Tower cranes are large-scale hoisting machinery commonly used in building construction. Due to the structural characteristics oftower craneS, the tower body bears relatively large eccentric bending moments. Dlatego, their installation and dismantling require strong technical skills, and safety management is rather difficult. A slight oversight can lead to major accidents with the destruction of the machine and loss of lives, causing huge losses to enterprises. The Ministry of Construction has always attached great importance to this work and has repeatedly listed tower cranes and other cranes as the key points of annual special governance. The installation and dismantling of tower cranes, because of the particularity of their structure, carry certain risks and are the stages wheretower craneaccidents are prone to occur. For this reason, the Ministry of Construction has specifically issued the “Notice on Further Strengthening the Management of Tower Cranes to Prevent Major Accidents”, strengthening and standardizing the management of tower crane installation, dismantling, and use. To effectively implement the spirit of the “Regulations on the Supervision and Administration of Special Equipment Safety”, the “Regulations on the Safety Production Management of Construction Projects”, and relevant documents of the Ministry of Construction, and to prevent tower crane installation and dismantling accidents, we must attach great importance to the safety management of tower crane installation and dismantling. Based on daily work practice, the author would like to share some opinions on the safety management of tower crane installation and dismantling.
I. Requirements for Tower Crane Installation and Dismantling Teams
The “Technical Specification for the Safe Use of Construction Machinery” (JGJ33 – 2001) clearly stipulates that “The installation and dismantling of tower cranes must be carried out by professional teams that have obtained the installation and dismantling qualification certificates issued by the construction administrative department, and technical and safety personnel should be present for supervision.” On January 28, 2008, the Ministry of Construction issued Order No. 166, “Regulations on the Safety Supervision and Administration of Construction Hoisting Machinery”. Article 10 further reiterates that “Units engaged in the installation and dismantling activities of construction hoisting machinery shall lawfully obtain the corresponding qualifications issued by the construction administrative department and the work safety production license of construction enterprises, and undertake the installation and dismantling projects of construction hoisting machinery within the scope of their qualifications.” Article 25 clearly requires that “Special operation personnel such as construction hoisting machinery installation and dismantling workers, hoisting signal workers, hoisting crane drivers, and rigging workers shall pass the assessment of the construction administrative department and obtain the special operation qualification certificates before they can start working…. The format of the special operation qualification certificates of special operation personnel shall be uniformly stipulated by the construction administrative department of the State Council.” Dlatego, when it comes to tower crane installation and dismantling, it is essential to select a proper installation and dismantling team. When choosing an installation and dismantling team, it is necessary to strictly review whether the installation and dismantling unit has the required qualifications and is equipped with corresponding professional and technical personnel. Any unit that does not meet the above requirements should be excluded from the construction market, and illegal teams should be consciously resisted, so as to lay a solid foundation for the safe installation and dismantling of tower cranes.
In the construction industry, the qualifications of the installation and dismantling team are the first line of defense for safety. The acquisition of proper qualifications indicates that the team has passed certain professional assessments, mastered relevant technical knowledge, and is familiar with safety regulations. Professional technical personnel play a crucial role. They are not only responsible for guiding the actual operation process but also for predicting potential safety hazards during installation and dismantling. Na przykład, they can analyze the stress distribution of the tower crane structure during disassembly based on its design drawings, and formulate reasonable disassembly sequences to avoid sudden structural failures. Safety personnel, on the other hand, are the guardians on the construction site. They constantly monitor the working environment, check whether workers are following safety procedures, and ensure that all safety protection measures are in place. Without strict review of the team’s qualifications, unqualified teams may enter the market, cutting corners in operation due to lack of professional knowledge and skills, which will greatly increase the risk of accidents.
II. Basic Work for Ensuring the Safe Installation and Dismantling of Tower Cranes
To ensure the smooth installation and dismantling of tower cranes, meticulous preparations should be made to create the necessary conditions for safe installation and dismantling.
1. Establish a tower crane use filing system
According to the requirements of the “Regulations on the Supervision and Administration of Special Equipment Safety”, during the manufacturing stage of tower cranes, local quality and technical supervision bureaus are responsible for review and inspection. Once the products leave the factory and enter the construction site, local construction administrative departments will take over the responsibility of controlling market access, implementing a registration and filing system for construction hoisting machinery. Detailed information about the hoisting machinery to be entered into the construction site will be input into a computer, so as to dynamically monitor the usage situation.
This filing system is of great significance. It is like building a database for tower cranes in the construction area. Through this system, the administrative department can clearly know the origin, model, and usage history of each tower crane. Na przykład, if there are any quality problems with a certain batch of tower cranes, the department can quickly trace back to all the construction sites using these tower cranes, and take timely preventive measures, such as notifying for special inspections. It also helps in overall planning. When the local construction volume changes, the department can adjust the distribution of tower cranes according to the usage records in the database, improving the utilization efficiency of equipment resources.
2. Carefully prepare before the tower crane enters the site
Although the required tower crane specifications have been clearly defined in the construction organization design, due to the influence and limitations of many factors such as the on-site environment and working conditions, some changes usually occur. Dlatego, relevant professional and technical personnel should jointly survey the site to optimize and select the most suitable tower crane for construction use. Before installation and dismantling, various factors should be fully considered, such as the site layout, soil conditions, surrounding obstacles (such as high-voltage lines and the safe operating distance from construction facilities), the expected lifting weight, the frequency of use, and the designed working level of the tower crane. It should not only meet the requirements of regulations and norms but also fully meet the needs of hoisting operations at the construction site, maximizing the role of the tower crane.
It should also be noted that an auxiliary crane is an essential machine for tower crane installation and dismantling. When choosing, it should meet the requirements of lifting height and weight, and also consider the bearing capacity of the road surface along the route of the auxiliary crane and whether there are any obstacle restrictions, so as to ensure its smooth return.
The selection of an appropriate tower crane is a complex but crucial task. The on-site environment is full of variables. Na przykład, in an urban construction site, the space may be narrow, and there are many surrounding buildings and power lines. In this case, a tower crane with a smaller turning radius and better height adaptability needs to be selected. The soil condition also affects the choice. Soft soil may require a tower crane with a more stable base design or additional foundation reinforcement measures. The auxiliary crane is equally important. If its lifting capacity is insufficient, it will be unable to complete the assembly and disassembly tasks of the tower crane components. And if the road conditions for its entry and exit are not considered, it may get stuck on the way, delaying the entire project progress.
III. Prepare the Tower Crane Installation and Dismantling Plan and Implement It Strictly
According to the requirements of the “Safety Regulations for Tower Cranes” (GB5144 – 2006), the “Operation Manual” randomly equipped with the tower crane is an important basis for guiding the installation, dismantling, and use of the tower crane, and must be followed. To ensure the safety management of tower crane installation and dismantling, it is necessary to carefully prepare the installation and dismantling plan, which is an extremely important task and an effective measure to ensure the safe installation and dismantling of the tower crane. The plan preparation must conform to the relevant content of the tower crane operation manual, as well as the installation and dismantling process and operating procedures. The main contents include: operation procedures and steps, quality requirements, safety technical measures, tools to be used, emergency plans, etc. It is generally prepared by professional and technical personnel and approved by the enterprise’s technical director.
After the installation and dismantling plan is prepared, it must be strictly implemented and cannot be changed at will. The installation and dismantling supervisor should organize relevant personnel (such as crane operators, mechanics, electricians, etc.) to hold a safety technical disclosure meeting at the construction site, so that the personnel involved in the installation and dismantling understand the installation and dismantling procedures and steps of this tower crane, master the key points of safety technology, and clarify their respective job responsibilities, ensuring the completion of the installation and dismantling tasks and effectively preventing accidents. The personnel involved in the installation and dismantling should also sign on the “Tower Crane Installation and Dismantling Safety Technical Disclosure Record Sheet” in a timely manner after the meeting and before starting work, and post-signing or signing on behalf of others is not allowed.
The tower crane installation and dismantling plan is like a roadmap for the entire project. It details every step from the initial disassembly of components to the final assembly and commissioning. Professional and technical personnel need to combine the actual situation of the tower crane model, the construction site environment, and existing resources when preparing the plan. Na przykład, in a coastal construction site with strong winds, special wind-resistant measures need to be added to the plan, such as strengthening the connection between components and increasing the stability of the foundation. The approval of the enterprise’s technical director is also a key link. The director, with rich experience and overall vision, can review the plan from a more comprehensive perspective, find potential safety risks, and make necessary improvements. The safety technical disclosure meeting is the key to implementation. Through face-to-face communication, workers can clearly understand what they should do, how to do it safely, and what to do in case of emergencies.
IV. Monitoring during the Installation and Dismantling Process
During the installation and dismantling process of tower cranes, the “installation and dismantling plan” should be strictly followed, and the monitoring work of each link should be done well, and the “Tower Crane Installation and Dismantling Process Record” should be filled in a timely manner.
1. Monitoring of tower crane foundation construction
The tower crane foundation is a prerequisite for ensuring its safe operation. The size of the foundation should meet the requirements of the “Operation Manual”. When the soil conditions at the construction site do not meet the requirements, the manufacturer’s design personnel should be invited to participate in formulating a modification plan according to the specific situation. For the most commonly used integral fixed foundation, according to the requirements of the “Technical Specification for the Safe Use of Construction Machinery” (JGJ33 – 2001), the concrete foundation should meet the following requirements: (1) The concrete strength grade is not lower than C35, and the foundation pit inspection should be jointly participated by the construction party, the equipment management party (if it is leased machinery, it is the leasing party), the supervisor, and the owner’s representative. (2) The steel bars, anchor bolts, concrete depth, and foundation unevenness used in the foundation should all meet the specification requirements. And the above test and inspection data should be truthfully filled in the “Building Engineering Concealed Inspection Record” as one of the safety technical management materials of the tower crane.
The tower crane foundation is the cornerstone of its stable operation. A solid foundation can evenly distribute the huge load of the tower crane to the ground, preventing uneven settlement and tipping. In different geological conditions, the design of the foundation needs to be adjusted accordingly. Na przykład, in rocky areas, the foundation may need to be blasted and leveled first, and then reinforced concrete is poured. In soft soil areas, pile foundations may be required to increase the bearing capacity. The joint participation of multiple parties in the foundation inspection also ensures fairness and strictness. Each party represents different interests, and together they can ensure that the foundation construction meets all requirements without any omissions.
2. Monitoring of the installation and dismantling procedures
Tower crane installation and dismantling follow strict procedures. What to do first and what to do next cannot be reversed. Each step is closely linked. Once illegal operations occur, serious consequences will follow. As the industry insiders commonly recognize, “Once something goes wrong with a tower crane, it will be a major accident.” This requires on-site technical and safety managers to earnestly guide and supervise the workers to strictly follow the installation and dismantling regulations, norms, and plans. No one is allowed to direct or operate illegally.
During the installation and dismantling monitoring, first, it is necessary to “check” whether the workers are correctly wearing and using safety protection articles; second, Do “examine” whether safe and feasible lifting tools, slings, and lifting points are correctly and reasonably selected; third, Do “judge” whether the handling of sudden events is proper and whether the emergency plan measures are feasible; fourth, Do “pay attention to” resolutely stopping those who violate the procedures, and not turning a blind eye; fifth, Do “strictly control” the quality of the whole installation and dismantling process, and urge the installation and dismantling personnel to adhere to and implement the “three-inspection” system.
The strict implementation of procedures is the guarantee of safety. In the tower crane installation and dismantling process, every small step may be related to overall safety. Na przykład, the selection of lifting points directly affects the balance of the lifted components. If the lifting points are selected incorrectly, the components may tilt during lifting, hitting surrounding objects or even causing the entire structure to collapse. Correct use of safety protection articles can also protect workers from potential injuries. Helmets can prevent head injuries from falling objects, and safety belts can save lives in case of accidental falls.
V. Detection and Acceptance
Detection and acceptance are the last procedures of tower crane installation and dismantling. When the installation and dismantling of the tower crane are completed, the detection and acceptance work should be done carefully. When the self-inspection is qualified, it should also be subject to the safety technical supervision inspection by the legal inspection agency. Only after a qualified report is issued can it be put into use.
1. Main bases for tower crane inspection
The “Regulations on the Supervision and Inspection of Hoisting Machinery”, the “Safety Regulations for Tower Cranes”, and the “Technical Conditions for Tower Cranes”.
2. Tower crane inspection items
They are respectively: technical data, working environment and appearance, metal structure, driver’s cab, foundation, track, main components and mechanisms, electrical system, safety devices and protection measures, and hydraulic system test. According to the requirements of the “Technical Conditions for Tower Cranes” (GB/T19462 – 1999): When the tower crane is installed to the independent height specified in the design, “The lateral perpendicularity of the tower body axis to the supporting surface in the no-load and windless state is 4/1000.” In addition, taking the rated load test in the test as an example: In the rated load test, according to the on-site situation, a corresponding rated lifting weight can be lifted at a certain amplitude, and the horizontal static displacement at the root of the jib should not be greater than H/100. After the test, first, it should be checked whether the crane has cracks, loose connections, damaged components, and other defects that affect the performance and safety of the crane; the focus should be on checking the reliability and sensitivity of the load limiter and the moment limiter, and the data meeting the specified values is considered qualified. It must be noted that the number of tests should be no less than 3 times, and various parameters should be measured and recorded.
Inspectors should carry out the detection and acceptance of tower cranes one by one according to the above bases and items, be meticulous and serious, and not be perfunctory. Hidden dangers should be discovered and eliminated in time to ensure the final quality of tower crane installation and dismantling.
The detection and acceptance stage is the final gatekeeper for tower crane safety. These inspection items cover all aspects of the tower crane, from the most basic technical data to the complex hydraulic system. The inspection of technical data can trace back to the origin and manufacturing process of the tower crane, ensuring that it meets the design standards. The inspection of the appearance and working environment can detect potential safety hazards caused by external factors, such as whether the corrosion of the metal structure due to the seaside environment affects its strength. The inspection of key components and safety devices is directly related to the operation safety of the tower crane. Through multiple rounds of strict inspections, only tower cranes that truly meet all safety standards can be put into use, protecting the safety of construction workers and the surrounding public.
In addition to the above key points, continuous training and education for tower crane operators and related personnel also play an important role in safety management. Regular safety training can update workers’ knowledge of new safety regulations, new equipment features, and new emergency handling methods. Na przykład, with the development of intelligent tower cranes, workers need to learn how to operate and maintain intelligent control systems. Psychological counseling can also be incorporated into the training. Tower crane operation is a high-pressure job, and reducing workers’ stress through psychological counseling can help them make more rational decisions during operation, further enhancing the overall safety level of tower crane installation, dismantling, and operation.
