How to effectively prevent the tower crane from ov

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How to effectively prevent the tower crane from overturning

with the development of the construction industry, the degree of mechanization of construction has increased year by year. As a machine that can transport materials vertically and horizontally, the tower crane (tower crane for short) has been widely used in the construction industry, especially because its lifting height can be minimized, with high energy input, large lifting weight, large working range and other characteristics. However, due to the large structure of the tower crane and the high-altitude operation, the tower crane overturning accident is easy to occur

at the international crane safety and management conference held in London in 2006, klausmeissner, director of Terex research and development, 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 ensuring hoisting safety is to train employees in safe operation and improve their safety awareness. Mr. tsutomuhashimoto of the Japan Crane Association also mentioned that the goal of the Japan Crane Association is to avoid all kinds of crane accidents as much as possible through technical research and research, education and training, information disclosure, inspection and detection and other means. It is also mentioned in document 5 that it is suggested that emerging countries are also accelerating the opening-up and industrial structure adjustment of boom luffing tower cranes, and the planning machine should also be equipped with a maximum amplitude (minimum angle) limiter, because once the boom exceeds the specified angle, its root is likely to be damaged immediately, and even lead to tower 14. Accuracy of strain control rate: the rate is less than 0.05% FS/s, and the opportunity to overturn. It can be seen that the safe use of tower crane has become a problem of concern

at present, tower cranes are equipped with safety limit devices, mainly including lifting weight limit devices, lifting torque limit devices, amplitude limit devices, lifting height limit devices, and rotation limit devices. The function of the safety device is to automatically cut off the power supply once the tower crane exceeds the set value during use, so as to prevent the occurrence of tower crane accidents

although the tower crane safety device can provide safety protection for various working conditions of the tower crane, it still cannot avoid the tower crane falling accident. It is analyzed that the reason for the tower crane falling accident is not that the tower crane is not installed with a safety limit device, but that the tower crane is inclined to pull and pull the pile during the hoisting process, and the foundation pile 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 makes the tower crane's back tilt force suddenly increase, the connection of the tower crane's standard section fixing bolts and slewing bearings is loose, the welding seam at the tower foundation section is cracked, and the initial installation angle of the tower crane is too large, which makes the tower crane prone to overturning accidents during the hoisting process

for example, on November 22, 2005, a tower crane produced by a factory had a brittle fracture accident at the base joint of the tower body in Yibin City, Sichuan Province. The accident was due to the unreasonable welding process, resulting in the occurrence of microcracks, and the unqualified elongation of the base metal, which inevitably led to brittle fracture. A tower crane overturning accident occurred in Chengdu in 2003 was due to the long-term poor drainage of the tower crane foundation, 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, making the effective height of the weld smaller and smaller. Because the fillet weld is not easy to be found, when the rated load is hoisted, the fillet weld is torn, resulting in the overall collapse of the tower crane from the root. A tower crane in Pudong New Area of Shanghai overturned because the driver did not carry out pre shift inspection because the bolts fixing the tower foundation were loose

on December 24, 2001, the products of a downstream manufacturer of qtz40c tower crane at a construction site were still in the stage of R & D and trial production. Due to illegal operation (the sleeve embedded in the ground was unloaded twice in a row, and the sleeve was not pulled out twice, resulting in overload, cracks and plastic deformation of the tower body), the fixed foundation base of the tower crane was damaged. Without inspection, the extent of damage continued to expand when it continued to be used, causing the tower crane to tip over

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