Jib Tower Cranes: Advantages in Performance and Safety Threats

At present, many countries clearly specify in their building regulations that hoisting operations must remain within the boundaries of the construction site, meaning that the jib extends cannot surpass the construction fences. While the traditional horizontal arm tower crane may be more cost-effective than jib cranes of similar tonnage and lifting torque—and can lift heavy objects at a faster luffing speed—it struggles to meet the demands of today's super high-rise buildings.

To elaborate, construction sites tend to be relatively small, particularly in urban centers, which limits the effectiveness of horizontal arm tower cranes. Additionally, modern super high-rise structures typically incorporate concrete-filled steel tubes, steel beams, and various embedded components. These steel structures and the heavy embedded parts at the joints can weigh more than 40 tons, making it challenging for horizontal arm tower cranes to provide sufficient lifting capacity and torque.

To enhance efficiency and reduce project timelines, it's common for multiple tower cranes to operate concurrently. In this context, jib cranes offer significant advantages over horizontal arm tower cranes, particularly in lifting capacity and torque. Additionally, jib tower cranes are known for their strong safety features and stability, especially when not in operation and during windy conditions. With the evolving trends in the construction industry, we've witnessed a reduction in the size of construction sites. The increasing use of jib tower cranes in the construction of skyscrapers, particularly in densely populated cities, aligns well with contemporary requirements, signaling a probable rise in their usage. These cranes play a vital role in the on-site operations of tall building projects.

Throughout various construction phases, different tasks rely heavily on the support of tower cranes. In regions prone to high-intensity seismic activity, these cranes face unique challenges during construction. As a result, ensuring their safety has become paramount when it comes to the construction of super high-rise buildings.

Tower cranes function as multi-degree-of-freedom systems, typically positioned atop building structures. They carry substantial loads—self-weight, hoisting loads, and other operational loads—that are transferred through embedded components connected to the wall joints of towers. Ultimately, these forces are directed to the primary structure of the skyscrapers, making the integrity of the connections at the wall joints essential for overall safety. It is therefore crucial to understand how the force actions at these joints impact safety performance, based on their working mechanisms.

In view of this, the force performance of attached to the wall joints of high-performance jib tower cranes, was investigated through scale model test and numerical simulation in this study. A pullout test was executed, varying the parameters of the embedded sections in the scale model, while the entire testing process was simulated using finite element methods for a thorough comparative analysis of the results. The main objective was to identify the factors affecting anchor capacity, explore the damage mechanisms, and assess the impact of various parameters on the wall joints of tower cranes. Additionally, we aimed to evaluate the force performance and working mechanisms of these joints to enhance their seismic resilience.