In the vast world of architecture, steel structures, with their unique charm and excellent performance, have created countless stunning legendary works. Emerging during the Industrial Revolution and now excelling in the fields of super-high-rise and large-span buildings, steel structures, with their many advantages such as high strength, light weight, excellent seismic performance, and convenient construction, have become the mainstay of modern architecture, carrying humanity’s ultimate pursuit of architectural art and functionality. Below, let’s step into the wonderful world of the world’s top steel structure cases and explore the steel secrets and architectural wisdom behind them.
Eiffel Tower – The Steel Symbol of the Industrial Age
In 1889, a steel giant rose on the Champ de Mars in Paris, France. It is the Eiffel Tower. This building designed by Gustave Eiffel is not only a landmark of Paris but also an immortal monument in the development of steel structure buildings.
At that time, France was preparing for the World Expo to celebrate the 100th anniversary of the victory of the Great Revolution. Among many bidding schemes, Eiffel’s design stood out. It adopts four lattice girders to form a large tower frame, with the bottom spaced and the top converging. The unique shape not only meets the architectural aesthetics but also shows excellent structural stability. The entire tower is assembled from 18,038 metal parts. These parts are precisely manufactured in the factory with an accuracy of one-tenth of a millimeter and then transported to the site for assembly. During construction, wooden scaffolding and small steam cranes were built to assist the work. Workers spliced metal parts layer by layer. After 2 years, 2 months, and 5 days, the 324-meter-high (now 330 meters) tower was completed. It is worth mentioning that only one person was injured on duty during the construction, which fully demonstrates the advanced construction management level at that time.
The completion of the Eiffel Tower marked the successful application of steel materials in large-scale building structures and opened a new era of architecture. Since then, steel structure buildings have emerged around the world like mushrooms after rain, adding a unique steel style to the urban skyline.
“Bird’s Nest” Stadium – A Model of Steel Structures in Sports Architecture
The “Bird’s Nest” stadium, the main stadium of the 2008 Beijing Olympics, has become a classic work of world sports architecture and an outstanding example of steel structure application with its unique shape and large scale.
In terms of design concept, the “Bird’s Nest” resembles a bird’s nest in nature. The external nest-like structure is all made of steel, with a total steel weight of 42,000 tons. As China’s first non-linear building, its construction faces many challenges: there are no existing standards to follow and no experience to learn from. Li Jiulin, the chief engineer of the project, led the team to first overcome the problem of steel selection for key parts of the external steel structure. After repeated screening, the steel numbered Q460E became the ideal choice. This kind of steel will be completely deformed only when the stress intensity exceeds 460 MPa. Its strength is nearly twice that of ordinary steel, and it has excellent toughness. However, at that time, there was no application precedent in China’s construction industry, and relying on imports was costly. Li Jiulin’s team, together with cooperative units, successfully achieved mass production of domestic Q460E steel after thousands of experiments, laying a solid foundation for the project.
In order to efficiently manage tens of thousands of steel structure drawings and a large number of steel components with different shapes, the team, together with Tsinghua University, pioneered the “movement” of steel structures into computers and used BIM (Building Information Modeling) technology to provide engineers with a “God’s perspective”, clearly presenting complex structures and helping the construction proceed smoothly. In the welding process, due to the poor weldability of the new steel, the team spent 5 months and repeated tests with more than 100 kinds of steel to formulate a complete set of welding parameters and standards to ensure the quality of the welds with a total length of more than 300,000 meters, and the welding yield reached 100%. Finally, after more than 1,800 days and nights of hard work, the “Bird’s Nest” was successfully completed, showing the world China’s superb skills and innovative strength in the field of steel structure construction.
Burj Khalifa – The Pinnacle of Super High-Rise Steel Structures
The Burj Khalifa in Dubai, with an amazing height of 828 meters, stands at the top of the world’s buildings and is the epitome of super high-rise steel structure buildings.
The Burj Khalifa adopts a unique Y-shaped plane design, which not only has aesthetic value but also can effectively reduce the force of wind on the tower and enhance structural stability. Its structural system can be described as a buttress core tube. Three wing-shaped structures are anchored to the hexagonal central core tube. Each wing supports each other to form a stable system. The central core tube provides torsional resistance, and the wing-shaped structures resist wind shear. In terms of foundation construction, a large reinforced concrete raft foundation is adopted, which is 3.7 meters thick. A total of 12,500 cubic meters of concrete is poured in four times. The raft is supported by reinforced concrete piles with a diameter of 1.5 meters and a length of 43 meters to ensure that the building is firmly rooted in the ground.
During the construction process, the Burj Khalifa used a lot of advanced technologies and materials. Its external curtain wall is composed of double-layer glass inlaid in an aluminum frame. Nearly 26,000 glass panels are all hand-cut, each weighing 362 kilograms, and with an energy-saving silver coating to cope with the hot climate in Dubai. The retractable spire weighing more than 4,000 tons is lifted into place from the inside of the building by a hydraulic pump. It is not only a landmark element of the building but also plays an important role in structural design, with communication equipment inside. The completion of the Burj Khalifa has set many new records for super high-rise buildings and demonstrated the strong power of steel structures in realizing human dreams of high altitudes.
Chongqing China Mall – Innovative Practice of Large-Span Steel Structures
Chongqing China Mall project, as Asia’s first world-class tourism and shopping complex, has written a new chapter in the field of steel structures. It adopts a large-span double-layer free-form orthogonal and square grid structure. The supporting system is composed of 44 steel columns and central steel diagonal braces around it. Compared with the National Centre for the Performing Arts, it has made breakthroughs in the total weight of steel structures, structural span, structural height, construction difficulty, etc., creating new records.
The upper steel roof of the central core area of the project has a complex shape, with a north-south span of 150 meters, an east-west span of 250 meters, a roof center elevation of 65 meters, and a rise of about 35 meters. In order to release the radial horizontal thrust of the roof truss, a one-way sliding steel support is used to connect the column top with the roof. The support is designed according to European standards, with large circumferential horizontal reaction force. It takes the lead in China to adopt high-strength and low-friction sliding material – high-performance modified ultra-high molecular weight polyethylene, with a compressive strength of 180MPa and a lateral shear force of more than 15,000kN, which is far better than conventional PTFE materials. In the roof unloading stage, the structure is transformed from multi-point support to surrounding support. In order to reduce the assembly height of the steel structure, the middle lifting area is lifted three times cumulatively, with a maximum lifting height of 46 meters and a maximum lifting weight of about 3,000 tons. In addition, the skylights of the commercial buildings at the four corners of the central amusement area adopt a string beam structure, and the prestressed struts adopt non-swinging triangular fixed struts, which innovatively solve the problem of cable installation. The successful construction of Chongqing China Mall shows the innovative application and excellent practice of large-span steel structures under the demand of complex building functions.
Beijing Daxing International Airport – A Masterpiece of Complex Spatial Steel Structures
The terminal building of Beijing Daxing International Airport, with its large scale and unique shape, has become one of the world’s largest and most difficult complex spatial steel structure projects. Eight uniquely shaped C-shaped columns support a complex curved spatial grid steel roof with an area of 180,000 square meters, with a maximum span of 180 meters and a fluctuation difference of nearly 30 meters. There are more than 70,000 structural members, all of which are different, and there are concrete structural floors of different heights below, making the construction difficulty unimaginable.
Jinggong Steel Structure, the contractor, applied a number of innovative technologies in the project. The construction idea of “zoned installation, zoned unloading, deformation coordination, and overall closure” is adopted. The super large roof is divided into 6 major zones and 39 construction blocks. A variety of processes such as floor in-situ installation, block lifting, cumulative lifting, and large crawler crane off-site hoisting are combined. Through construction simulation and precision control, the high-precision docking of the 2,000-meter-long closure line and the precise control of the structural configuration are realized, and the roof structure is capped in only 80 days. In the block cumulative lifting construction, 25 automatically controlled hydraulic lifters are used to complete the installation of the largest block roof with an area of 20,000 square meters, a weight of 2,196 tons, and a height difference of 21.5 meters, breaking through the constraints of construction conditions. Aiming at the problem of high processing precision requirements of C-shaped columns, laser scanning inverse imaging digital pre-assembly technology is applied, saving 70% of assembly time and 80% of cost. At the same time, high-strength steel robot automatic welding technology and welding stress and deformation control technology are used to ensure welding quality, and the “Jingzhu BIM + project digital collaboration platform” is applied to realize the whole life cycle dynamic management of the project. The completion of Beijing Daxing International Airport demonstrates the innovative height and technical strength of complex spatial steel structure buildings.
These world’s top steel structure cases are like shining beacons, illuminating the path of architectural development. They are not only treasures of architectural art but also crystallization of scientific and technological innovation, witnessing the brilliant course of steel structures constantly breaking through limits and creating miracles in the field of architecture. With the continuous progress of science and technology, steel structure buildings will surely build a better living space for mankind with a more excellent attitude and continue to write immortal legends in the history of architecture.
