30 concrete with double-layer, bidirectional Φ10@150 reinforcement; the design value of the axial force of the uprights is 10.15kN, and the safety factor is 1.10; steel pipe back support is erected under the floor slab directly below the uprights; a 3% drainage slope is set around the foundation, with supporting drainage ditches and sump pits; a base is placed at the bottom of the uprights, and a 50mm thick wooden pad is laid under the base, with the pad length not less than two spans; The scaffolding is erected in stages and layers: the vertical spacing of the uprights is 1.5m, the horizontal spacing is 0.8m, and the step distance is 2.0m; all uprights use butt couplers, and the joints of adjacent uprights are staggered by more than 500mm; ground-level bracing, longitudinal horizontal bars, and transverse horizontal bars are erected simultaneously; as the scaffolding rises, scissor bracing is continuously installed on the outer facade, with a width of not less than 4 spans, an inclination angle of 45-60°, an overlap length of ≥1000mm, and no less than 2 swivel couplers for fixing; the verticality of the uprights is corrected every 2 steps of scaffolding erected. Construction of pre-embedded rigid wall ties: During the formwork erection stage, the pre-embedded wall ties are positioned and fixed inside the formwork; after the concrete is poured and formed, rigid wall ties are formed; for floors 1-3 with a floor height ≤ 4m, 2 spans per tie are implemented; for floors 4 and above with a floor height greater than 4m, 3 spans per tie are implemented; the wall ties should be as close as possible to the main nodes, with a distance from the main nodes not exceeding 300mm; some floors are equipped with anti-eddy current reverse pull rings installed in 5 spans per tie. Layered wire rope unloading installation: The first unloading layer is installed when the scaffold is erected to an elevation of 16.00m; the second unloading layer is installed when the scaffold is erected to an elevation of 31.25m; the pre-embedded lifting rings use Φ20HPB300 steel bars with an anchoring depth ≥35d; the unloading layer uses φ14, 6×19 wire rope, and the wire rope is wrapped around the main nodes of the scaffold; rubber anti-shear pads are added at the corners of the lifting rings; no less than 3 rope clamps are used, with a spacing of 7 times the diameter of the wire rope, and a safety bend is reserved at the end of the rope; Scaffolding protection and enclosure construction: The working level is fully covered with scaffold boards, and the working level is equipped with two guardrails of 1.2m and 0.6m, as well as 180mm high toe boards; the exterior facade is fully covered with dense safety netting; a horizontal safety net is installed every 10m; dedicated pedestrian access channels and protective canopies at entrances and exits are set up; the entire scaffolding is equipped with lightning protection grounding; Full-process monitoring: After every two steps of erection, use a total station to measure the verticality and horizontal displacement of the frame; install stress sensors at key points of the uprights to collect the axial force of the uprights; verticality warning threshold: 1 / 200 of the total height, with a maximum of 100mm; if the warning threshold is reached, work must be stopped immediately for investigation and rectification; during normal use, monitoring must be carried out once every 7 days; re-measurement is required before typhoons and after heavy rains; Risk classification and control during the usage phase: Establish a classification and control list of scaffolding hazards, distinguishing between enterprise-level, project department-level, and work team-level control; regularly conduct spot checks on the tightening torque of fasteners (40-65 N·m) and check the condition of wall ties and unloading wire ropes; after each section of scaffolding is erected, implement a sign-raising acceptance system; work on the scaffolding is prohibited if the sign is not posted after acceptance. Tiered and standardized dismantling operations: Before dismantling, a hard-lined warning and isolation zone shall be set up to prohibit unauthorized personnel from entering; dismantling shall be carried out strictly from top to bottom, with erection preceded by dismantling; safety nets and guardrails shall be removed first, followed by dismantling of the structural members layer by layer; unloading wire ropes and wall ties shall be removed layer by layer simultaneously with the scaffolding, and it is strictly forbidden to cut wire ropes or remove wall ties in advance; all structural members shall be passed down using rope tools, and throwing from heights is strictly prohibited; dismantling operations shall be stopped immediately in the event of winds of level 6 or above or heavy rain.

[0035] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for erecting an ultra-high 50-meter-high ground-supported external scaffold, characterized in that, Includes the following steps: Step 1: Pre-construction preparation: Complete the preparation, calculation and verification of the special plan and expert review; conduct on-site inspection of incoming steel pipes, fasteners, scaffold boards, unloading wire ropes and embedded lifting rings; conduct safety technical briefings for workers. Step 2, Scaffolding foundation treatment: Treat the outdoor ground or basement roof foundation. For outdoor foundations, compact and harden with C20 plain concrete. For basement roof slabs, use C30 concrete slabs. Set temporary back support under the roof slab at the position corresponding to the uprights. Set drainage ditches and sump drainage structures for the foundation. Set bases and wooden pads with a length of not less than two spans at the bottom of the uprights. Step 3: Erect the scaffold layer by layer: Use φ48.3×3.6mm steel pipes to erect double-row ground scaffolding, with a longitudinal spacing of 1.5m, a transverse spacing of 0.8m, and a step distance of 2.0m; the uprights are connected by butt couplers, and the joints of adjacent uprights are staggered; erect longitudinal horizontal bars, transverse horizontal bars, and ground-level bars simultaneously; and install continuous scissor bracing on the outer side at full height as the erection progresses. Step 4: Construction of pre-embedded rigid wall ties: Pre-embed wall ties before pouring the main structure; in areas with a floor height ≤ 4m, use 2 spans per ties, and in areas with a floor height > 4m, use 3 spans per ties; the wall ties are set close to the main nodes, and the distance from the main nodes is no more than 300mm. Rigid ties are used, and anti-eddy current reverse tension structures are set up at the same time. Step 5: Layered steel wire rope unloading installation: Erect the structure to the preset unloading elevation, and use the pre-embedded φ20 steel bar lifting rings to install the φ14 steel wire rope unloading assembly; The 55.5m high ground scaffolding is set up with two unloading levels. The first unloading level is at an elevation of 16.00m and the second unloading level is at an elevation of 31.25m. The main nodes of the scaffolding are secured with wire ropes, and rope clamps and safety bends are installed. Shear protection pads are installed at the contact points between the wire ropes and the lifting rings. Step Six: Construction of Scaffold Protection and Enclosure: Lay scaffold boards on the working level and install guardrails and toe boards; fully hang dense safety netting on the exterior facade of the scaffold, and install horizontal safety netting at intervals below the working level; set up personnel access channels, protective sheds, and lightning protection grounding structures; Step 7: Full-process monitoring and control: The entire erection process is monitored using a total station and stress sensors. The monitoring items include the verticality of the frame, the horizontal displacement of the frame, and the axial force of the uprights. Set early warning thresholds; if the warning value is reached, work must be stopped immediately. Increase the frequency of retesting before and after typhoons and rainstorms; Step 8: Risk Classification and Control during Use: Implement risk classification and control of scaffolding hazards, regularly check the torque of fasteners, wall ties, unloading wire ropes, and the integrity of components; implement the sign-raising acceptance system, and prohibit the use of scaffolding that has not passed the acceptance. Step Nine, Standardized Dismantling by Grade: Dismantling follows the principles of top-down, dismantling after erection, and dismantling the last erected first, and setting up a warning and isolation zone; first dismantle the protective facilities, and then dismantle the poles layer by layer; unloading wire ropes and wall ties are dismantled layer by layer simultaneously with the scaffolding, and it is strictly forbidden to dismantle wall ties and unloading components in advance; components and materials are passed by tools, and throwing from heights is prohibited.

2. The method for erecting a 50-meter-high ground-supported external scaffolding according to claim 1, characterized in that: In step two, when the scaffolding is placed on the basement roof slab, the roof slab is 250mm thick, made of C30 concrete, and reinforced with double-layer Φ10@150 reinforcement in both directions; the axial force of the uprights is verified, and the safety factor is not less than 1.10; temporary steel pipe back support is erected at the corresponding upright positions under the roof slab.

3. The method for erecting a 50-meter-high ground-supported external scaffolding according to claim 1, characterized in that: In step three, all pole extensions except for the top step of the top layer use butt couplers, and overlapping is strictly prohibited; scissor bracing is continuously installed along the entire height of the outer side of the frame, with each scissor bracing having a width of ≥4 spans and ≥6m, the angle between the diagonal brace and the ground being 45°-60°, and the overlap length of the scissor bracing diagonal brace extension being ≥1000mm, and fixed with no less than 2 swivel couplers.

4. The method for erecting a 50-meter-high ground-supported external scaffolding according to claim 1, characterized in that: In step five, the unloading wire rope is a 6×19 structure φ14 wire rope, the lifting ring is pre-embedded with HPB300Φ20 steel bars, and the pre-embedded anchorage depth is ≥35d; the number of rope clamps is not less than 3, the spacing between rope clamps is 6-8 times the diameter of the wire rope, a safety bend is set at the end of the rope, and rubber anti-shear pads are set at the corners of the wire rope.

5. The method for erecting a 50-meter-high ground-supported external scaffolding according to claim 1, characterized in that: In step four, the pre-embedded wall ties are positioned and fixed during the formwork erection stage, and a rigid connection is formed after the concrete is poured. For floors with a height greater than 4m, the wall ties are arranged in 3-span configurations; for floors with a height not greater than 4m, they are arranged in 2-span configurations. Some floors are equipped with anti-eddy current reverse pull ring structures in 5-span configurations.

6. The method for erecting a 50-meter-high ground-supported external scaffold according to claim 1, characterized in that: The monitoring and control in step seven are as follows: during the erection stage, monitoring is carried out once every two steps after erection is completed; during the use stage, monitoring is carried out once every 7 days under normal circumstances; re-measurement must be carried out before and after heavy rain and typhoon; the allowable deviation of the verticality of the frame is 1 / 200 of the total height of the frame, and the maximum deviation is no more than 100mm.

7. The method for erecting a 50-meter-high ground-supported external scaffolding according to claim 1, characterized in that: The eighth step, the acceptance inspection, specifically involves conducting a segmented acceptance inspection after the scaffolding is erected in sections. The inspection documents include component information, calculation sheets, erection records, and monitoring records. If the inspection fails, construction work is strictly prohibited.

8. The method for erecting a 50-meter-high ground-supported external scaffolding according to claim 1, characterized in that: In step nine, the dismantling work specifically includes the following: simultaneous dismantling operations at different levels are strictly prohibited; wall ties and unloading components must be dismantled layer by layer along with the scaffolding, and large-scale dismantling of wall ties in advance is prohibited; dismantling operations must be stopped immediately in case of strong winds or heavy rain.

9. The method for erecting a 50-meter-high ground-supported external scaffold according to claim 1, characterized in that: The formula for calculating the stability of the upright in step two is as follows: ， In the formula, N is the design value of the axial force of the upright, in kN. Let A be the stability coefficient of the axially compressed member, and A be the cross-sectional area of ​​the steel pipe upright (in mm²). 2 f is the design value of the compressive strength of the steel pipe, in N / mm². 2 The formula for calculating the strength of the unloading wire rope in step one is as follows: ， In the formula, T is the design value of the maximum tension of the steel wire rope, kN, F g is the total breaking tension of the steel wire rope, kN, K is the safety factor of the steel wire rope, and K≥8 when unloading. The formula for calculating the axial force design value of the wall connecting piece in step four is as follows: ， In the formula, N lw is the axial force generated by the out-of-plane deformation of the wall tie restraint scaffold; and N w is the axial force of the wall tie under the action of wind load, and the formula for calculating the standard value of the scaffold wind load in step two is as follows: ， In the formula, w k The standard value of wind load is kN / m. 2 μ s For scaffold wind load shape coefficient; μ z is the wind pressure height variation coefficient; w0 is the basic wind pressure, taken as 0.55 kN / m. 2 .

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