Four factors: basic parameters, installation method, height, environment tower crane
Four factors: basic parameters, installation method, height, environment
1. Determination of basic parameters
The basic parameters of the tower crane are the height of the tower crane, the length of the arm, and the maximum hanging weight of the arm(ie, the farthest end of the tower crane arm). Except for very special cases, the maximum lifting weight of the tower crane generally does not need to be considered. According to the length, width and height of the building, the arm length of the tower can be initially determined. The arm length is appropriate to ensure that it can cover all projects and have a slight margin.
The tower cranes that are often seen at present are generally 30m, 40m, 50M, 55m, 60m, 70M, and several types. The tower cranes with larger arm lengths are rarely used by other conditions on the scene. Caution is required when selecting. The height of the tower is as long as it is 10 to 15M higher than the maximum Gaodu Gaochu of the building. The weight of the arm end is determined by the weight of the object to be lifted by the civil construction workers. General frame structure type buildings, because the tower crane needs to be lifted concrete bucket, the weight of the arm is larger; Now the concrete structure of the high-rise buildings, this requirement is lower. After the above three parameters are determined, the type of tower crane can be initially determined.
2. Determination of installation modalities
The tower crane is a device used on the ground. Its own weight(1Ot ~ 200t) is much larger than the general construction machinery. Therefore, the installation of the tower crane foundation is also one of the main issues that needs to be considered when selecting. At present, there are three basic installation methods for self-rising tower cranes: fixed feet in large concrete blocks, pressurized weights in large chassis, and walking installation methods. Different installation methods have different requirements for the ground pressure of the basic soil(15-20t/m2, and different types of Tower cranes have different pressure on the ground. In addition, the foundation depth and slope type of the project also affect the installation of the tower foundation. This in turn affects the selection of Tower cranes. This point requires that the selected person has some practical experience and carefully read the chapter on the basic part of the product description of the proposed tower crane before determining.
3 Kai by height determination
Commonly used self-ascending tower cranes can rise with the elevation of the building. When the height of the tower crane exceeds the "free height", if it rises again, it is necessary to adopt the "attached wall" measure. It is to "anchor" the tower with the project under construction. Different types of Tower cranes have different heights for the first time, and the distance between each "attached wall" is also different. The attached wall of the tower crane has an additional lateral tension in the construction, which requires that the completed part of the project can achieve a certain strength. If the construction speed is fast and the attached wall part has not yet reached the scheduled strength, this will affect the construction progress. In this case, consideration should be given to choosing a type of tower crane with a higher free height. And it is particularly important in winter construction.
4 Impact of the 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 structure of the tower crane is longer and heavier. It is generally 10m long. It requires large transport vehicles and large-tonnage car cranes when it is installed. After the completion of the project, it will need to be removed with the same equipment. Therefore, the surrounding environment also has a certain restriction on the selection of Tower cranes. Sometimes only one ton of tower can be completed during construction. However, due to the constraints of the surrounding environment, it is necessary to choose two smaller tonnage tower cranes before construction; On the contrary, sometimes only a small tonnage tower crane is required. If you want to solve this problem well, after the preliminary determination of the tower lifting type, you can find a professional tower lifting and assembling unit(which requires the qualifications approved by the local construction committee) to be finalized after on-site investigation.
