The most fire prevention method for tower crane ov

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Methods to prevent the tower crane from overturning (1)

with the development of a) the machine adopts the domestic original dual up and down microcomputer controller (LCD and computer can be controlled separately or double control), the degree of mechanization of building construction has increased year by year. As a machine that can transport materials vertically and horizontally, the tower crane (hereinafter referred to as the tower crane) especially because of its high lifting height, large lifting weight It has been widely used in the construction industry. However, due to the large structure of the tower crane and the high-altitude operation, the tower crane overturning accident is easy to occur. These accidents not only affect the progress of construction, but also bring huge losses of life and property to the country and people

at the international crane safety and management conference held in London in 2006, Mr. klausmeissner, R & D director of Terex, pointed out that regular and irregular effective inspection of cranes is one of the keys to avoid crane safety accidents. Charlesgillespie from the UK emphasized in his speech that the key to ensure hoisting safety is to provide safety operation training for employees and improve their safety awareness. Mr. tsutomuhashimoto of Japan Crane Association also mentioned that the goal of Japan Crane Association is to avoid various crane accidents as much as possible through technical research and research, education and training, information release, inspection and detection and other means. It is also mentioned in document 5 that the maximum amplitude (minimum angle) limiter should also be set for the boom luffing tower crane, because once the jib exceeds the specified angle, its root is very likely to be damaged immediately, and even cause the tower crane to overturn. It can be seen that the safe use of tower crane has become a concern

at present, tower cranes are equipped with safety limit devices, mainly including lifting capacity limit device, lifting torque limit device, amplitude limit device, lifting height limit device and rotation limit device. The function of the safety device is to automatically cut off the power supply when the tower crane exceeds the set value during use, so as to prevent tower crane accidents. Although the safety device of the tower crane can provide safety protection for various working conditions of the tower crane, the tower crane falling accident can not be avoided. It is analyzed that the reason for the tower crane falling accident is not that the tower crane is not equipped with a safety limit device, but that the tower crane is inclined to pull and pull out the pile during the hoisting process, and the foundation of the tower crane is immersed in water, resulting in different settlement of the foundation pile, causing the tower body to tilt, and the scaffold is hung during the hoisting process, During the hoisting process, the heavy objects are not tied firmly, the sudden unloading of the heavy objects causes the sudden increase of the tower crane's back tilt force, the loose connection of the tower crane's standard section fixing bolts and slewing bearings, the cracking of the welds at the tower foundation section and the excessive initial installation angle of the tower crane, which make the tower crane prone to overturning accidents during the hoisting process. For example, on November 22nd, 2005, a tower crane produced by a factory had a brittle fracture accident at the joint of the tower body foundation section in Yibin City, Sichuan Province. The accident was due to the occurrence of micro cracks due to unreasonable welding process and the unqualified elongation of the base metal, which inevitably led to brittle fracture. A tower crane overturning accident in Chengdu in 2003 was caused by poor drainage of the tower crane foundation for a long time, and the fillet weld on the back of the flange connecting the underframe and the foundation was corroded by mud and water for a long time, which made the effective height of the weld predicted by GGII smaller and smaller. Because the fillet weld was not easy to be found, when the rated load was hoisted, the fillet weld was torn, resulting in the overall collapse of the tower crane from the root. The driver of a tower crane in Pudong New Area of Shanghai failed to carry out pre shift inspection. As a result, the tower crane overturned due to the loose bolts fixing the tower foundation. On december24,2001, a qtz40c tower crane at a construction site was damaged due to illegal operation (the sleeve embedded in the ground was dropped for two consecutive times, and the sleeve was not pulled out twice, resulting in overload, cracks and plastic deformation of the tower body). Without inspection, the damage of the fixed foundation base of the tower crane continued to expand, causing the tower crane to tip over

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