Disassembly of tower crane installed in the middle

2022-08-03
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Disassembly of tower crane installed in the middle of large multi-storey buildings

the installation of tower crane changes with the change of building state. Generally, the tower crane is installed outside the building, which can not only meet the needs of building construction, but also have no problem in the disassembly and assembly of the tower crane itself. However, in recent years, we have encountered foreign-invested buildings with large area and low building height, such as Jinjiang SM square, Xiamen SM square, Quanzhou Fengze commercial city and Yong'an chemical fiber differential technical transformation project. For example, Xiamen SM square has a length x width of 285m × 15m high and 32m high, the structure is a large-span on-site steel stranded prestressed beam. Most of the tower cranes of our company are 60tm with arm length of 45-50m. If the tower cranes are installed outside the building as usual, the number of tower cranes will increase, and there is still a large area in the middle that cannot be covered, which is neither economical nor can meet the needs of construction. Therefore, the construction organization design requires that the tower cranes be installed in the middle of the building. However, this scheme must solve the problem of how to dismantle the tower crane after construction. After repeated discussion and comparison, a more practical scheme is designed. In five projects (all completed), the dismantlement effect of 8 tower cranes of 25, 60 and 120tm is very good. Now it is introduced as follows. 1. the original plan for dismantling machines and tools was to use two machine and tool schemes: ① make a special small crane for the foam granulator surface; ② With a single lever, but encountered difficulties in implementation. For scheme ①, it will take a period of time to design and manufacture a special crane. The main reason is that the investment cost is large, and there may be few opportunities for reuse. Moreover, the dismantling of the special crane on the roof after dismantling the tower crane is a problem; As for the ② scheme, most of the company are young workers at present. They are not familiar with the use of the last customer who went to other places to see the sole pole. In particular, the tower crane assembly has large mass, large size and large displacement. There are even more unsafe hidden dangers when using this tool. After analysis, it is considered that to dismantle the tower crane, the dismantling equipment can only have the functions of lifting and horizontal displacement, while the manual single beam trolley can have these two functions. In addition, the supporting I-beam can be built with the steel pipe frame of the site and set up according to the high and low quality of the disassembled parts. In this way, the dismantling equipment can be formed. We can disassemble the maximum assembly mass according to the company's tower crane models. Size purchase 2 10t single beam trolleys, 5tl trolleys, 1 8m50i steel and 1 3m25i steel produced by Zhengzhou crane factory, and 2 ready-made 3 and 5T hoists. This set of machines and tools is characterized by simplicity, convenience and flexibility. It can be installed, used and disassembled at any time; The investment is small, only a few thousand yuan in total; The technical requirements for operators are not high, and ordinary personnel can operate; The dismantling cost is about the same as that of the general tower crane; It is not necessary to embed anchors on the roof for the erection of machines and tools. The disadvantage is that there are many manual operations, but the intensity is not large. 2. installation of tower crane the method and steps of installing the tower crane in the middle of the building are exactly the same as those of ordinary tower cranes. Only two cases need to be considered: ① for buildings with holes, generally large-area buildings have holes in the middle for collecting light, gas and other functions, and the tower crane can be installed in the middle of the hole; ② For buildings without holes, 3M can be reserved at the post cast strip of each floor slab × For the hole about 4.5m, the tower crane is installed in this room. After the tower crane is removed, the hole and the post cast strip will be poured together. It should be noted that in order to facilitate the tower crane to lift various materials, the methods and means for extending and calibrating the boom end are basically 1 to a few meters outside the building. 3. specific steps for disassembly 1) tower lowering: lower the tower crane to the height where the balance weight is closest to the roof. 2) Unloading the counterweight: firstly, set up steel pipe racks

(three rows and two rows are determined according to the situation, with a spacing of 60cm) on both sides of the balance arm, put a cross beam on it, top it with 25i-steel, and hang a 5T car, which is like a gantry crane. Lift out and remove the balance weight piece by piece, but leave one piece flat on the boom frame according to the instructions to balance the lowering of the boom. 3) Lowering the tower body: lower the tower body to the front and rear arms and place them on the top plate. In order to make the pull plate of the front and rear arms loose and easy to remove, the ends of the front and rear arms shall be padded with wood to make the two arms tilt up and the pull plate loose. 4) Remove the front and rear pull plates. 5) Unloading the rear boom: use the gantry crane originally built on the rear boom to lift and unload the rear boom. 6) Remove the forearm: since the forearm has been attached to the top plate, you can manually remove one section of the forearm and put it on the plate. 7) Remove the cab. 8) Unloading the assembly to the ground: place the steel pipe and plate pad under the disassembled parts of the front and rear arms and the counterweight, use it or 0.st winch to drag it to the edge of the top plate, and use a 30t truck crane or a tower crane installed on the outside to lift the edge assembly to the ground. So far, the work above the roof has been completed. 9) Lower the tower body again: pull out the tower sections and put them on the floor to the bottom. 10) Erection and disassembly of machines and tools: the machines and tools for dismantling other assemblies of the tower crane shall be erected on the appropriate floor plate (capable of supporting the stressed) at a height higher than the tower top, as shown in Figure 1. Place sleepers on both sides of the floor slab opening, and mount 50 pi-steel, which must be aligned and firmly supported as the lifting

beam, and hang two 10t trucks. 11) Lift the tower top and rotary assembly in sequence and move them horizontally to the position where they can be loaded and transported. It must be noted that sometimes the height of the tower top is large and should be decomposed into a single assembly. 12) Disassembly of the frame: because the frame has large quality, height and size, it needs to be put down for transportation after disassembly, so it is the most difficult to disassemble the frame in the whole disassembly process, and two trolleys should be used to cooperate. The trolley mutual lifting point is at the upper 1/4 position, and the trolley 2 lifting point is at the lower position. Trolley 1 suspends the frame at a certain height, and trolley 2 pulls up. At the same time, the trolleys start to lower each other and cooperate up and down to try to pull the frame horizontally. During this period, great horizontal force will be generated. As shown in the figure, the hoist should be used to pull against the horizontal force, and then it should be placed horizontally for outward transportation. 13) Finally, remove the brace, base and other components. So far, the whole tower crane has been disassembled

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