Construction method of shared operation platform for high-altitude parking apron cantilever structure support and protection frame

Abstract

The application provides a construction method of a shared operation platform of a high-altitude apron overhanging structure support and a protection frame, which comprises the following steps: firstly, designing and simulating a cantilevered steel triangular support frame, and integrally hoisting the prefabricated frame, welding the frame with structure floor embedded parts on site, and laying monitoring points; then, erecting an inner support frame and an outer protection scaffold above the cantilevered steel triangular support frame; then, constructing the apron overhanging structure, monitoring the cantilevered steel triangular support frame as a whole, and finally, carrying out frame dismantling construction. The application adopts a lower support type cantilevered steel triangular support frame as an apron overhanging structure support platform, and erects an inner support frame and an outer protection scaffold on the platform, thereby forming a support and protection shared operation platform system, breaking through the traditional construction process of erecting a full-disk buckle support scaffold from the ground to the roof layer by layer, and temporarily connecting the inner support frame and the outer scaffold, controlling the overhanging free end of the outer scaffold stand to be less than 4m, and ensuring the safety and stability of the frame.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and in particular relates to a construction method for a shared operating platform for the support and protective frame of a cantilevered structure of an aerial helipad. Background Technology

[0002] With the acceleration of urbanization and the continuous improvement of the medical emergency system in my country, the demand for rooftop helipads on high-rise hospital buildings is increasing. As a special functional area of ​​high-rise buildings, helipads often feature large cantilever designs in certain sections, with cantilever lengths exceeding 3 meters, posing significant construction challenges and safety risks. Traditional construction methods suffer from the following problems:

[0003] (1) The full-span disc-lock scaffolding is used to erect the scaffolding layer by layer from the ground to the roof. The scaffolding erection is large in volume, the rental and labor costs are high, the construction period is long, and the large number of scaffolding erection and dismantling procedures increase the safety risks.

[0004] (2) Using the inclined tower scaffolding as the external protection system is not supported by current standards, and when the maximum cantilever structure plate reaches 4.1m, the angle between the inclined tower steel pipe and the external frame body is too large, making it impossible to properly install wall ties, which poses a significant safety hazard.

[0005] In summary, in public welfare projects such as hospitals, where construction schedules are tight and public attention is high, traditional construction methods are difficult to meet the progress requirements. Full-span modular scaffolding schemes greatly increase the project burden, while the safety risks of inclined tower scaffolding schemes are difficult to control.

[0006] How to achieve rapid and economical construction of large cantilever structures for high-altitude helipads while ensuring construction safety, and at the same time meet the requirements of integrated support and protection, is an urgent problem to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a construction method for a shared operating platform for the support and protective frame of a cantilevered high-altitude helipad structure. It employs a downward-braced cantilevered steel triangular support frame as the support platform for the cantilevered helipad structure, and simultaneously erects an inner support frame and an outer protective scaffold on the triangular support platform, forming a shared operating platform system for support and protection. This achieves integrated support and protection, breaking through the traditional construction process of erecting full-span, modular support scaffolding layer by layer from the ground to the roof. Furthermore, by connecting the inner support frame and the outer scaffolding through temporary bracing measures, the free end of the outer scaffolding uprights is controlled to be less than 4m, ensuring the safety and stability of the scaffold structure.

[0008] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0009] A construction method for a shared operating platform for the cantilever structure support and protective frame of an aerial helipad includes the following steps:

[0010] Step 1: Design and calculation of cantilevered steel triangular support frame;

[0011] Step 2: BIM modeling and construction simulation;

[0012] Step 3: Factory prefabrication and overall hoisting of the cantilevered steel triangular support frame;

[0013] Step 4: Install strain monitoring points on the cantilevered steel triangular support frame;

[0014] Step 5: Simultaneously erect the inner support frame and the outer protective scaffolding on the cantilevered steel triangular support frame to form an operating platform system that combines support and protection;

[0015] Step 6: Construction of the cantilevered structure of the helipad, including three sub-processes: steel reinforcement, formwork, and concrete work;

[0016] Step 7: Overall strain monitoring of the cantilevered steel triangular support frame;

[0017] Step 8: Dismantle the scaffold.

[0018] Furthermore, the cantilevered steel triangular support frame includes an upper chord, a lower chord, a web member, and a secondary beam. The upper and lower chords are welded to the embedded parts of the structural floor. The web member is welded between the upper and lower chords to form a triangular structure. The secondary beam is welded to the upper surface of the upper chord and is used for subsequent connection with the external protective scaffolding, the internal support frame, and the template support frame of the cantilevered structure of the helipad.

[0019] Furthermore, in step 5, the external protective scaffolding is connected to the structural floor using wall ties, and the cantilever height of the wall ties is controlled to be less than 4m. When the cantilever height of the wall ties is greater than 4m, temporary bracing and fixing measures are taken for the internal support frame and the external protective scaffolding to enhance the overall stability of the frame. After the internal and external frames are temporarily braced, the connection must be released before pouring concrete to avoid deformation of the frame during the concrete pouring process, which would affect the structural quality.

[0020] Furthermore, in step 6, the reinforcement work includes: HRB400 grade steel bars are used for the cantilever slab of the helipad; before the steel bars are tied, lines are marked on the formwork to ensure accurate spacing of the steel bars; stirrups are set on the upper layer of the cantilever slab reinforcement at a spacing of 1000mm to prevent displacement of the steel bars during concrete pouring; in the dense area of ​​the beam-column joint reinforcement, an alternating tying method is used to ensure the quality of concrete pouring; the steel bar connection adopts lap splicing, and the lap length and anchorage length are implemented according to the design requirements and specifications.

[0021] Further, in step 6, the formwork engineering includes: the cantilever slab formwork of the helipad uses 15mm thick plywood, the secondary keel uses square steel pipes with a cross-sectional size of 40×40×20mm, arranged at a spacing of 200mm, and the main keel uses square steel pipes with a cross-sectional size of 100×50×25mm; the formwork support frame uses a disc-lock type support frame, with a vertical spacing of 0.9m or 1.2m, a horizontal spacing of 1.5m, and a step spacing of 1.5m. When the span of the cast-in-place reinforced concrete slab is greater than 4m, the formwork is arched at 1 / 1000 to 3 / 1000 of the span, the cantilever length of the adjustable support extending beyond the top horizontal bar does not exceed 600mm, and the exposed length of the threaded rod does not exceed 400mm.

[0022] Furthermore, in step 6, the concrete engineering includes: the concrete strength grade of the cantilever slab of the helipad is C30, and the slump requirement is 180±20mm; a concrete placing boom is used for pouring, and the pouring of the cantilever slab proceeds continuously from the outside to the inside. When the reinforcement at the joints is dense, a small-diameter vibrator is used for vibration, and the vibrator points are increased; the loose thickness of the concrete in the poured slab is greater than the slab thickness. After vibration, it is leveled with a screed and smoothed with a trowel, and the elevation of the slab surface is checked with a string line to strictly control the flatness; the concrete is covered and cured in a timely manner after pouring.

[0023] The present invention has the following beneficial effects:

[0024] (1) The under-braced cantilevered steel triangular support frame is used as the support platform for the cantilever structure of the apron. The load of the cantilever slab structure is borne by the steel triangular support platform. The inner support frame and the outer protective scaffolding are erected on the triangular support platform at the same time, forming a shared operating platform system for support and protection. This achieves the integration of support and protection, breaking through the traditional construction process of erecting full-span disc buckle support scaffolding from the ground to the roof layer by layer.

[0025] (2) The cantilevered steel triangular support frame was modeled and calculated using the Midas finite element software. The web-type cantilevered steel triangular support frame with H194×150×6×9 cross-section was determined to be the best choice. The maximum stress ratio of the members was 0.39, and the maximum deformation was 6mm, which is less than the design limit of F / 400=9.5mm, ensuring structural safety and reliability. Through cross-section comparison, the H-section had a lower maximum stress ratio (0.39 vs 0.49) and a smaller maximum deformation (6mm vs 10.7mm) compared to the rectangular cross-section (B160×6). Furthermore, stiffening plates could be welded to the side of the web, making processing easier and resulting in superior overall performance.

[0026] (3) The support frame is prefabricated in the factory and hoisted and installed as a whole, which reduces on-site high-altitude welding operations and saves construction time.

[0027] (4) The inner support frame and the outer scaffold are connected by temporary bracing measures to control the free end of the outer scaffold uprights to be less than 4m, so as to ensure the safety and stability of the scaffold. When the cantilever height of the wall tie is greater than 4m, temporary bracing and fixing measures are taken between the inner and outer scaffolds to enhance the overall stability of the scaffold.

[0028] (5) During the construction process, a strain monitoring system and a theodolite are used to monitor the deflection of the support frame and the verticality of the external frame poles in real time. The monitoring data are collected and analyzed in a timely manner. The results of the finite element calculation analysis are compared and corrections are made to ensure construction safety. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the layout of the cantilevered steel triangular support frame and the external protective scaffolding described in this invention;

[0030] Figure 2 This is a schematic cross-sectional view of the inner support frame and outer protective scaffolding erected according to the present invention;

[0031] Figure 3 for Figure 2 Detailed structural diagram of section A;

[0032] In the diagram: 1-Disc-lock support frame; 2-External protective scaffolding; 3-Embedded parts; 4-Secondary beams; 5-Upper chord; 6-Lower chord; 7-Web members; 8-Wall ties; 9-Strain monitoring points; 10-Integral cantilevered steel support frame. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0034] The construction method for the shared operating platform of the cantilever structure support and protective frame of the high-altitude helipad according to the present invention includes the following process:

[0035] Step 1: Design and calculation of cantilevered steel triangular support frame 10;

[0036] like Figure 1 , 2 As shown, a cantilevered steel triangular support frame 10 and an external protective scaffolding 2 system are designed to be erected on the cantilevered platform of the apron. The structural load of the cantilevered slab is entirely borne by the under-braced steel triangular support platform. The model is established and the calculation analysis is performed using midas finite element software. It is determined that the web-type cantilevered steel triangular support frame 10 is spliced ​​with H-beams with cross-sectional dimensions of H194×150×6×9 (representing H-beam height 194mm, flange width 150mm, web thickness 6mm, flange thickness 9mm).

[0037] Specifically, such as Figure 2 , 3As shown, the cantilevered steel triangular support frame 10 includes an upper chord 5, a lower chord 6, a web member 7, and a secondary beam 4. The upper chord 5 and the lower chord 6 are welded to the embedded parts 3 of the structural floor. The web member 7 is welded between the upper chord 5 and the lower chord 6 to form a triangular structure. The secondary beam 4 is welded to the upper surface of the upper chord 5 and is used for subsequent connection with the external protective scaffold 2, the internal support frame, and the formwork support frame.

[0038] Step 2: BIM modeling and construction simulation;

[0039] A three-dimensional model of the cantilevered steel triangular support frame 10 was created using BIM modeling to clarify the layout, height, and hoisting sequence of the steel supports. The BIM modeling was used to simulate the construction and installation process, guide on-site construction operations, and ensure the construction quality of the steel supports through segmented hoisting, assembly, and welding. The application of BIM technology effectively avoided installation conflicts and construction errors.

[0040] Step 3: Prefabrication and overall hoisting of the cantilevered steel triangular support frame in the factory;

[0041] All support frames are prefabricated in the factory, and all components are produced in a standardized manner. This not only facilitates the factory's material preparation and processing but also makes on-site construction easier and avoids installation and hoisting errors caused by construction personnel's lack of understanding of the on-site working environment. After processing and welding, the whole frame is transported to the site for hoisting and installation. The whole hoisting method replaces the high-altitude assembly method. On-site welding is only required to the embedded parts 3 of the structural floor, and the amount of welding is minimal.

[0042] Step 4: Deployment of strain monitoring points;

[0043] A strain monitoring system and marker-based deformation monitoring measurements were used to monitor the deflection changes of the cantilevered steel triangular support frame 10 in real time, ensuring that the monitoring access channels remained unobstructed; the specific layout of strain monitoring points 9 is as follows. Figure 1 As shown.

[0044] Step 5: Erect the inner support frame and the outer protective scaffolding 2, as follows: Figure 1 , 2 As shown, specifically, an inner support frame and an outer protective scaffold 2 are erected simultaneously on the cantilevered steel triangular support frame 10 to form an operating platform system that combines support and protection.

[0045] like Figure 2As shown, since the protective frame area of ​​the cantilevered steel triangular support frame 10 is only a single-story structure with no structural columns, the construction process first involves setting up inclined wall ties 8 to control the cantilever height of the wall ties 8 to be less than 4m. When the cantilever height of the wall ties 8 is greater than 4m, temporary bracing and fixing measures are taken between the inner and outer frames to enhance the overall stability of the frame. After the temporary bracing between the inner and outer frames, the connection must be released before pouring concrete to avoid deformation of the frame during concrete pouring that could affect the structural quality. The inner support frame is set as a disc-lock type support frame 1 according to the width of the cantilever slab. The uprights of the outer protective scaffold 2 are installed on the secondary beam 4 at the cantilever end of the cantilevered steel triangular support frame 10.

[0046] Step 6: Construction of the cantilevered structure of the helipad, including three sub-processes: steel reinforcement, formwork, and concrete work;

[0047] Reinforcement Engineering: HRB400 grade steel bars are used for the cantilever slab of the helipad. Before binding, the steel bars are positioned by marking lines on the formwork to ensure accurate spacing. Stirrups are installed on the upper layer of the cantilever slab reinforcement at 1000mm intervals to prevent displacement during concrete pouring. In areas with dense reinforcement at beam-column joints, a staggered binding method is used to ensure concrete pouring quality. Reinforcement connections are made using lap splices, with lap length and anchorage length strictly adhering to design requirements and specifications.

[0048] Formwork Engineering: The formwork for the cantilevered slab of the helipad uses 15mm thick plywood, secondary joists use 40×40×20mm square steel pipes @200, and main joists use 100×50×25mm square steel pipes. The formwork support frame also uses a disc-lock type support frame 1, with a longitudinal spacing of 0.9m / 1.2m, a transverse spacing of 1.5m, and a step distance of 1.5m. When the span of the cast-in-place reinforced concrete slab is greater than 4m, the formwork should be cambered at 1 / 1000~3 / 1000 of the span. The cantilever length of the adjustable support extending beyond the top horizontal bar should not exceed 600mm, and the exposed length of the threaded rod should not exceed 400mm. Figure 2 , 3 As shown, a special fixing device is installed on the secondary beam 4, and the uprights of the formwork support frame are set on the positioning and anti-slip rods to ensure stability.

[0049] Concrete Works: The concrete strength grade for the cantilever slab of the helipad is C30, with a slump requirement of 180±20mm. A concrete placing boom will be used for pouring. Pouring will proceed continuously from the outside in, ensuring the concrete is compacted. During vibration, the reinforcing bars and embedded parts must not be disturbed. When the reinforcing bars at joints are densely packed, a small-diameter vibrator will be used, with the vibrator frequency increased. The initial thickness of the poured concrete should be slightly greater than the slab thickness. After vibration, the surface should be leveled with a 2m screed and smoothed with a trowel. A string line should be used to check the slab elevation, and flatness must be strictly controlled. The concrete should be covered and cured promptly after pouring, with a curing time of no less than 14 days.

[0050] Step 7: Overall monitoring of the cantilevered steel triangular support frame 10;

[0051] After the cantilevered steel triangular support frame 10 is hoisted and installed to form an integral cantilevered support platform, a strain monitoring system is used to measure and monitor the deflection changes of the cantilevered support platform. The monitoring data is collected and analyzed in a timely manner, and the results are compared with the finite element analysis results to make corrections and ensure construction safety.

[0052] Step 8: Dismantling of scaffolding and cantilevered steel triangular support frame 10;

[0053] After the helipad pouring and curing are completed and the formwork support frame is dismantled, the scaffolding and cantilevered steel triangular support frame 10 will be dismantled, following the order of "dismantling the last installed components first and dismantling the first installed components last".

[0054] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A construction method for a shared operating platform for the cantilever structure support and protective frame of an aerial helipad, characterized in that, The process includes the following: Step 1: Design and calculation of cantilevered steel triangular support frame (10); Step 2: BIM modeling and construction simulation; Step 3: Prefabrication and overall hoisting of cantilevered steel triangular support frame (10) in the factory; Step 4: Set up strain monitoring points on the cantilevered steel triangular support frame (10); Step 5: Simultaneously erect an inner support frame and an outer protective scaffold (2) on the cantilevered steel triangular support frame (10) to form an operating platform system that combines support and protection; Step 6: Construction of the cantilevered structure of the helipad, including three sub-processes: steel reinforcement, formwork, and concrete work; Step 7: Overall strain monitoring of the cantilevered steel triangular support frame (10); Step 8: Dismantle the scaffold.

2. The construction method for the shared operating platform of the cantilever structure support and protective frame of the high-altitude helipad according to claim 1, characterized in that, The cantilevered steel triangular support frame (10) includes an upper chord (5), a lower chord (6), a web member (7), and a secondary beam (4). The upper chord (5) and the lower chord (6) are welded to the embedded parts (3) of the structural floor. The web member (7) is welded between the upper chord (5) and the lower chord (6) to form a triangular structure. The secondary beam (4) is welded to the upper surface of the upper chord (5) and is used to connect with the external protective scaffold (2), the internal support frame, and the template support frame of the cantilevered structure of the helipad.

3. The construction method for the shared operating platform of the cantilever structure support and protective frame of the high-altitude helipad according to claim 1, characterized in that, In step 5, the external protective scaffold (2) is connected to the structural floor using wall ties (8), and the cantilever height of the wall ties (8) is controlled to be less than 4m. When the cantilever height of the wall ties (8) is greater than 4m, temporary bracing and fixing measures are taken between the internal support frame and the external protective scaffold (2) to enhance the overall stability of the frame. After the internal and external frames are temporarily braced, the connection must be released before the concrete is poured on the cantilever structure of the helipad to avoid deformation of the frame during the concrete pouring process, which would affect the structural quality.

4. The construction method for the shared operating platform of the cantilever structure support and protective frame of the high-altitude helipad according to claim 1, characterized in that, In step 6, the reinforcement work includes: HRB400 grade steel bars are used for the cantilever slab of the helipad. Before the steel bars are tied, the positioning lines are marked on the formwork to ensure accurate spacing of the steel bars; stirrups are set on the upper layer of the cantilever slab reinforcement with a spacing of 1000mm to prevent displacement of the steel bars during concrete pouring; in the dense area of ​​the beam-column joint reinforcement, staggered tying method is used to ensure the quality of concrete pouring; the steel bar connection adopts lap splicing, and the lap length and anchorage length are implemented in accordance with design requirements and specifications.

5. The construction method for the shared operating platform of the cantilever structure support and protective frame of the high-altitude helipad according to claim 1, characterized in that, In step 6, the formwork engineering includes: the cantilever slab formwork of the helipad is made of 15mm thick plywood, the secondary keel is made of square steel pipe with a cross-sectional size of 40×40×20mm and a spacing of 200mm, and the main keel is made of square steel pipe with a cross-sectional size of 100×50×25mm; the formwork support frame is a disc buckle support frame (1), with a vertical spacing of 0.9m or 1.2m, a horizontal spacing of 1.5m, and a step spacing of 1.5m. When the span of the cast-in-place reinforced concrete slab is greater than 4m, the formwork is arched at 1 / 1000 to 3 / 1000 of the span, the cantilever length of the adjustable support extending out of the top horizontal bar does not exceed 600mm, and the exposed length of the threaded rod does not exceed 400mm.

6. The construction method for the shared operating platform of the cantilever structure support and protective frame of the high-altitude helipad according to claim 1, characterized in that, In step 6, the concrete work includes: the concrete strength grade of the cantilever slab of the helipad is C30, and the slump requirement is 180±20mm; a concrete placing boom is used for pouring, and the cantilever slab is poured from the outside to the inside, continuously moving forward. When the reinforcement at the joints is dense, a small-diameter vibrator is used for vibration, and the vibrator points are increased; the loose thickness of the concrete for the cantilever slab is greater than the slab thickness. After vibration, it is leveled with a screed and smoothed with a trowel. The elevation of the slab surface is checked with a string line to control the flatness; the concrete is covered and cured after pouring.

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