With the continuous development of the national construction industry, the unloading platform, as an indispensable part of building construction, is currently erected on construction sites in accordance with the specification *"Technical Code for Safety of Working at Height in Building Construction" (JGJ80-2016)*. This specification explicitly outlines the following technical requirements for the erection of unloading platforms:

Technical Code for Safety of Working at Height in Building Construction (JGJ80-2016)

(Cantilevered Unloading Platform)

(1) In principle, the use of floor-standing (ground-based) unloading platforms is strictly prohibited. The active promotion and use of tool-type, modular prefabricated cantilevered unloading platforms made of section steel is encouraged.

(Cantilevered Unloading Platform)

• Cantilevered unloading platforms shall use I-steel or channel steel of size 16 or larger as main beams and secondary beams. Wooden planks with a thickness of not less than 50mm shall be laid on top and fixed to the cantilever beams with bolts.

• The cantilevered unloading platform must be supported on the building structure and must not be connected to the scaffold. It shall not exhibit forward/backward movement or left/right shaking.

(III)

(1) The portion of the cantilever beams extending into the building shall be no less than 1 meter. They shall be fixed to the building structure at no fewer than two points using steel bars or bolts of not less than φ16.

(2) The cantilever beams on both sides shall be tension-relieved using at least two φ14 steel wire ropes for吊拉卸荷 (lifting and unloading). The upper connection points of the steel wire ropes must be fixed to the building structure; it is strictly prohibited to set them on masonry walls, scaffolds, or other construction equipment. Where steel wire ropes pass over sharp edges and corners of the building, soft padding shall be added. The outer edge of the unloading platform should be slightly higher than the inner edge, and the platform should be installed levelly.

(IV) The unloading platform must be equipped with protective railings and toe boards according to the requirements for edge work. The height of the top railing shall be 1.2m, the height of the middle railing shall be 0.6m, and the height of the toe board shall not be less than 18cm. The railings must be fully covered with dense safety nets from top to bottom.

(V) The unloading platform shall be provided with 4 verified lifting lugs. The lifting lugs shall be made of Q235 steel reinforcement. (The lifting lugs should be预埋 (embedded) in the main structure, with their embedment depth and anchorage length conforming to specified values. The net height of the lifting lug above the concrete surface shall not exceed 5-6 cm, and the direction of the lifting lug shall be perpendicular to the floor surface.)

(Note: Key technical data such as steel beam sizes (16+), plank thickness (50mm), fixing points (≥2), wire rope size (φ14+), railing heights (1.2m/0.6m), toe board height (18cm), lug material (Q235), and embedment details (5-6cm protrusion) have been preserved accurately. The Chinese specification code JGJ80-2016 and technical terms like 预埋 (embedded) and 吊拉卸荷 (tension-relieved/lifting and unloading) have been translated precisely for engineering contexts.)

Please let me know if you need adjustments for a specific dialect of English or additional technical explanations for any of these safety requirements.

(Cantilevered Unloading Platform)

(VI)

(1) The angle between the steel wire rope of the unloading platform and the horizontal cantilever beam should preferably be between 45° and 60°. When fixing the steel wire rope of the unloading platform with rope clips, no fewer than 3 fixing clips shall be used, and the distance from the last rope clip to the rope end shall not be less than 140mm.

(2) A rope bend (sling eye/thimble) should be provided between the last rope clip and the second rope clip. The saddle of the rope clip shall be placed on the live end (the side bearing the load when the wire rope is tensioned). The "U" bolt shall be placed on the dead end (tail end) of the wire rope, and clips must not be installed staggered in reverse directions. After initial fixing with rope clips, they shall be re-tightened after the wire rope has been placed under load, and should be tightened until the rope diameter is compressed and flattened by approximately 1/3 of its original height.

(VII) A unified weight limit sign board issued by the branch company shall be hung on the platform, indicating: the rated load limit (in tons), and the persons responsible for acceptance, maintenance, and installation. Overloading or long-term stacking of materials is strictly prohibited. Materials shall be hoisted promptly after being placed on the platform. The stacking height of materials shall not exceed the height of the platform guardrails. The number of workers on the platform is limited to 1-2 persons. Using the platform as a rest area is strictly prohibited. The total weight of construction personnel and materials on the platform shall never exceed the designed allowable load.

(VIII) The entrance/exit opening of the unloading platform must be equipped with compliant rigid protection (hard).

(IX) After the erection of the unloading platform is completed, it must undergo acceptance inspection by construction technicians and full-time safety management personnel. It can only be put into use after confirming compliance with design requirements, signing off on the acceptance意见 (comments/report), and completing the acceptance procedures.

Additional Reference Information:

Standard dimensions for cantilevered unloading platforms in building construction:

(1) Design dimensions of the cantilevered unloading platform: Steel platform length 4.5m, width 2m. Main and secondary beams are fabricated using 16# and 10# channel steel respectively. Steel wire ropes use a diameter of 20mm.

(2) Allowable loads: Construction live load 2KN/m², concentrated load 10KN.

Based on the characteristics of the above technical specifications, it can be observed that this type of cantilevered unloading platform initially uses U-shaped anchors passing through the floor slabs for fixation, which can lead to floor leakage. In later stages, this was changed to One-time Bend Fastener  (one-time bend fasteners) embedded in the floor. However, the embedding cost is high, and direct cutting is required during dismantling, making Secondary Reuse (secondary reuse) impossible. It can only be moved progressively from lower to upper floors and is only suitable for transferring formwork and supports for up to three floors. This product cannot be retracted or moved; it is a fixed structure with relatively low hoisting efficiency. Furthermore, workers operate outside the building wall, presenting significant safety hazards. Additionally, the platform has four diagonal upper Cable (cables) on the outer cantilevered side, which hinders the hoisting of materials and affects efficiency. It lacks an intelligent overload control alarm system, making it highly prone to overloading and collapse accidents.

This product is a fully automatic intelligently controlled mobile and retractable construction site unloading platform, which excellently solves the three problems mentioned above. Moreover, due to its two-layer load-sharing design, the designed concentrated load of this product can reach over 20KN.

The following is a specific description of this product:

The automated retractable unloading platform consists of two layers: the upper layer is the load-bearing platform, and the lower layer is the driving trolley platform. The two layers are connected by strut rods (two-force members). The load-bearing platform, driving trolley platform, support rods, and tracks are all welded to form a planar load-bearing frame. The tracks are fixed to the floor slab. Both the load-bearing platform and the driving trolley platform travel along these tracks.

Features:

1. Convenient Operation, Safe and Reliable
When the platform is hoisting goods, there is no interference from cables, improving hoisting efficiency. The platform can automatically retract and extend, enhancing loading and unloading efficiency. Personnel operate from within the building, avoiding safety hazards associated with working at height.

2. Real-time Load Measurement, Better Stability
The support rods of the automated retractable unloading platform are two-force members. The load-bearing platform and the trolley platform move in and out simultaneously, maintaining a fixed angle for the support rods. The force measured by pressure sensors installed at the hinge points between the trolley platform and the support rods can directly calculate the weight applied to the load-bearing platform by the construction materials. The automated retractable unloading platform adopts automatic control. When pressure sensors detect that the load on the platform exceeds the limit, the controller prevents the hoisting equipment and drive mechanism from starting. Simultaneously, an audible alarm sounds to indicate overload, preventing operation.

3. Energy Saving and Environmental Protection
In traditional building construction material handling, concrete accounts for approximately 50%, steel reinforcement 30%, and formwork supports 20%. Currently, as concrete is transported using pumping methods, the workload is reduced by about 50%. The current handling work primarily involves transporting steel reinforcement, formwork, and partition bricks via hoists. Based on a calculation for one floor with four units, each of 150 square meters, where the partition wall area is three times the floor area, the volume of partition bricks per floor is approximately 1800 cubic meters. Partition bricks are 20cm thick, with each cubic meter capable of (building) 5 square meters. The quantity of partition bricks needed per floor is 1800 / 5 = 360 cubic meters. Assuming a hoist transports 2 cubic meters per trip, 180 round trips are required. At 6 trips per hour, this takes 4-5 days. The cost of using the hoist is as follows:

• Hoist installed capacity: 60KW. Calculation: 4.5 days × 8 hours × 60KW = 2160 kWh. Electricity cost at 1.1 yuan/kWh: 2376 yuan.

• Hoist operator labor cost: Average daily cost per person: 4500 / 30 = 150 yuan. 150 yuan × 2 persons (double cage) = 300 yuan. 4.5 days × 300 yuan = 1350 yuan.

• Hoist rental: 12,000 yuan per month, i.e., 12000 / 30 = 400 yuan per day. 4.5 days × 400 yuan = 1800 yuan.

• Horizontal transportation labor cost for bricks per cubic meter: According to national standards, within a 50-60 meter transportation range, it is 0.4 labor days per cubic meter, approximately 200 yuan/day × 0.4 labor days = 80 yuan. Total horizontal labor cost: 80 × 360 = 28,800 yuan.

Total cost for transporting partition bricks per floor (sum of above) = Hoist rental + Hoist electricity + Hoist operator labor + Horizontal transportation cost = 1800 + 2376 + 1350 + 28800 = 34,326 yuan.

(The above does not include management costs such as roads, environmental treatment, transportation machinery, and transfer sites.)

Using the automated retractable platform for transportation, the construction party makes procurement plans according to the budget. All interior finishing materials, from the manufacturer to the site, are directly hoisted from the transport vehicle onto the construction floor. This saves all the costs mentioned above, achieving  (green construction throughout the entire process).

In summary, the use of the automated retractable platform improves tower crane utilization, reduces the cost of handling interior finishing materials, creates favorable conditions for civilized construction, and achieves the goal of enhancing enterprise management efficiency.

Conclusion: Historically, the upgrading of demands from the government and consumers has always been the long-term, core driving factor for the intelligent and green development of the construction market. This product starts from solving practical problems, improving efficiency, reducing handling labor and electricity consumption, and enhancing safety. By adopting automation and intelligent control, it will make corresponding contributions to the green and intelligent development of the construction industry.