Application of the hottest external hanging liftin

Application of external lifting scaffold in high-rise building construction

a building was originally designed to have 43 floors above the ground, but later, due to various factors, it was temporarily constructed to 24 floors, 2 floors underground (the main building also has a mezzanine), and 5 floors above the ground of the podium. The main building is an outer frame and inner tube structure. The standard floor height is 3.9 meters (the quotient of 15 and 24 floors is 4.8 meters), and the outer edge size is 36.4m × 33.4m. For the external protective frame during the structural construction, it was originally planned to use the lifting scaffold developed by Shanbao technology development company of Peking University. Later, due to the large scale adjustment, it was changed to use the external hanging lifting scaffold

1. Scaffold design

1.1. The plane layout adopts the small flow technology to organize the construction, and the standard floor is divided into two sections from the middle, so the shelves are also arranged from the middle of ⑦ and ⑧ axes to both ends. The shelves are disconnected at the attachment of the corresponding tower crane and the external elevator, and the local protection is treated separately by a single bent. The plane layout is shown in figure

1.1.2. The width of the frame structure is generally 6 meters, in order to ensure that the adjacent frames will not be affected during lifting, The distance between each two shelves is 20-30cm, and the width of shelves that do not conform to the module can be adjusted by shortening the steel pipe. The total height of the shelf is 10 meters on the outside (6 meters plus 4 meters steel pipe combination), and 6 meters on the inside. The protective height is about 2 meters higher than the height of the two standard floors. For the increase of the height of the 15 and 24 floors, a single row protective frame is temporarily erected during construction, which can fully meet the safety protection requirements of the edge during construction. In order to increase the integrity of the frame, a diagonal tie rod is set at both ends to connect the inner and outer vertical rods, which is similar to the corridor diagonal rod of the climbing frame. The steel pipe passing through the floor slab is not only beneficial to the low-speed experiment of conventional materials (metal, cement, concrete, etc.), but also plays the role of pulling and connecting the external protective frame. It can also be used to establish the external protection of the lower floor, providing safety guarantee for formwork removal and masonry. The outer side of each shelf is fully hung with dense eyes for safety, and the gap between the two shelves is safely closed with a narrow width. In case of accident, each shelf is equipped with two safety wire ropes（ φ 12.5 Bo Chuang places the mold locking cylinder at the back of the movable formwork, 6 × 19) , fastened with basket bolts, which increases the safety assurance factor

1.3. Take the 6m wide frame as an example for structural calculation. See figure 5.2g for the simplified structural calculation model. G is the dead load and live load transmitted from the pole, t is the tensile force borne by the tie rod, and F is the external overturning force. According to the regulations of the safety technical operation specification for socket racks widely used in Beijing, the construction live load of the pylon shall not exceed 1.2kn/m2, and the calculated 2G load combination value is 27kn After calculation, the wind load is taken as 0.133kn/m2 Based on this, the maximum pressure nmax, local stability (slenderness ratio of single limb), overturning resistance and allowable tension of safety wire rope are calculated respectively, which meet the requirements

2. Scaffold construction

2.1. Scaffold erection and demolition. The main building is connected with the podium below the 6th floor, and the external protection adopts double row scaffold. When the construction reaches the 7th floor, the external protective frame will be separated from the lower frame, and only the temporary diagonal support rod will be extended to the 6th floor. After the construction of the 8th floor roof, the frame can be completed. After hanging the steel wire rope, connecting the extension rod, and adding the diagonal support rod, the temporary support on the 6th floor can be removed. When the conditions are met, the frame can be lifted

after the structural construction is completed, each piece of rack shall be lifted directly to the ground and removed in pieces

2.2. The scaffold shall be lifted after the floor concrete has a certain strength, and it shall be pushed from the middle of ⑦ and ⑧ axes to both sides

the distance between the outer protective frame and the structural edge is designed to be 20cm. Although it is adjustable, it cannot be too large. Therefore, the extension length of the supporting steel pipe of the outer side beam formwork cannot exceed a certain limit, otherwise it will affect the lifting. Each shift consists of 7 people, including 1 signalman, 1 monitor and 5 others. The scaffold board and safety on each hoisting unit are erected at one time. During lifting, only the pull rod and the narrow safety between each two shelves need to be removed and re fixed. Generally, one shelf can be lifted in 20 minutes