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The bearing capacity of the tower crane foundation ground should not be lower than the ground resistance value specified in the technical requirements of the tower crane foundation drawing.
The foundation of a tower crane is the key to its stable operation. The ground beneath it must possess sufficient strength to support the heavy loads and forces exerted by the crane. Engineers and construction teams need to conduct detailed geological surveys and calculations to determine the appropriate foundation design and ensure that the ground can bear the anticipated pressure. For example, if the specified ground resistance value is 200 kPa, the actual ground on which the foundation is to be poured must have a capacity equal to or greater than this value. Otherwise, the foundation may sink or shift, endangering the entire structure of the crane and the surrounding area.
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The pouring position of the tower crane foundation should be considered for the convenience of the installation and disassembly of the tower crane, avoiding all kinds of large obstacles.
When planning the location for the tower crane foundation, factors such as access for heavy machinery during installation and removal, as well as the presence of existing structures or natural features, must be taken into account. Placing the foundation in an area with numerous large boulders, for instance, would make it extremely difficult to install the crane components accurately. Similarly, if the foundation is too close to a building or other fixed structures, it could impede the crane’s movement during operation or create a hazard during installation and disassembly.
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The inclination of the horizontal plane formed by the four fixings of the tower crane foundation should not be greater than 1/1000.
This precise requirement is essential to maintain the vertical alignment of the tower crane. Even a slight deviation in the foundation’s level can cause the crane to lean, which can affect its lifting capacity and stability. Special leveling equipment and techniques are used during the foundation construction process to ensure that this tolerance is met. For example, laser leveling devices may be employed to achieve the required accuracy, and any discrepancies are corrected promptly.
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There should be no displacement of the tower crane foundation, and the ground should not have a collapse phenomenon. There should be drainage measures around the foundation, and no water accumulation should occur. The grounding pile should be driven as required.
A stable foundation is non-negotiable for a tower crane. Any movement or subsidence of the foundation can lead to catastrophic consequences. Adequate drainage is crucial to prevent water from eroding the ground beneath the foundation or causing hydrostatic pressure that could undermine its integrity. Grounding is also vital for electrical safety, protecting the crane and its operators from electrical shocks and ensuring the proper functioning of electrical components.
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The tower crane foundation pouring should avoid backfill land sections as much as possible. If it is unavoidable to use such sections, effective measures should be taken to make the ground bearing capacity meet the specified requirements.
Backfill soil is often less stable and has different engineering properties compared to natural, undisturbed ground. When backfill must be used, techniques such as soil compaction, adding stabilizing agents, or using geosynthetic materials may be employed to enhance its bearing capacity. This requires careful engineering analysis and implementation to ensure the safety and long-term stability of the foundation.
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When the tower crane foundation is poured on the foundation, the bottom surface of the foundation should generally be level with or slightly lower than the foundation pit. The soil quality and ground resistance of the foundation ground should be understood in advance. If there are phenomena such as underground rivers, quicksand, and sludge around the foundation ground, effective measures should be taken to make the ground bearing capacity meet the specified requirements.
Knowing the characteristics of the soil is essential for designing an appropriate foundation. If there are hidden geological hazards like underground rivers or quicksand, special foundation designs, such as pile foundations or caisson foundations, may be necessary to bypass or overcome these issues and ensure the foundation’s stability.
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When the tower crane foundation is poured on the side of the foundation pit, on the foundation pit retaining system or the underground continuous wall of the foundation pit, effective measures should be taken to strengthen the enclosure around the foundation and prevent the uneven settlement of the foundation, ensuring that the foundation does not have collapse, displacement, and inclination phenomena.
In such situations, additional structural support and reinforcement are required. This may involve installing retaining walls, using tiebacks or anchors, and closely monitoring the foundation’s settlement during and after construction. The goal is to create a stable and secure base for the tower crane, even in challenging geological or construction site conditions.
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When the tower crane foundation is poured on the natural ground far from the foundation pit, the ground resistance of the ground should meet the specified requirements, and the ground should be compacted after appropriate excavation.
Natural ground also needs to be evaluated and prepared. Excavation and compaction help to improve the soil’s density and bearing capacity. The depth and extent of excavation depend on the soil type and the crane’s load requirements. After compaction, the ground is tested to ensure it meets the necessary strength standards before the foundation is poured.
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The tower crane installation (disassembly) team should be a professional organization with corresponding qualifications, and its personnel must be trained and obtain valid operation certificates.
Qualified and trained personnel are the first line of defense in ensuring the safety of tower crane installation and disassembly. These professionals understand the intricate workings of the crane, the proper assembly procedures, and the safety protocols. They have the knowledge and skills to handle the heavy components, use the specialized tools, and follow the manufacturer’s instructions precisely.
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It is strictly prohibited for tower crane installation (disassembly) personnel to work under the influence of alcohol.
Alcohol impairs judgment, coordination, and reaction time, all of which are critical when working with heavy machinery and at heights. A single mistake due to intoxication can lead to serious accidents, endangering the lives of the workers and those in the vicinity of the construction site.
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Tower crane installation (disassembly) personnel should wear safety helmets, safety belts, and work shoes.
Personal protective equipment is essential for preventing injuries. Safety helmets protect the head from falling objects, safety belts prevent falls from heights, and work shoes provide traction and protection for the feet. These items should be of high quality and properly fitted to ensure maximum effectiveness.
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When working at heights, small items and tools should not be placed randomly in places where they are likely to fall. Generally, they should be placed on the platform or in the tool bag to prevent them from falling and injuring others.
Even small objects can cause significant harm when dropped from a height. Keeping tools and items secured reduces the risk of accidents and maintains a safe working environment. Workers should be trained of proper tool storage and handling at heights.
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The wind force during installation (disassembly) should not be greater than level 4. Installation (disassembly) should not be carried out in strong winds, thick fog, rain, or snow.
Adverse weather conditions, especially strong winds, can make it extremely difficult to control the large and heavy components of the tower crane during installation or disassembly. High winds can cause the components to sway, increasing the risk of collisions and accidents. Fog, rain, and snow can also reduce visibility and create slippery surfaces, further endangering the workers.
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Before installation (disassembly), the workers should understand the site situation, clear obstacles, determine the warning area, and prohibit irrelevant personnel from entering the work area.
A clear and safe work area is essential. Workers need to survey the site to identify any potential hazards or obstacles that could impede the installation or disassembly process. Establishing a warning area and restricting access ensures that only trained and authorized personnel are in the vicinity, reducing the risk of accidents involving bystanders.
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It is strictly prohibited to throw items downward from heights.
Throwing objects from a height is extremely dangerous and can cause serious injuries or even fatalities to those below. Workers should use proper lifting and lowering equipment and procedures to move items between different levels of the construction site.
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The connecting pins, shaft end clamping plates, bolts, nuts, and cotter pins of each part of the tower crane must be provided by the tower crane manufacturer or be special parts that meet the requirements and should not be randomly substituted.
Using the correct components is crucial for the integrity and safety of the tower crane. Manufacturer-supplied or approved parts are designed to fit precisely and withstand the specific forces and loads of the crane. Substituting with inferior or incorrect parts can lead to component failure, which could result in a catastrophic collapse of the crane.
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When the tower crane is installed, each pin shaft must be coated with grease. After installation, the cotter pin must be opened to the specified extent, the shaft end clamping plate must be fastened, and the connecting bolts must be tightened.
Proper lubrication and fastening of components are essential for the smooth operation and safety of the tower crane. Grease reduces friction and wear on the pin shafts, while properly installed cotter pins, clamped plates, and tightened bolts ensure that the components remain securely in place during operation.
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Only one person is allowed in the traction trolley basket each time.
The limited capacity of the trolley basket is based on safety and weight distribution considerations. Overloading the basket can affect the balance and stability of the crane, increasing the risk of accidents.
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When using the trolley basket for aerial work such as threading or disassembling the hook wire rope, only one person is allowed in the basket and must fasten the safety belt. When the trolley is carrying a person and running, the hoisting and slewing mechanisms are strictly prohibited from operating. The ground workers should ensure that the hoisting wire rope has no winding, tangling, or other phenomena.
These precautions are necessary to protect the worker in the basket and ensure the safe operation of the crane. The restrictions on the movement of other mechanisms while the trolley is manned prevent collisions and other accidents. The ground crew’s responsibility for the wire rope is crucial as any issues with the rope can lead to load drops or other dangerous situations.
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The installation (disassembly) should be carried out strictly in accordance with the order specified in the operation manual.
Following the manufacturer’s instructions is vital. The operation manual details the correct sequence of steps for installing or disassembling the tower crane. Deviating from this sequence can lead to improper assembly, misalignment of components, and ultimately, a less stable and safe crane.
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The tools, rigging, wire ropes, shackles for hoisting, and auxiliary lifting machinery used in installation (disassembly) must have good performance and meet the installation (disassembly) requirements.
Using reliable and suitable equipment is essential for a successful and safe installation or disassembly. Faulty or inadequate tools and machinery can lead to accidents, such as dropped components or equipment failures during the process.
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During the installation (disassembly) process, if sudden power outages, mechanical failures, or sudden weather changes occur and the work cannot continue, the installed (disassembled) parts must be made to reach a stable state, and all structural members must be connected firmly before stopping the work.
This precaution ensures that the partially assembled or disassembled crane does not pose a hazard. A stable and secure structure reduces the risk of collapse or other accidents during an interruption in the work process.
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Within one week after the tower crane is put into use, a special person should be arranged to tighten all the bolts of the tower body standard sections from bottom to top again. After that, a comprehensive inspection should be carried out every half month. If any bolt loosening is found, it should be tightened immediately.
Regular inspection and maintenance of the tower crane are crucial for its safe and continuous operation. Bolts can loosen over time due to vibrations and the dynamic loads of the crane’s operation. Tightening them regularly helps to maintain the structural integrity of the tower.
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After the tower crane installation is completed, there should be good drainage measures around the foundation. No facilities that affect the observation and tightening of the connecting bolts between the foundation section and the standard section are allowed to be erected around the foundation section.
Proper drainage around the foundation prevents water-related damage, and an unobstructed view of the bolts allows for easy inspection and maintenance. Facilities that block access or visibility can lead to overlooked maintenance issues and potential safety hazards.
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Tower crane drivers and signalers should be trained and qualified by relevant departments and hold valid operation certificates to take up their posts.
Proper training and certification ensure that the individuals operating and signaling for the tower crane have the necessary knowledge and skills. They understand the crane’s controls, safety features, and proper operating procedures, reducing the risk of errors and accidents.
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Within one week after the tower crane installation is completed and put into use, a special person should be sent to tighten the connecting bolts of the tower body from bottom to top again. After that, a comprehensive inspection should be carried out every half month, and it should be checked whether all the pin shafts and cotter pins are normal. If any bolt loosening is found, it should be tightened immediately.
Similar to the post-installation maintenance, regular inspection and tightening of bolts during the operational phase are essential for the crane’s safety. The repeated inspections help to catch any loosening that may occur due to the crane’s continuous use and dynamic loads.
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Tower crane drivers should conscientiously carry out shift handover work. For any problems existing during operation, the shift handover drivers must explain them clearly face to face. Only after proper handling can they start work, and shift handover records should be made well.
Effective shift handover ensures that any issues or concerns with the crane’s operation are communicated between drivers. This allows for continuous monitoring and timely resolution of problems, preventing potential accidents due to unnoticed issues.
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Before boarding the tower crane for operation, the driver should always check whether the tower crane foundation and base are abnormal. After closing the bottom main switch, check that the whole machine has no leakage phenomenon. After confirming that everything is correct, the driver can board the crane. During the boarding process, observe whether the tower body structure has deformation and whether the welds have cracks at any time.
Pre-operation checks are crucial for detecting any potential problems with the crane’s structure or electrical system. Any abnormalities in the foundation, base, or tower body could affect the crane’s stability and safety during operation.
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It is strictly prohibited for tower crane drivers and signalers to work under the influence of alcohol.
As mentioned earlier, alcohol impairs the judgment and reaction time of those responsible for operating and signaling the crane, which can have disastrous consequences in a construction site environment.
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Before starting the operation, an idle run should be carried out to check whether each working mechanism, brake, safety device, rope and pulley system, etc. are normal. Check the wear condition of the wire rope and whether it is threaded accurately through each pulley. The wire rope should be arranged neatly on the drum.
The idle run test helps to identify any mechanical or functional issues before the crane is put into actual operation. Checking the wire rope’s condition and its proper threading through the pulleys is essential for ensuring the safe lifting and lowering of loads.
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Tower crane drivers should cooperate well with signalers. They can only operate after receiving signals and should sound the bell to indicate.
Clear communication between the driver and the signaler is vital for the safe and accurate operation of the tower crane. The signaler provides instructions on the movement of the crane, and the driver must follow these signals precisely to avoid collisions and other accidents.
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Tower crane drivers should concentrate during operation. When operating the hoisting, slewing, and traction mechanisms, the handle shifting must be carried out in the order of stop, low, medium, high or high, medium, low, stop. Each gear should be held for at least 3 – 4 seconds before switching to the next gear. Quick gear skipping and sudden starting and stopping are not allowed.
This proper gear shifting technique ensures a smooth and controlled operation of the crane’s mechanisms. Sudden changes in speed or direction can cause the load to swing or the crane to become unstable, increasing the risk of accidents.
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The low-speed gear of the hoisting mechanism should not be used for more than 1.5 minutes within 10 minutes. It is strictly prohibited to use the low-speed gear for a long time, otherwise, there is a risk of burning out the motor of the hoisting mechanism.
The low-speed gear is designed for specific situations, such as starting with a heavy load or making precise adjustments. Prolonged use can cause the motor to overheat due to excessive current draw, leading to motor failure and potential load drops.
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When the tower crane is running, it is strictly prohibited for the hook to fall to the ground, otherwise, it will cause the wire rope to jump out of the pulley or drum, resulting in a wire rope breakage safety accident.
Allowing the hook to touch the ground can cause the wire rope to become misaligned or damaged, which can lead to a catastrophic failure of the lifting system.
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It is strictly prohibited to overload, exceed the torque, pull out piles, make oblique pulls or oblique lifts, directly hang loads with the hook, and use the tower crane to transport people.
These prohibited actions are extremely dangerous and can cause the crane to tip over, the load to fall, or other serious accidents. The crane is designed for specific lifting and moving operations within its rated capacity and parameters.
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When lifting heavy objects, sudden starting and sudden stopping are not allowed. During the process of the heavy object being lifted off the ground, the signaler should focus on checking whether the binding of the heavy object is reasonable. Only after confirming that everything is correct can the lifting continue.
Properly securing the load is essential for safe lifting. A poorly bound load can shift or fall during the lifting process, endangering workers and the surrounding area.
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During the operation of the tower crane, if any safety device alarms, the cause must be found out. It is not allowed to remove the safety device randomly and force the operation.
Safety devices are installed to protect the crane and its operators. If an alarm is triggered, it indicates a potential problem that must be investigated and resolved. Removing the safety device without addressing the issue can lead to a serious accident.
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If heavy rain, thick fog, or other severe weather conditions and a wind force exceeding level 6 occur during work, the operation should be stopped.
Adverse weather conditions can affect the crane’s stability, visibility, and the safety of its operation. Stopping work during such conditions helps to prevent accidents.
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When there are more than 2 tower cranes at a construction site, the horizontal distance between the tower cranes should ensure that there is at least 2 meters between the end of the lower boom and the other tower body; the vertical distance between the lowest part of the higher tower crane and the highest part of the lower tower crane should not be less than 2 metroak.
Proper spacing between multiple tower cranes is necessary to prevent collisions. These minimum distances are set to ensure the safe operation of each crane in a shared construction site environment.
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