Tower crane as an indispensable vertical transport machinery for high-rise building construction, with the increasing prosperity of China's infrastructure, a large number of high-rise and super high-rise buildings continue to emerge, the height of the building is increasing day by day, which brings considerable difficulty to the application and layout of tower crane. How to arrange the position of the tower crane reasonably and solve the problem of the use of the tower crane is an urgent issue in front of people.

Usually, when the tower crane is used too high, the main problems are as follows:

First, the influence of the increase of wind load and self-weight on the strength and stability of tower crane structural parts

As the height of the tower increases, the weight of the tower crane increases, so it is necessary to check the strength and stability of the bottom tower. If the strength and stability are insufficient, it can be solved by the following methods, such as reducing the adhesion distance and reducing the calculation length of the tower to solve the overall stability problem of the tower. The strength and stability of a single limb can be ensured by increasing the wall thickness of the main chord.

The spacing of the attachment device is rationally arranged to improve the force of the tower body and the attachment device. After the tower crane is used excessively high, the wind load increases correspondingly due to the increase in the use height of the tower crane, the horizontal force borne by the tower body increases, and the bending moment at the end of the tower crane increases. In order to ensure the safety of the tower crane, Generally, the above problems can be solved by appropriately reducing the height of the tower crane cantilever end, lowering the climbing frame to the attachment frame or adjusting the spacing of the attachment device reasonably.

The reasonable arrangement of tower crane position and the choice of support and attachment form Different shapes of buildings, different construction technology, the method of tower crane arrangement should also be different, how to make a correct and reasonable choice, which is very important for the safety and economy of construction.

2、 The capacity rope problem of the lifting mechanism

The lifting height of the tower crane design has certain restrictions, but in order to meet the needs of building construction, the existing equipment can be used to make corresponding modifications to the tower crane under the most economical premise to meet the needs of ultra-high use, but the following issues need to be carefully considered. The lifting height is bound to increase the lifting wire rope, the general solution is to increase the length of the drum and increase the number of winding coils of the drum two methods, but it should be noted that if the method of increasing the length of the drum should consider the rope Angle problem, if it is to increase the number of winding coils of the drum in addition to considering the rope problem should also review the power of the lifting motor.

Third, the power and duration of the lifting motor

As the lifting height of the tower crane increases, the continuous working time of the motor increases, so the working system of the mechanism changes, so it is necessary to check the heating and continuous rate of the lifting motor to ensure the reliability of the lifting motor. If the experience is calculated, the working duration of the motor is not enough, it is necessary to take a series of measures to solve the problem, such as reducing the lifting load or lifting by stages.

Fourth, hoisting wire rope anti-winding problem

When the lifting degree of the tower crane exceeds the design value, because most of the lifting wire rope has its own winding, it is generally needed to release before wearing the lifting wire rope, although most of the tower crane arm head has a release device, but when the lifting height increases, the winding problem of the lifting wire rope becomes more and more serious, so that the lifting can not be carried out normally, the simple way is: This can be prevented by using anti-winding wire rope and increasing the distance between the two pulleys on the lifting trolley.

Five, the use of ultra-high tower crane disassembly

The disassembly of the tower crane is an important link in the safe use of the tower crane process, the disassembly of the tower crane has considerable technical and technological difficulties, especially the use of ultra-high large tower crane, due to its high height, the tower crane's single weight is large, so that it is relatively higher mechanical requirements for disassembly, and the top surface of the super high-rise building is small and complex.

At present, most of us use roof crane or mast crane to assist disassembly, for large tower cranes can first use a larger type of roof crane to disassemble, and then use a small roof crane to disassemble a large type of roof crane, and finally the small roof crane is disassembled and transported to the ground by manual method.

or some parts such as the boom, due to its center of gravity position is out, the weight of a single piece is larger, you can first use the lifting mechanism and the amplitude changing mechanism to disintegrate the part other than the tie rod, so that the weight of the boom is reduced, the center of gravity is shifted inward, so as to disassemble.