2025-01-13    80

　　In the context of steel structure companies, high-rise steel structures typically refer to buildings with six stories or more (or exceeding 30 meters in height). These structures primarily utilize steel sections and plates connected or welded into components, which are then further assembled and welded into a structural system. High-rise steel structures commonly adopt steel frame structures or steel frame-concrete core tube structural forms. The latter is more widely used in modern high-rise and super high-rise steel structures, essentially belonging to steel-concrete hybrid structures.

　　1.Rigid Belt Truss Frame Structure

　　To connect the outer columns of the frame structure with the internal belt truss, rigid belt trusses can be installed at the middle and top of the building. The Wisconsin Bank Building constructed in Milwaukee in 1974 serves as a prime example.

　　2.Frame Tube Structure

　　When all components are interconnected in some way, the entire building resembles a hollow tube or a rigid box emanating from the ground. At this point, the entire structure of the high-rise building achieves maximum efficiency in resisting wind loads in terms of strength and stiffness.

　　This special structural system was first employed in the 43-story reinforced concrete Dwight Eisenhower Apartment Building in Chicago. However, the most striking application of this structural system is the 100-story twin-tube World Trade Center in New York.

　　3.Braced Truss Tube

　　The outer columns of the building can be arranged at independent intervals or interconnected through diagonal braces crossing the centerlines of beams and columns, forming a tube structure that works together. This type of high-rise structural system was first adopted in Chicago's John Hancock Center. The steel consumption of this project is comparable to that of traditional 40-story buildings.

　　4.Tube Structures

　　As the demand for even taller buildings continues to increase, tube structures and braced truss tubes are designed in bundled form to create larger tubes, maintaining the building's high performance. Chicago's 110-story Sears Roebuck Headquarters Building has nine tubes divided into three parts from the foundation. The terminals of these independent tubes are located at different heights within the building, fully demonstrating the potential for architectural style freedom inherent in this new structural concept. At 1,450 feet (442 meters) tall, this building was once the tallest in the world.

　　5.Thin-Walled Tube Systems

　　This tube structural system is designed to enhance the lateral force resistance (wind and seismic loads) and lateral displacement resistance of supertall buildings. The thin-walled tube represents another significant leap forward in tube systems.

　　The advancement of thin-walled tubes utilizes the building's facade (walls and slabs) as structural components working in conjunction with the tube, providing an effective means for high-rise buildings to resist lateral loads. It also allows for column-free interior spaces with lower costs and a higher ratio of usable area to gross floor area. Due to the contribution of the thin-walled facade, the components of the entire frame tube do not require excessive mass.

　　This makes the structure both lightweight and economical. All typical columns and window sill beams are rolled sections, minimizing the use and consumption of composite members. The thickness around the beams can also be appropriately reduced. The size of wall beams, which can occupy valuable space, can also be controlled to the greatest extent.

　　This structural system has been employed in the One Mellon Bank Center in Pittsburgh. Systems in Reinforced Concrete: Although high-rise steel structures have an earlier start, the development of high-rise reinforced concrete buildings has been rapid, becoming a strong competitor to steel structural systems in both office buildings and apartment residences.

　　6.Frame Tube

　　As mentioned earlier, the concept of the frame tube was first adopted in the 43-story Dwight Eisenhower Apartment Building. In this building, the column spacing for the outer columns is 5.5 feet (1.68 meters). The inner columns support 8-inch-thick slab-less floors. Tube-in-Tube Structure: Another reinforced concrete system for office buildings combines traditional shear wall structures with outer frame tubes.

　　This system consists of an outer frame with small column spacing and a rigid shear wall tube surrounding the central equipment area. This tube-in-tube structure allows the overall cost of the tallest lightweight concrete building in the world (the Shell Plaza Building in Houston) to be comparable to that of a traditional 35-story shear wall structure. Hybrid systems combining steel and concrete structures have also evolved. A good example is the hybrid system designed by Skidmore, Owings & Merrill.

　　In this system, the external concrete frame tube surrounds the internal steel frame, combining the advantages of both reinforced concrete and steel structural systems. The 52-story Shell Plaza Building in New Orleans utilizes this system. Steel structure refers to a structure in which steel plays a dominant role in the building's structure, encompassing a broad concept. Most steel structures involve architectural design, engineering technology, and craftsmanship.