Jin Mao Tower - Shanghai, China

The composite structural system for the Jin Mao Tower was designed to resist typhoon winds and earthquake forces and accommodate poor soil conditions while providing a very slender tower to be fully occupied for office and hotel uses. Reinforced concrete, structural steel and the combined use of structural steel and reinforced concrete (composite) members are used for the structural system. Reinforced concrete, with its excellent mass, strength, stiffness, and damping characteristics, combined with the strength, speed of construction, long-span capabilities, and lightweight characteristics of structural steel are used in the Jin Mao Tower. The structural system for the Tower responds to the Client's request to utilize local materials and labor expertise related to reinforced concrete, traditionary preferred for buildings in Shanghai. Reinforced concrete is strategically placed to utilize its excellent compression characteristics while structural steel is used for extreme tension conditions. Loads in the Tower are optimally controlled to distribute forces correctly and efficiently. The structural solution to the Jin Mao Tower illustrates that even with moderately high strength concrete compressive strengths, reinforced concrete is an effective solution to ultra-tall structures. The advantages of concrete pumping technologies related to pumping volumes and pumping heights and advanced self-climbing forming systems have made concrete a strong competitor to structural steel when considering the construction of such towers. Reinforced concrete provides excellent structural behavior characteristics when subjected to extreme wind loadings. The inherent, passive structural characteristics of reinforced concrete provides excellent dynamic properties, reducing building accelerations, and therefore minimizing occupant perception. This paper addresses an international design approach for a very tall building located in the Far East, specifically in Shanghai, The People's Republic of China, and focuses on the mixed use of concrete and structural steel with its effect on structural efficiency within the superstructure structural system, concrete material availability, wind and seismic engineering based on local and international standards, and foundation engineering specific to poor local soils. In addition, differential movement due to creep, shrinkage, and elastic shortening will be discussed primarily relating to the mixed use of concrete and structural steel within this truly composite structural system.