Tower crane (hereinafter referred to as tower crane) is one of the indispensable construction machinery in building construction. Due to its own characteristics and special working methods, its selection is very different from other construction machinery. According to the determined structure and construction methods in the construction process, different types of tower cranes are selected. The main principle of the machine. In addition, the surrounding environment such as transportation roads, soil conditions, and underground structures also have a certain impact on the selection. 1. Determination of basic parameters The basic parameters of the tower crane refer to the height of the tower crane, the boom length and the maximum lifting weight of the boom end (that is, the farthest end of the tower crane boom). Except for very special circumstances, the maximum lifting weight of the tower crane generally does not need to be considered. The boom length of the tower crane can be preliminarily determined according to the length, width and height of the building. The arm length is appropriate to ensure that it can cover the entire project with a little margin. At present, the tower cranes that are frequently seen are generally 30m, 40m, 50m, 55m, 60m, 70m, and several kinds of tower cranes. Tower cranes with larger boom lengths are rarely used due to other conditions on the site, so be careful when choosing them. The height of the tower crane only needs to be 10-15m higher than the maximum height of the building. The lifting weight of the boom is determined by the weight of the object to be lifted given by the civil construction personnel. Generally, for buildings with frame structures, the tower crane needs to lift the concrete bucket, and the lifting weight at the arm ends is relatively large; however, the current high-rise buildings with concrete structures have lower requirements for this. After the above three parameters are determined, the type of tower crane can be initially determined. 2. Determination of installation method Tower crane is equipment used on the ground, and its own weight (10t～200t) is much larger than general construction machinery, so the basic installation method of tower crane is also one of the main issues that need to be considered when selecting. There are three basic installation methods for jack-up tower cranes commonly used at present: fixed feet installed in large concrete blocks, large chassis under pressure and walking installation methods. Different installation methods have different requirements on the ground pressure of the foundation soil (15-20t/m2, and different types of tower cranes have different pressures on the ground. In addition, the depth of the foundation and the type of slope also affect the installation method of the tower crane foundation. Affect the selection of the tower crane. This point requires the user to have certain practical experience, and carefully read the chapters of the basic part of the product manual of the tower crane to be selected. 3 The determination of the height The commonly used jack-up tower crane can rise as the building rises. When the height of the tower crane exceeds the "free height", if it rises again, the "attach wall" measure is required, which is to connect the tower crane to the The projects under construction are "anchored" together. Different types of tower cranes have different heights when they are attached to the wall for the first time, and the distance between each two "attached walls" is also different. The wall attached to the tower crane has an additional outward pull on the project under construction, which requires the completed part of the project to reach a certain strength. If the construction speed is fast, and the wall part has not reached the predetermined strength, this will affect the construction progress. In this case, the type of tower crane with larger free height should be considered. And it is especially important in winter construction. 4 Influence of surrounding environment The surrounding environment includes transportation roads, underground pipelines, the height of surrounding buildings and the presence or absence of high-voltage lines. The structural parts of the tower crane are longer and heavier, generally 10m long. Large transportation vehicles and large-tonnage truck cranes are required for installation. After the project is completed, it needs to be demolished with the same equipment. Therefore, the surrounding environment also restricts the selection of tower cranes. Sometimes a large-tonnage tower crane can be used to complete an ongoing project. However, due to the constraints of the surrounding environment, two tower cranes with smaller tonnage are used as a last resort; on the contrary, sometimes only one tower crane with small tonnage is needed. If you want to solve this problem well, after the tower crane selection is initially determined, you can find a professional tower crane disassembly and assembly unit (with the qualification approved by the local construction committee) to conduct a site survey before finalizing the model. 5. Consideration of other factors The above aspects are the selection principles for a single tower crane independent construction. When the height of the building is very high (more than 150m), you can consider using the internal climbing tower crane; when the building covers a large area and the shape is irregular, you should use multiple tower cranes of different sizes and heights to be configured together. The multiplying principle should not only cover completely, and not interfere with each other, but also place each tower crane in the most appropriate position according to the workload and work cycle. In addition, it should be noted that the power consumption of the tower crane is relatively large, generally tens of kilovolts, and the installation location should be as close as possible to the transformer on the construction site, while avoiding being too close to the high-voltage line. In short, the selection principle of tower crane has great uncertainty. In fact, the specific project should determine the corresponding tower crane type, and the small can not replace the big, nor can the big replace the small. Choosing a tower crane suitable for the project under construction requires personnel with practical experience in construction, machinery and installation to negotiate together to achieve a more satisfactory result. If there is a mistake in the selection, it may cause major economic losses or even accidents. Therefore, the selection of the tower crane is very important.